358 (INO-1117-644808) Lead accumulation in invertebrate prey: development of exposure protocols and determination of trophically available fractions.
Start time: 1:50 PM
Inouye, Laura¹, Jones, Robert¹, Yoo, Leslie¹, ¹ USACE-ERDC, Vicksburg, MS, USA
As part of an investigation determining the trophically available fraction of metals in a model terrestrial food chain (invertebrate prey to Western Fence Lizards), we evaluated the ability of several invertebrate prey to bioaccumulate lead and their ability to form metals rich granules, which are hypothesized to be non-available to predators. Crickets (Acheta doemsticus), tenebroid beetle larvae (Tenebrio molitor), and sowbugs (Porcellio scaber) were selected as model prey organisms. A major barrier is the lack of standard exposure methodologies for these species, as each species has particular requirements that create challenges for designing exposure chambers. We were able to devise exposure conditions for all three species that allows for long-term exposure studies. Data for prey organisms indicate that they do accumulate lead from contaminated food, and that a large portion of the accumulated metal is in fractions predicted to be unavailable to predator species.

359 (MCB-1117-844174) Pb Bioaccumulation in Deer Mice: Competition and Antagonism by Co-Occurring Essential Metals in Lab and Field Studies.
Start time: 2:10 PM
McBride, T¹, Reynolds, K², McFarland, C¹, McMurry, S¹, Hooper, M¹, ¹ Texas Tech Universtiy, Lubbock, TX, USA² USFWS, Phoenix, AZ, USA
Our studies of mixed metal and metalloid (As, Cd, Cu, Pb, Zn) exposure in deer mice (Peromyscus maniculatus) at the Anaconda Smelter Site indicated that metal bioavailability of soils contaminated by aerial deposition occurred as a simple linear function of the levels of metals in the soils, though the slope and intercept of the functions were notably lower than anticipated in preliminary risk assessments. Alternatively, metals from former industrial site soils were up to 10 times more available, as evidenced by deer mice carcass concentrations. Further, Pb-induced ALAD inhibition in Anaconda deer mice was reduced compared to similarly exposed laboratory rodents. The co-occurrence of biologically interactive metals in the soil (notably Zn and Cu) potentially influenced these unanticipated findings. To investigate these unexpected findings, we initiated an assortment of regimes with deer mice using both highly bioavailable metals, as well as site-specific soils. Findings from mixed-metal dosing studies are compared and contrasted with those from deer mice dosed with soils collected from specific subsites on the Anaconda Smelter Superfund site, and deer mice captured directly on the studied subsites, to assess the utility of laboratory methods for estimating bioaccumulation and biomarker effects detected in field collected animals. Adult, lab-reared deer mice, exposed to increasing Cu and Zn concentrations, concurrent with effect-inducing Pb exposures, had significantly reduced Pb accumulation in a variety of tissues, suggesting they compete in the uptake mechanisms for Pb. Further, increased Zn, but not Cu, in the diet antagonized Pb's inhibitory effect on ALAD (delta-aminolevulinic acid dehydratase) activity. An initial soil feeding study (3% in food of adult deer mice) indicated that Pb bioaccumulation was approximately 30% compared to Pb-Acetate dosed food at similar concentrations. Further, no differential bioavailability was detected between aerial and industrial sites soils in this initial investigation.

360 (GAN-1117-551675) Mercury concentrations in Salvelinus alpinus from Lake Hazen (Nunavut), effects of size and trophic position.
Start time: 2:30 PM
Gantner, N¹, Koeck, G², Babaluk, J³, Reist, J³, Lockhart, W³, Solomon, K¹, Muir, D^{1, 3}, ¹ University of Guelph, Guelph, Ontario, Canada² University of Innsbruck, Innsbruck, Austria, Austria³ Freshwater Institute, Department of Fisheries and Oceans, Winnipeg, Manitoba, Canada
Arctic char (Salvelinus alpinus), the top predator of High Arctic lakes, is often used as bioindicator of mercury (Hg) contamination in Arctic aquatic ecosystems. Concentrations of Hg in muscle tissues of landlocked char have been shown to exceed the Health Canada Guideline for subsistence consumption (0.20 g g-1 wt weight) in some lakes in the Canadian Arctic. Purpose of this study was to identify effects of size and feeding ecology (trophic position) of Arctic char in Lake Hazen, the most northerly large lake in Canada (81°50′N; 70°25′W), on Hg bioaccumulation and thereby allow better interpretation of temporal trends of Hg contamination. The feeding ecology of the char was identified by analysis of stomach contents and their trophic position measured with stable isotope ¹⁵N and ¹³C signature, revealing three different morphotypes. Total Hg was measured in dorsal muscle tissue. Total Hg concentration was then related to trophic position, size and age of the sampled fish. Temporal trends over a 12 year period (1992 – 2004) for two size classes were identified. Larger individuals (>375mm fork length) with higher ¹⁵N signature (>12) had greater Hg concentrations (THg, 0.24 – 0.78 g g-1 ww) than smaller individuals (<375mm fork length) with lower (<12) ¹⁵N signature (THg, 0.11 – 0.18 g g-1 ww), indicating that feeding ecology (trophic position) plays a key role in causing differences in Hg bioaccumulation. In comparison to feeding ecology and size, age seemed to play a smaller role. Our results from Lake Hazen suggest that future studies monitoring temporal trends of Hg bioaccumulation must be carried out carefully in regard to age, size and trophic position.

361 (PIC-1117-750122) Accumulation of inorganic and organic mercury in phytoplankton and the subsequent trophic transfer to crustaceans.
Start time: 2:50 PM
Pickhardt, P¹, Fisher, N¹, ¹ Stony Brook University, Stony Brook, NY, USA
Phytoplankton concentrate mercury (Hg) from their aqueous surroundings and represent the primary entry point for this toxin to aquatic food webs. Mercury associated with phytoplankton transfers to macrozooplankton and other crustaceans which are consumed by planktivores and subsequently higher trophic levels. Here we used the gamma emitting ²⁰³Hg as either Hg²⁺ or CH₃Hg⁺ to test for the effects of different phytoplankton species on Hg accumulation dynamics in two natural waters containing significantly different concentrations of dissolved organic carbon (DOC). Additionally, we fed phytoplankton exposed previously to either Hg²⁺ or CH₃Hg⁺ to Daphnia pulex in both water types. After 24 h of exposure to aqueous Hg, volume concentration factors (VCFs) for Hg²⁺ in the 4 cells types used were similar across the two waters, but varied significantly across species. However, for CH₃Hg⁺, VCFs at 24 h for 3 of the 4 cell types concentrated more Hg in the water with the higher DOC concentrations, but VCFs were generally similar across phytoplankton species. Likewise, Daphnia pulex accumulated more Hg²⁺ and CH₃Hg⁺ from diatoms exposed to Hg in the high DOC water implicating high DOC with more efficient trophic transfer of Hg.

(58186) Break.
Start time: 3:10 PM

362 (AAA-1117-096848) Influences of Cd and Ag co-exposure on their uptake kinetics in green mussels.
Start time: 3:50 PM
Ng, T.¹, Wang, W.-X.¹, ¹ The Hong Kong University of Science & Technology, Hong Kong, China
Metal accumulation in co-exposure may be different from that in single exposure because metals compete for ligands during uptake or storage for detoxification. In this study, we determined how the co-exposure of Ag and Cd modified the corresponding metal uptake physiology and the subcellular distribution in the green mussels. The Cd assimilation efficiency was enhanced in the single Cd or Ag+Cd co-exposure after 4 weeks, but the enhancement was not influenced by Ag. There was an apparent interaction between Ag and Cd co-exposure on the dissolved uptake of both metals, but the interaction was dependent on the exposure period and the metal concentration. Ag exposure reduced the effects of Cd exposure on Cd dissolved uptake and vice versa for Cd exposure on the dissolved uptake of Ag. Metal interaction was more evident in the subcellular metal distribution. A much higher fraction of Ag was associated with the metallothionein-like protein (MTLP) in the Ag+Cd co-exposed mussels as compared to those only exposed to Ag, suggesting that Ag may displace Cd from MTLP that has a higher binding capacity with MTLP. Generally, our results imply an immediate interaction on the dissolved uptake of metals and a modification of subcellular metal distribution after metal co-exposure.

363 (VOI-1117-198945) Metal uptake by earthworms in different soils.
Start time: 4:10 PM
Voigt, A¹, Lanno, R¹, ¹ The Ohio State University, Department of Entomology, Columbus, OH, USA
Soil characteristics, such as pH and organic matter content, can influence environmental metal availability, and hence metal bioavailability to terrestrial organisms. Earthworms are important indicator organisms for assessing metal bioavailability in soil systems. Bioaccumulation studies were designed to study metal uptake and depuration kinetics in earthworms (Eisenia andrei) as influenced by soil characteristics. Five soils differing in pH, texture and organic matter content were spiked with As, Cd, Pb, or Zn. Earthworms were exposed to metal spiked soils for 2, 4, 8, 16, 32 or 64 days. To examine the depuration kinetics some earthworms were transferred on day 32 into unspiked soil, and these worms were sampled on day 2, 4, 8, 16, or 32 after the transfer. Estimates for environmental metal availability were based upon metal levels dissolved in different weak salt soil extracts or estimated free metal activities in soil solution. The fractionation procedure of Lanno et al. (2002) was applied to examine the uptake and depuration kinetics of the benign and toxicologically bioavailable metal fractions in earthworms. Total metal body burdens and metal levels in various fractions were determined by ICP-OES. The effects of soil physical and chemical properties on metal bioaccumulation kinetics will be discussed.

364 (GAL-1117-863133) Tree Swallows nesting in Calumet, IL as an indicator of contaminant transfer from aquatic to terrestrial systems.
Start time: 4:30 PM
Gallo, S^{1, 2}, Levengood, J¹, Soucek, D¹, Hill, W¹, Talbot, J³, Bordson, G³, ¹ Illinois Natural History Survey, Champaign, IL, USA² University of Illinois at Urbana-Champaign, Champaign, IL, USA³ Illinois Waste Management and Research Center, Champaign, IL, USA
Tree Swallows (Tachycineta bicolor) nesting near wetlands are widely recognized as useful biomonitors of sediment contaminants due to their tolerance of contaminants and their tendency to feed on emergent aquatic insects. We studied Tree Swallows nesting at two contaminated wetlands and one reference site in the highly industrialized Calumet region of Chicago, Illinois, to evaluate potential impacts from trophic transfer of contaminants from sediments and emergent aquatic insects. Total mean mercury levels in Tree Swallow eggs varied significantly by site ranging from 112 to 232 ppb dry weight, with similar levels in nestlings. Egg mercury levels were positively correlated with nest initiation date (r = 0.73861, p<0.0001) and negatively correlated with brood size (r =-0.54446, p=0.0009) across all sites. Generally, mean aquatic insect metal concentrations at the sites are much higher than the mean metal concentrations in both the swallow nestlings and eggs, with lead, manganese and iron being an order of magnitude higher. Copper levels in the emergent aquatic insects were 2 to 5 times higher than eggs and nestlings, with values between 19 to 30 ppm dry weight. Isotope analysis and additional diet analysis will be employed to quantify the difference between expected and observed concentrations in trophic levels.

365 (ROS-1117-822076) Relating copper bioaccumulation and toxicity in marine invertebrate larvae for seawater Biotic Ligand Model development.
Start time: 4:50 PM
Rosen, G¹, Rivera-Duarte, I¹, Chadwick, D¹, Zacharias, C², Santore, R³, Paquin, P³, ¹ Space and Naval Warfare Systems Center San Diego, San Diego, CA, USA² Computer Sciences Corporation, San Diego, CA, USA³ HydroQual, Inc., Camillus, NY, USA
The Biotic Ligand Model (BLM) has proven to be a useful tool in the development of site-specific water quality criteria for metals in freshwater environments by using easy to measure chemical characteristics of the water body as opposed to generation of more costly and time consuming toxicity data. It also shows promise for application in seawater; however, its demonstration in the marine environment is relatively limited. In this study, calibration data were developed for a seawater-based BLM by relating tissue accumulation data with associated toxicity in spiked, multi-concentration exposures with copper using larvae of two highly relevant marine invertebrates. Mytilus galloprovincialis (Mediterranean mussel) and Strongylocentrotus purpuratus (purple sea urchin) larvae are very sensitive to copper and are key drivers in the derivation of USEPA ambient water quality criteria for copper in saltwater. It is anticipated that this data will help validate assumptions currently made by the traditional fish gill-based BLM. The effects of differing chemical characteristics (e.g. dissolved organic carbon) on accumulation and toxicity of copper, by way of exposures with seawater samples of different origin, will also be presented.

366 (PAQ-1117-553271) Development of a physiologically-based pharmacokinetic (PBPK) model for metal bioaccumulation by bivalves.
Start time: 5:10 PM
Paquin, P.¹, Mathew, R.¹, Salazar, M.², Salazar, S.², Damiani, D.³, Dwyer, R.⁴, Farley, K.^{1, 5}, Santore, R.⁶, Di Toro, D.^{1, 7}, ¹ HydroQual Inc., Mahwah, NJ, 07430² Applied Biomonitoring, Kirkland, WA, USA³ US ACOE, NY, NY, USA⁴ International Copper Association, NY, NY, USA⁵ Manhattan College, Bronx, NY, USA⁶ HydroQual Inc., Camillus, NY, USA⁷ University of Delaware, Newark, DE, USA
A physiologically-based pharmacokinetic (PBPK) model of metal accumulation is being developed. An important objective of this effort is that the model be useful in predicting not only accumulation levels that result from combined waterborne and dietary routes of exposure to metals, but also effects. Efforts to date have focused on development of a model of copper metabolism by bivalves. The model includes uptake of dissolved copper from the water to the hemolymph via exchange across the gill and mantle, and uptake of sorbed copper from food to the hemolymph via the digestive gland. Copper is circulated to the other organs via the hemolymph. Losses of copper occur via diffusive exchange at the gill and mantle, and via renal and fecal excretion. Previous phases of this project have been directed at the development of ways to represent essential metal regulation and intracellular speciation (e.g., induction of metallothionein synthesis to simulate metal detoxification and interaction with metal-sensitive enzymes). The current status of development efforts will be reviewed, including model structure, model formulation, and an example application to data. The future direction of model development efforts will also be discussed.