University of Maryland - Baltimore County (Ghosh)

Summary

Human health risks associated with the presence of chemicals in sediments arise from either direct contact with the sediments or by eating fish and shellfish that have accumulated chemicals from the sediments. Emerging laboratory-scale research by this group and others has shown that contaminant transport pathways and bioavailability can be interrupted by modifying and enhancing the binding and contaminant assimilation capacity of natural sediments. This is achieved by adding sorbent amendments such as activated carbon for binding persistent organic pollutants and natural minerals such as apatite, zeolites, or bauxite for the binding of toxic metals in sediments. Critical barriers in the adoption of this in situ remediation approach is the availability of efficient delivery methods for amendments to impacted sediments and understanding of physical and biological processes in field sites that control the effectiveness of this technology. The researchers are developing this in situ remediation technology through a pilot-scale investigation aimed at addressing the critical barriers in the advancement of the technology. Field research will be carried out at two PCB/DDT-impacted sensitive wetland sites. The research design will involve application of the technology in a quarter acre plot in each site and a monitoring plan to understand how the fate and transport processes of PCB/DDT in the wetland environment is impacted by the application of the sorbent amendments. Biological monitoring will include PCB/DDT bio-uptake measurements in a freshwater oligochaete carried out in field exposure chambers and also in laboratory microcosms. The physicochemical monitoring will include aqueous partitioning and desorption rate from sediment, two measures that define the bioavailability processes of sediment bound contaminants. The PCB/DDT fate and transport process understanding will be used to assess human health risk benefit from the technology based on a dermal uptake model and a food-chain model. Sediment-bound contaminants such as PCBs and DDT pose a public health risk through contamination of the food chain and through direct exposure. This research will evaluate the effectiveness of a novel approach to alter the binding capacity of sediments to reduce human exposure to such contaminants.