Extractability and leachability of Pb in a shooting range soil amended with poultry litter ash: investigations for...

The use of agricultural and industrial by-products as a metal immobilizing agent is cost effective for remediation of vast amounts of contaminated soil. The objective of this study was to assess the effect of an amendment (poultry litter ash) on immobilizing Pb in a shooting range soil. For a contaminant transport study, the soil admixed with amendment at the rate of 0 (control), 0.5, 1, 3 and 6%(w/w) was packed into soil columns and eluted solutions were collected through 40 pore volumes. The amendment application significantly reduced the concentrations of water-extractable and toxicity characteristic leaching procedure (TCLP)-extractable Pb by > 96% and > 97% of control, respectively. The contaminant transport study demonstrated that increasing amendment additions up to 3% decreased eluted Pb concentration below 0.5 mg L(-1). The X-ray diffraction peaks indicative of chloropyromorphite were observed in the soil of the 1 and 3% treatments, but were less intense in the 0.5 and 6% treatments. The 6% treatment had an eluted Pb concentration of 13 mg L(-1) at the first pore volume and significantly increased the total Pb elution (38 mg kg(-1)), mainly due to a drastic increase of organically complexed Pb as a result of soil alkalinization. These results suggest that poultry litter ash may have potential for immobilizing Pb in shooting range sites, if the soil pH is properly managed.