Superfund Research Program
Application of Wildlife Biomarker Technologies in Remediation Decision-Making
Wildlife inhabiting chemically contaminated environments can serve as front line indicators of pollutant levels and potential health impacts. Wildlife biomonitoring at Superfund sites provides valuable data to support the design of remediation plans. These data can result in substantial savings of limited remediation resources while maximizing preservation of important natural areas and supporting effective remediation of the site. SBRP-funded researchers have developed biochemical, physiological, histopathological, and behavioral biomarkers in birds and mammals inhabiting contaminated sites to indicate chemical exposure and chemical effects.
As the science of biomarker technology evolves, researchers are finding additional and valuable applications. Researchers at Texas Tech University, a part of the University of Washington Superfund Basic Research Program, are applying biomarker methods developed in SBRP-funded projects to develop health-based exposure and effects data for wildlife. At a Superfund site in Alabama, contaminated with a mixture of DDT/DDE and mercury, they conducted field studies to test the hypothesis that certain biomarker levels are a function of contaminant concentrations. If true, this would allow remediation professionals to predict levels of contaminant residues and effects in resident wildlife populations based on concentrations measured in soil and diet samples.
The scientists conducted their research in a hardwood bottomland floodplain (a seasonal swamp) that is on the National Priority List. The site owners had conducted extensive soil analyses and the SBRP researchers incorporated these data into a geographic information system (GIS) to develop a geographic distribution of DDT, DDT metabolites and mercury soil contamination. The scientists placed approximately 200 nest boxes throughout the study site. Birds, as indicator species in waste site assessments, can yield significant information on trophic (food chain) transport and toxicity of contaminants for use in remediation decision-making. Cavity nesting species occupy a variety of trophic positions and habitats, and allow direct monitoring of adults and developing young. The SBRP researchers studied prothonatory warblers (Protonotaria citrea), using radiotelemetry to triangulate specific foraging positions and ranges for both male and female adults. The scientists collected diet, egg, and nestling tissue samples and analyzed each for of DDT, DDT metabolites, and mercury. These data were then added to the GIS program for comparison with soil contaminant distributions.
The study site has heterogeneous contaminant levels as the result of seasonal flooding and topography modifying the original contaminant deposition areas. The unique design of this project allowed the researchers to control for variables that often confound this type of study. The scientists were able to match foraging areas to specific nesting pairs and use only soil concentration data from the appropriate foraging locations in their analyses of trophic-level transfer of contaminants. The researchers learned that while male and female prothonatory warblers fed at similar rates, the females tended to use larger foraging ranges. They therefore corrected their data to incorporate the feeding areas of both the adult male and female warblers.
The results of this study suggest that residue concentrations in bird tissues can be reasonably predicted from residue concentrations in the soil. The study demonstrated that warblers accumulated renal mercury from their diet at levels that correlated with soil and sediment levels. The researchers also found that soil concentrations of DDT and its metabolites were effective in describing the variation of contaminants in adipose tissues.
The project is an example of the technology transfer process that SBRP strives to promote. Basic experimental methods developed and characterized in the course of SBRP-funded research were successfully deployed in a real world application. The findings of this research were incorporated into ecological risk assessments used in the remedial investigation and the record of decision process prior to the completion of the actual site remediation planning process.
For her critical role in this research and a similar study at the Anaconda Smelter Site in Montana, Ms. Blakely Adair received the 2001 SBRP Karen Wetterhahn Memorial Award which recognizes an outstanding student who studies the environmental or health impacts of metal contamination and best demonstrates the qualities of scientific excellence exhibited by Dr. Wetterhahn. Ms. Adair presented the results of her studies at the 2001 SBRP Annual Meeting.
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