SUBSURFACE OCCURRENCE, FATE, AND TRANSPORT FACTORS ASSOCIATED WITH ARSENIC IN SHALLOW GROUNDWATER AT SEVERAL RURAL LOCATIONS IN THE SOUTHEASTERN U.S

Approximately 140 million people in scores of countries, including the U.S., are currently at risk of exposure to dangerous concentrations of arsenic in their drinking water supplies. While arsenic is a well known and potent poison at high levels of exposure, long-term ingestion of arsenic at much lower concentrations (>10 μg/L in water) has been scientifically linked to numerous diseases and maladies, including various cancers. Some arsenic contamination problems can be traced back to releases associated with manmade activities and chemicals, though most of the arsenic found in groundwater appears to originate from the weathering of naturally-occurring source materials. In nearly all countries with arsenic contamination issues, groundwater consumers in rural areas are generally considered to be at greater risk of exposure due to the fact that (1) wells are relied upon more heavily for water supply in these areas and (2) local treatment options are frequently very limited or nonexistent. Arsenic occurrence and mobility in aquifers in these higher risk areas are constrained by various factors, including the mineralogy and weathering history of source materials, local subsurface redox conditions, etc. This study examines arsenic sample results from shallow monitoring wells in several rural regions of the southeastern U.S. and attempts to associate occurrence, fate, and transport of the contaminant with obvious geological and geochemical factors.