AGS / Geology / Geochemistry / Arkansas Geochemical Survey
Arkansas Regional Geochemistry of Soils and Stream Sediments, a Portion of the National Geochemical Survey
J. Michael Howard, Principal Investigator
The AGC Soils and Stream Sediment cooperative project was funded by Grant No. 03ERAG0057 from the US Geological Survey (USGS), as part of the National Geochemical Survey. The purpose of the project was to complete sampling that was done decades before by the Federal Nuclear Regulatory Commission. By the mid-1960’s, approximately 50 percent of Arkansas had been sampled and the NURE data published. However, new funding became available after 2000 to complete the work nationally. The grant for the work in Arkansas provided $20,000 to pay for field and equipment expenses. Soil and stream sediment samples were collected from 100 mi2 grid across Arkansas and analysis for 55+ elements is on-going by the USGS Chemistry Laboratory. Their final product will be a series of Internet interactive geochemical maps reflecting baseline element values.
For Arkansas, this project consisted of field collection of both soil and stream sediments samples, storage and air drying of the samples, and shipping them to the USGS Chemistry Laboratory warehouse in Denver. The field collection began in December of 2003 and was completed in December 2004. Final samples were shipped in February 2005. For Arkansas, 1,149 sample records lie within the state.
Analytical work by the USGS is on-going. However, a significant portion of data is now posted online and is available to the public. All posted geochemical analyses for Arkansas may be downloaded from the US Geological Survey web site free of cost at: http://tin.er.usgs.gov/geochem/doc/home.htm.
Sample collection both nationally for the NGS project and in Arkansas are presented below. Arkansas’ samples consist of two types: stream sediments and soil samples. Soil samples consist of both an upper and lower horizon.
Sample density, depicted below, is the number of samples within a given area.
A Periodic Table of the Elements displayed below is color coded for those elements for which analyses will eventually be completed (green) and those which will not be analyzed (pink). This chart is posted as an interactive chart on the USGS website.
Data quality for elements summarized below is subdivided into the following general groupings: excellent, very good, good, poor, and variable. An explanation of these terms and their derivations is given on the USGS web site at: http://tin.er.usgs.gov/geochem/doc/data-quality.htm .
For Arkansas, county-by-county elements mean & standard deviation values are available as interactive online maps at:
http://tin.er.usgs.gov/geochem/doc/averages/countydata.htm for the following elements: Aluminum (Al), Arsenic (As), Calcium (Ca), Copper (Cu), Iron (Fe), Lead (Pb), Mercury (Hg), Magnesium (Mg), Manganese (Mn), Phosphorus (P), Selenium (Se), Sodium (Na), Titanium (Ti), and Zinc (Zn). Additional elements will be added to this listing as they become available.
Also, discrete county data for all of Arkansas, along with graphic plots of sample sites, may be viewed or downloaded from the USGS web site at:
Summary maps with basic analytical and instrumental data are available on the AGS website by clicking each of the following elements: Aluminum (Al), Arsenic (As), Barium (Ba), Beryllium (Be), Calcium (Ca), Cerium (Ce), Chromium (Cr), Cobalt (Co), Copper (Cu), Gallium (Ga), Gold (Au), Iron (Fe), Lanthanum (La), Lead (Pb), Lithium (Li), Magnesium (Mg), Manganese (Mn), Mercury (Hg), Neodymium (Nd), Nickel (Ni), Niobium (Nb), Palladium (Pd), Phosphorus (P), Platinum (Pt), Potassium (K), Scandium (Sc), Selenium (Se), Sodium (Na), Strontium (Sr), Thorium (Th), Titanium (Ti), Vanadium (V), Yttrium (Y), Zinc (Zn) .
Graphics for this article were downloaded and modified by the author from the USGS web site.