Mobility of Metals from Fly Ashes and its Potential Impact on Surface Water Quality in Guizhou Province, Southwestern China

Abstract

In order to evaluate the impacts of metals mobility from fly ashes on surface water quality, the dissolved metals concentrations in the stream and pond waters nearby fly ash piles were investigated at the thermal power plant regions in central Guizhou Province, and batch leaching or column leaching tests for the fly ashes were performed. The results shown that the most mobile of the metals leached were Cu, Cr, Pb and Cd from fly ashes and the concentrations of the metals in leachate solutions increased with the amount of fly ashes, and high concentrations of Pb (0.040~0.886 mg L−1), Cr (0.025~0.315 mg L−1) and Cd (0.007~0.052 mg L−1) in the leachates from fly ashes, and then there is an mobility of dissolved metals to the surface waters impacted by the runoff or leaching water. In thermal power plant areas, the concentrations of Pb, Cr and Cd in the stream waters and the pond waters nearby fly ash piles were 0.024~0.374 mg L−1, 0.030~0.212 mg L−1 and 0.014~0.035 mg L−1, respectively, as indicated by high concentrations of Pb, Cr and Cd, making it unsuitable for human drinking, suggesting a environmental problem of runoff or leaching water from fly ash pile in those areas.