Evaluating Chukchi Sea Trace Metals and Hydrocarbons 

in the Yukon River Delta, Alaska

Principal Investigator

Paul McCarthy1,2

Graduate Student 

John Perreault1

1

Department of Geosciences, University of Alaska Fairbanks

2

Geophysical Institute, University of Alaska Fairbanks

FINAL REPORT 

December 2016

OCS Study BOEM 2016-078
Contact Information: 

email: CMI@alaska.edu

phone: 907.474.6782 

fax: 907.474.7204

Coastal Marine Institute

College of Fisheries and Ocean Sciences

University of Alaska Fairbanks

P. O. Box 757220 

Fairbanks, AK 99775-7220 

This study was funded in part by the U.S. Department of the Interior, Bureau of Ocean Energy Management (BOEM) through 

Cooperative Agreement M12AC00001 between BOEM, Alaska Outer Continental Shelf Region, and the University of Alaska 

Fairbanks. This report, OCS Study BOEM 2016-078, is available through the Coastal Marine Institute, select federal 

depository libraries and can be accessed electronically at http://www.boem.gov/Alaska-Scientific-Publications.

The views and conclusions contained in this document are those of the authors and should not be interpreted as representing 

the opinions or policies of the U.S. Government. Mention of trade names or commercial products does not constitute their 

endorsement by the U.S. Government.
ii

TABLE OF CONTENTS

LIST OF FIGURES ....................................................................................................................... iii

LIST OF TABLES......................................................................................................................... iii

LIST OF APPENDICES FIGURES AND TABLES .................................................................... iii

ABSTRACT................................................................................................................................... iv

INTRODUCTION. ..........................................................................................................................1

METHODS ..................................................................................................................................... 2

Field Methods ..................................................................................................................................2

Analytical Methods..........................................................................................................................3

PAH analyses....................................................................................................................3

Trace metal analyses ........................................................................................................3

Radioisotope analyses ......................................................................................................4

RESULTS AND DISCUSSION......................................................................................................4

Organic Compounds.....................................................................................................................4

Trace Metals.................................................................................................................................5

Water samples...................................................................................................................5

Bedload .............................................................................................................................8

Radioisotopes and Radiocarbon Dating .......................................................................................9

SUMMARY...................................................................................................................................12

REFERENCES ..............................................................................................................................13

APPENDICES ...............................................................................................................................15
iii

LIST OF FIGURES

Figure 1: Map of study area .............................................................................................................2

Figure 2: Cores taken from the Yukon River delta........................................................................10

Figure 3: Cesium-137 activity per mass unit at core depths in centimeters ..................................11

LIST OF TABLES

Table 1: PAH targets........................................................................................................................3

Table 2: Trace metal targets.............................................................................................................4

Table 3: Selected trace metal data from Yukon River water samples at Pilot Station, Alaska .......5

Table 4: Selected trace metal data from Yukon River water samples at Pitka Point and Mountain 

Village, Alaska.................................................................................................................................6

Table 5: Selected trace metal data from Yukon River water samples at Arolokovik and Fish 

Village, Alaska.................................................................................................................................7

Table 6: Yukon River discharge at Pilot Station, Alaska. ...............................................................7

Table 7: Selected trace metal data from Yukon River bedload sediment samples..........................8

LIST OF APPENDICES FIGURES AND TABLES

Figure A1: Organic compounds identified in the Arolokovik suspended water sample ...............15

Table A1: Sampling site coordinates.............................................................................................15

Table A2: PAH targets and results of standards............................................................................16

Table A3: PAH targets and results of core samples ......................................................................19

Table A4: Physical description of core samples............................................................................22

Table A5: Core sample radioisotope curve data values.................................................................23

.
iv

ABSTRACT

Yukon River sediments may comprise the majority of the deposits currently present in 

the Chukchi Sea. Currently, one-third of the Yukon River’s sediment load may be carried to the 

Chukchi Sea, and it is estimated that as much as 81% of Yukon sediments reached the Chukchi 

Sea during the Holocene period (Nelson and Creager, 1977). This suggests that the majority of 

sediment present in the Chukchi Sea is derived from the Yukon River. This work focused on 

evaluating the trace metal concentrations and polycyclic aromatic hydrocarbons (PAHs) of the 

Yukon Basin, the largest contributor to the overall sediment budget of the eastern Chukchi Sea. 

This project provided a snapshot of trace metal and PAH concentrations in the Yukon 

River water and active bedload. Seventeen PAH targets were sought in bed load sediments, water 

samples with suspended and dissolved material, and cores up to three meters in depth. No PAH 

targets were detected at a concentration above 4 ppb. The project also provided the first trace 

metal values published for the study area and provided historical radioisotope data from core

samples. The data presented in this report reflect the current state of a non-tidally influenced 

stretch of the lower Yukon River and can be used as baselines to inform future work. 
INTRODUCTION

Metals and hydrocarbons from offshore drilling operations can alter the natural 

biogeochemical state of marine ecosystems (Neff et al., 1987; Neff, 2005; Trefry et al., 2014). 

Previous studies have added to knowledge of concentrations of metals and hydrocarbon 

pollutants near oil lease areas (e.g., Brown et al., 2004; Brown, 2010; Naidu et al., 2011; Trefry 

et al., 2012; Trefry et al., 2014). However, some ambient levels of metals and hydrocarbons in 

Arctic marine sediments and seawater are thought to be derived from terrestrial sources (Brown, 

2010; Trefry et al., 2012). The work reported here complements pollutant studies by examining 

terrestrial inputs to the Chukchi Sea from upstream sources in the Yukon River. 

Yukon River sediments may constitute the majority of the deposits present in the 

Chukchi Sea. It is estimated that one-third of the Yukon River's sediment load may be carried to 

the Chukchi Sea and that as much as 81% of Yukon sediments reached the Chukchi Sea during 

the Holocene (Nelson and Creager, 1977). This suggests that the majority of Chukchi Sea 

sediment is derived from the Yukon River. Evaluating the trace metal and hydrocarbon 

concentrations of the Yukon River system, and the temporal trends in fluctuations of these 

constituents to the Chukchi Sea, will contribute important baseline data for the Chukchi Sea

region. This work focuses on evaluating the trace metal concentrations and polycyclic aromatic 

hydrocarbons (PAHs) of the Yukon basin, the largest contributor to the overall sediment budget 

of the eastern Chukchi Sea. Identifying upstream sources is important because the Yukon River 

naturally erodes substantial natural hydrocarbon sources such as coal beds in the Tanana 

tributary and carries trace metals from many Alaska Range, Brooks Range, and Tanana upland 

rocks and ore bodies (Beikman, 1980; Dornblaser and Halm, 2006). The Yukon Basin may also 

collect PAHs from coal and oil processing, PAHs from wild fires in the Alaska Interior, and

metal contaminants introduced from two of Alaska’s largest ore mining operations (Fort Knox 

and Pogo gold mines). These sources may substantially contribute to sediment concentrations 

apparent in the Chukchi Sea. 

A variety of meteorological mechanisms may impact the temporal delivery of metals and 

hydrocarbons from the Yukon Basin. The Yukon River has been shown to be responsive to, and 

operate in-phase with, the Pacific Decadal Oscillation (PDO; Brabets and Walvoord, 2009), a 

natural climate cycle similar to the El Nino Southern Oscillation (Mantua et al., 1997; Mantua, 

2001). The PDO affects marine ecosystems around Alaska (Francis and Hare, 1994) and could 

have considerable influence on riverine fluxes to the Chukchi Sea, including metals and 

hydrocarbons. Yukon River discharge has been trending to earlier onset at higher rates, 

(Dornblaser and Streigl, 2007; Streigl et al., 2007) and wild fires in Alaska have increased as a 

result (Westerling et al., 2006). Increased runoff delivers more sediment and associated trace 

metals and hydrocarbons to the Chukchi Sea. Increased fire activity leads to higher hydrocarbon 

concentrations in runoff because there is less vegetation to hold down sediment. Loss of

vegetative cover also leads to higher erosion rates, which promote increased release of metals 

from rocks and soil (Swanson, 1981). 

1
The purpose of this project was to develop an inventory of trace metals and PAHs 

derived from the Yukon Basin and delivered to the Chukchi Sea. We also explored whether 

sediment cores taken from high-sedimentation-rate Yukon delta deposits provide a complete 

historic record (~150 years) of metal and hydrocarbon delivery to the Chukchi Sea and whether 

trace metal concentrations in Yukon River sediments are significantly different in sand, silt, and 

clay-sized particles.

METHODS

Field Methods

Active river channel bedload and suspended-load sediments were collected from the 

Yukon River at five points for trace metal and PAH analyses (Figure 1). Bedload samples were 

collected from riverbanks or midstream sandbars. Suspended-load samples were collected from 

water pumped at 1 m below the river surface. Water samples were subsequently filtered in the 

field for trace metal analysis and frozen to be filtered in the laboratory for PAH samples.

Suspended-load and water samples were collected in the summers of 2012 and 2013 and in early 

spring of 2013 before break-up. 

Figure 1: Map of study area. Location of core samples (red dots) and suspended sediment and water 

samples (blue dots) along the Yukon River delta. (Geographic coordinates: appendix Table A1)

2
Sediment cores were extracted from three permafrost-free locations selected in the active 

delta lobe of the river (Figure 1) using a percussion corer. Cores were taken from the active 

channel (Site 1–YD1) and from abandoned channels upstream (Site 2–YUK1 and Site 3–Y1). 

Core samples were 1–3 m long and non-continuous. 

Analytical Methods

PAH analyses 

Dry core samples were taken at the Woods Hole Oceanographic Institute. Suspended 

sediment samples were frozen in 1 L Teflon bottles until analysis. The entire volume of water 

and sediment samples were evaporated at 40o

C and the bottle rinsed with dichloromethane.

Bedload samples were also frozen until analysis and then evaporated at 40o

C until dry. All dry 

samples were then spiked with a 1.56 ppm d8 Naphthalene standard and soaked in 25 mL of 

dichloromethane. The resulting mixtures of sediment, standard, and solvent were placed in a 

sonication bath for 30 minutes, centrifuged at 4500 rpm for 15 minutes and subsampled as 1 mL 

aliquots for analysis. Spiked samples were run to demonstrate extraction efficiency (see 

Appendix Table A2).

Suspended-load and bedload sediment samples were analyzed for PAH concentrations at 

the Water and Environmental Research Center (WERC, University of Alaska Fairbanks) 

laboratory using an Agilent 6890N Gas Chromatograph machine following EPA Method 8270 

for semi-volatile organics; 35o C (hold 4 minutes), to 245o C @ 7o C/minute.

PAH compounds were measured using a gas chromatograph in selective ion mode (SIM).

Compounds were selected to match those targeted in the Chukchi Sea Offshore Monitoring in the 

Drilling Area (COMIDA) Chemistry and Benthos Study (CAB) (Dunton et al., 2012). These 

compounds (Table 1) were selected because they represent high-temperature combustion PAHs, 

key representatives of PAHs often attributed to oil (natural or contaminant), and PAHs known to

have a natural origin. 

Table 1: PAH targets. (*found in COMIDA-CAB study) 

Naphthalene* Acenapthylene Acenapthene 

Fluorene Phenanthrene* Anthracene

Fluoranthene* Pyrene* Retene*

Benz(a)anthracene* Chrysene Benzo(b)fluoranthene

Benzo(k)fluoranthene Benzo(a)pyrene* Indeno(1,2,3-c,d)pyrene

Dibenz(a,h+ac)anthracene Benzo(g,h,i)perylene* 

Trace metal analyses

Trace metal analyses for water samples were performed on an Agilent 7500ce ICP-MS at 

the University of Alaska Fairbanks Advanced Instrumentation Laboratory (AIL). RF power was 

set to 1500 W. The instrument was tuned upon startup to optimize the sensitivity at masses 7, 89, 

3
and 205. Oxides (156/140) were tuned to less than 2% and doubly charged ions (70/140) were 

tuned to less than 3%. Li7, Be9, Fe 56, and Fe57 were analyzed in H2 mode; Mg 24, V51, Cr52, 

Ni60, Cu63, and As75 were analyzed in Helium mode; and Al27, Ca43, Ca44, Cr53, Mn55, 

Co59, Zn66, Sr88, Ag107, Cd111, Sb121, Ba137, Hg202, Tl205, Pb208, and U238 were 

analyzed in no gas mode. Internal standards were Sc45, Ge72, and Te125. Calibration standards 

were made from single element standards (Ultra Scientific) ranging from 0.1–50 ppb for all 

elements except for Mg, Ca, Fe, and Sr which were calibrated from 1–500 ppb, and Hg202 

which was calibrated from 0.01–5 ppb. Continuing calibration verifications (CCVs) and 

continuing calibration blanks (CCBs) were analyzed every 10 samples. NIST 1640 was analyzed 

as a secondary standard. Trace metal targets were selected to match the 2002–2003 USGS 

Yukon River study targets (Table 2), providing a continued, overlapping record downriver from 

Pilot Station, the furthest downriver site sampled by USGS. 

Table 2: Trace metal targets. Targets complement the USGS Yukon River study, 2002–2003. 

Barium (Ba) Chromium (Cr) Lithium (Li) Lead (Pb) Thallium (Tl)

Cadmium (Cd) Cesium (Cs) Manganese (Mn) Rubidium (Rb) Uranium (U)

Cerium (Ce) Copper (Cu) Molybdenum (Mo) Rhenium (Re) Vanadium (V)

Cobalt (Co) Iron (Fe) Nickel (Ni) Strontium (Sr) Zinc (Zn)

Bedload samples for trace metal analysis were collected in the field using clean plastic bags. 

Samples were gathered from the river bank or sandbar at the locations shown in Figure 1. 

Portions of the gathered sample were dried at 50o

C for up to 24 hours, depending on water 

content in the sample, and then ground and mixed with a polyvinyl alcohol binder. The sample 

was then pressed into a pellet at 20,000 psi and analyzed using a PANalytical Axios four 

kilowatt wavelength dispersive X-ray fluorescence spectrometer (XRF). Calibration standards 

used were SO-4 (*) and GXR-4 (*), following Barker et al., 2014 and Ilgen et al., 2011. 

Radioisotope analyses 

Radiocarbon dates, and 210Pb, 214Pb, and 137Cs radioisotopes were determined at 

Woods Hole Oceanographic Institute. 

RESULTS AND DISCUSSION

Organic Compounds

Of the 17 PAH targets sought in this survey, none were detected in any water, core, or 

bedload samples above the established base detection limit of 4–8 ppb (See Appendix Figure A1, 

Appendix Table A3 ) Future work that concentrates the remaining sample portions may be able 

to improve the lower detection limit and find smaller concentrations if they are present. 

4
Trace metals

Water samples 

Tables 3–5 show trace metal data, and selected major elements, from Yukon River water 

samples. Three locations, Pilot Station, Pitka’s Point, and Fish Village, were sampled during 

both summer 2012 and summer 2013. In general, values for trace metals in water samples were 

higher in summer 2013 than in summer 2012, except for Strontium at all locations, Uranium at 

Pitka's Point and Fish Village, and Mercury at Fish Village, which were all lower.

Four stations were sampled during July 2012 (Pilot Station, Pitka’s Point, Arolokovik, 

and Fish Village). No general trends in trace metal concentrations are detected in Yukon River 

water moving downstream. Mercury levels at Fish Village were higher than at the other stations; 

the reasons for this are unclear.

Samples taken from Pilot Station during March and June 2013 were analyzed.

Concentrations of trace metals were generally higher in June than in March, except for Strontium

and Uranium. Samples were also taken in March 2013 at Mountain Village, downstream from 

Pilot Station. Comparison of these two stations during March 2013 shows an increase in all trace 

metal concentrations downstream, in marked contrast to the variable downstream concentrations 

during summer 2012 and 2013. 

Table 3: Selected trace metal data from Yukon River water samples at Pilot Station, Alaska. Values that 

were below lower level of detection (LLD) are shown as (-). 

PILOT STATION

PILOT STATION 

BANK PILOT STATION PILOT STATION

7/21/2012 7/22/2012 3/11/2013 6/13/2013

ppb %rsd ppb %rsd ppb %rsd ppb %rsd

Beryllium 0.08 3.51 0.08 1.75 0.07 0.58 0.09 2.54

Magnesium 7587.00 1.97 6357.00 0.41 10270.00 2.30 4728.00 0.62

Aluminum 44.89 2.92 60.79 2.15 0.69 5.45 318.20 1.78

Calcium 20690.00 0.36 20400.00 0.75 22700.00 1.50 18150.00 0.87

Vanadium 0.92 1.21 0.90 1.96 0.30 0.72 2.01 1.45

Chromium 0.44 1.05 0.49 1.01 0.28 0.48 1.01 0.74

Manganese 5.62 0.75 12.23 0.37 48.58 1.47 62.85 1.12

Iron 129.00 0.37 213.50 1.90 70.26 0.27 832.90 0.38

Cobalt 0.48 0.22 0.50 0.23 0.48 0.34 0.85 0.65

Nickel 1.00 0.53 1.10 0.68 0.92 1.19 2.57 1.56

Copper 2.61 0.93 2.33 0.80 0.60 0.86 4.93 0.74

Arsenic 1.07 1.84 1.05 3.31 0.50 4.81 1.60 1.83

Strontium 143.20 0.27 147.50 0.85 180.70 2.58 107.30 0.22

Silver 0.21 0.26 0.21 0.07 0.21 0.30 0.22 0.34

Antimony 0.07 6.67 0.05 9.79 - 3.60 0.24 2.82

Barium 50.33 1.08 55.76 1.66 62.39 0.44 66.05 1.07

Mercury 0.01 29.56 0.01 16.63 0.00 64.61 0.03 10.52

Uranium 0.40 19.68 0.74 0.69 0.76 2.08 0.17 14.31

5
Table 4: Selected trace metal data from Yukon River water samples at Pitka Point and Mountain Village, 

Alaska. Values that were below lower level of detection (LLD) are shown as (-).

PITKA'S POINT PITKA'S POINT

MOUNTAIN 

VILLAGE

7/20/2012 6/13/2013 3/13/2013

ppb %rsd ppb %rsd ppb %rsd

Beryllium 0.08 0.99 0.10 4.37 0.08 1.48

Magnesium 7725.00 0.99 4734.00 1.82 10390.00 1.08

Aluminum 20.37 0.78 613.10 1.54 8.00 2.10

Calcium 19990.00 0.22 18030.00 1.37 27330.00 0.36

Vanadium 0.89 0.71 2.81 0.54 0.39 0.90

Chromium 0.36 0.25 1.69 2.37 0.33 1.09

Manganese 2.95 1.15 64.23 0.91 66.90 0.44

Iron 72.06 1.46 1520.00 2.76 357.60 1.27

Cobalt 0.45 0.62 1.11 0.45 0.51 0.37

Nickel 0.99 1.40 3.27 0.27 1.04 0.73

Copper 2.50 0.94 5.75 1.04 0.72 0.93

Arsenic 1.04 4.60 1.79 3.12 0.70 5.90

Strontium 143.10 2.15 111.50 0.72 212.40 1.94

Silver 0.21 0.01 0.22 0.55 0.21 0.29

Antimony 0.08 7.63 0.28 0.73 - 1.47

Barium 51.49 2.09 62.76 0.29 78.97 3.78

Mercury 0.01 3.72 0.02 2.00 0.01 7.80

Uranium 0.84 1.43 0.12 31.64 0.86 0.23

6
Table 5: Selected trace metal data from Yukon River water samples at Arolokovik and Fish Village, 

Alaska.

Mean discharge for the Yukon River at Pilot Station is given in Table 6 for the dates the 

water samples were taken. Higher trace metal concentrations in summer 2013 than in summer 

2012 can be attributed to higher discharge in the river. Higher discharges in summer than in 

March probably also account for the generally higher concentrations of trace metals in summer. 

Some of the variation in metal concentrations at different stations during summer 2012 may also 

be related to discharge variations.

Table 6: Yukon River discharge at Pilot Station, Alaska. 

(source: http://waterdata.usgs.gov/)

Date Discharge (cubic 

ft./second)

7/20/2012 518,000

7/21/2012 515,000

7/22/2012 511,000

3/11/2013 51,000

6/13/2013 71,000

AROLOKOVIK FISH VILLAGE FISH VILLAGE

7/21/2012 7/21/2012 6/13/2013

ppb %rsd ppb %rsd ppb %rsd

Beryllium 0.08 1.05 0.08 1.85 0.11 1.55

Magnesium 4153.00 1.32 8334.00 0.77 4887.00 0.45

Aluminum 19.18 4.15 122.20 2.48 1061.00 0.58

Calcium 16600.00 0.13 22020.00 0.15 18860.00 0.34

Vanadium 1.34 1.11 1.12 0.08 4.61 0.94

Chromium 0.32 0.93 0.97 0.29 2.91 0.96

Manganese 20.83 2.78 7.11 1.20 113.90 0.52

Iron 80.88 1.36 215.40 3.32 2731.00 0.70

Cobalt 0.50 1.30 0.54 0.73 1.62 0.39

Nickel 0.70 1.56 1.54 0.50 4.48 1.29

Copper 1.51 1.16 2.95 0.64 7.03 1.40

Arsenic 0.82 4.56 1.16 1.63 2.39 2.35

Strontium 117.00 1.45 143.50 0.88 122.50 0.34

Silver 0.21 0.33 0.21 0.14 0.23 0.31

Antimony 0.08 8.21 0.10 2.77 0.35 1.58

Barium 45.80 7.10 55.93 4.82 78.50 1.16

Mercury 0.01 65.73 0.06 25.56 0.02 9.12

Uranium 0.34 55.12 0.67 32.01 0.13 15.84

7
Rember and Trefry (2004) suggested that dissolved trace metal concentrations are 

strongly influenced by the discharge of soil interstitial water and shallow surface water that is 

flushed into arctic rivers during spring snowmelt. They further suggested that pools of standing 

water and lakes store leached trace metals from surrounding soils that are released during the 

spring thaw. It seems likely that a similar mechanism would also be active in the Yukon River 

watershed during heavy rains in summer as the permafrost continues to thaw. Other variations in 

dissolved trace metal concentrations from station-to-station may also result from differences in 

regional lithology and pH (Rember and Trefry, 2004) or from recent fire activity, which would 

increase sediment runoff and release of metals from rocks and soil (Swanson, 1981). 

Bedload samples 

Table 7: Selected trace metal data from Yukon River bedload sediment samples. Values that are below 

lower level of detection (LLD) are shown as (-), error is reported in counting standard error (CSE).

Sample 

name

Ba 

(ppm)

Cd 

(ppm)

Ce 

(ppm)

Co 

(ppm)

Cr 

(ppm)

Cs 

(ppm)

Cu 

(ppm)

Mn 

(ppm)

Arolokovik 

Bar

072112

Concentration 549.165 - 19.938 - 128.241 - - 456.897

LLD (ppm) Not calc. 3.971 15.018 Not calc. 2.247 5.441 0.899 3.860

CSE 2.911 1.241 3.284 0.417 1.176 1.974 0.391 2.672

Arolokovik 

Bank

072112

Concentration 570.370 - 22.616 - 79.323 - - 448.292

LLD (ppm) Not calc. 3.966 14.144 Not calc. 2.098 5.111 0.868 3.615

CSE 2.778 1.236 3.101 0.399 1.020 1.840 0.372 2.550

Mountain 

Village Bank 

072112

Concentration 569.277 - - 0.168 64.426 - - 244.424

LLD (ppm) Not calc. 3.750 13.713 Not calc. 2.020 4.919 0.816 3.541

CSE 2.736 1.172 2.954 0.357 0.963 1.772 0.344 2.039

Mountain 

Village Bank 

092813

Concentration 498.636 - - - 67.866 - - 299.026

LLD (ppm) Not calc. 3.811 13.997 Not calc. 2.054 5.040 0.835 3.656

CSE 2.642 1.193 3.009 0.375 0.984 1.816 0.353 2.217

Pilot Station 

South Bank 

072112

Concentration 727.770 - 19.634 - 88.644 - 16.139 536.840

LLD (ppm) Not calc. 3.673 14.119 Not calc. 2.099 5.171 0.866 3.671

CSE 3.052 1.151 3.082 0.409 1.033 1.876 0.412 2.726

Pilot Station 

North Bank 

072212

Concentration 826.614 - 25.376 - 101.592 - 10.844 642.546

LLD (ppm) Not calc. 4.091 14.712 Not calc. 2.206 5.362 0.909 3.795

CSE 3.293 1.280 3.221 0.436 1.100 1.951 0.420 2.996

Pilot Station 

South Bank 

092713

Concentration 579.328 - - 0.864 100.168 - - 309.470

LLD (ppm) Not calc. 3.811 14.174 Not calc. 2.093 5.156 0.848 3.679

CSE 2.834 1.191 3.091 0.384 1.065 1.859 0.364 2.252

Pitka's Point 

Bar 

092813

Concentration 494.332 - 24.603 - 153.279 - - 613.825

LLD (ppm) Not calc. 4.352 15.688 Not calc. 2.340 5.603 0.955 4.048

CSE 2.938 1.358 3.442 0.454 1.261 2.052 0.408 3.087

Pitka's Point 

Bar 

072112

Concentration 530.0253 - 19.781 - 150.646 - - 470.828

LLD (ppm) Not calc. 3.947 14.897 Not calc. 2.232 5.383 0.897 3.865

CSE 2.864 1.235 3.254 0.417 1.213 1.956 0.382 2.703

 

8
Table 7: Continued. 

Sample 

name

Mo 

(ppm)

Ni 

(ppm)

Pb 

(ppm)

Rb 

(ppm)

Sr 

(ppm)

Tl 

(ppm)

U 

(ppm)

V

(ppm)

Zn

(ppm)

Arolokovik 

Bar

072112

Concentration 2.242 21.184 8.020 41.671 254.166 - 4.078 82.441 71.089

LLD (ppm) 0.492 0.937 1.883 0.599 0.442 2.069 1.434 3.685 0.896

CSE 0.168 0.443 0.652 0.202 0.335 0.780 0.566 1.079 0.384

Arolokovik 

Bank

072112

Concentration 2.166 14.926 8.602 47.288 216.861 - 4.330 65.308 58.151

LLD (ppm) 0.475 0.910 1.794 0.583 0.428 1.965 1.376 3.052 0.867

CSE 0.163 0.399 0.623 0.203 0.307 0.745 0.544 0.946 0.361

Mountain 

Village 

Bank 

072112

Concentration 1.808 15.265 8.598 49.441 216.940 - 2.109 54.914 48.380

LLD (ppm) 0.454 0.795 1.721 0.558 0.411 1.876 1.329 2.845 0.824

CSE 0.156 0.366 0.597 0.197 0.296 0.711 0.522 0.893 0.336

Mountain 

Village 

Bank 

092813

Concentration 1.356 18.711 8.639 40.316 249.260 - 3.102 60.465 52.025

LLD (ppm) 0.459 0.844 1.756 0.566 0.418 1.921 1.346 2.921 0.844

CSE 0.158 0.400 0.610 0.191 0.317 0.728 0.531 0.921 0.347

Pilot Station 

South Bank 

072112

Concentration 1.893 28.972 15.760 69.475 233.560 2.372 6.163 86.629 104.957

LLD (ppm) 0.470 0.935 1.724 0.567 0.420 1.863 1.345 3.267 0.859

CSE 0.161 0.476 0.618 0.222 0.315 0.710 0.537 1.011 0.400

Pilot Station 

North Bank 

072212

Concentration 2.221 29.901 15.223 84.710 231.808 1.786 4.109 96.330 125.694

LLD (ppm) 0.488 0.987 1.872 0.602 0.444 2.043 1.443 3.530 0.901

CSE 0.168 0.500 0.667 0.245 0.325 0.778 0.570 1.087 0.433

Pilot Station 

South Bank 

092713

Concentration 2.345 18.493 8.257 51.420 238.668 - 3.458 62.114 58.321

LLD (ppm) 0.468 0.865 1.752 0.573 0.422 1.905 1.355 3.214 0.846

CSE 0.161 0.405 0.607 0.204 0.314 0.725 0.535 0.960 0.354

Pitka's 

Point Bar 

092813

Concentration 3.366 27.363 8.898 35.673 268.152 - 4.619 102.042 74.981

LLD (ppm) 0.510 1.038 1.975 0.630 0.465 2.170 1.504 4.140 0.949

CSE 0.176 0.507 0.686 0.205 0.355 0.824 0.596 1.197 0.407

Pitka's 

Point Bar 

072112

Concentration 2.776333 21.89067 8.913333 42.05533 236.369 - 3.589667 83.57667 62.253

LLD (ppm) 0.486667 0.935333 1.839333 0.594 0.439 2.002667 1.420667 3.688333 0.892

CSE 0.1672 0.445867 0.6382 0.2013 0.3236 0.7583 0.560567 1.083533 0.374133

Radioisotopes and Radiocarbon Dating

Three sediment cores up to 4.5 m long were sampled in the Yukon River delta. Core 

physical characteristics are found in Appendix Table A4. Cores were taken from the active 

channel (YD1) and from inactive channels further upstream that had previously filled with 

sediment (YUK1 and Y1). The upstream core (Y1) is the oldest with a basal radiocarbon age of 

10.3 ka, the intermediate core (YUK1) has a basal age of 0.5 ka, and the downstream core (YD1) 

has a modern basal age (younger than 1950) based on the presence of 137Cs throughout the core

(Figure 2). The upper parts of the cores, where 137Cs is present, were described and sampled for 

trace metal and PAH analyses and Pb radioisotope distribution. Corresponding 137Cs, 210Pb 

and 214Pb radioisotope curve data are shown in Appendix Table A5. 

9
Figure 2: Cores taken from the Yukon River delta. Radiocarbon ages are shown at the base of the cores. 

Core YD1 (Site 1) is the most downstream core and core Y1 (Site 3) is the most upstream core. Width of 

the core indicates the sediment type at that depth in general. Detailed descriptions of the upper parts of the 

cores, where 137Cs was present and from which PAH data were sampled, are in Table 10. 

Radiocarbon dates, and 210Pb, 214Pb, and 137Cs radioisotope data from this project will 

permit the future construction of a down-core chronology from Yukon delta sediment cores to 

resolve historical variability in trace metals and PAH abundance during deposition. 

The primary use of 137Cs as a dating tool is to locate peaks associated with the subaerial 

testing of nuclear weapons which led to an atmospheric dispersal of Cesium and other 

radioisotopes, particularly across the northern hemisphere. Nuclear testing began to appear in 

sediments in the western and central U.S. in the early 1950’s. If the appearance and peak can be 

identified, then a rate may be obtained for sedimentation using these points in the core. However, 

there are complications in a river system for this method over a lacustrine core. Sediment mixing 

can obscure the peak, channel movement may truncate the sedimentation at an unknown date 

after the initial appearance of 137Cs, and the channel return may remove the previous deposition, 

making the dating record shorter.

The best case scenario is to identify two peaks in 137Cs, which are generally identified at 

1957 and 1963 peak input years (Van Metre, et al, 2004), or to work from the start of occurrence 

to the peak value in 1964. We had mixed results identifying peaks in the cores (See Figure 3). 

Core YD1 displays two prominent peaks, but at very low concentrations. Core YUK1 shows one 

10
peak that may be the 1964 maximum atmospheric inventory of 137Cs. YUK1 is also an 

abandoned channel, so the date of the top of the sediment column when new sedimentation from 

the Yukon ceased is unknown but after 1964. The furthest upstream core, Y1, is mostly likely 

oldest. It was gathered from a low sandbar in an active channel and is modern. There is a 

prominent peak in 137Cs activity and a depth of only 10 cm, with a smaller peak at 45 cm, with 

two points of significant error in between, at 25 cm and 35 cm depth. This sample can clearly be 

stated to be modern, but the rate of sedimentation can only be poorly determined due to the 

likelihood of upstream sediment contributing to the near surface peak in this location when it 

was active. 

The reliability of age dating between cores can vary and is difficult to quantify. Using 

professional judgment, these cores were classified similar to Van Metre, et al, 2004. YD1 is rated 

“good” for clear 137Cs peaks and reliable data. Error size and less clearly identifiable peaks 

contributed to a “fair” rating for core YUK1, and “poor” for Y1, for reasons noted above. 

The sedimentation rate for core YD1 and Y1was determined as 12.8 cm/year for YD1 and 5.8

cm/year for Y1, respectively, using the equation: sedimentation rate = cumulative depth/time interval 

The sedimentation rate was determined as 0.79 cm/yr. for core YUK1, using 1952 (first 

appearance in the core of 137Cs) to a peak in 1964 as the time interval. 

Figure 3: Cesium-137 activity per mass unit at core depths in centimeters. Cores were taken from the 

active channel (Site 1– YD1) and from abandoned channels upstream (Site 2–YUK1 and Site 3– Y1). 

11
SUMMARY

This report provides a snapshot of the active water and bedload and allows for future 

construction of a historical data set through cored material of both a suite of trace metals and 

polycyclic aromatic hydrocarbons. The data presented here serves two purposes. It shows the 

current state of the last non-tidally influenced stretch of the Yukon River, and it helps to 

establish a baseline for comparison for future work that may lead to more conclusive studies as 

climate conditions in the Yukon River basin evolve and potentially alter the contributions of 

trace metals and hydrocarbons from the many tributaries and drainage areas.

Seventeen PAH targets were sought in bedload sediments, water samples with suspended 

and dissolved material, and cores up to three meters in depth. None were detected at a 

concentration above 4 ppb. Further work may increase detection of PAHs by concentrating 

remaining samples.

Trace metal values on this part of the Yukon River have not been previously published. 

In 2002–2003, the USGS sampled as far downriver as Pilot Station, which is the furthest upriver 

sampling station in this study. This study complements the USGS data to complete a full survey 

of the Yukon River trace metal content from Eagle, Alaska to the opening of the delta at the river 

mouth. Future work will also be able to look at the historical trace metal values and PAH values 

using the cores acquired here.

12
REFERENCES

Barker, A.J., Douglas, T.A., Jacobson, A.D., McClelland, J.W., Ilgen, A.G., Khosh, M.S., Lehn, 

G.O., and Trainor, T.P. 2014. Late season mobilization of trace metals in two small Alaskan 

arctic watersheds as a proxy for landscape scale permafrost active layer dynamics. Chemical 

Geology, 381, 180–193. 

Beikman, H.M. 1980. Geologic map of Alaska.1:250,000. U.S. Geological Survey Special Map. 

Brabets, T.P. and Walvoord, M.A., 2009. Trends in streamflow in the Yukon River basin from 

1944 to 2005 and the influence of the Pacific Decadal Oscillation, Journal of Hydrology, 

371, 108–119. 

Brown, J.S. 2010. cANIMIDA Task 2: Hydrocarbon and metal characterization of sediments in 

the cANIMIDA study area. Final Report, OCS Study MMS 2010-004, Mineral Management

Service, Anchorage, AK. 

Brown, J.S., Trefry, J.H., Cook, L.L., and Boehm, P.D. 2004. ANIMIDA Task 2: Hydrocarbon

and metal characterization of sediments, bivalves, and amphipods in the ANIMIDA study

area. Final Report, OCS Study MMS 2004-024, Minerals Management Service,

 Anchorage, AK. 

Dornblaser, M. and Halm, D.R. 2006. Water and sediment quality of the Yukon River and its

tributaries, from Eagle to St. Mary’s, Alaska. 2002–2003 U.S. Geological Survey, openfile report 2006-1228, 213 p. 

Dornblaser, M.M. and Striegl, R.G. 2007. Nutrient (N,P) loads and yields at multiple scales and 

sub-basin types in the Yukon River basin, Alaska. Journal of Geophysical Research: 

Biogeosciences, 112 (G4). 

Dunton, K.H., Cooper, L.W., Grebmeier, J.M., Harvey, H.R., Konar, B., Maidment, D., 

Schonberg, S.V., and Trefry, J. 2012. Chukchi Sea offshore monitoring in drilling area 

(COMIDA): Chemical and benthos (CAB). Final Report, OCS Study BOEM 2012-012, 

Bureau of Ocean Energy Management, Anchorage, AK, 265 p. plus appendices. 

Francis, R.C. and Hare, S.R. 1994. Decadal-scale regime shifts in the large marine ecosystems of 

the northeast Pacific: a case for historical science. Fisheries and Oceanography, 3, 279–291. 

Ilgen, A.G., Rychagov, S.N., and Trainor, T.P. 2011. Arsenic speciation and transport associated 

with the release of spent geothermal fluids in Mutnovsky Field (Kamchatka, Russia). 

Chemical Geology, 288, 115–132. 

Mantua, N.J. 2001. The Pacific Decadal Oscillation. In: Encyclopedia of Global Environmental 

Change, John Wiley & Sons, Inc., New York, NY. 

Mantua, N.J., Hare, S.R., Zhang, Y., Wallace, J.M., and Francis, R.C. 1997. A Pacific 

interdecadal climate oscillation with impacts on salmon production. Bulletin of the American 

Meteorological Society, 78, 1069–1079. 

13
Naidu, A.S., Misra, D., Kelley, J.J., Blanchard, A., and Venkatesan, M.I. 2011. Synthesis of timeinterval changes in trace metals and hydrocarbons in nearshore sediments of the Alaskan 

Beaufort Sea: a statistical analysis. Final Report, OCS Study BOEMRE 2011-031, Coastal 

Marine Institute, Fairbanks, AK, 76 p. 

Neff, J.M., Rabalais, N.N., and Boesch, D.F. 1987. Offshore oil and gas development activities 

potentially causing long-term environmental effects. In: Long-term environmental effects of 

offshore oil and gas development. Boesch, and Rabalais, Elsevier, New York, NY, 697 p. 

Neff, J.M. 2005. Composition, environmental fates, and biological effects of water-based drilling 

muds and cuttings discharged into the marine environment: a synthesis and annotated 

bibliography. Battele, Duxbury, MA, 73 p. 

Nelson, H. and Creager, J.S. 1977. Displacement of Yukon-derived sediment from Bering Sea to 

Chukchi Sea during Holocene time. Geology, 5, 141–146. 

Rember, R.D. and Trefry, J.H. 2004. Increased concentrations of dissolved trace metals and 

organic carbon during snowmelt in rivers of the Alaska arctic. Geochimica et Cosmochimica 

Acta, 68, 477–489. 

Swanson, F.J. 1981. Fires and geomorphic processes. In: Proceedings, fire regimes and 

ecosystems conference, Honolulu. General Technical Report WO-26, USDA, Washington, 

D.C., 401–420. 

Striegl, R.G., Dornblaser, M.M., Aiken, G.R., Wickland, K.P., and Raymond, P.A. 2007. Carbon 

export and cycling by the Yukon, Tanana, and Porcupine rivers, Alaska, 2001–2005. Water 

Resources Research, 43(2), WO2411, doi:10.1029/2006WR005201, 9 p. 

Trefry, J.H., Trocine, R.P., and Cooper, L.W. 2012. Distribution and provenance of trace metals 

in recent sediments of the northeastern Chukchi Sea. In Chukchi Sea Offshore Monitoring in 

Drilling Area (COMIDA): Chemical and Benthos (CAB). Final Report, OCS Study BOEM 

2012-012, Bureau of Ocean Energy Management, Anchorage, AK, 265 p. plus appendices. 

Trefry, J.H., Trocine, R.P., Cooper, L.W., and Dunton, K.H. 2014. Trace metals and organic 

carbon in sediments of the northeastern Chukchi Sea. Deep-Sea Research II, 102:18-31, doi: 

10.1016/j.dsr2.2013.07.018. 

Van Metre, P.C., Wilson, J.T., Fuller, C.C., Callender, E., and Mahler, B.J. 2004. Collection, 

analysis, and age-dating of sediment cores from 56 U.S. lakes and reservoirs sampled by the 

U.S. Geological Survey, 1992–2001. Scientific Investigations Report 2004-5184, U.S. 

Geological Survey, Washington, D.C. 

Westerling, A.L., Hidalgo, H.G., Cayan, D.R., and Swetnam, T.W. 2006. Warming and earlier 

spring increase in western U.S. forest wildfire activity. Science, 313, 940–943. 

14
APPENDIX

1. Dimethylcyclooctane 5. Decane 9. Octadecanoic Acid

2. Nitrobenzene-d5 (standard) 6. Phenol, 2,4-bis(1,1-dimethylethyl) 10. Tetrapentacontane, 1,54-dibromo3. Benzene, 1,3-bis(1,1-dimethylethyl 7. Nonadecane 11. (4-Methylphenyl)-methanediol diacetate

4. Eicosene 8. Hexadecanoic acid

 Figure A1: Organic compounds identified in the Arolokovik suspended water sample (06/13/2013). 

Table A1. Sampling site coordinates.

Site Latitude Longitude

Core Site 1 – YD1 62.645583 164.027000

Core Site 2 – YUK1 62.257 164.156861

Core Site 3 – Y1 61.558722 161.548917

Fish Village 62.572583 164.007389

Arolokovik 62.396417 163.801583

Mountain Village 62.165222 163.960472

Pitka’s Point 62.075000 163.474556

Pilot Station 61.954139 162.845111

15
Table A2: PAH targets and results of standards. Standards 1-7 were spiked with PAH targets to quantify counts at given 

are most common fragments of given compounds. Ratios are calculated to confirm fragments are from given targets. S

most common fragment masses are not confirmation of a target presence. D8 Naphthalene standards were added to clean s

confirm extraction efficiency, and values should be consistent through blanks and samples. Values that were below lower 

are shown as (-).

PAH Target 

Time of target Target blank 1 2 3 4 5 6 7

d8 naphthalene 136.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

7.036 108.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

137.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

136/108 NA NA NA NA NA NA NA NA 

136/137 NA NA NA NA NA NA NA NA 

108/137 NA NA NA NA NA NA NA NA 

Naphthalene 128.00 167.00 758.00 1488.00 3282.00 5063.00 10159.00 20650.00 39777.0

7.07 129.00 - - 223.00 381.00 472.00 1095.00 1909.00 4531.0

102.00 - - 144.00 313.00 416.00 816.00 1592.00 2598.0

128/129 NA NA 6.67 8.61 10.73 9.28 10.82 8.78 

128/102 NA NA 10.33 10.49 12.17 12.45 12.97 15.31 

129/102 NA NA 1.55 1.22 1.13 1.34 1.20 1.74 

Acenaphthylene 152.00 - 399.00 657.00 1620.00 3087.00 6549.00 14094.00 34736.0

10.26 151.00 - - 174.00 336.00 532.00 1212.00 3076.00 6823.0

76.00 - - 135.00 189.00 407.00 630.00 1372.00 3488.0

152/151 NA NA 3.78 4.82 5.80 5.40 4.58 5.09 

152/76 NA NA 4.87 8.57 7.58 10.40 10.27 9.96 

151/76 NA NA 1.29 1.78 1.31 1.92 2.24 1.96 

Acenaphthene 153.00 - 408.00 733.00 1307.00 2993.00 5962.00 13440.00 28176.0

10.64 154.00 - 361.00 579.00 1395.00 2643.00 5699.00 12744.00 26472.0

152.00 - 169.00 401.00 752.00 1440.00 2903.00 6214.00 13141.0

153/154 NA 1.13 1.27 0.94 1.13 1.05 1.05 1.06 

153/152 NA 2.41 1.83 1.74 2.08 2.05 2.16 2.14 

154/152 NA 2.14 1.44 1.86 1.84 1.96 2.05 2.01 

Fluorene 166.00 - 364.00 653.00 1398.00 2914.00 6029.00 13212.00 28056.0

12.1 165.00 - 320.00 772.00 1525.00 3001.00 6714.00 14940.00 30400.0

167.00 - - 125.00 231.00 415.00 862.00 1866.00 3960.0

166/165 NA 1.14 0.85 0.92 0.97 0.90 0.88 0.92 

166/167 NA NA 5.22 6.05 7.02 6.99 7.08 7.08 

165/167 NA NA 6.18 6.60 7.23 7.79 8.01 7.68 

16
Table A2 Continued.

PAH Target 

Time of target Target blank 1 2 3 4 5 6 7 d

Phenanthrene 178.00 - 473.00 992.00 2034.00 4352.00 9378.00 20496.00 45672.00

14.049 176.00 - 123.00 173.00 479.00 740.00 1636.00 3915.00 8357.00

179.00 - 113.00 200.00 359.00 675.00 1377.00 3350.00 6614.00

178/176 NA 3.85 5.73 4.25 5.88 5.73 5.24 5.47 

178/179 NA 4.19 4.96 5.67 6.45 6.81 6.12 6.91 

176/179 NA 1.09 0.87 1.33 1.10 1.19 1.17 1.26 

Anthracene 178.00 - 227.00 605.00 1153.00 2391.00 5348.00 12786.00 34928.00

14.169 176.00 - - 100.00 248.00 450.00 971.00 2477.00 6421.00

179.00 - - NA 163.00 387.00 938.00 1977.00 5039.00

178/176 NA NA 6.05 4.65 5.31 5.51 5.16 5.44 

178/179 NA NA NA 7.07 6.18 5.70 6.47 6.93 

176/179 NA NA NA 1.52 1.16 1.04 1.25 1.27 

Fluoranthene 202.00 - 308.00 570.00 1286.00 2898.00 5870.00 14250.00 36564.00

16.879 200.00 - - 111.00 233.00 594.00 1274.00 2980.00 7242.00

201.00 - - 136.00 230.00 430.00 824.00 2190.00 5321.00

202/200 NA NA 5.14 5.52 4.88 4.61 4.78 5.05 

202/201 NA NA 4.19 5.59 6.74 7.12 6.51 6.87 

200/201 NA NA 0.82 1.01 1.38 1.55 1.36 1.36 

Pyrene 202.00 - 395.00 719.00 1366.00 2828.00 6342.00 16396.00 38800.00

17.416 203.00 - - 140.00 244.00 679.00 1123.00 2993.00 6572.00

200.00 - - 182.00 298.00 646.00 1286.00 3287.00 7995.00

202/203 NA NA 5.14 5.60 4.16 5.65 5.48 5.90 

202/200 NA NA 3.95 4.58 4.38 4.93 4.99 4.85 

203/200 NA NA 0.77 0.82 1.05 0.87 0.91 0.82 

Benzo(a)anthracene 228.00 - 174.00 338.00 685.00 1119.00 2928.00 6845.00 21504.00

20.314 226.00 - - - 195.00 281.00 671.00 1779.00 5444.00

229.00 - - - 141.00 264.00 613.00 1425.00 4167.00

228/226 NA NA NA 3.51 3.98 4.36 3.85 3.95 

228/229 NA NA NA 4.86 4.24 4.78 4.80 5.16 

226/229 NA NA NA 1.38 1.06 1.09 1.25 1.31 

Chrysene 228.00 - 246.00 464.00 1124.00 2378.00 5738.00 15278.00 36030.00

20.394 226.00 - 122.00 157.00 309.00 698.00 1666.00 4495.00 9914.00

229.00 - - - 217.00 446.00 1194.00 3045.00 6985.00

228/226 NA 2.02 2.96 3.64 3.41 3.44 3.40 3.63 

228/229 NA NA NA 5.18 5.33 4.81 5.02 5.16 

226/229 NA NA NA 1.42 1.57 1.40 1.48 1.42 

17
PAH Target 

Time of target

Target bla

nk

1 2 3 4 5 6 7 d8 

Naphthal

Benzo(b)fluoranthene 252.00 - 187.00 366.00 672.00 1470.00 3339.00 7992.00 23528.00

22.726 126.00 - - - 113.00 349.00 644.00 1196.00 4120.00

253.00 - - 131.00 177.00 352.00 801.00 1725.00 5179.00

252/126 NA NA NA 5.95 4.21 5.18 6.68 5.71 NA 

252/253 NA NA 2.79 3.80 4.18 4.17 4.63 4.54 NA 

126/253 NA NA NA 0.64 0.99 0.80 0.69 0.80 NA 

Benzo(k)fluoranthene 252.00 - 161.00 299.00 682.00 1439.00 3355.00 9207.00 28163.00

22.783 253.00 - - 107.00 183.00 340.00 680.00 2193.00 6322.00

250.00 - - - 153.00 251.00 768.00 2016.00 5819.00

252/253 NA NA 2.79 3.73 4.23 4.93 4.20 4.45 NA 

252/250 NA NA NA 4.46 5.73 4.37 4.57 4.84 NA 

253/250 NA NA NA 1.20 1.35 0.89 1.09 1.09 NA 

Benzo(a)pyrene 252.00 - 133.00 278.00 531.00 1074.00 2247.00 4763.00 15953.00

23.4 126.00 - - - 133.00 245.00 504.00 834.00 2984.00

125.00 - - - 130.00 140.00 372.00 377.00 2134.00

252/126 NA NA NA 3.99 4.38 4.46 5.71 5.35 NA 

252/125 NA NA NA 4.08 7.67 6.04 12.63 7.48 NA 

126/125 NA NA NA 1.02 1.75 1.35 2.21 1.40 NA 

Dibenzo(a,h)anthracene 278.00 - 175.00 423.00 756.00 1582.00 3889.00 9449.00 27464.00

25.544 139.00 - - 112.00 117.00 286.00 725.00 1515.00 4207.00

279.00 - - 110.00 198.00 357.00 1012.00 2522.00 6592.00

278/139 NA NA 3.78 6.46 5.53 5.36 6.24 6.53 NA 

278/279 NA NA 3.85 3.82 4.43 3.84 3.75 4.17 NA 

139/279 NA NA 1.02 0.59 0.80 0.72 0.60 0.64 NA 

Indeno(1,2,3-cd)pyrene 276.00 - 161.00 297.00 584.00 1061.00 2681.00 5890.00 17432.00

25.492 277.00 - - - 155.00 279.00 681.00 1259.00 4024.00

274.00 - - - 169.00 221.00 684.00 1239.00 3532.00

276/277 NA NA NA 3.77 3.80 3.94 4.68 4.33 NA 

276/274 NA NA NA 3.46 4.80 3.92 4.75 4.94 NA 

277/274 NA NA NA 0.92 1.26 1.00 1.02 1.14 NA 

Benzo(ghi)perylene 276.00 - 165.00 359.00 772.00 1657.00 5416.00 9132.00 27240.00

25.949 277.00 - - - 187.00 420.00 1292.00 2115.00 6349.00

138.00 - - 118.00 239.00 433.00 1554.00 2536.00 7659.00

276/277 NA NA NA 4.13 3.95 4.19 4.32 4.29 NA 

276/138 NA NA 3.04 3.23 3.83 3.49 3.60 3.56 NA 

277/138 NA NA NA 0.78 0.97 0.83 0.83 0.83 NA 

Table A2 Continued

18
Table A3: PAH targets and results of core samples. D8 Naphthalene standards are added the samples to confirm extraction 

should be consistent through blanks and samples. Targets are most common fragments of given compounds. Ratios are calc

fragments are from given targets. Single responses of three most common fragment masses are not confirmation of a target 

were below lower level of detection (LLD) are shown as (-).

PAH Target 

Time of target

Target

PPB

YD 1-1 

20-23

YD 1-4 120-

123

YD 1-5 

163-166

YD 1-5 180-

183

YD 1-7 

260-263

YUK 1-1 1-

4

YUK 1-1 

30-33

YUK 1-3 

80-83

d8 naphthalene 136.00 5142.00 4581.00 5756.00 5621.00 5052.00 5444.00 6293.00 5574.00 

7.036 108.00 427.00 464.00 540.00 492.00 571.00 595.00 572.00 501.00 

137.00 518.00 639.00 639.00 632.00 616.00 632.00 733.00 646.00 

136/108 12.04 9.87 10.66 11.42 8.85 9.15 11.00 11.13 

136/137 9.93 7.17 9.01 8.89 8.20 8.61 8.59 8.63 

108/137 0.82 0.73 0.85 0.78 0.93 0.94 0.78 0.78 

Naphthalene 128.00 - - - - - - - - 

7.07 129.00 - - - - - - - - 

102.00 - - - - - - - - 

128/129 NA NA NA NA NA NA NA NA 

128/102 NA NA NA NA NA NA NA NA 

129/102 NA NA NA NA NA NA NA NA 

Acenaphthylene 152.00 - - - - - - - - 

10.26 151.00 - - - - - - - - 

76.00 - - - - - - - - 

152/151 NA NA NA NA NA NA NA NA 

152/76 NA NA NA NA NA NA NA NA 

151/76 NA NA NA NA NA NA NA NA 

Acenaphthene 153.00 - - - - - - - - 

10.64 154.00 - - - - - - - - 

152.00 - - - - - - - - 

153/154 NA NA NA NA NA NA NA NA 

153/152 NA NA NA NA NA NA NA NA 

154/152 NA NA NA NA NA NA NA NA 

Fluorene 166.00 - - - - - - - - 

12.1 165.00 - - - - - - - - 

167.00 - - - - - - - - 

166/165 NA NA NA NA NA NA NA NA 

166/167 NA NA NA NA NA NA NA NA 

165/167 NA NA NA NA NA NA NA NA 

19
Table A3 Continued.

PAH Target 

Time of target

Target

PPB

YD 1-1

20-23

YD 1-4 120-

123

YD 1-5 

163-166

YD 1-5 180-

183

YD 1-7 

260-263

YUK 1-1 1-

4

YUK 1-1 

30-33

YUK 1-3 

80-83

Phenanthrene 178.00 - - - - - - - - 

14.049 176.00 - - - - - - - - 

179.00 - - - - - - - - 

178/176 NA NA NA NA NA NA NA NA 

178/179 NA NA NA NA NA NA NA NA 

176/179 NA NA NA NA NA NA NA NA 

Anthracene 178.00 - - - - - - - - 

14.169 176.00 - - - - - - - - 

179.00 - - - - - - - - 

178/176 NA NA NA NA NA NA NA NA 

178/179 NA NA NA NA NA NA NA NA 

176/179 NA NA NA NA NA NA NA NA 

Fluoranthene 202.00 - - - - - - - - 

16.879 200.00 - - - - - - - - 

201.00 - - - - - - - - 

202/200 NA NA NA NA NA NA NA NA 

202/201 NA NA NA NA NA NA NA NA 

200/201 NA NA NA NA NA NA NA NA 

Pyrene 202.00 - - - - - - - - 

17.416 203.00 - - - - - - - - 

200.00 - - - - - - - 104.00 

202/203 NA NA NA NA NA NA NA NA 

202/200 NA NA NA NA NA NA NA NA 

203/200 NA NA NA NA NA NA NA NA 

Benzo(a)anthracene 228.00 - - - - - - - - 

20.314 226.00 - - - - - - - - 

229.00 - - - - - - - - 

228/226 NA NA NA NA NA NA NA NA 

228/229 NA NA NA NA NA NA NA NA 

226/229 NA NA NA NA NA NA NA NA 

Chrysene 228.00 - - - - - - - - 

20.394 226.00 - - - - - - - - 

229.00 - - - - - - - - 

228/226 NA NA NA NA NA NA NA NA 

228/229 NA NA NA NA NA NA NA NA 

226/229 NA NA NA NA NA NA NA NA 

20
PAH Target 

Time of target

Target

PPB

YD 1-1 20-

23

YD 1-4 120-

123

YD 1-5 

163-166

YD 1-5 180-

183

YD 1-7 

260-263

YUK 1-1 1-

4

YUK 1-1 

30-33

YUK 1-3 

80-83

Benzo(b)fluoranthene 252.00 - - - - - - - - 

22.726 126.00 - - - - - 193.00 - 130.00 

253.00 - - - - - - - - 

252/126 NA NA NA NA NA NA NA NA 

252/253 NA NA NA NA NA NA NA NA 

126/253 NA NA NA NA NA NA NA NA 

Benzo(k)fluoranthene 252.00 - - - - - - - - 

22.783 253.00 - - - - - - - - 

250.00 - - - - - - - - 

252/253 NA NA NA NA NA NA NA NA 

252/250 NA NA NA NA NA NA NA NA 

253/250 NA NA NA NA NA NA NA NA 

Benzo(a)pyrene 252.00 - - - - - - - - 

23.4 126.00 - - - - - 110.00 - - 

125.00 123.00 - 114.00 117.00 165.00 279.00 248.00 189.00 

252/126 NA NA NA NA NA NA NA NA 

252/125 NA NA NA NA NA NA NA NA 

126/125 NA NA NA NA NA 0.39 NA NA 

Dibenzo(a,h)anthracene 278.00 - - - - - - - - 

25.544 139.00 - - - - 115.00 132.00 114.00 146.00 

279.00 - - - - - - - - 

278/139 NA NA NA NA NA NA NA NA 

278/279 NA NA NA NA NA NA NA NA 

139/279 NA NA NA NA NA NA NA NA 

Indeno(1,2,3-cd)pyrene 276.00 - - - - - - - - 

25.492 277.00 - - - - - - - - 

274.00 - - - - - - - - 

276/277 NA NA NA NA NA NA NA NA 

276/274 NA NA NA NA NA NA NA NA 

277/274 NA NA NA NA NA NA NA NA 

Benzo(ghi)perylene 276.00 - - - - - - - - 

25.949 277.00 - - - - - - - - 

138.00 - - - - 112.00 154.00 - 139.00 

276/277 NA NA NA NA NA NA NA NA 

276/138 NA NA NA NA NA NA NA NA 

277/138 NA NA NA NA NA NA NA NA 

Table A3 Continued.

21
Table A4: Physical description of core samples.

YD1 YUK1 

Depth (cm) Sediment

Type Other Features

Depth 

(cm)

Sediment

Type Other Features

Depth 

(cm)

Sediment

Type 

2-5 sand upper 2 cm missing 1-4 clayey mud root present (removed) 0-3 clayey mud 

20-23 sand 10-13 clayey mud 5-6 clayey mud 

40-43 sand sand 20-23 clayey mud woody organics (removed) 10-11 clayey mud 

60-63 sand some Fe-oxide streaks 30-33 clayey mud 15-16 clayey mud 

80-83.5 sand 40-43 clayey mud Fe-oxide striping 20-21 clayey mud 

100-103 sand some Fe-oxide streaks 50-53 clayey mud Fe-oxide striping 25-26 clayey mud

120-123 sand 60-63 clayey mud Fe-oxide striping 30-31 clayey mud 

140-143 sand green foam covered core 70-73 clayey mud orange color 35-36 clayey mud 

163.2-166.5 sand mica present 80-83 clayey mud gray color 40-41 clayey mud 

180-183 sand mica present 90-93 clayey mud gray, Fe-oxide mottles 45-46 clayey mud

200-203 sand 100-103 clayey mud gray color 50-51 clayey mud 

220-223 sand some mica, Fe-oxide 110-113 clayey mud gray, Fe-oxide mottles

240-243 muddy silt 120-124 muddy clay

260-263 130-133 muddy clay large Fe-oxide mottle

280-283 140-143 clayey mud

302.5-305.5 sandy mud 300-302.5 removed prior 150-153 clayey mud

22
Table A5: Core sample radioisotope curve data values.

Core

Depth 

(cm) Pb-210 (Bq/g) 210 error

Pb-214 

(Bq/g) 214 error

Cs-137 

(Bq/g) Cs Error

YD1-1_2-5 3.5 0.021208225 0.003048 0.064123907 0.001045 0.001319944 0.0005

YD1-2_40-43 41.5 0.0310477 0.002828 0.033900521 0.000702 0.001548779 0.0004

YD1-3_80-83 81.5 0.027637934 0.005005 0.032572622 0.001319 0.001181228 0.0007

YD1-4_120-123 121.5 0.023885119 0.004428 0.031941066 0.00123 0.001066422 0.0005

YD1-5_163-166 164.5 0.022544548 0.005167 0.026021133 0.001306 0.003163933 0.0008

YD1-6_200-203 201.5 0.022058387 0.00487 0.02774328 0.00134 0.000934626 0.0006

YD1-7_240-243 241.5 0.035415219 0.005266 0.038484752 0.001305 0.003306853 0.0006

YD1-8_280-283 281.5 0.023649225 0.003957 0.037183567 0.001045 0.001029614 0.0005

YD1-8_302-305 303.5 0.025917305 0.004606 0.036588697 0.001204 0.001200741 0.0005

YUK1-1_1-4 2.5 0.035207407 0.003831 0.039592165 0.000978 -0.000229703 -0.002

YUK1-1_10-13 11.5 0.039392482 0.009096 0.037071599 0.002087 0.002316257 0.0011

YUK1-1_20-23 21.5 0.028935293 0.00719 0.032263927 0.001755 0.002370402 0.0009

YUK1-1_30-33 31.5 0.019974557 0.005589 0.035397769 0.001246 0.000678316 0.0005

YUK1-1_40-43 41.5 0.023738976 0.005448 0.036253728 0.001153 0.002505496 0.0008

YUK1-2_50-53 51.5 0.020580788 0.00609 0.034410027 0.001452 0.000984275 0.0004

YUK1-2_60-63 61.5 0.028553924 0.005197 0.032238158 0.001141 0.000237636 0.0005

YUK1-2_70-73 71.5 0.02293892 0.005141 0.034937568 0.001363 0.000805425 0.0007

YUK1-3_80-83 81.5 0.027380952 0.005755 0.036466855 0.00167 0.001389501 0.0005

YUK1-3_90-93 91.5 0.03834609 0.003328 0.035211331 0.000757 -3.84037E-05 -4E-04

YUK1-3_100-103 101.5 0.033468928 0.007095 0.034297222 0.001399 -0.00049158 -0.005

YUK1-3_110-113 111.5 0.017517934 0.006238 0.034142026 0.001349 0.000347215 0.0003

YUK1-4_120-124 122 0.01965187 0.005479 0.032534466 0.001467 0.012758977 0.0071

YUK1-4_130-133 131.5 0.036031345 0.005585 0.032734737 0.001381 0.000116534 0.0006

YI-0_0-3 1.5 0.06984977 0.008557 0.033154179 0.002085 0.007578897 0.0011

YI-0_5-6 5.5 0.023280856 0.030777 0.060521881 0.006482 0.008304348 0.0027

YI-0_10-11 10.5 0.134431961 0.032815 0.070447916 0.007925 0.048756535 0.0052

YI-0_15-16 15.5 0.042423336 0.007377 0.031559148 0.001628 0.003452559 0.0012

YI-0_20-21 20.5 0.064230835 0.016392 0.034871203 0.003829 0.008262044 0.0033

YI-0_25-26 25.5 0.064383066 0.013932 0.0355761 0.002778 -0.002944176 -0.029

YI-0_30-31 30.5 0.035882075 0.358821 0.045752359 0.004365 0.001053725 0.0032

YI-0_35-36 35.5 0.077579893 0.024701 0.040893515 0.004531 -0.004097826 -0.041

YI-0_40-41 40.5 0.052219616 0.015504 0.047189871 0.003969 0.001080883 0.0018

YI-0_45-46 45.5 0.037688923 0.016707 0.035712638 0.006453 0.018584313 0.006

YI-1_50-51 50.5 0.043564797 0.007833 0.030548784 0.00198 0.001639189 0.0012

23
As the Nation’s principal conservation agency, the Department of the Interior has 

responsibility for most of our nationally owned public lands and natural 

resources. This includes fostering the sound use of our land and water 

resources, protecting our fish, wildlife and biological diversity; preserving the 

environmental and cultural values of our national parks and historical places; and 

providing for the enjoyment of life through outdoor recreation.The Department 

assesses our energy and mineral resources andworks to ensure that their 

development is in the best interests of all our people by encouraging stewardship 

and citizen participation in their care. The Department also has a major 

responsibility for American Indian reservation communities and for people who 

live in island communities.

The Bureau of Ocean Energy Management 

The Bureau of Ocean Energy Management (BOEM) works to manage the 

exploration and development of the nation's offshore resources in a way that 

appropriately balances economic development, energy independence, and 

environmental protection through oil and gas leases, renewable energy 

development and environmental reviews and studies.

The Department of the Interior Mission