Spatial distribution of smelter emission heavy metals on farmland soil.

This work was conducted to explore heavy metal pollution in soils in an area near lead smelters in Jiyuan City, which is one of the main lead production areas in China. Altogether, 88 topsoil samples (0-20 cm) were collected from farmlands near the Yuguang lead smelting facilities; the sampling sites were 1570 to 6388 m to the main stack of the Yuguang. Analysis of the samples indicated that (i) the ranges of total Cd and Pb concentrations were 0.81-4.30 and 64.5-435 mg kg-1, respectively, mean pollution indices (concentration in soil/background value, PI) were 32.8 and 9.11, respectively, and the concentrations of total Cu, Zn, and Ni were slightly higher than the background values. Mean concentrations of DTPA-extractable Cd and Pb were 0.752 and 58.7 mg kg-1, respectively. (ii) The total concentrations of Cd, Pb and Pb/Cd ratios of samples decreased as the distance to the main stack of the Yuguang increased. Abnormal variations of these trends suggested these parameters of certain samples were affected by pollution sources other than the Yuguang. (iii) Judged by the results of this work, the area of the heavy metal-polluted land in Jiyuan was much greater than 115 km2, a value reported by an earlier investigation. These results indicate that the soil in the study area was polluted by Cd and Pb emissions from more than one polluting sources, the variation of Cd, Pb concentration and Pb/Cd ratios of samples to the distance of the pollution source can be potentially used for pollution source identification.