A study on distribution of elements of soil in Nanbu County, Sichuan Province

Basing on geochemical survey data of land quality in Chengdu-Chongqing area, this paper discusses distributions and geochemical backgrounds of 54 elements of soil in Nanbu County, Sichuan Province.Compared with elements backgrounds of soil in China,the contents of heavy metal elements of As、Cu、Hg、Pb、Zn are lower, while Cd, Cr are higher and Ni is equivalent. Compared with the layer A soil in China, the backgrounds of most heavy metal elements and plant nutrient elements are lower,while 10 elements such as CaO, Cd, MgO, Cr, F are with a higher background. Except heavy metal elements,element backgrounds of soil of most other elements in Nanbu County are equal to those in China, indicating that the effect of epigenetic and human activity on the surface soil is slight.The elements of C, CaO, Cd, Organic C, I, MgO, N, P, S, Se are concentrated in the surface soil, suggesting that these elements are concentrated by their geochemical behaviors and human activity inputs. The element distributions in surface soil of the Quaternary and the Jurassic Suining Formation are quite different, and the concentration or dilution characteristics are obvious.As far as the pH value ranges are concerned, with regard to the range of Ph values,contentsof Cd, F, Cl, Mn, N, P, K₂O, S, CaO, C, organic C are higher in alkaline environment, while contents of As, Cr, Cu, Ni, Pb, Zn, Co, B, Mo, Ge, TFe₂O₃ and SiO₂ are higher in acidic environment, and most elements tend to be stable in neutral environment.