阳宗海湖滨湿地沉积物中重金属空间分布特征

以阳宗海不同湖岸湖滨湿地沉积物为研究对象，分析测定沉积物中7种重金属含量，评价不同湖岸重金属的污染程度，探讨在不同干扰方式下湖滨湿地沉积物中重金属的主要污染特征，为阳宗海重金属污染防治提供理论依据。结果表明：（1）阳宗海湖滨湿地不同湖岸7种重金属元素污染程度存在差异，表现为：东岸>北岸>南岸>西岸。As、Cd、Cr、Zn、Mn的最高值出现在东岸，Co、Cu、Ni的最高值出现在北岸，Pb的最高值出现在南岸。（2）不同区域湿地沉积物中，东岸（Cu、Ni、As、Cd）、南岸（Cu、Cd）、西岸（Cd）、北岸（Cu、Ni、Cd）的重金属含量明显高于土壤环境质量2级标准，是主要的重金属污染因子，Cu、Ni、As、Cd的含量分别为43.41~111.15、41.64~57.23、10.28~65.31、1.02~1.99 mg/kg；（3）阳宗海流域上游的铝厂、电厂等高污染企业产生的工业“三废”未经有效净化直接排放，流域周围生活污水、化肥和农药等农业面源污染是导致湖泊重金属污染严重的主要原因；（4）湖滨湿地沉积物中重金属与有机质、全磷之间相互影响，Cu、Ni、As和Cd与全磷呈显著正相关，相关系数分别为0.674、0.790、0.357和0.626（P<0.01），增加磷的含量，会增加沉积物对重金属的吸附量；Cu、Ni、As和Cd与有机质呈显著正相关，相关系数分别为0.393、0.451、0.406和0.497（P<0.01）。有机质的降解促进金属离子的释放，使沉积物中重金属含量增高。

Spatial Distribution of Heavy Metals in the Sediments of Yangzonghai Lake Wetland

Heavy metals in the sediments of lakeside wetlands threaten aquatic plants and animals, especially those that bioaccumulate. Yangzonghai Lake is a plateau lake located at the intersection of Chengjiang, Chenggong and Yiliang Counties in Yunnan Province. In this study, we investigated the concentration of seven heavy metals in the sediment of Yangzonghai Lake wetland and their spatial distribution and behavior under different types of human disturbance were characterized. In August 2015, sampling transects were established in the eastern, southern, western and northern areas of the Yangzonghai Lake wetland with three sampling sites per transect. Samples of surface sediment (0-10cm) were analyzed for As, Zn, Cu, Cr, Cd, Ni and Pb. Results show that: (1) Concentrations of the seven heavy metals exhibited remarkable spatial variation in the wetland sediments and the order of total contamination by transect was as follows: east > north > south > west. The highest concentrations of As, Cd, Cr, Zn and Mn were found in the eastern area, but the highest concentrations of Co, Cu and Ni were in the northern area and the highest Pb concentration was in the southern area; (2) The concentration ranges for Cu, Ni, As and Cd were, respectively, 43.41-111.15 mg/kg, 41.64-57.23 mg/kg, 10.28-65.31 mg/kg and 1.02-1.99 mg/kg, all exceeding the secondary standard for soil environmental quality, and they are the primary heavy metal pollutants in the Yangzonghai Lake wetland; (3) The heavy metal pollution in Yangzonghai Lake was attributed primarily to upstream industrial wastewater discharges from high pollution enterprises such as aluminum smelters and power plants, with smaller contributions from agricultural non-point source pollution; (4) Heavy metals, organic matter and total phosphorus interact in the wetland sediments. There was a significant positive correlation of Cu, Ni, As and Cd concentrations with total phosphorus, with correlation coefficients of 0.674, 0.790, 0.357 and 0.626 (P<0.01), respectively. The concentrations of Cu, Ni, As and Cd were also significantly positively correlated with organic matter, with correlation coefficients, respectively, of 0.393, 0.451, 0.406 and 0.497 (P<0.01). The degradation of organic matter promotes the release of metal ions and increases the heavy metal content of sediments. These results provide a theoretical basis for controlling heavy metal pollution in Yangzonghai Lake.