Comprehensive evaluation of potential ecological risk of heavy metals in the surface soil of the farmland in wastewater irrigation area of southern suburbs in Baotou | 包头南郊污灌区农田表层土壤重金属潜在生态风险综合评价

chinois. 评价包头市南郊污灌区农田土壤Pb、Cr、Cu、Zn、Ni 5种重金属元素的潜在生态风险，为污灌区土壤环境质量评价、土壤重金属污染修复提供科学依据。在包头市南郊四道沙河流域的麻池乡城梁村，选取有代表性的8个采样点，按照“梅花形”布点取样采取农田表层0~20 cm土样，测定土壤重金属Pb、Cr、Cu、Zn、Ni元素含量，并采用单因子污染指数法、内梅罗综合污染指数法和Hakanson潜在生态风险指数法，对研究区土壤重金属的潜在生态风险进行评价。包头市南郊污灌区农田土壤中的5种重金属元素含量还不到污染级，但除Cu含量基本接近河套地区土壤背景值外，其他4种重金属元素含量的平均值均超过了当地土壤背景值，其中以Cr、Ni元素含量的平均值超过地区背景值最高，且具有明显高度富集的特征。各种重金属污染的潜在生态风险指数由强至弱依次为Ni（49.59）＞Pb（41.18）＞Cu（39.70）＞Cr（23.24）＞Zn（8.62），其中Ni的潜在污染风险指数最高，是主要潜在生态风险因子，其次是Pb。人类活动导致包头南郊污灌区农田土壤中Pb、Cr、Cu、Zn、Ni　5种重金属元素明显积累，且已表现出一定程度的潜在生态风险，应该引起足够的重视。

anglais. The research aimed to evaluate the potential ecological risk of heavy metals Pb, Cr, Cu, Zn, Ni(HMPN) in the surface soil of the farmland in wastewater irrigation area of Baotou’s Southern suburbs(SFWB) to provide a scientific basis to the evaluation of soil environmental quality and repair of heavy metal pollution in sewage irrigated area. Eight representative sampling points in Chengliang village of Machi township in Sidaoshahe basin of Baotou's Southern suburbs were selected. Samples with 0-20 cm in the surface soil of the farmland were collected by using quincunx distribution to determine the content of HMPN, and Single-factor pollution index, Nemerow pollution comprehensive index and Hakanson pollution index of potential ecological risk method were employed to evaluate the potential ecological risk of heavy metals in 0-20 cm deapth farm soil of the study area. The results indicated that the environmental quality of HMPN in the SFWB was lower than pollution levels. Then the average content of Pb, Cr, Zn, Ni was greater than the regional background values except that the content of Cu was close to the regional background value of soil in Hetao region, and average content of Cr, Ni was the highest and much more than regional background value with the characteristics of highly enriched. The potential ecological risk indexes of variety heavy metal pollution was Ni(49.59)＞Pb(41.18)＞Cu(39.70)＞Cr(23.2)＞Zn(8.62), Ni was the main potential ecological risk factor and followed by Pb. HMPN was obviously accumulated in the SFWB as human activities. Attention should be paid to heavy metals pollution with potential ecological risk to a certain extent.