Leaching of Arsenic, Chromium, and Copper from Coal Fly Ash Treated Soil

The use of coal fly ash for soil amelioration may provide soil enrichment as well as the disposal of fly ash produced from thermal plants. However, when exposed to rainfall, hazardous elements such as arsenic, chromium, and copper in the coal fly ash may be released into the soil and cause environmental pollution. In the current study, continuous leaching experiments were performed on coal fly ash used as a soil ameliorant to investigate the leaching of arsenic, chromium, and copper. The concentrations of the analytes and other elements in leachates from fly ash were determined by inductively coupled plasma mass spectroscopy and X-ray fluorescence spectrometry, respectively. The results indicated that the concentrations of these leached elements varied depending on the distance from the amended soil. In the downstream soil, the concentrations of arsenic and chromium increased with distance of the amended soil. However, the concentration of copper initially increased and then decreased under the same conditions. The maximum average concentrations of arsenic and chromium were three times and five times higher, respectively, than the corresponding background values in water. Moreover, the concentration of arsenic decreased with leaching time in the order of 14 > 2 > 8 h, while the concentrations of chromium and copper decreased according to 2 > 8 > 14 h. These results provide useful information for the safe utilization of coal fly ash