江汉-洞庭交界水网平原区耕地土壤重金属污染风险评价与累积预测

Risk assessment and accumulation prediction of heavy metal pollution in arable soils of the Jianghan-Dongting interconnected river-lake plain

  • 摘要: 耕地土壤环境污染主要表现为重金属污染.文章以Cd、Hg、As、Pb、Cr、Cu、Ni、Zn为评价因子,运用土壤环境容量理论对区域性耕地土壤重金属环境进行污染风险评价.通过核算区域内由大气沉降、化肥施用、灌溉用水和畜禽粪便还田和配合饲料投放输入的重金属量,运用动态环境容量累积规律进行累积预测.结果表明:研究区耕地土壤重金属复合污染环境风险低,环境容量较充足,除少数点位处于中高环境风险外,整体环境相对安全.单项重金属方面,As、Cd污染风险最大,部分点位存在环境污染,Hg、Pb、Cu、Zn 风险整体可控,仅少数点位处于中高风险,Cr和Ni元素风险等级最低,均为无风险或低风险.研究区耕地土壤重金属年输入量Cd 3.12 g·hm−2、Hg 0.56 g·hm−2、As 66.33 g·hm−2、Pb 254.76 g·hm−2、Cr 53.23 g·hm−2、Cu 134.17g·hm−2、Ni 31.81 g·hm−2、Zn 524.14 g·hm−2.未来5、10、20、30、50 a和100 a内,各项重金属累积量低于风险基准值,整体风险较低.As、Cd未来5、10、20、30、50和100 a内累积空间分布结果表明,随着年限增加,As、Cd累积性污染风险呈逐渐加剧趋势,大气沉降、灌溉用水、畜禽粪便还田和配合饲料投放是主要输入途径.

     

    Abstract: The soil environmental pollution of cultivated land is mainly manifested as heavy metal pollution. In this paper, Cd, Hg, As, Pb, Cr, Cu, Ni and Zn were used as evaluation factors, and the soil environmental capacity theory was used to evaluate the pollution risk of heavy metals in regional cultivated soil. By calculating the amount of heavy metals input by atmospheric deposition, chemical fertilizer application, irrigation water, livestock and poultry manure returning to the field and compound feed in the region, the accumulation prediction was carried out by using the accumulation law of dynamic environmental capacity. The results showed that the environmental risk of heavy metal compound pollution in cultivated soil in the study area was low, and the environmental capacity was sufficient. Except for a few points in the middle and high environmental risk, the overall environment was relatively safe. In terms of individual heavy metals, As and Cd have the greatest risk of pollution, and some points have environmental pollution. The risks of Hg, Pb, Cu and Zn are generally controllable, and only a few points are at medium and high risks. The risk levels of Cr and Ni are the lowest, all of which are risk-free or low risk. The annual input of heavy metals in cultivated soil in the study area was Cd 3.12g·hm−2 Hg 0.56g·hm−2, As 66.33g·hm−2, Pb 254.76g·hm−2, Cr 53.23g·hm−2, Cu 134.17g·hm−2, Ni 31.81g·hm−2, and Zn 524.14g·hm−2. In the next 5, 10, 20, 30, 5 a and 100 a, the accumulation of heavy metals is lower than the risk base value, and the overall risk is low. The results of the cumulative spatial distribution of As and Cd in the next 5, 10, 20, 30, 50 and 100 years showed that the cumulative pollution risk of As and Cd gradually increased with the increase of years, and atmospheric deposition, irrigation water, livestock and poultry manure returning and compound feed were the main input channels.

     

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