ROLE OF PEACE CORPS NEPAL VOLUNTEERS IN THE UNITED STATES GEOLOGICAL SURVEY SOUTH ASIA ARSENIC PROJECT

Hundreds of thousands of people in Nepal drink water with high concentrations of arsenic, because they have no alternative. To address this problem, the USGS South Asia Arsenic Project conducts geohydrological and geochemical investigations in areas where natural arsenic concentrations in groundwater exceed drinking water standards (50 ppb). Our investigations in Bangladesh and Nepal, through collaboration with national government agencies, try to examine distribution of arsenic contaminated aquifers, determine cause of contamination, and evaluate suitability of alternative aquifers to be sustained sources of safe water. In Nepal, Peace Corps Volunteers work with Nepal Department of Water Supply and Sanitation officials to make field measurements of arsenic concentration in the water from thousands of village hand pumps, collect GPS position data for each well, create a database, and use it to make statistical analyses. This data plotted in a GIS revealed several hotspots with concentrations consistently above 400 ppb and indications of a maximum at about 20 m depth. This information was invaluable in guiding the USGS drilling program to collect sediment core samples from contaminated aquifers. A USGS field geologist for the project provides an additional connection to Peace Corps through his service in Peace Corps Nepal, Group 10 (1966-69). During Spring 2003, the USGS team collected more than 200 samples of sediment from the most contaminated aquifers in Nepal. Preliminary analyses of the sediment have verified differences in composition related to redox conditions. Gray sediment typically has greater 0.5 N extractable Fe²⁺/Fe_total, total sulfur and organic carbon than adjacent brown sediment. These differences, however, are not related simply to arsenic abundance in the sediment or ground water.