Proton-induced X-ray emission measurements of trace elements in water samples collected from an Indiana coal mining locality

A new method of simultaneous multi-elemental analysis, Proton Induced X-ray Emission (PIXE), was used to detect trace elements in waters associated with a coal strip-mining operation in southern Indiana. Stream, pond, and ground water samples were collected and analyzed monthly from, or near, Sulphur Creek in Sullivan County. The concentrations of 26 major and trace elements were determined in samples from eleven locations: K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Mo, Cd, Sn, Sb, I, Ba, Hg, Pb, and U. Elemental concentrations fluctuated considerably throughout the 13-month sampling period and also among sampling sites. Nickel, Zn, As, Cd, Mn, Fe, and Ca were highest in the upstream water which was most acidic (pH = 2.9–4.0) because of old unreclaimed mining operations. The highest values recorded were Ni = 1662 ppb, Zn = 4953 ppb, As = 26 ppb, Cd = 93 ppb, Mn = 5063 ppb, Fe = 63 ppm, and Ca = 325 ppm. The concentrations of these elements decreased downstream as the pH of Sulphur Creek increased which was likely due to the influence of the calcareous glacial till cover in the area and the recent mining activity which disturbed overburden containing a high percentage of calcareous materials. Lead, I, Br, and Ti values were highest (661 ppb, 86 ppb, 70 ppb, and 45 ppb, respectively) in the ground water from the coal seam (pH approximately 7). Other elements which were relatively high in the pH 7 waters closest to the current mining operations (pond, stream, and groundwater) included K (17 ppm), Sr (3408 ppb), Ba (173 ppb), As (14 ppb), Rb (16 ppb), Sn (14 ppb), and Cu (3840 ppb). The highest Cu concentration was recorded at the point where drainage water from the mine entered Sulphur Creek. Gallium, U, Hg, and Mo were found in low (< 13 ppb for Ga and Hg; < 205 ppb for Mo and U) concentrations and only in the ponds within the mine.