中文摘要：

分析了阳宗海柱状及表层沉积物中Al、Fe、Mn、Zn、Cr、Co、Ni、Cu、As、Cd、Pb等金属元素的含量,结合沉积年代学,研究了沉积物重金属污染的时空变化和潜在生态风险特征.结果表明,表层沉积物中重金属含量具有一定的空间差异性,As、Cd、Cu、Pb和Zn在中东部湖区含量较高,而Cr、Co、Ni含量高值位于南、北湖区的近岸区域;柱状沉积物中,1990s之前As、Cd、Cu、Pb和Zn含量较为稳定,1990s中后期以来,其含量逐渐增加,并在2009-2010年前后达到最大值,此后逐渐下降;而柱状沉积物中Cr、Co、Ni含量变化趋势与Al、Fe相似,总体上由下向上逐渐降低,这主要与沉积物质地（粒度）逐渐变粗有关.重金属富集系数表明,阳宗海沉积物中主要污染元素为As、Cd、Cu、Pb和Zn,1990s中后期污染程度快速增加,2009-2010年前后达到峰值,此后污染程度逐渐降低;表层沉积物中Cu为未污染至＂弱＂污染水平;Zn、Pb为＂弱-中等＂污染水平,As为＂中等-强＂污染水平,Cd为＂弱-强＂污染水平,中东部湖区污染程度高于其他湖区,这可能与该湖区缺少入湖径流、自然碎屑物质沉积速率较低以及砷污染事件等人为源的重金属贡献影响更为显著有关.生态风险评价结果表明,在2002-2010年前后沉积物重金属达到＂中等-强＂潜在生态危害,主要贡献因子是Cd和As,近年来其生态风险等级逐渐降低;表层沉积物中重金属在中东部湖区具有＂中等＂程度潜在生态危害,而其他湖区表层沉积物重金属具有较低程度的潜在生态风险.

英文摘要：

Contents of Al,Fe,Mn,Zn,Cr,Co,Ni,Cu,As,Cd and Pb in the surface and core sediments of Lake Yangzonghai were determined. Combined with geochronology,the heavy metal spatio-temporal characteristics,the status relative to the pre-industrial levels,and potential ecological risk of the pollution were evaluated by the surface and core sediments from Lake Yangzonghai. The results showed that metal contents exhibited obviously spatial variations in the surface sediments. Contents of As,Cd,Cu,Pb and Zn were generally higher in the middle-east lake area than those in other areas. In contrast,contents of Cr,Co and Ni showed higher values in the south lake area. Contents of As,Cd,Cu,Pb and Zn in the core sediment had increased gradually since the mid-1990 s and reached the maximum values around the year of 2009-2010,followed by a gradual decline in recent years. Contents of Cr,Co and Ni showed similar temporal variations to the trends of detrital metals（ such as Al and Fe）,and they decreased generally in recent hundred years. As,Cd,Cu,Pb and Zn in sediments of Lake Yangzonghai were contaminated as indicated by the enrichment coefficients,showing that metal contaminations began at the mid-1990 s and reached the maximum values around the year of 2009-2010,but it declined gradually in recent years with the implementation of industrial discharge control. In the surface sediments,Cu was at unpolluted to minimal contamination levels,while Zn and Pb displayed minimal to moderate contamination levels. Metal As had moderate to strong contamination levels,and Cd showed minimal to strong contamination levels.The pollution levels of the metals in the eastern lake were higher than those in other lake areas,these are because of a relatively rare runoff,low deposition of detrital materials and high anthropogenic/detrital metal sedimentation. The metals in sediment of Lake Yangzonghai may pose a medium to strong potential ecological risk when compared with a historical pollution peak around 2002-2010. The main contribution factors were