杞麓湖径流区不同湿地沉积物重金属污染特征及潜在生态风险评价

为了解杞麓湖农业径流区低污染水所致湖滨带湿地重金属空间分异特征及潜在危害，采集湖滨带农业径流区32个不同类型湿地（河流湿地n=13、人工湿地n=10、湖泊湿地n=9）的表层沉积物，检测重金属Cu、Zn、Pb、Cr、Cd、Ni和Hg含量，利用ArcGIS反距离权重插值法（IDW）分析7种重金属空间分布特征，采用Hakanson潜在生态风险指数法评价杞麓湖农业径流区湿地重金属污染。结果表明：不同类型湿地7种重金属污染程度存在差异，平均含量由高到低依次为河流湿地 > 人工湿地 > 湖泊湿地，各重金属平均含量由大到小依次为Zn > Cr > Cu > Ni > Pb > Cd > Hg，除Pb外，其余6种重金属平均含量均超过云南省土壤背景值，Cd超背景值样点比例高达100%。单因子污染指数表明重金属Cd和Hg呈重度污染，存在危害风险；农业径流区潜在生态风险指数介于112~1 241，平均264，属中度风险水平；重金属含量分布存在明显空间差异，北部高于南部、西部高于东部，含量分布高值区与潜在生态风险评价结果一致。相关性分析表明Cu、Ni、Cr和Zn污染源主要是农业活动；Pb来源主要与道路交通有关，还受工业活动影响；Cd主要受农业活动和工业活动影响。研究表明，杞麓湖农业径流区不同类型湿地重金属污染存在空间差异，Cd和Hg污染严重，生态风险高值区出现在西北部和西南部。

Spatial differentiation characteristics and environmental risk assessment of heavy metals in wetland sediment in an agricultural runoff area in the Qilu Lake basin

To understand the spatial differentiation characteristics and potential hazards of heavy metals in lakeside wetlands caused by low-pollution water in the agricultural runoff area of Qilu Lake, the surface sediments of 32 different types of wetlands(river wetlands n=13, constructed wetlands n=10, and lake wetlands n=9) in the lakeside agricultural runoff area were collected to detect the contents of the heavy metals Cu, Zn, Pb, Cr, Cd, Ni, and Hg. The spatial distribution characteristics of the seven heavy metals were analyzed by inverse distance weighted interpolation in ArcGIS, and the Hakanson potential ecological risk index method was used to evaluate the risks of heavy metal pollution in the Qilu Lake agricultural runoff area. The results showed that the degree of pollution of the seven heavy metals in different types of wetlands was different, and the average content was in the order of river wetlands > constructed wetlands > lake wetlands. The average content of heavy metals was in the order of Zn > Cr > Cu > Ni > Pb > Cd > Hg. Except for Pb, the heavy metals exceeded the background value of Yunnan soil, and the proportion of Cd samples exceeding backgroung value was as high as 100%. The risk index of the agricultural runoff area ranged from 112 to 1 241, with an average of 264, which indicated a moderate risk level. There were clear differences in the distribution of heavy metals, which was higher in the north than in the south and higher in the west than in the east. The areas with a high distribution were consistent with the results of the potential ecological risk assessment. The correlation analysis showed that the sources of Cu, Ni, Cr, and Zn pollution were mainly agricultural activities; the sources of Pb pollution were mainly related to road traffic, but were also affected by industrial activities; and the sources of Cd pollution were mainly agricultural activities and industrial activities. There were spatial differences in heavy metal pollution among the different types of wetlands in the Qilu Lake agricultural runoff area, among which Cd and Hg pollution were serious. High ecological risk areas appeared in the northwest and southwest, which should be given more attention.