Journal of Hazardous Materials, Vol.131, No.1-3, 19-27, 2006
Solid/solution partitioning and speciation of heavy metals in the contaminated agricultural soils around a copper mine in eastern Nanjing city, China
Solid/solution partition coefficient (K-d) and speciation of soil heavy metals can be used for predicting their environmental risks. The Kd values and solution speciation of soil Cu, Cd and Zn were analyzed in 40 samples of contaminated agricultural soils around Jiuhua copper mine in eastern Nanjing city, China. The K-d ranges (and mean values) for soil Cu, Cd and Zn are 703-7418 (3453), 37.3-3963 (940) and 319-17965 (7244) L kg(-1), respectively, showing a large variability both for metals and soils. The results of differential pulse anodic stripping voltammetry (DPASV) indicates that 95.6% solution Cu is bound to dissolved organic ligands. About half of the dissolved Zn is DPASV-labile at pH < 6, while 92.1% solution Zn is in the form of organic complexes at pH > 6. DPASV-labile Cd is ranged from 22.6 to 98.7% with the mean value of 56.3%. Multiple linear regressions indicate that Kd, the dissolved and DPASV-labile concentrations of Cd and Zn are mostly influenced by the soil solution pH with R-2 of 0.50, 0.59 and 0.63, respectively for Cd, and 0.58, 0.72 and 0.64, respectively for Zn. Considering the second parameter of corresponding soil metal, the linear relationships of Kd with pH were improved with R-2 of 0.70 and 0.73 for Cd and Zn, respectively. However, the solubility of soil Cu was insensitive to pH. Only SOC shows a weak relationship to the dissolved Cu with R-2 of 0.21. As for its K-d, total soil Cu is the most significant factor. But for DPASV-Iabile Cu, no soil parameters were found to be good predictors. (c) 2005 Elsevier B.V. All rights reserved.
Keywords:heavy metal;solubility;partition coefficients (K-d);speciation;differential pulse anodic stripping voltammetry (DPASV);soil solution