U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2007–1347

Total Selenium and Selenium Species in Irrigation Drain 

Inflows to the Salton Sea, California, April and July 2007

Total Selenium and Selenium Species in 

Irrigation Drain Inflows to the Salton Sea, 

California, April and July 2007

By Thomas W. May, Michael J. Walther, Michael K. Saiki, and 

William G. Brumbaugh 

Open-File Report 2007–1347

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

May, T.W., Walther, M.J., Saiki, M.K., and Brumbaugh, W.G., 2007, Total selenium and selenium species in irrigation 

drain inflows to the Salton Sea, California, April and July 2007: U.S. Geological Survey Open-File Report 2007–1347, 

17 p. 
iii

Contents

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

Introduction.....................................................................................................................................................1

Methods...........................................................................................................................................................1

Field Collection and Preservation ......................................................................................................1

Sampling History...................................................................................................................................2

Homogenization and Lyophilization ...................................................................................................2

Chemical Procedures...........................................................................................................................3

Instrumental Analysis...........................................................................................................................3

Quality Assurance..........................................................................................................................................4

Results .............................................................................................................................................................4

Quality Control Results................................................................................................................................12

References Cited..........................................................................................................................................17

Tables

1. Total selenium concentrations in duplicates of unfiltered irrigation drain water 

samples, Salton Sea, California, April 2007 ..............................................................................5

2. Total selenium concentrations in duplicates of unfiltered irrigation drain water 

samples, Salton Sea, California, July 2007 ...............................................................................6

3. Total dissolved selenium, dissolved selenium species, and particulate selenium 

concentrations in filtered irrigation drain water samples, Salton Sea, April 2007 ............7

4. Total suspended solids concentrations in unfiltered Salton Sea irrigation drain 

water samples, April and July 2007 ...........................................................................................8

5. Selenium concentrations in biota samples collected from Salton Sea irrigation 

drains, April 2007...........................................................................................................................9

6. Selenium concentrations in detritus and sediment samples collected from 

Salton Sea irrigation drains, April 2007...................................................................................13

7. Particle size distributions in sediment samples collected from Salton Sea 

irrigation drains, April 2007 .......................................................................................................15

8. Percent total organic carbon in sediment samples collected from Salton Sea 

irrigation drains, April 2007 .......................................................................................................16
iv

Conversion Factors

Multiply By To obtain

Length

millimeter) 0.03937 inch (in.)

micrometer (μm) 0.0000393 inch (in.)

Volume

liter (L) 33.82 ounce, fluid (fl. oz)

milliliter (mL) 0.034 ounce, fluid (fl. oz)

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

milligram (mg) 0.000035 ounce (oz)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

 °F=(1.8×°C)+32

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L) or 

micrograms per liter (μg/L). .

Concentrations of chemical constituents in solid materials are given in micrograms per gram 

(μg/g).
Abstract

This report presents the results for two sampling 

periods during a 4-year monitoring survey to provide a 

characterization of selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total 

selenium, selenium species, and total suspended solids were 

determined in water samples, and total selenium was determined in sediment, detritus, and biota that included algae, 

plankton, midge larvae (family, Chironomidae), and two 

fish species—western mosquitofish (Gambusia affinis), and 

sailfin molly (Poecilia latipinna). In addition, sediments 

were analyzed for percent total organic carbon and particle size. Total selenium concentrations in water for both 

sampling periods ranged from 1.43 to 47.1 micrograms per 

liter, predominately as selenate, which is typical of waters 

leached out of selenium-contaminated marine shales under 

alkaline and oxidizing conditions. Total selenium concentrations ranged from 0.88 to 20.2 micrograms per gram 

in biota, and from 0.15 to 28.9 micrograms per gram in 

detritus and sediment. 

Introduction

Monitoring surveys are being conducted for 4 years to 

provide a profile of selenium concentrations in selected irrigation drain inflows to the Salton Sea, California. The objective 

is to determine total selenium, selenium species, and total 

suspended solids in water samples, and total selenium in sediment, detritus, and biota that include algae, plankton, midge 

larvae (family, Chironomidae), and two fish species—western 

mosquitofish (Gambusia affinis) and sailfin molly (Poecilia 

latipinna). In addition, sediments are analyzed for percent 

total organic carbon and particle size. The results described 

in this report were obtained by the U.S. Geological Survey 

(USGS) Columbia Environmental Research Center (CERC) 

and Western Fisheries Research Center (WFRC) during April 

and July 2007. 

Methods

Field Collection and Preservation

The USGS-WFRC sample collectors used the laboratory at the U. S. Fish and Wildlife Service Sonny Bono Salton 

Sea National Wildlife Refuge (henceforth referred to as “the 

Refuge” in this report) for certain aspects of sample processing and for preparing samples for shipment during field trips 

to irrigation drains. 

Unfiltered Water: Each total selenium water sample was 

poured through a 1-millimeter (mm) polypropylene sieve 

attached to a 1-liter (L) pre-cleaned borosilicate glass bottle. 

Upon collection, the water sample was acidified to less than 

pH 2 with 6 normal (N) hydrochloric acid (HCl), chilled to 

approximately 4 degrees Celsius (~4 oC), and kept in the dark 

during transport to the USGS-CERC. Each water sample 

intended for analysis of total suspended solids (TSS) was 

poured through a 1-mm polypropylene sieve attached to a 

pre-cleaned wide-mouth 1-L polypropylene bottle. The TSS 

samples were chilled (~4 oC) during transport to the USGSCERC.

Filtered Water: Water for selenium speciation was filtered 

using a Geotech® peristaltic pump that was equipped with a 

standard pumphead and high capacity 0.45 micrometer (μm) 

filter capsule certified for trace element background. All 

tubing was acid-cleaned silicone; a new length was used at 

each site and for the blank. At each site, 1 L of deionized (DI) 

water was filtered through the filter capsule followed by site 

water. The first 200 milliliters (mL) of site water eluant was 

discarded, then 1 L of eluant was collected in an acid-cleaned 

1-L borosilicate glass bottle, acidified, and stored as described 

earlier for unfiltered water.

Particulates: A polycarbonate Geotech® 142-mm plate 

filter apparatus was used with a 142-mm 0.4 μm polycarbonate 

filter. At each site, 0.5 L of DI water was filtered through the 

plate filter, followed by up to 1 L of site water; after volume 

notation, the filtrate was discarded. Each filter was placed in 

a pre-cleaned plastic petri dish (150 mm x 15 mm) with the 

particulate side up and sealed with its corresponding cover for 

Total Selenium and Selenium Species in Irrigation Drain 

Inflows to the Salton Sea, California, April and July 2007

By Thomas W. May, Michael J. Walther, Michael K. Saiki, and William G. Brumbaugh
2 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

freezer storage and transport to the USGS-CERC. The plate 

filtration unit was rinsed with 0.1 percent nitric acid (HNO3) 

followed by a DI water rinse after sampling was completed at 

each site. 

Sediment: Five sampling points for sediment collection 

were identified along the length of each drain sampled. At 

each sampling point, sediment was collected with a stainless 

steel dredge. The dredge was cleared of mud and rinsed with 

site water while used within a drain; at a new site, the dredge 

was rinsed with DI water followed by site water before the 

first sample was collected. From each of the five sampling 

points for a drain, enough sediment to fill a 250-mL container 

was collected and mixed to form a composite sample. An aliquot of the composite was then placed into a 120- and 500-mL 

polypropylene container. All containers were placed on ice in 

the field. Samples were chilled (~4 0C) during transport to the 

USGS-CERC. 

Midge larvae and detritus: An insect sweep net was 

used to collect samples of midge larvae and detritus, which 

were then sorted and hand-picked with plastic tweezers in a 

polypropylene sieve, and stored temporarily in a plastic foodstorage container on ice. After rinsing with DI water, samples 

were wrapped in plastic wrap, stored in separate plastic bags, 

and frozen.

Fish: Western mosquitofish and sailfin molly composite 

samples were collected with seine nets and minnow traps; 

sampled material from each site was stored temporarily in 

a plastic food-storage container on ice. Upon return to the 

Refuge lab, the whole-body fish were measured for standard 

length, weighed, and rinsed with DI water. Each fish composite sample (n=36) was wrapped in plastic wrap and placed into 

a plastic bag and frozen. 

Algae and Plankton: If available, algae were collected 

from floating masses or scraped from sticks and rocks at each 

drain site and stored temporarily in a sealable plastic foodstorage container on ice. Following collection, the material 

was rinsed with DI water, wrapped with plastic wrap, stored 

in a sealable plastic bag, and frozen. Plankton was collected 

with a tow net; after draining off site water, each sample was 

rinsed three times with DI water. The plankton and the DI rinsing water were placed in a 120-mL polypropylene container. 

Collected samples were stored on ice in the field and frozen 

immediately upon return to the Refuge.

Sampling History

The irrigation drain monitoring samples that are the 

subject of this report were received in six shipments and were 

collected by personnel of the USGS-WFRC. Shipments were 

received by the Environmental Chemistry Branch Inorganic 

Section (henceforth referred to as “the lab” in this report) of 

the USGS-CERC shortly after collection to meet the 7-day 

holding time specified for TSS in water and the 14-day holding time for total organic carbon (TOC) in sediments. 

The first set of samples was collected from April 19–21, 

2007, received by the lab on April 24, 2007, and contained 

13 TSS water samples, 1 TOC sediment sample, and 1 total 

selenium sediment sample. The samples were assigned USGSCERC batch number 1354 and USGS-CERC sample identification numbers 39247–39261.

The second set of samples was collected from April 

19–24, 2007, received by the lab on April 26, 2007, and 

contained 7 TSS water samples, 19 total selenium sediment 

samples, and 18 TOC sediment samples. The samples were 

assigned USGS-CERC batch number 1355 and USGS-CERC 

sample identification numbers 39262– 39305. 

The third set of samples was collected from April 24–28, 

2007, received by the lab on May 1, 2007, and contained 11 

TSS water samples, 12 TOC sediment samples, and 11 total 

selenium water samples. The samples were assigned USGSCERC batch number 1357 and USGS-CERC sample identification numbers 39313–39346.

The fourth set of samples was collected from April 

17–May 7, 2007, and received by the lab on May 8, 2007, and 

contained 48 total selenium water samples and 17 dissolved 

selenium water samples. The samples were assigned USGSCERC batch number 1360 and USGS-CERC sample identification numbers 39371–39435.

The fifth set of samples was collected during April 

17–May 3, 2007, received by the lab on May 24, 2007, and 

contained 36 fish samples, 21 algae samples, 21 invertebrate 

samples, 21 detritus samples, 21 plankton samples, and 15 

particulate samples. The samples were assigned USGS-CERC 

batch number 1364 and USGS-CERC sample identification 

numbers 39503–39637.

The sixth set of samples was collected from July 12–13, 

2007, received by the lab on July 17, 2007, and contained 31 

TSS water samples and 62 total selenium water samples. The 

samples were assigned USGS-CERC batch number 1375 and 

USGS-CERC sample identification numbers 39247–39261.

Homogenization and Lyophilization

Frozen fish samples were minced with a small ceramic 

knife before freeze drying. Particulates, biota, detritus, and 

sediment samples were lyophilized in a Virtis Genesis® 35EL 

freeze dryer and percent moisture was determined as part of 

the lyophilization process; however, percent moisture was not 

determined for plankton samples because the sample matrix 

included DI water. After lyophilization, all midge larvae, detritus, plankton, algae, and fish samples were homogenized by 

grinding with a glass rod against the container surface. Dried 

sediment was placed into a plastic bag, sealed, and then further 

reduced by using a rolling pin on the plastic bag to produce a 

coarse powder product. Dried filters containing particulates 

did not require any additional homogenization after freeze drying. 
Methods 3

Chemical Procedures

Total Selenium in Water: Before analysis, all water 

samples were stored in the dark and at ~4 oC. For the subsequent determination of total selenium in filtered and unfiltered 

samples, a 20-mL aliquot of each acidified water sample was 

subjected to an HNO3–magnesium nitrate [Mg(NO3)

2

] ashing 

procedure followed by treatment with HCl. The ashing procedure consisted of three steps: boiling with HNO3

 for solubilization and partial oxidation, ashing at 500 o

C with Mg(NO3)

2

to complete the oxidation and decompose remaining organic 

matter, and heating with HCl to dissolve the ash and reduce 

selenium to the selenite (Se+4) oxidation state required for 

detection by hydride generation atomic absorption spectrophotometry. Following reduction, digestates were diluted to ~100 

mL with DI water, yielding a final acid matrix of 10 percent 

HCl.

Selenite + Selenate in Water: Ten mL of filtered water 

and 5 mL of concentrated HCl were placed in a 25-mL borosilicate test tube and heated to 120–125 o

C in a well incubator 

block for 2–3 hours. After cooling, the liquid was transferred 

into a 60-mL polyethylene bottle and the final volume was 

adjusted to 50 mL with DI water; final matrix was 10 percent 

HCl.

Filtered Particulates: A dried filter containing particulates was rolled up, cut into pieces, and the entire filter was 

put into a 100-mL glass beaker. The filter was then subjected 

to the ashing procedure as described ealier for total selenium 

in water. The same procedure was conducted on clean filters, 

which served as blanks.

Biota, Detritus, and Sediment: An ~0.25-gram (g) 

aliquant of each dried sample was subjected to a HNO3–

Mg(NO3)

2

 ashing procedure followed by HCl reduction for 

the determination of selenium. The steps in the procedure are 

the same as those described above for total selenium in water. 

Digestates were diluted to ~100 mL with DI water, yielding a 

final acid matrix of 10 percent HCl.

Instrumental Analysis

Total Selenium: Total selenium was determined in all 

ashed samples by flow injection hydride generation atomic 

absorption spectrophotometry (FIHGAAS). In this procedure, 

the digestate is mixed with an HCl-carrier solution, and then 

reduced by sodium tetrahydridoborate that has been stabilized 

with sodium hydroxide. Selenium in the sample is converted to 

volatile hydrogen selenide and transferred with argon carrier 

gas into a heated quartz cell mounted on an atomic absorption 

spectrophotometer for decomposition into atomic vapor and 

measurement. 

Selenite in Water: An aliquot of each filtered water 

sample was analyzed directly by FIHGAAS after acidification 

to 10 percent HCl.

Selenate and Selenite in Water: Filtered water samples 

were subjected to heating for 1 hour with HCl to reduce the 

selenate species to selenite. Samples prepared in this manner 

were analyzed directly by FIHGAAS to provide selenate + 

selenite concentrations. The selenate concentration was calculated by difference using the formula: 

selenate = (selenate + selenite) – selenite (1)

Particulate Selenium in Water: Selenium associated with 

filtered particulates was determined by analyzing ashed filters 

by FIHGAAS. The mass of selenium in micrograms for the 

particulates was divided by the volume of water filtered for 

each drain site (0.5 or 1.0 L) to produce a microgram per liter 

concentration.

Dissolved Organic Selenium in Water: Dissolved organic 

selenium was estimated using the following formula: 

dissolved organic selenium = total dissolved selenium – 

(selenate + selenite) (2)

Total Suspended Solids: Upon arrival at the USGSCERC, all TSS samples were transferred to the Ecology 

Branch for TSS analysis. Total suspended solids were analyzed with methods recommended by the American Public 

Health Association (1998). Samples were brought to room 

temperature and mixed with a magnetic stirrer and subsequent 

manual inversions of the sample container. The sample was 

measured into a graduated cylinder, poured into a filtration 

apparatus, and filtered through a ProWeigh® glass fiber filter. 

The samples were pre-washed three times in DI water, dried 

at 105 °C, and weighed to the nearest 0.1 milligram (mg). 

Sample volume varied to yield a dried residue between 2.5 and 

200 mg. For each volume of sample used, an equal volume 

of DI water also was filtered for a blank determination. After 

filtering, large or non-homogeneous materials were removed 

from the filter, and the filter was rinsed with three 10-mL aliquots of DI water. Filters were then dried for at least 1 hour in 

a 103–105 °C oven and cooled to room temperature in a dessicator; filter and residue were weighed to the nearest 0.0001 

g. Drying, cooling, and weighing of the filter were repeated 

until the weight difference was less than (<) 4 percent or 0.5 

mg, whichever was less. The average of these weights was 

used to determine the constant weight of the filter and residue, 

which was then corrected for any weight gain or loss of the 

blank. After subtracting the filter weight, this blank corrected 

dried residue in milligrams was divided by the sample volume 

in liters to yield TSS in milligrams per liter. 

Particle-size Analysis: Sediment samples designated for 

particle size analysis (PSA) were transferred to the USGSCERC Ecology Branch upon arrival. The method requires 

use of a Bouyoucos hydrometer, adapted from American 

Society of Testing and Materials (2003). Wet sediment was 

sieved through a 2-mm sieve to remove any particles larger 

than coarse sand, and then dried at 60 oC using a convectional 

drying oven. Approximately 100 g of dried sediment was 

mixed with 250 mL of DI water and 100 mL of a 50 mg/L 

sodium hexametaphosphate solution. A stir bar was added and 
4 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

the mixture was stirred with a magnetic stirring plate. After 

calibrating the hydrometer, the suspended sediment mixture 

was transferred to a sedimentation cylinder and the volume 

adjusted to 1 L with DI water. After allowing for thermal 

equilibration, the temperature was recorded. Cylinder contents were then thoroughly mixed followed by insertion of the 

hydrometer into the suspension. The meniscus reading was 

taken after 30 seconds and the hydrometer was removed and 

dried. After 120 minutes, the hydrometer was reinserted and 

the meniscus read again. All hydrometer meniscus readings 

were corrected by adjusting +0.25 for each degree above 18 oC 

and -0.25 for each degree below 18 oC. Percent fractions were 

determined as follows:

grams sand = sediment dry weight – (corrected 30 second 

reading – corrected calibration); 

percent sand = grams sand/sediment dry weight x 100;

grams clay = sediment dry weight – (corrected 120 

minute reading – corrected calibration); 

percent clay = grams clay/sediment dry weight x 100;

percent silt = 100 – (percent sand + percent clay). 

Total Organic Carbon: TOC was determined with a 

Universal Instruments Corporation (UIC) Model 5014 Coulometer that determines carbon in any carbon dioxide (CO2

 ) 

containing gas stream (UIC, 1999). The coulometer is used as 

a detector with different carbon front-end units and can detect 

carbon in the range of 0.01 micrograms (μg) to 100 mg. The 

coulometer cell is filled with a proprietary solution containing 

monoethanolamine and a colorimetric pH indicator. Platinum 

(cathode) and silver (anode) electrodes are positioned in the 

cell. The cell assembly is then placed in the coulometer cell 

compartment between a light source and a photodetector in 

the coulometer. As a CO2 gas stream passes into the cell, the 

CO2 is quantitatively absorbed, reacting with the monoethanolamine to form a titratable acid. This acid causes the color 

indicator to fade. A photodetector monitors the change in the 

color of the solution as a percent transmittance (%T). As the 

%T increases, the titration current is automatically activated 

to electrochemically generate base at a rate proportional to 

the %T (approximately 1,500 μg carbon/minute). When the 

solution returns to its original color (original %T), the current 

stops. 

For TOC analysis, total carbon (TC, μg/mg) and total 

inorganic carbon (TIC, μg/mg) are determined. Total carbon 

is determined by combustion of weighed sediments at 925 0C. 

In TIC analysis, weighed sediments are exposed to heated 2 

Normal sulfuric acid. Any inorganic carbonates are reduced to 

mineral components and CO2 gas. The gas is carried in high 

purity oxygen to the coulometer cell, where it is measured by 

the procedure described above. Percent TOC is calculated as 

follows:

Percent TOC = [(TC – TIC)/1000] x 100

Quality Assurance

Samples were processed through the preparative and 

analytical flow scheme in 14 analytical blocks for selenium, 

2 blocks for TSS, and 1 block each for PSA and TOC. Each 

block was assigned a block initiation date (BID) used to identify samples and quality-control samples/materials prepared 

and analyzed collectively as a unit. For samples analyzed 

by atomic absorption for total selenium, pre-digestion quality 

control included digestion blanks, replicates, spikes, and reference solutions. Analytical quality control for selenium included 

calibration verification solutions, replicate analyses, and analysis 

spikes. Quality control for the TSS determination included a 

reference solution, duplicates, and replicates. Quality control for 

sediment PSA and TOC included duplicates and replicates.

Results

Total Selenium: Total selenium concentrations [micrograms per liter, (μg/L)] in unfiltered water samples for the 

April 2007 samples are listed in table 1. Mean selenium 

concentrations were most elevated in water from drain Trifolium Storm (47.1) followed by drain Q (15.9). The lowest 

mean selenium concentration was from drain S (1.57). Data 

for the July 2007 samples are listed in table 2. Mean selenium 

concentrations were again highest in Trifolium Storm (30.9) 

followed by Trifolium 18 (17.2). The lowest mean selenium 

concentration was from Trifolium 14 and T (1.43).

Total Dissolved Selenium and Selenium Species: Dissolved selenite, dissolved selenate, dissolved organic selenium, 

total dissolved selenium, and particulate selenium concentrations (μg/L) from filtered water samples collected during the 

April 2007 sampling are presented in table 3. The dissolved 

organic selenium fraction is assumed to include seleno-amino 

acids and dissolved seleno- peptides, Se(0) as a pseudodissolved microcolloid, and inorganic Se(-II) species (Cutter, 

1984). Speciation revealed that selenium in the sampled drains 

exists predominately as selenate (85 to 95 percent) followed 

by selenite (5 to 15 percent), typical of waters where selenium 

is leached out of selenium-contaminated marine shales under 

alkaline and oxidizing conditions. 

Total Suspended Solids: TSS concentrations (mg/L) in 

unfiltered water collected during the April and July 2007 

samplings are presented in table 4. TSS concentrations ranged 

from a high of 429 (Z Spill) to a low of 16.6 (San Felipe 

Wash). 

Biota: Percent moisture and concentrations of selenium 

[micrograms per gram (μg/g) dry weight] in biota [algae, 

plankton, midge larvae, western mosquitofish (Gambusia 

affinis), and sailfin molly (Poecilia latipinna)] are presented in 

table 5. Selenium concentration ranges for each matrix were 

as follows: algae, 0.88 to 5.74; plankton, 1.40 to 17.0; midges, 

3.18 to 13.4; fish, 3.85 to 20.2.
Results 5

Table 1. Total selenium concentrations in duplicates of unfiltered irrigation drain water samples, Salton Sea, California, April 

2007.

[USGS, U.S. Geological Survey; ID, identification; Rep, field replicate; μg/L, microgram per liter; SD, standard deviation; ---, no data; <, less than; nc, 

not collected]

USGS ID Field ID Drain Collection date

Total selenium concentration

Rep 1 SD

(μg/L)

Rep 2

(μg/L)

Mean

(μg/L)

39417 BLANK-1 --- 05/08/07 < 0.10 --- --- ---

39418 BLANK-2 --- 05/08/07 < 0.10 --- --- ---

39415 BLNDWATSE08 --- 04/19/07 5.73 --- --- ---

39416 BLNDWATSE08B --- 04/27/07 3.47 --- --- ---

39413, 39414 LKLNWATSE Lack & Linsey Pond 04/20/07 4.12 4.27 4.19 0.11

39371, 39372 NLD1WATSE Niland 1 04/23/07 2.94 2.75 2.85 0.14

39373, 39374 NLD2WATSE Niland 2 04/24/07 3.03 3.05 3.04 0.01

39375, 39376 NLD3WATSE Niland 3 04/24/07 2.07 2.02 2.04 0.04

39377, 39378 NLD4WATSE Niland 4 04/24/07 1.91 2.06 1.98 0.11

nc1 OOOOWATSE O --- --- --- --- ---

39389, 39390 PPPPWATSE P 04/27/07 3.50 3.45 3.48 0.04

nc1 POEDWATSE Poe Rd --- --- --- --- ---

39391, 39392 PUMCWATSE Pumice 04/21/07 7.04 6.86 6.95 0.13

39387, 39388 QQQQWATSE Q 04/27/07 15.7 16.1 15.9 0.22

39385, 39386 RRRRWATSE R 04/27/07 2.84 2.80 2.82 0.03

39383, 39384 SSSSWATSE S 04/27/07 1.60 1.53 1.57 0.05

39399, 39400 SFWHWATSE San Felipe Wash 04/19/07 2.81 2.82 2.82 0.01

nc1 TTTTWATSE T --- --- --- --- ---

39407, 39408 TR01WATSE Trifolium 1 04/26/07 4.04 3.96 4.00 0.05

39411, 39412 TR12WATSE Trifolium 12 04/26/07 3.66 3.59 3.63 0.05

39405, 39406 TR13WATSE Trifolium 13 04/21/07 5.76 5.60 5.68 0.11

nc1 TR14WATSE Trifolium 14 --- --- --- --- ---

nc1 TR18WATSE Trifolium 18 --- --- --- --- ---

39403, 39404 TR19WATSE Trifolium 19 04/20/07 3.11 3.13 3.12 0.01

39395, 39396 FT20WATSE Former Trifolium 20 04/19/07 5.76 5.83 5.80 0.05

nc1 TR20WATSE Trifolium 20 --- --- --- --- ---

39397, 39398 TR22WATSE Trifolium 22 04/19/07 7.8 7.5 7.6 0.20

39401, 39402 TR23WATSE Trifolium 23 04/19/07 4.02 3.63 3.83 0.28

39409, 39410 TRSTWATSE Trifolium Storm 04/26/07 47.3 46.9 47.1 0.26

39381, 39382 UUUUWATSE U 04/24/07 2.17 2.07 2.12 0.07

39393, 39394 VLO5WATSE Vail 5 04/26/07 4.36 6.33 5.35 1.40

39379, 39380 WWWWWATSE W 04/24/07 4.15 3.87 4.01 0.20

nc1 ZSPLWATSE Z Spill --- --- --- --- ---

1

Drain was one of seven selected for intensive sampling (see table 3).
6 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

Table 2. Total selenium concentrations in duplicates of unfiltered irrigation drain water samples, Salton Sea, California, July 2007.

[USGS, U.S. Geological Survey; ID, identification; Rep, field replicate; μg/L, micrograms per liter; SD, standard deviation; <, less than]

USGS ID Field ID Drain Collection 

date

Total selenium concentration

Rep 1 SD

(μg/L)

Rep 2

(μg/L)

Mean

(μg/L)

39852 BLANK-1 --- 07/17/07 < 0.19 --- ---

39853 BLANK-2 --- 07/17/07 < 0.19 --- ---

39820 BLNDWATSE09B --- 07/12/07 1.45 --- --- ---

39849 BLNDWATSE09A --- 07/12/07 10.1 --- --- ---

39818,39819 LKLNWATSE09 Lack & Linsey Pond 07/12/07 4.06 4.16 4.11 0.07

39821,39822 NLD1WATSE09 Niland 1 07/13/07 2.29 2.20 2.24 0.06

39823,39824 NLD2WATSE09 Niland 2 07/13/07 2.43 2.48 2.46 0.03

39825,39826 NLD3WATSE09 Niland 3 07/13/07 2.21 2.72 2.46 0.36

39827,39828 NLD4WATSE09 Niland 4 07/13/07 2.05 1.95 2.00 0.07

39845,39846 OOOOWATSE09 O 07/13/07 3.77 3.84 3.81 0.05

39841,39844 PPPPWATSE09 P 07/13/07 2.6 2.7 2.6 0.03

39802,39803 POEDWATSE09 Poe Rd 07/12/07 4.64 4.58 4.61 0.04

39847,39848 PUMCWATSE09 Pumice 07/13/07 5.13 5.18 5.15 0.04

39842,39843 QQQQWATSE09 Q 07/13/07 8.62 8.70 8.66 0.06

39839,39840 RRRRWATSE09 R 07/13/07 3.93 3.94 3.93 0.01

39837,39838 SSSSWATSE09 S 07/13/07 2.17 2.13 2.15 0.03

39796,39797 SFWHWATSE09 San Felipe Wash 07/12/07 2.11 2.26 2.18 0.11

39835,39836 TTTTWATSE09 T 07/13/07 1.45 1.40 1.43 0.03

39812,39813 TR01WATSE09 Trifolium 1 07/12/07 4.25 4.09 4.17 0.11

39816,39817 TR12WATSE09 Trifolium 12 07/12/07 6.7 7.0 6.9 0.20

39808,39809 TR13WATSE09 Trifolium 13 07/12/07 3.53 3.34 3.44 0.13

39810,39811 TR14WATSE09 Trifolium 14 07/12/07 1.39 1.47 1.43 0.06

39800,39801 TR18WATSE09 Trifolium 18 07/12/07 17.7 16.6 17.2 0.80

39804,39805 TR19WATSE09 Trifolium 19 07/12/07 1.84 1.71 1.77 0.09

39792,39793 FT20WATSE09 Former Trifolium 20 07/12/07 5.78 5.84 5.81 0.04

39806,39807 TR20WATSE09 Trifolium 20 07/12/07 4.2 4.1 4.1 0.07

39794,39795 TR22WATSE09 Trifolium 22 07/12/07 9.3 9.4 9.4 0.06

39798,39799 TR23WATSE09 Trifolium 23 07/12/07 3.9 3.8 3.8 0.04

39814,39815 TRSTWATSE09 Trifolium Storm 07/12/07 31.3 30.4 30.9 0.62

39833,39834 UUUUWATSE09 U 07/13/07 1.83 1.91 1.87 0.06

39850,39851 VLO5WATSE09 Vail 5 07/13/07 2.97 2.94 2.96 0.02

39831,39832 WWWWWATSE09 W 07/13/07 4.29 4.35 4.32 0.04

39829,39830 ZSPLWATSE09 Z Spill 07/13/07 5.33 4.34 4.83 0.70
Results 

7

Table 3. Total dissolved selenium, dissolved selenium species, and particulate selenium concentrations in filtered irrigation drain water samples, Salton Sea, April 2007.[USGS, U.S. Geological Survey; ID, identification; Rep, replicate; [Se03]-2, selenite; [Se04]-2, selenate; Se, selenium; μg/L, micrograms per liter; ---, no data; <, less than; bold italicized values are greater than method quantification limit, but less than method detection limit; these values have high uncertainty and are presented for information purposes only]

USGS ID Field ID Drain Rep number Collection date Dissolved [Se03]-2 (μg/L) Calculated dissolved1 [Se04]-2 (μg/L) Calculated dissolved2 organic Se (μg/L) Measured total dissolved Se (μg/L) Measured particulate3 Se (μg/L) Calculated total4 Se (μg/L)

39434 BLANK-1 --- 1 05/07/07 < 0.03 < 0.10 --- < 0.10 0.003 ---39435 BLANK-2 --- 2 05/07/07 < 0.03 < 0.10 --- < 0.10 0.003 ---

39433,39629 BLIND --- --- 04/20/07 1.17 22.7 0.00 23.6 0.11 23.739423,39636 OOOOWATSE O 1 04/28/07 0.49 3.27 0.24 4.00 0.10 4.1039424,39637 OOOOWATSE O 2 04/28/07 0.48 3.41 0.21 4.10 0.11 4.2239427,39623 POEDWATSE Poe Rd 1 04/17/07 0.50 7.8 0.98 9.23 0.019 9.239428,39624 POEDWATSE Poe Rd 2 04/17/07 0.50 7.4 1.81 9.72 0.015 9.739421,39634 TTTTWATSE T 1 04/27/07 0.16 1.67 0.00 1.04 0.030 1.0739422,39635 TTTTWATSE T 2 04/27/07 0.16 0.70 0.23 1.10 0.032 1.1339431,39630 TR14WATSE Trifolium 14 1 04/21/07 0.36 1.94 0.00 2.20 0.067 2.2639432,39631 TR14WATSE Trifolium 14 2 04/21/07 0.39 1.47 0.29 2.14 0.066 2.2039425,39627 TR18WATSE Trifolium 18 1 04/20/07 1.12 22.3 0.37 23.7 0.13 23.939426,39628 TR18WATSE Trifolium 18 2 04/20/07 1.10 22.4 0.56 24.1 0.091 24.239429,39625 TR20WATSE Trifolium 20 1 04/20/07 0.74 3.70 1.34 5.78 0.075 5.8539430,39626 TR20WATSE Trifolium 20 2 04/20/07 0.77 3.78 1.40 5.95 0.077 6.0339419,39632 ZSPLWATSE Z Spill 1 04/23/07 0.51 2.56 0.17 3.23 0.039 3.2739420,39633 ZSPLWATSE Z Spill 2 04/23/07 0.56 2.43 0.17 3.15 0.038 3.19

1Calculated dissolved [Se04]-2 = measured ([Se04]-2 + [Se03]-2) - measured [Se03]-2.2Calculated dissolved Organic Se = measured total dissolved Se - measured ([Se04]-2 + [Se03]-2). 3Measured particulate Se = μg of Se in filtered particulates divided by volume of site water filtered.4Calculated total Se = measured particulate Se + measured total dissolved Se.
8 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

Table 4. Total suspended solids concentrations in unfiltered Salton Sea irrigation drain water samples, April and July 2007.

[USGS, U.S. Geological Survey; ID, identification; TSS, total suspended solids; mg/L, milligram per liter]

Field ID Drain

April, 2007 July, 2007

USGS ID TSS

(mg/L) USGS ID TSS(mg/L)

BLNDWATSS Blind A 39258 13.0 39790 23.2

BLNDWATSS Blind B 39268 154 39775 471

LKLNWATSS Lack & Linsey Pond 39257 28.7 39774 66.2

NLD1WATSS Niland 1 39262 66.7 39776 252

NLD2WATSS Niland 2 39263 99.2 39777 143

NLD3WATSS Niland 3 39264 204 39778 275

NLD4WATSS Niland 4 39265 110 39779 144

OOOOWATSS O 39316 167 39788 156

PPPPWATSS P 39315 322 39787 157

POEDWATSS Poe Rd 39252 29.1 39766 68.7

PUMCWATSS Pumice 39250 89.7 39789 230

QQQQWATSS Q 39314 142 39786 103

RRRRWATSS R 39313 156 39785 138

SSSSWATSS S 39320 61.8 39784 68.7

SFWHWATSS San Felipe Wash 39249 9.00 39763 16.6

TTTTWATSS T 39321 53.6 39783 78.5

TR01WATSS Trifolium 1 39318 30.8 39771 55.7

TR12WATSS Trifolium 12 39319 188 39773 369

TR13WATSS Trifolium 13 39255 50.2 39769 100

TR14WATSS Trifolium 14 39256 126 39770 44.2

TR18WATSS Trifolium 18 39251 12.6 39765 50.2

TR19WATSS Trifolium 19 39253 30.3 39767 58.1

FT20WATSS Former Trifolium 20 39247 2.40 39761 21.9

TR20WATSS Trifolium 20 39254 25.6 39768 46.4

TR22WATSS Trifolium 22 39248 89.0 39762 72.5

TR23WATSS Trifolium 23 39259 30.2 39764 66.3

TRSTWATSS Trifolium Storm 39317 25.9 39772 38.5

UUUUWATSS U 39322 83.5 39782 65.3

VLO5WATSS Vail 5 39323 480 39791 26.3

WWWWWATSS W 39267 641 39781 233

ZSPLWATSS Z Spill 39266 25.7 39780 429
Results 9

Table 5. Selenium concentrations in biota samples collected from Salton Sea irrigation drains, 

April 2007.—Continued 

[USGS, U.S. Geological Survey; ID, identification; μg/g, microgram per gram; ---, no data]

USGS ID Field ID Matrix Drain

Moisture Selenium

(percent) (μg/g dry weight)

39548 OOOOALGTSE08A algae O 68.3 1.99

39549 OOOOALGTSE08B algae O 67.3 1.67

39550 OOOOALGTSE08C algae O 71.4 1.57

39545 POEDALGTSE08A algae Poe 75.3 1.07

39546 POEDALGTSE08B algae Poe 78.3 1.03

39547 POEDALGTSE08C algae Poe 81.8 0.88

39539 TTTTALGTSE08A algae T 71.6 1.97

39540 TTTTALGTSE08B algae T 69.6 2.63

39541 TTTTALGTSE08C algae T 68.9 2.50

39551 TR14ALGTSE08A algae Trifolium 14 75.7 2.40

39552 TR14ALGTSE08B algae Trifolium 14 73.2 2.19

39553 TR14ALGTSE08C algae Trifolium 14 72.7 2.48

39557 TR18ALGTSE08A algae Trifolium 18 81.9 5.63

39558 TR18ALGTSE08B algae Trifolium 18 82.4 5.74

39559 TR18ALGTSE08C algae Trifolium 18 83.4 5.41

39542 TR20ALGTSE08A algae Trifolium 20 78.2 1.33

39543 TR20ALGTSE08B algae Trifolium 20 60.6 2.01

39544 TR20ALGTSE08C algae Trifolium 20 63.5 1.75

39554 ZSPLALGTSE08A algae Z Spill 64.3 1.56

39555 ZSPLALGTSE08B algae Z Spill 70.1 1.53

39556 ZSPLALGTSE08C algae Z Spill 69.7 1.45

39611 OOOONPTSE08A plankton O --- 1.97

39612 OOOONPTSE08B plankton O --- 2.05

39613 OOOONPTSE08C plankton O --- 2.29

39608 POEDNPTSE08A plankton Poe --- 1.45

39609 POEDNPTSE08B plankton Poe --- 2.04

39610 POEDNPTSE08C plankton Poe --- 2.08

39602 TTTTNPTSE08A plankton T --- 4.80

39603 TTTTNPTSE08B plankton T --- 1.52

39604 TTTTNPTSE08C plankton T --- 1.40

39614 TR14NPTSE08A plankton Trifolium 14 --- 4.27

39615 TR14NPTSE08B plankton Trifolium 14 --- 4.32

39616 TR14NPTSE08C plankton Trifolium 14 --- 4.41

39620 TR18NPTSE08A plankton Trifolium 18 --- 15.5

39621 TR18NPTSE08B plankton Trifolium 18 --- 17.0

39622 TR18NPTSE08C plankton Trifolium 18 --- 11.9

39605 TR20NPTSE08A plankton Trifolium 20 --- 3.34

39606 TR20NPTSE08B plankton Trifolium 20 --- 2.55
10 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

Table 5. Selenium concentrations in biota samples collected from Salton Sea irrigation drains, 

April 2007.—Continued 

[USGS, U.S. Geological Survey; ID, identification; μg/g, microgram per gram; ---, no data]

USGS ID Field ID Matrix Drain

Moisture Selenium

(percent) (μg/g dry weight)

39607 TR20NPTSE08C plankton Trifolium 20 --- 2.41

39617 ZSPLNPTSE08A plankton Z Spill --- 2.08

39618 ZSPLNPTSE08B plankton Z Spill --- 2.75

39619 ZSPLNPTSE08C plankton Z Spill --- 3.41

39569 OOOOCHITSE08A midge O 81.8 4.36

39570 OOOOCHITSE08B midge O 82.2 3.76

39571 OOOOCHITSE08C midge O 83.1 4.79

39566 POEDCHITSE08A midge Poe 75.8 4.76

39567 POEDCHITSE08B midge Poe 71.3 3.69

39568 POEDCHITSE08C midge Poe 74.6 4.53

39560 TTTTCHITSE08A midge T 83.8 5.39

39561 TTTTCHITSE08B midge T 83.8 4.58

39562 TTTTCHITSE08C midge T 83.9 5.21

39572 TR14CHITSE08A midge Trifolium 14 82.7 7.42

39573 TR14CHITSE08B midge Trifolium 14 80.8 6.86

39574 TR14CHITSE08C midge Trifolium 14 82.5 7.25

39578 TR18CHITSE08A midge Trifolium 18 84.1 12.7

39579 TR18CHITSE08B midge Trifolium 18 87.9 13.4

39580 TR18CHITSE08C midge Trifolium 18 87.0 13.2

39563 TR20CHITSE08A midge Trifolium 20 84.4 9.29

39564 TR20CHITSE08B midge Trifolium 20 84.3 8.52

39565 TR20CHITSE08C midge Trifolium 20 84.0 8.29

39575 ZSPLCHITSE08A midge Z Spill 78.6 3.56

39576 ZSPLCHITSE08B midge Z Spill 81.9 3.18

39577 ZSPLCHITSE08C midge Z Spill 81.6 3.43

39519 OOOOGMBTSE08A mosquitofish O 76.8 5.66

39520 OOOOGMBTSE08B mosquitofish O 77.0 5.53

39521 OOOOGMBTSE08C mosquitofish O 76.9 5.70

39522 OOOOSLMTSE08A sailfin molly O 76.4 3.85

39513 POEDGMBTSE08A mosquitofish Poe 76.7 8.35

39514 POEDGMBTSE08B mosquitofish Poe 76.6 8.78

39515 POEDGMBTSE08C mosquitofish Poe 77.7 9.49

39516 POEDSLMTSE08A sailfin molly Poe 80.4 10.3

39517 POEDSLMTSE08B sailfin molly Poe 79.8 9.71

39518 POEDSLMTSE08C sailfin molly Poe 79.6 9.73

39503 TTTTGMBTSE08A mosquitofish T 76.9 4.78

39504 TTTTGMBTSE08B mosquitofish T 76.2 4.62
Results 11

Table 5. Selenium concentrations in biota samples collected from Salton Sea irrigation drains, 

April 2007.—Continued 

[USGS, U.S. Geological Survey; ID, identification; μg/g, microgram per gram; ---, no data]

USGS ID Field ID Matrix Drain

Moisture Selenium

(percent) (μg/g dry weight)

39505 TTTTGMBTSE08C mosquitofish T 79.1 4.69

39506 TTTTSLMTSE08A sailfin molly T 71.7 4.72

39507 TTTTSLMTSE08B sailfin molly T 72.4 4.65

39523 TR14GMBTSE08A mosquitofish Trifolium 14 76.6 5.57

39524 TR14GMBTSE08B mosquitofish Trifolium 14 77.0 5.50

39525 TR14GMBTSE08C mosquitofish Trifolium 14 78.5 5.66

39526 TR14SLMTSE08A sailfin molly Trifolium 14 74.8 4.23

39527 TR14SLMTSE08B sailfin molly Trifolium 14 75.8 4.29

39528 TR14SLMTSE08C sailfin molly Trifolium 14 75.9 4.51

39535 TR18GMBTSE08C mosquitofish Trifolium 18 76.8 20.2

39536 TR18SLMTSE08A sailfin molly Trifolium 18 75.4 13.8

39537 TR18SLMTSE08B sailfin molly Trifolium 18 75.1 13.8

39538 TR18SLMTSE08C sailfin molly Trifolium 18 74.8 12.8

39508 TR20GMBTSE08A mosquitofish Trifolium 20 74.0 5.97

39509 TR20GMBTSE08B mosquitofish Trifolium 20 74.2 6.21

39510 TR20GMBTSE08C mosquitofish Trifolium 20 74.0 5.90

39511 TR20SLMTSE08A sailfin molly Trifolium 20 73.3 5.38

39512 TR20SLMTSE08B sailfin molly Trifolium 20 71.9 4.86

39529 ZSPLGMBTSE08A mosquitofish Z Spill 77.6 5.38

39530 ZSPLGMBTSE08B mosquitofish Z Spill 77.1 5.71

39531 ZSPLSLMTSE08A sailfin molly Z Spill 77.3 5.03

39532 ZSPLSLMTSE08B sailfin molly Z Spill 75.2 4.74
12 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

Detritus and Sediment: Percent moisture and selenium 

concentrations (μg/g dry weight) in detritus and sediment are 

presented in table 6. Selenium in detritus ranged from 2.64 

to 28.9 and in sediment from 0.15 to 7.02. The particle size 

analyses of sediments, expressed as percent sand, silt, and 

clay, are presented in table 7. Percent TOC in sediments is 

given in table 8 and ranged from 0.3 to 3.6. 

Quality Control Results

Calibration Verification: During the selenium determinations, a calibration verification solution (Spex Claritas PPT®; 

Cat No. CLSe2-2Y) was analyzed at the beginning and end of 

each analytical run. Calibration was considered acceptable if 

the check solution was within plus or minus 10 percent of the 

actual concentration (3 μg/L), which was achieved during all 

analyses.

Reference Materials: Recoveries of selenium from 

QC Plus + Trace Metals Quality Control Standard [n=8 (8 

samples)] and National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1640 Trace 

Elements in Natural Water (n=7) ranged from 91 to 106 percent. Recoveries of selenium from NIST SRM 2704 Buffalo 

River sediment (n=1) and National Research Council Canada 

(NRCC) SRM PACS-1 marine sediment (n=1) were 99 and 

100 percent. The International Atomic Energy Agency (IAEA) 

copepod reference material MA-A-1 (n= 4) and the Institute 

for Reference Materials and Measurements Certified Reference Material (CRM) 414 Trace Elements in Plankton (n=4) 

all exhibited selenium recoveries of 100 percent. Recoveries of 

selenium in NRCC CRM DORM-2 dogfish muscle (n=1) and 

IAEA CRM 407 whole-body fish (n=1) were 100 and 92 percent. Recoveries of TSS from a TSS reference solution (Environmental Resource Associates Hardness Wastewater Standard 

507; n=5) were 100 percent. Recoveries of total carbon from a 

carbon reference material (n=9) ranged from 89 to 158 percent 

and averaged 101 percent; recoveries of total inorganic carbon 

from calcium carbonate (n=13) ranged from 59 to 97 percent 

and averaged 90 percent. 

Analytical and Method Precision: Instrumental precision for selenium as determined by repeated analysis of a 

standard throughout the run for each block (n=14) was less 

than 7 percent relative standard deviation (RSD). Relative 

percent differences (RPDs) between field duplicates (n=74) of 

unfiltered and filtered water samples analyzed for selenium or 

selenium species were mostly ≤(less than or equal) 10, but 5 

duplicates exhibited greater RPDs of 21, 21, 22, 37, and 72. 

Field duplicates of fish (n=4) produced RPDs ranging from 1.4 

to 10, and field duplicates of filtered particulates ranged from 

2.0 to 38 RPD. Relative standard deviations for triplicate field 

samples of detritus (n=7), algae (n=7), plankton (n=7), midge 

larvae (n=7), and whole-body fish (n=9) analyzed for selenium 

were as follows: algae, 3.0 to 20 percent; plankton, 1.6 to 75 

percent; detritus, 1.3 to 33 percent; midge larvae, 2.8 to 13 

percent; and whole-body fish, 1.4 to 6.8 percent. Laboratory 

method precision for triplicate (n=20) preparation and analysis 

of samples for selenium were <7 percent RSD, except for two 

triplicates that were 14 and 29 percent. Method duplicates 

of detritus analyzed for selenium had RPDs of 1.1 and 5.0 

percent. Duplicate analysis of water samples for TSS (n=8) 

resulted in RPDs ranging from 0.3 to 44 percent, whereas 

triplicate analysis for TSS (n=4) resulted in RSDs <8 percent. 

Duplicate analyses of sediments (n=3) for PSA resulted in 

RPDs ranging from 0.9 to 13 percent, and triplicate analyses 

of sediments (n=2) and a sediment control material for PSA 

resulted in RSDs ≤13 percent for the fractions. Duplicate 

analyses of sediments (n=6) for TOC resulted in RPDs ranging 

from 8.6 to 44 percent; triplicate analyses of sediments (n=2) 

resulted in RSDs of 18 and 46 percent.

Spikes: Recoveries of selenium [Se+4, selenate (Se+6), or 

selenomethionine] spiked into filter blanks (n=2) and water 

samples (n=22) ranged from 91 to 114 percent and averaged 

102 percent. Recoveries of selenium spiked into blanks (n=6), 

sediment (n=4), detritus (n=4), and biota (n=14) ranged from 

77 to 134 percent, and averaged 106 percent. Recoveries of 

selenium spikes added to water during analysis (n=19) ranged 

from 101 to 109 percent, and averaged 106 percent; analysis 

spikes of sediment (n=4), filtered particulates (n=2), detritus 

(n=2), and biota (n=11) ranged from 99 to 106 percent, and 

averaged 102 percent. 

Blank Equivalent Concentrations: Blank equivalent 

concentrations (BECs) were computed for selenium for each 

matrix and for TSS blanks analyzed with each set of drain 

water samples. All BECs were less than or equal to their 

respective method detection limits. One TSS BEC was above 

the method detection limit (1.5 mg/L TSS compared to 1.0 

mg/L TSS method detection limit). TSS sample data were corrected for procedural blanks, whereas total selenium sample 

data were not blank corrected.

Instrument Detection, Method Detection, and Method 

Quantitation Limits: The FIHGAAS instrument detection 

limit for selenium was 0.02 μg/L, and for TSS was 0.10 mg/L. 

Method detection limits (MDL) for each matrix for selenium 

were computed as:

3(SDb

2

 + SD

s

2

)

1/2 (3)

where 

SDb is standard deviation of a blank (n=3); and 

SD

s is standard deviation of a low level sample or 

spiked sample (n=3).

The results were water, 0.03 to 1.63 μg/L; filtered particulates, 0.002 μg/L; sediment, 0.015 μg/g dry weight; algae, 

0.018 μg/g dry weight; midge larvae, 0.057 μg/g dry weight; 

plankton, 0.012 μg/g dry weight; detritus, 0.033 μg/g dry 

weight; and whole-body fish, 0.037 μg/g dry weight. Method 

quantitation limits (MQLs) for each matrix were calculated as 

3.3 x MDLs. Method detection limits for TSS were 2.1 and 1.1 

mg/L and MQLs were 7.0 and 3.2 mg/L. All quality control 
Quality Control Results 13

Table 6. Selenium concentrations in detritus and sediment samples collected from Salton Sea irrigation 

drains, April 2007.—Continued

[USGS, U.S. Geological Survey; ID, identification; μg/g, micrograms per gram]

USGS ID Field ID Matrix Drain

Moisture Selenium

(percent) (μg/g dry weight)

39590 OOOODETTSE08A detritus O 78.0 4.86

39591 OOOODETTSE08B detritus O 79.4 9.27

39592 OOOODETTSE08C detritus O 76.2 9.43

39587 POEDDETTSE08A detritus Poe 66.8 11.7

39588 POEDDETTSE08B detritus Poe 67.7 8.4

39589 POEDDETTSE08C detritus Poe 69.6 11.1

39581 TTTTDETTSE08A detritus T 77.1 2.71

39582 TTTTDETTSE08B detritus T 77.2 2.64

39583 TTTTDETTSE08C detritus T 76.4 2.66

39593 TR14DETTSE08A detritus Trifolium 14 77.7 6.98

39594 TR14DETTSE08B detritus Trifolium 14 77.3 6.41

39595 TR14DETTSE08C detritus Trifolium 14 79.9 6.55

39599 TR18DETTSE08A detritus Trifolium 18 79.8 26.5

39600 TR18DETTSE08B detritus Trifolium 18 81.2 23.6

39601 TR18DETTSE08C detritus Trifolium 18 81.9 28.9

39584 TR20DETTSE08A detritus Trifolium 20 74.4 9.42

39585 TR20DETTSE08B detritus Trifolium 20 77.5 7.87

39586 TR20DETTSE08C detritus Trifolium 20 75.0 7.41

39596 ZSPLDETTSE08A detritus Z Spill 80.4 5.40

39597 ZSPLDETTSE08B detritus Z Spill 81.6 4.29

39598 ZSPLDETTSE08C detritus Z Spill 81.2 3.16

39284 BLNDSDTSE08 sediment Blind 55.0 2.02

39338 BLNDSDTSE08B sediment Blind 48.8 1.04

39285 LKLNSDTSE08 sediment Lack and Lindsay 51.1 1.58

39269 NLD1SDTSE08 sediment Niland 1 53.6 1.14

39270 NLD2SDTSE08 sediment Niland 2 52.7 1.15

39271 NLD3SDTSE08 sediment Niland 3 50.4 0.76

39272 NLD4SDTSE08 sediment Niland 4 51.4 1.24

39342 OOOOSDTSE08 sediment O 48.2 0.87

39343 PPPPSDTSE08 sediment P 50.0 1.05

39260 POEDSDTSE08 sediment Poe 32.5 0.57

39283 PUMCSDTSE08 sediment Pumice 47.4 1.03

39344 QQQQSDTSE08 sediment Q 48.3 1.17

39345 RRRRSDTSE08 sediment R 26.1 0.38

39336 SSSSSDTSE08 sediment S 49.2 0.89

39275 SFWHSDTSE08 sediment San Felipe Wash 31.4 0.61

39337 TTTTSDTSE08 sediment T 50.4 0.79
14 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

Table 6. Selenium concentrations in detritus and sediment samples collected from Salton Sea irrigation 

drains, April 2007.—Continued

[USGS, U.S. Geological Survey; ID, identification; μg/g, micrograms per gram]

USGS ID Field ID Matrix Drain

Moisture Selenium

(percent) (μg/g dry weight)

39339 TR01SDTSE08 sediment Trifolium 1 47.6 1.15

39341 TR12SDTSE08 sediment Trifolium 12 23.2 0.23

39282 TR13SDTSE08 sediment Trifolium 13 55.1 1.82

39281 TR14SDTSE08 sediment Trifolium 14 39.5 1.33

39280 TR18SDTSE08 sediment Trifolium 18 55.3 7.02

39279 TR19SDTSE08 sediment Trifolium 19 31.1 0.65

39277 FT20SDTSE08 sediment Former Trifolium 20 23.4 0.15

39278 TR20SDTSE08 sediment Trifolium 20 60.7 2.03

39276 TR22SDTSE08 sediment Trifolium 22 57.5 1.42

39274 TR23SDTSE08 sediment Trifolium 23 48.0 1.23

39340 TRSTSDTSE08 sediment Trifolium Storm 37.5 0.51

39287 UUUUSDTSE08 sediment U 58.2 1.25

39346 VL05SDTSE08 sediment Vail 5 75.8 6.04

39286 WWWWSDTSE08 sediment W 44.8 0.62

39273 ZSPLSDTSE08 sediment Z Spill 60.3 1.42
Quality Control Results 15

Table 7. Particle size distributions in sediment samples collected from Salton Sea irrigation drains, April 2007.

[USGS, U.S. Geological Survey; ID, identification; >, greater than; mm, millimeter]

USGS ID Field ID Drain

Particle size category

> 2 mm

(percent)

Sand

(percent)

Silt

(percent)

Clay

(percent)

39303 BLNDSDTOC08 Blind A 3.71 44.5 34.8 17.0

39328 BLNDSDTOC08B Blind B 0.39 17.5 40.2 41.9

39304 LKLNSDTOC08 Lack & Linsey Pond 13.7 46.9 29.2 10.2

39288 NLD1SDTOC08 Niland 1 0.59 9.29 39.4 50.7

39289 NLD2SDTOC08 Niland 2 0.55 12.9 43.2 43.4

39290 NLD3SDTOC08 Niland 3 1.71 12.1 32.2 53.9

39291 NLD4SDTOC08 Niland 4 0.59 21.3 24.7 53.5

39332 OOOOSDTOC08 O 0.08 21.3 35.2 43.4

39333 PPPPSDTOC08 P 0.59 19.1 37.0 43.3

39261 POEDSDTOC08 Poe Rd 1.29 63.4 19.0 16.3

39302 PUMCSDTOC08 Pumice 2.89 21.8 43.3 32.0

39334 QQQQSDTOC08 Q 0.11 11.5 36.2 52.3

39335 RRRRSDTOC08 R 4.55 54.0 17.4 24.2

39326 SSSSSDTOC08 S 15.4 24.4 30.2 30.0

39294 SFWHSDTOC08 San Felipe Wash 0.57 68.5 18.1 12.8

39327 TTTTSDTOC08 T 0.40 32.3 29.0 38.2

39329 TR01SDTOC08 Trifolium 1 0.12 27.1 32.5 40.3

39331 TR12SDTOC08 Trifolium 12 0.03 58.2 26.9 14.9

39301 TR13SDTOC08 Trifolium 13 5.56 41.5 34.4 18.6

39300 TR14SDTOC08 Trifolium 14 3.27 29.7 37.2 29.9

39299 TR18SDTOC08 Trifolium 18 0.30 64.7 28.3 6.68

39298 TR19SDTOC08 Trifolium 19 1.24 63.9 22.3 12.5

39296 FT20SDTOC08 Former Trifolium 20 0.02 78.3 11.0 10.7

39297 TR20SDTOC08 Trifolium 20 0.74 32.1 42.2 24.9

39295 TR22SDTOC08 Trifolium 22 3.42 33.2 41.1 22.3

39293 TR23SDTOC08 Trifolium 23 18.0 40.8 22.7 18.5

39330 TRSTSDTOC08 Trifolium Storm 0.02 53.0 26.5 20.5

39324 UUUUSDTOC08 U 2.94 15.3 31.5 50.3

39325 VL05SDTOC08 Vail 5 0.42 39.2 53.1 7.23

39305 WWWWSDTOC08 W 0.86 13.7 42.6 42.9

39292 ZSPLSDTOC08 Z Spill 1.58 34.3 39.6 24.5
16 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

Table 8. Percent total organic carbon in sediment samples collected from Salton Sea 

irrigation drains, April 2007. 

[USGS, U.S. Geological Survey; ID, identification]

USGS ID Field ID Drain Total organic carbon 

(percent)

39303 BLNDSDTOC08 Blind 2.1

39328 BLNDSDTOC08 B Blind B 1.0

39304 LKLNSDTOC08 Lack & Linsey Pond 3.3

39288 NLD1SDTOCO8 Niland 1 1.5

39289 NLD2SDTOC08 Niland 2 1.3

39290 NLD3SDTOC08 Niland 3 0.8

39291 NLD4SDTOC08 Niland 4 3.5

39332 OOOOSDTOC08 O 0.6

39333 PPPPSDTOC08 P 2.3

39261 POEDSDTOC08 Poe 1.0

39302 PUMCSDTOC08 Pumice 1.5

39334 QQQQSDTOC08 Q 0.6

39335 RRRRSDTOC08 R 0.5

39326 SSSSSDTOC08 S 1.9

39294 SFWHSDTOC08 San Felipe Wash 0.7

39327 TTTTSDTOC08 T 0.8

39329 TR01SDTOCO8 Trifolium 1 1.4

39331 TR12SDTOC08 Trifolium 12 0.3

39301 TR13SDTOC08 Trifolium 13 3.0

39300 TR14SDTOC08 Trifolium 14 1.4

39299 TR18SDTOC08 Trifolium 18 2.1

39298 TR19SDTOC08 Trifolium 19 1.0

39296 FT20SDTOC08 Former Trifolium 20 0.5

39297 TR20SDTOC08 Trifolium 20 2.0

39295 TR22SDTOC08 Trifolium 22 2.5

39293 TR23SDTOCO8 Trifolium 23 3.2

39330 TRSTSDTOC08 Trifolium Storm 0.6

39324 UUUUUSDTOC08 U 1.5

39325 VL05SDTOC08 Vail 5 3.6

39305 WWWWSDTOC08 W 0.8

39292 ZSPLSDTOC08 Z Spill 1.9
References Cited 17

results for the study were within acceptable limits as specified 

by USGS-CERC.

References Cited

American Public Health Association, 1998, Standard methods 

for the examination of water and wastewater (20th ed.), 

Method 2540: Washington, D.C., American Public Health 

Association, p. 257–258.

Universal Instruments Corporation, 1999, Operating manual 

for Model CM 5014 Coulometer.

American Society of Testing and Materials, 2003, Standard 

test method for particle-size analysis of soils, D422–63 

(2002), in Annual Book of ASTM Standards, v. 04.08: 

West Conshohocken, Pa., American Society for Testing and 

Materials, p. 10–17. 

Cutter, G.A., and Bruland, K.W., 1984, The marine biogeochemistry of selenium—a re-evaluation: Limnology and 

Oceanography, v. 29, no. 6, p. 1,179–1,192.
18 Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007

Publishing support provided by: 

Rolla Publishing Service Center 

For more information concerning this publication, contact:

Director, USGS Columbia Environmental Research Center

4200 New Haven Road

Columbia, MO 65201

(573) 875–5399

Or visit the Columbia Environmental Research Center Web site at:

http://www.cerc.usgs.gov
References Cited 19
May and others—Total Selenium and Selenium Species in Irrigation Drain Inflows to the Salton Sea, California, April and July 2007—OFR 2007–1347

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