Research at the Environmental Protection Agency's Ecosystems Research Division (ERD) "includes studies of the behavior of contaminants, nutrients, and biota in environmental systems, and the development of mathematical models to assess the response of aquatic systems, watersheds and landscapes to stresses from natural and anthropogenic sources." The ERD website contains information about a wide variety of research foci including: Nitrogen and Redox Speciation in Environmental Systems; Lock Lake Tidal Marsh Study; Exposure Analysis Modeling System; Oil Spills; Brownfields, and more. The site offers a collection of downloadable publications and fact sheets and lists complete publications from 1995 onward as well. Site visitors will also find contact information for staff, presentation abstracts, information about various research opportunities, and a link to available ERD software.