The effects of soil composition on human and ecological health are well documented. Soil can be a pathway for potentially toxic elements of natural or anthropogenic origin to enter the human or animal body through ingestion, inhalation, or dermal absorption and to enter plants by absorption through root tissues. A soil geochemical survey was conducted in the WLCI study area in southwest Wyoming as part of the long-term monitoring objective of this project. The primary purpose of the survey was to determine the abundance and spatial distribution of 44 chemical elements in soil. Such baseline information is needed by land managers to aid in recognizing and quantifying changes in soil composition caused by either anthropogenic or natural processes. The resulting data set also can be used to estimate possible risks to humans and other biological receptors (for example, plants or birds) from exposure to potentially toxic elements in soil.
During the 2008-2010 field seasons, soil samples were collected from 175 sites (one site per approximately 440 km2) in the WLCI study area. Sampling sites were selected at random in a manner that ensured relatively uniform spatial distribution throughout the study area. Each sample was collected from a depth of 0-5 centimeters and analyzed for aluminum (Al), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), sodium (Na), sulfur (S), titanium (Ti), silver (Ag), arsenic (As), barium (Ba), beryllium (Be), bismuth (Bi), cadmium (Cd), cerium (Ce), cobalt (Co), chromium (Cr), cesium (Cs), copper (Cu), gallium (Ga), mercury (Hg), indium (In), lanthanum (La), lithium (Li), manganese (Mn), molybdenum (Mo), niobium (Nb), nickel (Ni), phosphorus (P), lead (Pb), rubidium (Rb), antimony (Sb), scandium (Sc), selenium (Se), tin (Sn), strontium (Sr), tellurium (Te), thorium (Th), thallium (Tl), uranium (U), vanadium (V), tungsten (W), yttrium (Y), and zinc (Zn). In FY2012, risk to humans and four groups of biological receptors (plants, soil invertebrates, birds, and mammals) was estimated by comparing element concentrations revealed in this study (if they met certain statistical parameters for those elements) with soil-screening levels established by the U.S. Environmental Protection Agency for both human health and ecological systems. Two types of maps were prepared to convey this information: (1) maps showing whether individual sampling sites within the WCLI study area exceeded the screening levels; and (2) maps showing the probability of exceeding a soil screening level at any point throughout the entire study area.
Products Completed in FY2012
- Maps showing sampling sites within the WCLI study area that exceeded the Environmental Protection Agency’s (EPA) ecological soil screening levels for (1) As, Co, Mn, Ni, Se, and Zn (plants); Ba, Mn, Se, and Zn (soil invertebrates); Cd, Cu, Pb, Se, V, and Zn (birds; see fig. 7 for example); Ba, Cd, Sb, Se, and Zn (mammals); and (2) human-health soil screening levels for As, Co, and Mn.
- Maps showing the probability of exceeding the EPA ecological soil screening levels at any point throughout the entire WLCI study area for (1) As, Mn, and Zn (plants); Ba, Mn, and Zn (soil invertebrates); Cd and Zn (birds; see fig. 8 for example); Ba, Cd, Sb, and Zn (mammals); and (2) human-health soil screening levels for As and Mn (that is, the subset of elements found in samples that met certain statistical parameters).
- Smith, D.B., Potentially toxic elements in soils of the Wyoming Landscape Conservation Initiative Study area -- Implications for ecological and human health (submitted in January 2012 to the WLCI Integrated Assessment authors for possible inclusion of text, tables, or figures in the assessment report).
Products Completed in FY2011
- Smith, D.B., and Ellefsen, K.J., 2010, Soil geochemical data for the Wyoming Landscape Conservation Initiative Study Area: U.S. Geological Survey Data Series Report 510, 12 p., revised September 2011, available online at: http://pubs.usgs.gov/ds/510/.
- Forty-seven geochemical maps showing the abundance and spatial distribution within the WLCI study area for all 47 soil parameters in the data table published in Smith and Ellefsen (2010).
- Exploratory data analysis plots, including histograms, Tukey boxplots, empirical cumulative distribution function plots, and quantile-quantile plots for the following elements from 0 - 5-cm soils from the WLCI study area: Al, As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, carbonate C, organic C, Cu, Fe, Ga, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Th, Ti, Tl, U, V, W, Y and Zn.
Products Completed in FY2010
- Smith, D.B., and Ellefsen, K.J., 2010, Soil geochemical data for the Wyoming Landscape Conservation Initiative Study Area: U.S. Geological Survey Data Series Report 510, 10 p., available online at: http://pubs.usgs.gov/ds/510/.
- Map showing location of all 175 soil sampling sites within the WLCI study area.
Products Completed in FY2009
- Geochemical data set listing determinations for the following 47 parameters from 139 samples of soil collected from a depth of 0-5 cm within the WLCI original study area: Al, As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, carbonate C, Cu, organic C, Fe, Ga, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Th, Ti, Tl, U, V, W, Y, Zn, total N, soil pH, electrical conductivity, and sodium adsorption ratio. Forty-seven geochemical maps showing the abundance and spatial distribution within the original WLCI study area for all 47 soil parameters in the database described in the bullet above.
- Exploratory data analysis plots, including histograms, Tukey boxplots, empirical cumulative distribution function plots, and quantile-quantile plots for the following parameters from 0-5-cm soils collected within the original WLCI study area: Al, As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, carbonate C, Cu, organic C, Fe, Ga, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Th, Ti, Tl, U, V, W, Y, and Zn.
