U.S. Geological Survey

U.S. Department of the Interior

Geochemical Data for Mercury, Methylmercury, 

and Other Constituents in Sediments from

Englebright Lake, California, 2002

Data Series 151

CALFED Ecosystem Restoration Program, California Bay–Delta Authority, and

California Resources Agency
Photograph on front cover: Three cores from Englebright Lake, site 8, showing correlation of 

stratigraphy, November 11, 2002. Photograph by Noah P. Snyder.
Geochemical Data for Mercury, 

Methylmercury, and Other Constituents 

in Sediments from Englebright Lake, 

California, 2002

By Charles N. Alpers1, Michael P. Hunerlach1, Mark C. Marvin-DiPasquale2, 

Ronald C. Antweiler3, Brenda K. Lasorsa4, John F. De Wild5, and Noah P. Snyder6

Prepared in cooperation with the 

CALFED Ecosystem Restoration Program, the California Bay–Delta Authority, and the 

California Resources Agency

Data Series 151

U.S. Department of the Interior

U.S. Geological Survey

1

U.S. Geological Survey, 6000 J Street, Placer Hall, Sacramento, CA 95819-6129.

2

U.S. Geological Survey, 345 Middlefield Road, Mailstop 480, Menlo Park, CA 94025.

3

U.S. Geological Survey, 3215 Marine Street, Suite E-127, Boulder, CO 80303.

4

Battelle Marine Sciences Laboratory, 1529 West Sequim Bay Road, Sequim, WA 98382.

5

U.S. Geological Survey, 8505 Research Way, Middleton, WI 53562.

6

Dept. of Geology and Geophysics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467.
U.S. Department of the Interior

Dirk Kempthorne, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2006

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reproduce any copyrighted materials contained within this report.

Suggested reference:

Alpers, C.N., Hunerlach, M.P., Marvin-DiPasquale, M.C., Antweiler, R.C., Lasorsa, B.K., De Wild, J.F., and Snyder, N.P., 

2006, Geochemical data for mercury, methylmercury, and other constituents in sediments from Englebright Lake, 

California, 2002: U.S. Geological Survey Data Series 151, 95 p.
v

Contents

Abstract ................................................................................................... 1

Introduction................................................................................................ 2

Previous Work and Related Investigations ............................................................ 2

Purpose and Scope .............................................................................. 4

Acknowledgments................................................................................. 5

Reservoir Sampling ....................................................................................... 5

Deep Coring Campaign ........................................................................... 5

Shallow Coring Campaign ........................................................................ 7

Laboratory Methods.. ........................................................................................10

Total Mercury.......................................................................................10

Methylmercury ....................................................................................10

Trace and Major Elements........................................................................11

Mercury Methylation Potential ..................................................................11

Heavy Minerals ....................................................................................12

Quality Assurance and Quality Control ............................................................... 12

Total Mercury.......................................................................................12

Methylmercury ....................................................................................13

Trace and Major Elements........................................................................21

Results...................................................................................................... 22

Total Mercury and Methylmercury ............................................................22

Trace and Major Elements .....................................................................43

Mercury Methylation Potential ..................................................................44

Heavy Minerals ....................................................................................48

Summary and Conclusions .............................................................................. 51

References Cited.......................................................................................... 52

Appendixes ................................................................................................ 56

Appendix A. Quality Assurance and Quality Control Data for Mercury and 

Methylmercury Analyses........................................................................ 57

Appendix B. Quality Assurance, Quality Control, and Data Tables for Trace and 

Major Elements ................................................................................. 67

Appendix C. Mineralogical and Grain-Size Distribution Data for 

Heavy Mineral Concentrates .................................................................. 82

Appendix D. Scanning Electron Microscope Photomicrographs Showing Gold and 

Amalgam Textures from the Heavy Mineral Concentrates from 

Englebright Lake, California, 2002 ............................................................ 86
vi

Figures

Figure 1. Map showing location of Englebright Lake in the Yuba River watershed, 

California ....................................................................................... 3

Figure 2. Map showing locations of deep and shallow coring, Englebright Lake, 

California ....................................................................................... 8

Figure 3. Detailed maps of sampling locations at Englebright Lake, California .................. 9

Figure 4. Deep coring profiles showing concentrations of trace metals and 

median grain size in sieved sediment subsamples (Y-series) from site 1 at 

Englebright Lake, California, May–June, 2002 ............................................. 31

Figure 5. Deep coring profiles showing concentrations of trace metals and 

median grain size in unsieved sediment subsamples (Y-series) from site 4 at 

Englebright Lake, California, May–June, 2002 ............................................. 32

Figure 6. Deep coring profiles showing concentrations of trace metals and 

median grain size in sieved sediment subsamples (Y-series) from site 7 at 

Englebright Lake, California, May–June, 2002 ............................................. 33

Figure 7. Deep coring profiles showing concentrations of trace metals and 

median grain size in sieved sediment subsamples (Y-series) from site 9 at 

Englebright Lake, California, May–June, 2002 ............................................. 34

Figure 8. Deep coring profiles showing concentrations of trace metals and 

median grain size in sieved sediment subsamples (Y-series) from site 8 at 

Englebright Lake, California, May–June, 2002 ............................................. 35

Figure 9. Plots showing relations with depth for unsieved sediment subsamples (shallow 

cores and selected deep cores) at Englebright Lake, California, May–June, 2002: 

(A) Total mercury, (B) Methylmercury, (C) Ratio of methylmercury to total mercury, 

and (D) Median grain size ..................................................................... 36

Figure 10.Plots showing 203Hg(II)-methylation potential rate as a function of depth for 

sediments from Englebright Lake, California, 2002: (A) Sites 1 and 11, 

(B) Sites 4 and 10, (C) Sites 9 and 12......................................................... 46

Figure 11.Plots showing correlation of the 203Hg(II)-methylation potential rate for shallow 

sediments from Englebright Lake, California, 2002: (A) Redox potential, (B) pH ...... 48

Figure 12.Plots showing correlation of the ratio of methylmercury to total mercury 

with forms of iron and carbon in shallow sediments from Englebright Lake, 

California, 2002................................................................................. 49

Figure 13.Photograph showing gold and amalgam grains from heavy-mineral concentrate 

5A from Englebright Lake, California ...................................................... 50

Figure 14.Longitudinal section showing gold tenor in composite core intervals from 

Englebright Lake, California, 2002............................................................ 51

Appendix A. Quality Assurance and Quality Control Data for Mercury and 

Methylmercury Analyses:

Figure A1. Graph showing results of analysis by two laboratories of total mercury in 

split subsamples from Englebright Lake, California, 2002................................. 57

Figure A2. Graph showing results of analysis by two laboratories of methylmercury in 

split subsamples from Englebright Lake, California, 2002.................................... 57
vii

Appendix D. Scanning Electron Microscope Photomicrographs Showing Gold and 

Amalgam Textures from the Heavy Mineral Concentrates from 

Englebright Lake, California, 2002 :

Figure D1. Amalgam grain showing abrasion from processing (sample 5A) .................. 86

Figure D2. Two scanned electron microscope images of pseudo-hexagonal hematite 

platelets surrounded by mercury-rich halo, (A) Backscatter, 

(B) Secondary electron ..................................................................... 87

Figure D3. Gold grain with iron oxide (sample 5A7) ................................................ 88

Figure D4. Gold grain with abundant diagenetic pyrite crystals (sample 5AC1) ............... 88

Figure D5. Iron-oxide coated gold nugget and clean gold nugget (sample 5AC2) ............ 89

Figure D6. High magnification of pitted surface of gold nugget (sample 7B1) .................. 89

Figure D7. Extensive cracking of amalgam in mercury-saturated gold nugget 

(sample 7B1).................................................................................... 90

Figure D8. Close-up view of nugget showing abrasion of amalgam in cavity with 

euhedral quartz crystal (sample 9B) ...................................................... 90

Figure D9 . Amalgam grains (sample 9B) (A) Aggregate containing amalgam crystal 

in upper right, and (B) Close-up view of the amalgam crystal ........................... 91

Figure D10. Placer gold grain of high purity, no visible mercury (sample 9B8) 

(A) View of entire grain, (B) Close-up view showing smooth texture of gold ......... 92

Figure D11. Large, pitted gold grain with 100-micrometer, euhedral zircon 

crystal (sample 3B1)........................................................................... 93

Figure D12. Grain of gold containing small beads of elemental mercury (sample 3B3)......... 93

Figure D13. Grain of amalgam showing smearing from processing (sample 3B4)............... 94

Figure D14. Grain of amalgam showing fracture (sample 3B5) .................................... 94

Figure D15. Octahedral crystal forms of gold in vug of nugget (sample 8A1) .................. 95

Figure D16. Iron-stained gold nugget with no trace of mercury (sample 2B1) .................. 95

Tables

Table 1. Basic data for sediment sample series from Englebright Lake, California, 2002 ...... 6

Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, 

California, May–June 2002 .................................................................. 14

Table 3. Mercury and methylmercury data from the MEM series of subsamples from 

deep cores, Englebright Lake, California, May–June 2002 .............................. 23

Table 4. Mercury and methylmercury data for shallow cores taken at Englebright Lake, 

California, October 2002 ..................................................................... 28

Table 5. Statistical data showing longitudinal variation in mercury and methylmercury 

concentrations in sediments collected during 2002 from Englebright Lake, 

California ....................................................................................... 37

Table 6. Statistical data showing vertical variation in the mercury and methylmercury 

concentrations of sediments collected during 2002 from Englebright Lake, 

California ....................................................................................... 39

Table 7. Statistical data showing longitudinal variation in concentrations of select trace 

metals in sediments collected during 2002 from Englebright Lake, California ......... 41

Table 8. Whole-sediment 203Hg(II)-methylation rate constants and calculated potential 

rates for shallow and deep sediments (MP series) from Englebright Lake, 

California, 2002................................................................................. 45
viii

Table 9. Chemical data for the MP series of sediment samples from Englebright Lake, 

California, 2002................................................................................. 47

Table 10. Chemical data for pore water from the MP series of sediment samples from 

Englebright Lake, California, 2002............................................................ 50

Table A1. Total mercury concentrations in standard reference materials. ........................ 58

Table A2. Total mercury data for replicate sediment subsamples from Englebright Lake, 

California, 2002................................................................................. 60

Table A3. Methylmercury concentrations in standard reference materials. ..................... 62

Table A4. Methylmercury data for replicate sediment subsamples from Englebright Lake, 

California, 2002 .............................................................................. 65

Table A5. Comparison of results from two laboratories for total mercury and methylmercury in split sediment subsamples from Englebright Lake, California, 2002 ...... 66

Table B1. Concentrations of trace metals and major elements in standard 

reference materials ........................................................................... 67

Table B2. Data for trace metals and major elements in digestion blanks ........................ 76

Table B3. Recovery data for trace-metal spikes in sediment samples from Englebright Lake, 

California, 2002 .............................................................................. 81

Table B4. Data for trace metals and major elements in replicate sediment subsamples from 

Englebright Lake, California, 2002............................................................ 81

Table B5. Data for trace metals and major elements from the Y series of subsamples from 

the May–June 2002 deep cores from Englebright Lake, California ..................... 81

Table C1. Particle-size distribution of bulk composite core samples prior to preparation of 

heavy mineral concentrates, Englebright Lake, California, 2002 ........................ 82

Table C2. Particle-size distribution and gold tenor of heavy mineral concentrates, 

Englebright Lake, California, 2002............................................................ 83

Table C3. Mineralogical data from magnetic separation and optical microscopy for 

heavy mineral concentrates, Englebright Lake, California, 2002 ........................ 84

Table C4. Summary of textural observations by scanning electron microscope on gold and 

amalgam in heavy mineral concentrates, Englebright Lake, California, 2002 ......... 85
ix

Conversion Factors, Datums Used, and Abbreviations

Conversion Factors—SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

kilometer (km) 0.6214 mile (mi)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

meter (m) 1.094 yard (yd) 

nanometer (nm) 3.0937 x 10–8 inch (in.)

Area

square kilometer (km2) 247.1 acre

square centimeter (cm2) 0.001076 square foot (ft2)

square meter (m2) 10.76 square foot (ft2) 

hectare (ha) 0.003861 square mile (mi2) 

square kilometer (km2) 0.3861 square mile (mi2)

Volume

cubic meter (m3) 264.2 gallon (gal) 

cubic centimeter (cm3) 0.06102 cubic inch (in3) 

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 1.308 cubic yard (yd3) 

cubic meter (m3) 0.0008107 acre-foot (acre-ft) 

liter (L) 61.02 cubic inch (in3) 

liter (L) 0.2642 gallon (gal)

milliliter (mL) 0.0610 cubic inch (in3)

Mass and Mass Flux

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound, avoirdupois (lb)

megagram (Mg) 1.102 ton, short (2,000 lb)

megagram (Mg) 0.9842 ton, long (2,240 lb)

metric ton per day (tonne/d) 1.102 ton, short, per day (ton/d) 

megagram per day (Mg/d) 1.102 ton, short, per day (ton/d) 

megagram per day per square 

kilometer [(Mg/d)/km2]

2.8547 ton, short, per day per square mile 

[(ton/d)/mi2]

megagram per year (Mg/yr) 1.102 ton, short, per year (ton/yr)

metric ton per year (tonne/yr) 1.102 ton, short, per year (ton/yr) 

Radioactivity

becquerel per liter (Bq/L) 27.027 picocurie per liter (pCi/L) 

Datums Used

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.
x

Acronyms, Abbreviations, and Chemical Notation

Acronyms

ASL, above sea level

ASTM, American Society for Testing and Materials

BMSL, Battelle Marine Sciences Laboratory (Sequim, Washington)

CRV, certified reference value

CVAAS, cold vapor atomic-absorption spectrometry

CVAFS, cold vapor atomic-fluorescence spectrometry

DI, deionized (water)

DOC, dissolved organic carbon

EDS, energy dispersive spectrometer

IAEA, International Atomic Energy Agency

ICP–AES, inductively coupled plasma–atomic emission spectrometry 

ICP–MS, inductively coupled plasma–mass spectrometry

MD, methylmercury degradation

MDL, method detection limit

MEM series, MEthylMercury sample series

MP, methylmercury production (sample series)

NIST, National Institute of Standards and Technology

QA, quality assurance

QC, quality control

RPD, relative percentage difference

RSD, relative standard deviation

SEM, scanning electron microscope

SR, sulfate reduction

SRM, standard reference material

USEPA, United States Environmental Protection Agency

USGS, United States Geological Survey

UYRSP, Upper Yuba River Studies Program

WDML, Wisconsin District Mercury Laboratory (Middleton, Wisconsin)

Abbreviations 

cm, centimeter

cm3, cubic centimeter

g, gram

kg, kilogram

L, liter

mCi/mg, millicurie per milligram

mg, milligram

mg Au/m3, milligram of gold per cubic meter 

MΩ-cm, megaohm-centimeter

μCi/100 μL, microcurie per 100 microliters

μg, microgram

μm, micrometer

ng, nanogram

ng/g, nanogram per gram

ng Hg/g dry sediment/d, nanograms of mercury per gram dry sediment per day

ppb, parts per billion
xi

ppm, parts per million R2

, coefficient of determination for linear least-squares regression

rpm, revolutions per minute

t/km

2

/yr, tonnes per square kilometer per year

wt, weight

>, greater than

<, less than

~, approximately, about

Chemical Elements

Al, aluminum

As, arsenic

Au, gold

B, boron

Ba, barium

Be, beryllium

Bi, bismuth

Ca, calcium

Cd, cadmium

Ce, cerium

Cl, chloride

Co, cobalt 

Cr, chromium

Cs, cesium

Cu, copper

Dy, dysprosium

Er, erbium 

Eu, europium 

Fe, iron

Gd, gadolinium

Ho, holmium 

Hg, mercury

In, indium 

Ir, iridium

K, potassium

La, lanthanum

Li, lithium

Lu, lutetium 

Mg, magnesium

Mn, manganese

Mo, molybdenum

N, nitrogen

Na, sodium

Nd, neodymium

Ni, nickel

P, phosphorus

Pb, lead

Pr, praseodymium

Rb, rubidium

Re, rhenium
xii

Rh, rhodium

S, sulfur

Sb, antimony

Se, selenium

Si, silicon

Sm, samarium

Sn, tin

Sr, strontium

Tb, terbium

Te, tellurium

Th, thorium

Ti, titanium

Tl, thallium

Tm, thulium 

U, uranium

V, vanadium

W, tungsten

Y, yttrium

Yb, ytterbium 

Zn, zinc

Zr, zirconium

Chemical Compounds, Isotopes, and Other Chemical Notation

CH3

203Hg+

, methylmercury ion with radiolabeled mercury

CH4, methane

CH2Cl2, methylene chloride

CuSO4, copper sulfate

Fe(II), ferrous (divalent) iron

Fe(III), ferric (trivalent) iron

HCl, hydrochloric acid

HF, hydrofluoric acid

HNO3, nitric acid

Hg0, elemental mercury

Hg+, mercurous ion

Hg2+, mercuric ion

Hg(II), divalent mercury

HgCl2, mercuric chloride 

HgT, total mercury

203Hg(II), mercury-203 radiotracer divalent inorganic mercury

KBr, potassium bromide

MeHg, methylmercury (monomethylmercury)

N2, nitrogen gas

NaBEt4, sodium tetra-ethyl borate 

O2, oxygen gas

SiO2, silicon dioxide, or silica

SnCl2, stannous chloride
Abstract 

This report presents geochemical data from two 2002 

sampling campaigns conducted in Englebright Lake on the 

Yuba River in northern California. A deep coring campaign 

was done in May–June 2002 and a shallow sampling campaign 

was completed in October 2002. This work assessed the chemical composition of material deposited in the reservoir between 

1940, the year Englebright Dam was completed, and 2002 

as part of the Upper Yuba River Studies Program, an effort 

designed to evaluate the feasibility of introducing anadromous 

fish, including steelhead and spring-run Chinook salmon, 

upstream from Englebright Dam. Results of analyses of total 

mercury (HgT) in 444 subsamples, methylmercury (MeHg) in 

243 subsamples, and other trace and major elements in 202 

subsamples are presented. Data quality was evaluated on the 

basis of analyses of replicate pairs of subsamples, standard 

reference materials, blanks, and spike additions. 

Deep coring penetrated the full thickness of material 

deposited after 1940 at six locations in the reservoir; the cores 

reached a maximum depth of 32.8 meters below the reservoir 

floor. At the three deep coring sites closest to Englebright 

Dam, concentrations of HgT (dry basis) were consistently in 

the range of 100 to 500 ng/g (nanogram per gram), in sediment dominantly of silt size (median grain size of 0.004 to 

0.063 mm [millimeter]). At the deep coring sites located 

farther upstream, the upper parts of the profile had lower 

concentrations of HgT, generally ranging from 2 to 100 ng/g, 

in sediment dominantly of sand size (median grain size from 

0.063 to 2 mm). The lower part of the vertical profiles at three 

upstream coring sites had higher concentrations of HgT than 

the upper and middle parts of these profiles, and had finer 

median grain size. 

The highest median concentration of MeHg (1.1 ng/g) 

was in the top 2 cm (centimeter) of the shallow box cores. 

This vertical interval also had the highest value of the ratio of 

MeHg to HgT, 0.41 percent. Median concentrations of MeHg 

and median values of MeHg/HgT decreased systematically 

with depth from 0–4 to 4–8 to 8–12 cm in the shallow cores. 

However, similar systematic decreases were not observed at 

the meter scale in the deep cores of the MEM (MEthylMercury) series. The overall median of the ratio MeHg/HgT in the 

deep cores was 0.25 percent, not much less than the overall 

median value for the shallow cores (0.33 percent). 

Mercury-203 radiotracer divalent inorganic mercury 

(203Hg(II)) was used to determine microbial mercury-methylation potential rates for 11 samples collected from three 

reservoir locations and various depths in the sediment profile. 

For the five shallow mercury-methylation subsamples, ancillary geochemical parameters were assayed, including microbial sulfate reduction rates, sulfur speciation (sediment acid 

volatile sulfide, total reduced sulfur, and pore-water sulfate), 

iron speciation (sediment acid extractable iron(II), amorphous 

iron(III), crystalline iron(III) and pore-water iron(II)), porewater chloride and dissolved organic carbon, and pH, oxidation-reduction potential (Eh) and whole-sediment organic 

content. The highest potential rates of microbial mercury 

methylation were measured in shallow (0 to 8 cm depth) sediments (5 to 30 nanograms of mercury per gram dry sediment 

per day), whereas potential rates for subsamples collected 

from depths greater than 500 cm were consistently below the 

detection limit of the radiotracer method (< 0.02 nanogram of 

mercury per gram dry sediment per day). 

Chemical analyses of trace and major elements in bed 

sediment are presented for 202 samples from deep cores from 

five locations in Englebright Lake. The mean values and standard deviations for selected trace elements were as follows 

(in micrograms per gram): antimony, 2.4 ± 1.6; arsenic, 

69 ± 48; chromium, 134 ± 23; lead, 33 ± 25; and nickel, 

87 ± 24.

Concentrated samples of heavy-mineral grains, prepared 

using nine large-volume composite samples from deep cores, 

were examined using optical and scanning-electron microscopy. Estimated gold concentrations in the composite sediment samples ranged from 38 to 840 milligrams per cubic 

meter. Grains of gold-mercury amalgam and grains of electrum (native gold), with and without mercury staining, were 

observed in the heavy-mineral concentrates.

Geochemical Data for Mercury, Methylmercury, and 

Other Constituents in Sediments from Englebright Lake, 

California, 2002

By Charles N. Alpers, Michael P. Hunerlach, Mark C. Marvin-DiPasquale, Ronald C. Antweiler, 

Brenda K. Lasorsa, John F. De Wild, and Noah P. Snyder
Results of this study will be used to evaluate potential 

effects on fish habitat and trace-element transport in relation 

to various scenarios regarding efforts to improve fish passage 

at Englebright Lake. The scenarios include dredging or release 

of sediments to downstream environments in association with 

dam modification or removal. 

Introduction

Harry L. Englebright Lake (Englebright Lake; fig. 1) is a 

14-kilometer-long reservoir located on the Yuba River in the 

Sierra Nevada foothills of northern California. The reservoir 

is impounded by Englebright Dam, which is 80 m (meter) tall 

and was completed in December 1940 by the California Debris 

Commission. Its primary purpose was to help mitigate flood 

risk in the Central Valley around Marysville by impounding 

sediment from anticipated future hydraulic-mining activity in 

the watershed upstream. At present, the reservoir is a popular 

destination for recreational boaters and campers and is a site 

for hydroelectric power generation. The reservoir also serves 

as an afterbay for peak power generation at the New Colgate 

Powerhouse, which receives water from New Bullards Bar 

Reservoir on the North Yuba River (fig. 1).

The Upper Yuba River Studies Program (UYRSP), 

sponsored by the California Bay–Delta Authority (formerly 

the California-Federal Bay–Delta Program, or CALFED), 

is evaluating the feasibility of introducing anadromous fish 

species to the Yuba River system upstream from Englebright 

Dam (fig. 1). The scope of the UYRSP has six elements: 

sediment (quality and quantity), water quality, habitat, flood 

risk, water supply and hydropower, and socio-economics; the 

U.S. Geological Survey (USGS) is responsible for the technical aspects of the sediment and water-quality elements of the 

program. To achieve the UYRSP objective of fish passage at 

Englebright Dam, management scenarios under consideration 

include lowering or removing the dam. Any reduction in 

size of the dam would result in some change in the sediment 

regime of the lower Yuba River and could cause the release of 

sediment stored in Englebright Lake. This increased sediment 

load could exacerbate existing physical and chemical hazards 

in the lower Yuba River area. Sediment deposition could raise 

riverbed elevations and therefore increase flood risk in the 

valley around Marysville (fig. 1). Because much of the stored 

material is likely derived from historical gold mining areas in 

the Yuba River watershed (James, 2005), it may contain high 

concentrations of mercury (Hg) and other heavy metals that 

were lost during gold mining and recovery operations (Alpers 

and Hunerlach, 2000; Ashley, 2002; Alpers and others, 2005a, 

2005b).

The release of Hg-rich sediment from Englebright Lake 

could increase the amount of Hg available for bioaccumulation in downstream areas. The ability to predict accurately the 

fate and transport of the material stored in Englebright Lake is 

critical to assessing the feasibility of various dam-management 

scenarios. This report presents data from two 2002 sedimentsampling campaigns undertaken by the USGS to characterize 

the three-dimensional distribution of mercury, methylmercury, 

and other constituents in sediments trapped in Englebright 

Lake, and the current potential for active methylmercury production in vertical sediment profiles.

Previous Work and Related Investigations

A previous report as part of the UYRSP describing reservoir bathymetry and pre-dam Yuba River topography (Childs 

and others, 2003) concluded that, in 2001, Englebright Lake 

contained 21,890,000 m3 (cubic meter) of material deposited since the completion of Englebright Dam, reducing the 

original storage capacity (85,970,000 m3) by 25.5 percent. 

Details of a deep coring campaign conducted in May–June 

2002 by the USGS were documented by Snyder and others 

(2004a), who also presented data on the moisture content and 

bulk density of reservoir bed sediment. Results of grain-size 

distribution and loss-on-ignition (a proxy for organic content) 

analyses for subsamples from the deep coring campaign and 

a shallow coring campaign conducted in October 2002 were 

provided by Snyder and others (2004b). Using the data for 

grain-size distribution, density, and loss on ignition derived 

from the deep cores and shallow subsamples, Snyder and others (2004c) quantified the mass, organic content, and grainsize distribution of Englebright Lake sediments. Two distinct 

extrapolation methods yielded nearly identical estimates of the 

mass of the reservoir deposit: 26 × 106 metric tons, of which 

64.7–68.5 percent is sand (0.063–2 mm [millimeter]) and 

gravel (coarser than 2 mm). 

The sedimentation rate for Englebright Lake is high 

compared with that for many other lakes and reservoirs. A 

prograding delta near the middle of the lake has accumulated 

sediment up to 32.8 m (meter) thick over the 61-year history 

of the reservoir, or an average of more than 0.5 m/yr (meter 

per year). Near Englebright Dam, where the grain-size distribution is dominated by silt, the overall accumulation during 

1941–2002 was about 6 m, for an average accumulation rate 

of about 0.1 m/yr. In comparison, much lower sedimentation rates, ranging from 0.004 to 0.066 m/yr, were reported 

by Van Metre and others (2001) for 3 lakes and 8 reservoirs 

located throughout the United States. Sedimentation rates in 

Englebright Lake are also higher than those in each of 56 U.S. 

lakes and reservoirs cored by the USGS during 1992–2001 

(Van Metre and others 2004). Snyder and others (2004c) 

computed a maximum basin-wide sediment yield of 340 

metric t/km2/yr (tonne per square kilometer per year) over the 

61-year history of Englebright Lake, assuming no contribution from upstream parts of the watershed impounded by other 

dams such as Spaulding Dam and Milton Dam (fig. 1). A 

conceptual model for erosion and sedimentation in the upper 

Yuba River watershed was presented by Curtis and others 

(2005). Less than 5 percent of Englebright Lake sedimentation can be accounted for by mass wasting on hill slopes in 

2 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
the Middle Yuba River and South Yuba River, two of the three 

main tributaries to Englebright Lake. In the third main tributary, the North Yuba River, transport of coarse sediment has 

been blocked since the construction of New Bullards Bar Dam 

in 1970. Licensed hydraulic mining during 1893–1950 (James, 

2005) can account for an additional 10 percent of Englebright 

Lake sedimentation (Curtis and others, 2005). The remainder 

(more than 85 percent) is thought to be primarily from remobilization of sediment stored in active and semi-active channels; 

much of this stored sediment is from unregulated hydraulic 

mining of placer gold deposits in the watershed from the early 

1850s through 1884 (Curtis and others, 2005). 

Wolf Cr

Bear R

Bear R

121°30' 121°15' 121°00' 120°45' 120°30'

39°15'

39°30'

39°45'

0 5 10 Miles

0 5 10 Kilometers

 Lake

Oroville

Englebright

 Lake

New

Bullards Bar

 Reservoir

Our House

Dam

Log Cabin

 Dam

Scotchman

 Creek

 Dam

 Lake

Spaulding

 Milton 

Reservoir

 Jackson Meadows

 Reservoir

Yuba River

Deer Creek

Feather

Feather R

River

North

Fork

North Yuba R

South Yuba R

Dam

Yuba River watershed 

 boundary

Hydraulic mine

North Yuba

Subwatersheds

Middle Yuba

South Yuba

Stream channel

Sediment and stream dis-

 charge gaging station 

EXPLANATION

 Yuba 

goldfields

 San 

Francisco

 Los

Angeles

Central

Valley

 Area 

of map

Sierra Nevada

South Fork Feather R

Middle Fork Feather R

Grass Valley

Nevada City

Washington

Allegheny

Marysville

Area of 

figure 2

Area of 

figure 2

Middle Yuba R

New Colgate

Powerhouse

Major gold mine (hard rock) 

Figure 1. Location of Englebright Lake in the Yuba River watershed, California.

Introduction 3
The effect on sediments of legacy contamination associated with historical hardrock gold mining is also an issue in 

the Yuba River watershed. Hardrock mining in the Mother 

Lode gold belt was concentrated in the vicinity of Grass Valley 

and Nevada City and also in the Alleghany District (Clark, 

1963; Alpers and others, 2005b). Some of the largest hardrock 

mines in the Grass Valley and Nevada City areas do not drain 

into tributaries of Englebright Lake; the Grass Valley area 

drains primarily into Wolf Creek, a tributary of the Bear River 

(fig. 1), and the Nevada City area drains primarily into Deer 

Creek, a tributary to the Yuba River downstream of Englebright Dam (fig. 1). However, some of the hardrock mines 

near Nevada City, such as the Davis and Hoge mines on Little 

Rock Creek and the Ancho Erie mine on Poorman Creek, 

drain into the South Yuba River. The Alleghany mining district 

is located primarily within the Kanaka Creek subwatershed, 

which drains into the Middle Yuba River, a tributary to Englebright Lake (fig. 1). In general, mill tailings from hardrock 

gold mines of the Sierra Nevada may contain elevated concentrations of mercury that was added to enhance gold recovery 

by amalgamation at stamp mills (Churchill, 2000; Ashley, 

2002). These tailings may also contain naturally occurring 

concentrations of trace elements such as arsenic, antimony, 

and lead (Ashley, 2002). Historical mining practices included 

depositing mill tailings directly into streams or capturing tailings in impoundments, some of which remain prone to failure 

during large storm events (Ashley, 2002). 

The bioaccumulation of mercury in aquatic organisms, 

including invertebrates and fish, is most elevated in the portions of the northern Sierra Nevada that are affected by historical gold mining (Slotton and others, 1997, 2004; Alpers and 

Hunerlach, 2000; Alpers and others, 2004a, 2005b). Data for 

mercury bioaccumulation in sport fish from a reconnaissance 

sampling by the USGS of Englebright Lake and other water 

bodies in the Yuba River and Bear River watersheds were 

published by May and others (2000). These data led the State 

of California to issue an advisory that recommends limited 

consumption of smallmouth bass in Englebright Lake (Klasing 

and Brodberg, 2003). Results of additional studies of mercury 

bioaccumulation in fish and zooplankton from Englebright 

Lake and in fish and invertebrates from stream sites in South 

Yuba, Middle Yuba, and lower Yuba Rivers (Slotton and 

others, 2004) are part of the UYRSP Water Quality scope of 

work and will be published in separate reports. An additional 

component of the UYRSP Water Quality work involved USGS 

monitoring of mercury and methylmercury concentrations 

and other water-quality parameters in the main tributaries to 

Englebright Lake and the Yuba River below Englebright Dam 

(Alpers and others, 2004b) during 2001–04. Load calculations 

and mass balances of mercury and methylmercury with regard 

to Englebright Lake based on the water-quality monitoring 

will be published separately.

Downstream of Englebright Dam, the lower Yuba River 

is considered to be a critical habitat for endangered aquatic 

species, including steelhead trout (Oncorhynchus mykiss) and 

spring-run Chinook salmon (O. tshawytsha) (National Marine 

Fisheries Service, 2005). A USGS investigation (Hunerlach 

and others, 2004) characterized the concentrations of mercury 

and methylmercury, mercury methylation potential, and the 

grain-size distribution of sediment trapped behind Daguerre 

Point Dam in the Yuba Goldfields area (fig. 1), which was 

affected by deposition of hydraulic mining debris and subsequent dredging of placer gold deposits. Resource management issues at Daguerre Point Dam are similar to those at 

Englebright Dam because removing or modifying either dam 

to improve anadromous fish passage may disturb the sediments contaminated with mercury from historical gold mining 

(California Department of Water Resources, 2003). Although 

concentrations of methylmercury in sediments trapped behind 

Daguerre Point Dam were low, moderately elevated concentrations of total mercury were found in fine-grained sediment 

fractions (Hunerlach and others, 2004). The environmental 

risk associated with release of fine-grained sediment containing an elevated concentration of mercury is related to the 

potential for the mercury to be converted to the more toxic 

form of methylmercury if conditions are favorable. Aquatic 

life is exposed to methylmercury through dietary pathways, 

leading to biomagnification in the food web and potential 

harm to higher-trophic-level organisms, including humans and 

piscivorous wildlife (Wiener and others, 2003).

Purpose and Scope

The purpose of this report is to present data collected by 

the USGS on the geochemistry of sediments in Englebright 

Lake and associated information regarding data quality and 

methods of sampling and analysis. Data for subsamples of 

deep cores taken during May–June 2002 and of shallow cores 

taken during October 2002 are presented. Results for total 

mercury (HgT) analyses on 444 subsamples, methylmercury 

(MeHg) analyses on 243 subsamples, and analyses of other 

trace and major elements on 202 subsamples are presented. 

Methods used to collect, preserve, and analyze geochemical 

samples are described. Data quality is evaluated on the basis of 

analyses of replicate pairs of subsamples, standard reference 

materials, blanks, and spike additions. 

Radiolabeled mercury (203Hg(II)) was used to determine 

microbial mercury-methylation potential rates for 11 samples 

collected from three reservoir locations and various depths 

in the sediment profile. Ancillary geochemical parameters 

associated with sulfur, iron, and carbon biogeochemistry were 

assayed in these same subsamples. Basic, summary statistics 

are given regarding the spatial variation (longitudinal and 

vertical) of HgT, MeHg, and the ratio of MeHg to HgT in Englebright Lake sediments. A quantitative statistical analysis of 

the relationships between grain-size distribution and concentrations of HgT

, MeHg, loss on ignition, and other sediment 

properties will be published separately.

4 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Acknowledgments

Funding for this project was provided by the California 

Resources Agency. Terry Mills, Rebecca Fris, and Brendan 

Reed of the CALFED Bay–Delta Program and the California 

Bay–Delta Authority assisted with project management and 

coordination with a large and active stakeholder group, the 

Upper Yuba River Studies Program Workgroup. John Clerici 

of Circlepoint, Inc. (formerly Public Affairs Management) 

also assisted with stakeholder coordination. David and Carol 

Munro and the staff at Skipper’s Cove Marina assisted with 

logistical support during the coring campaigns. Rick Humphreys of the California State Water Resources Control Board 

(Sacramento, California) assisted with field work. The following staff members of the USGS (including contract employees 

through the California State University Sacramento Foundation) assisted with chemical and physical analyses of sediment 

samples: Jennifer Agee, Carlin Dare, Heather Harms, Hillary 

Harms, Le Kieu, Gary Schneider, and Ryan Wooley (Menlo 

Park, California); Dale Peart, Terry Plowman, David Roth, and 

Howard Taylor (Boulder, Colorado); and David 

Krabbenhoft, Mark Olson, and Shane Olund (Middleton, Wisconsin). The staff of the Battelle Marine Sciences Laboratory 

(Sequim, Washington) assisted with analyses of total mercury 

and methylmercury.

Reservoir Sampling

The sample locations for the deep and shallow coring 

campaigns of 2002 are shown in figures 2 and 3. For additional 

information on sampling locations, sample numbering conventions, and core handling, see Snyder and others (2004a). 

Several series of subsamples were taken from the deep cores 

(table 1). Details are provided below regarding subsampling 

methods and the handling and preserving of subsamples prior 

to analysis.

Deep Coring Campaign

The deep coring campaign was conducted on the 

DOSECC (Drilling, Observation, and Sampling of the Earth’s 

Continental Crust, http://www.dosecc.org/) research drilling 

company’s GLAD200 rig (Global LAke Drilling, 200-m maximum depth of water plus sediment), mostly using a hydraulic-piston apparatus that was advanced 3 m per run (Snyder 

and others, 2004a). Cored sediment was recovered in clear, 

plastic liners approximately 7 cm (centimeter) in diameter. 

Deep coring penetrated the full thickness of material deposited 

after 1940 at six locations in the reservoir; the cores reached a 

maximum depth of 32.8 m below the reservoir floor (Snyder 

and others, 2004a). Cores were cut into sections 1.5 m or less 

(depending on recovery) in length and capped at both ends 

on the drilling platform. Core depths were recorded relative 

to a fixed reference datum, the elevation of the Englebright 

Dam spillway (160.60 m above sea level), as explained by 

Snyder and others (2004a). Cores were kept chilled until 

splitting, which was done at the USGS laboratory in Menlo 

Park, California. Before splitting, multi-sensor logging was 

done to determine compressional wave (p-wave) velocity, wet 

bulk density, and magnetic susceptibility (Snyder and others, 

2004a). After splitting down the long axis, a dual-blade cutting tool was used to slice the liner, and then a thin wire was 

drawn through the core section to separate the unconsolidated 

sediment into two halves. The two halves were then assigned 

for working and archive purposes. The archive half of each 

section was photographed in 30-cm lengths using a digital 

camera.

Immediately after splitting, the working half of the core 

was subsampled to determine values for parameters that can 

change with exposure to the air. These parameters included 

moisture content (Snyder and others, 2004a) and methylmercury concentration (this report). The MEM (MEthylMercury) 

series of subsamples was taken for the primary purpose of 

methylmercury analysis. In representative core sections from 

a range of depths at each sampling location, 1 or 2 subsamples 

were taken for the MEM series by removing a series of sediment plugs from the cores using an ~1-cm diameter syringe 

over an ~10-cm interval. Care was taken to subsample material 

at least ~0.5 cm from the core liner to avoid the effects of 

post-coring chemical reactions (such as iron oxidation) that 

could have occurred in the sediment in contact with the liner. 

Subsamples were divided in half and stored in pre-cleaned, 

acid-washed, glass jars (Environmental Sampling Supply, Inc., 

Oakland, Calif., model PC0125). The half of the subsample 

that was collected for analysis of methylmercury and total 

mercury was frozen immediately. The other half was chilled 

and used for analysis of grain-size distribution and loss on 

ignition (results reported by Snyder and others, 2004b). 

At each coring location, 2 to 5 boreholes were cored to 

retrieve a continuous section of the stratigraphy, despite material lost between core pushes (Snyder and others, 2004a). With 

the exception of site 2 in the upper reservoir area, drilling at 

each location penetrated to the pre-reservoir surface digitized 

from topographic maps provided by the U.S. Army Corps of 

Engineers (Childs and others, 2003). Direct evidence of reaching the pre-reservoir surface was the recovery of very coarse 

(cobble-sized) material from the pre-dam river bed (Childs 

and others, 2003; Snyder and others, 2004a). After the initial 

logging and description phase was completed for most of the 

core sections, the core depth estimates were refined, and then 

resulting stratigraphy for each hole was graphed and plotted. 

This working stratigraphy provided a structure for a composite 

subsampling scheme that sought to retrieve a set of material 

that was as continuous as possible. This material was termed 

the Y series of subsamples (for example, the series collected 

at site 1 from boreholes 1A, 1B, 1C, and 1D was 1Y). Each 

subsample included about 10–100 cm of material. These 

subsamples were collected using a U-shaped channel sampler 

having a 1-cm2 or 4-cm2 cross-sectional area. The channel 

sampler was made from white Delrin®, an acetal 

Reservoir Sampling 5
 Table 1. Basic data for sediment sample series from Englebright Lake, California, 2002. 

[Sample series, data series presented in this report (short series name in parentheses). Sample ID range, sample identification numbers used in laboratory, often listed downstream to upstream, which can differ from numerical order (figure 2). Table number, mercury (Hg) and methylmercury data in tables 2–4; mercury methylation potential data in table 8; trace element data in table B5; data for heavy mineral concentrates in tables C1–C4. Number of samples does not include replicate analyses; see table numbers shown for replicate analyses. LOI, loss on ignition; b, data published by Snyder and others (2004b); t, data in this report; —, not determined]

Sample series

Deep (D) or 

shallow (S)

cores

 Sample ID range

 (numerical)

 Table 

number

 Number of samples analyzed 

 LOI 

 analysis 

Grain-size

distribution

analysis

for

 mercury

for 

methylmercury for trace elements

Continuous composites (Y series) 

D 1Y-1 to 9Y-39 2, B5 202

— 202 b b

Methyl-Hg & total Hg analysis (MEM series) 

D GS 1 to GS 166 3 166 166

— b b

October 2002 box cores S GS 200 to GS 282 4 76 77

— b b

Methylmercury production (MP series) D, S 1C-mid to 9A-bottom 8 —

—

— b b

Large-volume integrated samples (heavy mineral 

concentrates)

D 2-upper to 9-lower C1–C4

—

—

—

— t

 Totals 444 243 202

6 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
homopolymer. The length of each individual subsample was 

determined by the stratigraphic layering. Each subsample 

was divided into at least two splits, which were placed in 

pre-cleaned glass jars and chilled. One split was used for 

analysis of grain-size distribution and loss on ignition (Snyder 

and others, 2004b). The other split was used for geochemical analysis of total mercury, other trace elements, and major 

elements (this report). As a quality-control check, we collected 

additional material from selected intervals to make replicate 

subsamples (labeled “1 of 2” and “2 of 2”) for each type of 

analysis. 

The first step in the Y-series subsampling from each 

coring location was generally to identify a “master” borehole that included the most complete recovery. This borehole 

was used for subsampling as much as possible to minimize 

the uncertainty created by hole-to-hole correlations. The 

first subsample collected from each coring location was the 

uppermost material recovered, as indicated by the properties 

of the material (usually fine grained, poorly consolidated, and 

high water content) and the core depths. The subsampling 

then continued in the same core whenever possible, shifting to 

adjacent boreholes when needed to fill in gaps in the “master” borehole, to ensure a record as continuous as possible. 

These shifts were based upon direct, visual correlations of the 

stratigraphy whenever possible and the estimated core depths 

in some cases where the visual correlations could not be made 

with confidence. Rarely, short gaps in the series of subsamples 

were unavoidable due to incomplete recovery of a stratigraphic 

unit from all of the parallel holes. At the base of each coring 

location, an effort was made to include the lowermost material 

recovered, generally based on the core-depth estimates. After 

subsampling was completed for each coring location, the depth 

interval for each subsample was computed on the basis of the 

“master” hole that contained the majority of the material.

Y-series subsamples from location 4 (labeled 4Y-1 

through 4Y-34) were analyzed in their entirety (without 

sieving) for total mercury, other trace elements, and major 

elements. To achieve homogeneity, subsamples first were 

crushed using a tungsten-carbide ball mill and then were split 

using a stainless-steel sediment-splitting device. Because of 

the relatively coarse grain size in cores from the upper part 

of the reservoir (sites 7, 8, and 9; fig. 2), Y-series subsamples 

from these locations were sieved using a nylon screen with 

an opening size of 0.06 mm, and only the silt- and clay-sized 

material that passed through the screen was analyzed. Y-series 

subsamples from the site nearest Englebright Dam (site 1) 

were also sieved so that the chemistry of the silt-and-clay fraction could be compared with that at the sites in the upper part 

of the reservoir.

Six subsamples used to determine potential rates of methylmercury production (or Hg Methylation Potential [the MP 

series]) were taken from deep cores (2–25 m below reservoir 

floor). Two subsamples each were taken from sites 1, 4, and 9 

(fig. 2). To our knowledge, these samples represent the deepest 

sediment depths for which microbial mercury transformations 

have been examined in any system to date.

Bulk samples used to prepare heavy mineral concentrates 

and to estimate gold content consisted of samples from four 

of the deep coring locations, focusing on the upstream part of 

the reservoir (sites 5/7, 9, 3/8, and 2; fig. 2). Relatively large 

volumes of sediment were necessary because of expected 

inhomogeneity (the “nugget effect”). The working halves of 

several split-core sections were combined to make each composite sample, integrating representative parts of the reservoir 

stratigraphy. Three composites representing the upper, middle, 

and lower parts of the reservoir deposit were prepared from 

samples taken at each of two locations (sites 5/7 and 3/8); 

two composites representing the upper and lower parts of the 

deposit were prepared at site 9; and a single composite representing the upper part of the deposit at site 2 brought the total 

number of composite samples to nine. (For additional details, 

see Snyder and others, 2004a.)

Shallow Coring Campaign

At each shallow coring location (fig. 3), box cores and 

gravity cores were collected. The box cores were used for 

geochemical subsampling and the gravity cores were used for 

mapping of stratigraphic properties. Sampling and processing were done from a pontoon boat. Samples were box cored 

using an Eckman dredge, a stainless-steel box 30 cm on each 

side, which penetrated about 6 to 20 cm into the sediment 

and provided an undisturbed sample of the sediment-water 

interface. Immediately after collection, subsamples were 

taken from each box using 7-cm-diameter clear polycarbonate 

(Lexan®) core tubes. A plunger apparatus was inserted into 

the bottom of each core tube and the sediment was pushed 

toward the top, expelling the overlying water. The core tubes 

were capped temporarily and transferred to a glove bag filled 

with inert gas (nitrogen, N2). Inside the glove bag, material 

was pushed through the top of the core tube in intervals of 

1 cm, 2 cm, or 4 cm. A polycarbonate ring of the appropriate 

length was placed on the top of the core tube. Once the material filled the ring, an acid-cleaned plastic sheet was used to 

separate the material in the ring from the rest of the sediment 

core. The material above the plastic sheet was then transferred 

to a pre-cleaned glass jar (60 mL), in which the sample was 

homogenized with a plastic spatula and from which split 

subsamples were removed. One of these split subsamples was 

frozen immediately after collection and used for analysis of 

methylmercury and total mercury. Another split subsample, 

subsequently analyzed for grain-size distribution and loss 

on ignition (Snyder and others, 2004b), was stored chilled. 

Additional subsamples were taken for the purpose of analyzing radioisotopes, including 7

Be, 137Cs, and 210Pb, the results of 

which will be reported separately.

Reservoir Sampling 7
39

39

°18'

°16'

121° 16' 121° 14' 121° 12' 

Deep coring average site locations (May–June 2002) 

1

6

4

7

9 8 3

2

2

5

11A–F

17

13

14

Shallow core samples (October 2002)

Detail in figure 3

15

15

10A–G 16

23A, 23B, 18 12A–E 19

Englebright

Dam

A

B

C

D

E F

G

0 2 Miles

0 2 Kilometers

A

Figure 2. Locations of deep and shallow coring, Englebright Lake, California. Modified from Snyder 

and others (2004b).

8 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
N

Deep coring boreholes (May–June 2002) 

Shallow core samples (October 2002)

11E 11D 11C 11G

11B

11A

11F 13

10G 10F 16

12E

12D

12C

12B

12A

19

19

10E

10D 10C

10B

10A

1B 1A 1D 1C

6E

6F 6A

6B

6C

6D

4D 4B

4C 4A

5A

7C

7B

7A

9A 9B

9C

3B

3C

3C

3D

3A 8B, 8C

8A

2A

2B

A B

C D

E F

G

EXPLANATION

0 0.2 Mile

0 0.1 0.2 Kilometer

0.1

Figure 3. Detailed maps of sampling locations at Englebright Lake, California. See figure 2 for location of each box. 

Modified from Snyder and others (2004b).

Reservoir Sampling 9
Shallow sediment subsamples used to determine potential 

rates of mercury methylation were taken from 0–4 cm below 

the reservoir floor at three shallow sites (10, 11, and 12) and 

4–8 cm at two sites (10 and 11). These shallow sites were 

located close to sites 1, 4, and 9 (figs. 2 and 3) where subsamples had been taken for similar analysis from deep cores. 

Methods of sample collection and processing were identical to those described for the other shallow samples with the 

exception that larger (500 mL) glass jars were used and they 

were filled to the top to exclude oxygen. For these five shallow mercury-methylation subsamples, ancillary geochemical 

parameters were assayed: microbial sulfate reduction rates, 

sulfur speciation (sediment acid volatile sulfide, total reduced 

sulfur, and pore-water sulfate), iron speciation (sediment acid 

extractable iron(II), amorphous iron(III), crystalline iron(III), 

and pore-water iron(II)), pore-water chloride, and dissolved 

organic carbon. 

Laboratory Methods 

Laboratory methods were chosen on the basis of past 

laboratory performance and data-quality objectives for the 

present study. Total mercury, methylmercury, trace and major 

elements, and mercury methylation potential were analyzed, 

and heavy minerals were identified. Concentrations of mercury, methylmercury, and trace metals in sediment are reported 

on a dry basis throughout this report.

Total Mercury

Total mercury (HgT) in sediment was analyzed by two 

different laboratories for this study: the USGS laboratory in 

Boulder, Colorado (USGS-Boulder), and the Battelle Marine 

Sciences Laboratory (BMSL) in Sequim, Washington. The 

Y-series subsamples were analyzed by the USGS-Boulder laboratory; the MEM series from the deep cores and the shallow 

core subsamples were analyzed primarily by the BMSL. As 

a check on quality control at the BMSL, fifteen split subsamples from the MEM series were also analyzed by the USGS 

Wisconsin District Mercury Laboratory (USGS-WDML) in 

Middleton, Wisconsin.

The USGS-Boulder laboratory analyzed HgT in sediment 

using cold-vapor atomic fluorescence spectrometry (CVAFS) 

after digestion using a mixture of distilled nitric, hydrochloric, and hydrofluoric acids in a closed Teflon® bomb (Hayes, 

1993). Mercury stock and standard solutions were made 

from Puratronic grade (99.9995 percent) mercuric chloride 

(HgCl2) salt (Johnson Matthey Public Limited Company) and 

preserved in a solution of high-purity nitric acid and primarystandard grade potassium dichromate. Deionized (DI) water 

(American Society for Testing and Materials [ASTM] type 1, 

18 MΩ-cm [megaohm-centimeter]) was used for preparing all 

standards and reagent solutions. A solution of 3-percent hydrochloric acid (volume:volume, hydrochloric acid:DI water) 

was used to prepare a 2-percent stannous chloride (SnCl2) 

solution (wt:volume, stannous chloride:3-percent hydrochloric acid), which was used to reduce mercury to its elemental 

form in the cold vapor reactor. The vapor was transported to 

the detector using a stream of argon gas. Trace concentration 

levels of mercury were measured using an automated CVAFS 

analyzer (PS Analytical) using methods described previously 

(Roth,1994; David A. Roth, U.S. Geological Survey, written commun., 1999). Instrumental parameters for the CVAFS 

mercury analysis were the same as those described by Alpers 

and others (2000). Peak-height intensities of unknown samples 

were compared to a six-point calibration curve prepared from 

aqueous standards ranging 

in concentration from 0 to 50 ng/L (nanogram per liter), 

preserved with potassium dichromate and nitric acid.

The BMSL analyzed HgT in sediment by cold vapor 

atomic absorption spectrometry (CVAAS). The procedure 

(Lasorsa, 2003a) is a modified version of U.S. Environmental 

Protection Agency (USEPA) method 245.5 (U.S. Environmental Protection Agency, 1991). The USEPA method was 

modified by eliminating the use of potassium permanganate in 

the digestions because it was a source of mercury contamination. A digestion using strong acids was carried out in a closed 

Teflon bomb. Mercury ions in the digestate were reduced by 

acidic SnCl2 to Hg+ and then carried through a flow cell on a 

stream of inert gas (argon). The luminous intensity of monochromatic light that passes through the sample was compared 

with the luminous intensity of the same light that passed 

through a reference beam using a photometric detector at a 

wavelength of 253.7 nanometers. The attenuation of the light 

is directly proportional to the concentration of mercury vapor, 

which was quantified using a standard curve. Mercury stock 

standards were purchased from High Purity Standards. An 

intermediate standard with a mercury concentration of 

10 mg/L (milligram per liter) was prepared in 1 percent HCl. 

To develop the standard curves, five mercury working 

standards (typically ranging from 0.5 μg/L [microgram per 

liter] to 12.5 μg/L) were prepared by diluting the intermediate 

standard.

Methylmercury

Monomethylmercury (MeHg) in sediment was analyzed 

for this study primarily by the BMSL. (For the remainder 

of this report, “methylmercury” [also abbre­viated as MeHg] 

is used instead of “monomethylmercury”; note that other 

methylated forms of mercury such as dimeth­ylmercury may 

have been present but were not included in methylmercury 

analyses reported in this study.) As a quality assurance check, 

fifteen replicate subsamples were analyzed by the USGSWDML. MeHg can be difficult to measure in solids because 

10 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
of matrix interferences and the possibility of unintentionally 

producing MeHg during distillation (Bloom and others, 1997; 

Hintelmann and others, 1997; Hammerschmidt and Fitzgerald, 2001). Therefore, extraction methods using methylene 

chloride (CH2Cl2) were used by both laboratories to minimize 

MeHg artifacts.

At the BMSL, MeHg in sediment was analyzed by 

CVAFS using a procedure (Lasorsa, 2003b) based on Bloom 

(1989) and equivalent to USEPA method 1630. A minimum 

of 200 mg (milligrams) of sediment was placed in a 50-mL 

(milliliter) centrifuge tube along with 5 mL of acidic potassium bromide (KBr) solution, 1 mL of 1 molar copper sulfate 

(CuSO4), and 10 mL of CH2Cl2. After one hour of vigorous shaking, the samples were centrifuged for 30 minutes at 

2,000 rpm (revolutions per minute). Immediately after centrifuging, 2 mL of the CH2

Cl2 layer was transferred by pipette 

into a distillation vial along with 45 mL of reagent water. The 

distillation vial was capped and placed in a heating block and 

connected to N2 carrier gas flowing at 60 mL/min (milliliter 

per minute). The block was heated to 45°C until all of the 

CH2Cl2 evaporated. The pH was adjusted to 4.9 (to maximize 

ethylation potential) using acetate buffer. The sample was then 

reacted with an ethylating reagent for 17 minutes, after which 

the sample was purged with argon into a Carbotrap (Supelco, 

Inc.). Methyl-ethylmercury that resulted from the ethylation 

of methylmercury in the sample was then quantified using 

CVAFS.

Methylmercury in sediment was analyzed at the USGSWDML by inductively coupled plasma mass spectrometry 

(ICP–MS) using extraction methods very similar to those used 

at the BMSL. The extraction methods used at the WDML 

are described by DeWild and others (2004), who adopted the 

technique of Hintelmann (1999) for extracting MeHg from 

solids to eliminate formation of MeHg in samples containing 

high inorganic mercury levels. Solids (0.5 to 1.0 g [gram]) 

were placed into a centrifuge tube to which 5 mL of acidic 

KBr solution, 1 mL of 1 molar CuSO4, and 10 mL of CH2Cl2

were added sequentially. The mixture was allowed to react for 

an hour and then was shaken for an hour to ensure complete 

extraction of the MeHg. Following the shaking, the samples 

were centrifuged to break any emulsion that had formed. An 

aliquot of 2 mL of the CH2Cl2 was cleanly transferred to a vial 

containing reagent water. Each vial was placed in a heating 

block until all CH2Cl2 evaporated and the MeHg was extracted 

back into the reagent water. The pH of the extractant was 

adjusted to 4.9 (to maximize ethylation potential) using acetate 

buffer. The extract then was ethylated using sodium tetraethyl 

borate (NaBEt4) and allowed to react for 15 minutes. After the 

reaction, the extractant was purged with N2 gas for 20 minutes, 

and the ethylated forms of Hg were collected on a sample trap 

containing Carbotrap (Supelco, Inc.). The ethylated Hg species were desorbed thermally from the sample trap, separated 

using a gas chromatographic (GC) column, reduced using a 

pyrolytic column, and quantified using inductively coupled 

plasma–mass spectrometry (ICP–MS). Deionized water blanks 

were analyzed as part of each analytical batch; reported results 

were blank-corrected.

Trace and Major Elements

Trace and major elements in sediments from the Y-series 

subsamples were analyzed using inductively coupled plasma 

(ICP) methods by the USGS-Boulder laboratory. Both atomic 

emission spectroscopy (ICP–AES) and mass spectrometry 

(ICP–MS) were used. Sediments in subsamples collected for 

analysis of trace and major elements were completely dissolved using an HCl–HNO3

–HF acid, microwave, total-digestion procedure (Hayes, 1993). The digested subsamples were 

diluted at 1:10 (volume:volume, digest:DI water) with 

18 MΩ-cm DI water and were preserved with distilled nitric 

acid. Major elements, including calcium (Ca), iron (Fe), 

magnesium (Mg), potassium (K), sodium (Na), and sulfur 

(S), were determined by ICP–AES techniques using a PerkinElmer Optima 3300DV multi-channel emission spectrometer. 

Using the dual-view (radial and axial) optical configuration 

provided optimal sensitivity for various elements regardless 

of concentration. A description of the ICP–AES analysis 

conditions and procedures is given by Garbarino and Taylor 

(1979). Details of the operational conditions are described 

by Mitko and Bebek (1999, 2000). Concentrations of trace 

elements other than mercury were determined by ICP–MS 

using a Perkin Elmer Elan Model 6000. Aerosols of acidified 

aqueous samples were introduced into the spectrometer with 

a cone-spray pneumatic nebulizer. Multiple internal standards 

(indium, iridium, and rhodium), which covered the mass 

range, were used to normalize the system for drift. Details of 

the specific analysis techniques, procedures, and instrumental 

settings are described by Garbarino and Taylor (1996) and 

Taylor (2001). 

Mercury Methylation Potential 

Standard radiotracer methods were used to measure 

potential rates of microbial MeHg production, Hg(II) methylation, at the USGS laboratory in Menlo Park, Calif. 

(Marvin-DiPasquale and others, 2003). An amendment 

containing 1.5 μCi/100 μL (microcurie per 100 microliters) 

of radiolabeled divalent mercury 203Hg(II), having a half-life 

of 46.5 days, was used for the MeHg-production rate assay. 

The 203Hg(II) specific activity of the injection solution was 

1.15 mCi/mg (millicurie per milligram), which resulted in 

a total Hg(II) amendment of 436 ng/g (nanogram per gram) 

wet sediment per 3.0-g sediment subsample. Sample sets 

for each interval assayed for microbial Hg(II)-methylation 

potential consisted of duplicate, live (incubated) samples and 

one control sample in which microbes were killed by flash 

freezing at the beginning of the experiment (time zero). MeHg 

production sample sets were incubated for 4 hours at 12–16°C 

for shallow subsamples or for 24 hours at 19°C for deep subsamples. It was assumed that the Hg(II)-methylation process 

Laboratory Methods 11
was first-order for the purposes of calculating potential rates 

(Marvin-DiPasquale and others, 2003). Potential rates were 

subsequently calculated as the prod­uct of the radiotracerderived rate constant and the final con­centration of radiotracer 

amendment in the whole sediment, and were thus independent 

of the amount of Hg(II) that might have been present originally in each subsample.

The five shallow sediment samples that were assayed 

for Hg(II) methylation potential were also subsam­pled to 

determine several ancillary chemical parameters, including 

microbial sulfate reduction, pH, oxidation-reduction (redox) 

potential, loss on ignition, acid volatile sulfide, total reduced 

sulfur, and iron speciation. Sulfate-reduction samples were 

subsampled and incubated in a manner analogous to that for 

the mercury methylation rate assays, including replicates consisting of two live (incubated) and one killed control sample 

per site and depth. Samples were amended with 1.0 μCi/sample of carrier-free 35SO4

2- and assayed according to Jørgensen 

(1978). The pH and redox potential were determined by inserting an electrode directly into sediment. Weight loss on ignition 

was measured as a proxy for organic content (American Public 

Health Association, 1981). Two forms of sulfur—acid volatile 

sulfide and total reduced sulfur—were determined using 

methods described by Ulrich and others (1997). Iron speciation analyses included acid-extractable Fe(II), acid-extractable 

amorphous Fe(III), and crystalline Fe(III) (Lovley and Phillips, 1987; Roden and Zachara, 1996). Organic content and 

both forms of solid-phase sulfur were measured in duplicate 

samples from each of the five shallow sediment samples. Dissolved organic carbon (DOC) concentrations were assessed 

by adding DI water (Milli-Q, ASTM type 1, 18 MΩ-cm; 

10 mL) to the sediment (10 g) to obtain enough pore water 

for analysis. The exact weight of the sediment and the water 

added per tube was recorded, and subsequent pore-water 

analyte concentrations were calculated taking this pore-water 

dilution into account. Samples were shaken until each became 

a homogenous slurry, which was then centrifuged at 3,000 rpm 

for 15 minutes in 45-cm3 polystyrene, screw-cap tubes. The 

resulting supernatant was filtered (0.45-μm nylon syringe, inline filter) inside an oxygen-free glove bag. The DOC samples 

were frozen until analy­sis, which was done using high-temperature oxidation with infrared detection (Qian and Mopper, 

1996). Pore-water sulfate samples were preserved by freezing 

under anoxic conditions and assayed via ion chromatography 

(Dionex, 1992). Pore-water iron(II) was preserved by adjusting pH to <2 with 10-percent HCl and assayed via the colorimetric Ferrozine assay (Stookey, 1970).

Heavy Minerals

Heavy-mineral concentrates were prepared for the 

composite samples by Cal Sierra Development Company in 

Marysville, California. First the material was screened using 

a 9.5-mm sieve. The material passing through the sieve was 

processed on a shaker table, yielding a concentrated sample 

of minerals with greater density, referred to as a heavy-mineral concentrate. The concentrate was then screened using 

stainless-steel sieves of the following sizes (in mm): 4.75, 

2.36, 1.18, 0.60, 0.30, 0.15, 0.075, and 0.063. The mass 

passing through each sieve was measured, and the material was retained for microscopic examination. Observations 

were made using a stereo microscope and a scanning electron microscope (SEM) with energy dispersive spectrometer 

(EDS).

Quality Assurance and Quality Control 

A variety of procedures was used to ensure high data 

quality and to quantify accuracy and precision when appropriate. Digestion blanks were prepared and analyzed to determine 

the level of contamination, if any, in the digestion equipment 

and reagents. Spikes were added to blanks and to a subset 

of the analyzed samples to ensure that analyses accurately 

measured concentrations in the range of sample matrixes 

encountered. Replicates were digested to form a subset of the 

analyzed samples to assess variability in laboratory procedures 

and analytical methods. Replicate splits taken at the time of 

initial subsampling are referred to as core replicates, whereas 

replicate splits taken at a later time by the analyzing laboratory 

are referred to as laboratory replicates. Fifteen split subsamples were analyzed for total mercury and methylmercury 

at two laboratories (BMSL and USGS-WDML) for comparative purposes. At each laboratory, standard reference materials 

(SRM) were digested along with analyzed samples; results 

from analysis of SRMs were compared with certified values to 

determine analytical accuracy.

Total Mercury

Quality-assurance analyses of SRMs for total mercury 

(HgT) at two of the laboratories used in this study (table A1) 

indicate a high level of accuracy and low variability. The 

USGS-Boulder laboratory used NIST 2704, Buffalo River 

Sediment, provided by the National Institute of Standards and 

Technology. For this SRM, 24 of 27 analyses were within the 

range of 85 to 115 percent of the certified value, and the average was 101 percent. The BMSL used IAEA-356, provided by 

the International Atomic Energy Agency. For IAEA-356, all 

14 analyses were within the range of 98 to 113 percent of the 

certified value; the average was 103 percent.

Other quality-assurance procedures used by the USGSBoulder laboratory and the BMSL in conjunction with their 

HgT determinations included analyses of blanks and spike 

additions. Two types of spikes were prepared, one by adding a 

known amount of Hg to blanks (referred to as blank 

spikes) and the other by adding a known amount of Hg to 

environmental samples that were previously analyzed (referred 

to as matrix spikes). 

12 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
At the BMSL, three laboratory blanks were analyzed with 

each of the 12 batches of samples. Total mercury was detected 

in only 3 of the 36 blanks. In those 3 blanks, the detected 

HgT concentrations were less than 10 ng/g, which is twice the 

method detection limit (MDL) of 5 ng/g. Three of the environmental samples had HgT concentrations less than the MDL, 

whereas most of the samples had concentrations more than 

10 times greater than the MDL. Because of the small number 

of laboratory blanks with detected concentrations of HgT at 

the BMSL, the data were not blank-corrected (a procedure in 

which the amount detected in laboratory blanks is systematically subtracted from the results for environmental samples). 

A total of 28 blank spikes were analyzed at the BMSL for 

HgT. Recoveries ranged from 43 to 103 percent; the average 

value was 91.8 percent and the median value was 97.5 percent. 

Three blank spikes that were originally outside the laboratory’s data quality objective (75 to 125 percent recovery) were 

reanalyzed, according to the laboratory’s standard operating 

procedure, and all but one met the laboratory’s data-quality 

objectives. 

Twenty-five pairs of HgT matrix spikes and matrix spike 

replicates were analyzed by the BMSL with the samples. 

Recoveries for these matrix spikes ranged from 92 percent to 

107 percent for HgT, within the laboratory’s data-quality objectives. Variability between replicates is described using Relative 

Percentage Difference (RPD), defined as the 100 times the 

absolute value of the difference between two concentrations 

divided by their average. The RPD between the matrix spikes 

and matrix spike replicates ranged from 0 to 8 percent, well 

within the laboratory’s data-quality objective (RPD values less 

than 25 percent).

The USGS-Boulder laboratory and the BMSL analyzed 

a total of 40 pairs of replicate subsamples for HgT; 31 pairs 

were laboratory replicates and 9 pairs were core replicates 

(table A2). Each pair of replicate analyses represented two 

separate digestions of sediment, so variations in results could 

have been caused by sample inhomogeneity as well as variability in the analytical determinations. Median values of 

RPD were 5.8 percent for the 31 laboratory replicates and 

13.2 percent for the 9 core replicates. The USGS-Boulder 

laboratory determined the concentrations of HgT by analyzing 

each digested Y-series subsample three times and computing 

the average; the concentrations and standard deviations are 

given in table 2. The standard deviations were typically less 

than 2 percent of the average concentrations.

An additional check on data quality is provided by the 

analyses of HgT in 15 split subsamples that were analyzed by 

the BMSL and the USGS-WDML. The median of the 15 RPD 

values for HgT was 11.1 percent, and 12 of the 15 RPD values 

were less than 15 percent (table A5). RPD values for the other 

three subsamples were 17, 53, and 109 percent. A correlation 

plot showing results of the HgT analyses for these 15 split subsamples from the two laboratories (fig. A1) shows that data are 

distributed on both sides of the 1:1 line, indicating that there is 

no systematic difference in concentrations.

Methylmercury

Two SRMs for methylmercury (MeHg), IAEA-356 

and IAEA-405, were analyzed by the BMSL along with the 

samples for this study (table A3). These two SRMs were certified for MeHg by the International Atomic Energy Agency 

(Horvat and others, 1994; Wyse and others, 2004). Some of 

the laboratories participating in the certification of these SRMs 

used the distillation technique, which has since been shown 

to produce an analytical artifact resulting in inflated values of 

MeHg (Bloom and others, 1997; Hintelmann and others 1997; 

Hintelmann, 1999). Therefore, the extraction technique used 

for MeHg analysis in this study avoids the analytical artifact 

problem and is now in common use. The extraction method 

routinely produced MeHg concentrations in the range of 

65–95 percent of the certified values for the two SRMs, which 

was reasonable considering the different analytical methods; 

the laboratory’s data-quality objective is 67 to 133 percent 

recovery for MeHg in SRMs. For SRM IAEA-356, 17 of the 

18 analyses were in the range of 72–95 percent of the certified 

value, with one outlier; for SRM IAEA-356, 16 of 19 values 

for recovery were in the range of 65–91 percent of the certified 

value with three outliers. Because no more than one of the 

SRM outliers occurred within an individual batch of samples, 

these results meet the data-quality objective of the BMSL. 

A total of 21 environmental samples were analyzed in 

replicate for MeHg by the BMSL. Nineteen of the samples had 

a single replicate (two analyses), one had two replicates (three 

analyses), and one had three replicates (four analyses), bringing the total number of replicate analyses to 24 (table A4). 

The multiple replicate analyses were compared as follows: for 

the sample with two replicates (three analyses), three separate 

RPD values were calculated; for the sample with three replicates (four analyses), six separate RPD values were calculated, 

representing all possible combinations (table A4). The median 

value of RPD for MeHg in all replicates was 10.5 percent 

and the median value of RPD for the 19 laboratory replicates 

was 8.8 percent. For all but four of the samples, the RPD 

values were less than or equal to about 20 percent. The other 

4 samples showed higher variability; RPD values ranged from 

about 40 percent to about 60 percent. The BMSL’s data-quality objective for replicate analyses of MeHg requires that 

fewer than 35 percent of the replicate pairs have RPD values 

greater than 35 percent, so the results are within the objective. 

Three of the five core replicates were among the samples with 

higher RPD values, and two of these were from cores 11C-B1 

and 11C-B2. These cores were taken in separate, parallel tubes 

from the same Eckman dredge sample (box core), so they 

were not split samples in the usual sense. In contrast, the other 

core replicates were made by homogenizing material from a 

single core interval in a glass jar and then spooning half of the 

sample into a second jar. In light of the methods used for taking these samples, the higher values of RPD are more likely to 

have been caused by sample inhomogeneity than by 

laboratory error.

Quality Assurance and Quality Control 13
Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002—Continued. 

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream 

to upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram per gram; mm, millimeter; cm, centimeter; <, less than]

Sample ID Replicate Core ID

Relative sample location Total mercury

Sieved to

< 0.060 mm Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

Concentration

(ng/g, dry)

SD

(ng/g, dry)

1Y-1 1A-1H-1, 4–93 cm 60.79 61.68 0.45 468 3 Y

1Y-1A 1D-1H-1, 51–69 cm 61.50 61.68 0.81 491 2 Y

1Y-2 1D-1H-1, 69–80 cm 61.68 61.79 0.95 287 1 Y

1Y-3 1D-1H-1, 80–94 cm 61.79 61.93 1.07 208 5 Y

1Y-4 1 of 2 1D-1H-1, 94–140 cm 61.93 62.39 1.37 208 1 Y

1Y-4 2 of 2 1D-1H-1, 94–140 cm 61.93 62.39 1.37 195 3 Y

1Y-5 1D-1H-2, 0–52 cm 62.39 62.91 1.86 133 3 Y

1Y-6 1D-1H-2, 52–80 cm 62.91 63.19 2.26 139 2 Y

1Y-7 1B-2E-1, 10–33 cm 63.19 63.26 2.44 181 4 Y

1Y-8 1 of 2 1B-2E-2, 0–75 cm 63.26 63.94 2.81 202 1 Y

1Y-8 2 of 2 1B-2E-2, 0–75 cm 63.26 63.94 2.81 196 1 Y

1Y-9 1B-2E-2, 75–150 cm 63.94 64.61 3.49 218 3 Y

1Y-10 1B-2E-3, 0–80 cm 64.61 65.35 4.19 179 1 Y

1Y-11 1 of 2 1B-2E-3, 80–108 cm 65.35 65.61 4.69 366 4 Y

1Y-11 2 of 2 1B-2E-3, 80–108 cm 65.35 65.61 4.69 343 3 Y

1Y-12 1B-2E-3, 108–117 cm 65.61 65.69 4.86 196 2 Y

1Y-13 1B-2E-3, 117–150 cm 65.69 66.00 5.06 299 7 Y

1Y-14 1B-2E-6, 0–5 cm 66.00 66.05 5.24 321 5 Y

1Y-15 1B-2E-7, 0–1 cm 66.05 66.06 5.27 272 4 Y

1Y-16 1 of 2 1B-3E-1, 0–52 cm 66.11 66.63 5.58 258 4 Y

1Y-16 2 of 2 1B-3E-1, 0–52 cm 66.11 66.63 5.58 265 3 Y

1Y-17 1B-3E-1, 52–76 cm 66.63 66.87 5.96 346 3 Y

1Y-18 1B-3E-1, 76–90 cm 66.87 67.01 6.15 175 5 Y

1Y-19 1 of 3 1B-3E-1, 90–101 cm 67.01 67.12 6.28 253 4 Y

1Y-19 2 of 3 1B-3E-1, 90–101 cm 67.01 67.12 6.28 240 4 Y

1Y-19 3 of 3 1B-3E-1, 90–101 cm 67.01 67.12 6.28 251 5 Y

1Y-20 1B-3E-1, 101–110 cm 67.12 67.21 6.37 101 3 Y

1Y-21 1B-3E-6, 0–5 cm 67.21 67.26 6.45 149 2 Y

1Y-22 1B-3E-7, 0–4 cm 67.26 67.30 6.49 258 3 Y

1Y-23 1A-4E-1, 4–72 cm 67.30 67.51 6.62 343 3 Y

4Y-1 4B-1H-1, 4–24 cm 34.37 34.57 0.10 137 0 N

4Y-2 4B-1H-1, 24–70 cm 34.57 35.03 0.43 101 0 N

4Y-3 4A-1H-1, 35–73 cm 35.03 35.41 0.85 133 1 N

4Y-4 4A-1H-1, 73–110 cm 35.41 35.77 1.22 218 4 N

4Y-5 4A-1H-2, 0–27 cm 35.77 36.05 1.54 166 2 N

Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002.

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream to 

upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram 

per gram; mm, millimeter; cm, centimeter; <, less than]

14 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002—Continued. 

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream 

to upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram per gram; mm, millimeter; cm, centimeter; <, less than]

Sample ID Replicate Core ID

Relative sample location Total mercury

Sieved to

< 0.060 mm Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

Concentration

(ng/g, dry)

SD

(ng/g, dry)

4Y-6 4A-1H-2, 27–62 cm 36.05 36.40 1.86 195 0 N

4Y-7 4A-1H-2, 62–150 cm 36.40 37.27 2.47 355 6 N

4Y-8 1 of 2 4B-2H-1, 14–124 cm 37.27 38.38 3.46 225 5 N

4Y-8 2 of 2 4B-2H-1, 14–124 cm 37.27 38.38 3.46 243 2 N

4Y-9 4B-2H-2, 0–44 cm 38.38 38.86 4.25 231 1 N

4Y-10 4B-2H-2, 44–66 cm 38.86 39.08 4.60 107 1 N

4Y-11 4B-2H-2, 66–78 cm 39.08 39.20 4.77 148 1 N

4Y-12 4A-2H-3, 17–81 cm 39.20 39.84 5.15 134 2 N

4Y-13 4A-2H-3, 81–117 cm 39.84 40.20 5.65 173 1 N

4Y-14 4A-2H-4, 0–25 cm 40.20 40.45 5.96 246 5 N

4Y-15 4B-3H-1, 0–47 cm 40.45 41.06 6.39 279 0 N

4Y-16 4B-3H-1, 47–86 cm 41.06 41.57 6.95 165 1 N

4Y-17 4A-4H-1, 55–108 cm 41.57 42.10 7.47 189 4 N

4Y-18 4A-4H-1, 108–127 cm 42.10 42.38 7.87 266 4 N

4Y-19 1 of 2 4A-4H-2, 9–95 cm 42.38 43.24 8.44 251 0 N

4Y-19 2 of 2 4A-4H-2, 9–95 cm 42.38 43.24 8.44 680 8 N

4Y-20 4A-4H-2, 95–146 cm 43.24 43.75 9.13 299 4 N

4Y-21 4B-4H-1, 26–48 cm 43.75 43.89 9.45 308 6 N

4Y-22 4B-4H-1, 48–73 cm 43.89 44.04 9.60 453 13 N

4Y-23 4B-4H-1, 73–125 cm 44.04 44.36 9.83 326 5 N

4Y-24 4B-4H-1, 125–140 cm 44.36 44.59 10.11 353 5 N

4Y-25 4B-4H-2, 20–89 cm 44.59 45.01 10.43 256 1 N

4Y-26 4B-4H-2, 89–150 cm 45.01 45.39 10.83 471 6 N

4Y-27 4A-5H-2, 51–101 cm 45.39 45.86 11.26 550 4 N

4Y-28 4B-5H-1, 0–56.5 cm 45.86 46.42 11.77 315 3 N

4Y-29 4B-5H-1, 56.5–142 cm 46.42 47.26 12.47 295 2 N

4Y-30 4B-5H-2, 0–71 cm 47.26 47.97 13.25 462 3 N

4Y-31 4B-5H-2, 71–135 cm 47.97 48.61 13.92 296 3 N

4Y-32 4B-5H-2, 135–250 cm 48.61 48.76 14.32 348 0 N

4Y-33 4B-5H-6, 0–5 cm 48.77 48.82 14.43 439 4 N

4Y-34 4B-6H-1, 0–80 cm 48.93 49.70 14.95 269 2 N

7Y-02 7C-1H-1, 80–117 cm 15.13 15.50 0.98 288 1 Y

7Y-03 7C-1H-2, 0–31 cm 15.50 15.81 1.33 246 1 Y

7Y-04 1 of 2 7C-1H-2, 31–97 cm 15.81 16.47 1.81 240 8 Y

7Y-04 2 of 2 7C-1H-2, 31–97 cm 15.81 16.47 1.81 281 4 Y

Quality Assurance and Quality Control 15
Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002—Continued. 

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream 

to upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram per gram; mm, millimeter; cm, centimeter; <, less than]

Sample ID Replicate Core ID

Relative sample location Total mercury

Sieved to

< 0.060 mm Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

Concentration

(ng/g, dry)

SD

(ng/g, dry)

7Y-07 7C-2H-1, 92–150 cm 17.63 18.21 3.59 287 4 Y

7Y-08 7C-2H-2, 0–74 cm 18.21 18.95 4.25 237 1 Y

7Y-09 7A-2H-2, 29.5–66.5 cm 19.28 19.65 5.14 228 3 Y

7Y-10 7A-2H-2, 66.5–112 cm 19.65 20.10 5.55 248 4 Y

7Y-11 7C-3H-1, 46–93.5 cm 20.10 20.58 6.01 263 1 Y

7Y-12 7C-3H-1, 93.5–146 cm 20.58 21.10 6.51 258 2 Y

7Y-13 7C-3H-2, 0–52 cm 21.10 21.60 7.02 178 1 Y

7Y-14 7C-3H-2, 52–101.5 cm 21.60 22.08 7.51 123 3 Y

7Y-15 7C-3H-2, 101.5–150 cm 22.08 22.55 7.99 138 1 Y

7Y-16 7A-3H-2, 40–65 cm 22.55 22.75 8.32 114 0 Y

7Y-17 7C-4H-1, 9–52 cm 22.75 23.18 8.64 144 1 Y

7Y-20 7C-4H-3, 54–124.5 cm 24.47 25.18 10.50 276 3 Y

7Y-21 1 of 2 7A-4H-2, 29.5–73 cm 25.18 25.60 11.06 589 3 Y

7Y-21 2 of 2 7A-4H-2, 29.5–73 cm 25.18 25.60 11.06 585 1 Y

7Y-22 7A-4H-2, 73–109.5 cm 25.60 25.96 11.45 266 3 Y

7Y-23 7C-5H-1, 41.5–98.5 cm 25.96 26.52 11.91 406 3 Y

7Y-24 7C-5H-1, 98.5–140 cm 26.52 26.92 12.39 432 3 Y

7Y-25 7C-5H-2, 0–20 cm 26.92 27.11 12.69 414 4 Y

7Y-26 7C-6H-1, 0–87.5 cm 27.30 28.06 13.35 290 2 Y

7Y-27 7C-6H-1, 87.5–151 cm 28.06 28.61 14.01 448 1 Y

7Y-28 7C-6H-2, 0–78 cm 28.61 29.39 14.67 706 10 Y

7Y-29 7C-6H-2, 78–131 cm 29.39 29.92 15.33 477 4 Y

7Y-30 7C-6H-2, 131–150 cm 29.92 30.11 15.69 425 6 Y

7Y-31 7C-7H-1, 10–71 cm 30.30 30.91 16.28 384 3 Y

7Y-32 7C-7H-1, 71–144 cm 30.91 31.64 16.95 479 3 Y

7Y-34 1 of 2 7C-7H-2, 68–120 cm 32.28 32.77 18.20 477 5 Y

7Y-34 2 of 2 7C-7H-2, 68–120 cm 32.28 32.77 18.20 523 4 Y

7Y-36 7C-8H-1, 23–90 cm 33.33 34.00 19.34 547 6 Y

7Y-37 7C-8H-1, 90–126 cm 34.00 34.36 19.85 495 2 Y

7Y-38 7B-4H-1, 88.5–120 cm 34.36 34.72 20.21 477 3 Y

7Y-39 7C-9H-2, 7–108.5 cm 34.72 35.60 20.83 518 4 Y

7Y-40 7C-9H-2, 108.5–142 cm 35.60 35.89 21.42 816 4 Y

7Y-41 1 of 2 7C-9H-3, 0–93.5 cm 35.92 36.68 21.97 480 5 Y

7Y-41 2 of 2 7C-9H-3, 0–93.5 cm 35.92 36.68 21.97 488 7 Y

7Y-42 7B-6H-1, 50–113 cm 36.68 37.24 22.63 559 4 Y

16 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002—Continued. 

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream 

to upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram per gram; mm, millimeter; cm, centimeter; <, less than]

Sample ID Replicate Core ID

Relative sample location Total mercury

Sieved to

< 0.060 mm Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

Concentration

(ng/g, dry)

SD

(ng/g, dry)

7Y-43 7C-10H-1, 10–98 cm 37.24 38.06 23.32 587 2 Y

7Y-44 7C-10H-1, 98–150 cm 38.06 38.55 23.98 527 8 Y

7Y-45 7C-10H-2, 5–67 cm 38.55 39.17 24.53 569 5 Y

7Y-46 7C-10H-2, 67–137.5 cm 39.17 39.87 25.19 452 2 Y

7Y-47 7B-9H-1, 57–113 cm 39.87 40.41 25.81 473 3 Y

7Y-48 1 of 2 7C-11H-1, 21–70 cm 40.41 40.88 26.32 462 6 Y

7Y-48 2 of 2 7C-11H-1, 21–70 cm 40.41 40.88 26.32 446 6 Y

7Y-49 7C-11H-1, 70–92 cm 40.88 41.10 26.66 388 9 Y

7Y-50 7C-11H-2, 0–44.5 cm 41.10 41.54 26.99 441 7 Y

7Y-51 7C-11H-2, 44.5–104 cm 41.54 42.13 27.51 440 8 Y

7Y-52 7C-11H-2, 104–130 cm 42.13 42.38 27.93 376 4 Y

7Y-53 7B-10H-1, 102–136 cm 42.38 42.74 28.23 501 3 Y

7Y-54 7C-12H-1, 0–47 cm 42.74 43.21 28.65 536 3 Y

7Y-55 7C-12H-1, 47–99.5 cm 43.21 43.74 29.15 667 2 Y

7Y-56 7C-12H-1, 99.5–133 cm 43.74 44.07 29.58 602 3 Y

7Y-57 1 of 2 7C-12H-2, 0–40.5 cm 44.07 44.47 29.94 332 2 Y

7Y-57 2 of 2 7C-12H-2, 0–40.5 cm 44.07 44.47 29.94 336 2 Y

7Y-58 7C-12H-2, 40.5–69 cm 44.47 44.75 30.28 383 4 Y

7Y-59 1 of 2 7C-12H-2, 69–104 cm 44.75 45.10 30.60 259 2 Y

7Y-59 2 of 2 7C-12H-2, 69–104 cm 44.75 45.10 30.60 262 4 Y

7Y-60 7B-11H-2, 4–47 cm 45.10 45.48 30.96 409 6 Y

7Y-60 B 7C-12H-2, 104–123.5 cm 45.10 45.29 30.87 338 2 Y

7Y-60 C 7C-12H-2, 123.5–150 cm 45.29 45.55 31.09 471 4 Y

7Y-61 7B-11H-2, 47–82 cm 45.48 45.78 31.30 424 6 Y

7Y-62 7B-11H-2, 82–113 cm 45.78 46.06 31.59 374 7 Y

7Y-63 7B-11H-2, 113–140.5 cm 46.06 46.30 31.85 297 3 Y

7Y-64 7C-13H-3, 23–55 cm 46.30 46.52 32.08 294 2 Y

7Y-66 1 of 2 7C-13H-3, 61.5–99 cm 46.57 46.83 32.37 188 1 Y

7Y-66 2 of 2 7C-13H-3, 61.5–99 cm 46.57 46.83 32.37 194 2 Y

7Y-67 7C-13H-3, 99–125.5 cm 46.83 47.02 32.60 280 3 Y

7Y-68 7C-13H-3, 125.5–142 cm 47.02 47.13 32.75 1,365 37 Y

9Y-1 9A-1H-1, 1–127 cm 10.56 11.75 0.60 274 1 Y

9Y-2 1 of 2 9A-1H-2, 25.5–119 cm 11.75 12.57 1.60 292 4 Y

9Y-2 2 of 2 9A-1H-2, 25.5–119 cm 11.75 12.57 1.60 284 2 Y

9Y-3 9A-1H-2, 119–134 cm 12.57 12.70 2.08 317 2 Y

Quality Assurance and Quality Control 17
Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002—Continued. 

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream 

to upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram per gram; mm, millimeter; cm, centimeter; <, less than]

Sample ID Replicate Core ID

Relative sample location Total mercury

Sieved to

< 0.060 mm Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

Concentration

(ng/g, dry)

SD

(ng/g, dry)

9Y-4 9A-2H-1, 0–24 cm 13.23 13.43 2.77 218 2 Y

9Y-5 9A-2H-1, 24–89 cm 13.43 13.96 3.14 290 3 Y

9Y-6 9C-2H-1, 74–114 cm 13.96 14.35 3.60 173 0 Y

9Y-7 1 of 2 9C-2H-2, 0–82 cm 14.35 15.15 4.19 211 1 Y

9Y-7 2 of 2 9C-2H-2, 0–82 cm 14.35 15.15 4.19 241 0 Y

9Y-8 1 of 2 9A-2H-3, 56–108.5 cm 15.15 15.70 4.87 283 1 Y

9Y-8 2 of 2 9A-2H-3, 56–108.5 cm 15.15 15.70 4.87 258 3 Y

9Y-9 9A-2H-3, 108.5–150 cm 15.70 16.14 5.36 139 2 Y

9Y-10 9C-3H-1, 18–91 cm 16.14 16.87 5.95 150 0 Y

9Y-11 9A-3H-1, 95–114 cm 16.87 17.07 6.41 140 2 Y

9Y-12 9A-3H-2, 0–44.5 cm 17.07 17.55 6.75 129 0 Y

9Y-13 1 of 2 9A-3H-2, 44.5–82 cm 17.55 17.95 7.19 145 1 Y

9Y-13 2 of 2 9A-3H-2, 44.5–82 cm 17.55 17.95 7.19 106 0 Y

9Y-14 9A-3H-2, 82–150 cm 17.95 18.69 7.76 222 5 Y

9Y-15 9C-4H-1, 0–97 cm 18.69 19.64 8.61 142 1 Y

9Y-16 9C-4H-2, 9–48 cm 19.64 20.03 9.28 227 2 Y

9Y-17 1 of 2 9C-4H-2, 48–131.5 cm 20.03 20.86 9.89 225 7 Y

9Y-17 2 of 2 9C-4H-2, 48–131.5 cm 20.03 20.86 9.89 263 2 Y

9Y-18 9A-5H-1, 24–118 cm 20.86 21.67 10.71 115 2 Y

9Y-19 9A-5H-2, 3–116 cm 21.67 22.80 11.68 309 2 Y

9Y-20 9C-6H-1, 36–98 cm 23.14 23.76 12.89 183 2 Y

9Y-21 9C-6H-2, 0–95 cm 23.76 24.63 13.64 219 5 Y

9Y-22 9C-6H-2, 95–150 cm 24.63 25.14 14.33 386 2 Y

9Y-23 9A-8H-2, 31–129 cm 25.14 25.99 15.01 466 5 Y

9Y-24 9C-7H-1, 21–89 cm 25.99 26.66 15.77 422 3 Y

9Y-25 9C-7H-1, 89–148 cm 26.66 27.25 16.40 430 4 Y

9Y-26 9C-7H-2, 0–60.5 cm 27.25 27.85 16.99 377 2 Y

9Y-27 1 of 2 9C-7H-2, 60.5–140 cm 27.85 28.64 17.69 444 2 Y

9Y-27 2 of 2 9C-7H-2, 60.5–140 cm 27.85 28.64 17.69 348 2 Y

9Y-28 1 of 2 9C-8H-1, 0–84 cm 28.74 29.52 18.57 376 2 Y

9Y-28 2 of 2 9C-8H-1, 0–84 cm 28.74 29.52 18.57 491 7 Y

9Y-29 9C-8H-1, 84–150 cm 29.52 30.14 19.27 227 1 Y

9Y-30 9C-8H-4, 0–38 cm 30.16 30.53 19.79 577 8 Y

9Y-31 9C-8H-4, 38–82.5 cm 30.53 30.97 20.19 342 3 Y

9Y-32 9C-8H-4, 82.5–125.5 cm 30.97 31.40 20.63 501 0 Y

18 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002—Continued. 

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream 

to upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram per gram; mm, millimeter; cm, centimeter; <, less than]

Sample ID Replicate Core ID

Relative sample location Total mercury

Sieved to

< 0.060 mm Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

Concentration

(ng/g, dry)

SD

(ng/g, dry)

9Y-33 9A-10H-3, 0–35 cm 31.40 31.71 21.00 186 5 Y

9Y-34 9A-10H-3, 35–94.5 cm 31.71 32.26 21.43 232 2 Y

9Y-35 1 of 2 9A-10H-3, 94.5–135.5 cm 32.26 32.63 21.89 192 1 Y

9Y-35 2 of 2 9A-10H-3, 94.5–135.5 cm 32.26 32.63 21.89 184 3 Y

9Y-36 9C-9H-3, 7–41 cm 32.63 32.95 22.23 346 2 Y

9Y-37 1 of 2 9C-9H-3, 41–99 cm 32.95 33.50 22.67 151 3 Y

9Y-37 2 of 2 9C-9H-3, 41–99 cm 32.95 33.50 22.67 153 1 Y

9Y-38 9C-9H-3, 99–130 cm 33.50 33.79 23.09 152 2 Y

9Y-39 9A-11H-2, 55–102 cm 33.79 34.26 23.47 567 9 Y

8Y-1 8A-1H-1, 0–4 cm 10.16 10.20 0.02 211 4 Y

8Y-2 8A-1H-2, 0–17 cm 10.20 10.37 0.13 208 6.3 Y

8Y-3 8A-1H-2, 17–45.5 cm 10.37 10.66 0.36 298 4 Y

8Y-4 8A-1H-2, 45.5–89 cm 10.66 11.09 0.72 127 2 Y

8Y-5 8A-1H-3, 0–127.5 cm 11.09 12.37 1.57 223 5 Y

8Y-6 1 of 2 8A-1H-3, 127.5–150 cm 12.37 12.59 2.32 247 3 Y

8Y-6 2 of 2 8A-1H-3, 127.5–150 cm 12.37 12.59 2.32 263 3 Y

8Y-7 8A-1H-6, 0–5 cm 12.59 12.64 2.46 269 2 Y

8Y-43X 8B-1H-2, 43–101 cm 12.64 13.02 2.67 160 5.8 Y

8Y-8 8A-2H-1, 72–114 cm 13.02 13.44 3.07 165 1 Y

8Y-9 8A-2H-2, 4–22 cm 13.44 13.62 3.37 121 3.0 Y

8Y-10 8A-2H-2, 22–66 cm 13.62 14.06 3.68 235 1.3 Y

8Y-11 8A-2H-2, 66–129 cm 14.06 14.69 4.22 208 4 Y

8Y-12 8B-2H-1, 48–62 cm 14.69 14.83 4.60 16 43 Y

8Y-13 8B-2H-1, 62–127 cm 14.83 15.47 4.99 266 8 Y

8Y-14 8B-2H-2, 5–133 cm 15.47 16.75 5.95 220 4 Y

8Y-15 8A-4H-2, 3–82 cm 16.81 17.60 7.05 152 2 Y

8Y-16 8B-3H-1, 16–83 cm 17.60 18.27 7.78 236 2 Y

8Y-17 1 of 2 8B-3H-2, 0–136 cm 18.27 19.63 8.79 232 0 Y

8Y-17 2 of 2 8B-3H-2, 0–136 cm 18.27 19.63 8.79 221 4 Y

8Y-18 8C-2H-1, 17–81 cm 19.63 20.23 9.77 641 9 Y

8Y-19 8C-2H-1, 81–133 cm 20.23 20.72 10.32 1,020 17 Y

8Y-20 8C-2H-2, 0–31 cm 20.72 20.99 10.70 508 2 Y

8Y-21 8C-2H-2, 31–102 cm 20.99 21.59 11.13 381 9 Y

8Y-22 8A-8H-1, 29–129 cm 21.59 22.59 11.93 284 8 Y

8Y-23 8C-3H-1, 33–66 cm 22.59 22.74 12.51 183 10 Y

Quality Assurance and Quality Control 19
Table 2. Mercury data from the Y series of subsamples from deep cores, Englebright Lake, California, May–June 2002—Continued. 

[Analyses by U.S. Geological Survey laboratory in Boulder, Colo. First digit of sample ID and core ID represents coring site, listed in order from downstream 

to upstream (figure 2). mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; SD, standard deviation; Y, yes; N, no. ng/g, nanogram per gram; mm, millimeter; cm, centimeter; <, less than]

Sample ID Replicate Core ID

Relative sample location Total mercury

Sieved to

< 0.060 mm Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

Concentration

(ng/g, dry)

SD

(ng/g, dry)

8Y-24 8C-3H-1, 66–102 cm 22.74 22.91 12.67 243 2 Y

8Y-25 8C-3H-2, 0–73 cm 22.91 23.27 12.93 282 1 Y

8Y-26 8C-3H-2, 73–135 cm 23.27 23.57 13.26 320 2 Y

8Y-27 8A-10H-1, 42.5–76.5 cm 23.57 23.91 13.58 293 11 Y

8Y-28 8A-10H-1, 76.5–110 cm 23.91 24.24 13.92 280 3 Y

8Y-29 8C-4H-1, 22–141 cm 24.24 25.57 14.75 248 0 Y

8Y-30 8C-4H-2, 0–26 cm 25.57 25.84 15.55 180 8 Y

8Y-31 1 of 2 8C-4H-2, 26–151 cm 25.84 27.15 16.34 290 8 Y

8Y-31 2 of 2 8C-4H-2, 26–151 cm 25.84 27.15 16.34 302 2 Y

8Y-32 8A-12H-1, 113.5–142 cm 27.15 27.43 17.13 223 4 Y

8Y-33 8C-5H-1, 34.5–136 cm 27.43 28.18 17.65 262 6 Y

8Y-34 1 of 2 8C-5H-2, 0–59.5 cm 28.18 28.63 18.25 207 8 Y

8Y-34 2 of 2 8C-5H-2, 0–59.5 cm 28.18 28.63 18.25 193 6 Y

8Y-35 8C-5H-2, 0–59.5 cm 28.63 29.07 18.69 213 3 Y

8Y-36 8A-13H-1, 25–144 cm 29.07 30.26 19.51 214 2 Y

8Y-37 8A, 13H-2, 0–50.5 cm 30.26 30.76 20.35 120 5 Y

8Y-38 8A-13H-2, 50.5–126 cm 30.76 31.50 20.97 258 2 Y

8Y-39 8C-6H-3, 65.5–125 cm 31.50 32.02 21.60 115 4 Y

8Y-40 8A-14H-1, 16–81 cm 32.02 32.67 22.19 147 5 Y

8Y-41 8A-14H-2, 0–21.5 cm 32.67 32.89 22.62 1,568 47 Y

8Y-42 8A-14H-2, 21.5–115 cm 32.89 33.82 23.20 1,239 3.9 Y

Other quality-assurance procedures used by the BMSL in 

conjunction with its MeHg determinations included analyses 

of blanks and spike additions. Three analytical blanks were 

analyzed with each analytical batch of samples. MeHg was 

detected in 13 of the 57 blanks at concentrations less than 

0.028 ng/g (four times the MDL of 0.007 ng/g, dry basis); the 

median blank value was less than the MDL, so the reported 

data were not blank-corrected. Recalculating the results after 

blank correction would result in an average change of less 

than 2 percent. Four of the 166 subsamples in the MEM series 

had MeHg results less than the MDL, and about 10 percent of 

all MeHg analyses (including the MEM series and the shallow 

box cores) had reported values less than five times the MDL. 

Thirty-four pairs of MeHg matrix spikes and matrix spike 

replicates were analyzed with the samples. Recoveries ranged 

from 70 to 130 percent, within the laboratory’s data-quality 

objectives (65 to 135 percent recovery). The RPD between the 

matrix spikes and the matrix spike replicates ranged from 1 to 

35 percent for MeHg, within the BMSL’s data-quality 

objectives.

Deep cores were refrigerated at approximately 4°C 

between collection and splitting; the MEM subsamples used 

for analysis of MeHg were frozen immediately after splitting. 

Shallow cores were processed immediately after collection and 

subsamples for analysis of MeHg were immediately frozen. 

Elapsed time between coring and analysis of MeHg by the 

BMSL ranged from 9 to 10 months for shallow cores and 14 to 

16 months for deep cores. Despite careful handling, it is possible that MeHg concentration changed during sample storage, 

particularly when the deep cores were stored at 4°C rather than 

frozen, because of microbiological activity. However, it is not 

known whether MeHg may have increased or decreased during 

chilled or frozen storage, because changes in either direction 

have been observed in samples from other studies (Eric von 

20 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
der Geest, Moss Landing Marine Laboratories, California, oral 

commun., 2005).

As an additional check on the quality of MeHg analyses, 15 subsamples from the MEM series (deep cores) were 

split evenly and analyzed by both the BMSL and the USGSWDML (table A5). Three of the 15 subsamples had MeHg 

concentrations below the detection limit of the WDML, which 

ranged from 0.094 to 0.13 ng/g. The BMSL had a lower 

detection limit (0.007 ng/g), and it reported MeHg concentrations for these three subsamples that were consistent with the 

WDML results. No values of RPD were computed for these 

three subsamples. The median of the RPD values for MeHg 

analyses in the 12 other split subsamples was 27.7 percent. 

All 12 of the concentration values reported by the BMSL were 

higher than the corresponding values reported by the WDML, 

indicating a consistent bias. The ratio of the MeHg concentrations reported by the two laboratories (WDML:BSML) ranged 

from 60 to 92 percent (table A5); the mean and the median 

values for RPD for the 12 subsamples were 76 percent. A linear least-squares regression for these 12 data points indicates 

a slope of 0.79 and an R2 value of 0.994. A plot of the splitsample data 

(fig. A2) shows the line of perfect agreement (labeled 100 

percent) and a line corresponding to a ratio of 79 percent that 

represents a reasonable fit to the data. 

The WDML analyzed SRMs IAEA-356 and IAEA-405 

also for MeHg; overall results were similar to those produced 

by the BMSL (table A3). The average recoveries for the SRMs 

by the WDML were 92 percent (IAEA-356) and 72 percent 

(IAEA-405), averaging 82 percent; the average SRM recoveries by the BMSL were 74 percent (IAEA-356) and 84 percent 

(IAEA-405), averaging 79 percent. These results suggest that 

laboratory accuracy was not the primary cause of the differences between results for the 15 split subsamples by the two 

laboratories. 

Differences in handling and frozen storage time of the 

split subsamples analyzed by the two laboratories are possible factors in the differences between the results. The split 

subsamples were analyzed for MeHg by the BMSL during 

July–September 2003 and by the WDML during March–April 

2005, about 18–21 months later. Another difference in handling samples was that the split subsamples analyzed by the 

WDML were thawed for a short period (1–2 hours) in August 

2004 and then refrozen, whereas the split subsamples analyzed 

by the BMSL were frozen continuously. Thus it is possible 

that some MeHg degraded during the extended frozen storage time or the brief additional thawed period, resulting in the 

lower concentrations measured by the WDML. 

Because each laboratory analyzed MeHg in sediment during a relatively narrow time frame, the overall findings of this 

study relating to the spatial variability of MeHg concentration 

are not affected by the results of the interlaboratory splitsample comparison or possible sample storage effects. Even 

if MeHg in the subsamples degraded partially during frozen 

storage, the extent of degradation would have been similar for 

all subsamples analyzed by each laboratory. Thus, the 

overall findings of this study relating to the spatial variability 

of MeHg concentration and of the ratio of MeHg to HgT would 

not be affected. 

Trace and Major Elements

The SRM used for trace and major elements by the USGS 

laboratory in Boulder, Colorado, was Buffalo River Sediment 

(NIST 2704; National Institute of Standards and Technology, 

1990). Results of 22 analyses of NIST 2704 (table B1) using 

digestion and analysis procedures identical to those used for 

the environmental samples indicate a wide range of behavior 

for different groups of elements. For several trace elements, 

the SRM results are very close to the certified value (recovery values computed by dividing the overall average values 

by the certified value, in percent): antimony (101), arsenic 

(91), cadmium (99), chromium (92), copper (98), lead (100), 

nickel (95), and zinc (95). For several major elements, the 

SRM results were consistently lower than the certified values: 

aluminum (59), barium (74), calcium (73), magnesium (46), 

and potassium (80). This indicates that the acid digestion procedure used for this study did not result in complete recoveries of these major elements, but did result in more complete 

recoveries of most trace elements, including transition metals 

and the semi-metals antimony and arsenic.

Digestion blanks were analyzed as part of each batch 

of environmental samples, a total of 16 (table B2). Concentrations measured in these blanks were generally near the 

detection limit for most trace metals, much lower than the 

values for environmental samples, so the data did not need 

to be blank-corrected. Blank spikes were prepared for seven 

selected elements (arsenic, cadmium, calcium, copper, lead, 

magnesium, and zinc) on six occasions (table B3). Recoveries from blank spikes were within an acceptable range (85 to 

115 percent of expected concentration) for all analyses except 

one of the analyses for arsenic.

Replicate digestions were made of 29 subsamples, which 

were analyzed for 53 trace and major elements (table B4). 

For several trace elements of interest, median values of RPD 

were less than or equal to 5 percent, indicating a high degree 

of reproducibility; median RPD values (in percent) include 

arsenic (3), antimony (4), copper (5), lead (1.5), nickel (3), 

and zinc (4). For major elements, median RPD values for 

replicate subsamples were typically in the range of 9 to 

15 percent: aluminum (15), barium (12), calcium (9), magnesium (15), potassium (9), and sodium (6). The digestate from 

each replicate subsample was analyzed in triplicate. Standard 

deviations reported in tables B4 (replicate subsamples) and B5

(all subsamples) indicate analytical variability (precision). For 

concentrations greater than 10 times the MDL, standard deviation values for trace metals were generally less than 20 percent 

of the average amount present. For concentrations closer to 

the MDL, standard deviation values tend to represent a higher 

proportion of the amount present (Alpers and others, 2000).

Quality Assurance and Quality Control 21
Results

Total Mercury and Methylmercury

Concentration data for total mercury (HgT) and methylmercury (MeHg) in subsamples from shallow and deep cores 

are presented in this section. Data for grain-size distribution 

and loss on ignition for these subsamples were reported by 

Snyder and others (2004b). The Y-series subsamples were 

analyzed for trace and major elements, as discussed in a later 

section. Data for HgT are given in tables 2 and 3 (Y-series and 

MEM-series) for the deep cores and in table 4 for the shallow cores. Data for MeHg are given in table 3 (MEM-series) 

and table 4 (shallow cores). The distribution of compositions 

with depth for HgT and selected trace elements in Y-series 

subsamples is shown on figures 4–8. Data for HgT, MeHg, 

and the ratio of MeHg to HgT for the MEM-series are plotted 

with respect to depth in figure 9. Some statistics regarding 

the spatial variation (longitudinal and vertical) of HgT, MeHg, 

and the ratio of HgT to MeHg are summarized in tables 5 and 

6. Summary statistics regarding the longitudinal variation of 

selected trace elements are given in table 7. A quantitative statistical analysis of the relations between grain-size distribution 

and concentrations of HgT, MeHg, loss on ignition, and other 

sediment properties, and trends of Hg concentration with time 

in the context of the sedimentation history of the reservoir will 

be published separately. 

The Y-series of subsamples from the deep cores best 

represent the spatial distribution of HgT in Englebright Lake 

sediments. The Y-series represents a continuous vertical 

profile of the sediment deposit at several locations, taking 

advantage of multiple adjacent drill holes to avoid gaps in 

the profile between core sections. A total of 202 Y-series 

subsamples from five deep coring locations were analyzed 

for total mercury (table 2); in upstream order, starting near 

Englebright Dam, the sites are 1, 4, 7, 9, and 8 (fig. 2). Plots of 

HgT versus depth for the Y-series subsamples are shown in box 

A of figures 4–8. Note that the Y-series subsamples from site 

4 were not screened prior to analysis, whereas the subsamples 

from the other four sites were screened at 0.060 mm and only 

the fines fraction (silt- and clay-size particles) was analyzed. 

In general, the fine-grained fraction of sediment tends to have 

higher concentrations of trace metals, including mercury 

and methylmercury, because of the association of the trace 

metals with fine-grained particles containing hydrous ferric 

oxides, clay minerals, and organic material (Horowitz, 1991; 

Hunerlach and others, 2004). Lines on the plots in figures 4–8

represent vertical trends of concentration values; the lines 

pass through the average of the depth interval values for the 

replicate subsamples.

The MEM-series of subsamples, also from the deep 

cores, provided a linkage between analyses of HgT and MeHg. 

These subsamples are discrete subsamples of a more limited 

vertical extent (typically about 10–15 cm) compared with 

the continuous, Y-series subsamples (typically 25 to 100 cm; 

Snyder and others, 2004a). The MEM-series subsamples were 

analyzed for HgT and MeHg by the BMSL (table 3). The 

MEM-series subsamples were also analyzed for grain-size 

distribution (fig. 9) and loss on ignition (Snyder and others, 

2004b), but were not analyzed for trace or major elements. 

All seven of the deep coring sites were sampled in the MEMseries; in upstream order, these sites are 1, 6, 4, 7, 9, 8, and 2 

(fig. 2). Plots of HgT and MeHg versus depth for the MEMseries subsamples are shown in figures 9A and 9B. A plot of 

the ratio MeHg/HgT versus depth is shown in figure 9C, and 

the relation between median grain size and depth is shown in 

figure 9D. 

At the deep coring sites closest to Englebright Dam (sites 

1, 6, and 4), concentrations of HgT in subsamples from both 

the Y-series (sites 1 and 4; figs. 4A, 5A) and the MEM-series 

(sites 1, 6, and 4; fig. 9A) were generally 100 to 500 ng/g 

(nanograms per gram). The median grain size at these sites 

(figs. 4H, 5H) was consistently silt-sized (0.004 to 0.063 mm) 

(figs. 4H, 5H, 9D). At the more upstream deep coring sites (7, 

9, 8, and 2), unsieved MEM-series subsamples from the upper 

parts of the profile have lower concentrations of HgT, generally from 2 to 100 ng/g, and typically coarser grain size, with 

median grain size in the sand range (0.063 to 2.0 mm; fig. 9D). 

In contrast, the MEM-series subsamples from the lower parts 

of these profiles have median grain size in the fine sand and 

silt range (about 0.007 to 0.3 mm; fig. 9D) and higher 

concentrations of HgT (fig. 9A). 

The fines fraction from the upper parts of the upstream 

coring site profiles (Y-series subsamples, sites 7, 9, and 8) had 

concentrations of HgT in most subsamples ranging from about 

100 to 300 ng/g (figs. 6A, 7A, and 8A). In the fines fraction 

from the sieved Y-series subsamples at sites 7 and 9 (figs. 6A

and 7A) concentrations of HgT in the lower parts of the profile 

were generally higher (most subsamples 200 to 600 ng/g) than 

those in the upper parts of the same profiles. At site 8 (fig. 8A), 

the HgT concentration of the fines fraction ranged from 100 to 

300 ng/g for most subsamples; four intervals in the middle of 

the profile had concentrations from about 300 to 1,000 ng/g. 

The highest concentrations of HgT in the fines fraction 

of sieved subsamples (Y-series) were found in the bottom 

interval at site 7 (fig. 6A) and the bottom two intervals at site 

8 (fig. 8A). In these three subsamples, concentrations of HgT

ranged from about 1,200 to 1,600 ng/g. Other trace elements, 

including arsenic, lead, and antimony, were also elevated in 

these subsamples, as discussed below.

22 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 3. Mercury and methylmercury data from the MEM series of subsamples from deep cores, Englebright Lake, California, 

May–June 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; 

HgT, total mercury; MeHg, methylmercury; ng/g, nanogram per gram; %, percentage; —, not determined; <, less than]

Sample

 ID

(GS-)

Replicate Core ID

Relative sample location Total 

mercury

concentration

(ng/g, dry)

Methymercury

concentration

(ng/g, dry)

Percent 

dry

weight

Ratio of

MeHg to HgT

(%)

Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

1 1C-1E-1 / MEM, 23–34 cm 62.09 62.20 1.36 355 1.5 57.0 0.42

2 1C-1E-2 / MEM, 56–66 cm 62.83 62.93 2.09 176 0.098 62.6 0.056

3 1C-2E-2 / MEM, 15–25 cm 65.27 65.37 4.53 575 0.77 63.8 0.13

4 4C-1H-1 / MEM, 20–30 cm 34.40 34.50 0.08 175 0.64 64.5 0.37

5 2B-1H-1 / MEM, 114–124 cm 4.96 5.06 1.19 12.6 0.051 80.1 0.40

6 2B-1H-1 / MEM, 53–63 cm 4.35 4.45 0.58 21.2 0.065 78.3 0.31

7 4C-1H-2 / MEM, 72–82 cm 35.64 35.74 1.32 26.6 1.4 47.8 5.1

8 4C-2H-1 / MEM, 72–82 cm 37.29 37.39 2.97 364 0.66 59.3 0.18

9 4C-2H-2 / MEM, 64–74 cm 38.65 38.75 4.33 264 0.67 57.4 0.25

10 4C-3H-1 / MEM, 70–80 cm 40.15 40.25 5.83 215 0.50 62.1 0.23

11 4C-3H-2 / MEM, 71–81 cm 41.39 41.48 7.06 223 3.0 60.3 1.3

12 1 of 2 4C-4H-2 / MEM, 63–73 cm 43.25 43.34 8.92 266 1.2 63.6 0.45

12 2 of 2 4C-4H-2 / MEM, 63–73 cm 43.25 43.34 8.92 231 — 63.6 —

13 4C-4H-3 / MEM, 67–77 cm 44.60 44.70 10.28 359 0.36 66.9 0.10

14 4C-5H-2 / MEM, 44–54 cm 46.07 46.16 11.74 363 1.0 63.5 0.28

15 4C-5H-3 / MEM, 52–62 cm 47.08 47.18 12.76 309 0.69 67.7 0.22

16 4C-5H-4 / MEM, 45–55 cm 47.97 48.07 13.65 1,150 3.3 64.1 0.29

17 4C-6E-1 / MEM, 58–68 cm 49.24 49.34 14.92 125 0.060 61.9 0.048

18 4D-1H-1 / MEM, 41–51 cm 34.75 34.85 0.43 115 1.4 59.7 1.2

19 4D-1H-2 / MEM, 60–70 cm 35.82 35.92 1.50 183 1.5 56.2 0.82

20 4D-2E-1 / MEM, 51–61 cm 37.88 37.98 3.56 182 0.58 66.4 0.32

21 4D-3E-1 / MEM, 51–61 cm 40.46 40.54 6.13 241 0.91 58.0 0.38

22 4D-3E-2 / MEM, 49–59 cm 41.28 41.35 6.94 256 0.92 57.2 0.36

23 4D-3E-3 / MEM, 50–60 cm 42.14 42.21 7.81 231 0.79 57.4 0.34

24 4D-4E-1 / MEM, 112–122 cm 43.68 43.76 9.35 232 1.0 63.0 0.44

25 4D-5E-1 / MEM, 32–42 cm 45.70 45.80 11.38 286 1.2 64.8 0.42

26 4D-5E-2 / MEM, 55–65 cm 46.50 46.60 12.18 386 0.89 62.8 0.23

27 4D-6H-1 / MEM, 68–78 cm 49.11 49.21 14.79 251 0.20 67.4 0.081

28 1 of 3 6A-1H-2 / MEM, 70–80 cm 52.69 52.79 1.51 386 1.7 49.4 0.45

28 2 of 3 6A-1H-2 / MEM, 70–80 cm 52.69 52.79 1.51 337 1.9 49.4 0.56

28 3 of 3 6A-1H-2 / MEM, 70–80 cm 52.69 52.79 1.51 — 1.9 49.4 —

29 6A-3E-3 / MEM, 53–63 cm 57.65 57.72 6.45 286 0.85 63.8 0.30

30 6A-4E-1 / MEM, 65–75 cm 59.02 59.12 7.84 539 0.43 60.0 0.080

31 6B-1H-1 / MEM, 48–58 cm 52.00 52.09 0.82 355 1.6 54.6 0.44

32 6B-1H-2 / MEM, 81–91 cm 53.67 53.76 2.48 93.8 0.063 64.3 0.067

33 1 of 2 6B-2H-1 / MEM, 61–71 cm 55.15 55.24 3.96 344 0.87 61.5 0.25

33 2 of 2 6B-2H-1 / MEM, 61–71 cm 55.15 55.24 3.96 — 0.93 61.5 —

34 1 of 2 6B-2H-2 / MEM, 109–119 cm 57.02 57.12 5.84 453 0.88 58.1 0.19

Table 3. Mercury and methylmercury data from the MEM series of subsamples from deep cores, Englebright Lake, California, 

May–June 2002.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; 

HgT, total mercury; MeHg, methylmercury; ng/g, nanogram per gram; %, percentage; —, not determined; <, less than]

Results 23
Table 3. Mercury and methylmercury data from the MEM series of subsamples from deep cores, Englebright Lake, California, 

May–June 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; 

HgT, total mercury; MeHg, methylmercury; ng/g, nanogram per gram; %, percentage; —, not determined; <, less than]

Sample

 ID

(GS-)

Replicate Core ID

Relative sample location Total 

mercury

concentration

(ng/g, dry)

Methymercury

concentration

(ng/g, dry)

Percent 

dry

weight

Ratio of

MeHg to HgT

(%)

Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

34 2 of 2 6B-2H-2 / MEM, 109–119 cm 57.02 57.12 5.84 471 — 58.1 —

35 6A-3E-1 / MEM, 62–72 cm 56.79 56.86 5.60 259 0.57 64.3 0.22

36 6D-1H-1 / MEM, 110–120 cm 52.26 52.36 1.08 153 0.35 60.6 0.23

37 6D-1H-2 / MEM, 54–64 cm 53.04 53.14 1.86 152 0.093 59.5 0.061

38 6D-2E-1 / MEM, 41–51 cm 54.57 54.67 3.39 391 0.21 59.4 0.053

39 6E-1H-2 / MEM, 51–62 cm 52.92 53.03 1.74 300 0.76 51.9 0.25

40 6E-2H-2 / MEM, 77–83 cm 55.24 55.30 4.04 422 1.3 57.1 0.30

41 6E-3E-1 / MEM, 26–34 cm 57.26 57.34 6.07 301 0.43 59.6 0.14

42 6E-3E-2 / MEM, 26–31 cm 58.28 58.33 7.08 584 3.6 59.8 0.62

43 7A-1H-1 / MEM, 34–40 cm 14.45 14.51 0.15 39.4 0.12 73.8 0.31

44 7A-1H-1 / MEM, 84–92 cm 14.95 15.03 0.66 402 0.86 59.0 0.21

45 7A-1H-2 / MEM, 58–68 cm 15.91 16.01 1.63 219 1.1 53.5 0.52

46 7A-2H-1 / MEM, 107–114 cm 18.13 18.20 3.83 23.6 0.090 74.5 0.38

47 7A-2H-2 / MEM, 32–40 cm 18.76 18.84 4.47 22.6 0.21 73.9 0.91

48 7A-2H-2 / MEM, 124–132 cm 19.68 19.76 5.39 206 0.47 63.6 0.23

49 7A-3H-1 / MEM, 106–114 cm 21.09 21.17 6.80 138 0.27 62.7 0.19

50 7A-3H-2 / MEM, 91–100 cm 22.25 22.34 7.97 224 0.40 62.1 0.18

51 7A-4H-1 / MEM, 40–47 cm 23.44 23.51 9.15 14.7 0.053 80.2 0.36

52 7A-4H-2 / MEM, 92–100 cm 25.14 25.22 10.85 140 1.5 33.6 1.1

53 7B-1H-1 / MEM, 68–79 cm 24.70 24.81 10.43 361 3.0 51.3 0.84

54 7B-1H-2 / MEM, 46–56 cm 25.83 25.93 11.55 51.9 0.026 76.3 0.051

55 7B-2H-1 / MEM, 82–90 cm 28.03 28.11 13.74 58.4 0.023 73.8 0.039

56 7B-2H-2 / MEM, 104–112 cm 29.40 29.48 15.11 37.5 0.13 75.9 0.35

57 7B-3H-1 / MEM, 18–28 cm 30.08 30.18 15.80 132 6.8 43.1 5.2

58 7B-3H-1 / MEM, 74–82 cm 30.64 30.72 16.35 39.8 0.15 75.3 0.37

59 7B-3H-2 / MEM, 24–34 cm 31.38 31.48 17.10 94.5 0.49 74.9 0.52

60 7B-4H-1 / MEM, 54–65 cm 33.00 33.11 18.73 76.3 1.3 69.2 1.7

61 7B-5H-1 / MEM, 57–71 cm 33.86 33.98 19.59 100 1.1 68.5 1.1

62 1 of 2 7B-5H-1 / MEM, 95–107 cm 34.17 34.27 19.89 233 0.77 67.7 0.33

62 2 of 2 7B-5H-1 / MEM, 95–107 cm 34.17 34.27 19.89 247 — 67.7 —

63 7B-6H-1 / MEM, 37–49 cm 34.57 34.68 20.29 298 2.0 64.8 0.65

64 7B-7H-1 / MEM, 95–113 cm 36.30 36.48 22.06 259 0.98 67.1 0.38

65 7B-8H-1 / MEM, 103–114 cm 37.86 37.97 23.59 154 0.20 71.9 0.13

66 7B-9H-1 / MEM, 72–82 cm 39.09 39.19 24.81 635 0.50 65.3 0.079

67 7B-10H-1 / MEM, 61–72 cm 40.48 40.59 26.21 997 0.18 67.7 0.018

68 7B-11H-1 / MEM, 3–15 cm 41.45 41.56 27.18 123 0.53 73.6 0.43

69 7B-11H-2 / MEM, 54–64 cm 43.37 43.47 29.09 239 0.98 67.9 0.41

70 7B-12H-1 / MEM, 7–19 cm 44.48 44.60 30.21 87.7 0.23 65.9 0.26

24 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 3. Mercury and methylmercury data from the MEM series of subsamples from deep cores, Englebright Lake, California, 

May–June 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; 

HgT, total mercury; MeHg, methylmercury; ng/g, nanogram per gram; %, percentage; —, not determined; <, less than]

Sample

 ID

(GS-)

Replicate Core ID

Relative sample location Total 

mercury

concentration

(ng/g, dry)

Methymercury

concentration

(ng/g, dry)

Percent 

dry

weight

Ratio of

MeHg to HgT

(%)

Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

71 1 of 2 7B-12H-2 / MEM, 29–39 cm 44.93 44.98 30.63 113 0.044 62.0 0.038

71 2 of 2 7B-12H-2 / MEM, 29–39 cm 44.93 44.98 30.63 — 0.041 62.0 —

72 7B-12H-3 / MEM, 34–44 cm 45.08 45.09 30.76 165 0.058 73.6 0.035

73 7C-1H-1 / MEM, 16–25 cm 14.49 14.58 0.21 46.3 0.27 71.2 0.58

74 1 of 2 7C-1H-2 / MEM, 64–74 cm 16.14 16.24 1.86 133 0.95 62.3 0.72

74 2 of 2 7C-1H-2 / MEM, 64–74 cm 16.14 16.24 1.86 — 1.1 62.3 —

75 7C-2H-1 / MEM, 86–95 cm 17.57 17.66 3.29 33.6 0.22 76.1 0.66

76 7C-2H-2 / MEM, 54–64 cm 18.75 18.85 4.47 33.7 0.069 74.7 0.21

77 7C-3H-1 / MEM, 72–80 cm 20.36 20.44 6.07 236 0.90 63.7 0.38

78 7C-3H-2 / MEM, 70–79 cm 21.78 21.86 7.49 630 1.1 62.5 0.18

79 7C-4H-1 / MEM, 34–44 cm 23.00 23.10 8.72 257 0.78 59.3 0.30

80 7C-4H-2 / MEM, 35–44 cm 23.49 23.58 9.21 27.5 <0.007 78.5 <0.03

81 7C-4H-3 / MEM, 124–131 cm 25.17 25.24 10.88 63.6 0.23 72.3 0.36

82 7C-5H-1 / MEM, 17–29 cm 25.72 25.84 11.45 136 2.2 46.7 1.6

83 7C-6H-1 / MEM, 25–37 cm 27.52 27.62 13.24 191 2.6 34.6 1.4

84 7C-6H-2 / MEM, 73–81 cm 29.34 29.42 15.05 44.0 0.10 76.3 0.23

85 7C-7H-1 / MEM, 90–99 cm 31.10 31.19 16.81 85.1 0.072 74.0 0.085

86 7C-7H-2 / MEM, 92–102 cm 32.50 32.60 18.22 333 1.5 65.5 0.45

87 7C-9H-2 / MEM, 85–93 cm 35.40 35.47 21.10 58.2 0.048 76.6 0.082

88 7C-8H-1 / MEM, 74–81 cm 33.84 33.91 19.55 45.8 0.31 75.6 0.68

89 7C-9H-3 / MEM, 75–84 cm 36.53 36.61 22.24 183 1.5 69.8 0.80

90 7C-10H-1 / MEM, 60–70 cm 37.71 37.80 23.43 110 0.71 69.1 0.65

91 7C-10H-2 / MEM, 73–82 cm 39.23 39.32 24.95 251 0.83 66.7 0.33

92 7C-11H-1 / MEM, 43–52 cm 40.62 40.71 26.33 308 0.34 68.3 0.11

93 7C-11H-2 / MEM, 49–57 cm 41.58 41.66 27.29 460 1.1 69.8 0.25

94 7C-12H-1 / MEM, 58–68 cm 43.32 43.42 29.04 167 1.5 67.9 0.89

95 7C-12H-2 / MEM, 69–79 cm 44.75 44.85 30.47 95.1 0.16 71.2 0.17

96 7C-13H-1 / MEM, 10–20 cm 45.83 45.93 31.55 413 0.20 66.3 0.047

97 1 of 2 7C-13H-3 / MEM, 38–48 cm 46.41 46.48 32.11 237 0.45 68.1 0.19

97 2 of 2 7C-13H-3 / MEM, 38–48 cm 46.41 46.48 32.11 210 — 68.1 —

98 7C-13H-3 / MEM, 126–135 cm 47.02 47.08 32.72 95.7 0.095 78.8 0.10

99 8A-1H-2 / MEM, 64–73 cm 10.64 10.73 0.53 14.2 0.035 80.2 0.24

100 8A-1H-3 / MEM, 89–101 cm 11.78 11.90 1.68 5.7 0.026 77.7 0.46

101 8A-2H-2 / MEM, 47–56 cm 13.87 13.96 3.76 100 0.78 68.6 0.78

102 8A-3H-2 / MEM, 73–84 cm 15.55 15.63 5.43 21.8 0.019 82.4 0.086

103 8A-4H-1 / MEM, 44–51 cm 16.67 16.74 6.55 9.5 0.018 78.9 0.19

104 8A-4H-2 / MEM, 69–77 cm 17.47 17.55 7.35 23.7 0.034 82.3 0.14

105 8A-7H-2 / MEM, 51–63 cm 19.88 20.00 9.78 37.3 0.063 77.7 0.17

Results 25
Table 3. Mercury and methylmercury data from the MEM series of subsamples from deep cores, Englebright Lake, California, 

May–June 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; 

HgT, total mercury; MeHg, methylmercury; ng/g, nanogram per gram; %, percentage; —, not determined; <, less than]

Sample

 ID

(GS-)

Replicate Core ID

Relative sample location Total 

mercury

concentration

(ng/g, dry)

Methymercury

concentration

(ng/g, dry)

Percent 

dry

weight

Ratio of

MeHg to HgT

(%)

Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

106 8A-8H-1 / MEM, 110–118 cm 22.40 22.48 12.28 7.6 0.009 84.1 0.12

107 8A-8H-2 / MEM, 0–13 cm 22.71 22.73 12.56 201 0.20 65.4 0.10

108 8A-10H-1 / MEM, 77–85 cm 23.91 23.99 13.79 34.9 0.057 75.1 0.16

109 8A-11H-1 / MEM, 76–83 cm 25.28 25.35 15.16 142 0.86 61.6 0.61

110 8A-12H-1 / MEM, 38–52 cm 26.41 26.55 16.32 174 0.57 63.7 0.33

111 8A-12H-2 / MEM, 38–47 cm 27.77 27.86 17.65 109 0.42 71.7 0.38

112 1 of 2 8A-13H-1 / MEM, 68–78 cm 29.50 29.60 19.39 95.0 0.14 71.7 0.15

112 2 of 2 8A-13H-1 / MEM, 68–78 cm 29.50 29.60 19.39 — 0.15 71.7 —

113 8A-13H-2 / MEM, 44–55 cm 30.69 30.80 20.59 98.6 0.095 66.3 0.10

114 8A-14H-1 / MEM, 27–37 cm 32.13 32.23 22.02 64.3 0.041 62.7 0.063

115 8A-14H-2 / MEM, 25–33 cm 32.92 33.00 22.80 365 0.24 70.9 0.065

116 8B-1H-1 / MEM, 30–38 cm 11.48 11.56 1.36 18.1 0.016 83.2 0.090

117 8B-1H-2 / MEM, 69–78 cm 12.67 12.76 2.56 23.1 <0.007 79.8 <0.03

118 8B-2H-1 / MEM, 104–112 cm 15.24 15.32 5.12 110 0.15 70.0 0.14

119 8B-2H-2 / MEM, 62–71 cm 16.04 16.13 5.93 16.4 0.019 79.2 0.12

120 8B-3H-1 / MEM, 50–58 cm 17.67 17.75 7.55 18.0 0.022 82.9 0.12

121 8B-3H-2 / MEM, 117–127 cm 19.17 19.27 9.06 15.5 0.097 73.5 0.63

122 8C-2H-1 / MEM, 92–101 cm 20.05 20.14 9.94 81.6 0.32 72.9 0.39

123 1 of 2 8C-2H-2 / MEM, 52–61 cm 20.93 21.01 10.81 302 0.94 64.7 0.31

123 2 of 2 8C-2H-2 / MEM, 52–61 cm 20.93 21.01 10.81 — 1.0 64.7 —

124 1 of 2 8C-3H-1 / MEM, 52–61 cm 22.54 22.62 12.42 416 0.51 64.8 0.12

124 2 of 2 8C-3H-1 / MEM, 52–61 cm 22.54 22.62 12.42 237 — 64.8 —

125 8C-3H-2 / MEM, 63–71 cm 23.64 23.72 13.52 <5 <0.007 81.2 —

126 8C-4H-1 / MEM, 75–83 cm 25.18 25.26 15.06 105 0.20 74.5 0.19

127 8C-4H-2 / MEM, 77–87 cm 26.56 26.65 16.45 102 0.71 70.0 0.69

128 8C-5H-1 / MEM, 56–65 cm 27.87 27.96 17.76 100 0.19 69.0 0.19

129 8C-5H-2 / MEM, 26–36 cm 28.93 29.03 18.82 181 0.33 63.7 0.18

130 1 of 2 8C-6H-1 / MEM, 69–79 cm 30.97 31.06 20.86 130 0.074 65.6 0.057

130 2 of 2 8C-6H-1 / MEM, 69–79 cm 30.97 31.06 20.86 — 0.087 65.6 —

131 8C-6H-3 / MEM, 40–50 cm 32.13 32.22 22.01 133 0.62 69.4 0.46

132 1 of 2 8C-7H-1 / MEM, 18–28 cm 33.41 33.50 23.29 128 0.17 60.7 0.13

132 2 of 2 8C-7H-1 / MEM, 18–28 cm 33.41 33.50 23.29 124 — 60.7 —

133 9A-1H-1 / MEM, 90–103 cm 11.31 11.42 0.80 35.6 0.092 74.8 0.26

134 9A-1H-2 / MEM, 83–94 cm 12.43 12.53 1.92 216 1.7 57.9 0.77

135 9A-2H-1 / MEM, 49–56 cm 13.94 14.01 3.41 119 0.55 66.2 0.46

136 9A-2H-3 / MEM, 110–119 cm 15.74 15.83 5.23 20.1 0.027 77.8 0.14

137 9A-3H-1 / MEM, 72–80 cm 16.65 16.73 6.13 21.3 0.020 78.9 0.10

138 9A-3H-2 / MEM, 39–48 cm 17.46 17.55 6.95 70.7 0.43 65.2 0.61

26 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 3. Mercury and methylmercury data from the MEM series of subsamples from deep cores, Englebright Lake, California, 

May–June 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. mbls, meters below lake surface (spillway elevation); mblf, meters below lake floor; 

HgT, total mercury; MeHg, methylmercury; ng/g, nanogram per gram; %, percentage; —, not determined; <, less than]

Sample

 ID

(GS-)

Replicate Core ID

Relative sample location Total 

mercury

concentration

(ng/g, dry)

Methymercury

concentration

(ng/g, dry)

Percent 

dry

weight

Ratio of

MeHg to HgT

(%)

Top

(mbls)

Bottom

(mbls)

Midpoint

(mblf)

139 9A-4H-2 / MEM, 72–80 cm 19.80 19.87 9.27 5.4 <0.007 86.3 <0.13

140 9A-5H-1 / MEM, 53–61 cm 21.12 21.19 10.59 12.0 0.025 79.7 0.20

141 9A-7H-1 / MEM, 69–78 cm 23.71 23.78 13.18 120 0.012 80.7 0.010

142 9A-8H-2 / MEM, 93–101 cm 25.58 25.66 15.06 44.0 0.37 73.9 0.83

143 9A-9H-1 / MEM, 88–96 cm 26.88 26.96 16.36 245 1.7 68.1 0.68

144 9A-9H-2 / MEM, 74–83 cm 27.94 28.02 17.42 266 0.69 72.2 0.26

145 9A-10H-1 / MEM, 40–49 cm 29.24 29.32 18.72 204 0.87 70.5 0.42

146 9A-10H-3 / MEM, 70–79 cm 30.98 31.07 20.47 206 0.21 69.7 0.10

147 9A-11H-1 / MEM, 107–116 cm 32.28 32.42 21.79 65.5 0.036 63.5 0.054

148 9C-1H-1 / MEM, 62–69 cm 11.29 11.36 0.76 11.6 0.027 77.7 0.23

149 9C-1H-2 / MEM, 105–114 cm 12.56 12.65 2.05 33.2 0.051 74.2 0.15

150 1 of 2 9C-2H-1 / MEM, 16–26 cm 13.40 13.50 2.89 274 2.2 55.4 0.82

150 2 of 2 9C-2H-1 / MEM, 16–26 cm 13.40 13.50 2.89 — 2.3 55.4 —

151 9C-2H-2 / MEM, 17–26 cm 14.51 14.60 4.00 <5 0.016 80.2 —

152 9C-2H-2 / MEM, 98–107 cm 15.31 15.40 4.79 187 0.74 62.8 0.40

153 9C-3H-1 / MEM, 88–98 cm 16.84 16.94 6.33 15.3 0.033 77.8 0.21

154 9C-3H-2 / MEM, 26–36 cm 17.34 17.42 6.82 88.0 0.24 68.4 0.28

155 9C-4H-1 / MEM, 44–54 cm 19.12 19.22 8.61 25.1 0.018 81.0 0.071

156 9C-4H-2 / MEM, 70–79 cm 20.25 20.34 9.73 10.9 0.021 81.4 0.19

157 9C-5H-1 / MEM, 51–61 cm 21.41 21.51 10.90 <5 0.013 85.4 —

158 9C-5H-2 / MEM, 46–57 cm 22.04 22.13 11.52 158 0.99 67.1 0.62

159 9C-6H-1 / MEM, 60–68 cm 23.38 23.46 12.86 34.7 0.014 80.4 0.040

160 9C-6H-2 / MEM, 70–78 cm 24.76 24.83 14.24 12.6 0.22 75.4 1.7

161 1 of 2 9C-7H-1 / MEM, 70–81 cm 26.48 26.59 15.97 172 0.58 69.1 0.33

161 2 of 2 9C-7H-1 / MEM, 70–81 cm 26.48 26.59 15.97 100 — 69.1 —

162 9C-7H-2 / MEM, 65–74 cm 27.89 27.98 17.38 324 0.61 68.2 0.19

163 9C-8H-1 / MEM, 57–67 cm 29.27 29.36 18.76 338 2.3 64.0 0.66

164 9C-8H-4 / MEM, 70–79 cm 30.85 30.94 20.33 337 0.25 65.9 0.074

165 1 of 2 9C-9H-2 / MEM, 33–43 cm 32.09 32.19 21.58 225 0.21 67.0 0.092

165 2 of 2 9C-9H-2 / MEM, 33–43 cm 32.09 32.19 21.58 — 0.21 67.0 —

166 9C-9H-3 / MEM, 10–20 cm 32.66 32.75 22.15 281 0.60 69.7 0.21

Results 27
Table 4. Mercury and methylmercury data for shallow cores taken at Englebright Lake, California, October 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. MeHg, methylmercury; HgT, total mercury. cm, centimeter; ng/g, nanograms per 

gram; —, not determined]

Site ID

Depth below 

lake floor

(cm)

Lab ID Core

replicate

Lab

replicate

Percent 

dry

weight

Total 

mercury

(ng/g dry)

Methylmercury

(ng/g dry)

Ratio of 

MeHg to 

HgT

(percentage)

10F-B 0–1 GS 200 23.4 307 1.1 0.37

10F-B 1–2 GS 201 29.7 251 1.0 0.40

10F-B 2–3 GS 202 32.8 303 0.90 0.30

10F-B 3–4 GS 203 37.3 283 0.86 0.30

10F-B 4–8 GS 204 1 of 2 43.9 256 0.47 0.18

10F-B 4–8 GS 205 2 of 2 43.2 243 0.80 0.33

10F-B 8–12 GS 206 49.7 265 0.71 0.27

10G-B 0–1 GS 207 26.8 224 0.92 0.41

10G-B 1–2 GS 208 30.6 288 1.5 0.51

10G-B 2–3 GS 209 1 of 2 33.2 258 0.73 0.28

10G-B 2–3 GS 209 2 of 2 33.2 — 0.89 —

10G-B 3–4 GS 210 37.6 288 0.60 0.21

10G-B 4–8 GS 211 43.0 265 0.96 0.36

10G-B 8–12 GS 212 1 of 2 47.0 274 1.1 0.40

10G-B 8–12 GS 213 2 of 2 47.3 237 1.0 0.43

11A-B 0–4 GS 214 36.2 252 1.7 0.66

11A-B 4–8 GS 215 1 of 4 44.4 228 0.57 0.25

11A-B 4–8 GS 215 2 of 4 44.4 — 0.87 —

11A-B 4–8 GS 215 3 of 4 44.4 — 0.90 —

11A-B 4–8 GS 215 4 of 4 44.4 — 0.49 —

11A-B 8–12 GS 216 44.4 233 0.43 0.18

11B-B 0–4 GS 217 27.9 230 0.40 0.17

11B-B 4–8 GS 218 1 of 2 37.5 380 0.37 0.10

11B-B 4–8 GS 218 2 of 2 37.5 295 — —

11B-B 8–12 GS 219 41.1 298 0.52 0.18

11C-B1 0–4 GS 220 1 of 1 30.5 329 0.85 0.26

11C-B1 4–8 GS 221 1 of 1 48.1 228 0.41 0.18

11C-B1 8–12 GS 222 1 of 1 48.9 227 0.49 0.21

11C-B2 0–4 GS 223 2 of 2 35.1 285 0.49 0.17

11C-B2 4–8 GS 224 2 of 2 48.4 270 0.25 0.091

11C-B2 8–12 GS 225 2 of 2 48.7 268 0.58 0.21

11D-B 0–4 GS 226 40.5 271 0.56 0.21

11D-B 4–8 GS 227 50.4 222 0.33 0.15

11D-B 8–11 GS 228 46.9 222 0.55 0.25

11E-B 0–4 GS 229 40.3 245 4.0 1.6

11E-B 4–7 GS 230 41.7 212 3.8 1.8

11F-B 0–1 GS 231 29.1 308 1.1 0.35

11F-B 1–2 GS 232 39.5 333 0.69 0.21

Table 4. Mercury and methylmercury data for shallow cores taken at Englebright Lake, California, October 2002.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. MeHg, methylmercury; HgT, total mercury. cm, centimeter; ng/g, nanograms 

per gram; —, not determined]

28 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 4. Mercury and methylmercury data for shallow cores taken at Englebright Lake, California, October 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. MeHg, methylmercury; HgT, total mercury. cm, centimeter; ng/g, nanograms per 

gram; —, not determined]

Site ID

Depth below 

lake floor

(cm)

Lab ID Core

replicate

Lab

replicate

Percent 

dry

weight

Total 

mercury

(ng/g dry)

Methylmercury

(ng/g dry)

Ratio of 

MeHg to 

HgT

(percentage)

11F-B 2–3 GS 233 1 of 2 48.3 265 0.47 0.18

11F-B 2–3 GS 233 2 of 2 48.3 — 0.48 —

11F-B 3–4 GS 234 51.1 240 0.37 0.16

11F-B 4–8 GS 235 1 of 2 50.2 269 0.46 0.17

11F-B 4–8 GS 235 2 of 2 50.2 264 — —

11F-B 8–9 GS 236 51.1 218 0.32 0.14

11G-B 0–4 GS 237 42.8 246 0.68 0.28

11G-B 4–8 GS 238 49.9 251 0.32 0.13

11G-B 8–12 GS 239 48.8 244 0.48 0.20

12A-B 0–4 GS 240 36.5 245 1.4 0.58

12A-B 4–8 GS 241 48.1 248 1.4 0.55

12A-B 8–10 GS 242 49.7 251 0.63 0.25

12B-B 0–2 GS 243 39.1 174 0.75 0.43

12B-B 2–4 GS 244 50.4 240 0.87 0.36

12B-B 4–7.5 GS 245 57.1 184 0.45 0.25

12C-B 0–2 GS 246 47.6 243 1.0 0.41

12C-B 2–4 GS 247 1 of 2 61.6 148 0.73 0.49

12C-B 2–4 GS 247 2 of 2 61.6 — 0.75 —

12C-B 4–5.5 GS 248 1 of 2 69.0 91.4 0.52 0.57

12C-B 4–5.5 GS 248 2 of 2 69.0 101 — —

12D-B 0–2 GS 249 44.8 201 1.2 0.60

12D-B 2–4 GS 250 52.3 228 1.2 0.54

12D-B 4–7 GS 251 59.1 139 0.95 0.68

12E-B 2–4 GS 252 51.9 175 1.3 0.75

12E-B 4–6 GS 253 54.0 204 0.93 0.45

13-B 0–4 GS 254 39.4 230 0.80 0.35

13-B 4–8 GS 255 49.5 240 0.41 0.17

13-B 8–12 GS 256 53.0 226 0.49 0.22

14-B 0–4 GS 257 32.9 225 0.69 0.31

14-B 4–8 GS 258 1 of 2 43.7 241 0.62 0.26

14-B 4–8 GS 258 2 of 2 43.7 — 0.70 —

14-B 8–12 GS 259 47.8 233 0.81 0.35

15-B 0–4 GS 260 31.4 263 1.0 0.39

15-B 4–8 GS 261 43.0 281 1.2 0.44

15-B 8–12 GS 262 47.9 261 1.2 0.48

16-B 0–4 GS 263 31.8 267 0.56 0.21

16-B 4–8 GS 264 46.8 258 1.4 0.54

17-B 0–4 GS 265 38.0 220 0.43 0.20

Results 29
Table 4. Mercury and methylmercury data for shallow cores taken at Englebright Lake, California, October 2002—Continued.

[Analyses by Battelle Marine Sciences Laboratory, Sequim, Wash. MeHg, methylmercury; HgT, total mercury. cm, centimeter; ng/g, nanograms per 

gram; —, not determined]

Site ID

Depth below 

lake floor

(cm)

Lab ID Core

replicate

Lab

replicate

Percent 

dry

weight

Total 

mercury

(ng/g dry)

Methylmercury

(ng/g dry)

Ratio of 

MeHg to 

HgT

(percentage)

17-B 4–8 GS 266 48.9 220 0.47 0.21

17-B 8–10 GS 267 1 of 2 53.5 200 0.43 0.22

17-B 8–10 GS 267 2 of 2 53.5 197 — —

18-B 0–4 GS 268 30.6 253 1.6 0.64

18-B 4–8 GS 269 40.6 257 1.2 0.47

18-B 8–12 GS 270 52.8 334 0.87 0.26

19-B 0–4 GS 271 38.5 241 2.3 0.96

19-B 4–8 GS 272 1 of 2 51.0 232 1.8 0.78

19-B 4–8 GS 272 2 of 2 51.0 — 1.7 —

19-B 8–10 GS 273 51.5 219 1.8 0.82

23A-B 0–1 GS 274 32.3 176 1.1 0.62

23A-B 1–2 GS 275 38.3 428 1.1 0.26

23A-B 2–3 GS 276 38.5 261 1.3 0.48

23A-B 3–4 GS 277 41.6 257 1.3 0.50

23A-B 4–8 GS 278 47.1 258 0.89 0.34

23A-B 8–10 GS 279 56.2 3,430 1.4 0.040

23A-B 0–4 GS 280 45.4 — 1.4 —

12E-B 0–2 GS-282 1 of 2 47.5 216 1.2 0.56

12E-B 0–2 GS-282 2 of 2 47.5 — 1.0 —

30 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
MERCURY, IN NANOGRAMS PER GRAM, DRY LEAD, IN MICROGRAMS PER GRAM, DRY

15 20 25 30 35 40 45

ARSENIC, IN MICROGRAMS PER GRAM, DRY

0

2

4

6

8

ANTIMONY, IN MICROGRAMS PER GRAM, DRY

0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4

CHROMIUM, IN MICROGRAMS PER GRAM, DRY

100 120 140 160 180 200 220

0

2

4

6

8

NICKEL, IN MICROGRAMS PER GRAM, DRY

40 60 80 100 120 140 160 180

ZIRCONIUM, IN MICROGRAMS PER GRAM, DRY

50 60 70 80 90 100 110

0

2

4

6

8

DEPTH BELOW RESERVOIR FLOOR, IN METERS

C. Arsenic

A. Mercury B. Lead

F. Nickel

0 100 200 300 400 500 600

0

2

4

6

8

10 20 30 40 50 60 70

D. Antimony

E. Chromium

G. Zirconium H. Grain size 

MEDIAN GRAIN SIZE, IN MILLIMETERS

1

clay silt sand

0.001 0.01 0.1

Figure 4. Deep coring profiles showing concentrations of trace metals and median grain size in sieved sediment subsamples (Y-series) from 

site 1 at Englebright Lake, California, May–June, 2002: (A) Mercury, (B) Lead, (C) Arsenic, (D) Antimony, (E) Chromium, (F) Nickel, (G) Zirconium, 

and (H) Median grain size. Grain-size data from Snyder and others (2004b). Lines represent vertical trends of concentration values. Horizontal 

error bars represent standard deviation of multiple analyses. Vertical bars show depth intervals. Sieve size 0.06 millimeter.

Results 31
ANTIMONY, IN MICROGRAMS PER GRAM, DRY

0.5 1.0 1.5 2.0 2.5 3.0 3.5

ARSENIC, IN MICROGRAMS PER GRAM, DRY

0 20 40 60 80 100 120 140 160 180

0

2

4

6

8

10

12

14

16

MERCURY, IN NANOGRAMS PER GRAM, DRY

0 100 200 300 400 500 600 700 800

0

2

4

6

8

10

12

14

16

C. Arsenic D. Antimony

A. Mercury

LEAD, IN MICROGRAMS PER GRAM, DRY

10 15 20 25 30 35 40 45

B. Lead

CHROMIUM, IN MICROGRAMS PER GRAM, DRY

60 80 100 120 140 160 180 200

0

2

4

6

8

10

12

14

16

NICKEL, IN MICROGRAMS PER GRAM, DRY

40 60 80 100 120 140 160

F. Nickel

ZIRCONIUM, IN MICROGRAMS PER GRAM, DRY

20 30 40 50 60 70 80 90

0

2

4

6

8

10

12

14

16

G. Zirconium

 MEDIAN GRAIN SIZE, IN MILLIMETERS

H. Grain size

DEPTH BELOW RESERVOIR FLOOR, IN METERS

E. Chromium

0.001 0.01 0.1 1

clay silt sand

Figure 5. Deep coring profiles showing concentrations of trace metals and median grain size in unsieved sediment subsamples (Y-series) 

from site 4 at Englebright Lake, California, May–June, 2002: (A) Mercury, (B) Lead, (C) Arsenic, (D) Antimony, (E) Chromium, (F) Nickel, (G) 

Zirconium, and (H) Median grain size. Grain-size data from Snyder and others (2004b). Lines represent vertical trends of concentration values. 

Horizontal error bars represent standard deviation of multiple analyses. Vertical bars show depth intervals. 

32 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
MERCURY, IN NANOGRAMS PER GRAM, DRY

0 200 400 600 800 1,000 1,200 1,400

0

10

20

30

40

A. Mercury

LEAD, IN MICROGRAMS PER GRAM, DRY

B. Lead

ARSENIC, IN MICROGRAMS PER GRAM, DRY

0

10

20

30

40

C. Arsenic

ANTIMONY, IN MICROGRAMS PER GRAM, DRY

D. Antimony

CHROMIUM, IN MICROGRAMS PER GRAM, DRY

60 80 100 120 140 160 180 200

0

10

20

30

40

E. Chromium

NICKEL, IN MICROGRAMS PER GRAM, DRY

F. Nickel

ZIRCONIUM, IN MICROGRAMS PER GRAM, DRY

40 60 80 100 120

G. Zirconium H. Grain size

MEDIAN GRAIN SIZE, IN MILLIMETERS

DEPTH BELOW RESERVOIR FLOOR, IN METERS

0 100 200 300 400 500 0 2 4 6 10 12 14 16

40 60 80 100 120 140 160 180

0

10

20

30

40

0.001 0.01 0.1 1

clay silt sand

0 20 40 60 140 160 180 200

Figure 6. Deep coring profiles showing concentrations of trace metals and median grain size in sieved sediment subsamples (Y-series) from 

site 7 at Englebright Lake, California, May–June, 2002: (A) Mercury, (B) Lead, (C) Arsenic, (D) Antimony, (E) Chromium, (F) Nickel, (G) Zirconium, 

and (H) Median grain size. Grain-size data from Snyder and others (2004b). Lines represent vertical trends of concentration values. Horizontal 

error bars represent standard deviation of multiple analyses. Vertical bars show depth intervals. Sieve size 0.06 millimeter.

Results 33
Figure 7. Deep coring profiles showing concentrations of trace metals and median grain size in sieved sediment subsamples (Y-series) from 

site 9 at Englebright Lake, California, May–June, 2002: (A) Mercury, (B) Lead, (C) Arsenic, (D) Antimony, (E) Chromium, (F) Nickel, (G) Zirconium, 

and (H) Median grain size. Grain-size data from Snyder and others (2004b). Lines represent vertical trends of concentration values. Horizontal 

error bars represent standard deviation of multiple analyses. Vertical bars show depth intervals. Sieve size 0.06 millimeter.

MERCURY, IN NANOGRAMS PER GRAM, DRY

0

0

5

10

15

20

200 400 600 800

60 80 100 120 140 40 60 80 100 120 140

20 40 60 80 100 120 140

160 180

25

LEAD, IN MICROGRAMS PER GRAM, DRY

ARSENIC, IN MICROGRAMS PER GRAM, DRY

0 50 100 150 200 250

0

5

10

15

20

25

ANTIMONY, IN MICROGRAMS PER GRAM, DRY

A. Mercury B. Lead

C. Arsenic D. Antimony

CHROMIUM, IN MICROGRAMS PER GRAM, DRY

0

5

10

15

20

25

NICKEL, IN MICROGRAMS PER GRAM, DRY

ZIRCONIUM, IN MICROGRAMS PER GRAM, DRY

0

5

10

15

20

25

G. Zirconium

DEPTH BELOW RESERVOIR FLOOR, IN METERS

0 1 2 3 4 5 6

E. Chromium F. Nickel

 MEDIAN GRAIN SIZE, IN MILLIMETERS

H. Grain size

0.001 0.01 0.1 1 10

clay silt

sand gravel

10 20 30 40 50 60 70 80

34 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Figure 8. Deep coring profiles showing concentrations of trace metals and median grain size in sieved sediment subsamples (Y-series) from 

site 8 at Englebright Lake, California, May–June, 2002: (A) Mercury, (B) Lead, (C) Arsenic, (D) Antimony, (E) Chromium, (F) Nickel, (G) Zirconium, and 

(H) Median grain size. Grain-size data from Snyder and others (2004b). Lines represent vertical trends of concentration values. Horizontal error bars 

represent standard deviation of multiple analyses. Vertical bars show depth intervals. Sieve size 0.06 millimeter.

MERCURY, IN NANOGRAMS PER GRAM, DRY

0

5

10

15

20

25

A. Mercury

LEAD, IN MICROGRAMS PER GRAM, DRY

B. Lead

ARSENIC, IN MICROGRAMS PER GRAM, DRY

0

5

10

15

20

25

C. Arsenic D. Antimony

ANTIMONY, IN MICROGRAMS PER GRAMS, DRY

CHROMIUM, IN MICROGRAMS PER GRAM, DRY

40 60 80 100 120 140 160 180

40 60 80 100 120 140 160 180

0

5

10

15

20

25

NICKEL, IN MICROGRAMS PER GRAM, DRY

ZIRCONIUM, IN MICROGRAMS PER GRAM, DRY

0

5

10

15

20

25

MEDIAN GRAIN SIZE, IN MILLIMETERS

E. Chromium F. Nickel

G. Zirconium H. Grain size

DEPTH BELOW RESERVOIR FLOOR, IN METERS

0

0 2 4 6 8 10 12 14 16

50 100 150 200 250 300

0 50 100 150 200 250 300

20 40 60 80 100 120

silt

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

0.001 0.01 0.1 1 10

clay sand gravel

Results 35
TOTAL MERCURY, IN NANOGRAMS PER GRAM, DRY

0

10

20

30

A

downstream 1 6 4 7 9 8 2

Y-series

Sites 10–19, 23

MEM-series

 upstream

MEDIAN GRAIN SIZE, IN MILLIMETERS

D

METHYLMERCURY, IN NANOGRAMS PER GRAM, DRY

B

METHYLMERCURY / TOTAL MERCURY, IN PERCENT

0

10

20

30

EXPLANATION

1 10 100 1,000 10,000

DEPTH BELOW RESERVOIR FLOOR, IN METERS

0.001 0.01 0.1 1 10

0.01 0.1 1 10 0.001 0.01 0.1 1 10

C

clay silt sand gravel

Shallow cores:

Deep cores:

Figure 9. Plots showing relations with depth for unsieved sediment subsamples (shallow cores and selected deep cores) at 

Englebright Lake, California, May–June, 2002: (A) Total mercury, (B) Methylmercury, (C) Ratio of methylmercury to total mercury, and 

(D) Median grain size. Results less than detection limit are indicated by a symbol at half the detection limit and an error bar from the 

axis to the detection limit. Vertical lines separate grain-size data into categories of clay, silt, sand, and gravel. Grain-size data from 

Snyder and others (2004b).

36 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 5. Statistical data showing longitudinal variation in mercury and methylmercury concentrations in sediments collected during 

2002 from Englebright Lake, California—Continued.

[Replicate analyses averaged before statistical computations. SD, standard deviation; n, number of analyses. ng/g, nanogram per gram; <, less than; —, not 

determined]

A. Total mercury concentration

(All values in ng/g, dry)

Near 

dam → Mid-reservoir → Upstream

Shallow cores

Site number 11 17 13 14 10 15 16 23, 18 12 19 All 

shallow

minimum 212 199 226 225 224 261 258 176 96 219 96 

maximum 338 220 240 241 307 281 267 3,430 251 241 3,430 

median 248 220 230 233 265 263 263 258 204 232 245 

mean 258 213 232 233 270 268 263 628 200 231 288 

SD 36 12 7 8 24 11 6 1,050 47 11 368 

n 23 3 3 3 12 3 2 9 15 3 76 

Deep cores 

MEM Series 

Site number 1 6 4 7 9 8 2

All MEM 

Series

minimum 176 94 27 15 <5 <5 13 <5 

maximum 575 584 1150 997 338 365 21 1,150 

median 355 344 245 135 80 97 17 137 

mean 369 334 281 185 122 97 17 182 

SD 200 138 213 180 113 93 6 172 

n 3 15 22 56 34 34 2 166 

Y Series

Site number 1 6 4 7 9 8

All Y Series

(S = sieved, 

<0.060 mm) S S S S

minimum 101 — 101 114 115 16 16

maximum 491 — 550 1,360 577 1,090 1,360

median 233 — 261 412 232 235 271

mean 251 — 270 410 276 295 317

SD 100 — 113 192 126 236 182

n 24 — 34 62 39 43 202

B. Methylmercury concentration

(All values in ng/g, dry)

Near 

Dam

→ Mid-reservoir → Upstream

Shallow cores

Site number 11 17 13 14 10 15 16 23, 18 12 19 All shallow

minimum 0.32 0.43 0.41 0.66 0.60 1.0 0.56 0.87 0.45 1.7 0.32

maximum 4.0 0.47 0.80 0.81 1.5 1.2 1.4 1.6 1.4 2.3 4.0

median 0.52 0.43 0.49 0.69 0.91 1.2 0.98 1.3 0.95 1.8 0.86

mean 0.86 0.44 0.57 0.72 0.92 1.1 0.98 1.2 0.96 1.9 0.96

SD 1.00 0.02 0.21 0.08 0.24 0.12 0.59 0.23 0.31 0.32 0.64

n 23 3 3 3 12 3 2 10 15 3 77

Table 5. Statistical data showing longitudinal variation in mercury and methylmercury concentrations in sediments collected during 

2002 from Englebright Lake, California.

[Replicate analyses averaged before statistical computations. SD, standard deviation; n, number of analyses. ng/g, nanogram per gram; <, less than; 

—, not determined]

Results 37
Table 5. Statistical data showing longitudinal variation in mercury and methylmercury concentrations in sediments collected during 

2002 from Englebright Lake, California—Continued.

[Replicate analyses averaged before statistical computations. SD, standard deviation; n, number of analyses. ng/g, nanogram per gram; <, less than; —, not 

determined]

B. Methylmercury concentration—Continued

(All values in ng/g, dry)

Near 

Dam

→ Mid-reservoir → Upstream

Deep cores

MEM Series

 Site number 1 6 4 7 9 8 2

All MEM 

Series

minimum 0.098 0.063 0.060 <0.007 <0.007 <0.007 0.051 <0.007

maximum 1.5 3.6 3.3 6.8 2.3 0.97 0.065 6.8

median 0.77 0.76 0.90 0.43 0.22 0.12 0.058 0.37

mean 0.79 1.0 1.0 0.77 0.47 0.24 0.058 0.64

SD 0.70 0.92 0.78 1.1 0.63 0.28 0.010 0.84

n 3 15 22 56 34 34 2 166

C. Ratio of methylmercury to total mercury

(All values in percent)

Near 

Dam → Mid-reservoir → Upstream

Shallow cores

 Site number 11 17 13 14 10 15 16 23, 18 12 19 All shallow

minimum 0.11 0.20 0.17 0.27 0.21 0.39 0.21 0.04 0.25 0.75 0.04

maximum 1.8 0.22 0.35 0.35 0.51 0.48 0.54 0.64 0.75 0.96 1.8

median 0.20 0.21 0.22 0.31 0.34 0.44 0.38 0.47 0.52 0.82 0.33

mean 0.35 0.21 0.24 0.31 0.34 0.44 0.38 0.40 0.49 0.84 0.40

SD 0.44 0.01 0.09 0.04 0.08 0.05 0.23 0.19 0.14 0.11 0.28

n 23 3 3 3 12 3 2 9 15 3 76

Deep cores

MEM Series

 Site number 1 6 4 7 9 8 2

All MEM 

Series

minimum 0.060 0.050 0.050 <0.03 <0.03 <0.13 0.31 <0.03

maximum 0.42 0.62 5.1 5.2 1.7 0.78 0.40 5.2

median 0.13 0.23 0.33 0.34 0.22 0.16 0.36 0.25

mean 0.20 0.25 0.62 0.51 0.35 0.24 0.36 0.41

SD 0.19 0.17 1.06 0.74 0.35 0.20 0.064 0.62

n 3 15 22 56 32 33 2 163

38 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 6. Statistical data showing vertical variation in the mercury and methylmercury concentrations of sediments collected during 

2002 from Englebright Lake, California—Continued.

[Replicate analyses averaged before statistical computations. blf, below lake floor; SD, standard deviation; n, number of analyses. ng/g, nanograms per gram; 

cm, centimeter; m, meter; mm, millimeter; >, greater than. 0–4 cm (0–4), intervals exactly 0–4 cm blf; 0–4 cm (all), all intervals within 0–4 cm blf including 

0–1, 1–2, 0–2, 2–3, 3–4, 2–4, and 0–4 cm blf]

A. Total mercury concentration

(All values in ng/g, dry)

Shallow cores (all sites) All

Depth (blf) 0–2 cm 2–4 cm 0–4 cm 0–4 cm 4–8 cm 8–12 cm 0–12 cm

(Intervals, cm blf) (0–1, 1–2, 

0–2)

(2–3, 3–4, 

2–4) (0–4) (all) (all) (all) (all)

minimum 174 148 220 148 96 199 96

maximum 428 303 307 428 338 3,430 3,430

median 247 258 246 249 245 246 247

mean 262 246 250 252 233 446 288

SD 74 45 23 50 49 796 368

n 12 12 15 39 22 16 77

Deep cores: MEM-Series (all sites)

Depth (blf) 0–3 m 3–6 m 6–9 m 9–12 m 12–15 m 15–18 m 18–21 m 21–24 m >24 m All MEM 

Series

minimum 6 <5 10 <5 <5 38 46 58 88 <5

maximum 402 575 630 363 1,150 324 338 365 997 1,150

median 133 151 228 73 125 105 193 144 224 137

mean 149 183 212 133 214 128 192 169 292 182

SD 132 168 183 134 288 83 104 97 250 172

n 29 22 22 20 15 17 14 12 15 166

B. Methylmercury concentration

(All values in ng/g, dry)

Shallow cores (all sites) All

Depth (blf) 0–2 cm 2–4 cm 0–4 cm 0–4 cm 4–8 cm 8–12 cm 0–12 cm

(Intervals, cm blf) (0–1, 1–2, 

0–2)

(2–3, 3–4, 

2–4) (0–4) (all) (all) (all) (all)

minimum 0.69 0.37 0.40 0.37 0.32 0.32 0.32

maximum 1.5 1.3 4.0 4.0 3.8 1.8 4.0

median 1.1 0.87 0.80 1.0 0.69 0.59 0.86

mean 1.0 0.89 1.2 1.1 0.91 0.76 0.96

SD 0.21 0.32 0.95 0.63 0.76 0.41 0.64

n 12 12 15 39 22 16 77

Deep cores: MEM-Series (all sites)

Depth (blf) 0-3 m 3–6 m 6–9 m 9–12 m 12–15 m 15–18 m 18–21 m 21–24 m >24 m All MEM 

Series

minimum <0.007 0.016 0.018 <0.007 <0.007 0.072 0.080 0.036 0.042 <0.007

maximum 2.3 1.3 3.6 3.0 3.3 6.8 2.3 1.5 1.5 6.8

median 0.35 0.49 0.43 0.28 0.20 0.49 0.55 0.23 0.34 0.37

mean 0.68 0.44 0.75 0.65 0.59 0.86 0.80 0.44 0.48 0.64

SD 0.70 0.36 0.92 0.83 1.0 1.58 0.47 0.44 0.44 0.84

n 29 22 22 20 15 17 14 12 15 166

Table 6. Statistical data showing vertical variation in the mercury and methylmercury concentrations of sediments collected during 

2002 from Englebright Lake, California.

[Replicate analyses averaged before statistical computations. blf, below lake floor; SD, standard deviation; n, number of analyses. ng/g, nanograms per gram; cm, 

centimeter; m, meter; mm, millimeter; >, greater than. 0–4 cm (0–4), intervals exactly 0–4 cm blf; 0–4 cm (all), all intervals within 0–4 cm blf including 0–1, 

1–2, 0–2, 2–3, 3–4, 2–4, and 0–4 cm blf]

Results 39
Table 6. Statistical data showing vertical variation in the mercury and methylmercury concentrations of sediments collected during 

2002 from Englebright Lake, California—Continued.

[Replicate analyses averaged before statistical computations. blf, below lake floor; SD, standard deviation; n, number of analyses. ng/g, nanograms per gram; 

cm, centimeter; m, meter; mm, millimeter; >, greater than. 0–4 cm (0–4), intervals exactly 0–4 cm blf; 0–4 cm (all), all intervals within 0–4 cm blf including 

0–1, 1–2, 0–2, 2–3, 3–4, 2–4, and 0–4 cm blf]

C. Ratio of Methylmercury to Total Mercury

(All values in percent)

Shallow cores (all sites) All

Depth (blf) 0–2 cm 2–4 cm 0–4 cm 0–4 cm 4–8 cm 8–12 cm 0–12 cm

(Intervals, cm blf) (0–1, 1–2, 

0–2)

(2–3, 3–4, 

2–4) (0–4) (all) (all) (all) (all)

minimum 0.21 0.16 0.17 0.16 0.11 0.04 0.04

maximum 0.62 0.75 1.6 1.6 1.8 0.82 1.8

median 0.41 0.34 0.33 0.38 0.33 0.24 0.33

mean 0.42 0.38 0.48 0.43 0.41 0.28 0.40

SD 0.12 0.17 0.40 0.27 0.36 0.18 0.28

n 12 12 15 39 22 16 77

Deep cores: MEM-Series (all sites)

Depth (blf) 0–3 m 3–6 m 6–9 m 9–12 m 12–15 m 15–18 m 18–21 m 21–24 m >24 m All MEM 

Series

minimum <0.03 0.053 0.071 <0.03 0.010 0.085 0.062 0.054 0.018 <0.03

maximum 5.1 0.91 1.3 1.6 1.7 5.2 1.7 0.80 0.89 5.2

median 0.31 0.23 0.25 0.36 0.14 0.37 0.37 0.13 0.17 0.25

mean 0.55 0.31 0.32 0.43 0.33 0.68 0.47 0.26 0.22 0.41

SD 0.92 0.23 0.28 0.39 0.53 1.2 0.47 0.25 0.23 0.62

n 29 21 22 19 14 17 14 12 15 163

40 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 7. Statistical data showing longitudinal variation in concentrations of select trace metals in sediments collected during 2002 

from Englebright Lake, California—Continued.

[Replicate analyses averaged before statistical computations. S, sieved (<0.060 millimeter [mm]); SD, standard deviation; n, number of analyses. 

μg/g, microgram per gram; mm, millimeter; <, less than, —, not determined]

Deep Cores: Y Series Near Dam → Mid-reservoir → Upstream

A. Lead concentration

(All values in μg/g, dry)

Site number 1 6 4 7 9 8 All Y Series

S S S S

minimum 17 — 12 17 18 17 12

maximum 35 — 38 180 72 268 268

median 22 — 18 31 34 33 28

mean 23 — 20 35 38 44 33

SD 5 — 6 21 15 41 25

n 24 — 34 62 39 43 202

B. Arsenic concentration

(All values in μg/g, dry)

Site number 1 6 4 7 9 8 All Y Series

S S S S

minimum 21 — 13 27 31 17 13 

maximum 64 — 152 418 228 250 418 

median 34 — 43 87 58 54 55 

mean 37 — 54 94 67 65 69 

SD 13 — 35 60 36 45 48 

n 24 — 34 62 39 43 202 

C. Antimony concentration

(All values in μg/g, dry)

Site number 1 6 4 7 9 8 All Y Series

S S S S

minimum 1.0 — 0.8 1.0 1.1 1.2 0.8 

maximum 2.1 — 3.1 13 5.3 14 14 

median 1.5 — 1.6 2.6 2.3 2.2 2.1 

mean 1.5 — 1.7 3.0 2.4 2.8 2.4 

SD 0.3 — 0.7 1.7 0.9 2.2 1.6 

n 24 — 34 62 39 43 202 

Table 7. Statistical data showing longitudinal variation in concentrations of select trace metals in sediments collected during 2002 

from Englebright Lake, California.

[Replicate analyses averaged before statistical computations. S, sieved (<0.060 millimeter [mm]); SD, standard deviation; n, number of analyses. 

μg/g, microgram per gram; mm, millimeter; <, less than, —, not determined]

Results 41
Table 7. Statistical data showing longitudinal variation in concentrations of select trace metals in sediments collected during 2002 

from Englebright Lake, California—Continued.

[Replicate analyses averaged before statistical computations. S, sieved (<0.060 millimeter [mm]); SD, standard deviation; n, number of analyses. 

μg/g, microgram per gram; mm, millimeter; <, less than, —, not determined]

Deep Cores: Y Series Near Dam → Mid-reservoir → Upstream

D. Chromium concentration

(All values in μg/g, dry)

Site number 1 6 4 7 9 8 All Y Series

S S S S

minimum 125 — 77 80 78 68 68

maximum 196 — 181 184 164 156 196

median 150 — 130 144 123 127 134

mean 151 — 129 142 123 127 134

SD 19 — 24 23 21 17 23

n 24 — 34 62 39 43 202

E. Nickel concentration

(All values in μg/g, dry)

Site number 1 6 4 7 9 8 All Y Series

S S S S

minimum 51 — 52 49 52 47 47 

maximum 152 — 135 149 112 109 152 

median 97 — 87 100 78 68 87 

mean 99 — 87 101 77 72 87 

SD 26 — 20 24 17 17 24 

n 24 — 34 62 39 43 202 

F. Zirconium concentration

(All values in μg/g, dry)

Site number 1 6 4 7 9 8 All Y Series

S S S S

minimum 65 — 32 47 44 50 32 

maximum 98 — 80 96 120 155 155 

median 80 — 63 78 71 77 75 

mean 81 — 60 78 79 83 77 

SD 7 — 11 11 22 23 18 

n 24 — 34 62 39 43 202 

42 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Subsamples from shallow box cores taken at ten sampling 

sites in Englebright Lake (figs. 2, 3) were analyzed for HgT

and MeHg (table 4). Variations in the spatial distribution of 

HgT, MeHg, and MeHg/HgT in subsamples from shallow and 

deep cores are summarized in tables 5 (longitudinal variation, 

along the long axis of the reservoir) and 6 (vertical variation). The columns in table 5 are arranged in upstream order 

from left to right. Median values of HgT in shallow box cores 

from all ten sites ranged from 204 to 265 ng/g, and all but one 

standard deviation was relatively small, indicating that nearly 

all concentration values were in the range of 200 to 300 ng/g. 

Median values of HgT in the MEM-series showed considerable 

longitudinal variation; highest median values were for sites 1 

and 6 near the dam (355 and 344 ng/g, respectively); lowest 

median values were for the three most upstream sites (80, 97, 

and 17 ng/g for sites 9, 8, and 2, respectively); intermediate 

values were for the mid-reservoir sites (245 and 135 ng/g for 

sites 4 and 7, respectively). The longitudinal trend in median 

HgT concentration of unsieved subsamples from the deep 

cores follows the trend in median grain size; HgT concentrations increase as median grain size gets finer toward the dam 

(Snyder and others, 2004c).

Interpreting total mercury concentration in the Y-series 

subsamples will be complicated by the fact that only the fines 

(silt-clay) fraction was analyzed in profiles 1Y, 7Y, 8Y, and 

9Y, whereas the whole sediment was analyzed in profile 4Y. 

The sieved material in profiles 7Y, 8Y, and 9Y had higher 

median concentrations of HgT (232–412 ng/g) than unsieved 

subsamples (MEM-series) from the same sites (80–135 ng/g) 

(table 5). The unsieved subsamples from profile 4Y had a 

median concentration of HgT (261 ng/g) which is comparable 

to the median value for MEM-series subsamples from this 

location (245 ng/g). 

 Methylmercury concentrations in shallow cores ranged 

from 0.32 to 4.0 ng/g; the median value was 0.86 ng/g. Median 

MeHg concentrations were low in box cores from the three 

sites nearest to Englebright Dam (sites 11, 17 and 13; 0.43 to 

0.52 ng/g) compared with those for sites in the mid-reservoir 

and upstream areas (0.69 to 1.8 ng/g). In contrast, median 

MeHg concentrations in subsamples from the deep cores 

(MEM-series) were higher at sites near the dam (sites 1, 6 and 

4; 0.76 to 0.90 ng/g) than at the mid-reservoir and upstream 

locations (sites 7, 9, 8, and 2; 0.058 to 0.43 ng/g). 

The ratio MeHg/HgT (expressed as a percentage of HgT) 

showed some similarity in the trends of longitudinal variation among shallow and deep subsamples (table 5). Lowest 

median values of MeHg/HgT were for the site closest to the 

dam for both the shallow cores (site 11; 0.20 percent) and the 

deep cores (site 1; 0.13 percent). Highest median values of 

MeHg/HgT were for shallow cores at the mid-reservoir and 

upstream sites (0.31 to 0.82 percent), and for deep cores at 

two mid-reservoir sites (0.33 and 0.34 percent) and the most 

upstream site (0.36 percent). However, the upstream sites were 

not uniformly high in values of MeHg/HgT in the deep cores, 

as sites 9 and 8 had median values of 0.22 and 0.16 percent, 

respectively.

The spatial variability of HgT, MeHg, and MeHg/HgT

as a function of depth in the cores is summarized in table 6. 

There was little vertical variation in HgT within the top 12 cm 

sampled by the shallow cores, similar to the lack of longitudinal variation. In the deeper cores, vertical trends in the concentration of HgT were more apparent in the individual profiles 

(figs. 4A–8A) compared with the summary statistics based on 

absolute depth (table 6) because of the varying thickness of 

the bed sediments along the longitudinal axis of the reservoir. An analysis of reservoir stratigraphy using 137Cs dating 

(Snyder and others, in press) is providing additional insights 

into temporal variations in the deposition of Hg and other trace 

metals. The highest median concentration of MeHg was in the 

top 2 centimeters of the shallow box cores. Median concentrations of MeHg and median values of MeHg/HgT decreased 

with depth from 0–4 to 4–8 cm, and from 4–8 to 8–12 cm in 

the shallow cores (table 6). However, similar decreases were 

not systematic on a larger scale in the deep cores of the MEM 

series. The overall median of MeHg/HgT in the deep cores was 

0.25 percent, not much less than the overall median value for 

the shallow cores (0.33 percent). The persistence of MeHg at 

depth in the sediments of Englebright Lake at median concentrations of 0.20 to 0.55 ng/g indicates either preservation of 

MeHg after burial and (or) an ongoing balance between rates 

of Hg methylation and MeHg demethylation in the subsurface.

Trace and Major Elements 

Chemical analyses of trace and major elements in 

Y-series subsamples (table B5) provide information on the 

sediment geochemistry at five locations in Englebright Lake. 

Depth profiles of lead, arsenic, antimony, chromium, nickel, 

and zirconium were plotted in figures 4B–G through 8B–G. 

An interpretation of these profiles in terms of the depositional 

history of Englebright Lake sediments will be published separately; therefore only a few features of the spatial distribution 

of trace elements are described here. Longitudinal variations 

in the silt and clay fraction of select trace metals from sites 1, 

7, 9, and 8 were evaluated using statistical data compiled in 

table 7 and the plots in figures 4, 6, 7, and 8. (Data from site 4 

were not used in this comparison because the subsamples were 

not sieved prior to analysis.) 

Lead concentrations in subsamples from site 1 (near 

Englebright Dam) had a mean concentration of 23 μg/g and a 

standard deviation of 5 μg/g, and ranged from a minimum of 

17 μg/g to a maximum of 35 μg/g. In contrast, lead concentrations at the three upstream sites (7, 9, and 8) had mean values 

of 35 to 44 μg/g and much higher maximum values (72 to 

268 μg/g). The maximum lead values at the three upstream 

sites were from the deepest interval in each of the profiles. 

Median lead concentrations at the three upstream sites (31 

to 34 μg/g) were also higher than the median value at site 1 

(22 μg/g).

Results 43
The longitudinal variation of arsenic and antimony 

concentrations in the silt-clay fraction was similar to that of 

lead, in that concentrations were lower in subsamples from the 

site nearest the dam (site 1) compared with the three upstream 

locations (sites 7, 9, and 8; table 7). The mean value of arsenic 

concentration at site 1 was 37 μg/g with a standard deviation 

of 13 μg/g and a maximum value of 64 μg/g. In contrast, the 

mean arsenic concentrations in subsamples from the three 

upper locations ranged from 65 to 94 μg/g. Several subsamples 

from sites 7, 9, and 8 had arsenic concentrations greater than 

100 μg/g. The mean antimony concentration at site 1 was 

1.5 μg/g with a standard deviation of 0.3 μg/g. At the three 

upstream sites, the mean antimony values ranged from 2.4 to 

3.0 μg/g. Like lead, maximum arsenic and antimony concentrations were in the deepest subsamples from each of the three 

upstream locations.

Longitudinal trends in concentrations of chromium and 

nickel are opposite those described for lead, arsenic, and 

antimony, in that the concentrations at the two sites located 

farthest upstream (sites 9 and 8) are generally lower than those 

from the two sites located relatively downstream (sites 1 and 

7; table 7). Mean values (± standard deviation, SD) of chromium concentration were 151 ± 19 μg/g and 142 ± 23 μg/g 

at relatively downstream sites 1 and 7, respectively, whereas 

the mean values (± SD) were 123 ± 21 and 127 ± 17 μg/g at 

the relatively upstream sites 9 and 8, respectively. Maximum 

values of chromium were also higher at sites 1 and 7 (196 

and 184 ug/g respectively) compared with those for sites 9 

and 8 (164 and 156 μg/g, respectively). Nickel concentrations 

followed a trend similar to that for chromium; mean values 

(± SD) at the upstream locations (sites 9 and 8) were 77 ± 

17 μg/g and 72 ± 17 μg/g, respectively, compared with values 

from the downstream locations (sites 1 and 7) of 99 ± 26 μg/g 

and 101 ± 24 μg/g, respectively. Maximum concentrations of 

nickel were 112 and 109 μg/g at sites 9 and 8, respectively, 

compared with 152 and 149 μg/g at sites 1 and 7, respectively. 

The maximum concentrations of chromium and nickel were 

not located in the deepest intervals of sites 7, 9 and 8, in contrast to lead, arsenic, and antimony (figs. 6–8).

Mean concentrations of zirconium were in the relatively 

narrow range of 78 to 83 μg/g at the­ four reservoir sites (1, 7, 

9, and 8) where the silt-clay fraction was analyzed. Maximum 

values of zirconium concentration generally were in samples 

having relatively small median grain size. The maximum concentrations of zirconium at the upstream locations (sites 9 and 

8) were 120 and 155 ug/g, respectively, whereas maximum 

concentrations at the more downstream locations were lower 

(98 and 96 ug/g at sites 1 and 7, respectively). Zirconium 

occurs primarily in the mineral zircon (ZrSiO3), which tends to 

be silt-sized.

Mercury Methylation Potential

Results from radiotracer measurements of 203Hg(II)-

methylation potential rates for shallow and deep sediments 

from Englebright Lake are shown in table 8 and figure 10. 

Potential rates of microbial MeHg production in shallow 

sediments averaged about one percent per day (percent/d), 

whereas in deeper sediments, the rate was less than detection 

(0.01 percent/d) in five of six samples and 0.08 percent/d in 

the other. Shallow sediments also had higher average values 

of weight loss on ignition (a proxy for organic content) and 

porosity, significantly higher concentrations of most solidphase Fe species, and lower dry weight (equivalent to a higher 

moisture content) than deeper sediments (table 9). 

Sulfate reduction (SR) is the microbial process thought to 

be most responsible for Hg methylation in anoxic sediments 

(Gilmour and others, 1992), although iron-reducing bacteria 

may play a role in some environmental settings, such as Clear 

Lake, California (Fleming and others, 2006). The presence of 

active microbial SR in the shallow sediments (table 9), along 

with the high Hg-methylation rates in this zone (table 8), support this generally held view. Although we did not measure 

SR rates in deep sediments, very low Hg-methylation rates 

observed in the deep cores would be consistent with low rates 

of SR. Below a depth of 10–50 cm in freshwater systems, it 

is quite common for SR to become limited as pore-water sulfate, the primary electron acceptor for this process, becomes 

depleted. The low measured concentrations of amorphous 

Fe(III) (table 9), needed to fuel microbial Fe(III)-reduction, 

indicates that important electron acceptors needed to drive 

anaerobic microbial processes are limiting in deeper sediments 

of Englebright Lake. Loss on ignition values were higher in 

shallow sediments than deeper sediments at two of the three 

sites (deep sites 4 and 9 corresponding to shallow sites 10 and 

12, respectively); data for the third site (deep site 1 corresponding to shallow site 11) are equivocal (table 9). 

44 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table 8. Whole-sediment 203Hg(II)-methylation rate constants and calculated potential rates for shallow 

and deep sediments (MP series) from Englebright Lake, California, 2002.

[Each value for rate constant and potential rate (in bold) represents the mean of two incubated samples (kill corrected); 

absolute deviation for each measurement given in parentheses. 203Hg(II), mercury-203 radiotracer divalent inorganic mercury; SD, standard deviation. cm, centimeter; %/d, percent per day; ng/g dry sed/d, nanogram per gram dry sediment per 

day; <, less than detection limit. 203Hg-kmeth or kmeth, whole-sediment 203Hg(II)-methylation rate constant expressed as 

percentage of 203Hg(II) converted to CH3

203Hg per day, calculated as [203Hg-kmeth = ln(1-fm)/t · 100]; fm, fraction of added 203Hg(II) converted to CH3

203Hg; t, incubation time. Whole-sediment 203Hg(II)-methylation potential (MP) rate calculated 

as MP = 203Hgds - 203Hgds · e^(-kmeth · t); 203Hgds, concentration of radiotracer 203Hg(II) per gram dry sediment]

Site

Depth 

interval

(cm)

Whole-sediment 203Hg(II)-methylation rate constant, 203Hg-kmeth 

(%/d)

Whole-sediment 203Hg(II)-methylation potential rate

(ng/g dry sed/d) 

Kill-corrected 

average

Absolute 

deviation

Kill-corrected 

average

Absolute 

deviation

Shallow core samples

11 0–4 0.55 (0.45) 6.2 (5.1)

11 4–8 0.48 (0.01) 5.0 (0.1)

10 0–4 2.16 (0.12) 30.4 (1.6)

10 4–8 1.04 (0.48) 11.5 (5.3)

12 0–4 1.17 (0.32) 10.3 (2.8)

mean 1.08 12.66

SD 0.67 10.27

Deep core samples

1 244–267 0.08 (0.05) 0.19 (0.12)

1 573–625 < 0.01 < 0.02

4 673–726 < 0.01 < 0.01

4 1,515–1,595 < 0.01 < 0.02

9 1,179–1,292 < 0.01 < 0.01

9 2,439–2,486 < 0.01 < 0.01

mean < 0.02 < 0.04

SD — —

Results 45
Figure 10. Plots showing 203Hg(II)-methylation potential rate as a 

function of depth for sediments from Englebright Lake, California, 

2002: (A) Sites 1 and 11, (B) Sites 4 and 10, (C) Sites 9 and 12. 

Bar represents average of two observations. Error bars indicate 

absolute deviation. 

46 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002

0

0–4

0–4

0–4

4–8

4–8

244–267

573–625

673–726

1,515–1,595

1,179–1,292

2,439–2,486

10 20 30 35

SEDIMENT DEPTH, IN CENTIMETERS BELOW RESERVOIR FLOOR

203HG(II)-METHYLATION POTENTIAL RATE, IN

 NANOGRAMS PER GRAM DRY SEDIMENT PER DAY

Site 1

Site 11

Site 4

Site 10

Site 9

Site 12

0.2

<0.02

<0.02

<0.01

<0.01

<0.01

Shallow

Deep

Deep

Deep

Shallow

Shallow
Table 9. Chemical data for the MP series of sediment samples from Englebright Lake, California, 2002.

[35S-sulfate, sulfate with S-35 radiotracer; Fe(II), ferrous iron; Fe(III), ferric iron; nmol/g dry sed/d, nanomole per gram dry sediment per day; mg/g dry sed, milligram per gram dry sediment; μmol/g dry sed, micromole per gram dry sediment; g/cc, gram per cubic centimeter; mL PW/cc wet sed, milliliter pore water per cubic centimeter wet sediment; mg/g dry sed, microgram per gram dry sediment; ng/g dry sed, nanogram per gram dry sediment; <, less than; —, not determined]

Site

Depth 

below 

lake floor, 

in 

centimeters

35SSulfate 

reduction 

rate, 

in nmol/g 

dry sed/d

Fe(II), 

in mg/g 

dry sed

Amorphous 

Fe(III), 

in mg/g 

dry sed

 Crystalline 

Fe(III),

 in mg/g 

dry sed

Acid 

volatile

 sulfide,

in μmol/g 

dry sed

Total 

reduced 

sulfur, in 

μmol/g 

dry sed

Loss on 

ignition, 

in 

percent

Percentage 

dry 

weight

Bulk 

density, 

in g/cc 

wet sed

Porosity, 

in mL 

PW/cc wet 

sed

Total 

mercury 

(HgT), in 

μg/g dry 

sed

Methylmercury 

(MeHg), 

in ng/g 

dry sed

MeHg/

HgT, in 

percent 

Shallow core samples

11 0–4 19.7 11.4 0.40 7.5 5.8 7.8 7.4 44.5 1.32 0.73 0.27 0.87 0.3211 4–8 31.3 9.5 < 0.02 11.1 2.4 2.8 5.9 48.5 1.40 0.72 0.27 0.50 0.1910 0–4 27.8 9.8 0.27 4.9 2.5 1.7 8.8 35.2 1.22 0.79 0.28 0.95 0.3510 4–8 28.6 11.2 < 0.02 4.4 4.8 10.1 8.3 45.0 1.33 0.73 0.25 0.74 0.2912 0–4 32.0 5.7 0.18 0.1 1.9 4.4 5.2 56.5 1.46 0.63 0.22 1.08 0.50mean 27.9 9.5 < 0.15 5.6 3.5 5.4 7.1 46.0 1.35 0.72 0.26 0.83 0.32standard deviation 4.9 2.3 — 4.1 1.7 3.5 1.5 7.7 0.09 0.06 0.02 0.22 0.13

Deep core samples

1 244–267 — 3.2 0.03 1.8 — — 9.2 58.8 1.48 0.61 — — —1 573–625 — 2.4 0.04 2.0 — — 5.7 58.7 1.46 0.60 — — —4 673–726 — 4.1 0.06 < 0.01 — — 6.7 62.9 1.55 0.58 — — —4 1,515–1,595 — 3.1 0.05 0.5 — — 6.2 61.7 1.54 0.59 — — —9 1,179–1,292 — 0.4 0.05 0.4 — — 0.2 83.8 1.36 0.22 — — —9 2,439–2,486 — 0.6 0.17 — — — 3.8 63.6 1.60 0.58 — — —mean — 2.3 0.07 — — — 5.3 64.9 1.50 0.53 — — —standard deviation — 1.5 0.05 — — — 3.0 9.5 0.09 0.15 — — —

Results 47
Comparing shallow (0–4 cm depth) sediment Hg-transformation dynamics among sites 10–12 (table 8 and fig. 10), 

the mid-reservoir site (10) had the highest rate of MeHg 

production, whereas the site closest to the dam (site 11) had 

the lowest, lower than the highest site by a factor of about 

five. For the two shallow sites (10 and 11) where two depth 

intervals (0–4 cm and 4–8 cm) were sampled, the highest 

rates of MeHg production occurred in the 0–4 cm layer, by 

factors of 1.2 and 2.6 relative to the 4–8 cm interval at the 

two sites, respectively. Comparing these Hg-transformation 

rates with the other measured parameters suggests that MeHg 

production was negatively correlated with redox potential and 

positively correlated with sediment pH (fig. 11). Further, the 

ratio of methylmercury to total mercury (MeHg/HgT), which 

has been used as a proxy for the relative activity of MeHg 

production, appeared to be negatively correlated with concentrations of crystalline Fe(III) in sediment, ferrous iron (Fe(II)) 

in pore water, and DOC in pore water (fig. 12). However, the 

small number of samples (n = 5) caused the trends associated 

with MeHg production (fig. 11) and MeHg/HgT (fig. 12) to 

be somewhat tenuous. Also, because of covariation among 

these and other ancillary sediment parameters (for example, 

concentrations of crystalline iron(III) in sediment, iron(II) in 

pore water, and dissolved organic carbon in pore water; tables 

9, 10; fig. 12), it is difficult to separate out which factors ultimately control Hg methylation in this system based on the current limited number of shallow sediment observations (n = 5). 

The trend towards low rates of Hg methylation in deep 

sediments observed in the current study parallels earlier results 

from Daguerre Point Dam, located on the lower Yuba River 

(12 km downstream of Englebright Dam), where similarly low 

MeHg production rates were measured in cores ranging from 

0.6 to 9.1 m below the river bed (Hunerlach and others, 2004). 

No shallow sediments were taken from Daguerre Point Dam 

for comparison with those analyzed in the current study. However, MeHg production rates for shallow sediment (0–4 cm) 

samples collected from the Yuba River upstream (n = 3) and 

downstream (n = 3) of Daguerre Point Dam were, on average, 

about 1/50th of the rates for samples collected from shallow sediments in Englebright Lake. The primary differences 

between shallow sediments collected within Englebright Lake 

and shallow sediments collected in the lower Yuba River were 

that the former (a) had more organic material, (b) had higher 

rates of SR, and (c) were more reduced than the latter. 

Heavy Minerals

Particle-size distribution was determined for nine composite samples that were used to evaluate gold concentration 

and to observe heavy minerals microscopically (table C1). 

Heavy mineral concentrates prepared from these composite 

samples provided an opportunity to observe grains of gold, 

amalgam, and other heavy minerals such as iron sulfides. A 

photograph of heavy minerals from sample 5A is shown in 

figure 13. A series of SEM photomicrographs showing gold 

and amalgam textures from the heavy mineral concentrates is 

given in Appendix D (figs. D1–D16). The particle-size distribution and gold tenor (a mining term for concentration) were 

determined for the heavy mineral concentrates prepared from 

these composite samples (table C2). The spatial distribution of 

the gold tenor results was plotted on a longitudinal section of 

the reservoir (fig. 14). The highest values of gold tenor were 

for the four samples from sites 2 and 5/7; these values ranged 

from 270 to 840 milligrams of gold per cubic meter 

(mg Au/m3). The median value of gold tenor for the nine composite samples was 92 mg Au/m3

. For comparison, the average 

gold tenor for major hydraulic placer mines in the Sierra 

Nevada was 189 mg Au/m3 (Yeend, 1974).

Figure 11. Plots showing correlation of the 203Hg(II)-methylation potential rate for shallow sediments from Englebright Lake, 

California, 2002: (A) Redox potential, (B) pH. Redox, reduction-oxidation; R2, coefficient of determination for linear least-squares 

regression.

A B

R2 = 0.72 R2 = 0.68

2.5

2.0

1.5

1.0

0.5

 0 0

 0 20

 20

 30

 10

 40 60 80 100 6.6 6.7 6.8 6.9 7.0 7.1 7.2

Eh (OXIDATION-REDUCTION POTENTIAL), IN MILLIVOLTS

 METHYLMERCURY PRODUCTION RATE, IN PERCENT OF MERCURY  CONVERTED PER DAY

pH

203HG(II)-METHYLATION, 

 IN NANOGRAMS PER GRAM  DRY SEDIMENT PER DAY

48 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Figure 12. Plots showing correlation of the ratio of methylmercury to total mercury with forms of iron and carbon in shallow sediments 

from Englebright Lake, California, 2002. (A) Concentration of crystalline iron (III) in sediment, (B) Concentration of iron (II) in pore water, 

(C) Concentration of dissolved organic carbon in pore water. R2, coefficient of determination for linear least-squares regression.

A

B

C

0.6

0.5

0.4

0.3

0.2

0.1

 0

0.6

0.5

0.4

0.3

0.2

0.1

 0

 0 2 4 6 8 10

 10 20

 20

 30 40

 40 60 80

 50

 12

 0

0.6

0.5

0.4

0.3

0.2

0.1

 0

 0

METHYLMERCURY / TOTAL MERCURY, IN PERCENT

R2 = 0.88

R2 = 0.98

R2 = 0.90

CRYSTALLINE IRON (III), IN MILLIGRAMS PER GRAM (DRY)

IRON (II), IN MILLIGRAMS PER LITER

DISSOLVED ORGANIC CARBON, IN MILLIGRAMS PER LITER

Results 49
Table 10. Chemical data for pore water from the MP series of sediment samples from Englebright Lake, California, 2002.

[Fe(II), ferrous iron. Deep core samples were not analyzed]

 Site

Depth below 

lake floor, 

in centimeters

Sulfate, 

in micromoles 

per liter

Chloride, 

in micromoles 

per liter

Fe(II),

in milligrams 

per liter

Dissolved 

organic 

carbon, 

in milligrams 

per liter

pH

Oxidationreduction 

potential, Eh, 

in millivolts

Shallow core samples

11 0–4 18.4 0.3 22.0 42.3 6.91 84

11 4–8 21.7 0.3 40.1 67.7 6.67 83

10 0–4 31.3 0.3 12.5 40.2 7.12 36

10 4–8 9.9 0.1 18.1 52.6 6.89 44

12 0–4 33.4 0.4 5.1 18.2 6.72 71

mean 22.9 0.3 19.6 44.2 6.86 64

standard deviation 9.6 0.1 13.1 18.2 0.18 23

Figure 13. Gold and amalgam grains from heavy-mineral concentrate 5A from Englebright Lake, California.

Pyrite on gold

Limonite on gold

Partial amalgam

Mercury-rich amalgam

50 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Summary and Conclusions

Methods and results are presented for geochemical 

analyses of sediment samples from two coring campaigns at 

Englebright Lake, California, conducted by the U.S. Geological Survey: a deep coring campaign completed during May–

June 2002 and a shallow sampling campaign completed during 

October 2002. Total mercury was analyzed in 444 subsamples, 

methylmercury in 243 subsamples, and other trace and major 

elements in 202 subsamples. Quality-assurance and qualitycontrol procedures including analyses of replicate pairs of split 

subsamples (in some cases analyzed by two different laboratories), standard reference materials, blanks, and spike additions 

were used to demonstrate a high level of confidence in data 

quality for mercury, methylmercury, other trace elements, and 

major elements. 

The spatial variation of total mercury (HgT) and methylmercury (MeHg), and the ratio of MeHg to HgT were evaluated using data derived from the deep and shallow cores. 

At the three deep coring sites closest to Englebright Dam, 

concentrations of HgT were generally in the range of 100 to 

500 ng/g, dry (nanogram per gram), and the median grain size 

for most samples was in the silt range (0.004 to 0.063 mm 

[millimeter]). At the deep coring sites located farther 

upstream, the upper parts of the profile had coarser grain size; 

median values were in the sand range (0.063 to 2.0 mm), and 

concentrations of HgT in unsieved samples were lower, generally 2.0 to 100 ng/g. The lower part of the vertical profiles at 

three upstream coring sites had finer median grain size and 

higher concentrations of HgT in unsieved samples than the 

upper and middle parts of these profiles. 

Longitudinal variation in HgT concentration was more 

pronounced in deep cores than in shallow cores. Median 

values of HgT in shallow cores from all ten sampling sites 

were consistently in the range of 204 to 265 ng/g, and standard 

deviations generally were small, indicating that nearly all concentration values were in the range of 200 to 300 ng/g. Median 

values of HgT in unsieved deep cores showed considerable longitudinal variation; highest median values for HgT were found 

at sites near the dam (344 and 355 ng/g); lowest median values 

for HgT were at the three most upstream sites (17 to 97 ng/g), 

and intermediate values for HgT were at the mid-reservoir sites 

(135 and 245 ng/g).

dam spillway elevation (160.6 meters, 527 feet)

1939 Yuba River topography

ELEVATION, IN METERS

2001 lake-floor surface

2

2

4

5 7 9 3 8

1

6

SW NE

DISTANCE FROM DAM, IN METERS

180

160

140

120

100

 80

 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000

Coring locations projected onto 

pre-dam thalweg line

Measured lake-floor elevation

Cored pre-dam elevation

Gold (Au), in milligrams

per cubic meter

Au > 600

600 > Au > 200

200 > Au > 80

80 > Au 

Scale conversion to feet

50x vertical exaggeration

30 feet

6,000 feet

EXPLANATION

Figure 14. Longitudinal section showing gold tenor in composite core intervals from Englebright Lake, California, 2002. Vertical 

exaggeration 50X. 2001 lake-floor surface from Childs and others (2003); 1939 Yuba River topography from U.S. Army Corps of Engineers 

maps, digitized by Childs and others (2003). Measured lake-floor elevation and cored pre-dam elevation from deep drilling, May–June 

2002 (Childs and others, 2003; Snyder and others, 2004a).

Summary and Conclusions 51
The ratio MeHg/HgT showed less variation among adjacent locations than the MeHg concentration when shallow 

and deep samples were compared. Lowest median values of 

MeHg/HgT were for the site closest to the dam both for shallow cores (0.20 percent) and deep cores (0.13 percent). The 

highest median values of MeHg/HgT were for shallow cores 

from the mid-reservoir and upstream sites (0.31 to 0.82 percent), and for deep cores from two mid-reservoir sites (0.33 

and 0.34 percent) and the most upstream site (0.36 percent).

As expected based on observations in other freshwater 

systems, the shallowest samples (0–4 cm [centimeter] below 

the reservoir floor) had a higher median concentration of 

MeHg (1.0 ng/g) than deeper samples from the shallow cores 

(4–8 cm, 0.69 ng/g; 8–12 cm, 0.59 ng/g). The shallowest 

vertical interval had the highest value of the ratio MeHg to 

HgT (0.38 percent) also. Median concentrations of MeHg and 

median values of MeHg/HgT decreased systematically with 

depth from 0–4 to 4–8 to 8–12 cm in the shallow cores. However, similar systematic decreases were not observed at the 

meter scale in the deep cores of the MEM series. The overall 

median of the ratio MeHg/HgT in the deep cores was 0.25 

percent, not much lower than the overall median value for the 

shallow cores (0.33 percent). 

The highest potential rates of microbial mercury methylation, determined with radiotracer methods, were measured in 

shallow (0 to 8 centimeter depth) sediments (5 to 30 nanograms of mercury per gram dry sediment per day), whereas 

potential rates for samples collected from depths greater than 

500 centimeters were consistently near or below the detection 

limit of the radiotracer method. Shallow sediments also had 

higher average values of loss on ignition (a proxy for organic 

content) and porosity, significantly higher concentrations of 

most solid-phase Fe species, and lower dry weight (equivalent 

to a higher moisture content) than deeper sediments. These 

results are consistent with the direction of the observed trend 

toward lower concentrations of MeHg and lower values of 

MeHg/HgT in deep sediments compared with shallow 

sediments.

Chemical analyses of trace and major elements in bed 

sediment are presented for 202 samples of deep cores from 

five sites in Englebright Lake. The overall average values and 

standard deviations for selected trace elements were as follows 

(in micrograms per gram): antimony 2.4 ± 1.6, arsenic 69 ± 

48, chromium 134 ± 23, lead 33 ± 25, and nickel 87 ± 24.

Heavy-mineral concentrates were prepared using nine 

large-volume composite samples from deep cores taken at 

four locations in the upper- and mid-reservoir. Estimated gold 

concentrations in sediment from ranged from 38 to 840 milligrams per cubic meter. Grains of gold-mercury amalgam and 

grains of electrum (native gold), with and without mercury 

staining, were observed in the heavy-mineral concentrates.

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Appendixes

56 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Appendix A. Quality Assurance and Quality Control Data for Mercury and Methylmercury Analyses

Figure A1. Results of analysis by two laboratories of total mercury in split subsamples from Englebright Lake, California, 2002.

TOTAL MERCURY, BATTELLE LAB, IN NANOGRAMS PER GRAM (DRY)

10 100

 TOTAL MERCURY, WISCONSIN LAB, IN NANOGRAMS PER GRAM (DRY)

10

100

1,000

1,000

METHYLMERCURY, BATTELLE LAB, IN NANOGRAMS PER GRAM (DRY) 

METH

YLMERCURY, WISCONSIN LAB,

IN NANOGRAMS PER GRAM (DRY)

0.01

0.01

0.1

0.1

1

1

10

10

100%

79%

Figure A2. Results of analysis by two laboratories of methylmercury in split subsamples from Englebright Lake, California, 2002. Results 

less than detection limit are indicated by a symbol at half the detection limit and an error bar from the axis to the detection limit. 

Appendixes 57
Table A1. Total mercury concentrations in standard reference materials—Continued.

[Recovery is equal to observed value divided by certified value. %, percent; n, number of analyses. ng/g, nanogram per gram; 

—, not determined] 

Total mercury

Recovery 

(%)

Laboratory 

batch

Certified 

value 

 ng/g 

(dry)

Observed 

value

ng/g 

dry)

Standard 

deviation

ng/g 

(dry)

Laboratory: U.S. Geological Survey, Boulder, Colo.

Buffalo River Sediment 2704 1,470 1,357 15 92 1Y

Buffalo River Sediment 2704 1,470 1,342 5 91 1Y

Buffalo River Sediment 2704 1,470 1,478 5 101 1Y

Buffalo River Sediment 2704 1,470 1,464 16 100 7Y

Buffalo River Sediment 2704 1,470 1,433 11 98 7Y

Buffalo River Sediment 2704 1,470 1,427 10 97 7Y

Buffalo River Sediment 2704 1,470 1,463 11 100 7Y

Buffalo River Sediment 2704 1,470 1,427 9 97 7Y

Buffalo River Sediment 2704 1,470 1,621 40 110 7Y

Buffalo River Sediment 2704 1,470 1,425 20 97 7Y

Buffalo River Sediment 2704 1,470 1,795 6 122 7Y

Buffalo River Sediment 2704 1,470 1,588 18 108 7Y

Buffalo River Sediment 2704 1,470 1,635 8 111 7Y

Buffalo River Sediment 2704 1,470 1,735 20 118 7Y

Buffalo River Sediment 2704 1,470 1,485 16 101 9Y

Buffalo River Sediment 2704 1,470 1,564 7 106 9Y

Buffalo River Sediment 2704 1,470 1,458 21 99 9Y

Buffalo River Sediment 2704 1,470 1,603 10 109 9Y

Buffalo River Sediment 2704 1,470 1,227 10 83 9Y

Buffalo River Sediment 2704 1,470 1,483 1 101 9Y

Buffalo River Sediment 2704 1,470 1,458 16 99 9Y

Buffalo River Sediment 2704 1,470 1,447 4 98 8Y

Buffalo River Sediment 2704 1,470 1,329 26 90 8Y

Buffalo River Sediment 2704 1,470 1,604 23 109 8Y

Buffalo River Sediment 2704 1,470 1,513 29 103 8Y

Buffalo River Sediment 2704 1,470 1,347 28 92 8Y

Buffalo River Sediment 2704 1,470 1,403 42 95 8Y

mean 1,470 1,486 101

uncertainty (95% prediction interval) 70 —

standard deviation — 126 9

n 27 27

Table A1. Total mercury concentrations in standard reference materials.

[Recovery is equal to observed value divided by certified value. %, percent; n, number of analyses. ng/g, nanogram per gram; 

—, not determined] 

58 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table A1. Total mercury concentrations in standard reference materials—Continued.

[Recovery is equal to observed value divided by certified value. %, percent; n, number of analyses. ng/g, nanogram per gram; 

—, not determined] 

Total mercury

Recovery 

(%)

Laboratory 

batch

Certified 

value 

 ng/g 

(dry)

Observed 

value

ng/g 

dry)

Standard 

deviation

ng/g 

(dry)

Laboratory: Battelle Marine Sciences Laboratory, Sequim, Wash. 

IAEA 405 810 803 — 99 072503HGB

IAEA 405 810 813 — 100 072503HGB

IAEA 405 810 828 — 102 072903HGB

IAEA 405 810 820 — 101 072903HGB

IAEA 405 810 824 — 102 080803HGB

IAEA 405 810 833 — 103 080803HGB

IAEA 405 810 839 — 104 082003HGB

IAEA 405 810 825 — 102 092203HGB

IAEA 405 810 800 — 99 092203HGB

IAEA 405 810 793 — 98 092203HGB

IAEA 405 810 912 — 113 092203HGB

IAEA 405 810 870 — 107 100103HGB

IAEA 405 810 844 — 104 100103HGB

IAEA 405 810 844 — 104 100103HGB

mean 810 832 103

standard deviation 40 31 4

n 14 14

Appendixes 59
Table A2. Total mercury data for replicate sediment subsamples from Englebright Lake, California, 2002—Continued.

[R1, replicate 1; R2, replicate 2; R3, replicate 3; RPD, relative percentage difference; n, number of analyses; cm, centimeter; ng/g, nanogram per gram]

Site ID

Depth 

within 

core 

sample

(cm)

Lab ID

Type of 

replicate

(C=core, 

L=Lab)

Total mercury concentration RPD

R1

(ng/g, dry)

R2

(ng/g, dry)

R3

(ng/g, dry) R1, R2 R1, R3 R2, R3

Laboratory: U.S. Geological Survey, Boulder, Colo.

Y-series: Deep cores

1D-1H-1 94–140 1Y-4 L 208 195 6.4

1B-2E-2 0–75 1Y-8 L 202 196 3.4

1B-2E-3 80–108 1Y-11 L 366 343 6.5

1B-3E-1 0–52 1Y-16 L 258 265 2.8

1B-3E-1 90–101 1Y-19 L 253 240 251 5.1 0.8 4.5

4B-2H-1 14–124 4Y-8 C 225 243 7.9

4A-4H-2 9–95 4Y-19 C 251 680 92.1

7C-1H-2 31–97 7Y-4 L 240 281 15.8

7A-4H-2 29.5–73 7Y-21 L 589 585 0.7

7C-7H-2 68–120 7Y-34 L 477 523 9.2

7C-9H-3 0–93.5 7Y-41 L 480 488 1.7

7C-11H-1 21–70 7Y-48 L 462 446 3.6

7C-12H-2 0–40.5 7Y-57 L 332 336 1.2

7C-12H-2 69–104 7Y-59 L 259 262 0.9

7C-13H-3 61.5–99 7Y-66 L 188 194 3.3

9A-1H-2 25.5–119 9Y-2 L 292 284 3.0

9C-2H-2 0–82 9Y-7 C 211 241 13.2

9A-2H-3 56–108.5 9Y-8 L 283 258 9.5

9A-3H-2 44.5–82 9Y-13 L 145 106 31.5

9C-4H-2 48–131.5 9Y-17 C 225 263 15.6

9C-7H-2 60.5–140 9Y-27 C 444 348 24.3

9C-8H-1 0–84 9Y-28 L 376 491 26.4

9A-10H-3 94.5–135.5 9Y-35 L 192 184 3.9

9C-9H-3 41–99 9Y-37 C 151 153 1.7

8A-1H-3 127.5–150 8Y-6 L 247 263 6.2

8B-3H-2 0–136 8Y-17 C 232 221 4.7

Table A2. Total mercury data for replicate sediment subsamples from Englebright Lake, California, 2002.

[R1, replicate 1; R2, replicate 2; R3, replicate 3; RPD, relative percentage difference; n, number of analyses; cm, centimeter; ng/g, nanogram per gram]

60 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table A2. Total mercury data for replicate sediment subsamples from Englebright Lake, California, 2002—Continued.

[R1, replicate 1; R2, replicate 2; R3, replicate 3; RPD, relative percentage difference; n, number of analyses; cm, centimeter; ng/g, nanogram per gram]

Site ID

Depth 

within 

core 

sample

(cm)

Lab ID

Type of 

replicate

(C=core, 

L=Lab)

Total mercury concentration RPD

R1

(ng/g, dry)

R2

(ng/g, dry)

R3

(ng/g, dry) R1, R2 R1, R3 R2, R3

Laboratory: Battelle Marine Sciences Laboratory, Sequim, Wash. 

MEM-series: Deep cores

4C-4H-2 63–73 GS 12 L 266 231 14.1

6A-1H-2 70–80 GS 28 L 386 337 13.6

6B-2H-2 109–119 GS 34 L 453 471 3.9

7B-5H-1 95–107 GS 62 L 233 247 5.8

7C-13H-3 38–48 GS 97 L 237 210 12.3

8C-3H-1 52–61 GS 124 L 416 237 54.8

8C-7H-1 18–28 GS 132 L 128 124 3.4

9C-7H-1 70–81 GS 161 L 172 100 53.1

 Shallow cores

10F-B 4–8 GS 204, 205 C 256 243 5.2

10G-B 8–12 GS 212 C 274 237 14.5

11B-B 4–8 GS 218 L 380 295 25.2

11F-B 4–8 GS 235 L 269 264 2.1

12C-B 4–5.5 GS 248 L 91.4 101 10.1

17-B 8–10 GS 267 L 200 197 1.2

n

Mean 

RPD

Median 

RPD

All replicates 40 13.0 6.3

Laboratory replicates 31 11.0 5.8

Core replicates 9 19.9 13.2

Appendixes 61
Table A3. Methylmercury concentrations in standard reference materials—Continued.

[Recovery is equal to observed value divided by certified value. n, number of analyses; 

%, percentage; ng/g, nanogram per gram; na, not applicable]

Standard 

reference

 material

Methylmercury

Recovery 

(%) Date of analysis Certified 

value

ng/g (dry)

Observed 

value

ng/g (dry)

Laboratory: Battelle Marine Sciences Laboratory, Sequim, Wash. 

IAEA-356 5.46 4.79 88 7/14/2003

IAEA-356 5.46 4.60 84 7/15/2003

IAEA-356 5.46 4.26 78 7/16/2003

IAEA-356 5.46 4.51 83 7/18/2003

IAEA-356 5.46 4.61 84 7/22/2003

IAEA-356 5.46 3.75 69 7/23/2003

IAEA-356 5.46 4.78 88 7/31/2003

IAEA-356 5.46 4.96 91 8/6/2003

IAEA-356 5.46 4.74 87 8/8/2003

IAEA-356 5.46 3.36 62 9/3/2003

IAEA-356 5.46 4.12 75 9/4/2003

IAEA-356 5.46 4.06 74 9/5/2003

IAEA-356 5.46 2.29 42 9/12/2003

IAEA-356 5.46 3.58 66 9/16/2003

IAEA-356 5.46 2.96 54 9/18/2003

IAEA-356 5.46 3.55 65 9/23/2003

IAEA-356 5.46 4.02 74 9/24/2003

IAEA-356 5.46 3.93 72 9/25/2003

IAEA-356 5.46 3.92 72 9/26/2003

mean 5.46 4.06 74

standard deviation 0.39 0.69 13

n na 19 19

Laboratory: Battelle Marine Sciences Laboratory, Sequim, Wash. 

IAEA-405 5.49 4.95 90 7/14/2003

IAEA-405 5.49 4.56 83 7/15/2003

IAEA-405 5.49 5.19 95 7/16/2003

IAEA-405 5.49 4.13 75 7/18/2003

IAEA-405 5.49 5.22 95 7/22/2003

IAEA-405 5.49 5.07 92 7/23/2003

IAEA-405 5.49 4.42 81 7/31/2003

IAEA-405 5.49 4.55 83 8/6/2003

IAEA-405 5.49 4.54 83 8/8/2003

IAEA-405 5.49 3.93 72 9/3/2003

IAEA-405 5.49 4.31 79 9/4/2003

IAEA-405 5.49 4.41 80 9/12/2003

IAEA-405 5.49 4.48 82 9/16/2003

IAEA-405 5.49 3.45 63 9/18/2003

Table A3. Methylmercury concentrations in standard reference materials.

[Recovery is equal to observed value divided by certified value. n, number of analyses; %, percentage; 

ng/g, nanogram per gram; na, not applicable]

62 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table A3. Methylmercury concentrations in standard reference materials—Continued.

[Recovery is equal to observed value divided by certified value. n, number of analyses; 

%, percentage; ng/g, nanogram per gram; na, not applicable]

Standard 

reference

 material

Methylmercury

Recovery 

(%) Date of analysis Certified 

value

ng/g (dry)

Observed 

value

ng/g (dry)

Laboratory: Battelle Marine Sciences Laboratory, Sequim, Wash. —Continued

IAEA-405 5.49 5.15 94 9/23/2003

IAEA-405 5.49 4.97 91 9/24/2003

IAEA-405 5.49 4.66 85 9/25/2003

IAEA-405 5.49 4.66 85 9/26/2003

mean 5.49 4.59 84

standard deviation 0.53 0.47 8

n na 18 18

Laboratory: U.S. Geological Survey Laboratory, Middleton, Wisc.

IAEA-356 5.46 5.08 93 2/8/2005

IAEA-356 5.46 4.23 77 2/10/2005

IAEA-356 5.46 5.10 93 2/10/2005

IAEA-356 5.46 6.37 117 2/10/2005

IAEA-356 5.46 6.64 122 3/1/2005

IAEA-356 5.46 5.11 94 3/2/2005

IAEA-356 5.46 5.60 103 3/4/2005

IAEA-356 5.46 4.90 90 3/9/2005

IAEA-356 5.46 5.57 102 3/15/2005

IAEA-356 5.46 4.47 82 3/16/2005

IAEA-356 5.46 5.59 102 3/16/2005

IAEA-356 5.46 4.03 74 3/23/2005

IAEA-356 5.46 5.05 92 3/23/2005

IAEA-356 5.46 4.02 74 3/24/2005

IAEA-356 5.46 4.66 85 3/24/2005

IAEA-356 5.46 4.44 81 3/30/2005

IAEA-356 5.46 4.42 81 3/31/2005

IAEA-356 5.46 4.79 88 3/31/2005

mean 5.46 5.00 92

standard deviation 0.39 0.74 14

n na 18 18

Appendixes 63
Table A3. Methylmercury concentrations in standard reference materials—Continued.

[Recovery is equal to observed value divided by certified value. n, number of analyses; 

%, percentage; ng/g, nanogram per gram; na, not applicable]

Standard 

reference

 material

Methylmercury

Recovery 

(%) Date of analysis Certified 

value

ng/g (dry)

Observed 

value

ng/g (dry)

Laboratory: U.S. Geological Survey Laboratory, Middleton, Wisc.—Continued

IAEA-405 5.49 3.32 61 6/10/2004

IAEA-405 5.49 3.33 61 12/2/2004

IAEA-405 5.49 4.91 89 12/2/2004

IAEA-405 5.49 3.04 55 3/1/2005

IAEA-405 5.49 3.86 70 3/2/2005

IAEA-405 5.49 3.46 63 3/4/2005

IAEA-405 5.49 5.12 93 3/9/2005

IAEA-405 5.49 4.55 83 4/19/2005

IAEA-405 5.49 5.47 100 4/19/2005

IAEA-405 5.49 4.41 80 4/21/2005

IAEA-405 5.49 5.82 106 4/21/2005

IAEA-405 5.49 2.91 53 4/30/2005

IAEA-405 5.49 3.93 72 4/30/2005

IAEA-405 5.49 3.24 59 5/4/2005

IAEA-405 5.49 4.18 76 5/4/2005

IAEA-405 5.49 4.62 84 5/5/2005

IAEA-405 5.49 2.78 51 6/28/2005

IAEA-405 5.49 3.96 72 6/28/2005

IAEA-405 5.49 3.68 67 6/29/2005

IAEA-405 5.49 3.92 71 6/29/2005

IAEA-405 5.49 3.33 61 6/30/2005

IAEA-405 5.49 5.01 91 6/30/2005

IAEA-405 5.49 2.91 53 7/7/2005

IAEA-405 5.49 3.06 56 7/7/2005

mean 5.49 3.95 72

standard deviation 0.53 0.87 16

n na 24 24

64 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table A4. Methylmercury data for replicate sediment subsamples from Englebright Lake, California, 2002. 

[Laboratory: Battelle Marine Sciences, Sequim, Wash.; R1, replicate 1; R2, replicate 2; R3, replicate 3, R4, replicate 4. RPD, relative percentage difference; n, number of analyses. ng/g, nanogram per gram]

Site ID

Depth 

within 

core 

sample

(cm)

Lab ID

Type of 

replicate

(C = core, 

L = lab)

Methylmercury concentration RPD

R1

(ng/g, dry)

R2

(ng/g, dry)

R3

(ng/g, dry)

R4

(ng/g, dry) R1, R2 R1, R3 R2, R3 R1, R4 R2, R4 R3, R4

MEM series: Deep cores6A-1H-2 70–80 GS 28 L 1.74 1.90 1.85 8.8 6.1 2.76B-2H-1 61–71 GS 33 L 0.869 0.933 7.17B-12H-2 29–39 GS 71 L 0.0435 0.0405 7.17C-1H-2 64–74 GS 74 L 0.951 1.08 12.78A-13H-1 68–78 GS 112 L 0.141 0.147 4.28C-2H-2 52–61 GS 123 L 0.936 1.01 7.6

8C-6H-1 69–79 GS 130 L 0.0740 0.0869 16.0

9C-2H-1 16–26 GS 150 L 2.24 2.32 3.59C-9H-2 33–43 GS 165 L 0.207 0.208 0.5

 Shallow cores10F-B 4–8 GS 204, 205 C 0.472 0.802 51.810G-B 2–3 GS 209 L 0.734 0.891 19.3

10G-B 8–12 GS 212, 213 C 1.10 1.02 7.5

11A-B 4–8 GS 215 L 0.574 0.867 0.896 0.490 40.7 43.8 3.3 15.8 55.6 58.6

11C-B1, -B2 0–4 GS 220, 223 C 0.846 0.487 53.911C-B1, -B2 4–8 GS 221, 224 C 0.411 0.245 50.6

11C-B1, -B2 8–12 GS 222, 225 C 0.485 0.575 17.0

11F-B 2–3 GS 233 L 0.466 0.479 2.812C-B 2–4 GS 247 L 0.728 0.751 3.1

14-B 4–8 GS 258 L 0.621 0.699 11.8

19-B 4–8 GS 272 L 1.81 1.66 9.112E-B 0–2 GS 282 L 1.21 1.02 17.0

n Mean 

RPD

Median 

RPD

All replicates 24 19.2 10.5

Laboratory replicates 19 15.5 8.8

Core replicates 5 36.2 50.6

Appendixes 65
Table A5. Comparison of results from two laboratories for total mercury and methylmercury in split sediment subsamples from 

Englebright Lake, California, 2002. 

[Lab B: Battelle Marine Sciences Laboratory, Sequim, Wash.; Lab C: U.S. Geological Survey Laboratory, Madison, Wisc. ng/g, nanogram per gram; 

RPD, relative percentage difference; %, percent; —, not determined]

Lab ID Core 

section

Type of 

replicate

(C = core, 

L = lab)

Total 

mercury 

concentration Total 

mercury 

RPD

Total 

mercury, 

ratio of 

concentration

Methylmercury

concentration Methylmercury

RPD

Methylmercury,

ratio of 

concentration

Lab B

(ng/g, dry)

Lab C

(ng/g, dry)

Lab C: 

Lab B

(%)

Lab B

(ng/g, dry)

Lab C

(ng/g, dry)

Lab C: 

Lab B

(%)

GS 10 4C-3H-1 C 215 206 4.1 96.0 0.502 0.460 8.7 91.6

GS 20 4D-2E-1 C 182 204 11.6 112.4 0.579 0.412 33.8 71.1

GS 27 4D-6H-1 C 251 235 6.5 93.7 0.200 0.151 28.0 75.5

GS 30 6A-4E-1 C 539 539 0.1 100.1 0.430 0.273 44.8 63.4

GS 36 6D-H1-1 C 153 173 12.3 113.1 0.348 0.313 10.5 90.1

GS 53 7B-1H-1 C 361 209 53.1 58.0 3.04 2.70 11.7 88.9

GS 57 7B-3H-1 C 132 134 1.2 101.2 6.83 5.31 25.0 77.7

GS 66 7B-9H-1 C 635 583 8.6 91.7 0.504 0.382 27.5 75.9

GS 70 7B-12H-1 C 87.7 100 13.1 114.0 0.230 0.172 29.0 74.7

GS 101 8A-2H-2 C 100 89.4 11.1 89.4 0.779 0.619 22.9 79.5

GS 105 8A-7H-2 C 37.3 42.7 13.5 114.5 0.0626 < 0.10 — —

GS 115 8A-14H-2 C 365 385 5.3 105.4 0.236 0.142 49.9 60.0

GS 134 9A-1H-2 C 216 257 17.3 118.9 1.66 1.13 38.3 67.9

GS 140 9A-5H-1 C 12.0 40.7 109.0 339.5 0.0245 < 0.0941 — —

GS 147 9A-11H-1 C 65.5 57.5 13.0 87.8 0.0356 < 0.13 — —

mean 12.1 100.7 mean 27.5 76.4

median 11.1 101.2 median 27.7 75.7

66 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Appendix B. Quality Assurance, Quality Control, and Data Tables for Trace and Major Elements

Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; na, not applicable; <, less 

than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

Laboratory 

ID

Aluminum

Al

Wt%

Arsenic

As

μg/g

Barium

Ba

μg/g

Beryllium

Be

μg/g

Bismuth

Bi

μg/g

Calcium

Ca

Wt%

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 5.3 0.1 22 1 378 33 1.8 0.0 0.56 0.02 2.3 0.0 

23529 6.1 0.2 22 1 396 13 1.7 0.0 0.58 0.03 2.5 0.0 

23608 3.1 0.1 22 1 313 19 1.8 0.1 0.58 0.00 1.8 0.1 

23619 2.7 0.1 21 1 306 23 1.8 0.1 0.55 0.01 1.7 0.1 

23627 3.0 0.2 22 0 343 7 2.0 0.0 0.64 0.00 2.2 0.0 

23760 2.7 0.1 21 1 304 11 1.9 0.0 0.52 0.07 1.6 0.0 

23771 2.5 0.2 21 1 301 9 1.9 0.0 0.56 0.02 1.8 0.0 

24027 3.3 0.1 22 1 300 21 1.8 0.2 0.86 0.03 1.5 0.0 

24047 2.7 0.2 22 1 322 19 1.8 0.0 0.61 0.06 1.9 0.1 

24059 2.7 0.1 22 1 286 19 1.9 0.0 0.63 0.05 1.5 0.0 

24072 2.5 0.1 21 1 271 14 1.8 0.1 0.58 0.04 1.3 0.0 

24082 5.6 0.1 22 1 398 16 1.7 0.2 0.62 0.00 2.4 0.0 

24088 4.5 0.1 21 1 339 39 1.7 0.1 0.59 0.03 2.4 0.2 

24094 3.4 0.2 21 1 281 21 1.7 0.0 0.71 0.00 2.1 0.1 

24122 3.4 0.3 21 1 256 15 1.8 0.1 0.58 0.03 1.5 0.0 

24128 3.4 0.2 21 2 265 18 1.8 0.0 0.59 0.04 1.6 0.1 

24134 4.2 0.2 24 3 287 13 1.8 0.1 0.63 0.02 2.0 0.1 

24167 3.7 0.1 22 1 282 1 1.7 0.0 0.64 0.03 2.3 0.0 

24173 5.0 0.2 21 2 348 12 2.0 0.0 0.73 0.00 2.2 0.1 

24179 5.5 0.1 21 2 391 3 2.0 0.0 0.61 0.03 2.4 0.1 

24185 3.2 0.1 20 0 246 18 2.0 0.1 0.64 0.02 2.2 0.1 

24191 1.1 0.1 20 1 143 6 1.6 0.3 0.54 0.01 0.8 0.0 

Overall average 3.6 1.2 21 1 307 58 1.8 0.1 0.62 0.07 1.9 0.4

Certified value1 6.11 0.16 223.4 0.8 414 12 na na na na 2.60 0.03

Recovery (%) 59.4 na 291.4 na 74.2 na na na na na 73.4 na

Table B1. Concentrations of trace metals and major elements in standard reference materials.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; 

Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; 

na, not applicable; <, less than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).

2

The National Institute of Standards and Technology (2000) indicated that the orginally certified concentration for arsenic (23.4 mg/g) was too high by about 

6% in analyses made since 1996. Therefore, the concentration at the time of this study was about 22 mg/g and the corresponding recovery was 95.5%.

Appendixes 67
Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; na, not applicable; <, less 

than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

Laboratory 

ID

Cadmium

Cd

μg/g

Cerium

Ce

μg/g

Cobalt

Co

μg/g

Chromium

Cr

μg/g

Cesium

Cs

μg/g

Copper

Cu

μg/g

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 3.7 0.0 52 3 13 1 130 6 5.4 0.1 99 3 

23529 3.3 0.1 55 4 13 0 121 8 6.0 0.1 98 1 

23608 3.4 0.0 23 1 13 0 126 5 2.9 0.0 96 1 

23619 3.6 0.1 20 2 12 1 121 9 2.6 0.0 93 5 

23627 3.4 0.1 27 2 13 0 126 3 4.0 0.0 99 1 

23760 3.5 0.2 16 3 13 0 121 3 1.8 0.0 96 4 

23771 3.5 0.2 16 0 13 0 126 3 1.4 0.0 100 0 

24027 3.5 0.0 15 0 12 0 128 5 4.3 0.0 101 3 

24047 3.5 0.2 17 0 13 1 132 6 3.4 0.0 100 5 

24059 3.5 0.1 16 0 13 1 130 7 3.4 0.0 100 2 

24072 3.4 0.1 19 0 12 1 130 6 2.7 0.0 95 4 

24082 3.3 0.1 58 1 12 0 121 4 5.3 0.2 98 0 

24088 3.5 0.2 45 2 12 0 120 0 4.0 0.1 94 1 

24094 3.4 0.2 27 1 12 1 119 0 3.1 0.0 90 0 

24122 3.3 0.2 31 2 12 1 115 2 2.9 0.2 87 1 

24128 3.3 0.0 29 2 11 0 115 1 2.6 0.1 90 2 

24134 3.3 0.1 41 0 12 1 125 3 5.4 0.0 99 2 

24167 3.3 0.1 30 1 12 0 130 3 3.6 0.0 98 1 

24173 3.3 0.0 38 1 12 1 126 7 4.0 0.1 100 4 

24179 3.2 0.2 51 1 12 0 122 2 5.1 0.1 97 3 

24185 3.4 0.1 30 1 12 0 129 3 3.9 0.0 104 3 

24191 3.5 0.1 8.6 0.2 12 1 128 6 0.91 0.03 95 3 

Overall average 3.4 0.1 30 15 12 0 125 5 3.6 1.3 97 4

Certified value1 3.45 0.22 72 na 14.0 0.6 135 5 6 na 98.6 5.0

Recovery (%) 98.8 na 41.7 na 88.2 na 92.3 na 59.7 na 98.1 na

68 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).
Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; na, not applicable; <, less 

than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

Laboratory

 ID

Dysprosium

Dy

μg/g

Erbium

Er

μg/g

Europium

Eu

μg/g

Iron

Fe

Wt%

Gallium

Ga

μg/g

Gadolinium

Gd

μg/g

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 4.1 0.2 2.4 0.1 1.1 0.0 3.8 0.1 13 0 4.4 0.1 

23529 3.9 0.2 2.2 0.1 1.1 0.1 3.9 0.1 13 1 4.3 0.4 

23608 2.6 0.1 1.5 0.0 0.70 0.03 3.8 0.1 13 0 2.8 0.1 

23619 2.5 0.2 1.5 0.1 0.68 0.07 2.8 0.1 12 1 2.8 0.3 

23627 3.2 0.0 1.9 0.1 0.81 0.01 3.6 0.1 13 0 3.4 0.0 

23760 2.1 0.3 1.4 0.0 0.65 0.03 3.7 0.1 13 0 2.5 0.1 

23771 2.4 0.1 1.5 0.0 0.67 0.02 3.7 0.1 13 0 2.7 0.0 

24027 1.6 0.0 0.89 0.04 0.41 0.01 3.9 0.2 15 0 1.7 0.0 

24047 2.5 0.0 1.5 0.0 0.69 0.01 3.9 0.3 15 1 2.8 0.0 

24059 2.0 0.1 1.2 0.0 0.53 0.00 3.8 0.2 15 1 2.1 0.0 

24072 2.1 0.1 1.2 0.0 0.57 0.05 3.8 0.1 15 0 2.4 0.1 

24082 3.7 0.1 2.1 0.0 1.1 0.0 3.9 0.2 15 0 4.4 0.1 

24088 3.8 0.2 2.3 0.1 1.0 0.0 3.8 0.2 15 0 4.1 0.2 

24094 2.9 0.0 1.7 0.1 0.72 0.03 3.6 0.0 15 1 3.0 0.2 

24122 2.1 0.1 1.3 0.1 0.62 0.02 3.8 0.2 15 1 2.4 0.1 

24128 2.2 0.0 1.3 0.1 0.63 0.03 3.7 0.2 14 1 2.5 0.1 

24134 3.4 0.1 1.9 0.0 0.89 0.02 4.1 0.3 15 1 3.7 0.2 

24167 3.3 0.1 2.0 0.0 0.83 0.01 4.2 0.2 15 0 3.6 0.2 

24173 3.6 0.2 2.1 0.1 0.98 0.06 4.2 0.1 15 1 3.9 0.1 

24179 3.9 0.3 2.1 0.0 1.1 0.0 4.2 0.0 15 0 4.2 0.1 

24185 3.5 0.1 2.1 0.0 0.83 0.02 4.2 0.1 15 0 3.5 0.0 

24191 0.63 0.02 0.34 0.03 0.16 0.02 4.2 0.2 15 1 0.66 0.01 

Overall average 2.8 0.9 1.6 0.5 0.76 0.24 3.8 0.3 14 1 3.1 1.0

Certified value1 6 na na na 1.3 na 4.11 0.10 15 na na na

Recovery (%) 47.0 na na na 58.6 na 93.6 na 95.4 na na na

Appendixes 69

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).
Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; na, not applicable; <, less 

than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

Laboratory ID

Holmium

Ho

μg/g

Potassium

K 

Wt%

Lanthanum

La

μg/g

Lithium

Lu

μg/g

Lutetium

Lu

μg/g

Magnesium

Mg

Wt%

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 0.79 0.01 1.8 0.0 26 2 46 0 0.34 0.00 0.81 0.01 

23529 0.79 0.00 1.9 0.1 27 2 47 1 0.34 0.02 1.13 0.05 

23608 0.51 0.02 1.8 0.0 12 1 44 1 0.24 0.00 0.32 0.01 

23619 0.49 0.04 1.8 0.1 11 1 43 2 0.23 0.01 0.29 0.02 

23627 0.61 0.01 1.7 0.0 15 1 45 1 0.28 0.01 0.34 0.01 

23760 0.44 0.01 1.6 0.0 11 1 42 0 0.19 0.01 0.12 0.00 

23771 0.48 0.00 1.7 0.1 9.5 0.1 42 2 0.21 0.01 0.14 0.00 

24027 0.31 0.02 1.6 0.0 7.8 0.1 41 1 0.13 0.01 0.53 0.02 

24047 0.52 0.03 1.8 0.0 11 0 46 1 0.20 0.02 0.23 0.02 

24059 0.39 0.01 1.7 0.0 9.1 0.0 42 2 0.17 0.00 0.22 0.01 

24072 0.40 0.02 1.8 0.1 8.9 0.2 39 1 0.15 0.01 0.26 0.01 

24082 0.70 0.01 1.8 0.1 28 0 45 3 0.28 0.01 1.10 0.03 

24088 0.73 0.01 1.5 0.0 21 1 45 0 0.28 0.01 0.89 0.10 

24094 0.55 0.02 1.4 0.0 12 0 40 0 0.21 0.01 0.64 0.04 

24122 0.42 0.01 1.5 0.0 12 1 36 2 0.16 0.01 0.47 0.02 

24128 0.44 0.01 1.4 0.0 12 0 35 1 0.17 0.00 0.50 0.03 

24134 0.71 0.01 1.5 0.0 19 0 39 3 0.27 0.00 0.90 0.07 

24167 0.65 0.02 1.4 0.0 13 1 43 0 0.26 0.01 0.59 0.01 

24173 0.72 0.05 1.8 0.1 18 1 47 0 0.28 0.02 0.83 0.05 

24179 0.70 0.01 1.4 0.0 24 0 46 0 0.27 0.00 1.08 0.03 

24185 0.68 0.02 1.2 0.0 13 0 45 1 0.27 0.02 0.51 0.03 

0.12 0.00 1.0 0.0 2.4 0.1 29 2 0.047 0.006 0.13 0.01 

Overall average 0.55 0.17 1.6 0.2 15 7 42 4 0.23 0.07 0.55 0.33

Certified value1 na na 2.00 0.04 29 na 47.5 4.1 0.6 na 1.20 0.02

Recovery (%) na na 79.9 na 50.5 na 88.6 na 37.7 na 45.6 na

70 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).
Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; na, not applicable; <, less 

than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

Laboratory ID

Manganese

Mn

μg/g

Molybdenum

Mo

μg/g

Sodium

Na

Wt%

Neodymium

Nd

μg/g

Nickel

Ni

μg/g

Phosphorus

P 

μg/g

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 567 23 3.8 0.0 0.51 0.02 25 0 41 1 949 19 

23529 566 11 4.0 0.3 0.52 0.03 27 2 41 2 975 109 

23608 570 4 3.9 0.2 0.48 0.01 14 0 42 1 1030 26 

23619 564 22 4.3 0.2 0.49 0.03 14 0 40 3 900 48 

23627 609 13 5.3 1.3 0.59 0.01 18 1 41 1 997 28 

23760 608 19 4.4 0.4 0.52 0.00 13 2 42 1 1040 28 

23771 621 17 3.9 0.3 0.52 0.01 13 0 43 1 1040 42 

24027 565 9 4.3 0.1 0.52 0.01 9.7 0.1 43 1 939 11 

24047 573 27 4.2 0.3 0.56 0.02 14 0 45 2 969 68 

24059 570 24 4.3 0.1 0.52 0.03 11 0 42 2 982 68 

24072 561 23 3.9 0.3 0.45 0.02 12 0 41 2 972 48 

24082 547 19 5.0 1.1 0.53 0.01 28 0 40 1 947 2 

24088 526 2 3.9 0.2 0.52 0.02 24 0 39 1 1050 4 

24094 512 6 4.6 0.3 0.46 0.00 15 1 44 0 1000 59 

24122 533 30 3.9 0.3 0.34 0.01 15 1 38 0 926 34 

24128 507 9 3.9 0.2 0.33 0.03 14 0 39 1 1000 115 

24134 536 25 4.3 0.0 0.58 0.00 20 0 42 1 982 38 

24167 567 16 4.3 0.3 0.57 0.01 17 0 46 1 955 4 

24173 572 25 3.9 0.1 0.58 0.00 21 2 41 2 953 89 

24179 569 4 4.1 0.5 0.59 0.00 24 0 41 1 977 24 

24185 567 13 3.9 0.2 0.63 0.01 16 1 48 1 934 110 

24191 546 33 3.7 0.3 0.55 0.01 3.4 0.1 41 2 947 69 

Overall average 562 28 4.2 0.4 0.52 0.07 17 6 42 2 976 40

Certified value1 555 19 na na 0.547 0.014 na na 44.1 3.0 998 28

Recovery (%) 101.2 na na na 94.3 na na na 95.2 na 97.8 na

Appendixes 71

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).
Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; na, not applicable; <, less 

than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

Laboratory

 ID

Lead

Pb

μg/g

Praseodymium

Pr

μg/g

Rubidium

Rb

μg/g

Rhenium

Re

μg/g

Sulfur

S 

Wt%

Antimony

Sb

μg/g

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 160 1 6.6 0.4 71 1 < 0.002 0.001 0.42 0.01 3.7 0.1 

23529 168 1 6.8 0.5 103 7 < 0.002 0.000 0.44 0.01 3.8 0.3 

23608 160 0 3.6 0.2 36 1 < 0.002 0.002 0.45 0.02 3.7 0.2 

23619 153 8 3.4 0.3 34 2 < 0.002 0.001 0.45 0.02 3.7 0.1 

23627 162 2 4.3 0.0 35 1 0.003 0.0008 0.42 0.01 5.2 0.1 

23760 153 5 3.3 0.1 37 3 < 0.002 0.000 0.46 0.01 3.6 0.1 

23771 151 5 3.2 0.0 27 1 0.0027 0.0001 0.45 0.00 3.8 0.1 

24027 184 4 2.3 0.1 56 1 0.003 0.001 0.44 0.01 3.6 0.1 

24047 155 9 3.4 0.2 38 1 < 0.002 0.000 0.44 0.01 3.8 0.1 

24059 174 6 2.8 0.0 47 0 0.004 0.001 0.46 0.01 4.9 0.2 

24072 216 5 2.9 0.1 42 2 0.003 0.000 0.43 0.02 3.9 0.2 

24082 154 2 7.0 0.2 106 1 0.003 0.002 0.42 0.02 3.8 0.1 

24088 154 1 5.7 0.3 24 1 < 0.002 0.002 0.43 0.05 3.7 0.2 

24094 156 0 3.7 0.0 15 1 0.004 0.001 0.43 0.03 3.9 0.1 

24122 150 10 3.6 0.3 45 4 0.003 0.002 0.40 0.03 3.4 0.1 

24128 156 2 3.5 0.2 31 1 0.003 0.001 0.40 0.02 3.7 0.0 

24134 153 8 5.0 0.1 67 2 0.003 0.002 0.43 0.02 3.6 0.1 

24167 155 8 3.9 0.1 16 0 0.005 0.000 0.44 0.02 3.6 0.0 

24173 152 9 4.9 0.3 50 3 < 0.002 0.002 0.41 0.03 3.6 0.2 

24179 150 3 6.1 0.2 97 1 0.003 0.001 0.42 0.01 3.7 0.4 

24185 161 0 3.8 0.1 13 0 < 0.002 0.002 0.44 0.03 3.6 0.2 

24191 160 9 0.82 0.03 5.5 0.5 < 0.003 0.002 0.43 0.00 3.7 0.2 

Overall average 161 15 4.1 1.6 45 28 na na 0.43 0.02 3.8 0.4

Certified value1 161 17 na na 100 na na na 0.397 0.004 3.79 0.15

Recovery (%) 99.8 na na na 45.2 na na na 109.0 na 100.9 na

72 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).
Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; na, not applicable; <, less 

than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

Laboratory

 ID

Selenium

Se

μg/g

Samarium

Sm

μg/g

Strontium

Sr

μg/g

Terbium

Tb

μg/g

Tellurium

Te

μg/g

Thorium

Th

μg/g

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 2.2 0.7 5.0 0.0 123 2 0.68 0.01 0.18 0.01 16 1 

23529 1.8 0.5 5.2 0.2 130 5 0.67 0.05 0.14 0.02 17 0 

23608 < 1 0 3.0 0.0 106 5 0.45 0.02 0.17 0.06 9.2 0.1 

23619 1.5 0.8 2.9 0.1 102 7 0.42 0.04 0.17 0.02 8.5 0.4 

23627 1.9 0.8 4.1 0.1 114 2 0.55 0.05 0.25 0.00 13 0 

23760 1.6 0.4 3.0 0.1 107 4 0.37 0.05 0.19 0.01 9.2 0.3 

23771 1.5 0.8 3.1 0.1 100 2 0.42 0.00 0.18 0.04 9.7 0.1 

24027 < 1 0 1.9 0.0 113 6 0.25 0.01 0.20 0.04 7.4 0.2 

24047 < 1 1 3.1 0.2 107 1 0.44 0.01 0.22 0.04 12 1 

24059 < 1 0 2.4 0.0 114 1 0.33 0.02 0.19 0.05 8.9 0.3 

24072 < 1 1 2.6 0.0 96 2 0.34 0.01 0.12 0.03 9.2 0.2 

24082 1.9 1.4 5.5 0.1 127 4 0.66 0.01 0.21 0.05 21 0 

24088 1.6 1.2 4.7 0.0 114 4 0.62 0.01 0.14 0.03 18 1 

24094 < 1 0 3.4 0.1 97 7 0.49 0.00 0.14 0.06 12 1 

24122 < 1 0 3.0 0.2 80 3 0.39 0.00 0.17 0.03 8.8 0.6 

24128 < 1 0 3.0 0.2 75 5 0.38 0.00 0.16 0.01 10 0 

24134 8.9 13.1 4.2 0.1 90 6 0.57 0.03 0.17 0.06 16 1 

24167 4.2 6.6 3.8 0.0 91 0 0.56 0.02 0.16 0.05 13 0 

24173 < 1 4 4.4 0.4 109 6 0.62 0.02 0.14 0.02 18 0 

24179 < 1 6 4.7 0.0 128 3 0.61 0.01 0.19 0.01 20 0 

24185 < 1 2 3.7 0.1 92 7 0.55 0.01 0.17 0.04 14 0 

24191 < 1 1 0.76 0.02 62 2 0.11 0.01 0.15 0.04 2.7 0.1 

Overall average < 1 na 3.5 1.1 103 17 0.48 0.15 0.17 0.03 12 5

Certified value1 1.12 0.05 6.7 na 130 na na na na na 9.2 na

Recovery (%) na na 52.6 na 79.6 na na na na na na na

Appendixes 73

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).
Laboratory

ID

Titanium

Ti

Wt%

Thallium

Tl

μg/g

Thulium

Tm

μg/g

Uranium

U 

μg/g

Vanadium

V 

μg/g

Tungsten

W 

μg/g

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23515 0.43 0.03 0.97 0.16 0.34 0.00 3.0 0.1 91 3 1.6 0.0 

23529 0.42 0.01 0.87 0.03 0.33 0.00 2.9 0.1 90 4 1.5 0.1 

23608 0.45 0.02 0.80 0.01 0.22 0.01 3.0 0.0 94 4 1.6 0.1 

23619 0.44 0.03 0.78 0.03 0.22 0.01 3.1 0.1 93 6 1.8 0.1 

23627 0.44 0.02 0.88 0.08 0.27 0.01 3.0 0.1 92 2 1.6 0.1 

23760 0.44 0.01 0.85 0.02 0.19 0.00 3.0 0.0 90 5 2.0 0.1 

23771 0.44 0.01 0.79 0.01 0.21 0.00 3.0 0.2 91 3 1.6 0.1 

24027 0.43 0.01 0.85 0.07 0.12 0.00 3.0 0.1 92 3 1.7 0.1 

24047 0.45 0.01 0.89 0.02 0.21 0.01 3.1 0.1 95 3 1.6 0.0 

24059 0.45 0.02 0.89 0.03 0.16 0.00 3.0 0.1 96 5 1.5 0.1 

24072 0.43 0.02 0.84 0.02 0.17 0.00 2.9 0.1 92 3 1.9 0.0 

24082 0.34 0.01 0.84 0.07 0.29 0.01 2.8 0.2 90 1 1.4 0.0 

24088 0.44 0.05 0.85 0.11 0.32 0.00 3.0 0.1 95 11 1.6 0.1 

24094 0.45 0.01 0.85 0.05 0.23 0.00 3.1 0.1 100 1 1.6 0.1 

24122 0.39 0.02 0.80 0.08 0.17 0.02 2.9 0.1 91 5 1.5 0.0 

24128 0.40 0.03 0.83 0.04 0.18 0.01 2.8 0.0 90 7 1.5 0.0 

24134 0.40 0.02 1.0 0.3 0.28 0.00 2.7 0.1 91 7 1.7 0.0 

24167 0.41 0.00 0.83 0.03 0.28 0.01 2.8 0.0 91 0 1.6 0.0 

24173 0.39 0.02 0.86 0.10 0.29 0.01 3.0 0.0 89 5 1.5 0.1 

24179 0.36 0.01 0.85 0.02 0.30 0.01 2.9 0.1 93 5 1.3 0.0 

24185 0.42 0.03 0.81 0.07 0.28 0.01 3.1 0.1 94 7 1.5 0.1 

24191 0.42 0.02 0.74 0.05 0.052 0.002 2.9 0.2 92 3 1.5 0.1 

Overall average 0.42 0.03 0.85 0.06 0.23 0.07 3.0 0.1 92 3 1.6 0.1

Certified value 0.457 0.018 1.06 0.07 na na 3.13 0.13 95 4 na na

Recovery (%) 92.0 na 80.1 na na na 94.3 na 97.1 na na na

Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. Wt%, weight percent; 

Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. mg/g, microgram per gram; 

na, not applicable; <, less than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. Standard 

deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as Average value divided by Certified value]

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).

74 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Laboratory 

ID

Yttrium

Y 

μg/g

Ytterbium

Yb

μg/g

Zinc

Zn

μg/g

Zirconium

Zr

μg/g

Avg SD Avg SD Avg SD Avg SD

23515 23 1 2.4 0.0 410 10 152 5 

23529 20 0 2.2 0.1 407 17 136 9 

23608 14 0 1.5 0.0 414 2 151 6 

23619 13 1 1.5 0.1 409 18 151 11 

23627 16 0 1.9 0.0 413 1 179 4 

23760 11 0 1.2 0.0 443 1 172 6 

23771 11 0 1.4 0.0 428 0 166 2 

24027 7.5 0.1 0.88 0.04 412 2 164 7 

24047 13 1 1.5 0.1 444 6 158 11 

24059 11 0 1.1 0.0 470 6 161 8 

24072 9.3 0.4 1.1 0.0 416 14 147 7 

24082 20 0 2.1 0.1 407 0 121 1 

24088 20 0 2.2 0.1 399 4 146 1 

24094 13 1 1.6 0.1 395 2 142 1 

24122 8.7 0.5 1.2 0.1 393 0 123 7 

24128 10 1 1.3 0.0 397 3 133 2 

24134 17 1 1.9 0.0 413 8 138 4 

24167 16 1 2.1 0.0 411 3 173 5 

24173 17 1 2.1 0.0 422 21 146 8 

24179 19 0 2.0 0.0 415 11 132 3 

24185 17 0 2.0 0.0 410 7 185 1 

24191 2.6 0.2 0.37 0.02 417 4 164 7 

Overall average 14 5 1.6 0.5 416 18 152 18

Certified value na na 2.8 na 438 12 300 na

Recovery (%) na na 58.0 na 94.9 na 50.6 na

Table B1. Concentrations of trace metals and major elements in standard reference materials—Continued.

[Standard reference material is Buffalo River Sediment (NIST 2704). NIST, National Institute of Standards and Technology. 

Wt%, weight percent; Avg, average concentration from three or more replicate measurements of single digestate; SD, standard deviation. 

mg/g, microgram per gram; na, not applicable; <, less than.

Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single 

digestate. Standard deviation on “Overall average” row represents standard deviation of individual analyses. Recovery computed as 

Average value divided by Certified value]

1

Non-bold numbers are not certified and are provided for information only (National Institute of Standards and Technology, 1990).

Appendixes 75
Table B2. Data for trace metals and major elements in digestion blanks—Continued.

[Averages (Avg) and standard deviations (SD) are for three or more replicate analyses of single digested subsample. Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. μg/L, microgram per liter; mg/L, milligram per liter; 

<, less than]

Laboratory

ID

Aluminum

Al

μg/L

Arsenic

As

μg/L

Barium

Ba

μg/L

Beryllium

Be

μg/L

Bismuth

Bi

μg/L

Calcium

Ca

mg/L

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23520 15 1 < 0.1 0.1 < 0.7 0.2 < 0.04 0.01 0.014 0.019 < 0.07 0.03 

23530 105 5 < 0.1 0.2 < 0.7 0.2 < 0.04 0.02 0.043 0.025 < 0.07 0.04 

23611 176 6 < 0.1 0.1 < 0.7 0.2 < 0.04 0.02 0.038 0.010 < 0.07 0.02 

23621 23 1 < 0.1 0.1 0.7 1.2 < 0.04 0.01 0.040 0.020 < 0.07 0.04 

23631 92 4 < 0.1 0.1 1.1 1.2 < 0.04 0.02 0.063 0.060 0.09 0.00 

23767 118 7 0.2 0.5 0.9 0.4 < 0.04 0.02 0.024 0.001 < 0.07 0.02 

23777 49 1 < 0.1 0.2 < 0.7 1.0 < 0.04 0.01 < 0.008 0.002 < 0.07 0.00 

24031 72 3 < 0.1 0.1 < 0.7 0.1 < 0.04 0.02 0.042 0.016 < 0.07 0.02 

24053 121 3 < 0.1 0.1 1.3 0.4 < 0.04 0.01 0.032 0.005 0.09 0.02 

24063 66 2 < 0.1 0.1 < 0.7 0.1 < 0.04 0.00 0.038 0.034 < 0.07 0.01 

24083 302 8 1.1 1.4 1.3 0.2 < 0.04 0.03 0.085 0.056 0.10 0.02 

24089 54 2 0.2 0.3 < 0.7 0.1 < 0.04 0.02 0.030 0.016 < 0.07 0.02 

24095 153 10 0.4 0.8 2.1 0.4 < 0.04 0.01 0.032 0.003 < 0.07 0.02 

24174 336 15 2.4 3.2 0.7 0.1 < 0.04 0.04 0.092 0.016 < 0.07 0.04 

24186 609 11 < 0.1 0.3 0.9 0.2 < 0.04 0.03 0.15 0.02 < 0.07 0.01 

24192 181 6 0.3 0.6 2.0 0.1 < 0.04 0.01 0.024 0.008 < 0.07 0.03 

Laboratory 

ID

Cadmium

Cd

μg/L

Cerium

Ce

μg/L

Cobalt

Co

μg/L

Chromium

Cr

μg/L

Cesium

Cs

μg/L

Copper

Cu

μg/L

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23520 0.05 0.01 0.026 0.002 < 0.03 0.01 < 0.9 0.1 < 0.03 0.04 0.3 0.1 

23530 0.03 0.01 0.084 0.007 < 0.03 0.00 < 0.9 1.1 < 0.03 0.01 < 0.3 0.1 

23611 0.12 0.01 0.059 0.006 < 0.03 0.00 < 0.9 0.6 < 0.03 0.02 0.7 0.0 

23621 0.02 0.00 0.019 0.003 < 0.03 0.00 < 0.9 0.9 0.05 0.03 0.5 0.2 

23631 < 0.02 0.01 0.042 0.004 < 0.03 0.01 < 0.9 0.3 < 0.03 0.01 < 0.3 0.3 

23767 0.05 0.02 0.033 0.001 < 0.03 0.00 < 0.9 0.8 < 0.03 0.02 1.1 0.6 

23777 0.02 0.01 0.013 0.001 < 0.03 0.01 < 0.9 1.3 < 0.03 0.04 < 0.3 0.1 

24031 0.02 0.01 0.051 0.001 0.08 0.01 2.9 0.6 0.57 0.02 1.5 0.2 

24053 0.04 0.01 0.055 0.006 < 0.03 0.01 < 0.9 0.2 < 0.03 0.03 0.4 0.3 

24063 < 0.02 0.00 0.034 0.005 0.03 0.01 1.6 0.5 < 0.03 0.03 0.4 0.4 

24083 < 0.02 0.01 0.23 0.01 < 0.03 0.01 < 0.9 1.8 0.04 0.01 < 0.3 0.1 

24089 < 0.02 0.01 0.047 0.008 < 0.03 0.01 1.1 1.3 < 0.03 0.02 < 0.3 0.1 

24095 0.02 0.00 0.11 0.09 < 0.03 0.00 < 0.9 1.5 1.3 0.0 < 0.3 0.0 

24174 < 0.02 0.02 0.058 0.007 < 0.03 0.03 < 0.9 1.2 0.13 0.03 < 0.3 0.3 

24186 0.02 0.00 0.094 0.017 < 0.03 0.01 < 0.9 1.7 0.06 0.01 < 0.3 0.1 

24192 0.05 0.01 0.071 0.028 < 0.03 0.01 0.9 1.6 0.28 0.01 < 0.3 0.0 

Table B2. Data for trace metals and major elements in digestion blanks.

[Averages (Avg) and standard deviations (SD) are for three or more replicate analyses of single digested subsample. Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. μg/L, microgram per liter; mg/L, milligram per liter; 

<, less than]

76 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table B2. Data for trace metals and major elements in digestion blanks—Continued.

[Averages (Avg) and standard deviations (SD) are for three or more replicate analyses of single digested subsample. Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. μg/L, microgram per liter; mg/L, milligram per liter; 

<, less than]

Laboratory

ID

Dysprosium

Dy

μg/L

Erbium

Er

μg/L

Europium

Eu

μg/L

Iron

Fe

μg/L

Gallium

Ga

μg/L

Gadolinium

Gd

μg/L

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23520 < 0.003 0.002 < 0.004 0.001 < 0.002 0.000 < 50 4 < 0.007 0.002 < 0.004 0.001 

23530 0.008 0.003 0.005 0.001 0.004 0.002 66 76 < 0.007 0.004 0.006 0.003 

23611 0.004 0.002 0.009 0.001 < 0.002 0.000 < 50 14 < 0.007 0.012 0.004 0.001 

23621 < 0.003 0.002 < 0.004 0.000 < 0.002 0.001 < 50 100 0.010 0.008 0.005 0.004 

23631 0.004 0.004 < 0.004 0.002 < 0.002 0.001 < 50 41 0.009 0.003 < 0.004 0.001 

23767 0.004 0.000 < 0.004 0.003 < 0.002 0.002 60 31 < 0.007 0.004 < 0.004 0.002 

23777 < 0.003 0.002 < 0.004 0.002 < 0.002 0.000 52 52 0.010 0.004 < 0.004 0.001 

24031 0.003 0.004 < 0.004 0.001 0.002 0.001 97 22 < 0.007 0.005 < 0.004 0.001 

24053 0.004 0.004 < 0.004 0.002 0.002 0.001 < 50 28 0.012 0.006 < 0.004 0.005 

24063 < 0.003 0.004 < 0.004 0.003 < 0.002 0.000 < 50 8 < 0.007 0.005 < 0.004 0.006 

24083 0.014 0.006 0.011 0.008 0.005 0.003 < 50 44 < 0.007 0.004 0.018 0.009 

24089 < 0.003 0.002 < 0.004 0.001 < 0.002 0.000 54 39 < 0.007 0.004 < 0.004 0.001 

24095 0.003 0.001 < 0.004 0.003 < 0.002 0.002 < 50 48 < 0.007 0.005 < 0.004 0.004 

24174 0.006 0.004 < 0.004 0.005 0.003 0.002 162 33 < 0.007 0.017 0.008 0.003 

24186 0.009 0.003 0.010 0.007 0.003 0.001 149 22 < 0.007 0.015 0.010 0.005 

24192 0.004 0.007 0.006 0.004 < 0.002 0.001 < 50 56 < 0.007 0.011 0.006 0.004 

Laboratory

ID

Holmium

Ho

μg/L

Potassium

K 

mg/L

Lanthanum

La

μg/L

Lithium

Li

μg/L

Lutetium

Lu

μg/L

Magnesium

Mg

mg/L

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23520 < 0.0010 0.001 < 0.09 0.03 0.014 0.002 < 0.1 0.1 < 0.0010 0.000 0.005 0.004 

23530 0.002 0.000 < 0.09 0.06 0.039 0.006 < 0.1 0.1 < 0.0010 0.000 0.006 0.010 

23611 0.001 0.001 < 0.09 0.03 0.029 0.002 < 0.1 0.0 < 0.0010 0.000 0.030 0.045 

23621 < 0.0010 0.001 < 0.09 0.06 0.009 0.003 < 0.1 0.2 < 0.0010 0.001 < 0.004 0.000 

23631 < 0.0010 0.001 < 0.09 0.04 0.020 0.001 < 0.1 0.1 < 0.0010 0.001 0.009 0.007 

23767 0.001 0.000 0.15 0.21 0.015 0.000 0.2 0.2 0.001 0.001 0.004 0.003 

23777 < 0.0010 0.000 < 0.09 0.05 0.006 0.002 0.1 0.2 < 0.0010 0.000 < 0.004 0.002 

24031 < 0.0010 0.000 0.12 0.10 0.027 0.001 0.2 0.1 < 0.0010 0.000 0.035 0.011 

24053 < 0.0010 0.001 < 0.09 0.09 0.031 0.001 < 0.1 0.1 < 0.0010 0.000 0.025 0.004 

24063 < 0.0010 0.001 < 0.09 0.08 0.021 0.002 < 0.1 0.2 < 0.0010 0.000 0.023 0.020 

24083 0.003 0.001 0.10 0.07 0.12 0.01 < 0.1 0.0 0.001 0.000 0.053 0.034 

24089 0.001 0.000 < 0.09 0.04 0.020 0.006 < 0.1 0.1 < 0.0010 0.001 0.004 0.005 

24095 < 0.0010 0.001 < 0.09 0.08 0.060 0.064 0.2 0.0 < 0.0010 0.001 0.020 0.030 

24174 0.001 0.001 < 0.09 0.01 0.031 0.003 0.3 0.1 < 0.0010 0.001 < 0.004 0.000 

24186 0.003 0.002 < 0.09 0.01 0.043 0.011 0.5 0.1 0.002 0.001 0.013 0.015 

24192 < 0.0010 0.000 < 0.09 0.09 0.028 0.012 < 0.1 0.04 < 0.0010 0.001 0.010 0.002 

Appendixes 77
Table B2. Data for trace metals and major elements in digestion blanks—Continued.

[Averages (Avg) and standard deviations (SD) are for three or more replicate analyses of single digested subsample. Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. μg/L, microgram per liter; mg/L, milligram per liter; 

<, less than]

Laboratory

ID

Manganese

Mn

μg/L

Molybdenum

Mo

μg/L

Sodium

Na

mg/L

Neodymium

Nd

μg/L

Nickel

Ni

μg/L

Phosphorus

P 

μg/L

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23520 < 0.6 0.7 < 0.3 0.1 < 0.02 0.02 0.018 0.008 < 0.1 0.1 < 50 18 

23530 < 0.6 0.5 < 0.3 0.2 0.20 0.03 0.053 0.003 0.1 0.0 < 50 28 

23611 1.1 0.5 < 0.3 0.0 0.29 0.02 0.023 0.010 0.1 0.1 < 50 11 

23621 < 0.6 0.2 < 0.3 0.2 0.08 0.01 0.011 0.002 0.3 0.0 < 50 23 

23631 < 0.6 0.3 < 0.3 0.2 0.17 0.01 0.013 0.003 < 0.1 0.0 < 50 40 

23767 0.8 0.1 0.8 0.1 0.33 0.09 < 0.009 0.002 0.5 0.2 < 50 37 

23777 < 0.6 0.1 < 0.3 0.2 0.08 0.03 < 0.009 0.001 0.3 0.1 < 50 44 

24031 0.8 0.3 0.7 0.3 0.20 0.08 0.021 0.005 1.2 0.1 < 50 60 

24053 < 0.6 0.1 < 0.3 0.1 0.28 0.02 0.022 0.007 7.3 0.3 < 50 27 

24063 < 0.6 0.1 < 0.3 0.1 0.19 0.06 0.016 0.005 0.9 0.2 < 50 29 

24083 0.7 0.2 0.8 1.2 0.25 0.07 0.12 0.02 0.9 0.1 < 50 21 

24089 < 0.6 0.2 1.4 0.1 0.04 0.01 0.027 0.014 0.2 0.0 < 50 16 

24095 < 0.6 0.1 < 0.3 0.3 0.31 0.02 0.060 0.070 0.6 0.0 < 50 34 

24174 < 0.6 0.8 0.3 0.3 0.85 0.06 0.025 0.009 1.0 0.1 < 50 7 

24186 < 0.6 0.5 < 0.3 0.4 1.5 0.1 0.030 0.014 0.7 0.2 < 50 33 

24192 0.8 0.1 < 0.3 0.2 0.09 0.03 0.025 0.008 0.3 0.1 < 50 26 

Laboratory

ID

Lead

Pb

μg/L

Praseodymium

Pr

μg/L

Rubidium

Rb

μg/L

Rhenium

Re

μg/L

Sulfur

S 

mg/L

Antimony

Sb

μg/L

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23520 < 0.1 0.1 0.004 0.001 < 0.06 0.04 < 0.002 0.000 < 0.2 0.1 0.04 0.02 

23530 0.2 0.1 0.011 0.001 < 0.06 0.02 < 0.002 0.001 < 0.2 0.1 0.05 0.07 

23611 0.2 0.1 0.008 0.001 < 0.06 0.02 < 0.002 0.001 < 0.2 0.1 0.06 0.01 

23621 < 0.1 0.0 0.004 0.001 < 0.06 0.02 < 0.002 0.001 < 0.2 0.1 0.03 0.03 

23631 < 0.1 0.1 0.005 0.002 < 0.06 0.03 < 0.002 0.001 < 0.2 0.1 0.05 0.05 

23767 0.1 0.1 0.004 0.001 0.14 0.15 < 0.002 0.001 < 0.2 0.0 0.29 0.01 

23777 < 0.1 0.0 < 0.002 0.000 < 0.06 0.04 < 0.002 0.001 < 0.2 0.1 0.03 0.07 

24031 0.4 0.1 0.008 0.002 0.11 0.04 < 0.002 0.001 < 0.2 0.1 0.05 0.02 

24053 0.1 0.0 0.006 0.000 0.08 0.04 < 0.002 0.001 < 0.2 0.1 0.02 0.01 

24063 0.2 0.0 0.004 0.000 0.14 0.04 < 0.002 0.002 < 0.2 0.1 0.07 0.00 

24083 0.3 0.2 0.030 0.003 0.22 0.04 < 0.002 0.001 < 0.2 0.0 0.14 0.10 

24089 0.1 0.1 0.005 0.001 < 0.06 0.01 < 0.002 0.000 < 0.2 0.2 0.04 0.02 

24095 0.4 0.0 0.016 0.019 0.07 0.04 < 0.002 0.001 < 0.2 0.1 0.38 0.03 

24174 0.1 0.1 0.007 0.001 0.13 0.06 < 0.002 0.000 < 0.2 0.1 0.09 0.01 

24186 0.2 0.1 0.013 0.003 0.15 0.03 < 0.002 0.002 < 0.2 0.0 0.15 0.05 

24192 < 0.1 0.1 0.006 0.002 < 0.06 0.0 < 0.002 0.001 < 0.2 0.1 0.02 0.01 

78 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table B2. Data for trace metals and major elements in digestion blanks—Continued.

[Averages (Avg) and standard deviations (SD) are for three or more replicate analyses of single digested subsample. Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. μg/L, microgram per liter; mg/L, milligram per liter; 

<, less than]

Laboratory

ID

Selenium

Se

μg/L

Samarium

Sm

μg/L

Strontium

Sr

μg/L

Terbium

Tb

μg/L

Tellurium

Te

μg/L

Thorium

Th

μg/L

Avg SD Avg SD Avg SD Avg SD Avg SD Avg SD

23520 < 0.8 0.4 < 0.008 0.004 < 0.1 0.0 < 0.0008 0.001 < 0.04 0.03 0.007 0.003 

23530 < 0.8 0.8 0.014 0.003 < 0.1 0.0 0.001 0.001 < 0.04 0.04 0.11 0.10 

23611 < 0.8 0.8 < 0.008 0.001 0.2 0.1 0.001 0.001 < 0.04 0.02 0.046 0.006 

23621 < 0.8 0.4 < 0.008 0.005 0.6 0.7 < 0.0008 0.000 < 0.04 0.04 0.069 0.110 

23631 < 0.8 1.2 < 0.008 0.003 0.4 0.7 < 0.0008 0.000 < 0.04 0.00 0.11 0.13 

23767 < 0.8 1.8 < 0.008 0.003 0.2 0.1 < 0.0008 0.000 < 0.04 0.02 0.11 0.13 

23777 < 0.8 0.1 < 0.008 0.004 0.2 0.0 < 0.0008 0.001 < 0.04 0.00 0.10 0.17 

24031 < 0.8 1.5 < 0.008 0.002 < 0.1 0.1 0.001 0.001 < 0.04 0.02 0.033 0.007 

24053 < 0.8 0.3 < 0.008 0.002 0.4 0.4 0.001 0.001 < 0.04 0.02 0.041 0.013 

24063 < 0.8 0.4 < 0.008 0.005 < 0.1 0.1 < 0.0008 0.000 < 0.04 0.01 0.030 0.016 

24083 5.7 1.5 0.024 0.007 1.0 0.7 0.002 0.001 0.04 0.02 0.37 0.20 

24089 < 0.8 0.9 < 0.008 0.006 < 0.1 0.1 0.001 0.001 < 0.04 0.02 0.038 0.011 

24095 < 0.8 0.4 0.011 0.005 0.2 0.2 < 0.0008 0.001 < 0.04 0.02 0.072 0.031 

24174 8.2 11.8 < 0.008 0.001 0.3 0.2 < 0.0008 0.000 < 0.04 0.04 0.060 0.014 

24186 < 0.8 2.1 < 0.008 0.001 0.4 0.0 0.001 0.001 0.05 0.01 0.092 0.014 

24192 1.0 2.5 < 0.008 0.001 0.3 0.1 < 0.0008 0.001 < 0.04 0.03 0.030 0.006 

Laboratory

ID

Titanium

Ti

μg/L

Thallium

Tl

μg/L

Thulium

Tm

μg/L

Uranium

U 

μg/L

Vanadium

V 

μg/L

Avg SD Avg SD Avg SD Avg SD Avg SD

23520 < 6 3 < 0.06 0.05 < 0.001 0.000 < 0.007 0.002 < 2 1 

23530 < 6 7 < 0.06 0.09 < 0.001 0.000 0.023 0.019 < 2 0 

23611 < 6 6 < 0.06 0.04 < 0.001 0.000 0.019 0.002 < 2 1 

23621 < 6 6 < 0.06 0.05 < 0.001 0.001 < 0.007 0.001 < 2 1 

23631 15 10 < 0.06 0.03 < 0.001 0.000 < 0.007 0.000 < 2 1 

23767 8 2 < 0.06 0.02 < 0.001 0.000 0.035 0.055 < 2 1 

23777 < 6 5 < 0.06 0.05 < 0.001 0.001 < 0.007 0.001 < 2 1 

24031 7 7 < 0.06 0.03 < 0.001 0.001 < 0.007 0.002 < 2 2 

24053 10 6 < 0.06 0.01 < 0.001 0.000 < 0.007 0.003 < 2 2 

24063 < 6 8 < 0.06 0.03 < 0.001 0.001 0.014 0.002 < 2 2 

24083 < 6 8 < 0.06 0.07 0.001 0.001 0.060 0.075 2 0 

24089 7 7 0.07 0.08 < 0.001 0.000 < 0.007 0.01 < 2 1 

24095 8 8 < 0.06 0.04 < 0.001 0.001 < 0.007 0.00 < 2 1 

24174 < 6 2 < 0.06 0.00 < 0.001 0.001 0.009 0.001 < 2 1 

24186 15 4 < 0.06 0.03 0.002 0.001 0.015 0.002 < 2 0 

24192 6 7 < 0.06 0.05 < 0.001 0.001 < 0.007 0.004 < 2 0 

Appendixes 79
Table B2. Data for trace metals and major elements in digestion blanks—Continued.

[Averages (Avg) and standard deviations (SD) are for three or more replicate analyses of single digested subsample. Standard deviation for each analysis represents standard deviation of three or more ICP (inductively coupled plasma) analyses of single digestate. μg/L, microgram per liter; mg/L, milligram per liter; 

<, less than]

Laboratory

ID

Tungsten

W 

μg/L

Yttrium

Y 

μg/L

Ytterbium

Yb

μg/L

Zinc

Zn

μg/L

Zirconium

Zr

μg/L

Avg SD Avg SD Avg SD Avg SD Avg SD

23520 < 0.02 0.01 0.011 0.002 < 0.002 0.001 4 3 0.11 0.02 

23530 < 0.02 0.01 0.044 0.007 0.004 0.001 < 2 1 2.4 0.2 

23611 < 0.02 0.00 0.037 0.001 0.005 0.001 3 1 4.0 0.2 

23621 < 0.02 0.01 0.009 0.002 < 0.002 0.004 2 1 0.40 0.20 

23631 < 0.02 0.00 0.013 0.003 0.003 0.001 7 2 2.2 0.2 

23767 < 0.02 0.01 0.018 0.003 0.004 0.002 15 4 2.4 0.1 

23777 < 0.02 0.00 0.007 0.003 < 0.002 0.001 5 1 0.73 0.29 

24031 4.9 0.1 0.017 0.004 0.004 0.002 13 4 2.1 0.1 

24053 0.16 0.01 0.020 0.000 0.003 0.002 8 3 1.7 0.0 

24063 1.6 0.0 0.015 0.005 < 0.002 0.003 8 1 1.8 0.1 

24083 0.03 0.02 0.090 0.000 0.011 0.001 13 3 2.7 0.3 

24089 < 0.02 0.01 0.021 0.006 < 0.002 0.001 5 0 1.0 0.0 

24095 < 0.02 0.01 0.026 0.008 0.005 0.002 13 6 2.8 0.1 

24174 0.03 0.01 0.039 0.009 0.007 0.005 4 1 8.8 0.4 

24186 < 0.02 0.00 0.079 0.009 0.018 0.001 6 1 16 1 

24192 < 0.02 0.01 0.020 0.013 < 0.002 0.002 4 1 1.7 0.4 

80 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table B3. Recovery data for trace-metal spikes in sediment samples from Englebright Lake, California, 2002.

[Numbers are percent recovery, computed as measured value divided by expected value; —, not determined]

Date Arsenic

As

Cadmium

Cd

Calcium

Ca

Copper

Cu

Lead

Pb

Magnesium

Mg

Zinc

Zn

7/13/2004 107 103 — 100 99 — 106 

7/16/2004 97 94 109 93 89 107 97 

7/16/2004 121 106 — 102 99 — 106 

7/30/2004 101 100 110 98 97 111 102 

8/5/2004 100 97 108 89 94 104 97 

8/6/2004 105 98 113 89 93 113 97 

Table B4. Data for trace metals and major elements in replicate sediment subsamples from Englebright Lake, California, 2002.

See Excel table B4 at App_B_TableB4.xls

Table B5. Data for trace metals and major elements from the Y series of subsamples from the May–June 2002 deep cores from 

Englebright Lake, California.

See Excel table B5 at App_B_TableB5.xls

Appendixes 81
Appendix C. Mineralogical and Grain-Size Distribution Data for Heavy Mineral Concentrates

Table C1. Particle-size distribution of bulk composite core samples prior to preparation of heavy mineral concentrates, Englebright 

Lake, California, 2002.

[mm, millimeter; g, gram; m, meter; >, greater than; <, less than]

Site

Location 

within 

borehole

Percentage of sample in each range of particle size (mm)

>9.5 4.75 to 

9.5

2.36 to 

4.75

1.18 to 

2.36

0.6 to 

1.18

0.3 to

0.6

0.15 to

0.3

0.075 to 

0.15

0.063 to 

0.075 <0.063

5/7 Upper 1.1 2.5 1.5 1.6 8.2 27.7 32.9 11.2 1.7 11.5

5/7 Middle 0.4 0.8 0.9 2.0 7.8 26.7 28.8 22.0 5.3 5.3

5/7 Lower 4.2 11.3 7.5 4.6 3.0 2.6 8.3 26.2 13.0 19.2

9 Upper 3.0 3.1 4.1 6.4 21.6 31.9 17.6 6.5 1.1 4.8

9 Lower 6.5 11.6 5.4 3.1 1.9 1.5 6.0 47.5 0.7 15.7

3/8 Upper 0.2 0.2 0.5 3.4 28.6 49.2 12.6 2.8 0.4 2.0

3/8 Middle 9.0 5.6 7.6 10.8 24.6 22.1 12.8 3.8 0.6 3.2

3/8 Lower 0.9 5.4 3.7 2.7 2.2 2.1 12.3 55.1 0.6 15.0

2 Upper 0.4 2.2 3.5 5.9 19.5 56.8 10.7 0.7 0.1 0.2

Site

Total 

weight of 

composite 

(g)

Amount 

processed 

(fraction of 

total)

Total length 

of cores 

composited

 (m)

Depth range below 

top of

 sediment

(m)

Core sections

5/7 21,932 1/4 8.83 0 to 10.05 5A-1H-1 through 5A-5H-1

5/7 22,152 1/4 10.59 11.14 to 23.91 7B-1H-2 through 7B-8H-1

5/7 9,876 1/4 6.2 24.15 to 30.82 7B-9H-1 through 7B-12H-1

9 23,708 1/4 11.5 0 to 16.08 9B-1H-1 through 9B-7H-2

9 12,280 1/4 6.51 16.78 to 23.51 9B-8H-1 through 9B-10H-1

3/8 9,680 1/4 3.93 0 to 4.92 3D-1H-1 through 3D-4E-1

3/8 16,992 1/4 6.56 6.16 to 14.08 8A-4H-1 through 8A-10H-1

3/8 10,140 1/4 7.2 14.53 to 22.51 8A-11H-1 through 8A-14H-1

2 2,576 1/2 1.46 0 to 1.46 2B-1H-1

82 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table C2. Particle-size distribution and gold tenor of heavy mineral concentrates, Englebright Lake, California, 2002.

[g, gram; mm, millimeter; mg, milligram; mg/m3, milligram per cubic meter; <, less than]

Site

Location 

within 

borehole

Heavy

mineral 

concentrate, 

total weight 

(g)

Percentage of sample in each range of particle size (mm)

Number of 

gold grains 

observed

Estimated 

gold 

weight 

(mg)

Gold 

tenor 

(mg/m3) 1.0 to

2.0

0.5 to

1.0

0.25 to 

0.50

0.063 to 

0.25 < 0.063

5/7 Upper 55.2 0.0 0.2 0.9 96.2 2.4 25 22.2 680

5/7 Middle 73.8 0.0 0.1 0.3 97.3 1.9 15 8.3 270

5/7 Lower 3.8 0.0. 2.6 2.6 92.1 2.6 5 6.9 310

9 Upper 107.3 0.1 0.1 6.8 91.9 0.9 8 2.2 92

9 Lower 2.3 0.0 0.0 4.3 91.3 4.3 15 2.1 58

3/8 Upper 49.8 0.4 0.4 14.3 84.7 0.2 8 0.5 38

3/8 Middle 73.9 0.1 1.5 13.8 84.0 0.1 6 1.1 44

3/8 Lower 2.3 0.0 0.0 4.3 91.3 4.3 10 1.7 84

2 Upper 49.3 1.0 0.6 54.8 43.6 0 15 4.3 840

median 92

Appendixes 83
Table C3. Mineralogical data from magnetic separation and optical microscopy for heavy mineral concentrates, Englebright Lake, 

California, 2002.

[Observations: —, not observed; x, trace; xx, abundant; xxx, very abundant; C, coarse; F, fine; VF, very fine; rst, rust stained; UF, ultra fine. mg, milligram; 

mm, millimeter; g, gram. In last column, light minerals include zircon and feldspar; dark include ilmenite, chromite, hornblende, and diopside]

Site

Location 

within 

borehole

Gold 

description

Amalgam 

(goldmercury) 

Iron 

ferricrete 

nodules

Pyrite Magnetite Miscellaneous

Total 

heavy 

minerals 

(g)

Strongly 

magnetic 

(magnetite) 

(g)

5/7 Upper C-F-VF xxx xxx xx xx — 55.2 31.4

5/7 Middle C-F-VF, rst x — — xx — 73.8 45.4

5/7 Lower C-F-VF, rst — — — xx — 3.8 1.6

9 Upper F-VF — — — xx — 107.3 39.8

9 Lower C-VF — — — xx — 2.3 0.8

3/8 Upper F-VF, rst x x – xx — 49.8 24.7

3/8 Middle F-VF — — — xx 1965 25 ¢ 

piece

73.9 20.9

3/8 Lower C-F-UF — — — xx — 2.3 1.3

2 Upper C-VF, rst — x — xx — 49.3 4

Site

Weakly 

magnetic 

(ferromagnesian 

minerals) 

(g)

Non-magnetic 

(light/dark 

minerals) 

(g)

Total 

magnetic 

fraction 

(weight

percent)

Total nonmagnetic 

fraction 

(weight 

percent)

Nonmagnetic 

fraction: 

Relative 

percent of 

light/dark 

minerals 

Light Dark

5/7 4.2 19.6 65 35 20 80

5/7 8.5 20 73 27 15 85

5/7 0.6 1.6 58 42 60 40

9 3.8 63.7 41 59 60 40

9 0 1.5 35 65 50 50

3/8 2.8 22.3 55 45 80 20

3/8 6.1 46.9 37 63 90 10

3/8 0 1 57 43 60 40

2 1.1 44.2 10 90 95 5

84 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Table C4. Summary of textural observations by scanning electron microscope on gold and amalgam in heavy mineral concentrates, Englebright Lake, California, 2002.

[Textures:1, primary/hydrothermal; 2, secondary/placer; 3, tertiary/amalgamation; 4, quaternary/post-amalgamation or sample-processing artifact. Observations: x, trace; xx, abundant; xxx, very abundant; —, not observed. Fe, iron; Zr, zirconium; O, oxygen; H, hydrogen; S, sulfur. BSE, backscatter electron; SE, secondary electron; SEM, scanning electron microscope]

Site

Location 

within 

borehole

SEM 

sample ID 

(ENG-)

Gold (Au)

 Mercury 

(Hg)

Amalgam (AuHg)

Zircon 

(ZrSiO4)

Iron oxides 

[Fe O2 3, 

FeO(OH), 

Fe(OH)3]

Iron 

sulfide 

(FeS2)

Other 

minerals

Figure 

number for 

photograph

Image 

type

Texture Texture or morphology

5/7 Upper 5A 3,4 pitted nugget xxx abraded aggregate mass — x x — D1 BSE5/7 Upper 5A4 2,3 Fe-stained nugget xx adsorbed Hg near hydrous 

Fe-oxide

— xx (hematite) x — D2A BSE

5/7 Upper 5A5 2,3 Fe-stained nugget xx adsorbed Hg near hydrous 

Fe-oxide

— xx (hematite) x — D2B SE

5/7 Upper 5A7 2,3 pitted nugget xx cracking where Hg abundant — x x — D3 BSE5/7 Upper 5AC1 2 pyrite-coated 

nugget

— — — x xxx — D4 BSE

5/7 Upper 5AC2 2 Fe stained and 

unstained nuggets

— — — xxx x — D5 BSE

5/7 Middle 7B1 3 pitted nugget xxx extensive pitting — — — — D6 BSE5/7 Middle 7B1a 3 Hg-saturated 

nugget

xxx extensive cracking — — — — D7 BSE

9 Upper 9B 1,2,3,4 crystalline nugget xxx abraded platelets — — — quartz D8 BSE9 Lower 9Bmacro 3,4 pitted nugget xxx crystalline aggregate — x — — D9A BSE9 Lower 9Bmicro 4 pitted nugget xxx single crystal — x — — D9B BSE9 Lower 9B8macro 2 nugget — — — x — — D10A BSE9 Lower 9B8micro 2 nugget — — — x — — D10B BSE3/8 Upper 3B1 1,2 pitted nugget xx — xx x — — D11 BSE3/8 Upper 3B3 2,3 nugget xx Hg beads — – — — D12 BSE3/8 Upper 3B4 3,4 pitted nugget xxx abraded aggregate mass — x — — D13 BSE3/8 Upper 3B5 3,4 pitted nugget xxx cracked amalgam platelet — x — — D14 BSE3/8 Middle 8A1 1,2 crystalline nugget — — — — — — D15 BSE2 Upper 2B1 2 Fe-stained nugget — — — xxx — — D16 BSE

Appendixes 85
Appendix D. Scanning Electron Microscope Photomicrographs Showing Gold and Amalgam 

Textures from the Heavy Mineral Concentrates from Englebright Lake, California 2002

Figure D1. Amalgam grain showing abrasion from processing (sample 5A).

86 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Figure D2. Two scanned electron microscope images of pseudo-hexagonal hematite platelets surrounded by 

mercury-rich halo, (A) Backscatter, (B) Secondary electron.

Appendixes 87
Figure D3. Gold grain with iron oxide (sample 5A7).

Figure D4. Gold grain with abundant diagenetic pyrite crystals (sample 5AC1).

88 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Figure D5. Iron-oxide coated gold nugget (on left) and clean gold nugget (on right) (sample 5AC2).

Figure D6. High magnification of pitted surface of gold nugget (sample 7B1).

Appendixes 89
Figure D7. Extensive cracking of amalgam in mercury-saturated gold nugget (sample 7B1).

Figure D8. Close-up view of nugget showing abrasion of amalgam in cavity with euhedral quartz crystal (sample 9B).

90 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Figure D9. Amalgam grains (sample 9B) (A) Aggregate containing amalgam crystal in upper right, and 

(B) Close-up view of the amalgam crystal, dimensions 6 x 8 micrometers.

Area of 

figure 10B

A

B

Appendixes 91
Figure D10. Placer gold grain of high purity, no visible mercury (sample 9B8) (A) View of entire grain, (B) Close-up 

view showing smooth texture of gold.

Area of 

figure 10B

A

B

92 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Figure D11. Large, pitted gold grain with 100-micrometer, euhedral zircon crystal (sample 3B1).

Figure D12. Grain of gold containing small beads of elemental mercury (sample 3B3).

Appendixes 93
Figure D13. Grain of amalgam showing smearing from processing (sample 3B4).

Figure D14. Grain of amalgam showing fracture (sample 3B5).

94 Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments, Englebright Lake, California, 2002
Figure D15. Octahedral crystal forms of gold in vug of nugget (sample 8A1).

Figure D16. Iron-stained gold nugget with no trace of mercury (sample 2B1).

Appendixes 95
Alpers and others—Geochemical Data for Mercury, Methylmercury, and Other Constituents in Sediments from Englebright Lake, California, 2002

—Data Series 151

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