丹江口水库表层沉积物重金属污染特征及风险评价

Pollution Characteristics and Evaluation of Heavy Metals in Surface Sediments of Danjiangkou Reservoir

丹江口水库是南水北调中线工程的重要水源地,为系统了解其库区沉积物中重金属污染现状及潜在的环境风险,采集了丹江口水库22个样点的表层沉积物,分析其中钒(V)、铬(Cr)、锰(Mn)、镍(Ni)、铜(Cu)、锌(Zn)、砷(As)、铷(Rb)、锶(Sr)、钡(Ba)、铅(Pb)等11种重金属元素的空间分布特征及来源,评估各重金属元素的潜在环境危害性。结果表明:沉积物中的重金属含量在空间分布上呈现“丹江库区>汉江库区>河道”的特征;重金属元素富集程度表现为Ba>Sr>Zn>V>Mn>Cu>Pb>As>Cr,而Ni和Rb无明显富集;Cr,As,V和Ni可能来源于天然的地球化学过程,而Zn,Mn,Sr,Cu,Ba,Rb和Pb则受冶金为主的工业影响较大。地累积指数法显示风险主要来源于干流入库、临城区岸带以及丹江库区中心等区域的沉积物中部分重金属元素如Cu,Zn和Sr等导致丹江口水库沉积物的重金属环境风险较低,整体状况较好。

Danjiangkou Reservoir is an important water source for the Middle Route of the South-to-North Water Diversion Project.In order to systematically understand the current status of heavy metal pollution and the potential environmental risks in the reservoir area,this study sampled the surface sediments of 22 locations in Danjiangkou Reservoir.The concentrations of 11 different heavy metal elements:vanadium(V),chromium(Cr),manganese(Mn),nickel(Ni),copper(Cu),zinc(Zn),arsenic(As),rubidium(Rb),strontium(Sr),barium(Ba),and lead(Pb)were examined,and the spatial distributions and origins of heavy metals were analyzed.The cumulative index method and potential risk index method were used to evaluate the potential environmental risks of each heavy metal.The overall heavy metal concentrations in sediments show a certain spatial distribution:Danjiang Reservoir Area>Hanjiang Reservoir Area>rivers.Among the heavy metal elements,the enrichment levels rank as following:Ba>Sr>Zn>V>Mn>Cu>Pb>As>Cr,while Ni and Rb show no obvious enrichments.From the results of principal component analysis and cluster analysis,Cr,As,V and Ni may origin from natural geochemical process,while Zn,Mn,Sr,Cu,Ba,Rb and Pb are subject to metallurgy industry.The risk assessment results show that the heavy metals pollution risks are mainly from a few heavy metal elements,such as Cu,Zn,Sr,etc.,in Han River,the entrance,and the central sampling points of Danjiang Reservoir,while Danjiangkou Reservoir has lower environmental risk of heavy metals in the sediments,and the overall condition is better.