In 1976, the U.S. Geological Survey (USGS) began studies of unsaturated zone hydrology at a site in the Amargosa Desert near Beatty, Nevada, as part of the USGS Low-Level Radioactive Waste Program. The site is near disposal trenches for civilian waste.

Over the years, USGS investigations at the Amargosa Desert Research Site (ADRS) have provided long-term "benchmark" information about the hydraulic characteristics and soil-water movement for both natural-site conditions and simulated waste-site conditions in an arid environment. In 1995, as a result of finding elevated concentrations of tritium and carbon-14 in the unsaturated zone beneath the ADRS, the scope of research was broadened to include the study of processes affecting transport of contaminants through the unsaturated zone. The ADRS was incorporated into the USGS Toxic Substances Hydrology Program in 1997. The site serves as a field laboratory for multidisciplinary, collaborative research that involves scientists from research institutes, universities, National laboratories, and the USGS.

Current Research

Field-intensive research on water, gas, and chemical movement through the unsaturated zone is being supported by multiple lines of data:

• Weather, evapotranspiration, and plant data
• Subsurface moisture, temperature, gas, and ground-water monitoring
• Soil and sediment properties; geology; geophysics; and microbiology

Contaminants studied include

• Tritium
• Radiocarbon
• Volatile-organic compounds
• Mercury

Perchlorate systematics:

• Soil, plant, and bulk-deposition samples are being used to evaluate factors controlling accumulation of natural perchlorate in desert environments.

Field and laboratory data are being integrated with numerical modeling to develop predictive tools for assessing chemical transport and fate in the environment.

Methods are being developed to improve characterization of physical, chemical, and biological factors that control hydrologic and chemical-transport processes.