Grantee Research Project Results
1999 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: Aja, Hayley
Project Period: December 1, 1997 through November 30, 2000 (Extended to November 30, 2001)
Project Period Covered by this Report: December 1, 1998 through November 30, 1999
Project Amount: $449,794
RFA: Contaminated Sediments (1997) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Hazardous Waste/Remediation , Land and Waste Management
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 the effects on benthic community integrity. Winter and summer studies are being conducted to assess the potential significance of seasonal changes.Progress Summary:
Studies were conducted at 10 sites in the Charleston Harbor area during winter (February 1998) and summer (July 1998) seasons. These studies were repeated at 10 sites during 1999; 5 were new sites and 5 were repeat sites, also sampled during 1998. At each site, sediments were collected for sediment chemistry parameters, laboratory toxicity assays (with juvenile clams, Mercenaria mercenaria), and benthic community analyses. Juvenile clams were also 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 conducted.Accomplishments. The field sampling activities and laboratory toxicity assays were completed as planned, with only a few minor problems. Over the 2 years of sampling, only two of the 30-day deployment systems (containing oysters and clams) were lost during 1998, and one was lost during 1999. High mortalities were observed with clams deployed in situ for 30 days during the summer. All water chemistry data have been summarized. All sediment chemistry analyses have been completed for the 1998 studies, and the data are currently in the final QA/QC evaluation stage; the final analyses for the 1999 studies are in progress. Summaries of some of the results (mostly from the 1998 season) are provided as examples of some of the data and findings emerging from these studies.
As reported previously from the 1998 studies, the 7-day clam juvenile growth rates observed during in situ deployments were more consistent with expectations based on contaminant loading than the laboratory assays. The 1999 studies revealed similar trends. However, after 2 years of analyses, it also is clear that there are caveats to both laboratory and field assays. Laboratory assays conducted under constant conditions frequently may not adequately reflect the realized effects of contaminants in natural systems, particularly those that undergo periodic fluctuations in dissolved oxygen, pH, etc. On the other hand, interpretation of in situ studies may be confounded by natural variables. We now have a substantial enough database of reference sites that we have started developing reference curves with confidence limits to aid in the identification of natural stressor effects. Another important finding associated with this has been the identification of pH as an important variable. Although pH is frequently regarded as a nonissue in marine systems, we are observing profound effects on clam growth when average bottom water pHs drop below 7.4 (based on 5?7 days of continuous measurements with a Datasonde).
Acid volatile sulfide concentrations (AVS) were generally higher (significantly so in some cases) in sediments collected during the summer than during the winter. Although there is a trend of slightly lower SEM concentrations during the summer, there were no significant seasonal differences. The ratios of simultaneously extracted metals (SEMs) to AVS concentrations were determined for both winter and summer samples. Based on the summed molar concentrations of Cd, Cu, Pb, Ni, and Zn, there were no cases in which SEM/AVS > 1 at the contaminated sites. On the basis of the AVS model, little or no bioaccumulation of, or toxicity from, divalent metals would be expected at any of the sites. However, significantly higher metal concentrations were frequently observed in oysters deployed at contaminated sites. This trend occurred less often with clams. Despite the fact that clams live more intimately associated with the sediments, oysters tend to have much higher bioaccumulation rates. These species-specific differences were observed in similar studies conducted as part of the Carolinian Province EMAP program in 1994. Adverse effects on growth of oysters deployed in situ for 30 days were observed more frequently at degraded sites, and significant correlations between tissue metal concentrations and growth were frequently observed, particularly with the winter data when AVS levels tended to be lower (e.g., for regression of oyster tissue Cu versus oyster growth, the r2 was 0.91).
Benthic community analyses (enumeration and taxonomy of three samples per site) were completed for winter and summer seasons. Benthic assemblages collected at the 10 sites sampled in 1998 were dominated by polychaetes and oligochaetes . These two taxonomic groups comprised more than 60?85 percent of all fauna collected during both the summer and winter. To evaluate the overall condition of the benthic communities sampled at each site, we employed a new Benthic Index of Biological Integrity (B-IBI) that has been developed for use in southeastern estuaries (Van Dolah et. al., 1999). Overall, many of the contaminated sites had degraded or marginal B-IBI scores, but the scores were lower than anticipated at some of the less contaminated sites. These data have also been evaluated extensively with regard to the bivalve growth data and other biological parameters.
Future Activities:
During Year 3, the following activities are planned: complete analyses of sediment and tissues samples from the 1999 studies; repeat field and laboratory studies during winter and summer seasons more intensively at a fewer number of sites; generate numerous publications; and critically evaluate the bioavailability models.Journal Articles:
No journal articles submitted with this report: View all 20 publications for this projectSupplemental Keywords:
marine, estuary, ecological effects, environmental chemistry, southeast, Atlantic coast, South Carolina (SC), EPA Region IV., RFA, Scientific Discipline, Waste, Water, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Contaminated Sediments, Environmental Chemistry, Geochemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Ecological Effects - Environmental Exposure & Risk, Southeast, Ecological Risk Assessment, Ecology and Ecosystems, Ecological Indicators, ecological exposure, risk assessment, estuaries, validation of models, sediment porewater parameters, Southeastern Estuaries, benthic biota, bioavailability, contaminated sediment, Ammonia, sediment, sediment quality survey, sediment quality criteria, water quality, ecology assessment models, metal contamination, marine ecosytems, pysicochemical parametersProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.