A Study On Leaching Simulated Experiments Of Elements In Soil Of The Kashin-Beck Districts In Aba Areas

Aba areas are the high incidence region of kashin-beck in our country, and ecological environment is very fragile. With the alternation of rainfall and freeze-thaw,the stability of reunion body in soil was damaged significantly.Rain eluviation may cause a large migration of most elements in soil especially nutrient elements, resulting the loss of elements in soil and the lack of the elements of the crops planting in the region, ultimately affect the human health.The dissertation is relying on the cooperation project between the government of Sichuan province and Ministry of Land Resources which the sub-name is "the survey of the ecological geochemistry in Aba Sichuan province (1212010913022)", and chooses the representative natural soisl of Aba areas as the research object. Simulating the elements migration in the soils with the natural rain by leaching experiment,to explore the influence factors of elements leaching migration in the soils of Aba kashin-beck region, and to analysis elements transfer characteristics. This leaching experiment includes two parts:statical leaching experiment and dynamical leaching experiment. To examine the relation between elements concentration in the liquid and leaching time, also besides the relation with different pH values, and to explore the connection between elements leaching and the cause of KBD.The research results show that:(1) The main mineral composition in soil samples of Aba, Rangtang, Hongyuan regions is quartz, feldspar, montmorillonite, and the soil in Aba region also contain a small amount of calcite and kaolinite. In general, mineral composition does not have much difference. The content of soil samples has certain differences. Overall, the content of soil samples in Rangtang region is relatively higher, and the content of soil samples in Aba region is relatively lower.(2) The features of elements concentration in the liquid have three types in dynamical leaching experiment:the one is the elements concentration reduced gradually over time, such as Cr, Cu, Se, K; the other is the elements concentration increases firstly and then decreases, such as Ba, Mg, Sr, Ca; the third is elements concentration have a little change, such as Pb, Ti.(3) The elements leaching strength of Se、Ca、Mg、Sr are more higher, and the elements leaching strength of Mn, Pb, Zn, Al, Fe are relatively lower. From a regional view, the leaching strength of elements in the liquid of Hongyuan region is the highest, and the leaching strength of elements in the liquid of Aba region is the lowest. In general, the leaching strength of trace elements reduced gradually over time, and the leaching strength of elements increases firstly and then decreases. Under the conditions of weak acid, the elements leaching strength are the highest.(4) The elements migration coefficient of K, Ca, Mg are more higher, with strong ability of migration.The highest migration coefficient is1.009, and its quantity of leaching is more than50%. While the elements migration coefficients of Ti, Pb are more lower. From a regional view, the ability of elements migration in soil of Hongyuan region is the strongest, and the ability of elements migration in soil of Aba region is the weakest. Under the conditions of weak acid and weak alkali, the ability of elements migration in the filtrate fluid is higher than the neutral’s.(5) According to the annual rainfall of soil sample collection region, theoretically obtain annual leaching rate of three regions. Compared the results, the elements leaching in soil of Se, Ca, Mg are intense. While these elements are important in the body’s metabolism activities, especially in joint and bone tissue metabolism the elements have very important function.The cause of kashin-beck disease may have some relationship with the elements leaching in soil.