WP20 Contaminated Harbor and River Sediment|
Wednesday, 16 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall
WP208 (HWA-1117-853307) Historical trends of organic contaminants and trace metals in salt marsh, San Francisco Bay, California.
Start time: 8:00 AM
Hwang, H-M1, Green, PG1, Young, TM1, 1 University of California, Davis, CA, USA
Many regulatory actions have reduced input of contaminants from point-sources and consequently environmental quality has been enhanced significantly. However, continuous growth in population especially in urban areas may induce increased input of contaminants from non-point sources, resulting in slowed progress toward the clean environment. Historical trends of regional water quality can be revealed by chemical analyses of contaminants in sediment core. Hydrophobic organic chemicals and metals in the water column generally tend to be adsorbed onto particulate materials and then find their way in the sediment as a sink. As a result, sedimentary levels of contaminants can represent overall water quality. Sediment cores were collected from Stege Marsh, San Francisco Bay, California, to investigate the historical input of organic contaminants (PAHs, PCBs, and organochlorine pesticides) and trace metals. Depth profiles indicated that the degradation of water quality had been started since the 1940s and 1950s and continued until the 1970s when the use of PCBs, DDT, and leaded gasoline was peaked. Sedimentary levels of contaminants provide evidences that water quality has been enhanced after the use of these contaminants was banned and restricted. Though, effects range-median quotients in surface sediments are 5 times lower compared to sediments deposited in the 1970s, concentrations of contaminants in surface sediments are still higher than sediment quality guidelines. PCB congener patterns revealed that PCB 1248 was a predominant source. PAH distribution patterns and some PAH ratios indicate PAHs from gasoline and diesel combustion were the major sources. Iron normalized lead concentrations are decreasing continuously after leaded gasoline was phased out. Iron normalized zinc concentrations were the highest at the deepest section (55 - 60 cm) and exhibited continuous decreasing pattern towards the surface. Though nickel concentrations were higher than sediment quality guidelines, iron normalized enrichment factor confirms that Bay area terrestrial soils contain elevated levels of naturally originated nickel.
WP209 (DAV-1118-097024) Use of a numerical model to predict transport and flux of fecal bacteria in a river.
Start time: 8:00 AM
Davis, III, J1, Hines, T1, Brew, J1, Sharpe, L1, Byl, T1, 2, 1 Tennessee State University, Nashville, TN, USA2 USGS, Nashville, TN, USA
Fecal pollution in surface waters is a serious water-quality problem. As a result, scientists have developed a number of models in an attempt to predict the fate and transport of fecal pollution in riverine systems. Various models predict the rate of bacteria removal from the water column based on density, settling rates and water velocity. Such models, however, do not consider survival and reproduction of bacteria in sediments, or re-suspension. Flume and stream experiments were conducted to measure the survival, reproduction, and resuspension of fecal bacteria in sediments. These results can be used to modify a numerical model by incorporating survival of bacteria in bed sediments and re-suspension into the water column, in addition to other parameters such as water velocity, initial bacteria concentration, and settling rate. Fecal coliform bacteria were introduced into the circulating-water flume at known concentrations and monitored as they settled or remained suspended. Bacteria concentrations were measured in the water column and the sediment along the flume to determine bacterial fate and transport. The model accurately predicted bacteria settling from the water column. The sediment fecal bacteria population declined at an exponential rate over several weeks (experimental decay value = -0.2735). This decomposition rate was coupled to the numerical model, and additional tests were done in a small stream contaminated with fecal coliform. Comparison of the model and stream data were mixed due to irregular resuspension of bacteria-contaminated sediments. Additional work was done to incorporate resuspension as a function of water velocity, particle size and density into the formula.
WP210 (ZIE-1117-826096) Development of a whole sediment toxicity identification and evaluation (TIE) for estuarine sediments.
Start time: 8:00 AM
Ziegler, G1, Fisher, D1, Osbourne, M1, Klosterhaus, S2, Baker, J2, 1 University of Maryland Wye Research and Education Center, Queenstown, Maryland, USA2 University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, Maryland, USA
Toxicity identification evaluation (TIE) methods have been used to identify toxicants in interstitial water samples extracted from contaminated sediments. More recently a marine whole sediment TIE has been developed by the U.S. Environmental Protection Agency to test the whole sediment matrix avoiding concerns around interstitial water TIEs with a more realistic mode of exposure. These TIE methods have been described for evaluating marine sediments with the amphipod Ampelisca abdita, however these are limited to salinities greater than 20 ‰. Here we describe whole sediment TIE methods for use with an estuarine amphipod, Leptocheirus plumulosus. The efficacy of these methods was tested using estuarine sediments spiked with representative compounds from three classes of toxicants: ammonia, metals and nonpolar organics. Resins or powdered coconut charcoal (PCC) were combined with spiked sediments and left for 24 h followed by a 7 d amphipod exposure. A dilution series of metals spiked sediment (0-4,000 mg/kg total of 5 metals) was treated with a chelating resin SIR-300HP while ammonia (750 mg/kg NH4Cl) and endosulfan (12.5mg/kg) spiked sediments were treated with SIR-600 (zeolite) and TOG-CA (PCC) respectively. Controls containing un-spiked sediment and resin or PCC had high survival (>90%) for all manipulations. Reduction in toxicity was observed for each class of toxicants when treated with the appropriate compound and compared to un-manipulated sediment. In several cases emeliorative effects were observed where several manipulations decreased toxicity at one of the toxicant dilutions. Work continues to demonstrate the usefulness of these methods with environmentally contaminated sediments.
WP211 (WAR-1117-829361) Predicting metal bioavailability and toxicity in stream bank samples.
Start time: 8:00 AM
Ward, T.1, Sharma, M.1, Kim, G.1, Saxe, J.1, 1 Gradient Corporation, Cambridge, MA, USA
During a focused screening level ecological risk assessment, samples were collected in and around several small streams that traversed an undeveloped floodplain forest adjacent to an industrial site. Locations were classified as either sediment or soil based on the results of a habitat assessment and wetland delineation study. Samples were collected along transects that were established perpendicular to the streams - one in the center of the stream, one from each stream bank just above the high water mark (overbank), and one a few meters from each edge of the stream. Overbank samples generally contained higher concentrations of metals and had a higher silt/clay content than did the sediment samples collected in the streams or the soil samples collected several meters from the streams. The overbank samples could be classified as soil as the result of their location above the water, however, these sample locations could also be classified as sediments because they would be submerged during periods of flooding, potentially liberating particle-bound metals. Predicting metal bioavailability and toxicity from the overbank samples was further complicated by the fact that during a period of brief submergence, equilibrium conditions would be unlikely. Additionally, because the overbank samples were not submerged at the time of sampling, pore water analysis was not possible. For the risk assessment, overbank samples were treated both as soils (compared to soil benchmark values and evaluated using food web models) and as sediments, taking into consideration total organic carbon (TOC) concentrations and AVS/SEM ratios. Although the AVS/SEM procedure was not designed for use in soil, and, as expected, no appreciable concentrations of AVS were present in these samples, the SEM analysis did identify those metals likely to be mobilized if the overbank becomes submerged (a fraction of the total). In addition, knowing the concentration of TOC allowed us to predict a lack of bioavailability during submergence.
WP212 (GOD-1117-833226) Analysis of imposex in neogastropods collected from the Lower Duwamish Waterway.
Start time: 8:00 AM
Godtfredsen, K1, Hotchkiss, D2, Williston, D3, Stern, J3, Fox, S4, Goldberg, J5, Andersen, H1, Kohn, A6, 1 Windward Environmental, Seattle, WA, USA2 Port of Seattle, Seattle, WA, USA3 King County, Seattle, WA, USA4 The Boeing Company, Seattle, WA, USA5 City of Seattle, Seattle, WA, USA6 University of Washington, Seattle, WA, USA
The Lower Duwamish Waterway (LDW), located in Seattle, Washington, was added to the National Priorities List (Superfund) in September 2001. Tributyltin (TBT) was identified as a chemical of potential concern for benthic invertebrates in the Phase 1 Ecological Risk Assessment (ERA). Of the benthic invertebrates that inhabit the LDW, neo- and mesogastropods have been identified as particularly sensitive to TBT. Exposure to TBT can result in the development of male sexual organs in females in some neo- and mesogastropod species (a condition known as imposex). If sufficiently pronounced, imposex can interfere with gastropod reproduction and potentially result in population-level effects. As part of the ERA, gastropods were collected in August 2004 from the LDW to directly assess imposex at locations with TBT sediment concentrations ranging from 34 to 358 g/kg dw. Imposex stage and relative penis size (RPS) of the two most abundant neogastropods, Nassarius mendicus and Astyris gausapata, were determined. Of the 24 N. mendicus examined, 14 were male and 10 were female. All N. mendicus females had developed imposex at a stage that would not likely interfere with their ability to reproduce (RPS: 0.2 to 1.8 percent). Of the 14 A. gausapata examined, none of the 10 females had developed imposex. Additional sampling of gastropods and imposex analyses will be conducted in August 2005.
WP213 (MAR-1117-837027) Important Considerations when Evaluating the Ecotoxicty of Speciating Metals in Sediments.
Start time: 8:00 AM
Martello, L.1, Wenning, R.1, Sorensen, M.2, 1 ENVIRON International Corp., Emeryville, CA, USA2 ENVIRON International Corp., Atlanta, GA, USA
Quantifying the toxicity of metals in sediments is complicated by the fact that metals speciate. The speciation of metals in aqueous environments is determined by the geochemistry of the media, which affects metal mobility, bioavailability, and toxicity. Considerations for risk assessment of speciated metals that need to be addressed when evaluating ecotoxicity are reviewed. Chromium illustrates several key considerations. Chromium occurs in sediments in two oxidation states, Cr3+ and Cr6+. Cr6+ is very soluble and highly toxic, while Cr3+ generally has low solubility and toxicity. Therefore, identifying the specific species of chromium in sediments characterizes the potential toxicity to benthic organisms far better than a measure of total chromium. Still, sediment quality guidelines typically combine both oxidation states as total chromium for quantifying ecotoxicity. Several studies illustrate the deficiency in using total chromium to assess risk based on the lack of correlation between total chromium and sediment toxicity. These studies suggest that if acid volatile sulfides are present, (1) the sediments exhibit reducing conditions, and (2) chromium will exist in the nontoxic trivalent form. In reducing conditions, Cr6+ is readily speciated to Cr3+ by sulfides, ferrous iron, and organic reductants. Oxidation/reduction cycling of iron and sulfur is driven by microbial respiration, which leads to Cr6+ reduction to Cr3+. Organic matter mediates chromium toxicity through the formation of sediment organic matter-chromium complexes that reduce chromium bioavailability. Even high levels of contamination may be of little or no biological significance if bioavailability is limited. In summary, the dissolved fraction of chromium better represents the biologically active, or bioavailable, portion of the metal than the total fraction. Models used to predict contaminant concentrations in sediment based solely on total metals are inadequate.
WP214 (MOR-1117-841112) Responses of Five Benthic Organisms to Marine Sediments from Former Operating Pulp Mills.
Start time: 8:00 AM
Mortensen, L1, Hummell, R1, 1 Malcolm Pirnie, Seattle, WA, USA
Marine sediments near previously operating pulp mills in Sitka, Alaska and Port Angeles, Washington were evaluated for benthic toxicity. Multiple laboratory bioassays were used as part of these evaluations. Subchronic toxicity measured by survival over 10 days was evaluated and observed in the amphipod Rhepoxynius abronius. Chronic toxicity measured by survival for 28 days, and reproductive success were evaluated, but not observed in L. plumulosus. Myitilus edulis larvae were evaluated for survival and developmental normality and effects were observed near the mill. Chronic effects of Neanthes arenaceodentata were evaluated based on growth of the polycheate for 28 days. Reduced growth was observed. Echinoderm larvae (Strongylocentrus purpatus) development was also evaluated using a suspended phase test to assess the effects of colloidal and very fine particulate material on pelagic organisms in the water column. During these tests, a slurry of the sediment was created, and the organisms were exposed to water columns containing 10%, 50%, and 100% suspended phase particulates. Reduced development was observed at exposures to 50% and 100% suspended phase particulate exposure. Several persistent organic pollutants were detected in the sediments evaluated. Additionally, toxic effects were generally observed in the depositional areas near these facilities where organic carbon levels had been increased significantly, and ammonia concentrations evaluated during the tests were a significant cause of some of the observed mortality. Degradation of wood debris in the marine environment also produced levels of resin acids, guiacols, and phenols that were associated with much of the observed mortality after the influence of ammonia was removed. The relationship of chemical concentrations in the test sediments and the bioassay results is presented with a correlation analyses.
WP215 (GOM-1117-811357) Aerobic Transformation of Polychlorinated Biphenyls by Microorganisms Isolated from Sediments of the San Jose Lagoon.
Start time: 8:00 AM
Gomez-Alvarez, V1, 2, Toranzos, G2, 1 University of Massachusetts, Amherst, MA, USA2 University of Puerto Rico, San Juan, PR, USA
Polychlorinated biphenyl compounds (PCBs) are distributed worldwide, and in many cases sediments act as ultimate sinks for this man-made pollutant. PCBs have captivated concern because of their persistence and possible health effects. Little is known about the PCB-utilizing microbial communities in tropical sediments. The objectives of this project were: (i) isolate and enumerate aerobic bacteria capable of transforming PCBs from sediments of the San Jose lagoon (Puerto Rico), (ii) determine their PCB-degradative competence, and (iii) measure the transformation of PCBs by mixed bacterial communities using sediment microcosms. An understanding of the biodegradative capacity of populations by individual bacteria as well as communities of bacteria is important in understanding PCB's biodegradation in tropical environments. DNA-DNA hybridization determined the presence of PCB-degrading gene in our sediments. Furthermore, less than 0.000001% of the total recoverable aerobic bacterial populations were biphenyl-degrading. Indigenous aerobic bacteria capable of transforming PCBs were isolated using biphenyl enrichment cultures. PCBs have been shown to be co-metabolized by the microbiota when biphenyl is present. Six isolates were selected to determinate PCB-degrading competence of a mixture of six congeners and Aroclor 1248. All isolates transformed the detectable mono-, di-, and trichlorobiphenyls and most of the tetra- and pentachlorobiphenyls. Microcosm assays demonstrated the abilities of the indigenous microbiota of the sediment amended with biphenyl to transform several congeners of PCBs in sediments. The lower-substituted congeners were degraded more rapidly and congeners with the same amount of chlorine were transformed at different rates. Variations in microbial communities during biodegradation of PCBs were monitored using carbon source profiles. Principal Component Analysis revealed a distinction between disturbed (PCBs) and undisturbed sediment samples. PCBs may affect the physiological diversity of the communities. In conclusion the indigenous tropical microbiota may have the potential to degrade PCBs present in the lagoon sediments.
WP216 (LET-1117-816234) Polybrominated diphenyl ethers, including decabromodiphenyl ether (BDE 209), and tetrabromobisphenol-A (TBBPA) and degradation products in sediments from Lake Erie.
Start time: 8:00 AM
Chu, S.1, Shahmiri, S.2, Haffner, G.1, Ciborowski, J.3, Hamaed, A.1, Drouillard, K.1, Letcher, R.1, 2, 1 University of Windsor, Great Lakes Institute for Environmental Research, Windsor, Ontario, Canada2 Environment Canada, Canadian Wildlife Service, National Wildlife Research Centre, Ottawa, Ontario, Canada3 University of Windsor, Department of Biological Sciences, Windsor, Ontario, Canada
Lake Erie is the southernmost, shallowest, warmest, and most biologically productive of the five Great Lakes. High urban and industrial activities on its shores, and upstream on the Lake Huron-Detroit River-Lake Erie corridor, which means that Lake Erie is particularly vulnerable to contamination by organohalogen contaminants. Brominated flame retardants (BFRs) as contaminants in the Great Lakes ecosystem are of increasing concern. Polybrominated diphenyl ether (PBDE) congeners such as 2,2',4,4'-tetrabromoDE (BDE47) and 2,2',4,4',5-pentabromoDE (BDE99) are important environmental BFRs. The congener 2,2',3,3',4,4',5,5',6,6'-decabromoDE (BDE209) is of particular environmental concern, and is the primary component in a currently used PBDE flame retardant mixture known as decaBDE. Tetrabromobisphenol-A (4,4'-isopropylidenebis(2,6-dibromophenol)), commonly known as TBBPA, is also a major, commercially-used BFR. We presently report on the patterns, concentrations and distribution of nine major PBDE congeners, including BDE209, and TBBPA in surface sediment samples from sites spanning Lake Erie, and collected during May to June, 2004. Across Lake Erie, BDE209, BDE47 and BDE99 were the dominant congeners in sediment, where BDE47 and BDE99 comprised >70 % of the sum concentration (8PBDE) of eight major PBDE congeners (BDE28, 47, 100, 99, 154, 153, 138, and 183). 8PBDE concentrations varied in sediment samples from sites across Lake Erie. The 8PBDE concentrations were generally low (0.25 - 0.5 ng/g dry weight) in the eastern and central basins. The 8PBDE concentration in the western basin was 0.5 - > 5.0 ng/g d.w., and the highest concentration was 11.7 ng/g d.w. at a site near the western-central side of Point Pelee. Higher 8PBDE concentrations were generally found at near shoreline sites in the western basin. In contrast to the PBDEs, TBBPA was only quantifiable at two sites, one at the mouth of the Detroit River (0.51 ng/g d.w.), and at detection levels in the mid-eastern basin. Our results indicate that PBDE contamination and deposition to sediment is highest in the western basin, and PBDEs are a more significant sediment contaminant than TBBPA, which is likely a function of water-sediment partition coefficients.
WP217 (BIB-1117-816704) Application of an Exotic Mineral Tracer to Determine the Depth Surficial Sediment Mixing Layer and Document Sediment Chronology.
Start time: 8:00 AM
Biberhofer, J1, 1 National Water Research Institute, Environment Canada, Burlington, Ontario, Canada
The depth to which surface sediment mixes is an important variable in assessing remediation alternatives for contaminated sediment deposits. This dynamic layer below the sediment-water interface is an integration of both biotic activity such as bioturbation and abiotic physical processes. Entrainment of a tracer applied to the surface of sediment has been used as an indicator to measure the depth of the active mixing layer. The tracer was enriched in elements that were exotic to or present at low background concentrations in the area of study. Initial surface concentrations were measured 24 hours after application. Core samples were collected 1 year post application and sectioned at 1 cm intervals to determine the depth of the tracer entrainment during the one year period. Application of the conservative tracer can also be used to insert an artificial horizon into the sediment chronology. Results will be presented for sites located in river and riverine-lake environments where the same tracer compounds were applied. The sites were resampled 6 years post-application with dive-collected sediment cores. The tracer horizon was measurable and its depth in the sediment profile varied in relation to the physical environment.
WP218 (REV-1117-817180) The use of sediment-profile imaging for contaminated sediment assessment: Pacific Northwest harbor and river examples.
Start time: 8:00 AM
Revelas, E.1, Browning, D.2, 1 Integral Consulting, Inc, Olympia, Wa, USA2 Browning Environmental Services, Olympia, WA, USA
Sediment-profile imaging (SPI) provides in-situ information on animal-sediment interactions, stratigraphic properties, geochemical processes, and physical dynamics at the sediment-water interface (0-20 cm depth). Two examples of SPI supporting the interpretation of sediment quality, benthic conditions, and fate and transport at complex contaminated sediment sites are detailed here. The sediment triad approach (sediment chemistry, toxicity, and infaunal community characterization) was used to characterize the Hylebos Waterway CERCLA site (Commencement Bay, Tacoma, WA). SPI data were also collected to provide in-situ information on sediment disturbance patterns in the waterway, which were then related to the triad data. The SPI data provided insights on the natural and anthropogenic processes that confounded interpretation of the triad data. SPI showed that toxicological and benthic infaunal community responses in the waterway were affected by wood product operations, organic loading, and anthropogenic physical disturbances. Two additional waterway characterization benefits provided by SPI were: 1) high resolution disturbance gradient mapping that was used to focus more expensive chemical and toxicological testing, and 2) determining that several adverse benthic responses were due to vessel traffic and accumulations of wood debris from sort/transfer operations rather than contamination. A SPI survey of the Portland Harbor/Lower Willamette River (Oregon) CERCLA site, was conducted as an early step in the remedial investigation of this large, complex, riverine sediment site. SPI was used to define benthic regimes, i.e., broad areas that shared attributes such as sediment texture and depositional/erosional features, geochemical characteristics such as sedimentary methane abundance, and functional infaunal types. The SPI information was used to help: 1) define an ecologically-relevant surface sampling (i.e. mixed layer) depth for the RI and risk assessments; 2) develop a working physical conceptual site model; and 3) optimize an extensive sediment chemical and biological nature and extent sampling program by focusing on regions exhibiting strong benthic gradients.
WP219 (ARE-1118-165593) Modeling the effects of water-washing and evaporation on petroleum hydrocarbon mixture composition using comprehensive two-dimensional gas chromatography.
Start time: 8:00 AM
Arey, Jeremy1, Nelson, Robert1, Xu, Li1, Reddy, Christopher1, 1 Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Phase transfer processes such as water-washing and evaporation may drastically affect the composition and persistence of residual oil and fuel contamination in the environment. However, changes in the complex chemical compositions of petroleum mixtures resulting from these processes have not been quantitatively deconvolved or methodically distinguished from other weathering effects. By relating comprehensive two-dimensional gas chromatography (GCxGC) retention data of petroleum mixture compounds to their phase partitioning properties, we studied the impacts of water-washing and evaporation on the detailed chemical compositions of residual petroleum mixtures found in contaminated sediments of Cape Cod, MA. GCxGC provides nearly complete composition data for some complex mixtures such as petroleum hydrocarbons. However, the potential wealth of physical property information contained in the corresponding two-dimensional chromatograms has remained largely untapped. We developed a simple but robust method to estimate GCxGC retention indices for diesel-range hydrocarbons. The resulting two-dimensional retention indices were used to estimate the liquid vapor pressures, aqueous solubilities, octanol-water partition coefficients, and vaporization enthalpies of a complete set of diesel fuel hydrocarbons. Partitioning properties were typically estimated within a factor of two; this is not as accurate as previous estimation or measurement methods. However, these relationships allowed powerful and incisive analysis of phase transfer processes affecting petroleum hydrocarbon mixtures in the environment. The effects of volatilization and water-washing on petroleum mixtures were separately modeled and distinguished from other environmentally important removal processes such as biodegradation and phototransformation. Consequently, the increased resolution and physical property estimates afforded by GCxGC could significantly advance our understanding of processes that act on petroleum hydrocarbons in the environment.
WP220 (DUH-1116-941504) Phytoextraction and Harvesting Efficiency of Wetland Plants for use as a Non-Intrusive Remedial Alternative.
Start time: 8:00 AM
Duh, D1, Murray, M1, Medeiros, W2, 1 Shaw Environmental, Inc., Edison, NJ, USA2 Brookhaven National Laboratory, Upton, NY, USA
Brookhaven National Laboratory (BNL) forms part of the upper drainage area or headwater of the Peconic River, a coastal plain stream in Long Island. Investigations have reported the presence of contaminants in the sediment of the Peconic River that likely originated from BNL's sewage treatment plant. Mercury and PCBs are of greatest concern, but other metals, pesticides, and radionuclides, particularly Cesium-137, are also of concern, and remediation of the sediment is warranted. The upper portion of the Peconic River is primarily an emergent wetland. It is dominated by cattails, common reed, and sedges. Concerns regarding the ecological impact of remediation using traditional sediment removal methods have led to the evaluation of less intrusive remediation techniques. One potential remedial technique that was investigated is the use of natural phytoextraction by the common plants already present coupled with harvesting of the above-ground portion of these plants. The study was conducted in two parts. First, samples of the above-ground portion of dominant plants and samples of sediment were collected and analyzed. Second, a model of the reduction of sediment contaminants via harvesting was developed. Based on the analysis and interpretation of the bioaccumulation data, phytoextraction and harvesting does not appear to be a viable solution for remediation at this particular site.
WP221 (KHI-1117-348147) Characterization and distribution of dioxin-like and estrogenic contaminants in sediment from Korean coasts.
Start time: 8:00 AM
Khim, JS1, Villeneuve, DL2, Kannan, K3, Johnson, BG3, 4, Giesy, JP5, 6, Koh, CH1, 1 Seoul National University, Seoul, Korea2 U.S. Environmental Protection Agency, Duluth, MN, USA3 State University of New York at Albany, Albany, NY, USA4 University of Cartagena, Cartagena, Colombia5 Michigan State University, East Lansing, MI, USA6 City University of Hong Kong, Kowloon, China
Sediments from inland areas and open bays along the Korean coast were analyzed to examine the distribution of dioxin-like and estrogenic compounds. Concentrations of target chemicals varied considerably among locations (Lake Shihwa, Masan Bay, and Kwangyang Bay), and between inland and coastal areas. Principal Component Analysis (PCA) of contaminants measured in sediments showed that all the inland locations from Lake Shihwa were highly contaminated and the variations among locations were explained predominantly by the distribution of alkylphenols and polycyclic aromatic hydrocarbons (PAHs). PCA of PAH congener profiles among locations indicated that automobile was a major source for PAHs contamination. Dioxin-like and estrogenic activities associated with sediment from inland sites were approximately 3- and 6-fold, respectively, greater than those associated with open bay locations. The target dioxin-like and estrogenic compounds measured in raw extracts of sediments accounted for approximately 20 and 40% of the activities measured in the sediment extracts. The results suggest that a combination of instrumental and bioanalytical measurement of dioxin-like and estrogenic compounds is a valuable approach to screen, identify, and prioritize risks posed by contaminants in complex environmental matrices.
WP222 (ROS-1117-710467) Risk assessment of contaminated river sediments linked with urban wet-weather discharges.
Start time: 8:00 AM
Rossi, L.1, Chèvre, N.1, 1 Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, Switzerland
During rain events, wash-off of impervious surfaces and combined sewer overflows contribute to potential risk in receiving waters. In fact, a lot of pollutants are adsorbed on particles during wet-weather discharges (heavy metals, PAHs, organic compounds...). For example, more than 80% of heavy metals are linked to TSS (total suspended solids). Depending on the flow conditions in the receiving waters, theses particles could settle on the riverbed and accumulate as contaminated sediments. It is therefore of particular importance to assess the risk of such discharges. This can be done by comparing the pollution due to wet-weather discharge with ecotoxicologically-based environmental quality criteria. In this study, we propose new quality criteria for sediments affected by urban wet-weather discharges. In order to calculate the risk, these criteria are compared with simulated particle deposition and resuspension at the riverbed. The simulation is conducted using a simplified probabilistic and stochastic approach. Depending on the flow conditions in the receiving water, erosion or depositions of particles are estimated for a fictitious square meter of riverbed. Processes such as armor effects (trapping of particles in the hyporrheic interstitial) are also considered. In order to assess the uncertainties in these processes, the different parameters of the models vary in given range for each run of a Monte-Carlo simulation. As a result, the model returns the probability of fulfilling the ecotoxicological criteria. This method allows us to pragmatically estimate the risk of sediment contamination due to wet-weather discharges and, subsequently, to plan adequate control measures.
WP223 (SHA-1118-278079) Remediation of Sediments: a Review of our Asian Projects.
Start time: 8:00 AM
Shaw, R1, Murphy, T2, Droppo, I2, Guo, J2, Leppard, G2, Chan, L3, Kumagai, M4, Irvine, K5, Sampson, M6, 1 Redlog Inc, Bangrak, Bangkok, Thailand2 Environment Canada, Burlington, ON, Canada3 China Harbour Engineering Co., Hong Kong4 State Lake Biwa Environmental Research Institute, Japan5 State University College at Buffalo, New York, USA6 Resource Development International, Cambodia
Sediments in Asia differ from most documented studies. For one, atmospheric pollution results in significant deposition of sulfur, dissolution of vivianite in lake sediments and in turn eutrophication. We demonstrated in Lake Biwa Japan, that iron treatment can control this reaction. In Hong Kong, former discharges of sewage into typhoon shelters resulted in extreme concentrations of sulfide in sediments and corrosive odors. Full-scale in situ injection of calcium nitrate into sediments resulted in complete oxidation of the sulfide, removal of odors, and return of fish, birds and people to the waterfront. In the Mekong River, we have determined that mercury has killed at least one dolphin. The sources are still being evaluated via sediment and other analyses. We have developed a procedure to inactive mercury in sediments in situ by reactive capping. In Kuwait, we conducted two pilot-scale sediment treatments and demonstrated that a highly weathered oil can be bioremediated. The high concentration of salts requires a special formulation to avoid further mineral precipitation.
WP224 (MCW-1117-564493) Characterization of Heterogeneous Sediment and the Development of a Prioritization Strategy for Remediation.
Start time: 8:00 AM
McWilliams, L.1, Fitzgerald, B.2, Santiago, R.3, Vieira, C.4, Mahoney, M.5, Spadaro, P.6, 1 Blasland, Bouck & Lee, Inc., Portland, Oregon2 Hamilton Port Authority, Hamilton, Ontario, Canada3 Environment Canada, Toronto, Ontario, Canada4 Ministry of the Environment, Ontario, Canada5 Blasland, Bouck & Lee, Inc., Boston, Massachusetts6 Blasland, Bouck & Lee, Inc., Seattle, Washington
Contaminated sediment in the vicinity of Randle Reef, Hamilton Harbour, Ontario, is distributed in a thin, uneven (0.25-3 m), chemically heterogeneous layer, over a large (>1 km wide) region with locally steep topography. Given this challenging geometry, the proposed remediation strategy involves: 1) construction of an engineered containment facility (ECF) to contain (and subsequently cap) the most highly contaminated sediment in-situ, and 2) dredging of the surrounding less contaminated sediment and placement into the ECF. To maximize use of the ECF volume, a strategy was developed to ensure that the most contaminated sediment is remediated first, followed by progressively less contaminated sediment. This was accomplished by dividing the site into sub-areas, each of which was assigned to one of four sediment priority categories. These priority categories were formulated to identify those areas where remediation would be the most effective in meeting the project objectives of 1) reduction of mass of chemicals of interest (COIs, including PAHs and selected metals) in site sediment and 2) removal/containment of site sediment with demonstrated toxicity. Contaminated sediment thickness was constrained using chemical and sediment core information. The volume for each sub-area was computed by integrating the total contaminated sediment volume within sub-area. A representative average concentration was calculated for each COI within the contaminated sediment layer in each sub-area. Finally, total contaminant mass was computed for each of the COIs, as well as the mass distribution for each COI amongst the prioritized sub-areas. This analysis quantifies the COI mass that will be contained in place beneath the ECF, as well as the COI mass that will be remediated as the contaminated sediment in each successive sub-area is dredged. This tool will be used during dredge plan design to ensure that the greatest possible environmental benefit is achieved in the most cost effective manner.
WP225 (PAR-1117-830860) 23-acre multilayer sediment cap in dynamic riverine environment using organoclay as adsorptive capping material.
Start time: 8:00 AM
Parrett, K1, Blischke, H 1, 1 Oregon Department of Environmental Quality, Portland, Oregon, USA
The McCormick and Baxter Creosoting Company was founded in 1944 to produce treated wood products. The site is located along the Willamette River in Portland, Oregon. From 1945 to 1969, creosote-contaminated waste water and cooling water were discharged directly into the Willamette River. Creosote was identified in sediment at as much as 90 feet below the mudline and also found to be seeping into the river from upland source areas. The selected sediment remedy required capping areas that contain contaminant concentrations above human health and ecological risk-based protective levels, or that exhibit significant toxicity to biological organisms in the near surface. Surface water, groundwater, and transition zone water samples were collected in September 2002 and 2003 and crayfish tissue sampling was conducted in 2003. Results from these investigations and previous site investigation data were used to determine appropriate construction for the sediment cap as well as providing baseline conditions prior to cap installation. The sediment cap was installed during the summer of 2004. The footprint encompasses 23 acres and consists of 2 to 5 feet of sand with an average grade of 2.5 horizontal to 1 vertical. Approximately 131,000 tons of sand was placed over contaminated sediment and 600 tons of organoclay were placed over the creosote seep areas as an active capping material to prevent premature breakthrough of the creosote. Articulated concrete block armoring was placed over the shore and shallow water portions of the cap and rock was used as armoring over the remaining portion of the cap. The project was conducted collaboratively with EPA, NOAA, and local American Indian Tribes. Much of the work needed to be completed within a narrow Endangered Species Act -mandated fish in-water construction window. The design included considerations for enhancing fish habitat and protection.
WP226 (THO-1117-836405) Comparative evaluation of geostatistical methods for delineating PCB remediation areas and volumes, Lower Fox River.
Start time: 8:00 AM
Thornburg, T.1, Wolfe, J.2, Barabas, N.2, 1 Anchor Environmental, L.L.C., Portland, OR2 Limno-Tech, Inc., Ann Arbor, MI
The performance of three different interpolation methods and a range of statistical significance levels were evaluated for delineating sediment remediation areas and volumes for the remedial design of the Lower Fox River, Wisconsin. The three methods evaluated included Thiessen polygons, a hybrid of ordinary kriging and indicator kriging, and full indicator kriging. The kriging methods are generally preferred over Thiessen polygons because they provide valuable information about uncertainty and spatial correlation structure, and can be cross-validated. However, Thiessen polygons are useful for delineating sediments above 50 ppm PCBs which require special disposal; these areas constitute the upper 10 percent of the PCB data and kriging of these extreme values is difficult. For areas where dredging is the selected remedy, dredge prism designs at a range of significance levels (defined as the probability of exceeding the cleanup level at a given location) were evaluated using cross-validation metrics to inform risk management decisions. These decisions involve balancing the risk of leaving contaminated sediment behind (false negative error) versus the risk of unnecessarily dredging clean material (false positive error). Additional protection against false negative errors will be provided by post-dredge confirmation sampling. A significance level of 0.5 provided the optimum balance of sensitivity and specificity, the highest accuracy, and the least bias in the dredge cut depth. In practice, more sediment will be removed than the selected significance level would indicate because additional deepening of the dredge prism occurs during dredge plan design and to account for contractor overdredging allowance. The hybrid ordinary/indicator kriging method and the full indicator kriging method showed excellent agreement and very comparable performance metrics, confirming the robustness of the geostatistically-based sampling grid. However, full indicator kriging showed less attenuation of extreme values and is the preferred method for use in remedial design.
WP227 (SAV-1117-721585) Environmental contaminant levels in bottom sediments and biota from the Kola Bay, Barents Sea, Russia.
Start time: 8:00 AM
Savinova, T1, Dahle, S1, Alexeeva, L2, Chernik, G2, Samsonov, D2, Plotitsyna, N3, Zhilin, A3, Mokrotovarova, O4, Matishov, D5, Futsaeter, G6, 1 Akvaplan-niva, Polar Environmental Centre, Tromso, Norway2 SPA "Typhoon", Obninsk, Russia3 Knipovich Polar Research Institute on Fishery and Oceanography, Murmansk, Russia4 Murmansk Regional Department for Hydrometeorology and Environment Monitoring, Murmansk, Russia5 Murmansk Marine Biological Institute, Murmansk, Russia6 Norwegian State Pollution Control Authority, Oslo, Norway
The Joint Assessment and Monitoring Programme (JAMP) pilot study is a part of the bi-lateral project between Russia and Norway on harmonisation of monitoring of hazardous substances. The pilot study started in 2002, as a follow up a decision by the Joint Norwegian-Russian Environmental Commission to initiate co-operative activities on harmonisation to OSPAR standards. During 2002-2005 the surface sediment samples (0-2 cm) and biota (cod and blue mussels) were annually analysed for heavy metals, persistent organic pollutants (POPs), including both v established and new compounds, and polycyclicaromatic hydrocarbons (PAHs). Sampling and analyses were carried out according to JAMP guidelines. Grain size, total organic carbon and total nitrogen content were determined in the bottom sediments as well as all morphological and biological parameters of cod and mussels. Analyses were performed at Typhoon analytical laboratory (Obninsk, Russia); PINRO laboratory (Murmansk, Russia) and Unilab Analyse (Polar Environmental Centre, Tromso, Norway). The analytes were: trace elements (Zn, Cu, Cd, Ni, Pb and Hg), PAHs v 21 compounds; basic POPs v PCBs (50 ortho-substituted congeners), DDT-family (6 isomers), hexachlorobenzene (HCB), hexachlorocyclohexane (HCH, -,- and -isomers), chlordane compounds (heptachlor epoxide, oxychlordane, cis-and trans-chlordane, cis- and trans-nonachlor, heptachlor, endrin, dieldrin, mirex); new compounds – coplanar PCBs, polybrominated diphenyl ethers (PBDEs), and dioxins/furans (PCDD/PCDF). Levels of all contaminants analysed in bottom sediment samples from the Kola were similar to those in the Norwegian harbors and varied, according the Norwegian Pollution Control Authority (SFT) classification system from slightly contaminated to moderately contaminated. POP levels in biological samples did not exceed current Russian criteria for quality of seafood. PCDFs contributed more than 50% to the TEQ in the bottom sediments, while in biological samples, PCBs were a major contributor. In 2005 this study will be continued in the White and Pechora seas.
WP228 (PAR-1114-212604) Port Valdez Sediment Coring Project.
Start time: 8:00 AM
Parkin, T1, Trefry, J2, Savoie, M3, 1 Prince William Sound Regional Citizens' Advisory Council, Valdez, Alaska, USA2 Div of Marine & Environmental Systems - Florida Inst of Science, Melbourne, Florida, USA3 Kinnetic Labs, Anchorage, Alaska, USA
The ballast waste water treatment plant (BWT) at the Valdez Marine Terminal (VMT) has for many years been the source for hydrocarbon input into the water of Port Valdez, Alaska. Approximately 30 gallons of weathered Alaska North Slope (ANS) crude oil enter the Port everyday but in the past this has reached as high as 130 gallons a day. Prince William Sound Regional Citizens Advisory Council (PWSRCAC) is concerned over the long term impacts of this practice and a sediment coring program has been conducted to collect cores from within the port and from a reference bay. Cores were sub-sampled and chemical analysis was conducted to determine hydrocarbon content and their origin as a function of time and space within Port Valdez. Prior to the development of the VMT, oil in the region mostly came from California and sources of hydrocarbon input into the Port include spillages caused by the Great Alaskan Earthquake of 1964. Radio-isotope age-dating was conducted on the sediments to determine changes in hydrocarbon input into the port and also sedimentation rates in the region. The aim of the project was to detect the long term input of hydrocarbons into the port, identify input trends during the operation of the VMT and to identify the origin of the contamination. The project assessed the potential risk for re-introduction of buried hydrocarbons into the environment as the result of a seismic event causing seabed slumping and sediment down slope transportation. Preliminary results show that there is an accumulation of hydrocarbons around the vicinity of the VMT outfall with a chemical signature indicating the VMT as the probable source of these compounds. Sediment isotope dating shows a trend of hydrocarbon input into the Port related to the throughput of the Trans-Alaska Pipeline and further studies are planned to investigate this trend.
WP229 (KAS-1118-373585) Bioremediation Mechanistic Modeling for PAH-Contaminated Sediments from the Portland Harbor, Oregon.
Start time: 8:00 AM
KASSIM, Ph.D., T.1, 1 Seattle University, Department of Civil and Environmental Engineering, P.O. Box 222000, Seattle, WA 98122-1090, USA
Bioremediation is a clean-up technology that was initially presumed to have great potential, but it became evident that just like the physical and chemical treatment techniques for contaminated solid-phase environments, biological methods had their disadvantages. Long treatment periods and high residual concentrations were the main problems. This is true for polycyclic aromatic hydrocarbon (PAH)-contaminated sediments. Because of their hydrophobicity and low water solubilities, PAHs strongly interact with the sediment matrix and can even form separate phases. Microorganisms can only degrade dissolved PAHs, and so they have to be released from the solid-phase to an aqueous-phase in which they are available. As a result of low mass-transfer rates in the sediment matrix, this release is often limiting the effectiveness of bioremediation. The physical states in which PAHs are present in bottom sediments mainly determine the potential of remediation techniques. It must be analyzed whether the mobility requirements of possible remediation techniques can be met in and by the physical state of the contaminant in the sediment matrix. The aim of this paper is to translate the theoretical considerations concerning the mass-transfer of PAHs such as in different physical states in bottom sediment representing the Portland Harbor of Oregon to the situation where microorganisms can degrade these contaminants. The effect of several model parameters on the availability of PAHs towards microbial populations is illustrated. Mass-transfer and biodegradation models are also developed for various theoretical physical states of PAH-contaminated sediments. These mechanistic models are used to calculate the treatment periods necessary for complete removal of PAHs from the harbor sediment batch conditions. Results indicate that the PAH bioremediation in such systems is mainly mass-transfer limited. Therefore, the potential for bioremediation, as a treatment technique for PAH-contaminated sediments, is mainly determined by the mass-transfer dynamics of PAHs. Under mass-transfer limited conditions, simplified mathematical models, based on the assumption of a zero dissolved PAH concentrations, can be used to predict the period of time needed for complete bioremediation.
WP230 (HIN-1112-902578) A Streamlined Approach for Conducting a Screening-Level Ecological Risk Assessment of a Marine Harbor.
Start time: 8:00 AM
Hinckley, D1, Speicher, J4, Leather, J3, Emsbo-Mattingly, S2, Yeutter, L4, 1 EA Engineering, Science and Technology, Sparks, MD, USA4 Department of the Navy Engineering Field Activity Northeast, Philadelphia, PA, USA3 Department of the Navy SPAWAR System Center, San Diego, CA, USA2 Newfields Environmental Forensics Practice, Rockland, MA, USA
It is often difficult to obtain adequate coverage of a marine environment using standard sampling approaches. Potential releases to this type of environment may travel far from the point of release, and it is difficult to assign culpability due to multiple sources of contaminants such as polycyclic aromatic hydrocarbons (PAH). Rapid-sediment characterization (RSC) utilizing X ray fluorescence for metals and PAH immunoassays were performed in a confined marine harbor as well as three reference locations. Utilizing the results of RSC analyses a smaller number of these samples were designated for quantification by standard fixed-laboratory analysis. Correlations between RSC and fixed-laboratory results will be presented, as well as using these correlations to contour concentrations of contaminants in the harbor. A screening-level Ecological Risk Assessment was performed based on the quantified results, and will be discussed. In addition limited number of samples were designated for PAH environmental forensics characterization, results of which will be presented. RSC provided a cost-effective method for the selection of not only samples to be quantified, but further, samples to be forensically analyzed for source attribution.
WP231 (MOU-1117-832154) The significance of non-aqueous phases in assessing the toxicity of contaminated sediments.
Start time: 8:00 AM
Mount, D1, Heinis, L1, Highland, T1, Hockett, J1, Jenson, C1, Norberg-King, T1, 1 U.S. EPA/ORD, Duluth, MN, USA
Although oils, tars, and other non-aqueous liquids are common sources of contamination to aquatic sediments, the toxicity of such contamination has generally been attributed to component chemicals, particularly PAHs. While PAHs can be toxic to aquatic organisms, it is not entirely clear that they are the only source of toxicity from contamination by non-aqueous phases. In laboratory experiments, reference sediments were spiked with either purified triolein or mineral oil, and tested for toxicity. Toxicity to both Hyalella azteca and Chironomus dilutus was observed, even though these two model oils are not thought to have compenents with sufficient solubility to cause toxicity. Additional experiments using a water accommodated fraction (WAF) of mineral oil showed no toxicity to either species, suggesting that the effects observed in spiked sediment are not mediated via soluble components of the oil, but perhaps by the presence of the non-aqueous phase itself. When "oil" was quantified gravimetrically via solvent extraction, the exposure response curves for both model oils were similar. Measurements of solvent-extractable material in toxic field sediments indicate the presence of non-aqueous phases at concentrations comparable to those found toxic in spiked sediment tests. The results of these studies suggest that greater attention should be given to the quantification and assessment of effects from non-aqueous phases in field sediments. This abstract does not necessarily reflect EPA policy.
WP232 (HUN-1117-734484) Models and Measurements in Assessing Contaminant Accumulation in Bottom Sediments.
Start time: 8:00 AM
Hunt, J1, Johnson, B1, Esser, B2, 1 University of California, Berkeley, CA, USA2 Lawrence Livermore National Laboratory, Livermore, CA, USA
Many persistent chemicals of concern are associated with fine particles, and particle transport processes determine contaminant accumulation in bottom sediments. While predictive modeling is an essential tool in understanding future risks and the efficiency of sediment remedial approaches, considerable insight can be gained from an analysis of sediment profiles. A mechanistic understanding of particle transport processes would have to address particle aggregation and disaggregation in the water column coupled with salinity and fluid mixing processes, aggregate dynamics within the benthic boundary layer, sediment consolidation, chemical and biological diagenesis, and exchange processes with the overlying water column. An alternative to completely predictive modeling is an approach based on the analysis of tracer and contaminant profiles within sediments to assess historical inputs, and from that predict future conditions of sediment accumulation rates and mixing processes. Data on the sediment record has been constrained by the limited depth resolution and spatial coverage for radioisotopic tracers and contaminants. The Seaplane Lagoon at the former Alameda Naval Air Station on the shores of San Francisco Bay demonstrates the tradeoffs in models and measurements for assessing historical sediment contamination. Sediment accumulation rates from 20 sediment cores over the 50 ha lagoon are obtained from radioisotopic profiles. Excess Radium-226 was measured within all 20 cores and these data identify the source and discharge history. Metal profiles were obtained in several sediment cores at greater than 1 cm depth resolution using x-ray fluorescence of frozen sediment cores at the LBNL Advanced Light Source. The combination of a detailed sediment chronology, excess Ra-226 and metal profiling, and statistical interpolation permits estimation of the inventory of sediment contamination and the historical reconstruction of contaminated surface sediments. Predictive particle and sediment transport models do not provide the same level of resolution and certainty at this site.
WP234 (REI-1117-511605) Sediment and contaminant release during gas ebullition.
Start time: 8:00 AM
Yuan, Q1, Valsaraj, K1, Willson, C1, Reible, D2, 1 Louisiana State University, Baton Rouge, LA, USA2 University of Texas, Austin, TX, 78712
Significant quantities of gas are generated by labile organic materials in sediments. The implications for the gas generation and subsequent release for contaminants from sediments are unknown but may include enhanced direct transport as well as physical disruption of the sediment increasing other modes of transport such as porewater advection and diffusion. The behavior of gas in sediments and the resulting migration of a PAH, phenanthrene, was investigated in an experimental system with methane injection at the base of a sediment column. Hexane above an overlying water layer was used to trap any phenanthrene migrating out of the sediment layer. The rate of resuspension of solid particulate matter from the sediment bed into the overlying water layer was also monitored. The experiments indicated that significant amounts of both solid particulate matter and contaminant can be released from a sediment bed by gas movement with the amount of release related to the volume of gas released. A thin sand capping layer was found to dramatically reduce the amount of contaminant released with the gas, presumably due to the reduced resuspension potential of sand relative to fine-grained contaminants and the lack of significant contamination of the sand. The experimental data was used to predict the contaminant migration potential of gas ebullition under a variety of field conditions and draw conclusions about the implications of this mechanism for contaminant release under natural conditions.
WP235 (CHA-1117-059072) Modeling the impact of flocculation on the fate of PCBs in mesocosms.
Start time: 8:00 AM
Chang, Chihwei1, Schneider, Abby1, Baker, Joel1, 1 University of Maryland, Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, Maryland, USA
Resuspended sediment forms flocs that have higher organic carbon, porosity, water content, and surface area than the original sediment particles. Recent research has noted the importance of flocculation in the fate of polychlorinated biphenyls (PCBs), specifically that flocs will affect the fate of PCBs by changing the measured partition coefficient, organic carbon content, sorption rates, and therefore water column residence times. In this study, a PCB model that includes flocculation has been developed. This coagulation model simulates the flocculation for both organic carbon and inorganic solids ranging in diameter from 2.5 to 350 m. It also tracks the temporal variation of organic carbon content, density, stickiness coefficient, porosity, and partition coefficient for each size class of particles. The model was calibrated using the Shear Turublence Resuspension Mesocosms (STORM) tank experiments that mimic resuspension and settling of contaminated Hudson River sediment with realistic bottom shear stress. The objective of this model is to compare the residence time and steady state PCBs concentrations with traditional PCB models that do not include flocculation. The water column residence time of particles decreases with a larger initial particle size distribution, lower porosity, and higher fractal factor, stickiness coefficient, and organic carbon content. The PCB residence time depends on both the particle residence time and the partitioning behavior.
WP236 (DOB-1117-733445) Identifying suitable reference bayous for impacted sites along the Houston Ship Channel.
Start time: 8:00 AM
Dobberstine, J1, Howard, C1, Horne, J2, 1 School of Science and Computer Engineering, the University of Houston Clear Lake, Houston, Texas, USA2 PBS&J Environmental Toxicology Laboratory, Houston, Texas, USA
Recent studies indicate that anthropogenic contaminants in the Galveston Bay estuary have resulted in numerous negative effects to water and sediment quality, species diversity, and biologic productivity. The Houston Ship Channel (HSC) is widely considered the location of maximal concentrations for heavy metals and many commonly measured organic compounds in runoff, inflows, and waste discharges to the estuary. Significant differences in pollutant inputs and removal processes can exist within local sub-areas of the Galveston Bay estuary, making it difficult to compare sites across a large region. Determining appropriate reference sites for impacted tidal tributaries of the HSC has been a cause of concern regarding accurate assessment of their status. This research applied the sediment quality triad (SQT) approach toward assessing potential reference sites within the Galveston Bay system. Over three seasons, 15 stations were sampled among five potentially unimpacted bayous in the Galveston Bay system. For each station, the benthic macroinvertebrate community, sediment heavy metal concentrations, and organic contaminants including PAHs, organochlorine and organophosphate pesticides were determined. Whole sediment toxicity was evaluated through bioassays using Leptocheirus plumulosus and Mysidopsis bahia. Benthic macroinvertebrate, sediment, and water quality parameters from the bayou stations were compared to existing data from TMDL study sites within the HSC using the Engel and Summers Benthic Index and other statistical methods. Results comparing the benthic community, sediment composition, and sediment toxicity data indicate that determining suitable reference sites within the Galveston Bay system can be accomplished, but impacted estuarine sites must be matched to reference sites according to local variations in environmental qualities, including sediment consistency and salinity gradients. Based on the study parameters, two sites of the five bayou sites investigated show potential as reference sites for impacted sites along the HSC. This study has helped resolve a longstanding issue for impact assessments within the HSC.
WP237 (MCL-1117-823244) What activated carbon amendment teaches us about PCB bioavailability.
Start time: 8:00 AM
McLeod, P1, Luoma, S2, Luthy, R, 1 Stanford University, Stanford, CA, USA2 United States Geological Survey, Menlo Park, CA, USA
Predicting PCB bioavailability from contaminated sediments remains a top challenge for scientists and engineers. Such predictive capability would be very useful in assessing biological risk at a given site and modeling the potential outcomes of sediment remediation, including activated carbon amendment. In this work, we combine knowledge of sediment geochemistry and species-specific biology to help us achieve a better understanding of PCB bioavailability for two clam species (brackish-water, deposit-feeding Macoma balthica and freshwater, filter-feeding Corbicula fluminea) from three different sediments (Hunters Point, CA; Grasse River, NY; and Lake Hartwell, SC). Our 28-day laboratory bioaccumulation tests performed with Macoma and Corbicula show that activated carbon amendment can reduce PCB uptake in these sediment-dwelling organisms by up to one order of magnitude or more. However, the observed PCB bioaccumulation differs significantly between clam species and among sediment from different sites. Our results suggest that sediment-PCB binding characteristics, the transfer of PCBs from sediment to activated carbon, PCB homolog distributions, and organism feeding traits all influence PCB bioavailability for sediment treated with activated carbon. A biodynamic model which integrates these factors is assessed for its ability to quantitatively predict the clam tissue PCB concentrations observed in our experiments. The model expresses PCB uptake by organisms as a function of uptake from sediment, uptake from water, and contaminant elimination. Our results suggest that a biodynamic model is a useful tool for understanding the dynamics of PCB transfer from sediment to benthic organisms.
WP238 (SCH-1117-836840) PCB Partitioning to Flocculated Hudson River Sediment: Recharge of the Labile Pool.
Start time: 8:00 AM
Schneider, A1, Porter, E1, Baker, J1, 1 University of Maryland Chesapeake Biological Laboratory, Solomons, MD, USA
Numerous studies demonstrate that PCB desorption from sediment and soil is a two-stage process; the first ('labile') is rapid and reversible and the second ('resistant) is slow and irreversible. After a resuspension event it is unclear whether the labile pool is replenished from the resistant pool as sediments sit unmixed on the river bottom. In this study, both the desorption rates of individual PCB congeners from Hudson River sediment as well as their apparent partitioning coefficient were measured by repeatedly resuspending field-collected sediments into clean water in large mesocosms. Dissolved PCBs were measured using solid phase microextraction (SPME) to minimize the impact of colloids. Steady state PCB partitioning was reached by the start of the second day of each resuspension event and occurred on the same time scale as floc formation. When the sediment was initially resuspended there was a large release of PCBs into the dissolved phase. After just two hours of resuspension 25% of the total PCBs in the water column were in the dissolved phase. When the same sediment was resuspended for a third time only 15% of PCBs were in the dissolved phase. In the mesocosm with only one day of quiescence between resuspension events, the partition coefficient of the lower molecular weight congeners increased 35 to 65% from the first to the third resuspension event. When the quiescent time was increased to four days, the partition coefficient increased by only 15 to 20%. It appears that chronic resuspension resulted in less PCB release per event due to the slow recharge of the labile pool. For the low molecular weight congeners the labile pool recharged after approximately four days of quiescence. For the higher molecular weight congers the recharge rate is slower and four days of quiescence was insufficient to replenish the labile pool.
WP239 (GAR-1117-834891) A Model of TSS and PCB Flux in the Housatonic River.
Start time: 8:00 AM
Garland, E1, Mathew, R1, DiNitto, R2, Svirsky, S3, 1 HydroQual, Inc., Mahwah, NJ, USA2 Sleeman Hanley & DiNitto, Inc., Boston, MA, USA3 U.S. Environmental Protection Agency, Boston, MA, USA
Contaminant transport in aquatic systems is typically a function of hydrologic conditions. To improve the understanding of TSS and PCB mass fluxes in the Housatonic River, and in support of the development of a deterministic fate and transport model of PCBs, a flux analysis is performed. The calculations are based on intermittent measurements of water column TSS and PCB concentrations paired with river flow rates. Equations describing TSS and PCB mass fluxes are developed at the upstream and downstream boundaries, and an intermediate location within the primary study area (PSA). The TSS and PCB flux at each location are calculated as a function of flow-rate and the derivative of the flow-rate with respect to time in order to describe the hysteresis in concentrations observed between rising and falling limbs of the hydrograph. Further, the equations are applied to a long-term hydrograph, to develop estimates of the long-term average TSS and PCB mass fluxes. The results are then used to describe the net deposition or release of TSS and PCBs over large reaches of the river and to understand how the net source or sink changes as a function of river flow conditions. There is a net loss of solids within the PSA, with about 75% of the upstream load deposited within the PSA. The majority of the deposition occurs in the downstream half of the PSA. However, the system acts as a net source of PCBs. The upstream half of the PSA contributes to the PCB load entering the PSA and even though there is a decrease in the PCB load in the downstream half of the PSA, the net result is a 50% increase in the PCB load leaving the PSA. Both TSS and PCB flux into and out of the study area are dominated by high-flow events, with the flux during low-periods accounting for only about 10-30% of the total flux.
WP240 (SHA-1117-810653) Comparison of Adsorbents that can be used in In-situ Capping of Contaminated Sediments for PAH and PCB Sequestration.
Start time: 8:00 AM
Gardner, K, Sharma, B,
The aim of this work was to compare two types of adsorbents, activated carbon and organoclay, in removing Poly Aromatic Hydrocarbons (PAH) and Polychlorinated Biphenyls (PCB) from water to act as an active sediment cap. A maximum loading rate (mg of PAH/PCB added per gram of the sorbent) was also to be determined in this experimentation. The PAH used in this experiment was naphthalene, and the PCB congener was 2-chlorobiphenyl. Both of these provided a conservative case, as they are the most soluble and least sorptive of the PAHs and PCB congeners, respectively. Four different types of sorbents, three organoclay formulations and one activated carbon, were analyzed for their efficiency in removing PAHs and PCBs by measuring adsorption isotherms. Column studies are also being conducted, and the results of the two will be compared in this presentation.