鸭绿江口近百年来重金属垂向沉积的污染评价

以鸭绿江口西汊道连续性较好、时间分辨率较高、以海湾性质为主的沉积柱状样为样本,对其沉积速率、粒度、重金属质量分数进行了测定和分析,并结合210Pb测年结果对试验数据进行了相关分析和聚类分析,同时采用地累积指数法对鸭绿江口近百年来重金属的垂向沉积进行了污染评价.结果表明:鸭绿江河口的重金属污染除Cu外都呈逐年增加的趋势,体现了人类活动在自然演变中的强烈响应;粒度不是控制鸭绿江河口重金属积累的唯一因素,除w(Cu)和w(As)外,w(Hg)、w(Cr)、w(Ni)、w(Zn)、w(Pb)及w(Cd)之间有着较好的相关性,说明这些重金属元素有较为一致的沉积环境.大多数重金属受控于工业和农业的污染物排放,而Cu主要来源于采矿污染.用中朝地台页岩作为背景值进行地累积指数的污染评价表明,大多数重金属污染级别目前已达到中等到强的程度,说明鸭绿江口的重金属污染正在日益加重. 

Pollution Evaluation of Vertical Sediments in the Yalu River Estuary over the Past Century

The sedimentation rate,grain size and contents of heavy metals were measured and analyzed with high time resolution for the core of mainly gulf sediments in the western branch of Yalu River.Combined with 210Pb dating data,correlation and cluster analyses on the experimental data were performed.In addition,pollution evaluation of the vertical sediments was performed using a geoaccumulation index.The results showed that,with the exception of Cu,the pollution of all the other heavy metals were increasing in the Yalu River estuary,which indicated a large impact of human activities on the natural evolution.Grain size was not the only factor influencing the accumulation of heavy metals.The results showed that,with the exception of Cu and As,there was good correlation among Hg,Cr,Ni,Zn,Pb and Cd,which were in good agreement with their local sediment environment.The concentrations of most heavy metals were controlled by industrial and agricultural pollution,while Cu mainly originated from mineral pollution.Based on the background values of the Sino-Korean Platform shale,the pollution levels of most heavy metals were determined to be medium to high,which indicated increasingly serious heavy metal pollution in the Yalu River estuary.