保定市郊污灌区土壤重金属潜在生态风险评价

Assessment of Potential Ecological Risk of Soil Heavy Metals in Sewage Irrigated Area of Baoding Suburban

以保定市郊污灌区为研究对象,采用潜在生态风险指数法对污灌区土壤6种重金属元素进行单因子和复合生态风险评价。结果表明,污灌区11个采样点的Cd平均潜在风险系数为77.9,达到中度生态危害程度,其余元素均未达到轻度生态危害的上限标准,6种重金属平均潜在生态风险指数依次为Cd>Pb>Cu>Zn>Cr>Ni。在6种重金属元素中,Cd元素对生态风险的贡献率最高,是构成潜在生态风险的主要因子。另外,污灌区个别样点的土壤重金属综合生态风险指数为223.2,达到中度生态危害程度。与污灌区相比,对照区样点6种元素的单因子潜在生态风险系数均相对较轻,没有达到轻度危害程度,而且对照区4个样点的重金属复合生态风险指数相对于污灌区较轻,但存在Cd风险。

The ecological risks of soil heavy metals in the sewage irrigated area of Baoding suburban were discussed with the method of single and compound factor potential ecological risk index. The results showed that the soils had serious ecological risks of Cd with the single ecologi- cal risk index of six elements in sample points of irrigation area, the risk index was 77.9 , and slight risks of Cu, Zn , Cr, Ni and Pb with the index were loss than Cd. The risk order of heavy metals was Cd 〉 Pb 〉 Cn 〉 Zn 〉 Cr 〉 Ni. Among six metals, Cd was the main risk factor in the sewage irrigated area. Integrated ecological risk index of soil heavy metals of individual sample points in the sewage irrigated area was 223. 2, which indicated that the soil ecological risk of the area was moderate serious. By comparing the sewage irrigated area with the contrast area, the single potential ecological risk index of six soil heavy metals in contrast area was relatively lighter than that in sewage irrigated area, which didn＇t achieve minor harm. The integrated ecological risks of heavy metals, except for Cd, wer relatively light in the contrast area.