THE U.S. GEOLOGICAL SURVEY’S NATIONAL GEOCHEMICAL DATABASE

The U.S. Geological Survey’s (USGS) National Geochemical Database (NGDB) contains inorganic chemical analyses for approximately 2 million samples of geologic material collected since the early 1960s. The primary sample media represented in the database are unconsolidated sediments (from streams and lakes), rocks, and soils, with fewer analyses of plants, water, organic fuels (primarily coal), and other media. The NGDB, in reality, consists of three separate databases. Two of these, RASS and PLUTO, contain data generated by the analytical laboratories of the USGS Geologic Discipline and the third consists of data generated during the Department of Energy’s National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) Program conducted from the mid-1970s through the early 1980s. Approximately 65-70 percent of the United States currently has some degree of sample coverage represented in the NGDB. Unfortunately, not all of the samples were collected and analyzed using the same protocols. Nevertheless, the NGDB represents a potentially valuable resource for earth scientists, environmental geochemists, and those involved in ecological or human health risk assessment. Efforts are currently underway to improve the quality of the NGDB through a systematic upgrading of the information concerning sample collection protocols, sample preparation methods, and analytical techniques. The upgraded and reformatted NURE HSSR data may be downloaded from the following URL: http://pubs.usgs.gov/of/1997/ofr-97-0492/index.html. The remainder of the NGDB will be placed on a web site within the next 1-2 years.