An Integrated Field and Laboratory Study of the Bioavailability of Metal Contaminants in Sediments
ER-1494
Objective
Quantifying metal-sediment phase associations using a sequential leaching scheme.
Sediments have commonly been thought of as the final repositories of contaminants in marine systems, particularly of particle-reactive metals. In recent years, however, it has been recognized that some metals may be mobilized by benthic animals and bioaccumulated. These animals can acquire metals dissolved in pore waters or overlying water and also can assimilate metals associated with ingested sediments. Recent data suggest that metal bioaccumulation is related to the geochemical phases with which the metals are associated in the sediments and to the particular biological characteristics of the species in question. To date, no systematic assessment across different types of sediments, metals, and benthic animals has been made.
The objective of this project is to evaluate the bioavailability of four metals of environmental concern from sediments with divergent characteristics and relate this information to the phase speciation of these metals in the sediments. Through an understanding of the geochemical and biological processes governing uptake, models can be established to make site-specific predictions of how metals will bioaccumulate from different sediment regimes.
Technical Approach
Using a specially designed and well-characterized leaching scheme, the geochemical work will establish the phase speciation of arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb) in oxic and anoxic estuarine sediments so that their mobility and bioavailability can be placed in a mechanistic/process context required for predictive capabilities. Data will reveal the diagenetic reactions that immobilize or release these metals. Moreover, the geochemical work will provide an important link to the bioavailability research by allowing the proper sediment phase speciation (e.g., iron oxides, carbonate, organic) to be used in the laboratory experiments and by providing data for testing biotic uptake models. The bioavailability research will quantify the transfer of As, Cd, Cr, and Pb from contaminated sediments to diverse suspension-feeding and deposit-feeding benthic animals that are abundant in coastal waters. Radiolabeled metals will be used to trace the rates and mechanisms of metal transfer from the various sediment phases into several bivalves and polychaetes. Based on the laboratory and field results, a bioenergetic-based kinetic model will be developed and tested to quantify sedimentary metal uptake by the study organisms. These data also can be used to provide quantitative predictions of metal concentrations in diverse species, including those used in biomonitoring programs.
Benefits
Concern over elevated metal concentrations stems primarily from the risks these contaminants can pose for living organisms (including man via contaminated seafood). Since organisms must first accumulate metals before any toxic effect can be manifested, it is necessary to assess the extent to which the metals bound to sediments are accumulated in benthic animals. This study will cover a range of sediments and benthic species and will provide a mechanistic explanation and quantitative evaluation of the rates and routes of metal bioaccumulation. The relationships between sediment phase association and metal bioavailability revealed may lead to more effective remediation strategies. It is also possible that new bioindicator organisms will be identified as more direct sentinels of sediment contamination. (Anticipated Project Completion - 2011)
Points of Contact
Principal Investigator
Dr. Nicholas Fisher
Stony Brook University
Phone: 631-632-8649
Fax: 631-632-3072
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.