Exposure Pathways

Shallow ground waters in northern climates often have temperatures below 10° Celsius (C) [50° Fahrenheit (F)] during the winter season. The ability of microorganisms to degrade contaminants under these conditions has long been questioned by the scientific community because microbial activity often decreases with decreasing temperatures and because rates of biodegradation typically are assumed to...

U.S. Geological Survey (USGS) scientists completed a variety of groundbreaking studies on the occurrence, fate, and transport of triazine herbicides and their degradates throughout the 1990s. The results of these studies have been summarized and condensed into a USGS report and a book chapter providing, for the first time, a comprehensive snapshot of a decade of this research.

U.S. Geological Survey (USGS) scientists continue to develop and adapt new geophysical technologies and data analysis methods for monitoring the performance of remediation systems and for the characterization of contaminated sites. Geophysical monitoring methods are particularly adept at measuring changes in subsurface properties that relate to the presence of water, tracers, contaminants, and...

Since the late 1990s, the U.S. Geological Survey (USGS) has conducted an Abandoned Mine Lands (AML) Initiative . The initiative provides technical assistance to support actions by Federal Land Management Agencies in the U.S. Department of the Interior and the U.S. Department of Agriculture (USDA) to remediate contamination associated with abandoned hard-rock mining sites. Acid drainage and toxic...

U.S. Geological Survey (USGS) scientists have discovered that rainwater recharging the water table above petroleum contamination plumes affects how plumes grow and the rate that petroleum products (in this case crude oil) degrade and weather in ground water. The amount of recharge affects the migration of oil in the subsurface, how chemicals dissolve from the oil into ground water, and the...