The U.S. Geological Survey has released a national database of geochemical analyses for 45 major and trace elements at each of 4857 sample sites from across the U.S. The USGS gave us an online briefing of the system and we are just starting to explore the data for Arizona.
According to the announcement the USGS began sampling in 2007 for a low-density (1
site per 1,600 square kilometers, 4,857 sites) geochemical and
mineralogical survey of soils in the conterminous United States as part
of the North American Soil Geochemical Landscapes Project.
protocol for the national-scale survey included, at each site, a sample
from a depth of 0 to 5 centimeters, a composite of the soil A horizon,
and a deeper sample from the soil C horizon. "The resulting data set provides an estimate of the abundance
and spatial distribution of chemical elements and minerals in soils of
the conterminous United States and represents a baseline for soil
geochemistry and mineralogy against which future changes may be
recognized and quantified. This report releases geochemical and
mineralogical maps along with a histogram, boxplot, and empirical
cumulative distribution function plot for each element or mineral."
Highlights of the USGS Soil Chemistry Program – now in public release.
• 4857 sampling sites (1 site/1,600 km2) conterminous U.S.
• Results not unlike a blood test
• Vast improvement on 1960s era nationwide study
• Produce a soil geochem and mineralogical database in conterminous U.S.
• Establish an archive of soil samples.
• Provide background range of elements in soil
• Sampling at 0-5 cm, composite of A horizon, composite of B or C horizon.
• 45 major and trace elements
• 19 mineral species (A and C horizon) – a first for soil survey of this magnitude
• Soil pathogens (0-5 cm depth) – anthrax, plague, hooray!
• Interactive web site in the works – release scheduled next week.
• Data display on Google Earth – Kml files (PDF and GeoTiff, too)
Smith, D.B., Cannon, W.F., Woodruff, L.G., Solano, Federico, and
Ellefsen, K.J., 2014, Geochemical and mineralogical maps for soils of
the conterminous United States: U.S. Geological Survey Open-File Report
2014–1082, 386 p., http://dx.doi.org/10.3133/ofr20141082.
Smith, D.B., Cannon, W.F., Woodruff, L.G., Solano, Federico, Kilburn,
J.E., and Fey, D.L., 2013, Geochemical and mineralogical data for soils
of the conterminous United States: U.S. Geological Survey Data Series
801, 19 p., http://pubs.usgs.gov/ds/801/.