沈抚污灌区农田土壤生态健康风险评价

本文以沈抚污灌区农田土壤中6种污染重金属Cd、Hg、As、Pb、Cu和Cr的实测含量作为基础数据进行研究,利用Hakanson潜在生态风险评价法与美国环保署(USEPA)推荐的健康风险评价法对污灌区农田土壤进行生态及健康风险评价。结果表明,该研究区域Cd、Hg、Pb、Cu、Cr含量均超过了辽宁土壤背景值,且有逐年上升的趋势,其中Hg和Cd污染较严重,超过了国家土壤环境二级标准;虽然土壤样品中90%多因子潜在生态风险处于中度危害水平,但是不同污灌方式对风险指数也有一定影响,以污灌至采样年地区风险值较高;单因子潜在风险中,以Cd和Hg危害程度较为严重,且也表现出由于污灌而使重金属浓度增加的趋势,土壤样品中分别有60%和100%生态风险指数处于较重危害水平以上。健康风险评价中,研究区域各点6种重金属HQ和HI值均小于1,理论上不存在非致癌健康风险;Cr、Cd和As的CR值和TCR值均超过了USEPA提出的土壤治理标准,存在较高的致癌风险。

Risk assessment of farmland soil ecological health in Shen-Fu sewage irrigation regions

Based on the concentrations of Cd, Hg, As, Pb, Cu and Cr in the farmland soil of Shen Fu sewage irrigation regions, soil ecological and health risks were evaluated with the Hakanson Potential Ecological Risk Index and the health risk assessment model recommend by the United States Environmental Protection Agency (USEPA) in this study. The results showed that the concentrations of Cd, Hg, Pb, Cu, Cr in this region were all higher than the soil background value in Liaoning Province, and showing an increasing trend year by year. Especially, Hg and Cd pollution was more serious, and the concentrations of them were over the grade Ⅱ national soil quality standard. Although the potential ecological risks of the 90% factors in soil samples were at a moderate risk level, different ways of sewage irrigation had some effects on the risk index, and the values of risk index in the area which had been sewage irrigated up to now were higher than the others. In the potential risk of single factor, the risks of Cd and Hg were more serious than other heavy metals, and it also showed that sewage irrigation would increase the heavy metal concentration in soil, and the ecological risk indexes of soil samples were 60% and 100% above the serious level respectively. In term of the evaluation of health risk, the HQ and HI values of six kinds of heavy metals in the regions were all lower than 1, which indicates that there is no non carcinogenic risk in this area theoretically. However, the CR and TCR values of Cr、Cd and As were all higher than the standard values of the US EPA, which mean that these heavy metals would have a high carcinogenic risk.