中文摘要：

选择海河流域典型清洁水系（滦河水系）为研究对象,全面分析表层沉积物中6种重金属的污染特征,并进行重金属的来源解析和生态风险评价.结果表明,整个水系表层沉积物中Cd、Cr、Cu、Ni、Pb和Zn的平均含量分别为0.31、104.53、34.47、29.03、34.92和86.47 mg·kg-1.除Ni外,其余5种重金属含量均不同程度超过区域背景值.重金属富集系数（EF）结果表明,Cd和Pb在滦河水系山区段部分样点存在明显的人为来源（EF=4.01和1.94）,可能是区域农业和林业施肥所致,Cr、Cu、Ni和Zn在整个水系均以自然来源为主（EF=0.88、1.28、0.75和0.88）.潜在生态危害指数（Eir）结果显示,6种重金属元素的危害指数大小顺序为：Cd〉Pb〉Cu〉Ni〉Cr〉Zn,其中,Cd属强生态危害水平（Eir=98.37）,其余5种元素均属轻度生态危害水平,而滦河水系表层沉积物中重金属污染整体仍处于轻度生态危害水平（RI=123.27）。

英文摘要：

The pollution characteristics,sources and risk of heavy metals in the surface sediments of Luan River System（ LRS）,a typical clean river of Haihe Basin were investigated. The results showed the mean concentrations of Cd,Cr,Cu,Ni,Pb and Zn in the sediment samples were 0. 31,104. 53,34. 47,29. 03,34. 92 and 86. 47 mg·kg- 1,respectively,and most of them were higher than the soil background values except Ni. Enrichment factor（ EF） values of these metals revealed that Cd and Pb in the mountain area of LRS（ EF = 4. 01 and 1. 94,respectively） were mainly from anthropogenic sources（ agriculture and forestry fertilization）,and Cr,Cu,Ni and Zn in the whole LRS were mainly from natural sources（ EF = 0. 88、1. 28、0. 75 and0. 88）. Potential ecological risk（ PER） indexes of individual elements（ Eir） and comprehensively（ RI） were calculated,and the orders of the average Eir for the studied metals were Cd〉 Pb 〉Cu 〉Ni〉 Cr 〉Zn. Although Cd posed high PER（ Eir= 98. 37）,the mean RI values showed low PER to the local ecosystem in the whole LSR（ RI = 123. 27）.