Abstract: A pot experiment with simulated rainfall was conducted to study the mitigation effects of Vetiveria zizanioides and additives (sawdust and humus soil) on the surface runoff mercury concentration from Hg-contaminated soil and slag. In the surface runoff, particle mercury accounted for 80% of the total mercury, being the leading form of mercury transported to environment. Planting V. zizanioides on the Hg-contaminated soil or applying V. zizanioides mixed with sawdust or humus soil into the contaminated soil could effectively reduce the total mercury, particle mercury, and dissolved mercury transportation to environment by 63%-85%, 63%-85%, or 27%-73%, respectively, and the effect was significantly higher than that of applying single sawdust (5%) or humus soil (23%) into the contaminated soil. Applying background soil or sawdust into the Hg-contaminated slag, planting V. zizanioides on the slag, or applying V. zizanioides mixed with background soil, sawdust, or humus soil into the slag could effectively fix the total mercury, particle mercury, and dissolved mercury in slag by 29%-82%, 27%-84%, or 20%-70%, respectively.

Key words: Biogeochemistry, Grassland ecosystem, Storage, Biogeochemical cycle