XRF ANALYSIS OF TRACE ELEMENTS IN SOILS SURROUNDING A COAL-FIRED POWER PLANT, POSEY COUNTY, SOUTHWESTERN INDIANA

Our research uses a PANalytical X-ray Fluorescence (XRF) Spectrometer to conduct a trace element analysis to identify potential chemical contaminants in soils surrounding a coal-fired power plant near the campus of the University of Southern Indiana. 18 upland forested soils were collected from sites within an 8 Km (5 mi) radius of the power plant. The sites were selected to minimize the influence of agricultural and roadway inputs and avoid homogenizing effects of lowland fluvial systems. Soils were sampled at ~ 30 cm (1 ft) intervals within the A and B-horizons to a depth of ~ 1 m (3 ft). Initial data indicates concentrations ranging from 0 to 130 ppm for As, Pb, Cr, Co, Cd and Se that are known to cause adverse health effects when concentrations exceed established guidelines. The EPA reports naturally occurring concentrations (in ppm) of As, Pb, Cr, Co, Cd, and Se in surface soils range from 1-50, 1-1,000, 2-200, 0- 50, 0.6-1.1, and 0.1-2 respectively. Our data (in ppm) shows ranges of 70-80 (As), 0-100 (Pb), 45-90 (Cr), 20-30 (Co), 0-15 (Cd), and 0-13.5 (Se), with values commonly exceeding naturally occurring levels of trace elements. This indicates an external source is contributing to the higher than background level trace element concentrations. Contour maps of available concentration data (e.g., Pb) for the study area demonstrate a pattern with a southwest to northeast trend, aligned with persistent surface winds, and with notable concentration peaks at 2.5 to 5 km (1.5 to 3 mi) downwind of the coal-fired power plant. Given our requirements for sample site placement, and the orientation and alignment pattern of concentration contours with surface winds, it appears the nearby power plant is a potential source of the trace element contaminants, either from the smokestacks or from on-site fly ash pits. The power plant’s scrubbers are not 100% efficient at capturing pollutants, and on-site fly ash storage is known to become airborne. Therefore, either of these mechanisms could be contributing to the increased concentration of the studied trace elements in the study area.