新疆准东矿区土壤与降尘重金属空间分布及关联性分析

Spatial distribution analysis of heavy metals in soil and atmospheric dust fall and their relationships in Xinjiang Eastern Junggar mining area

土壤重金属与大气降尘重金属之间的关联性可以反映重金属污染的来源、土壤-大气系统中重金属的传输、迁移和扩散特征。为了研究矿区表层土壤的污染状况及与降尘重金属质量分数间的关联性,该研究以新疆维吾尔自治区准东矿区为研究靶区,利用2014年采集的51个表层土壤和大气降尘样品的室内实测重金属质量分数数据,并基于此分析了样品中6种重金属(As、Cu、Cr、Hg、Pb、Zn)的空间分布特征、地积累指数以及潜在生态风险;利用Pearson相关性分析矩阵和灰色关联法对表层土壤与大气降尘中重金属浓度的相关性和关联度进行探讨。结果表明:1)准东矿区表层土壤重金属的分布状况存在着明显的空间差异,其中Hg的污染程度最严重,处于强-极强度污染,其潜在生态危害指数达到了较高生态风险;Zn和Cu基本处于无污染状态,属于轻微生态风险;2)大气降尘重金属空间分布存在着明显差异,降尘中的Zn处于极强度污染,Hg处于无污染状态;3)Pearson相关分析与灰色关联分析表明,准东地区表层土壤与大气降尘中6种重金属的相关系数大小顺序与关联度排序结果一致,其中Hg和As元素具有较强的一致性,且具有相同的来源,说明大气降尘对表层土壤中重金属的质量分数有一定影响。但因不同重金属元素沉降特性不同,导致各元素之间的关联度有所差异。

Heavy metal pollution is the representative environmental pollution which is caused by heavy metals or their compounds.It has wide range,long duration,non-degradability,and some other features.The accumulation of heavy metals in soil will destroy the physical and chemical properties of soil,cause irreversible pollution of environment,and further threaten human health.For mining area,influenced by human exploitation,the top soil is thin and is easily affected by atmospheric dust fall.The relationship between soil heavy metals and atmospheric dust fall could reflect the sources of heavy metals pollution.Furthermore,the transport,migration and diffusion characteristics of heavy metals in the soil-atmosphere system could be revealed through the analysis of it.Existing work has mostly focused on only top soil,which might ignore the influence of dust reduction.Therefore,this study aimed to investigate the pollution status of heavy metals in the surface soil and their relevance with atmospheric dust fall.With51surface soil samples and51atmospheric dust fall samples collected from Eastern Junggar coal mining area in Xinjiang Uygur Autonomous Region,China,the contents of6kinds of heavy metals(As,Cu,Cr,Hg,Pb,and Zn)in the samples were measured in the laboratory.The geo-accumulation could be used to evaluate the pollution degree of heavy metals in soil.The potential ecological risk index takes into account the difference of the background values of heavy metals and the migration and transformation of heavy metals in the environment.The descriptive statistics of heavy metals in surface soil were carried out.Secondly,the spatial distribution,geo-accumulation,and potential ecological risk index of heavy metal from surface soil and atmospheric dust fall were analyzed.The outcomes of the analysis of them were described by ArcGIS10.1spatial analysis with inverse distance weighted(IDW)interpolation method.Subsequently,the correlation between surface soil and atmospheric dust fall was analyzed by Pearson correlation analysis and grey correlation analysis.Pearson correlation coefficient has been widely used to measure the linear relationship between fixed distance variables,and the value range is from-1to1;the greater the absolute value,the stronger the correlation.For the grey relational analysis,if the correlation degree was greater than0.6,the2factors could be regard as being correlated significantly.The results showed that:1)There were significant spatial distinctions between6kinds of heavy metal elements(As,Cu,Cr,Hg,Pb,and Zn)in surface soil.The pollution level of Hg was the most serious,which could be regard as the strong polar pollution,and its potential ecological risk index reached a high ecological risk.The Zn and Cu were basically in a state of no pollution,and they were at a slight ecological risk.2)There were obvious differences in the spatial distribution of heavy metals in atmospheric dust fall.The Zn in atmospheric dust fall was in pollution with extreme intensity,while Hg was in no pollution state.3)Pearson correlation coefficients showed that Hg and As in the atmospheric dust fall were significantly related to the As in soil,and the correlation coefficients reached0.72and0.66,separately.The results of grey correlation degree showed that the relevance between heavy metal in surface soil and atmospheric dust was notable,but varied among6kinds of heavy metal elements.The amount of local dust was related to human production activities and local climatic factors closely,i.e.,prevailing winds and precipitation.Therefore,in further research,the size of samples will be expanded,and this important factor will be used to analyze the spatial distribution,geo-accumulation,and potential ecological risk index of heavy metals,and explore the impact of dust on it.