Abstract: The optimized Tessier sequential extraction procedure (SEP) method was used to analyze the speciation and bioavailability of mercury (Hg) in pollution soils of Wanshan mercury mining area, Guizhou Province. The results indicated that the concentration of Hg in rice paddies was dominated by residual fraction (79.65%), followed by organic bound fraction (19.97%), oxide bound fraction (0.31%), specifically sorbed fraction (0.04%) and exchangeable fraction (0.03%). The content of mercury species in soil samples were found to decrease with distance increasing from pollution sources, except specifically sorbed fraction; the proportion of bioavailable (exchangeable fraction and specifically sorbed fraction) mercury was very low in contaminated area, but the content was obviously higher than those in reference soil.

Key words: Slopeland, Effect of soil water and fertilizer, Water use efficiency, Loess soil