Study On Heavy Metals Pollution Of Soil And Cropper In Typical Area Of Xinjiang

With the rapid development of China’s economy, the industrialization and modernization of agriculture had brought immeasurable heavy metal pollution to soil. Pollution of heavy metals in soil would threaten human health through the food chain and in contact with human. This study was carried out in the middle of Northern slope of Tianshan Mountains in Xinjiang province, the aims of this study were: to determine total values of heavy metals in soil, to evaluate the pollution of heavy metals, to analyze the variability and spatial distribution of heavy metals and to grasp the contents and transfer rules of heavy metals in main crop. The main conclusions were as follows:The mean concentrations of Cu, Zn, Cd, Pb, As, Ni, Cr, Mn were 53.13 mg·kg-1, 105.66 mg·kg-1, 0.68 mg·kg-1, 22.01 mg·kg-1, 16.78 mg·kg-1, 37.21 mg·kg-1, 105.99 mg·kg-1, 913.91 mg·kg-1, respectively. The mean concentrations of heavy metals were higher than the background values in Xinjiang, and the concentration of Cd was even higher than the second criteria of Chinese environment quality. The coefficients of variation were from 18.50% to 72.29% by those heavy metals, they were ordered from high to low as follows: Pb > Cd > Ni > As > Cu > Zn > Mn > Cr. The results of soil physical and chemical properties showed that soil presented alkaline, drought, low fertility. The results of pollution index showed that the trend of heavy metals accumulation was obviously and the slight pollution level, moderate pollution level, heavy pollution level accounted for 12.44%, 15.56%, 72.00%, respectively. The results of EF showed that Cd fell into the moderate enr ichment group; other metals fell into the minor enr ichment group. The mean value of RI was 211.77, indicating high ecological risk, and Cd was the key factor for metal pollution in soil. The contents of heavy metals in different soil types showed that the highest contents of Ni and Cr were in mountain soil, other metals were in urban soil. Analysis of heavy metals contents in soil of different areas showed that the highest contents of Cd, Ni were in Kuitun and Dushanzi, respectively. And other metals in soil of Dushanzi were higher than other areas.The results of correlation analyses and PCA showed that, heavy metals showed significant correlation with each other, except for Cd and As, Pb and Ni. Cu, Zn, Pb, As, Cr, Mn were associated with the first principal component, Ni, Cd were distributed with the second, third principal component, respectively. The variability and distribution of spatial showed that, Cu, Cd, Pb showing moderate spatial correlation and other metals showing weak spatial correlation. The spatial distribution patterns of Cu, Zn, Pb, As were generally similar, with high values in the southeast and mid-east of the study area. Ni, Cr, Mn showed a generally similar pattern, with high values in the southwest and southeast of this study area. Cd displayed a different spatial distribution pattern from other metals, with high value in the southwest of this study area.The contents of heavy metals in crops showed that, the concentrations of Cu, Zn, Mn were higher than other metals in cotton and corn. The contents of metals in different parts were different, the higher content of metals were in leaf or stalk of cotton and root or leaf of corn. The leaf and stalk of cotton had the different transport capacity of heavy metals, the TF of Zn, Cd, As were higher in leaf and the TF of Cu, Pb, Ni were higher in stalk. The TF of As were higher in grain of corn, other metals had a higher TF in leaf of corn. The results of correlation analyses showed that, the correlations of heavy metals in each part of cotton were not consistent, only Cu and Ni showed signif icant correlation with each other in each part of cotton. The contents of heavy metals in soil had little effect on the concentration of metal in cotton. The results of BF showed that, the BFs of Cu, Ni, Cr in stalk were higher than other part of cotton, the BFs of Zn, Cd, Pb, As, Mn in leaf were higher than other part of cotton. The BFs of Cu, Zn, Cr, Mn in leaf were higher than other part of corn, the higher BFs of Cd, Pb, As, Ni were in root of corn.