摘要
为了解沮河流域(黄陵段)河岸带土壤重金属特征,在沮河流域(黄陵段)河岸带采集了12个样带共计84个土壤样品,分析了 8种重金属(砷(As)、镉(Cd)、铬(Cr)、铜(Cu)、汞(Hg)、铅(Pb)、镍(Ni)和锌(Zn))的含量状况及分布特征,利用单因子指数法、内梅罗综合指数法和地累积指数法对重金属污染程度进行评价,采用潜在生态风险指数法评价研究区生态风险程度,综合Pearson相关性分析和主成分分析法,定性分析8种重金属的来源.结果表明,沮河流域(黄陵段)河岸带土壤中,Pb、Cu、Zn、Ni和As存在轻微富集现象,Cd和Hg的污染最为严重,平均值为0.134 mg·kg-1和0.066mg·kg-1,点位超标率分别达到了 100％和58.3％.Pb、Cd、Zn、Cu和Hg等元素的含量在空间上分布相似,即从上游到下游为先递增后递减的趋势,而Ni和Cr两种元素的含量却呈现先递减后递增的趋势.As元素的含量从上游到下游一直呈递减趋势.3种典型土地利用河岸带的重金属横向分布规律呈现出一定的相似性,均呈现出随着高程的降低先增加后减小的趋势.坡度和径流是影响重金属迁移的重要因素.污染评价和生态风险评价表明,Cd和Hg两种重金属元素存在较高的污染等级,分别达到了Ⅲ级和Ⅴ级,Cd和Hg两种重金属元素的潜在生态风险较高,其中Cd为Ⅳ级,Hg为Ⅴ级.相关性分析和主成分分析结果表明,As、Pb、Cd、Cu和Zn主要受农业生产、交通运输、工业生产的影响,为人为源;Cr和Ni的污染源主要为自然源,如地质活动和成土母质;Hg的主要来源为大气沉降.
Abstract
To understand the characteristics of heavy metals in the riparian zone of Juhe River Basin(Huangling Section),a total of 84 soil samples were collected from 12 transects in the riparian zone of Juhe River Basin(Huangling Section).The content status and distribution characteristics of eight heavy metals(Arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),mercury(Hg),lead(Pb),nickel(Ni),and zinc(Zn))were analyzed.The degree of heavy metal pollution was evaluated using the single factor index method,Nemerro composite index method,and geo-accumulation index method.The potential ecological risk index method was used to assess the ecological risk in the study area.Pearson correlation analysis and principal component analysis were employed to qualitatively analyze the sources of the eight heavy metals.The results showed that Pb,Cu,Zn,Ni,and As were slightly enriched in the riparian soil of Juhe River Basin(Huangling section),while Cd and Hg exhibited the most serious pollution,with exceedance rates of 100％and 58.3％respectively.The spatial distribution of Pb,Cd,Zn,Cu,and Hg showed an increasing trend from upstream to downstream,followed by a decrease,while the content of Ni and Cr decreased first and then increased.The content of As elements decreased from upstream to downstream.The horizontal distribution of heavy metals in the three typical land use riparian zones showed a certain similarity,and all showed a trend of first increasing and then decreasing with the decrease of elevation.Slope and runoff are important factors affecting heavy metal migration.Pollution evaluation and ecological risk assessment showed that the two heavy metal elements of Cd and Hg had high pollution levels,reaching grade Ⅲ and Ⅴ.respectively,and the potential ecological risks of Cd and Hg were higher,among which Cd was grade Ⅳ andHg was grade Ⅴ.The correlation analysis and principal component analysis revealed that As,Pb,Cd,Cu,and Zn were primarily influenced by agricultural production,transportation,and industrial activities,indicating anthropogenic sources.The pollution sources of Cr and Ni were mainly natural,such as geological activities and soil parent materials,while atmospheric deposition was the main source of Hg.
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