广西重金属高背景地区石漠化程度对 土壤汞形态及迁移特征影响.

Rocky resertification in Guangxi is widely distributed and becomes one of the serious ecological problems. The Hg pollution in some rocky desertification areas is more prominent. In order to understand the influence of rocky desertification degree on speciation and mobility of heavy metal mercury, different rocky desertification soils(potential rocky desertification, light rocky desertification, medium rocky desertification and severe rocky desertification) with high mercury background value were collected in Huanjiang of Guangxi. The mercury speciation was analyzed by three-step continuous extraction method recommended by Environmental Protection Agency(The mercury was divided into moving dynamic, semi-dynamic and non-moving dynamics). The relationship between mercury content and soil properties of different components in soil, and the mobility and transformation law of mercury in soils of different rocky desertification grades were discussed. The results showed that the content of mercury in high background rocky desertification soil ranged from 0. 3 to 4. 5 mg/ kg, with an average of 3. 46 mg/ kg. The main form of mercury was half migration, accounting to 69%-80% of the total mercury content, with an average of 75. 3%. The pH, cation exchange capacity, organic matter and mobile mercury were negatively correlated, while the total iron, total manganese, total aluminum, free iron oxide and free manganese oxide were positively correlated. The degree of rocky desertification promoted the increase of total mercury concentration, but also promoted the transformation of soil mercury form to mobile mercury, and the mobility of soil mercury. [ABSTRACT FROM AUTHOR]