Trace elements usually have unique geochemical behavioural characteristics in karst areas, but in-depth systematic research on heavy metals in karst areas has been lacking. Guizhou province is located in the karst center, south western of China. Rich in mineral resources and characterized by high geological background of trace metals. Therefore, research on micro-interface processes of heavy metal in typical pollution areas of Guizhou can provide scientific basis for prevention and control of heavy metals pollution in Guizhou.

The difference of spatial and temporal distribution of heavy metals in rainfall and surface runoff in Huilong catchment and Chenqi catchment is obviously. The trace elements(Hg、Tl、 As、 Sb、Cd、Pb、Zn and Mn in this work) content of rainfall and surface runoff in Huilong catchment is higher than that in Chenqi, and heavy metal content in the dry season (Oct-Apr) is higher than rainy season (May-Sep). The next step is to combine the rainfall and runoff data to calculate the annual heavy metal input and output fluxes for the two small watersheds. The distribution of heavy metals in soil profiles is quite different. Some elements` distribution trend (such as mercury and thallium in Huilong catchment, R²=0.78) is similar, which may be related to parent rock background, soil formation process and external input. The relationship of trace elements mobility with other parameters (multi-element concentrations in soils, SOM, CEC, pH and redox potential) will be discussed.