The distribution characteristics of methyl mercury in Rana chensinensis and water,sediment and soil in gold-mining areas of the upper reaches of the Songhua River,China were studied by field sampling and laboratory testing.The results show that the methyl mercury contents in water,sediment and soil in gold-mining areas are much higher than those in the control site,indicating that gold-mining activities intensify the methyl mercury pollution in the study area.Methyl mercury contents are in a descending order of sediment > soil > water in the environment,and in a descending order of brain > viscera > muscle > skin in Rana chensinensis.There are significant correlation between methyl mercury contents in Rana chensinensis and those in water and sediment.In particular,the methyl mercury content in the skin of Rana chensinensis is positively correlated with those in water and sediment in spring.Therefore,skin is one of main intake pathways for methyl mercury due to its high permeability.
The single toxicity of cadmium（Cd） or 9 substituted phenols to Phtobacterium phosphoreum was determined, respectively. The results indicate that the single toxicity was related to group variety, group sum and substitutive positions. On the basis of single toxicity, the joint toxicity of Cd and 9 substituted phenols was measured. The result indicates that the joint toxicity was basically a simple addition of the single toxicity of them or close to simple addition of the single toxicity of them. QSAR equations were built from the joint toxicity and molecular structural descriptors of substituted phenols under the different Cd concentrations. It was shown that the joint toxicity under different Cd concentrations was related to the identical descriptors, the logarithm of n-octanol/water partition coefficient（lgP） and the heat of formation（△Hf）, with R2=0.855, 0.878 and 0.780, respectively. Good agreement between the predicted and observed values was found with R2=0.837.
SU Li-min YUAN Xing MU Chun-fang YAN Ji-chang ZHAO Yuan-hui
