Abstract: 【Objective】To investigate the release patterns of heavy metals in the soils around tailings in western Inner Mongolia.【Methods】The leaching release characteristics of heavy metals Cu,Zn,As and Pb in the soil around tailings in Bayannur City,Inner Mongolia were investigated by leaching experiments. Four treatments,0（CK）,1%,2% and 3% humic acid addition were set up. Heavy metal leaching kinetics experiments were carried out using column leaching apparatus,then fitted with the first order kinetic equation,modified Elovich equation,double constant rate equation and parabolic diffusion equation.【Results】Humic acid addition increased the content of the four heavy metals in the organic bound state in the soil by 0.78%-86.83% compared to CK. The leaching amount of all the four heavy metals were in large quantities when leached for 72 h. Then with the leaching time extended,and the release of heavy metals increased slowly. The cumulative release amount of the four heavy metals was in the order of：Cu>As>Zn>Pb. When 3% humic acid was added to the soil,Cu and As were significantly lower（P<0.05）than CK by 16.85% and 5.41%. The modified Elovich equation could simulate the release process of heavy metals Cu,As and Pb well. While the double constant rate equation could simulate the release process of heavy metal Zn well.【Conclusion】Humic acid addition could change the occurence form of heavy metals in the soil,reduce the leaching volume of heavy metals and lessen the risk of contamination when heavy metals were transported and transformed.

Key words: Soil, Humic acid, Tailings, Heavy metals, Release characteristics