Site on the Chlorofluorocarbon Laboratory and its analytical services for CFCs, sulfur hexafluoride, dissolved gases including nitrogen, argon, methane, carbon dioxide, oxygen, and helium, and tritium/helium-3 dating.
The USGS Luminescence Dating Laboratory in the Denver Federal Center, Colorado, is a facility for determining the age of sedimentary and volcanic ash deposits using luminescence dating with information on sample collection and laboratory methods.
Overview of the Toxic Substances Hydrology Program role in investigating the occurrence and fate of agricultural chemicals with links to investigations, headlines, on-line fact sheets, new publications, bibliographies and photo gallery.
Using genetic analysis of organic material found in aquatic environments it is possible to detect the presence of organisms without necessarily observing or capturing individuals. Explains terms, methods, and prospective utility of this approach.
Well vulnerability results from the young age of groundwater. Karst features permit contaminants to move into the aquifer easily, leading to a well mixed aquifer; geochemical processes do not degrade contaminants quickly.
Using ground-water geochemical analyses, and mathematical models, the factors affecting the quality of public water supply were identified as pumping schedule, screened interval, past land use within the recharge area, and natural geochemical conditions.
Using ground-water geochemical analyses and mathematical models, the factors affecting the quality of public water supply were identified as mixing of very recent recharge with older water, karst features, natural geochemical processes, and pumping.
Maps and text (Word or PDF format) and database (Excel or HTML format) for bedrock, forest floor, and mineral soil sampling in Voyageurs National Park, Minnesota to establish the background and baseline geochemistry and terrestrial mercury sources.