Opportunity at U.S. Environmental Protection Agency (EPA)
Geochemical Processes in Subsurface Systems
National Risk Management Research Laboratory, Groundwater, Watershed & Ecosystem Restoration Division
||Ada, OK 748201198
When solutes are introduced into groundwater systems or into surface waters, complex physicochemical reactions occur between the dissolved solutes and native solid materials. Knowledge of these complex interfacial reactions is required to assess the impact of such inputs on water quality in aquatic and terrestrial ecosystems. Assessments of water quality and efforts to restore contaminated waters depend strongly on a fundamental understanding of geochemical processes involving reactions with mineral surfaces and substrates. Such processes include weathering reactions that contribute dissolved chemicals, sorption that removes aqueous species, and electron transfer mechanisms that establish redox conditions. Knowledge of the geochemical behavior and cycling of major elements, trace elements, and nutrients in terrestrial ecosystems is necessary for understanding and predicting the consequences of deliberate or accidental anthropogenic additions of these substances to the environment.
Specific goals of this program include (1) determining the mechanism and rates of chemical and electron transfer between mineral substrates in soils, surface-water, and groundwater environments; (2) determining the nature and extent of temporal changes in mineral surfaces during weathering and contaminant introduction, and assessing the impact of these changes on subsequent transport and fate of inorganic species; and (3) assessing risk posed by the weathering of toxic materials contained in natural geologic materials and plan mitigation, and cleanup under technical and geologic constraints. Current work has focused on the mobilization of inorganic contaminants from pristine and contaminated geologic materials that are due to biogeochemical reactions active within environments impacted by landfill leachates and contaminated groundwater plumes. A primary component of this research is the development of physicochemical and spectroscopic methods to characterize the in-situ chemical speciation of the inorganic contaminants and other redox-sensitive elements that impact the chemical cycling of the contaminant.
Groundwater; Water pollution; Mineral-water processes; Hydrogeochemistry; Solute transport (hydrologic); Redox reactions; Risk analyses;
Open to U.S. citizens and permanent residents
Open to Postdoctoral and Senior applicants