Abstract: A study of the daily event precipitation in Guiyang was taken between July and September, 2008. The average concentration of total Hg (THg) in daily event precipitation was 18 ng·L^-1 with a range from 0.4 to 57.4 ng·L^-1; the average concentration of methyl Hg (MeHg) in daily event precipitation was 0.07 ng·L^-1, with a range from 0.02 to 0.2 ng·L^-1. The main inorganic ions were SO^2-₄, NO^-₃, Ca²⁺, NH₄⁺, and Mg²⁺. The average concentrations of SO^2-₄ and NO^-₃ were 151 mol·L^-1 and 145 mol·L^-1, respectively. The average concentration of Ca²⁺ was 123 mol·L^-1 with a range from 3.7 mol·L^-1 to 560 mol·L^-1. The average concentrations of NH₄⁺ and Mg²⁺ were 52.2 mol·L^-1 and 20.4 mol·L^-1, respectively. According to the relationships between the concentrations of THg and inorganic ions, we identified that the possible sources were fossil fuels burning.

Key words: Chlamys farreri, Biodeposition method, Clearance rate, Absorption efficiency, Element budget