Distribution Characteristics of the Heavy Metal Cd in the Irrigation Water-Cultivated Soil-Fertilizer-Crop Ecosystem

Shuangqiao Countryside of Neijiang City in hilly ground area in the midland of Sichuan Province was chosen as the study geographic area to survey and analyze the content distribution characteristics of the Cd in the irrigation water, ground water mud, surface layer cultivated soil, profile soil and the fertilizer which were often used in the locality, and in different crops set earth, fructification as well. The results showed that the content of Cd in the irrigation and ground water mud respectively comply with the national agriculture use irrigation standard and the contamination control standard value in agriculture use mud (GB4284-84) respectively. The average contents in the surface cultivated soil and each layer of soil profile are all above the background level of Chengdu economic region (44%), referring a large scale pollution risk. The average value of Cd element in fertilizer was 1.81 μg/g, which was higher than the third class standard of national soil environment quality; The average content of Cd element in the crops’ set earth was 0.410-0.439 μg/g, which was higher than the second class standard of national soil environment quality and there was a measure of cumulation; The average values of Cd in crops’ fructificationwas all below the primary standard of national soil environment quality, and the bio-amplification coefficient sorting was CF(Cd peanut)> CF(Cd citrus)> CF(Cd rice)> CF(Cd corn). Irrigation water had little influence on the soil Cd pollution, where fertilizer using was closely related to the Cd pollution in the surface cultivated soil in the survey area and had a certain influence on the Cd cumulation in the crops. The sorption and enrichment of crops’ set earth and fructification was obviously different.