Accumulation and transformation of atmospheric mercury in soil.

Field investigation and simulating experiments were carried out for understanding the accumulation and transformation of mercury in soil in relation to the deposition of atmospheric mercury. A positive correlation between the atmospheric mercury concentration and the content of mercury in soil was observed in the field investigation, with the correlation coefficient being 0.741** (n=52). The mercury content in soil decreased with the increasing distance from the mercury emission source. Simulated experiment demonstrated that the higher the mercury content in air was, the higher was the amount of mercury accumulated in soil, which was in accordance with the results found from the field investigation. Transformation process occurred once mercury deposited into the soil. Analyses of soil samples exposed to air with mercury contents of 796.4+/-186.3 ng/m(3) for 2 months indicated that 24.58-26.86% of total mercury deposited into the soil existed in Hg(0) form, 0.10-0.12% in active form, 14.56-18.75% in HCl-dissoluble form, 0.86-5.84% in organic-bound form and 52.64-55.29% in residual form.