Major and trace element concentrations in surface organic layers, mineral soil, and white oak xylem downwind from a coal-fired power plant

Abstract

White oak (Quercusalba L.) xylem tissues, associated mineral soils (0 to 25 cm), and surface organic layers (O2 horizon) were sampled downwind from a 623 MW coal-fired power plant to determine whether major or trace element concentration patterns were affected by changes in emission stack heights during a 32-year operating period. Four sites with Hazleton (Typic Dystrochrept) soils located at 0.25, 1.2, 2.0, and 10.3 km downwind from the power plant were sampled. In surface O2 layers, Fe and Co concentrations varied inversely with distance from the power plant. Inductively coupled plasma–atomic emission spectroscopy was used to determine concentrations (ppm) of P, K, Ca, Mg, Fe, Mn, B, Na, Sr, Ba, Cu, Al, Si, Cr, Ni, Co, Pb, and Cd in xylem tissues during four separate time periods: one preoperation and three periods concurrent with power plant operation. Only Sr concentrations showed a consistent pattern of greatest accumulation in the xylem during periods when emission stacks were lowest, and at sites closest to the power plant. Potentially toxic elements were not detected at elevated levels in xylem tissues; however, xylem Sr may be a sensitive bioindicator of historical fly-ash deposition.