Heavy Metal Pollution Characteristics In The Manasi River Basins

Urban industrial activities in the growing accumulation of heavy metals in terrestrial environments,and these heavy metals via dust inhalation, skin contact, etc. directly into the human body, but also through ingestion of contaminated animals and plants in the environment indirectly enter the human body. Seriously affecting heavy metal contamination on soil quality caused has become an important issue of security and agriculture healthy and sustainable development of agricultural products face.Object: This study of Manas River Basin cities and farmland topsoil As, Cd, Cr, Cu, Mn, Ni, Pb, Zn and other eight kinds of heavy metal content in the investigation, analysis of soil heavy metals study area the spatial distribution of heavy metals in soil and environmental quality and potential ecological risk assessment is intended to provide basic data and scientific basis for soil quality construction and sustainable agricultural development in the study area.In Manas, Shihezi City, Shawan eastern region of the study area, using a grid soil samples were collected from cities and farmland 129 by microwave digestion- Plasma- Atomic Emission Spectrometry(ICP) measurement of soil As, Cd, cr, Cu, Mn, Ni, Pb, Zn total of eight kinds of heavy metals content.Application of statistical methods to the analysis of heavy metals in farmland soils in the study area spatial distribution of single factor pollution index, Nemerow comprehensive pollution index of heavy metals in the soil environmental quality and potential ecological risk assessment using hierarchical cluster analysis of heavy metals in the soil the spatial differentiation, the use of self-organizing map neural network(self-organization map, SOM) of eight kinds of heavy metals were heterosexual spatial analysis, evaluation and monitoring site optimization and adjustment on this basis. The conclusions are as follow:(1) Manas River Basin cities and farmland topsoil heavy metals As, the mean Cd, Cr, Cu, Mn, Ni, Pb and Zn were 4.342, 0.115, 96.882, 44.710, 750.235, 24.058, 8.427, 97.007 mg · kg- 1, lower than the national standard of the soil, but the average Cd, Cr, Cu, Zn exceeds the background value Xinjiang.Wherein accumulation of Cd and Zn more serious. Eight kinds of heavy metal content in the range of variation coefficient of 16% to 164%, are moderate variability, including As, Cd dispersion coefficient greater than 1, indicating that the two metal ions regional heterogeneities larger.(2) It has a very significant correlation between strong homology As and Cd, Cu, Pb, organic matter content; Cr and As, Cd shows a negative correlation showed significant heterologous features; soil pH and metals relevant, but no significant correlation relationship, but negatively correlated with soil organic matter, indicating that soil organic matter content increased as the pH decreased.(3) Manas River Basin cities and farmland topsoil eight kinds of heavy metal content higher degree of accumulation areas are mainly distributed in Shihezi City, Industrial Zone, northwest of Manas and Shawan County east. As culminated in the north industrial area in Shihezi City, Cd, Cu, Mn, Zn highest value in Shihezi City, the surrounding farms; Cr and Pb highest values ??appear in Shihezi downtown, Ni highest value in Manas.(4) Manas River Basin cities and farmland topsoil eight kinds of heavy metals in the single factorpollution index order of PCr > PCu > PZn > PMn > PCd > PNi > PPb > PAs, As, Pb, Cd in a clean state, Cr mild between pollution and moderate pollution; Cu, Mn, Ni, Zn are mild pollution; Nemerow pollution index evaluation showed that 81% of light pollution in the area, 11% moderately polluted areas, 8% of the weight of the region Pollution.(5) Multiple hierarchical clustering analysis of visual distinction between the heavily polluted area and safe area, the order of the degree of pollution industrial area> City> farmland> Mountain,self-organizing map neural network showed samples of Shihezi City, North Industrial Zone the most obvious characteristic of pollution, according to a representative of the opposite sex spatial distribution of the intensity and spatial uniformity, the proposed deletion of 43 sampling points as a result of optimization.(6) The cumulative trend of 8 kind of heavy metals in cotton and corn plant were observably, the content of Cr, Cu, Mn and Zn in all parts of the two plants were high, except the corn seed. However, corn and cotton were different in metal transfer coefficient and cumulative ability, cotton plants showed great gathering ability on metals, especially on Pb; corn showed great gathering ability on Mn, while the ability were weak on other seven metals.