hytoremediation of Arsenic from Residential Soils in the Spring Valley Area of Washington, DC (Abstract)

摘要

The residential area of Spring Valley encompasses approximately six hundred sixty- one (661) acres in the northwest section of Washington, D.C. During World War I, at the American University Experiment Station (AUES), the Department of Defense produced the arsenic-based chemical warfare agents, lewisite and adamsite. Chemists and engi- neers tested these agents in the areas surrounding the AUES, which is now known as the Spring Valley residential neighborhood. Investigative soil sampling indicated the pres- ence of arsenic at levels above background and risk-based concentrations. In 2001, the Army Corps of Engineers initiated a removal action to address these areas of concern. The main remediation technology to be applied at residences with elevated arsenic is excavation followed by backfilling with clean soil. This technology, however, can be environmentally disruptive and expensive. Phytoremediation is being considered as an alternative, in sampling grids of Spring Valley with elevated arsenic, to minimize de- struction of existing trees and reduce restoration costs in these residential areas. In 2004, a field verification study was conducted to evaluate the potential of phytoremediation to address the elevated arsenic soil concentrations. The field verification study consisted of two residential areas and one public access area encompassing 14 sampling grids. Three species of ferns, Pteris vittata, P. cretica and P. multifida, were planted and grown from May to November. The 2004 activities were successful in reducing arsenic concentra- tions in the surface soils below target levels in 12 of the 14 sampling grids. Based on these results, the field activities were expanded in 2005 to include a total of 33 sampling grids using approximately 10,000 plants from five different Pteris fern species to evalu- ate the suitability over a wider variety of soil and growing conditions with the goal of removing arsenic from the soil with minimal impact to existing trees, shrubs and other landscape features. The results of the 2005 field demonstration will be presented.