Science Inventory

Description:

The discharge of groundwater into surface water may influence the concentrations and availability of contaminants in sediments. There are three predominant pathways by which groundwater may affect the characteristics of contaminated sediments: 1) direct contribution of contaminants from the discharge of contaminated groundwater, 2) indirect influence on existing contaminants due to goelogic and chemical processes that change the properties of sediments and contaminants, and 3) indirect influence on existing contaminants due to the influence of groundwater discharge on biological (e.g., microbial) processes that transform or degrade contaminants. Groundwater can act as a conduit for dissolved pollutants and sediment constituents. With an enhanced understanding of groundwater discharge to surface water systems, scientists can improve estimates of long-term contaminant loads in sediments and develop better management practices to control human and ecosystem exposure to contaminated sediments. An overview of this technical issue will be provided, along with results from two field research projects conducted by the Office of Research and Development in cooperation with EPA Region 1 Office. These case studies will be used to illustrate three topics: 1) identification of links between groundwater discharge and sediment contamination with emphasis on arsenic, lead and zinc, 2) development of new approaches to identify spatial variability of groundwater discharge into surface-water systems using direct measurements and cost-effective surrogate measures, and 3) use of research findings by EPA Region 1 to identify the impact of groundwater discharge on metal contamination in sediments, and to select cost-effective remedies to manage contaminant inputs at two Superfund sites.

Purpose/Objective:

To illustrate the impact of groundwater discharge on contaminant behavior in sediments.

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