A Preliminary Study On Soil Heavy Metal Pollution And Phytoremediation Technology In Agricultural Soils In Chang-Zhu-Tan Area

Xiangjiang river basin of the ChangZhuTan regional soil types and the condition of heavy metal contamination in soil and the distribution of the pollution were studied by on-the-spot investigation, sample collection and data analysis. At the same time, the risk of pollution caused by heavy metals in soil which are listed by the Ministry of Environmental Protection’s "Twelfth five plan" was evaluated. The assessment of soil environmental quality and the classification of regional risk were carried out on typical heavy metal pollution area which was chose on the basis of studying of heavy metals in soil of metal mining and smelting areas of the ChangZhuTan area. The assessment method of the risk of soil heavy metal in the ChangZhuTan metal mining district was estabished and the basis was provided for establishing the system of index of emergency risk evaluation of different heavy metals and different types of activities of mining and metallurgy emergencies. And technical reference for the dealing with heavy metal pollution in the ChangZhuTan area was provided for the phytoremediation on the typical farmland soil and the screening of high accumulation rice. The main findings were as follows:Surrounding Zhuzhou Smelter farmland soils:the study area of soil was not the same point in Pb, Zn, Cr concentration in spatial, and the difference was relatively large, there appeared obvious features in outside sources of pollution in the form of heavy metals into the soil environment; Relationships between the average concentration of heavy metals were from high to low was as belows:Cu, Zn, Cr concentration decreased from upland to paddy; Pb, Hg, As concentration decreased from upland to paddy; Cd concentration have gradually decreased from paddy to dry land. Surrounding areas, the level of dry lands Cd contamination was a heavy pollution, almost seriously; the contamination of Zn pollution was moderate in soil, crops; the levels of Cr, Cu, Ni, Pb pollution were slightly polluted, over the background level, the crops value began to be contaminated; Zhuzhou Smelter plays a major responsibility for Chang-Zhu-Tan area in soil heavy metals pollution.The average of the total amount of heavy metals of Cd in Xiangtan Restoration Base exceeded the national secondary standards, in Cu, Zn, Pb, none exceeded the national standard; The total amount of heavy metals of Zn was in the maximum coefficient of variation (33%), the largest variation of available heavy metals was Zn (10%); Cd, Cu, Zn, Pb concentration was positively correlated with total and available heavy metal concentration in soil in Xiangtan Restoration Base; The average pollution levels of heavy metals in the soil in Xiangtan Restoration Base was low, and the surrounding farmland Gufeng was in moderate pollution level, Feilong and Xiangtan Restoration Base were slightly polluted, the pollution levels were not more than the third standard; The single pollution index order of Gufeng was as follows:Cd> Cu> Zn> Pb. The single pollution index order of Feilong and Xiangtan Restoration Base was as follows:Cd> Zn> Cu> Pb; According to the potential ecological risk (Ei), Cd concentration of soil was the highest in those sampling points, those have all reached a moderate ecological hazards, Pb, Cu, Zn showed slight ecological hazards, the minimum coefficient of ecological hazard was Zn, and it was also the minimum degree of harm;7.8%brown rice Cd concentrations were safe range;21.6%Cd concentration in brown rice, you need to attract attention;70.6%brown rice was in potential health hazards of Cd.The most obvious regularity was the concentrations of heavy metals Cd in Four varieties of rice chaff, the difference in different trials in the four varieties was significant, and the difference between Miyang23and IR8which was not so significant.In the two trials in Feilong and Gufeng, the maximum Cd concentration of the rice chaff were the varieties of A159, the minimum concentration were the varieties of A16; Comparing different varieties of rice chaff in Xiangtan Restoration Base in2013, Cd concentration of chaff was as follows:IR8> Miyang23.According to the coefficient of bioaccumulation of heavy metals, the coefficient of Cd accumulation of brown rice, straw, chaff in Feilong were in the order of:A159>Miyang23>IR8> A16. The coefficient of Cd accumulation of brown rice, straw, chaff in Gufeng were in the order of: A159> Miyang23>IR8> A16.Comparison of different parts of different, the enrichment coefficient of Cd in A16in Longfei and Gufeng Villages are:straw> husk> Brow, and straw> rice> chaff respectively; the enrichment coefficient of Cd in A159in Longfei and Gufeng Villages are:straw> rice> chaff, and straw> husk> brown respectively; the enrichment coefficient of Cd in Miyang23in Longfei and Gufeng Villages are:straw> husk> brown, and straw> rice> chaff respectively; the enrichment coefficient of Cd in IR8in Longfei and Gufeng Villages are:straw> husk> brown, and straw> rice> chaff, respectively.From the Bio-transfer coefficient, it can be deduced that the transfer coefficient ratio of rice is lower than the ratio of straw; In addition to transfer coefficient of brown rice in A16was higher than straw, and the remaining three transfer coefficient of brown rice were lower than straw.