| Farmland environment is the base for agricultural productions. It will affect directly on the quality of agricultural products. Farmland soil is an important aspect of farmland environment. Along with the global economic developments, the pollution of farmland soil from industrials is gaining more and more attention during recent years. The pouring of various chemical industrial parks'wastewater, gas and offscum are obviously affecting the farmland soil-crops system. In this study, different industrial parks of herbicide, fungicide and pesticide were investigated. Extensive soil and crops samples (rice and wheat) were collected from large areas around these industrial parks. We analyzed the effective status and amount of heavy metals, pH value of soils, the organic substances in soils and the amounts of Cd, Cr, Cu, Ni, Pb, Zn, Hg and As in crops. Then the effects of different types of industrial parks on heavy metals'characteristics, distributions and their relations were specified. This study will provide scientific and practical means for management and utilization of soils around industrial parks, and for product arrangement and safety. Results indicated:1. The distribution characteristics of heavy metals in soils around different types of Industrial Parks and pollution sources analysisCompared to the the natural background values of Jiangsu Province:In the farmland soil around a herbicide industrial park, the average contents of Hg, Cu, Cd and Pb were higher, and the contents of Hg and Cu were the highest; In the farmland soil around a fungicide industrial park, average contents of Zn, Cu, Pb and Cd were higher than the background values and Zn and Cu were the highest; In the farmland soil around a pesticide industrial park, the mean contents of heavy metals Cd, Hg, Cu and Pb exceeded the natural background values and Cd and Cu were the highest. Compared to the national standard II, in the soil around a herbicide industrial park, the average pollution exponent values of Cd, Cr, Cu, Ni, Pb, Zn and As were all below one, but the values of Hg and Cu were 1.59 and 1.05 respectively; In the farmland soil around a fungicide industrial park, the average contents of heavy metals in soils were under one. However, contents of some heavy metals, except Cr, As and Ni, went beyond the standard, and the exceeding percentage was between 9.91% and 18.95%; In the soil around a pesticide industrial park, the mean value of single factor pollution index of all soil samples was less than one with the exception of Cd and Hg. Cd is a dominant element causing heavy metal pollutions in the area. The spatial distribution of heavy metals around different types of industrial parks were as follows:The pollution exponents of soils were largest between 200m and 1400m around these three types of industrial parks, and exhibiting obvious directional characteristics along southeast and northwest directions. It is quite related to the main direction of wind in Jiangsu Province. The sources of heavy metals in soils around different types of industrial parks:Based on the Principal Component analysis and Correlation analysis, Zn, Ni, Cr, Pb and As were mainly from soil parent materials, and Hg, Cu, and Cd were mainly related to human activities for herbicide industrial parks; Zn, Ni, Cr, Pb and As were mainly from soil parent materials, and Hg, Cu, and Cd were mainly related to human activities for fungicide industrial park; Cd, Hg, Ni, Cr and As were mainly affected by soil parent material, while Zn, Cu, and Pb were mainly affected by human activities for pesticide industrial park.2. Different types of Industrial Parks have obviously different effects on the contents distributions of heavy metals in soil. Compared with the limits of pollutions of national food standard, the average amount of seven heavy metals of rice and wheat around three industrial parks does not exceed the standard and the crops are generally clean. However, the largest values of some heavy metals in rice and wheat around the three industrial parks are larger than the standard. Compared to soil heavy metals, the crops heavy metals are very similar, but larger than the comparison areas. These results indicated that the crops around industrial parks had been polluted differently by the heavy metals in industrial parks. The spatial distributions of heavy metals in the crops around different industrial parks were as follows:The heavy metals contents around three different industrial parks were largest along southeast and northwest directions. Being further from industrial parks, heavy metal amounts along different directions increased first, then decreased, and became stable at last. This was in accordance with the trend of heavy metals in soils. At the same distance from industrial parks, the heavy metal amounts in rice and wheat along different directions were different, which indicated that heavy metals may also affected by the soil character, pH value, and organic substance, etc.3. From the analysis of the heavy metals'effective status, amount in soils and crops around different industrial parks, we concluded that there was an obvious relativity between heavy metals'effective status in crops and in soils. And there were also relativities of heavy metals'amount, soil pH value and organic substance amounts between soil and crops. The amount and distribution of heavy metals in soils and crops around different industrial parks were affected by several factors, such as industrial park pollution, soil character, crops and heavy metals species. In terms of different heavy metals, the absorption abilities of Cu and Zn by wheat were stronger than by rice. However, the absorption ability of rice became stronger when came into Pb, Cd and Hg. In terms of different crops, the absorption ability of wheat towards different heavy metals was in the order of:Cu>Zn>Hg>Cd>Pb. For rice, the order was:Hg>Cu>Cd>Zn>Pb. As a result, for different types of industrial parks, we should plant different crops according to the pollution characteristics. At the same time, monitoring the contents of main metals in different crops can effectively prevent the heavy metal pollutions in soils and crops, thus to prevent harming people's health. |
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