长江口南支表层沉积物重金属含量、空间分布与生态风险评价

Contents,spatial distribution and ecological risk assessment of heavy metals in surface sediment from the south branch of the Yangtze Estuary

摘要:

为探究长江口南支水域表层沉积物重金属元素含量和空间分布变化,分析测定了研究区域2018—2022年表层沉积物中铜(Cu)、锌(Zn)、铅(Pb)、铬(Cr)、镉(Cd)、汞(Hg)及砷(As)的含量,并借助地统计学空间分析方法,对研究区域的重金属元素含量进行变异分析和空间分布模拟。结果显示:Zn、Cr、Cu、Pb、As、Cd、Hg的含量变化范围分别是23.539~101.955 mg/kg、14.390~88.672 mg/kg、3.325~40.441 mg/kg、7.788~26.145 mg/kg、5.035~12.610 mg/kg、0.072~0.436 mg/kg、0.004~0.171 mg/kg,2021年重金属元素含量明显高于其他年度,元素空间相关性年际变化较大。Cu、Zn、As高值区主要分布在研究区域的下游,Cd高值区主要分布在中游,Cr高值区主要分布由下游变为中游,Pb高值区主要分布由下游变为中、下游。重金属生态风险表现为Hg生态风险等级上升,Cu中等生态风险持续存在且范围扩大,Cr中等生态风险间歇性出现。

Abstract:

To explore the contents and spatial distribution changes of heavy metals in the surface sediment from the south branch of the Yangtze Estuary,the concentrations of Cu,Zn,Pb,Cr,Cd,Hg and As of study area were analyzed from 2018 to 2022,and the spatial variation analysis and distribution simulation of heavy metals were carried out using geostatistics.The results showed that the concentrations of Zn,Cr,Cu,Pb,As,Cd and Hg were 23.539-101.955 mg/kg,14.390-88.672 mg/kg,3.325-40.441 mg/kg,7.788-26.145 mg/kg,5.035-12.610 mg/kg,0.072-0.436 mg/kg and 0.004-0.171 mg/kg,respectively.The heavy metal contents in 2021 were significantly higher than those in the other years,and the spatial correlation of elements varied greatly according to different years.The high-value area of Cu,Zn and As located in downstream of study area,and high-value area of Cd located in the middle stream.The high-value area of Cr changed from downstream to middle stream,and for Pb,it expanded from downstream to middle stream.The ecological risk assessment showed that the ecological risk level of Hg exhibited a rising trend,the medium ecological risk of Cu expanded its area and the medium ecological risk of Cr appeared occasionally during the experiment.