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Technical Report Series 

The Biological Resources Division publishes scientific and technical articles and reports resulting from the research performed by 

our scientists and partners. These articles appear in professional journals around the world. Reports are published in two report 

series: Biological Science Reports and Information and Technology Reports. 

Series Descriptions 

Biological Science Reports ISSN 1081-292X 

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include extensive data or theoretical analyses. Papers in this 

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Cover photographs: 

Information and Technology Reports ISSN 1081-2911 

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Top: The ASARCO facility in Omaha Nebraska, on the bank of the Missouri River, lies mostly between the 

Burt-Izard Drain to the north (bottom right of the picture) and Interstate 80 to the south. Photo taken 

April 1992 by Aerpic-Camera, Omaha, NE 68104. 

Right: Sediment porewater extraction on site on the Missouri River in a USGS boat. 

Photo by John Delashmit, USEPA 

Bottom: Porewater extraction during the night. Extraction was completed within 12 hours of field collection of 

sediment. Photo by Steve Olson, USGS Columbia Environmental Research Center 

Center: Adult female Ceriodaphnia dubia, the toxicity test organism used in this study. 

Photo by Robin Calfee, USGS Columbia Environmental Research Center. 

Left: May 2001 photo of the ASARCO site, showing ongoing conversion to a city park. Aerpic-Camera, 

Omaha, NE 68104. 

Copies of this publication are available from the National Technical Information Service, 5285 Port Royal Road, 

Springfield, Virginia 22161 (1-800-553-6847 or 703-487-4650). Copies also are available to registered users 

from the Defense Technical Information Center, Attn.: Help Desk, 8725 Kingman Road, Suite 0944, Fort 

Belvoir, Virginia 22060-6218 (1-800-225-3842 or 703-767-9050). 

An electronic version of this report is available on-line at: http://www.cerc.usgs.gov/pubs/center/pdfdocs/BSR2001-0004.pdf 

Printed on recycled stock 
Toxicity and Bioavailability of 

Metals in the Missouri River 

Adjacent to a Lead Refinery 

Biological Science Report 

USGS/BRD/BSR—2001-0004 

December 2001 

By

Duane C. Chapman

Ann L. Allert

James F. Fairchild

Thomas W. May

Christopher J. Schmitt

and

Edward V. Callahan

U.S. Department of the Interior


U.S. Geological Survey


Columbia Environmental Research Center


Columbia, Missouri 65201

. 

This report was completed under Interagency Agreement DW-14952122-01-1 between the U.S. Geological Survey 

and the U.S. Environmental Protection Agency Region VII (RCRA). 

Suggested citation: 

Chapman,D.C., A.L. Allert, J.F. Fairchild, T.W. May, C.J. Schmitt, and E.V. Callahan. 2001. Toxicity and 

bioavailability of metals in the Missouri River adjacent to a lead refinery. U.S. Geological Survey Biological 

Science Report USGS/BRD/BSR—2001-0004. 27 p. 
Contents 

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

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

Methods ............................................................................................................................................................................2

Results and Discussion....................................................................................................................................................7

Conclusions.....................................................................................................................................................................25

Acknowledgements ........................................................................................................................................................26

Literature Cited ................................................................................................................................................................26

Figures 

1. Location of sediment sampling sites ......................................................................................................................3

2. Comparison between study sites of the first sediment principal component................................................23

3. Results of hierarchical cluster analysis of element concentrations measured from sediment samples .....23

4. Results of hierarchical cluster analysis of element concentrations measured from aqueous samples ......24

5. Biplot of element concentration data measured fromsediment samples........................................................24

6. Biplot of element concentration data measured fromwater samples ..............................................................24

Tables 

1. Comparison of historical river water chemistry, CERC well water, and reconstituted river water................5

2. Comparison of field water quality measurements with measurements made at CERC....................................8

3. Water quality measurements taken before start of Ceriodaphnia toxicity test..............................................9

4. Grain size analysis of sediments .............................................................................................................................9

5. Concentrations of arsenic, cadmium, lead and zinc in sediment samples.......................................................10

6. Concentrations of arsenic, cadmium, lead and zinc in aqueous samples .......................................................11

7. Concentrations of elements in sediment determined by semiquantitative ICP-MS scan.............................12

8. Concentrations of elements in water determined by semiquantitative ICP-MS scan ...................................14

9. USEPA Water Quality Criteria for selected trace metals ...................................................................................16

10. Calculated USEPA Water Quality Criteria Values for selected metals ............................................................16

11. Concentrations of simultaneously extracted metals in sediments...................................................................17

12. Molar concentrations of acid-volatile sulfide and simultaneously extracted metals in sediments.............17

13. Calculated Toxic Units derived from estimated porewater concentrations....................................................18

14. Calculated Toxic Units derived from measured porewater metal concentrations..........................................19

15. Survival of Ceriodaphnia dubia exposed to sample and control water in a 7-day toxicity test.................19

16. Reproductive output of Ceriodaphnia dubia in a toxicity test.......................................................................20

17. Correlation of element concentrations in sediment samples with principal components ............................22

18. Correlation of element concentrations in water samples with principal components...................................22

19. Historical water quality of monitoring well 19 and water quality of the well during this study..................26

iii

Toxicity and Bioavailability of Metals


in the Missouri River


Adjacent to a Lead Refinery


by 

Duane C. Chapman 

Ann L. Allert 

James F. Fairchild 

Thomas W. May 

Christopher J. Schmitt 

U.S. Geological Survey

Columbia Environmental Research Center

4200 New Haven Road

Columbia, MO 65201

and 

Edward V. Callahan 

Environmental Statistics 

S2830 Kamrowski Rd 

Fountain City, WI 54629 

Abstract. This study is an evaluation of the potential environmental impacts of contaminated 

groundwater from the ASARCO metals refining facility adjacent to the Missouri River in 

Omaha, Nebraska. Surface waters, sediments, and sediment pore waters were collected from 

the Burt-Izard drain, which transects the facility, and from the Missouri River adjacent to the 

facility. Groundwater was also collected from the facility. Waters and sediments were 

analyzed for inorganic contaminants, and the toxicity of the waters was evaluated with the 

Ceriodaphnia dubia 7-day test. Concentrations of several elemental contaminants were 

highly elevated in the groundwater, but not in river sediment pore waters. Lead 

concentrations were moderately elevated in whole sediment at one site, but lead 

concentrations in pore waters were low due to apparent sequestration by acid-volatile sulfides. 

The groundwater sample was highly toxic to C. dubia, causing 100% mortality. Even at the 

lowest groundwater concentration tested (6.25%) C. dubia survival was reduced; however, at 

that concentration, reproduction was not significantly different from upstream porewater 

reference samples. Sediment pore waters were not toxic, except reproduction in pore water 

collected from one downstream site was somewhat reduced. The decrease in reproduction 

could not be attributed to measured elemental contaminants. 

Key words: Acid-volatile sulfides, arsenic, ASARCO, AVS, brownfields, cadmium, Omaha City 

(Neb.), sediment pore water, SEM 
2 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Introduction 

The American Smelting and Refining Company 

(ASARCO) Omaha facility, located at 500 Douglas 

Street in Omaha, Nebraska, was a primary lead refinery 

designed and operated to process lead bullion 

containing recoverable amounts of several different 

metals. Refinement was achieved using traditional 

pyro-metallurgical processes including addition of 

metallic and non-metallic compounds to molten lead to 

remove imp urities. The Omaha plant produced refined 

lead and specialty metal by-products including 

antimony-rich lead, bismuth, dore (silver-rich material) 

and antimony oxide. The 23-acre facility, which lies 

along the Missouri River, was closed in July 1997. 

Remediation at the facility is being addressed under 

the state Remedial Action Plan Monitoring Act 

(RAPMA), a voluntary remediation program. 

Numerous buildings and structures remain on the site. 

The approved remediation plan calls for complete 

demolition of all site structures, regrading, and 

capping of the site. 

Previous characterization and remedial design 

documents submitted by ASARCO on behalf of the 

Omaha plant have failed to clearly define the level of 

threat that previous releases and contaminated 

groundwater underlying the facility poses to biota 

living in the adjacent Missouri River. The potential 

threat stems from elevated levels of arsenic, lead, and 

other metals in the groundwater. Groundwater 

elevation data indicate that most of the underlying 

contaminated groundwater moves into the Missouri 

River. Lead concentrations in water surface grab 

samples collected periodically by ASARCO’s 

contractor (Hydrometrics, Inc.) were sometimes higher 

than those collected immediately upstream from the 

site. In March 1997, ASARCO collected surface water 

and sediment samples from the Missouri River and a 

small on-site tributary (known as the Burt-Izard sewer 

outfall) and obtained analytical results. Elevated 

levels of inorganic contaminants in some river 

sediments have also been reported by Hydrometrics, 

Inc. Subsequent to this activity the Nebraska 

Department of Environmental Quality (NDEQ) made a 

final decision on the remedial plan for this site. The 

remedial plan does not specifically address 

groundwater or river sediments. The U.S. 

Environmental Protection Agency (USEPA) felt that 

further investigation of the elevated metal levels in the 

river sediments near the ASARCO refinery was 

warranted. 

The USEPA entered into an agreement with the 

US Geological Survey, Biological Resources Division, 

Columbia Environmental Research Center (CERC) to 

perform this investigation. Specific objectives of this 

study were to determine the concentration, 

bioavailability, and toxicity of metals in the Missouri 

River adjacent to the site. In this report we present 

and discuss the findings of this investigation. 

Methods 

Porewater toxicity testing 

A porewater approach was undertaken to 

determine the bioavailability and toxicity of metals at 

the site. For many inorganic contaminants, ecological 

risk is associated with the free metal ion concentration 

in water. Pore water is the interstitial water between 

sediment particles. Because of restricted mixing within 

sediments, pore waters are in contact with sediments 

for a long time relative to surface waters. 

Consequently, porewater concentrations of sedimentassociated contaminants are often elevated relative to 

overlying waters, and may represent a worst-case 

scenario in terms of ecological risk to aquatic 

organisms in overlying waters. 

Because contaminants may be associated with 

sediments through a number of different mechanisms, 

not all sediment-associated contaminants are available 

for dissociation into pore waters--i.e., not all are 

equally bioavailable. For inorganic contaminants 

(metals and metalloids), such associations may be very 

loose, such as would be represented by 

electrochemical attraction to the charged surfaces of 

clay mineral particles. These contaminants can be 

dislodged by changes in ionic composition or 

concentration of the surrounding water. On the other 

end of the availability spectrum are those elements of 

concern that may be part of the mineral phase itself. 

The metal sulfides--the ores refined at the ASARCO 

facility-- represent this condition. These metals are 

only released to the liquid phase upon complete 

destruction of the mineral matrix (i.e., by digestion with 

strong acids) and are not generally considered to be 

biologically available (Tessier et al. 1979; Gobas and 

Zhang 1994). Intermediate associations between 

elemental contaminants and sediment particles include 

sorption and other interactions with iron and 

manganese hydroxides; and complexation by sediment 

organic matter, including the humic and fulvic acids. 

The analysis of bulk sediments for total metals 

generally involves the complete digestion of the 

matrix. Consequently, this method may include the 

measurement of metals and other elements that are not 

biologically available, and when used alone may 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 3 

overestimate ecological risk. We therefore also intersect the sediment pore water, which makes 

incorporated a method of dissociation (leaching assessment of pore water highly appropriate for this 

sediments with a weak acid, 1-N HCl) that simulates study. Use of the porewater technique also allows 

relevant biological conditions (DiToro et al. 1992) for testing with the Cladoceran Ceriodaphnia dubia, 

assessing and evaluating the biological availability of which is highly sensitive to metals but not to ammonia. 

sediment-associated contaminants at the ASARCO- The latter is a likely contaminant in urban 

Omaha facility and adjacent areas of the Missouri environments that can confound test results with 

River. We considered this method, which does not ammonia-sensitive organisms. The use of the 

consider those metals bound to acid-volatile sulfides porewater medium also eliminates the problem of grain 

as bioavailable (DiToro et al. 1992), to be the most size preference by the test organisms, which 

appropriate for assessing sediment-associated sometimes confounds whole-sediment toxicity tests. 

contaminants at the ASARCO facility. In addition, 

contaminated ground water seeping into the river from Site selection 

beneath the ASARCO facility would first Figure 1 represents a map of the site and the sampling 

locations. During a site visit in the spring of 1998, 

Figure 1. Location of sediment sampling sites near the ASARCO facility in Omaha, Nebraska. Site 1 is the site 

farthest north. Site 2 is on the eastern bank. Site 4 is within the Burt-Izard Drain, and Site 5 is in the Missouri 

River at the mouth of the Burt-Izard. Site 24 is under the I-480 Bridge and Site 25 is the farthest south. 

Approximate boundary of ASARCO facility is indicated. 
4 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

sandy sediments were found along the ASARCO 

waterfront. It was also determined that there were 

three likely paths of groundwater movement from the 

ASARCO facility into the river: 1) general seepage 

along the waterfront, 2) the Burt-Izard Drain, an open 

ditch running along the northern boundary of the site, 

and 3) the Chicago Street Drain, a now perforated 

storm drain traversing the property at a depth of about 

2 m below the ground surface. Therefore, it was 

determined that sediment would be taken from one site 

within the Burt-Izard Drain (which is an open ditch or 

creek) and one at its confluence with the river. Two 

sites were to be sampled at the mouth of the Chicago 

Street Drain (which is a pipe buried at approximately 4 

m depth). In addition, two sediment samples were to 

be taken just upstream of the ASARCO facility, one on 

the same (west) bank and one just upstream of the 

ASARCO facility on the opposite (east) bank. The 

upstream sediment sites were to function as reference 

sites. Sites along the waterfront of the facility were 

also selected for sediment sampling. At the time of 

sampling nearly all of the sediment had been scoured 

from this outside-bend area. Consequently, sediment 

was collected as planned from the site within the BurtIzard Drain (Site 4) and at its mouth (Site 5), and from 

the reference site across the river (Site 2). However, 

there was no sediment to sample anywhere along the 

ASARCO waterfront. The sandy sediments that had 

been observed there in the spring had been removed 

by subsequent high water. The bottom along this 

outside bend of the Missouri River consisted primarily 

of riprap and slag. A search for an appropriate 

upstream same-side-of-river sediment sample was only 

successful after moving approximately 0.75 kilometers 

upstream. This sample (Site 1) was collected from an 

eddy upstream of the outfall channel for Grace Street 

and North Interceptor. Sediment was found in two 

eddy areas downstream from the plant and these were 

sampled (Site 24 and Site 25). It was decided at the 

time of sampling that sites further downstream would 

be highly complicated by other potential inputs, and 

no further sediment sampling was conducted. 

A sample from one of the monitoring wells near 

the river (MW19) was provided by ASARCO, which 

we analyzed and tested to determine the potential 

toxicity of ground water entering the river. In addition, 

two surface water samples were taken from the 

Missouri River. The river water samples served as 

additional references to verify that C. dubia was in 

fact adaptable to the water quality of the river and to 

verify that no upstream toxic releases occurred on that 

date that might confound the test. 

Field procedures 

Sediment was collected on October 5, 1998. A 

Ponar dredge was used to sample sites over a meter 

deep, which includes all sites except Site 4. A 10-cm 

diameter coring device (Onuf et al. 1996) was used at 

Site 4. A Rockwell� PLGR global positioning system 

was used to record the position of sampling sites. 

Pore water was extracted on site by means of 

pressure filtration using an apparatus similar to that 

described in Carr and Chapman (1995) and retained in 

an acid-washed polyethylene sample bottle. Nitrogen 

gas (analytical grade) was used as the source of 

pressure, and pressure in the extraction devices did 

not exceed 35 psi. Not all porewater extraction was 

completed before leaving the site, but extractions were 

completed within twelve hours of sample collection. 

Between two and three liters of pore water were 

collected at each site. Surface water samples were 

collected by completely submersing the sample bottle, 

opening the lid and filling the bottle, and then 

recapping the bottle underwater. 

Conductivity, pH, and dissolved oxygen were 

measured on each aqueous sample immediately after 

collection. Dissolved oxygen was determined with a 

YSI® model 57 dissolved oxygen meter and 

conductivity was determined using a YSI®

 S-C-T 

meter. Orion® 290A meters with a glass gel electrode 

were used to measure pH. An 100 mL aliquot of each 

aqueous sample (pore, surface, or ground water) was 

filtered with a 0.45 mm polycarbonate filter and 

acidified with 1% ultrapure nitric acid (v:v) for metals 

preservation. Two filtration blanks were also prepared 

using reverse osmosis water and preserved. One of 

these was collected before on-site filtration began and 

the other as the last filtration of the batch. Two 

aliquots of the sediment from which each pore water 

was extracted were also retained for metals analysis. 

All equipment that contacted sediment or sediment 

pore water was acid-washed prior to use. All aqueous 

samples to be used in toxicity tests were centrifuged 

(3000 g for 10 minutes) to remove fines after arrival at 

CERC. All samples, aqueous or solid-phase, were kept 

on ice or refrigerated (T=5°C) until use. 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 5 

Laboratory procedures 

Rearing of test organisms 

Based on data provided by Hydrometrics, Inc, it 

was determined that Missouri River water from the 

Omaha area is usually somewhat higher in potassium, 

sodium and sulfates than the CERC well water in which 

our test organisms are normally reared. Therefore, C. 

dubia were reared at the CERC for more than three 

months prior to the tests in a reconstituted water 

formulated to approximate that of the river. 

Reconstituted river water was made by addition of 180 

mg of K2SO4 and 1980 mg of Na2SO4 to 15L of CERC 

well water. The water chemistry of this reconstituted 

water is given in Table 1. New reconstituted river 

water was made weekly and allowed to mix and aerate 

overnight before use. Culture techniques were similar 

to those described in USEPA (1994). Ceriodaphnia 

were fed a diet of fermented trout chow, yeast, and 

cereal leaves (YTC; USEPA 1994) and algae 

(Selenastrum capricornutum and Ankistrodesmus 

falcatus; 60:40 mix). 

Table 1. Comparison of historical river water 

chemistry, Columbia Environmental Research Center 

(CERC) well water, and reconstituted river water. 

Historical averages of river water chemistry computed 

from unpublished Hydrometrics, Inc. data, and 

supplied to CERC by USEPA. All values in mg/L. 

Historical CERC Reconstituted 

Element average well river water 

Sodium 66.5 23.0 66.0

Potassium 7.9 2.2 7.9

Calcium 67.7 71.0 71.0

Magnesium 25.4 27.0 27.0

Chloride 17.1 21.0 21.0

Bicarbonate 184 188 188

Sulfate 212 47.0 145

Summation 

of identified 580 379 526

salts

Toxicity tests 

Toxicity tests were performed using the C. dubia 

7-day survival and reproduction test (USEPA 1994). 

USEPA (1994) stipulates the use of a dilution series for 

effluent toxicity testing, but not normally for 

environmental samples collected outside the mixing 

zone. We tested a dilution series of the groundwater 

sample (100, 50, 25, 12.5, and 6.25%) to determine the 

degree of toxicity of this water in the C. dubia test. 

We also tested a dilution series (100, 50, and 25%) of 

the pore water collected from within the Burt-Izard 

drain. Reconstituted river water was used as the 

diluent. 

The hardness and alkalinity of surface water 

samples and some porewater samples were higher than 

expected, ranging from 250 mg/L to over 700 mg/L 

hardness as CaCO3. Therefore, another reconstituted 

water, designed to reflect the chemistry of the surface 

waters collected on October 5, was also prepared from 

CERC well water and salts. This “Hard Recon” was 

tested as an additional treatment, to verify that C. 

dubia were tolerant of this very hard, alkaline, highsulfate water. To make this second reconstituted 

water, 236 mg of CaSO4, 34.8 mg of MgSO4, and 129 mg 

NaHCO3 were added per each liter of well water. Well 

water chemistry is described in Table 1. 

A positive control dilution series (i.e., reference 

toxicant) consisting of three concentrations of NaCl in 

CERC well water (2.50, 1.25, and 0.613 parts per 

thousand) was also tested concurrently with the 

toxicity test. Lastly, a procedural control in CERC well 

water was also performed concurrently with the test. 

C. dubia used in the well water control were reared in 

well water instead of reconstituted river water. 

The C. dubia toxicity tests were conducted 

according to USEPA (1994). Animals were exposed to 

15 mL of the sample or the appropriate dilution in 

30-mL glass beakers for seven days. One neonate, 

less than 12 hours old, was added to each beaker at 

the beginning of the test (day 0). There were ten 

replicates of each treatment. Waters were renewed 

daily. Endpoints, recorded daily, were lethality 

(absence of movement) and reproduction (number of 

neonates produced). Temperature in the test beakers 

was maintained at 25± 1°C by means of a temperaturecontrolled water bath. Test organisms were fed 1 mL 

of YTC and 1 mL of algae after renewal. 
6 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Sediment and water quality measurements 

Hardness, alkalinity, dissolved oxygen, pH, 

conductivity, nitrate+nitrite, sulfate, phosphate, 

chloride, calcium, and ammonia concentration of 

aqueous samples were measured after arrival at CERC. 

Hardness, alkalinity, calcium, and chloride were 

determined by titration. Dissolved oxygen was 

determined with a YSI® model 57 dissolved oxygen 

meter and conductivity was determined using a YSI® 

S-C-T meter. Orion® EA 940 meters with glass gel 

electrodes were used to measure pH. The Orion 

EA940 meters with an Orion® Model 95-12 ammonia 

ion selective electrode were employed for ammonia 

determinations. Sulfate, nitrate+nitrite, and phosphate 

concentrations were measured with a Hach® DR 2000 

spectrophotometer. Dissolved organic carbon of 

sediment pore water was measured with a Technicon 

AAII® system. Sediment grain size was determined 

with the Bouyoucous Hydrometer Method. Standard 

operating procedures for these techniques can be 

found in USEPA and USGS (1998). 

Daily during the test, water from exposure beakers 

(post-exposure) was collected for dissolved oxygen, 

pH and conductivity measurements. Hardness, 

alkalinity, and ammonia concentrations were also 

measured in the post-exposure water on day 4 and day 

7. In order to have sufficient volume of post-exposure 

sample, water from all replicates within a treatment was 

composited in a 250-mL beaker for these analyses. 

Sample preparation and analysis 

Water: No further chemical preparation was 

conducted on acidified water samples prior to analysis. 

Samples were first subjected to a semiquantitative 

scan by inductively coupled plasma-mass 

spectrometry (ICP-MS) to indicate concentrations of 

target and other elements of interest, to reveal the 

presence of unexpected elements, to determine optimal 

dilutions for quantitative analysis, and to identify 

samples appropriate for QC purposes in the 

quantitative run. 

The semiquantitative scan is reported to be +30% 

to +50% in accuracy by the manufacturer. In addition, 

all water samples were subjected to an ICP-MS 

quantitative analysis which targeted the main elements 

of interest (Zn, As, Cd, and Pb). In this analysis, Pb 

was monitored and reported as the sum of three 

isotopes (Pb-206 + Pb-207 + Pb-208). Two masses 

were monitored for Zn and Cd, but only one reported 

(Zn-66 and Cd-114). 

Sediment AVS and SEM: For AVS and SEM 

determination, each sediment sample was briefly 

homogenized in its collection container with a plastic 

scoop, following which a ~5 mL aliquant was taken for 

AVS determination. During the AVS determination on 

each sediment sample, a simultaneously extractable 

metals fraction was generated in 1N hydrochloric acid. 

Fifty mL of each extract was vacuum filtered through a 

0.4 mm polycarbonate membrane. A silver/sulfide 

electrode was used for determining AVS (Brumbaugh 

et al. 1994; Brumbaugh and Arms 1996). For 

determination of Zn, As, Cd, and Pb by quantitative 

analysis ICP-MS, a portion of each filtered SEM extract 

(10 mL) was subjected to a microwave oven nitric 

acid/hydrogen peroxide digestion to minimize potential 

interference from Cl- during analysis. Final dilution 

volume for the digestates was 50 mL in a matrix of 2% 

nitric acid. The resulting digestates were analyzed by 

quantitative ICP-MS as described above for water 

(May et al. 1997). 

Sediment Total Recoverable Metals: A portion of 

each sediment sample was lyophilized and then 

homogenized to a coarse powder, following which a 

dried aliquant was digested in a sealed Teflon vessel 

in a microwave oven with nitric acid, hydrochloric acid, 

and hydrogen peroxide to prepare a digestate suitable 

for quantitative and semiquantitative scan by ICP-MS 

as described above for water. Final acid matrix was 5% 

nitric acid and 0.5% HCl. 

Quality Control: Extensive quality control was 

conducted as part of preparation and analysis of 

samples. Where samples were subjected to a 

digestion (i.e., sediment), quality control included 

digestion blanks, sample replicates, spikes, and 

reference materials. Quality control for quantitative 

ICP-MS (all samples) included duplicate analyses, 

dilution checks, reference solutions, analysis spikes, 

an interference check, and calibration checks. For the 

semiquantitative scan, the following quality control 

was included: a calibration check, an analysis spike, 

and a precision check. As part of the quality assurance 

procedures, CERC also analyzed “blind” water and 

sediment samples provided by USEPA. 

Details of preparation and analytical protocols 

and quality control results can be found in CERC 

reports FY-99-32-03 and FY 99-32-04. 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 7 

Statistical analysis 

Survival data were evaluated with logistic analysis 

(Agresti 1990). Analysis of variance with rank 

transformation (Snedecor and Cochran 1989) was used 

to evaluate reproduction data. In the analysis of 

variance, total reproduction for each daphnid over the 

seven-day test (including those that died during the 

experiment) was the dependent variable. 

Experimentwise error rates for all pairwise comparisons 

were controlled at a= 0.05 with Tukey’s method 

(Hochberg and Tamhane 1987). 

The influence of metal concentrations on survival 

and reproduction was assessed with principal 

components analysis (Johnson and Wichern 1992). 

Principal components analysis was performed to find 

relationships between measured water quality and 

metals variables and the toxicity test data. Duplicate 

field water samples were taken at Site 1 and an average 

of the resulting element concentrations was used to 

represent that site. Elements with at least half the 

observations above detection limit were included in 

the analysis. In addition, Br was excluded from the 

sediment database since it had identical 

concentrations at each site where it was measured. 

Detection limit / 2 was used for analysis when a 

concentration was recorded as below detection limit. 

Concentration data from water samples from MW19 

was excluded from analysis since concentrations 

found there were so high in relation to other sites that 

they unduly influenced the entire analysis. 

Concentrations were log transformed prior to analysis 

using the formula log10(x+1). Thirty-nine elements 

from sediment samples were retained for analysis, 

including: Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, 

Eu, Fe, Ga, Gd, Ho, K, La, Li, Mg, Mn, Mo, Na, Nd, Ni, 

Pb, Pr, Rb, Sb, Sm, Sn, Sr, Tb, Ti, V, Y, Yb, Zn, and Zr. 

Thirty-one elements from water samples were retained 

for analysis, including: Al, As, B, Ba, Br, Ca, Cd, Ce, 

Co, Cr, Cu, Fe, Ga, I, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb, 

Sb, Sn, Sr, Ti, U, V, W, and Zn. 

In addition, a hierarchical cluster analysis was 

performed to evaluate similarity between sites in terms 

of elemental composition of water and sediment 

samples (Kaufman and Rousseeuw 1990). 

Results and Discussion 

Site locations 

It was difficult to find sediment near the ASARCO 

facility. During the spring site visit, we had 

determined that we would not sample below the I-480 

bridge, just downstream of the ASARCO facility, 

because there was a large storm drain at that site that 

could confound the results. Because there were no 

sediments directly adjacent to the ASARCO facility, 

we were forced to forego that decision and collect 

sediments at alternate locations. However, it should 

be noted that at the time of sample collection, no water 

was entering the river through these drains, despite 

the heavy rain that had occurred during the previous 

night. These drains are very likely non-functional. 

Sites 2 (reference site across the river), 4 (upstream on 

the Burt-Izard Drain) and 5 (mouth of the Burt-Izard 

Drain) were the only planned sites at which we were 

able to collect sediments. Site1 was moved 

approximately 0.75 kilometers upstream (above the 

confluence of the Grace Street and North Interceptor 

drain). Sites 24 and 25 were added in order to have 

sediments collected downstream of the facility. Site 24 

was collected directly under the I-480 bridge, and Site 

25 was collected from an eddy 150 m downstream of 

the bridge. Figure 1 indicates the locations of the 

revised sediment sampling sites. 

Water quality and sediment description 

Field measurements of dissolved oxygen, 

conductivity and pH and initial measurements of these 

parameters at the laboratory are given in Table 2. 

Dissolved oxygen concentrations of pore water 

and groundwater increased between collection in the 

field and arrival at the lab. The pH values also 

increased slightly. Table 3 contains additional water 

quality measurements measured at CERC that were not 

also measured in the field. 
8 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Table 2. Comparison of dissolved oxygen concentrations, conductivity, and pH measurements performed in the 

field with measurements made at CERC before the start of the toxicity test, including measurements on CERC 

reference waters and on dilutions of sample waters. MW19 is the groundwater sample from monitoring well 19. 

SEDx refers to pore waters collected from the various sediment sites. NaCl refers to the sodium chloride 

reference toxicant treatments and the concentration of NaCl added to reconstituted river water. Hard Recon 

refers to the reconstituted water made to reflect the water quality of the river waters. 

Field Measurements Measurements at CERC 

Dissolved Dissolved 

Oxygen 

(mg/L) 

Cond. 

(m mhos/cm2

) pH 

Oxygen 

(mg/L) 

Cond. 

(m mhos/cm2

) pH 

River water 1 8.3 600 8.83 9.5 600 8.34 

River water 2 9.1 600 8.02 9.7 610 8.33 

SED 1 4.2 690 7.34 10.2 810 7.75 

SED 2 4.6 800 7.62 9.6 790 8.07 

SED 4-100% 3.2 600 7.58 9.4 610 7.92 

SED 4-50% 9.6 575 8.14 

SED 4-25% 9.6 510 8.17 

SED 4-12.5% 9.4 500 8.18 

SED 5 5.8 800 6.99 10.2 1310 7.61 

SED 24 7.9 580 7.58 9.6 710 8.30 

SED 25 5.3 650 7.73 10.2 900 7.88 

MW19-100% 3.8 2980 7.42 10.2 3110 8.25 

MW19-50% 

MW19-25% 

MW19-12.5% 

MW19-6.25% 

NaCl 2.5% 

NaCl 1.25% 

NaCl 0.613% 

Reconstituted 

river water 

Hard Recon 

CERC well 

water 

9.8 1400 7.98 

9.6 1200 8.08 

9.6 850 8.15 

9.6 690 8.16 

8.5 4620 8.19 

8.5 2600 8.19 

8.8 1510 8.19 

8.6 510 8.17 

8.0 580 8.26 

8.6 341 8.48 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 9 

Table 3. Water quality measurements taken before start of Ceriodaphnia toxicity test. MW 19 is the 

groundwater sample from monitoring well 19. SEDx refers to pore waters collected from the various sediment 

sites. NaCl refers to the sodium chloride reference toxicant treatments and the concentration of NaCl added to 

reconstituted river water. Hard Recon refers to the reconstituted water made to reflect the water quality of the 

river waters. Units are mg/L. 

DOC 

Alkal. 

(as 

Hard. 

(as NH3 NO2 + 

CaCO3) CaCO3) (as N) NO3 SO4 PO4 Cl Ca

River water 1 3.3 162 244 0.068 0.52 182 0.109 8.8 71.8 

River water 2 7.9 162 244 0.070 0.50 171 0.133 13.8 79.8 

SED 1 390 416 2.07 0.00 131 0.830 8.8 112 

SED 2 8.2 344 390 0.965 0.29 162 0.149 13.8 112 

SED 4 1.2 160 208 11.2 0.40 120 0.316 13.8 87.9 

SED 5 15.2 776 748 13.5 0.00 103 0.257 8.8 193 

SED 24 4.6 234 336 0.547 0.44 161 0.162 13.8 96.0 

SED 25 6.6 366 410 1.47 0.25 143 0.167 23.9 128 

MW 19 6.5 402 550 1.20 0.15 186 0.806 321 185 

Reconstituted 

river water 250 228 0.0201 0.60 74.0 0.066 8.8 169 

Hard Recon 240 250 0.68 154 0.042 

Well 1.2 246 284 0.027 0.40 63.6 0.060 13.8 39.5 

Table 4 gives the grain size analysis of the 

sediments. Sites 4 and 5, collected from opposite ends 

of the Burt-Izard drain, were very different from the 

other samples. Site 4 was alone in having a high 

percentage of particles larger than sand size, almost a 

third by weight. The remainder of Site 4 sediment was 

composed almost entirely of sand. Site 4 also had the 

lowest moisture content and the lowest organic 

content, as determined by loss on ignition (LOI). 

Despite its proximity to Site 4, Site 5 differed to the 

other extreme, being the lowest in sand (26%), and 

highest in silt (52%) and clay (21%). Site 5 was also 

the highest in moisture and more than double any 

other site in organic content (as indicated by LOI). 

Site 4 was located within the Burt-Izard Drain, and 

probably received high runoff flows during rain 

events, which would explain the large grain size and 

the presence of many particles of glass and what 

appeared to be road debris. Site 5 was located in a low 

velocity eddy at the mouth of the Burt-Izard, which 

explains its different texture and consistency. 

Table 4. Results of grain size analysis of sediments collected in the Missouri River and in the Burt-Izard Drain, 

near ASARCO facility, Omaha, Nebraska. Percentages of sand, silt and clay determined by the Bouyoucous 

hydrometer method, larger particles separated by sieving. 

Sample 

designation 

Percent 

larger 

than sand 

Sand 

% 

Silt 

% 

Clay 

% 

Percent 

Moisture 

Percent Loss 

on Ignition 

SED 1 0.0 47.5 42.0 10.5 28 1.4 

SED 2 0.0 63.0 29.0 8.0 27.8 1.5 

SED 4 32.0 66.0 1.0 1.0 18.2 0.80 

SED 5 0.0 26.3 52.0 21.8 41.8 3.7 

SED 24 0.0 86.5 10.5 3.0 20.6 0.8 

SED 25 1.5 81.3 12.8 4.5 22.1 1.3 

. 
10 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

The monitoring well groundwater samp le differed 

in many respects from the other water samples. 

Conductivity of the groundwater sample was nearly 

3000 μhos/cm2

, which was five-fold higher than river 

water (600 μmhos/cm2

). The conductivity of the 

groundwater sample stems largely from its very high 

chloride concentration (321 mg/L). In contrast, 

ammonia, nitrate+nitrite, sulfate, phosphate, and 

calcium concentrations were not highly elevated in the 

groundwater sample. 

Although some pore waters were low in dissolved 

oxygen immediately after collection, all samples were 

well within concentrations acceptable to C. dubia 

before the start of the toxicity test. Some pore waters 

were high in ammonia (notably Sites 4 and 5) but such 

concentrations have not been shown to be toxic to C. 

dubia (Monda 1991). Daphnids are much less 

sensitive to ammonia than fish, while having a high 

sensitivity to other toxicants, which makes them an 

ideal organism for sediment porewater testing. 

As noted in the introduction, organic material in 

the environment complexes and/or sorbs some 

contaminants, which renders them less bioavailable 

than contaminants less strongly bound to particulates 

(Tessier et al. 1979; Gobas and Zhang 1994). In all but 

Site 5, porewater DOC concentrations were in the same 

range as the surface water samples, which is very low 

for pore waters (Table 3). Site 5 porewater DOC 

concentration was quite high (15.2 mg/L), which is in 

concordance with the high LOI and fine texture of that 

sediment (Table 4). 

Metals concentrations 

The quality control results were considered to be 

acceptable based on specifications established by 

CERC. Recovery from the “blind” QA samples 

provided by EPA was very good. Quantitative 

analysis results were well within the control limits, and 

the semiquantitative results were all within 25% of the 

USEPA value, and most were within 10%. 

The results of the quantitative analysis of 

sediment are found in Table 5, and the quantitative 

analysis of aqueous samples is found in Table 6. The 

monitoring well sample (MW19) had strongly elevated 

concentrations of cadmium, zinc and arsenic, but the 

lead concentration was not high (Table 6). Site 25 had 

a somewhat elevated concentration of lead in the 

whole sediment (39.8 μg/g dry weight; Table 5), 

however whole sediment concentrations of cadmium, 

zinc, and arsenic were not remarkable. With the 

exception of MW19, none of these four elements were 

found in concentrations above the individual water 

quality in any aqueous sample. 

Table 5. Concentrations (mg/g dry weight) of total recoverable arsenic, cadmium, lead and zinc in sediment 

samples from the Omaha, NE, ASARCO study. Measurements are from quantitative analysis by ICP-MS. 

EPA 

blind QA 

Element SED 1 SED 2 SED 4 SED 5 SED 24 SED 25 sample MDLa 

Arsenic 5.60 6.50 2.90 7.80 5.90 6.90 4.60 0.31 

Cadmium < 0.27 < 0.27 < 0.27 0.43 < 0.27 < 0.27 0.78 0.27 

Lead 8.40 7.10 7.40 19.7 13.0 39.8 7.00 1.10 

Zinc 39.0 34.5 33.7 77.2 23.9 45.8 41.0 5.10 

a

 MDL = method detection limit 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 11 

Table 6. Concentrations (mg/L) of arsenic, cadmium, lead and zinc in aqueous samples 

from the Omaha, NE, ASARCO study. MW19 is the groundwater sample from 

monitoring well 19. SEDx refers to pore waters collected from the various sediment 

sites. NaCl refers to the sodium chloride reference toxicant treatments and the 

concentration of NaCl added to reconstituted river water. Hard Recon refers to the 

reconstituted water made to reflect the water quality of the river waters. 

Measurements are from quantitative analysis by ICP-MS. 

Sample identification Arsenic Cadmium Lead Zinc 

Filtration Blank 1

Filtration Blank 2

River Water 1

River Water 2

MW19

SED 1 Pore water

Dup. SED 1 Pore water

SED 2 Porewater

SED 4 Pore water

SED 5 Pore water

SED 24 Pore water

SED 25 Pore water

USEPA Blind Sample

MDLa

< 0.07 1.00 0.23 8.20 

< 0.07 0.03 0.49 2.60 

2.70 0.79 0.50 11.3 

2.70 0.52 0.64 4.20 

574 21.5 2.60 1570 

30.7 0.15 3.40 9.8 

30.4 1.20 5.20 21.9 

15.6 0.67 1.70 27.5 

23.1 0.67 8.40 34.7 

56.3 0.49 2.20 17.2 

4.00 1.10 11.5 63.7 

7.70 0.77 5.00 31.9 

13.3 18.10 4.90 12.9 

0.07 0.02 0.04 0.42 

a MDL = method detection limit 

Cadmium, zinc, arsenic, and especially lead were 

identified a priori as contaminants of concern at 

ASARCO-Omaha lead refinery. However, it is possible 

that unidentified elements (i.e., byproducts of lead 

refining processes or waste products from the orebearing material) could cause toxicity at these sites. 

Thus, we performed an additional broad-spectrum 

analysis of 64 elements in pore water, water, and 

sediment. These analyses were semiquantitative in 

nature, but have sufficient accuracy to identify 

most potential elemental contaminants of concern 

should they be present in toxic concentrations. The 

results of the semiquantitative sediment analyses are 

presented in Table 7, and the semiquantitative analysis 

of aqueous samples is in Table 8. The groundwater 

from the monitoring well was high in many elements 

(Table 8). The semiquantitatively measured 

concentrations of metals in sediments were not 

remarkable, but verified the somewhat elevated level of 

lead (40 μg/g) at Site 25 identified in the quantitative 

analysis. 
12 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Table 7. Concentrations (mg/g dry weight) of elements in sediment from the ASARCO facility in Omaha, 

Nebraska determined by semiquantitative ICP-MS scan. 

Element SED 1 SED 2 SED 4 SED 5 SED 24 SED 25 

EPA Blind 

QA 

Sample 

Ag < 0.1 < 0.1 0.2 0.2 < 0.1 0.1 0.1 

Al 4000 4000 900 7000 3000 3000 6000 

As 6.00 7.00 4.0 9 7.0 8.0 5.0 

Au 0.3 0.2 0.6 < 0.1 < 0.1 < 0.1 0.8 

B 1 2 < 1 2 < 1 < 1 3 

Ba 200 200 30 200 400 300 90 

Be < 1 < 1 < 1 < 1 < 1 < 1 < 1 

Bi < 1 < 1 < 1 < 1 < 1 < 1 < 1 

Br 10 10 10 10 10 10 10 

Ca 13000 14000 45000 16000 11000 12000 88000 

Cd 0.6 0.3 0.2 0.6 < 0.1 0.2 0.9 

Ce 20 20 10 30 20 20 30 

Co 5 6 3 7 4 5 4 

Cr 8 9 30 10 7 8 8 

Cs < 1 < 1 < 1 < 1 < 1 < 1 < 1 

Cu 9 6 30 20 3 5 8 

Dy 2 2 0.6 2 1 1 2 

Er 0.7 0.7 0.2 1 0.6 0.6 0.9 

Eu 0.5 0.5 0.2 0.6 0.4 0.4 0.6 

Fe 7000 8000 11000 10000 6000 7000 7000 

Ga 3 3 1 4 2 2 4 

Gd 2 2 0.8 3 2 2 3 

Ge < 0.1 < 0.1 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Hf < 0.1 < 0.1 < 0.1 0.1 < 0.1 < 0.1 < 0.1 

Ho 0.3 0.3 < 0.1 0.4 0.2 0.2 0.3 

I < 1 < 1 < 1 < 1 < 1 < 1 < 1 

In < 1 < 1 < 1 < 1 < 1 < 1 < 1 

Ir < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

K 800 900 200 1000 500 500 600 

La 10 10 5 10 10 10 10 

Li 5 5 < 1 7 4 4 5 

Lu < 0.1 < 0.1 < 0.1 0.1 < 0.1 < 0.1 < 0.1 

Mg 5000 5000 1000 4000 4000 4000 17000 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 13 

Table 7., continued 

EPA Blind 

QA 

Element SED 1 SED 2 SED 4 SED 5 SED 24 SED 25 Sample 

Mn 400 400 200 500 200 300 500 

Mo 0.4 0.3 9 0.6 0.3 0.3 0.8 

Na 100 200 100 200 200 200 100 

Nb < 1 < 1 < 1 < 1 < 1 < 1 < 1 

Nd 10 10 4 10 10 10 10 

Ni 10 10 30 20 10 10 10 

Os < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Pb 10 6 8 20 10 40 6 

Pd < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Pr 3 3 1 4 3 3 4 

Pt < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Rb 9 9 2 10 4 6 5 

Re < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Ru < 1 < 1 < 1 < 1 < 1 < 1 < 1 

Sb 0.2 < 0.1 0.6 0.2 0.4 0.5 0.4 

Sm 2 2 0.8 3 2 2 3 

Sn 0.1 0.2 3 < 0.1 0.1 0.2 0.2 

Sr 50 50 100 70 30 40 200 

Ta < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Tb 0.3 0.3 < 0.1 0.4 0.3 0.3 0.4 

Te < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Ti 70 80 30 60 90 70 40 

Tl 0.1 0.1 < 0.1 0.2 < 0.1 < 0.1 < 0.1 

Tm < 0.1 < 0.1 < 0.1 0.1 < 0.1 < 0.1 0.1 

U < 1 < 1 < 1 < 1 < 1 < 1 < 1 

10 20 4 20 10 10 10 

W < 0.1 < 0.1 0.5 < 0.1 < 0.1 < 0.1 < 0.1 

Y 8 8 2 10 7 7 9 

Yb 0.7 0.7 0.2 0.9 0.5 0.5 0.7 

Zn 60 50 50 90 30 50 50 

Zr 2 3 1 5 2 3 2 

V 
14 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Table 8. Concentrations of elements in water from the Omaha, NE, ASARCO study determined by 

semiquantitative ICP-MS scan. Units are mg/L unless otherwise specified. 

Element 

River 

water 

1 

River 

water 

2 

Site 

1 

Site 

1 

Dup 

Site 

2 

Site 

4 

Site 

5 

Site 

24 

Site 

25 

MW 

19 

Filter 

Blank 

1 

Filter 

Blank 

2 

EPA 

QA 

sample 

Ag <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Al 8 <0.1 10 <0.1 <0.1 18 0.5 22 54 39 2 0.84 82 

As 4.2 4.0 38.0 39.0 19.0 28.0 72.0 5.6 11 771 0.10 0.15 16.0 

B 63 57 51 46 90 95 147 52 223 6520 <1 <1 <1 

Ba 63 61 178 177 130 144 335 117 212 166 1 <1 <1 

Be 0.25 0.16 <0.1 <0.1 0.15 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 5 

Bi <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 

Br 102 103 199 196 190 121 634 138 184 551 2.8 2.3 1.5 

Caa 57 56 90 84 92 54 171 80 88 172 0.11 <0.1 <0.1 

Cd 0.92 0.61 0.27 1.3 0.7 0.75 0.55 1 1.1 26 1.2 <0.1 20 

Ce 0.17 <0.1 0.31 0.1 0.11 0.63 0.05 0.19 0.12 <0.1 <0.1 <0.1 <0.1 

Co 0.17 0.11 2.2 2.3 1.4 1.2 4.2 0.86 1.5 11 <0.1 <0.1 47 

Cr 3.1 5.2 11 16 7.6 5.6 24 9.2 17 16 0.75 0.44 7.8 

Cs <1 <1 <1 <1 <1 <1 <1 <1 <1 2.4 <1 <1 <1 

Cu 3.2 4.4 3 3.3 4.4 7.9 3 13 4.6 20 3.9 0.61 5 

Dy <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Er <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Eu <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Fe 127 71 1520 1320 40 742 4210 238 318 289 17 17 34 

Ga <0.1 <0.1 0.22 0.25 0.17 0.13 0.33 0.11 0.13 0.23 <0.1 <0.1 <0.1 

Gd <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Ge <0.1 <0.1 0.23 0.28 <0.1 0.17 <0.1 <0.1 <0.1 0.27 <0.1 <0.1 <0.1 

Hf <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Ho <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

I 1.7 1.8 15 28 28 4 56 11 11 5.8 <1 <1 <1 

In <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 

Ir <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Ka 5.4 5.7 5.1 5.6 6.3 6.5 8.4 5.1 7 92 <0.1 <0.1 <0.1 

La 0.11 <0.1 0.18 <0.1 <0.1 0.36 <0.1 0.11 <0.1 <0.1 <0.1 <0.1 <0.1 

Li 45 46 35 34 48 29 17 40 40 92 <1 <1 <1 

Lu <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Mga 23 22 38 36 37 15 67 32 36 34 <0.1 <0.1 <0.1 

a

Concentration units mg/mL 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 15 

Table 8., continued 

Element 

River 

water 

1 

River 

water 

2 

Site 

1 

Site 

1 

Dup 

Site 

2 

Site 

4 

Site 

5 

Site 

24 

Site 

25 

MW 

19 

Filter 

Blank 

1 

Filter 

Blank 

2 

EPA 

QA 

sample 

Mn 17 5 4970 4630 2800 608 6820 1040 2160 2660 4.9 1.1 52 

Mo 3.2 3.3 5.1 5.4 4.8 14 6.8 7.8 10 56 0.2 <0.1 <0.1 

Naa 67 72 69 68 77 60 94 65 87 532 <0.1 <0.1 <0.1 

Nb <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 

Nd <0.1 <0.1 0.14 <0.1 <0.1 0.29 <0.1 0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Ni 3.7 2.2 7.2 19 6.2 4.7 10 8.9 19 14 2.7 0.36 34 

Os <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Pb <1 <1 3.7 5.6 1.8 9.2 2.8 12 5.8 3 <1 <1 5.4 

Pd <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Pr <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Pt <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Rb 2.3 2.3 3.1 3 4.4 3 3 2.7 3.3 134 <0.1 <0.1 <0.1 

Re <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.78 <0.1 <0.1 <0.1 

Ru <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 

Sb 0.64 1 0.84 0.78 2.4 8.2 1 4 12 430 0.1 <0.1 <0.1 

Sm <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Sn <0.1 0.47 0.38 0.51 0.54 0.93 0.53 0.58 0.4 1.4 <0.1 <0.1 <0.1 

Sr 472 522 734 739 798 412 1172 639 752 1230 <1 <1 <1 

Ta <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Tb <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Te <0.1 <0.1 0.16 <0.1 <0.1 <0.1 0.14 <0.1 <0.1 0.24 <0.1 <0.1 <0.1 

Ti 1.4 0.62 2.3 1.7 1.2 1.7 2.9 1.8 4.9 8.3 <0.1 0.14 <0.1 

Tl <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.69 <0.1 <0.1 <0.1 

Tm <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

U 4.2 4.4 2.8 2.8 6.2 4.1 <1 5.5 7.4 5.6 <1 <1 <1 

V 2.4 2.3 1.6 1.4 1.6 1.8 0.68 2.8 3.2 2.2 <0.1 <0.1 25 

W 0.14 0.13 0.16 0.17 0.26 0.44 0.13 0.11 0.32 13 <0.1 <0.1 <0.1 

Y <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 

Yb <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 

Zn 21 <1 6.3 22 26 37 21 67 44 2050 12 4 22 

Zr <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 

a

 Concentration units mg/mL 
16 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

The USEPA chronic criteria for selected metals in the measured hardness values. None of the sediment 

water are found in Table 9. Many of the criteria are pore waters exceeded the USEPA water quality criteria 

dependent on water hardness. Table 10 contains the of the quantitatively measured metals. 

criteria for the sediment pore waters, calculated using 

Table 9. USEPA Water Quality Criteria for selected trace metals or 

the hardness-based algorithms used to determine the criteria [taken 

from Wildhaber and Schmitt (1996) and USEPA (1999)]. 

Element USEPA Chronic criteria (mg/L) 

Arsenic 190 

Cadmium e (0.7852[ln(hardness)]-3.490 

Copper e (0.8545[ln(hardness)]-1.702 

Lead e (1.2730[ln(hardness)]-4.705 

Nickel e (0.8460[ln(hardness)]-1.1645 

Zinc e (0.8473[ln(hardness)]+0.7614 

Table 10. Calculated USEPA Water Quality Criteria Values for pore waters, river waters, and 

groundwater based on averaged measured hardness for selected metals. MW19 is groundwater 

from monitoring well 19, located on the ASARCO Omaha property. SEDx refers to pore waters 

collected from the various sites. All values in mg/L. 

Site 

Hardness 

(mg/L CaCO3) Cu Cd Pb Ni Zn 

MW19

River water 1

River water 2

SED1

SED2

SED4

SED5

SED24

SED25

550 39.9 4.3 27.9 666.9 449.3 

262 21.2 2.4 10.8 356.1 239.7 

280 22.4 2.5 11.8 376.7 253.6 

384 29.4 3.3 17.6 492 331 

333 26.0 2.9 14.7 436 294 

242 19.8 2.3 9.8 333 224 

540 39.3 4.3 27.2 657 442 

324 25.4 2.9 14.2 426 287 

369 28.4 3.2 16.8 476 320 

The high concentration of lead in Site 25 sediment 

was not strongly reflected in the pore water, likely 

because of acid-volatile sulfide (AVS) concentrations 

in Site 25 sediment. Lead and certain other metals, 

measured as simultaneously extractable metals (SEM), 

are not biologically available when bound to AVS (Di 

Toro et al. 1992). One mole of AVS has the capacity to 

bind one mole of SEM. For a given total or SEM metal 

concentration, as the ratio of SEM to AVS becomes 

greater than one, a sharp increase in porewater metals 

is expected to follow, providing there is a moderate or 

high concentration of metal in the sediment (a 

SEM/AVS ratio greater than one can be 

inconsequential if both the AVS and SEM 

concentrations are very low). Concentrations of SEM 

may be found in Table 11, and a comparison of AVS 

and SEM concentrations can be found in Table 12. If 

the summation of the molar concentration of SEM 

minus the AVS concentration (bottom row, Table 11) is 

greater than one, then metals exceed the capacity for 

AVS sequestration and are assumed to be 

bioavailable. 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 17 

Table 11. Concentrations of simultaneously extracted metals (mg/g) in sediments collected in the vicinity 

of the ASARCO lead refining facility in Omaha, Nebraska. 

Element Site 1 Site 2 Site 4 Site 5 Site 24 Site 25 MDLa 

Arsenic 1.70 2.20 0.48 1.80 1.80 2.30 0.020 

Cadmium 0.18 0.20 0.17 0.35 0.099 0.19 0.010 

Copper 3.00 2.90 3.50 5.90 1.10 3.30 0.010 

Lead 6.60 3.80 26.10 38.30 9.20 43.2 0.030 

Nickel 3.60 3.60 3.00 6.50 1.90 3.10 0.020 

Zinc 9.70 6.90 79.80 40.80 5.80 23.80 0.490 

a MDL= Method detection limit 

Table 12. Molar concentrations (μmol/g) of acid-volatile sulfide (AVS) and simultaneously extracted metals 

(SEM) in sediments collected in the vicinity of the ASARCO lead refining facility in Omaha, Nebraska. 

Element Site 1 Site 2 Site 4 Site 5 Site 24 Site 25 

AVS 1.60 0.095 8.40 5.00 0.015 1.30 

Arsenic 0.023 0.029 0.006 0.024 0.024 0.031 

Cadmium 0.002 0.002 0.002 0.003 0.001 0.002 

Copper 0.047 0.046 0.055 0.093 0.017 0.052 

Lead 0.032 0.018 0.126 0.185 0.044 0.209 

Nickel 0.061 0.061 0.051 0.111 0.032 0.053 

Zinc 0.148 0.106 1.221 0.624 0.089 0.364 

SSEM 0.313 0.262 1.461 1.04 0.207 0.711 

SSEM- AVS -1.287 0.167 -6.939 -3.96 0.192 -0.589 
18 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

At equilibrium, different metals are selectively 

bound by AVS, depending on the solubility of the 

metal sulfide (Wildhaber and Schmitt 1996). Among 

the metals and metalloids of concern, mercury is the 

most strongly bound, followed in order by silver, 

copper, cadmium, lead, zinc, nickel, arsenic, iron, 

manganese, and chromium. Therefore, for example, a 

high concentration of copper could bind all available 

AVS, leaving none to bind cadmium, lead or other 

metals less strongly bound by AVS. Wildhaber and 

Schmitt (1996) used AVS to estimate the porewater 

concentrations of metals, under the assumption that 

AVS limits the solubility of these elements. In our 

study, we did not measure simultaneously extractable 

mercury or silver. However, the molar concentration of 

these elements is likely to be low based on extant 

information, and mercuric and silver sulfides are 

usually not dissolved by SEM extraction. We 

therefore ignored these elements in our estimation of 

SEM binding by AVS. 

USEPA water quality criteria (and risk assessment 

in general) evaluate contaminants individually--not in 

combination, as they often occur in the environment. 

To evaluate complex mixtures in sediments, Wildhaber 

and Schmitt (1996) expanded upon the concept of 

"toxic units" first proposed by Sprague and Ramsay 

(1965). A toxic unit is one multiple of the metal’s 

USEPA water chronic criteria concentration in pore 

water. Because the toxicity of metals is often additive, 

the summation of the toxic units (STU) for each metal 

accounts for the cumulative toxicity of the mixture after 

all its components are scaled for toxicity. Therefore, if 

the summed toxic units for all metals in a pore water 

(measured or estimated) is one or greater, the sediment 

is assumed to be potentially toxic. The estimated toxic 

units of the sediment pore waters, calculated using the 

method of Wildhaber and Schmitt (1996), are presented 

in Table 13. In our study porewater element 

concentrations were measured directly and thus we 

were also able to calculate toxic units directly (Table 

14). The two sets of results agree in that Site 24, the 

only sediment to have an estimated total toxic unit 

value greater than one, also had the highest measured 

porewater toxic units. However, in five of the six 

sediments, the model predicted that sulfides would 

sequester all or nearly all of the metals, and the model 

underestimated the measured porewater STU. The 

most serious error was at Site 4 (Table 14), where the 

model predicted that all metals would be sequestered, 

and the measured concentration was twice that which 

would be predicted to cause toxicity (although no 

toxicity was actually observed at this site). There was 

little AVS in Site 24 sediment. At that site the model 

predicted a somewhat higher STU than the value from 

measured concentrations. This site was also not toxic. 

This may be due to deficiencies in the AVS and toxic 

units models, or it may also reflect the methodology of 

pore water collection. When pore water is collected in 

the field, a very small amount of fines can pass 

through the filter. These fines can include solid-phase 

metals bound to sulfides. The fines are removed by 

filtration prior to acidification of the analytical sample 

and by centrifugation prior to toxicity testing. 

However, prior to removal of fines, dissolved oxygen 

concentrations may increase in the pore waters. This 

would oxidize sulfides and release metals to the pore 

water. Thus, we would see small increases in 

porewater metals concentrations. The porewater 

extraction method we employed is a preferred method 

for minimizing the amount of fines in collected pore 

water (Carr and Chapman 1995). However, some fines 

do pass through the 8-μm filter, and some sediment 

types will pass more fines than others. The only 

porewater samples that contained any sediment visible 

to the naked eye prior to centrifugation were Sites 4 

and 5. The presence of these fines, although they 

were removed prior to analysis, may be partially 

responsible for the unexpectedly high concentration of 

metals in Site 4 pore water. 

Table 13. Calculated Toxic Units derived from 

estimated porewater concentrations of copper, 

cadmium, lead, zinc, nickel, and arsenic based on 

Wildhaber and Schmitt (1996). 

Toxic Units 

Site Cu Cd Pb Zn Ni As Total 

Site 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Site 2 0.00 0.00 0.00 0.00 0.02 0.04 0.07 

Site 4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Site 5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Site 24 0.02 0.19 3.11 0.01 0.02 0.05 3.40 

Site 25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 19 

Table 14. Toxic Units (measured porewater 

concentration / USEPA water quality criteria) for 

copper, cadmium, lead, zinc, nickel, and arsenic. Nickel 

and copper concentrations were obtained from 

semiquantitative scan (Table 8). Cadmium, lead, zinc 

and arsenic concentrations were obtained from 

quantitative measurements (Table 6). 

Toxic Units 

Site Cu Cd Pb Zn Ni As Total 

Site 1 0.10 0.20 0.24 0.05 0.03 0.16 0.78 

Site 2 0.17 0.23 0.12 0.09 0.01 0.08 0.70 

Site 4 0.40 0.29 0.86 0.15 0.01 0.12 1.83 

Site 5 0.08 0.11 0.08 0.04 0.02 0.30 0.63 

Site 24 0.51 0.38 0.81 0.22 0.02 0.02 1.96 

Site 25 0.16 0.24 0.30 0.10 0.04 0.04 0.88 

Toxicity testing 

C. dubia normally reproduces 

parthenogenetically, producing only fertile female 

offspring. Reproduction of a large number of male 

offspring is an indication of stress that can be caused 

by numerous environmental factors including 

changing light, temperature, or food (Barnes 1980). 

Identification of the sex of neonate ceriodaphnids is 

impossible without undue stress to the organism, so 

males are sometimes inadvertently included as test 

organisms. Presence of a large number of males in a 

test is an indication of a stressed population of test 

organisms and could invalidate the test. In this study, 

of 220 ceriodaphnids used in the test, only nine were 

identified as male. Seven of the nine were identified as 

having the same parent (all the offspring of that 

individual were male). Replicates stocked with male 

ceriodaphnids were excluded from all analyses. 

Survival of ceriodaphnids was ‡90% and 

reproduction was high in the CERC well water, the 

Hard Recon, in the river waters, and in the upstream 

sediment (Tables 15 and 16). In the reconstituted river 

water, survival was somewhat reduced (75%) and 

reproduction was low compared to other references 

(8.75 young per female vs 31 - 39). This may stem 

partly from the fact that two male organisms were 

stocked into this treatment. Although these replicates 

were excluded from the analysis, the reduced sample 

size compromises statistical interpretation. All animals 

were cultured in this reconstituted river water and the 

cultures were highly successful. If there was any 

problem with the reconstituted river water, it occurred 

after the test was begun. Survival was 100% in the 

Hard Recon, which was made similarly to the 

reconstituted river water, but with a higher 

concentration of salts added, and 100% in the CERC 

well water procedural control, which was the source 

water of both the reconstituted river water and the 

Hard Recon. The chemistry of the reconstituted river 

water was intermediate between that of these two 

treatments, and the observed reduction in survival and 

reproduction in this treatment is therefore inexplicable. 

Table 15. Percent survival of non-male Ceriodaphnia 

dubia exposed to sample and control water in a 7-day 

toxicity test on samples collected in the vicinity of the 

ASARCO lead refining facility, Omaha, Nebraska. 

Ceriodaphnia identified as male were excluded. 

MW19 is the groundwater sample from monitoring well 

19. SEDx refers to pore waters collected from the 

various sediment sites. NaCl refers to the sodium 

chloride reference toxicant treatments and the 

concentration of NaCl added to reconstituted river 

water. Hard Recon refers to the reconstituted water 

made to reflect the water quality of the collected river 

waters. 

Dilution 

Treatment 6.25 12.5 25 50 100 

MW19 78 30 0 0 0 

River 100 water 1 

River 100 water 2 

SED1 100 

SED2 90 

SED24 100 

SED25 100 

SED4 90 89 100 100 

SED5 90 

Reconstituted 75 river water 

Hard Recon 100 

NaCl 100 40 0 

Well 100 
20 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Table 16. Mean reproductive output of Ceriodaphnia dubia exposed to sample waters and reference 

waters in a 7-day toxicity test. Reproductive output is the total number of young produced during the 

test, regardless of the individual's survival. Number of replicates is in parenthesis. Standard error of the 

mean is in brackets. Ceriodaphnia identified as male were excluded. Treatments significantly lower in 

reproduction than Site 1 and Site 2 are indicated with two asterisks (**). Treatments significantly lower 

than Site 1, but not Site 2, are indicated with a single asterisk (*). MW19 is the groundwater sample from 

monitoring well 19. SEDx refers to pore waters collected from the various sediment sites. NaCl refers to 

the sodium chloride reference toxicant treatments and the concentration of NaCl added to reconstituted 

river water. Hard Recon refers to the reconstituted water made to reflect the water quality of the river 

waters. 

Dilution 

Treatment 6.25% 12.5% 25% 50% 100% 

33.8 SED1 (10) [4.55] 

26.1 SED2 (10) [2.28] 

20.56 7.6** 0** 0** 0** MW19 (9) [5.27] (10) [5.17] (10) [0] (10) [0] (10) [0] 

48.44 River water 1 (9) [4.5] 

32.6 River water 2 (10) [2.9] 

32.4 SED24 (10) [2.55] 

15.88* SED25 (8) [3.35] 

26.3 32.56 28.12 31.56 SED4 (10) [5.51] (9) [5.39] (8) [5.66] (9) [4.83] 

23.5 SED5 (10) [3.36] 

Reconstituted 8.75** 

river water (8) [3.95] 

38.7 Hard recon (10) [4.44] 

1.11** 0** 0** NaCl (9) [0.73] (10) [0] (10) [0] 

31.2 

Well (10) [2.13] 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 21 

In the positive controls (2.5, 1.25, and 6.125 parts 

per thousand sodium chloride), survival was strongly 

reduced in the two higher concentrations, and 

reproduction was reduced in all three concentrations. 

This is within, but near the higher end, of the range of 

sodium chloride sensitivity seen in other 

Ceriodaphnia tests at our facility. 

Survival and reproduction were significantly 

(p<0.05) reduced in all but the lowest dilution (6.25%) 

of the groundwater sample, compared to the upstream 

porewater references Sites 1 and 2. Reproduction was 

not reduced significantly in the lowest concentration 

of the groundwater sample. 

Survival was 100% and reproduction was very 

high in both river water samples. Survival was ‡90% in 

all sediment pore waters. Reproduction in pore waters 

from the two sites associated with the Burt-Izard drain 

was not significantly reduced (Table 16). Because of a 

priori concerns that Site 4 would be highly toxic, a 

dilution series was performed on pore water from this 

site. However, all concentrations, including the 100% 

porewater concentration, were not toxic. Site 24, which 

had the highest porewater metal concentrations of any 

sample, was not significantly different in reproduction 

from the reference pore waters. Pore water from Site 25 

was significantly reduced in reproduction compared to 

Site 1, but not significantly reduced compared to Site 

2. Metals concentrations in Site 25 pore water were 

somewhat elevated compared to the references, but in 

no case did the concentrations of measured metals 

exceed the water quality criteria. The summation of 

measured porewater metal toxic units at this site was 

0.88 (where a value of greater than 1 theoretically 

would be potentially toxic). Therefore, this site, which 

may have been marginally toxic, contained marginally 

high metals concentrations. 

We expected groundwater influences on the 

sediment to be stronger in the Burt-Izard Drain than in 

the river sites. We did not find this to be so. A 

strong rain event, such as the one occurring the night 

prior to the sampling trip, could flush pore water from 

the large-grained sediments we found within the BurtIzard drain. The result would be a short-term decrease 

in toxicity until the pore water regained equilibrium 

with the sediment particles, or until more groundwater 

intruded into the sediment at that site. However, this 

does not appear to have been the case at Site 4, the 

sampling location lying within the Burt-Izard drain. 

Porewater ammonia was somewhat elevated at Site 4 

(Table 2), which would not be expected in the case of 

dilution with rainwater. Also, whole sediment 

concentrations of most elements were lower at Site 4 

(Table 7) than at most other sites. Therefore, sampling 

directly after a strong rain event does not seem to 

have been responsible for the lack of toxicity at this 

site, which would have been the site most likely to be 

affected by the rain event. 

The daily measurements of dissolved oxygen and 

pH and conductivity associated with the toxicity tests 

were not remarkable and were not highly variable 

within treatments. All dissolved oxygen 

concentrations were at or above 7 mg/L. 

Principal components analysis 

There are 741 pairs of elements from the sediment 

data and 465 pairs in the water data, which are too 

many to list. As should be expected, some elements 

were strongly correlated with each other, especially in 

sediment samples. Therefore we made use of principal 

component analysis to develop a series of indices that 

summarize the element concentration data; i.e., the 

principal components are an attempt to develop an 

index of a sample’s elemental composition. 

Descriptions of the first three principal 

components for sediment numbers are listed in Table 

17. The first three components account for 73%, 17% 

and 6% of the sediment data variability, respectively. 

The first three principal components for water data are 

described in Table 18. Those components account for 

47%, 23% and 11% of the water data variability, 

respectively. The first sediment principal component 

is highly correlated with over half of the elements. 

This is possible since many of those elements were 

highly correlated to each other. In both cases the first 

principal component accounts for much of the 

variation in the data sets. The third principal 

component has few strong correlations with the 

element concentrations. In both datasets the principal 

components 4 and beyond are not meaningful. No 

strong patterns were obvious except that the first 

sediment principal component reflects the relatively 

low concentrations of many elements at Site 4 (Fig.2). 
22 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Table 17. Correlation of concentrations of elements found in sediment samples with the first three principal 

components calculated from those numbers. Correlations with absolute values greater than 0.8 are in bold. 

Sediments were collected in the vicinity of the ASARCO lead refining facility, Omaha, Nebraska. 

Element PC1 PC2 PC3 Element PC1 PC2 PC3 

Y 1 -0.01 0 Co 0.9 0.39 -0.08 

Li 1 0.03 0 Ba 0.85 -0.51 -0.1 

Pr 0.99 -0.03 -0.12 Zr 0.85 0.31 -0.38 

Tb 0.99 -0.02 -0.13 Ti 0.83 -0.52 0.16 

Al 0.98 0.19 -0.03 Dy 0.82 0.42 0.39 

Er 0.97 0.21 -0.08 Mn 0.74 0.62 0.1 

Sm 0.96 0.10 -0.2 Na 0.62 -0.29 -0.47 

Gd 0.96 0.10 -0.2 Cd 0.44 0.79 0.21 

Nd 0.96 -0.25 0.02 Pb 0.29 -0.07 -0.82 

La 0.96 -0.25 0.02 Zn 0.29 0.91 -0.18 

Eu 0.96 0.26 0.07 Fe -0.46 0.84 -0.19 

Ce 0.96 0.12 -0.21 Cu -0.5 0.85 -0.11 

K 0.96 0.22 0.19 Sr -0.56 0.83 -0.03 

Mg 0.95 -0.21 0.18 Ni -0.66 0.63 -0.29 

Yb 0.94 0.32 0.08 Sb -0.73 -0.32 -0.53 

Ho 0.93 0.34 0.08 Ca -0.87 0.48 -0.03 

Ga 0.92 0.37 0.11 Cr -0.89 0.44 -0.05 

Rb 0.91 0.32 0.17 Mo -0.94 0.33 -0.05 

V 0.91 0.21 0.02 Sn -0.97 0.21 -0.01 

As 0.9 -0.04 -0.42 

Table 18. Correlation of concentrations of elements found in water samples with the first three principal 

components calculated from those numbers. Correlations with absolute values greater than 0.8 are in bold. 

Element PC1 PC2 PC3 Element PC1 PC2 PC3 

Co 0.98 0.06 -0.12 B 0.58 0.31 0.27 

Ba 0.97 0.23 -0.02 Rb 0.51 0.24 0.1 

Br 0.96 -0.25 0.01 Mo 0.4 0.85 -0.27 

Ga 0.95 -0.15 -0.18 Zn 0.36 0.71 0.17 

Ca 0.93 -0.24 0.2 Pb 0.34 0.83 -0.16 

Cr 0.92 0.07 0.22 Sn 0.3 0.45 -0.63 

I 0.91 -0.08 0.09 Sb 0.08 0.91 0.09 

Sr 0.87 -0.3 0.33 W 0.06 0.7 -0.29 

Mn 0.86 0.33 0.03 Al -0.09 0.86 0.25 

As 0.86 -0.01 -0.42 Ce -0.18 0.68 -0.65 

Mg 0.82 -0.35 0.4 Cd -0.26 0.68 0.61 

K 0.76 -0.03 -0.09 Cu -0.27 0.67 -0.16 

Fe 0.73 0.08 -0.34 U -0.62 0.52 0.41 

Ni 0.71 0.42 0.45 V -0.67 0.49 0.51 

Na 0.7 -0.32 0.47 Li -0.78 0.07 0.44 

Ti 0.67 0.49 0.42 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 23 

There was no strong relationship between 

Ceriodaphnia reproduction and element composition. 

This is not surprising because, in general, 

reproductive rates did not differ between sites 

significantly. In particular none of the principal 

components adequately explain the low reproductive 

rates observed at Site 25. Inspection of 

concentrations of individual element concentrations 

similarly does not satisfactorily explain the low 

reproduction at Site 25. 

Cluster analysis 

Hierarchical cluster analysis was used to evaluate 

similarities between sites, to see if sites differed in 

water quality depending on their location in the study. 

MW19 was excluded from the analysis because its 

high concentrations of many elements caused undue 

influence on the analysis. 

Sediment samples 

SED5 

SED4 

SED25 

SED24 

SED2 

SED1 

-10 -5 0 5 

First Principal Component 

Figure 2. Comparison of the first principal component 

calculated from element concentration data of 

sediment samples between study sites in the vicinity 

of the ASARCO lead refining facility, Omaha, 

Nebraska. 

Figure 3 shows the results for analysis of 

sediment data and demonstrates that Sites 1 and 2 are 

very similar in elemental composition, as are Sites 24 

and 25. Sites 4 and 5 do not group as closely. This is 

not surprising, despite their physical proximity, 

because of the physical differences between these two 

sites (Table 4). Site 4 also stood out in the principal 

component analysis since its concentrations of most 

elements were noticeably lower than those of the other 

sites. 

Figure 4 shows the results for analysis of the 

water data. Again, the data reflects the layout of the 

study sites. RW1 and RW2 are quite close together, 

as are the pairs (Sites 1 and 2) and (Sites 24 and 25). 

Again, Sites 4 and 5 do not group closely to each 

other. 

Sediment samples 

12 

10 

8 

6 

4 

SED4 

SED5 

2 

Figure 3. Results of hierarchical cluster analysis of 

element concentrations measured from sediment 

samples collected near the ASARCO facility in Omaha, 

Nebraska 

SED1SED2SED24SED25
samples

24 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Water samples composition can also be inspected by the use of 

principal component plots (biplots). These plots 

simply plot each site in a two -dimensional graph using 

their first two principal component scores. Figure 5 

10 shows the biplot from sediment samples. The same 

groupings observed in the cluster analysis are found 

here. Sites 1 and 2 fall very close to each other. Sites 

24 and 25 are also fairly close, especially in respect to 

8 the first principal component. Sites 4 and 5 are 

Similarity between sites in terms of elemental

Second Principal Component 

separated. Figure 6 shows this pattern one more time 

in the water data, with the addition of RW1 and RW2 

6

MW-19 

SED1 

SED24 SED25 

SED4 

SED5 

being fairly close to each other. In summary, the 

cluster analysis shows us that samples that were 

similar in location and in type were also similar in water 

4 under the hydrologic conditions that they were 

sampled. This is not surprising, but does serve as 

verification that sampling was correctly conducted and 

2 River River 

Water 1 Water 2 

that sediments and sediment porewater chemistry 

varied according to location. 

SED2

quality and in elemental composition at the time and 

Figure 4. Results of hierarchical cluster analysis of 

element concentrations measured from aqueous 

samples collected near the ASARCO facility, Omaha, 

Nebraska. 

Sediment samples Water samples 

6 

4 

4 

2 

2 

0

SED1 

SED2 

SED24 

SED25 

SED4 

SED5 

0 

-2 -2 

-4 -4 

River water 1 

River water 2 

SED1 SED2 

SED24 

SED25

SED4 

SED5 

-15 -10 -5 0 5 10 -5 0 5 

First Principal Component First Principal Component 

Figure 5. Biplot of element concentration data Figure 6. Biplot of element concentration data 

measured from sediment samples. measured from water samples. Second Principal Component 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 25 

Conclusions 

Water quality variables of surface and sediment 

pore water, including dissolved oxygen, hardness, 

alkalinity, temperature, pH, ammonia, sulfate, 

nitrate+nitrite, chlorides, and calcium, were clearly 

within acceptable limits for Ceriodaphnia dubia 

growth and reproduction. 

The groundwater from the monitoring well 

(MW19) was highly toxic, and high in many toxic 

elements. It had to be diluted to a concentration of 

6.25% with reconstituted river water before survival 

and reproduction were not significantly different from 

the references. Although this study was not intended 

to encompass the dilution rate of groundwater with 

river and sediment pore waters in situ, one would 

surmise that groundwater would be quickly and highly 

diluted (i.e., to <6.25%) as it enters the Missouri River. 

Metals of toxicological concern were not highly 

elevated in sediments, sediment pore waters, or river 

waters. At the one site where lead was somewhat 

elevated in the sediment (Site 25), it was present in the 

pore water at a concentration of less than one-third of 

the USEPA chronic criteria for surface waters. 

Ceriodaphnia reproduction may have been somewhat 

impaired at this site. Using the toxic units approach, 

based on measured porewater concentrations, metals 

concentrations in pore water at this site approached 

but did not exceed the concentration where chronic 

toxicity might be expected. Perhaps these marginally 

high concentrations of metals impacted Ceriodaphnia 

reproduction, or other unmeasured contaminants, such 

as organic chemicals, may have been involved. The 

reduction in reproduction was not clearly significant. 

Sediments in large rivers such as the Missouri are 

in a constant state of flux; they are deposited, resuspended, and transported continuously. Transport 

of sediment in rivers is well-studied (Meade et al. 

1990). Sediments that were present in the early spring 

were completely removed by higher flows before the 

fall sampling trip. Much of the substrate on the 

ASARCO waterfront was solid slag at the time of the 

sampling trip. Weathering of slag and movement of 

groundwater should provide a constant source of lead 

and other contaminants from this site. However, the 

dilution factor of the Missouri River is immense, and 

apparently sediment does not linger long at the site 

before passing on downstream. A prolonged period of 

low flow could cause sediments to remain in place long 

enough for contaminants from the ASARCO site to 

reach toxic concentrations along the waterfront. 

However, the United States Army Corps of Engineers 

maintains regular, annual periods of high flow for 

barge traffic on the river. Sediment accumulating 

during the winter low flow period apparently washes 

away during the following navigation season. 

Our intent was to perform this study after a 

prolonged low-flow period. Under such conditions, 

the net flow of groundwater from the ASARCO Omaha 

facility is most likely to be toward the Missouri River, 

and pore waters collected under such conditions 

would contain higher concentrations of groundwater 

originating from the ASARCO facility. During or 

following high water periods, the pore waters are more 

likely to be dominated by river water. Even after 

equilibration with the sediments, such pore waters 

would be expected to have much lower elemental 

concentrations than groundwater from the site. 

Unfortunately, the need for the data and information 

presented in this report necessitated that we conduct 

the study in the early fall of 1998, following a summerlong high water period resulting from record snowfall 

during the winter of 1997-1998. Therefore, 

groundwater adjacent to the river may have been 

dominated by river water at the time of sampling. 

This contention is supported to a degree by 

earlier monitoring data for MW19, the one we sampled 

and tested. This well is the one closest to the 

Missouri River and therefore the one likely to be most 

influenced by river water. Monitoring samples taken 

between August of 1995 and January of 1998 had 

concentrations of calcium, chlorides and sulfates 

averaging 2 to 5.3 times higher than they were during 

our study (Table 19). It could be that groundwater 

had in fact been diluted by river water prior to our 

arrival. However, the chloride concentration of MW19 

water was over five times that of the river water during 

this study, and the concentration of arsenic found in 

the water taken from MW19 (574 mg/L), was very close 

to the historical average arsenic concentration (598 

mg/L, Table 19). 
26 BIOLOGICAL SCIENCE REPORT USGS/BRD/BSR—2001-0004 

Table 19. Historical water quality of monitoring well 

19 (MW19) and water quality of MW19 when sampled 

in this study (October 5, 1998). Historical water quality 

from unpublished data provided to USEPA by the 

Nebraska Department of Environmental Quality. All 

values in mg/L. 

Date Calcium Chloride Sulfate Arsenic 

Aug. 1995 431 1396 789 0.260 

Mar. 1996 507 1484 1235 0.770 

May 1996 442 1709 1167 0.390 

Jan. 1997 414 1588 979 0.660 

May 1997 272 1136 864 0.680 

Jan. 1998 195 1003 900 0.830 

Historical 377 1386 989 0.598 

average 

Oct. 1998 

(this study) 185 321 186 0.574 

In this study, we found measurable 

concentrations of metals in pore waters that, according 

to the Toxic Units model of Wildhaber and Schmitt 

(1996), should have had virtually all metals bound to 

sulfides and therefore not present in the pore water. 

This disagreement may have been due to deficiencies 

in the model or due to release of metals by oxidation of 

sulfides attached to sediment particles that were not 

immediately removed by the porewater extraction 

technique. The Wildhaber and Schmitt model (using 

measured porewater concentrations) predicted that 

two sites would be toxic, but no toxicity was observed 

at those sites. 

Acknowledgements 

This study was funded by the U.S. Environmental 

Protection Agency, IAG DW14952122-01-1. We thank 

John Delashmit, Denny Buckler, and William 

Brumbaugh for their reviews of the manuscript. 

Thanks to Steve Olson, Barry Poulton, and Mark 

Laustrup for their help in the field, and to Steve Olson, 

Patty Kohn and Julie Blubaugh for their help in the 

laboratory. Lynne Johnson provided editorial, layout 

and publication support. We also appreciate the 

services of the U.S. Fish and Wildlife Service field 

office in Grand Island, NE. 

Literature Cited 

Agresti, A. 1990. Categorical data analysis . John Wiley 

and Sons, New York, NY. 558 pp. 

Barnes, R.D. 1980. Invertebrate Zoology. Saunders 

College, Philadelphia, PA. 1089 pp. 

Brumbaugh, W.G. and J.W. Arms. 1996. Quality 

control considerations for the determination of 

acid-volatile sulfide and simultaneously extracted 

metals in sediments. Environmental Toxicology 

and Chemistry 15:282-285. 

Brumbaugh, W.G., C.G. Ingersoll, N.E. Kemble, T.W. 

May and J.L. Zajicek. 1994. Chemical 

characterization of sediments and pore water from 

the upper Clark Fork River and Milltown 

Reservoir, Montana. Environmental Toxicology 

and Chemistry 13:1971-1983. 

Carr, R.S. and D.C. Chapman. 1995. Comparison of 

methods for conducting marine and estuarine 

sediment porewater toxicity tests - extraction, 

storage and handling techniques. Archives of 

Environmental Contamination and Toxicology 

18:69-77. 

DiToro, D.M., J.D. Mahony, D.J. Hansen, K.J. Scott, 

A.R. Carlson, and G.T. Ankley. 1992. Acid-volatile 

sulfide predicts the acute toxicity of cadmium and 

nickel in sediments. Environmental Science and 

Technology 26:96-101. 

Gobas, F.A.P.C. and X. Zhang. 1994. Interactions of 

organic chemicals with particulate and dissolved 

organic matter in the aquatic environment. Pages 

83-92 in J.L. Hamelink, P.F. Landrum, H.L. 

Bergman, and W.H. Benson, editors. 

Bioavailability: Physical, Chemical, and Biological 

Interactions. Lewis Publishers, Boca Raton, FL. 

239 pp. 

Hochberg, Y. and A.C. Tamhane. 1987. Multiple 

comparison procedures. John Wiley and Sons, 

New York, NY. 450 pp. 

Johnson, R.A. and D.W. Wichern. 1992. Applied 

multivariate statistical analysis. 3rd edition. 

Prentice Hall, Englewood Cliffs, NJ. 642 pp. 
TOXICITY AND BIOAVAILABILITY OF METALS IN THE MISSOURI RIVER 27 

Kaufman L. and P.J. Rousseeuw. 1990. Finding groups 

in data: an introduction to cluster analysis. J. 

Wiley, New York, NY. 342 pp. 

May, T.W., R.H. Wiedemeyer, W.G. Brumbaugh, and 

C.J. Schmitt. 1997. The determination of metals in 

sediment pore waters and in 1N HCl-extracted 

sediments by ICP-MS. Atomic Spectroscopy 

18:133-139. 

Meade, R.H., T.R. Yuzyk, and T.J. Day. 1990. 

Movement and storage of sediment in rivers of 

the United States and Canada. Pages 255-280 in 

M.G. Wolman and H.C. Riggs, editors. Surface 

Water Hydrology. Geological Society of America, 

Boulder, CO. 

Monda, D.P. 1991. Toxicity of ammonia in sewage 

effluent to aquatic macroinvertebrates. Masters 

thesis. University of Missouri, Columbia, MO. 98 

pp. 

Onuf, C.P., D.C. Chapman, and W.M. Rizzo. 1996. 

Inexpensive, easy to construct coring devices 

usable from small boats. Journal of Sedimentary 

Research 66:1031-1032. 

Snedecor, G.W. and W.G. Cochran. 1989. Statistical 

methods. 8th edition. Iowa State University Press, 

Ames, IA. 503 pp. 

Sprague, J.B. and B.A. Ramsay. 1965. Lethal levels of 

mixed copper-zinc solutions for juvenile salmon. 

Journal of the Fisheries Research Board of Canada 

22:425-432. 

Tessier, A., P.G.C. Campbell, and M. Bisson. 1979. 

Sequential extraction procedure for the speciation 

of particulate trace metals. Analytical Chemistry 

51:844-851. 

U.S. Environmental Protection Agency (USEPA). 

1994. Short-term methods for estimating the 

chronic toxicity of effluents and receiving waters 

to freshwater organisms. EPA-600-4-91-002. 

Cincinnati, OH. 246 pp. 

U.S. Environmental Protection Agency (USEPA). 1999. 

National recommended water quality criteria: 

correction. EPA 822-Z-99-001. USEPA, 

Washington, D.C. 25 pp. 

Wildhaber, M.L. and C.J. Schmitt. 1996. Estimating 

aquatic toxicity as determined through laboratory 

tests of Great Lake sediments containing complex 

mixtures of environmental contaminants. 

Environmental Monitoring and Assessment 

41:255-289. 

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December 2001 

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Biological Science Report 

4. TITLE AND SUBTITLE 

Toxicity and bioavailability of metals in the Missouri River adjacent to a lead 

refinery 

5. FUNDING NUMBERS 

6. AUTHOR(S) 

Chapman, D.C., A.L. Allert, J.F. Fairchild, T.W. May, C.J. Schmitt, and E.V. 

Callahan 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

U.S. Department of the Interior 

U.S. Geological Survey, Biological Resources Division 

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13. ABSTRACT (Maximum 200 words ) 

This study is an evaluation of the potential environmental impacts of contaminated groundwater from the ASARCO 

metals refining facility adjacent to the Missouri River in Omaha, Nebraska. Surface waters, sediments, and 

sediment pore waters were collected from the Burt-Izard drain, which transects the facility, and from the Missouri 

River adjacent to the facility. Groundwater was also collected from the facility. Waters and sediments were 

analyzed for inorganic contaminants, and the toxicity of the waters was evaluated with the Ceriodaphnia dubia 7-

day test. Concentrations of several elemental contaminants were highly elevated in the groundwater, but not in 

river sediment pore waters. Lead concentrations were moderately elevated in whole sediment at one site, but 

lead concentrations in pore waters were low due to apparent sequestration by acid-volatile sulfides. The 

groundwater sample was highly toxic to C. dubia, causing 100% mortality. Even at the lowest groundwater 

concentration tested (6.25%) C. dubia survival was reduced; however, at that concentration, reproduction was not 

significantly different from upstream porewater reference samples. Sediment pore waters were not toxic, except 

reproduction in pore water collected from one downstream site was somewhat reduced. Th e decrease in 

reproduction could not be attributed to measured elemental contaminants. 

14. SUBJECT TERMS (Keywords) 

Acid-volatile sulfides, arsenic, ASARCO, AVS, brownfields, 

cadmium, Omaha City (Neb.), sediment pore water, SEM 

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