Soil contamination and sources of heavy metals at individual sites of industry and mining associate with wastewater irrigation in China
我国几个工矿与污灌区土壤重金属污染状况及原因探讨

An investigation on soils contaminated with heavy metals was carried out at heavy industrial areas, metal mining and tilling sites, and farmland with sewage water irrigation, respectively. The result indicated that concentrations of the most metals from the polluted sites were higher than those from backgrounds, Cd and Zn should be paid more attention since they were over the Governmental Standards in China for limitation of soils in agricultural practices. Some companion relations existed between various metals, such as Pb and Ni, Cr with Ni and Zn, Cu with Zn and Ni, the negative correlation between extractable contents of Cd and Zn and soil pH values was found. The soil metals mainly come from untreated sewage water irrigation, disposal of tailings or slurry from metal ore mining. Besides, metal dust deposition was one of the contributors as well in the vicinity of metal smelters or heavy industrial areas since a good exponential correlation ( R \+2>0 9) between the contents of Pb, Zn or Cd and the distances from the source existed.