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1998 Progress Report: Validation of Sediment Quality Criteria in Southeastern Estuaries
EPA Grant Number: R826201Title: Validation of Sediment Quality Criteria in Southeastern Estuaries
Investigators: Ringwood, Amy Huffman
Institution: South Carolina Department of Natural Resources , Marine Resources Research Institute
EPA Project Officer: Turner, Vivian
Project Period: December 1, 1997 through November 30, 2000 (Extended to November 30, 2001)
Project Period Covered by this Report: December 1, 1997 through November 30, 1998
Project Amount: $449,794
RFA: Contaminated Sediments (1997)
Research Category: Hazardous Waste/Remediation
Description:
Objective:The overall purpose of these studies is to evaluate the relationships between sediment/porewater parameters and biological responses (benthic community integrity, toxicity and bioaccumulation studies with infaunal and epifaunal bivalves) for metal contaminated sediments. The data will be used to evaluate the value of current bioavailability models to predict bioavailability and toxicity of metals to bivalve molluscs, and effects on benthic community integrity. Winter and summer studies are being conducted in order to assess the potential significance of seasonal changes. Progress Summary:
Summary of Activities
Studies were conducted at 10 sites in the Charleston Harbor area during winter (February, 1998) and summer (July, 1998) seasons. At each site, sediments were collected for sediment chemistry parameters, laboratory toxicity assays, and benthic community analyses. Juvenile clams (Mercenaria mercenaria) were deployed in situ for 7 day toxicity assays (based on growth), and clams and oysters (Crassostrea virginica) were deployed at each site for 30 day bioaccumulation studies. Datasondes were deployed in situ concurrently with the 7 day clam toxicity assays and continuous measurements of water chemistry parameters were recorded. Laboratory metal exposures to determine metal-specific EC50s for the IWTU estimates were also initiated.
Accomplishments
All field sampling activities and laboratory toxicity assays were completed as planned. The oysters and clams deployed for the extended period (i.e. 30 days) were lost (presumably vandalized) from one site (i.e. KOP) during the summer and one site during the winter (i.e. LTH). The AVS and SEM analyses were completed, and all Datasonde data were summarized. The remaining sediment (i.e. total metals and some PAHs) and tissue (metal concentrations) analyses are in progress. Summaries of some of the results to date for the various activities are provided.
Laboratory and in-situ 7-day clam toxicity assays were conducted successfully for all sites. The sites were classified a priori as reference (LTH, FOS, RAT, PAR) or degraded (DIE, KOP, NAV, NMK, NOI, SPY) based on existing sediment contaminant data. The sites were also classified as low or high salinity regimes. During the winter, growth rates were generally higher in the laboratory assays than the in situ studies. Lower growth rates of clams deployed in situ were probably related to lowered temperature and/or seasonal reductions in food abundance. No significant effects on growth were observed for the highly contaminated sites using the laboratory assays, but reduced growth rates were observed at 5 of the 6 contaminated sites with the in situ study. With the laboratory assays, 2 of the reference sites had significantly lower growth rates. Therefore laboratory assays may be characterized as having a 50% false positive rate (i.e. toxicity observed when not expected) and an 83% false negative rate (i.e. toxicity not observed when expected), whereas the false positive rate was 25% and the false negative rate was 20% for the in situ studies. During the summer, growth rates tended to be higher in situ than in the laboratory. No significant effects were observed for the highly contaminated sites using the laboratory assays, but significant reductions in growth were observed at 4 of the 6 contaminated sties with the in situ studies. Generally, the growth rates observed during in situ deployments were more consistent with expectations based on contaminant loading, and the false negatives and false positives were virtually eliminated.
Acid volatile sulfide concentrations (AVS) were generally higher in sediments collected during the summer than during the winter. However, intra-site variability was frequently high even though the sediment samples were collected in close proximity. The ratios of simultaneously extracted metals (SEM) to AVS concentrations were determined for both winter and summer samples. Based on the summed molar concentrations of Cd, Cu, Pb, Ni, Zn, there were no cases in which SEM/AVS > 1 at the contaminated sites. On the basis of the AVS model, no toxicity due to divalent metals would be expected at any of the sites.
Benthic community analyses (enumeration and taxonomy of 3 samples per site) were completed for winter and summer seasons. The average number of species found at the reference (LTH, FOS, RAT, PAR) vs contaminated (DIE, KOP, NAV, NMK, NOI, SPY) sites were 12 and 10, respectively. The average total abundance found at the reference (LTH, FOS, RAT, PAR) vs contaminated (DIE, KOP, NAV, NMK, NOI, SPY) sites were 81 and 111, respectively.
Laboratory experiments with clams for water only metal exposures were initiated. Based on the runs to date, the metal concentrations that reduced growth rates by 50% after 7 days (i.e growth EC50s) in ug/L were: Cu - 18.3; Pb - 636; Zn - 317; Ni - 911. From previous studies based on > 6 runs, the Cd EC50s was estimated as 100 ug/L.
Future Activities:During year 2, the following activities are planned: complete analyses of sediment and tissues samples; repeat field and laboratory studies during winter and summer seasons; conduct preliminary data analyses and evaluation of bioavailability models. Journal Articles:
No journal articles submitted with this report: View all 20 publications for this project
Supplemental Keywords:Ecosystem Protection/Environmental Exposure & Risk, Water, Geographic Area, Scientific Discipline, Waste, RFA, Ecosystem/Assessment/Indicators, Southeast, Ecological Risk Assessment, Ecological Indicators, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Ecosystem Protection, Contaminated Sediments, Ecology and Ecosystems, Geochemistry, bioavailability, risk assessment, water quality, marine ecosytems, sediment quality criteria, ecology assessment models, validation, pysicochemical parameters, sediment quality survey, contaminated sediment, Southeastern Estuaries, validation of models, metal contamination, ecological exposure, benthic biota, sediment porewater parameters, Ammonia, estuaries
Progress and Final Reports:
Original Abstract
1999 Progress Report
2001 Progress Report
Final Report