Environmental effects of heavy metal pollution of farmland soils in gold mining areas

A comparative study was performed of the content of heavy metals in wheat and corn in an area of soil heavy metal pollution and a control area in a certain gold mining area in the Xiaoqingling Mountains. The study shows that: the cumulative contents of Hg,Pb and Cd in wheat seeds in the polluted area are obviously higher than those in the soil control area; there is almost no difference in contents of Cr,As,Cu and Zn between the polluted area and control area; and the above-standard rates of Hg,Pb,Cd,Zn and Cu in wheat are 86.67%,60%,33.33%,6.67% and 20% respectively. In comparison with the control area,the Pb,Cd and Cr contents in corn in the polluted area are markedly high but do not exceed the set standards,only mercury being above the standard,with an above-standard rate of 15.15%. Wheat is easier to absorb heavy metals than corn at the same sampling site. There is a good correlation between the content of heavy metals in wheat and the degree of heavy metal pollution in soils. In contrast with 1990,the cumulative effects of Hg and Cd in wheat are very prominent. The heavy metal pollution of soils in gold mining area has caused serious pollution of wheat.