718 (AND-1117-578329) The influence of seasonal variations on the distributions of bioavailable PCBs and OC pesticides by using passive sampling devices in the Willamette River, Oregon.
Start time: 1:50 PM
Sethajintanin, D¹, Anderson, K¹, Grove, R², ¹ Oregon State University, Corvallis, OR, USA² USGS, Corvallis, OR, USA
Although the distributions of organochlorine compounds have been well investigated worldwide, very few studies have actually investigated the temporal transport of their bioavailable fraction which is more relevant to their toxicity, mobility and degradation processes. The present study focused on the spatial and temporal occurrence of bioavailable organochlorine pesticides and polychlorinated biphenyls (PCBs) within the surface water of a contaminated harbor to promote a more complete understanding of organochlorine contamination characteristics. Semipermeable membrane devices (SPMDs) were intensively deployed within the main river adjacent to various land uses of the lower Willamette River, Oregon including Portland Harbor superfund site in summer and fall during 2001-2004. An increase of estimated bioavailable DDTs (sum of p,p′-DDT, p,p′-DDD, and p,p′-DDE) concentrations was strongly affected by the local historic productions of DDTs and seasonal changes in river conditions. The dominance of bioavailable p,p′-DDD and high p,p′-DDD: p,p′-DDE ratios observed during periods of low precipitation, low river flow suggest direct inputs of p,p′-DDD and possible favoring conditions for reductive dechlorination of p,p′-DDT to p,p′-DDD. The estimated bioavailable concentrations and daily loads of PCBs and dieldrin increased during periods of high precipitation, high river flow, especially during episodic rainstorms. Similarity of PCB congener profiles and PCB homolog ratios at the industrial area and at the urban/residential area suggests the local sources of PCBs at the industrial area are important enough to significantly increase the concentrations of bioavailable PCBs in surface water but not to substantially change composition relative to surface water inputs from upstream. In addition, seasonal exceedances of the bioavailable organochlorine concentrations over the national and the Oregon water quality criteria suggest the potential impacts associated with seasonal changes of bioavailable organochlorine distributions in surface waters and the significances of consideration of realistic temporal and site-specific conditions in risk assessment and water quality management.

719 (HIL-1117-579256) Seasonal and source influences on labile metal distribution within the lower Willamette River, Oregon.
Start time: 2:10 PM
Hillwalker, W¹, Grove, R², Anderson, K¹, ¹ Oregon State University, Corvallis, OR, USA² USGS, Corvallis, OR, USA
The Willamette is a major river in Oregon utilized for transportation, recreation, subsistence fishing and aquatic organism habitat. The lower Willamette River is a typical urban and industrial lotic system with historical and current input of persistent organic pollutants and heavy metals. Though discrete sampling methods (e.g. grab water) are customarily required for assessment of pollutant risk to the principle users of an impacted site, this sampling methodology lacks the ability to capture time-integrated profiles and/or pulses of bioavailable contaminant fluxes in lotic systems. Diffusive gradients in thin film (DGT) is an in situ, time-integrated sampling device for the measurement of labile, cationic metal species in solutions at environmentally relevant concentration levels. DGT samplers were used to evaluate seasonal and spatial influences on the distribution of labile metals in the lower Willamette River, OR, during 2003 and 2004. The areas assessed include the Portland Harbor (RM 3.5 to 9.5) and the McCormick and Baxter (RM 7 east) Superfund sites. DGT were deployed for up to 21 days within the river near urban, industrial and undeveloped land use areas during a range of seasonal river conditions. Site-specific factors and metal-specific chemistry influenced the variability and distribution of labile metal concentrations seasonally and spatially within the lower Willamette River. The outcome of this study introduces uncertainty of interpreting grab water data and reevaluating the selection of sampling protocols when assessing contaminant risk within lotic systems.

720 (WOR-1117-648482) Effects of water chemistry on nickel biouptake by the green alga, Chlamydomonas reinhardtii.
Start time: 2:30 PM
Worms, I¹, Wilkinson, K¹, ¹ Analytical and Biophysical Environmental Chemistry (CABE), Geneva, Switzerland
It is well known that the bioavailability of dissolved trace metals depends on many physico-chemical parameters including the temperature, pH, ionic strength of the water, etc.... Among other important parameters, the presence of ligands and major cations (Ca²⁺, Mg²⁺) has an important influence on biological responses to trace metals. Analytical chemistry has provided some responses, especially concerning the speciation of these pollutants in natural aquatic systems, but no general tool is available to evaluate trace metal bioavailability to aquatic organisms. Furthermore, no clear (fundamental) response to the question –what species in the media is controlling the biouptake process– has been proposed thus far. Based on the assumption that biological effects occurs when metals interact with intracellular components, we have determined short-term internalisation fluxes (J_int, mol cm^-2 s^-1 ) as an indicator of acute toxicity. The work demonstrates that Ni bioaccumulation is a steady-state process that can be best predicted by measuring equilibrium species of Ni in solution and by taking into account the quantitative interaction of competing ions for metal transport sites. In addition to providing greater insight into the mechanisms controlling the bioavailability of nickel to Chlamydomonas reinhardtii, the results allowed us to conclude that nickel biouptake was best predicted on the basis of the free ion activity (FIAM) or biotic ligand (BLM) models.

721 (TRI-1117-727466) A Chemical Approach for Assessing the Bioavailability of PCBs From Sediment.
Start time: 2:50 PM
Trimble, T, Lydy, M,
In order to accurately evaluate the risks posed by widespread PCB contamination, the degree of bioaccumulation in sediment-dwelling organisms must be determined. Although direct exposure experiments have commonly been conducted in the past to determine the bioavailability of contaminants from sediment to biota, a chemical method of determining bioavailability would be less expensive and less laborious. This study assesses the Tenax chemical extraction technique for determining bioavailability of PCBs from sediment and compares it to BSAFs (biota-sediment accumulation factors) determined using live organisms. The Tenax method will be evaluated for accuracy and predictability using a range of sediment types with differing organic carbon contents and sediment characteristics. Initial BSAFs from bioassays appear to be dependent on organic carbon (OC) content, with sediment containing approximately 150 ppb PCBs and 0.9% OC yielding a BSAF of 2.88 for total PCBs in Lumbriculus variegatus. Additional sediment BSAF data and Tenax bead results will be presented, with the majority of desorption to Tenax anticipated to occur within 6-10 hrs of contact with sediment.

(58364) Break.
Start time: 3:10 PM

722 (JEN-1118-273002) Metal bioavailability and potential toxicity in sediments adjacent to a former cable manufacturing facility.
Start time: 3:50 PM
Jenkins, K¹, Beardsley, K², Bartee, M³, Huntley, S¹, Kiehl-Simpson, C⁴, ¹ BBL, Inc., Petaluma, CA, USA² BBL, Inc., Walnut Creek, CA, USA³ BBL, Inc., Carpenteria, CA, USA⁴ Parsons Engineering Science, Inc., Williamsville, NY, USA
A study was conducted to evaluate site-specific bioavailabity and potential toxicity of metals in sediments adjacent to a former copper cable manufacturing facility on the Lower Hudson River. Due to the nature of historical operations, copper was the metal of primary interest. Surficial sediment samples were collected at 17 locations where previous sampling had demonstrated elevated concentrations of total metals. Bulk sediment samples were analyzed for total metals, redox potential, total organic carbon (TOC), acid volatile sulfides (AVS) and simultaneously extracted metals (SEM). Porewater was extracted and analyzed for total and dissolved metal concentrations, and dissolved organic carbon (DOC). Specific methods employed in this study are detailed in a separate presentation. Metals concentrations in bulk sediments were within the range of previously reported data. AVS concentrations were high and exceeded SEM concentrations of cadmium, copper, nickel, lead, and zinc at all locations (SEM-AVS ranged from -7.7 to -72.2) indicating that these metals should not be bioavailable or toxic to aquatic organisms. Concentrations of TOC in bulk sediments and DOC in porewater provide additional capacity to reduce metal bioavailabity and toxicity. Concentrations of metals in pore water were in the low ppb range. These data were compared against chronic marine ambient water quality criteria (AWQC). In addition, site-specific chronic marine AWQC for copper were developed based on DOC concentrations in porewater. Taken together these independent lines of evidence indicate that the concentrations of AVS in sediments and DOC in porewater are more than sufficient to limit metal bioavailability and prevent metal toxicity in these sediments.

723 (LAT-1117-824132) Calculation of a Water-Effects Ratio for Aluminum in Solutions of Different pH.
Start time: 4:10 PM
Latimer, H¹, Bearr, J¹, Bowersox, M¹, Diamond, J¹, ¹ Tetra Tech, Inc., Owings Mills, Maryland, USA
An acute Water-Effect Ratio (WER) study was completed for aluminum in effluent from a drinking water treatment plant in western Maryland. The study approach used was modeled on EPAs 2001-streamlined copper WER procedure. Two paired sets of acute tests were conducted using Ceriodaphnia dubia and Pimephales promelas (fathead minnow). Tests were conducted in site water (pH 7.5 and hardness 80 ppm) and laboratory water (pH 6.5 and hardness 10 ppm). The laboratory water was selected to mimic that used in the studies upon which EPAs 1988 chronic aluminum criterion (0.087 ppm) is based. These tests resulted in a mean final WER of 2.73 for C. dubia and 6.87 for fathead minnow. The larger WER generated by the less sensitive species (fathead minnow) is contrary to EPAs 1994 WER guidance which suggested use of the most sensitive species would yield the highest WER value. Based on an extensive review of the literature conducted in conjunction with this study, we expected that the sensitivity of fish to aluminum would increase more rapidly than that of C. dubia in response to a change in pH. As expected, the difference in pH between the effluent and the synthetic laboratory water resulted in a greater difference in aluminum toxicity to fish than to C. dubia. Although hardness is also thought to mediate aluminum toxicity, the literature is less clear on the effects of hardness on aluminum toxicity while substantial evidence suggests important pH-related effects. Further testing will be necessary to explore the effects of hardness on aluminum toxicity. These results indicate that the abbreviated testing scheme developed for calculation of copper WERs (requires only two sets of paired tests) is appropriate for use with aluminum, however both a fish and invertebrate test species should be used for aluminum WER calculation.

724 (GUS-1117-820869) Do Contaminant Mixtures Alter Contaminant Bioavailability?
Start time: 4:30 PM
Gust, K¹, ¹ Louisiana State University, Baton Rouge, LA, USA
Although individual models developed to assess metal or hydrocarbon bioavailability in sediments (i.e. SEM-AVS relationships or equilibrium partitioning theory respectively) generally provide accurate determinations of contaminant bioavailability for each individual class of contaminants, effects of metal-hydrocarbon mixtures on model predictions have not been tested. Sediment bioassays were conducted to investigate effects of PAH on physical-chemical parameters indicative of metal bioavailability including: SEM-AVS relationships, sediment pH and dissolved metal concentrations in porewater and overlying water. As well, metal effects on PAH bioavailability were tested using biota-sediment accumulation factor (BSAF). To determine if the above parameters provided accurate estimates of contaminant bioavailability, both PAH effects on metal bioaccumulation and toxicity and metal effects on PAH bioaccumulation and toxicity were tested. The PAH phenanthrene (Phen) and the toxic metal Cd were used as model contaminants. Results indicated Phen had no affect on SEM-AVS relationships or sediment pH and had marginal effects on Cd concentrations in both overlying water and porewater. However, in sediment exposures, Phen dramatically increased Cd bioaccumulation and lethality in the freshwater amphipod Hyalella azteca. Conversely, Phen reduced Cd bioaccumulation in the freshwater tubificid oligochaete Ilyodrilus templetoni thereby reducing lethality in sediment exposures. Effects in each species resulted from Phen-mediated effects on Cd bioaccumulation via sediment feeding. Cadmium had no effect on BSAF for Phen, Phen bioaccumulation or Phen toxicity in I. templetoni and similar effects are suggested to have occurred in H. azteca. Based on these results, BSAF appears to be an accurate indicator of PAH bioavailability regardless of the presence of metal. However, although the physical-chemical parameters used as surrogate measures of metal bioavailability were not affected by PAH, PAH-mediated effects on metal bioaccumulation via feeding were observed in test organisms and these effects were species specific. Therefore, sublethal effects of hydrocarbons in metal-hydrocarbon mixtures may render standard measures of metal bioavailability inaccurate.

725 (YOU-1117-237577) Chemical Approaches for Assessing Bioavailability of Hydrophobic Contaminants in Sediment.
Start time: 4:50 PM
You, J¹, Landrum, P², Lydy, M¹, ¹ Southern Illinois University, Carbondale, IL, USA² NOAA, Great Lakes Environmental Research Lab, Ann Arbor, MI, USA
To address the bioavailability of hydrophobic contaminants in sediment, biota-sediment accumulation factors (BSAF) are usually calculated using tedious and expensive bioassays. Due to the existence of resistant, slowly reversible, binding compartments within the sediment matrix, bioaccumulation of contaminants from sediment can not be directly estimated from their total concentrations in sediment, but should be better estimated from contaminant concentrations in the pore water or the rapidly desorbing fraction from sediment. Therefore, two chemical approaches, the determination of rapidly desorbing fraction with tenax absorbent and the determination of pore water concentration with matrix solid phase microextraction (M-SPME), were evaluated as alternatives for assessing bioavailability of five hydrophobic contaminants with different characteristics (2,2^,,4,4^,,5,5^,-hexachlorobiphenyl, permethrin, DDE, phenathrene and chloropyrifos) in sediments with different organic carbon contents. The results were also compared to the BSAF measured directly from 14-day and 28-day oligochaete Lumbriculus variegatus bioaccumulation tests. After a 7-day aging period, sediments spiked with 14C-labelled compounds were tested using tenax absorbent, SPME fiber and L. variegatus. The possibility and accuracy of the rapidly desorbing fraction measured from the tenax approach, and pore water concentration detected from the M-SPME approach for predicting BSAF values were evaluated for the five target compounds and the correlation of rapidly desorbing fraction and pore water concentration with Kow of chemicals and organic carbon in sediment were also examined. The relative costs of the different approaches were also compared.

726 (LEW-1117-833415) Temporal and Spatial Variability of Free Ion Copper in Boston Harbor.
Start time: 5:10 PM
Lewis, Christopher¹, Shine, James¹, Coull, Brent¹, ¹ Harvard School of Public Health, Boston, MA, USA
With developing regulatory focus on the use of Total Maximum Daily Load models (TMDLs) and the Biotic Ligand Model (BLM), there is a need to understand the temporal and spatial variability of parameters used as inputs into these models. For example, the free metal ion concentration, a cornerstone of the BLM, may have substantial temporal and spatial variability that must be quantified before a BLM-based water quality criterion can be implemented. A field-based study was conducted to quantify the role of space and time in the variance of free ion Cu concentrations measured in Boston Harbor, using the recently developed field-deployable version of the Gellyfish Sampler, an equilibrium-based sampler that measures free ion concentration. In addition to estimated free ion Cu concentrations, a host of other aquatic chemical parameters were measured, including DOC, POC, Chl-a, total dissolved and particulate Cu, and salinity and temperature. A general linear model with mixed effects, using random spatial and temporal effects was used to quantify the contributions of space and time to the total estimates of the variance. In addition, using regression analyses, aquatic chemical parameters were tested as predictors of free ion concentration.