【摘要】 以湖南省某县稻田土壤样品为研究对象,分析Cd、Pb、Cr、As、Hg的污染特征及来源。利用单污染指数法、综合污染指数法、地累积指数法和潜在生态危害指数法评估稻田土壤的污染状况及生态风险,结合地统计信息绘图技术、条件推理树模型和主成分分析法研究湖南省某县稻田土壤中重金属的来源。结果表明:该县稻田土壤Cd、Pb、Cr、As、Hg的平均含量分别为0.729、49.9、79.2、19.8、0.244 mg·kg-1。综合污染指数大于3的重污染点位数占14.2%,轻污染及以上点位数占74.9%,说明该区域稻田土壤受到一定程度的重金属污染。综合潜在生态危害指数均值为84.9,总体处于轻微污染水平,其中Cd对综合潜在生态危害的贡献率为65.97%。结合空间差值研究发现高Cd分布区主要位于该县工业基地周边,结合条件推理树模型建立,发现该稻田中重金属Cd的来源主要与企业距离有关,此外,单位农田畜禽粪便承载量、距离工矿企业距离、反映投入品添加量的粮食均对Cd的污染具有贡献作用。结合主成分分析,Cd、Pb污染主要与工业污染源及交通运输有关,As、Hg污染主要与居民活动、生活及工业废弃物堆放及污灌有关,Cr主要与自然活动有关。湖南省该县重金属总体处于轻微污染水平,其中Cd是该农田生态风险的主要来源,Cd污染主要与工业污染源有关。更多还原

【Abstract】 The characteristics and sources of Cd, Pb, Cr, As, and Hg in paddy soil samples from a county in Hunan Province were analyzed.The pollution characteristics and ecological risk of paddy soils were evaluated using the single factor, comprehensive pollution, geoaccumulation, and potential ecological risk indices. The sources of heavy metals in paddy soils were analyzed using geostatistical information mapping techniques, conditional reasoning tree models, and principal component analysis. The average contents of Cd, Pb, Cr, As, and Hg in the paddy soils were 0.729, 49.9, 79.2, 19.8 mg·kg-1, and 0.244 mg·kg-1, respectively. A comprehensive pollution index exceeding 3 accounted for 14.2% of sites, while 74.9% of sites were mildly polluted and above sites, indicating that paddy soils in the studied county were contaminated. The average comprehensive potential ecological risk index was 84.9, indicating that the county is experiencing a mild pollution level. The contribution rate of Cd to the comprehensive potential ecological risk index was 65.97%, and it was the main source of ecological risk in the paddy soils. The Craig space difference found that high concentrations of Cd were mainly located in the industrial base of the county. The conditional reasoning tree model indicated that the Cd in the paddy soils was mainly related to the distance to the enterprises. In addition, the carrying capacity of livestock and poultry manure, distance to industrial and mining enterprises, and the amount of added grain were also related to the source of Cd. Combining with principal component analysis, it was found that Cd and Pb were mainly related to industrial pollution sources and transportation activities. Hg and As were mainly related to residential activities, residential and industrial waste stacking, and sewage irrigation, while Cr was mainly related to natural activities. The pollution level of heavy metals found in the paddy soil of this county in Hunan Province was mild, and Cd was the main source of ecological risk in the paddy soil. Cd pollution was mainly related to industrial pollution sources.更多还原