Study on temporal and spatial variation of Hg cumulative effect of farmland soil in Tongguan Goldfield

Hg contents of 133 samples from the plough layer soil over Tongguan Goldfield were employed to explore the Hg cumulative effect and its characteristics in temporal and spatial variation via corporative evaluation. The results show that the Hg contents in the soil varied from 0.04 mg/kg to 61.2 mg/kg, its arithmetic mean value was 22.92 times that in its adjacent region. 94% samples were over-standard of the comparison value, while 54% samples exceeded the comparison value by more than 7.28 times. Obviously, there was a cumulative effect of Hg in the studied soil. The most serious effect was observed in the east area, especially along two north-south belts. The cumulative effect was also gotten more serious from 1989 to 2009 through analyzing the data of 9 sample points. Hg was added in the gold mineral processing and resolutely was presented in the tailings, and formed the most primary source for Hg in the studied soil.