重庆市某钢铁厂污染场地土壤重金属污染评价及源解析

Pollution assessment and source apportionment of heavy metals in soil of a steel plant contaminated site in Chongqing City

  • 摘要: 为探究钢铁厂污染场地土壤重金属污染程度及污染来源,以重庆市某钢铁厂为例,采用系统性样点布设法在厂区内采集356个表层(0~0.30 m)土壤样品,分析样品中Hg、Cu、Cd、Pb、Zn、As、Ni、Cr共8种重金属浓度,运用单因子污染指数法、改进内梅罗综合污染指数法、相关性分析、主成分分析与PMF模型,并结合克里金(Kriging)空间插值对钢铁厂污染场地土壤重金属污染状况、分布特征及其污染源进行评价分析。结果表明:研究区内8种重金属浓度均值均高于重庆市土壤环境背景值,其中Hg、Cu较为明显,样本超标率分别达71.91%、64.61%。空间分布表明,土壤重金属浓度呈现以厂区为污染中心、向四周辐射的趋势。土壤重金属污染评价指数显示,Hg、Cu污染严重,单个重金属污染程度顺序为Hg>Cu>Cd>Pb>Zn>As>Ni>Cr,研究区综合污染较严重,污染占比达到86.52%,其中西南部和中部地块污染程度较为严重,污染程度高等级地带多位于厂区及其周围环境,表明研究区土壤中重金属浓度受到人为因素干扰。主成分分析和PMF模型显示,As、Cd、Zn、Pb和Cr主要来自工业和自然综合源,Cu和Ni主要为工业源,Hg的来源较复杂。土壤重金属污染防治分区显示,研究区整体处于严格管制区。研究区土壤重金属浓度普遍高于背景值,以Hg、Cu污染最为严重,污染呈厂区为中心向四周扩散,主要源于工业活动,后续防治修复过程应注重对Hg、Cu的风险管控。

     

    Abstract: To scientifically investigate the degree and sources of heavy metal pollution in the soil of a steel plant contaminated site, this study selected a steel plant in Chongqing as a case study. A systematic sampling design was employed to collect 356 surface (0~0.30 m) soil samples within the plant area. The concentrations of eight heavy metals (Hg, Cu, Cd, Pb, Zn, As, Ni, Cr) in the samples were analyzed. The pollution status, distribution characteristics, and sources of heavy metals in the steel plant's contaminated soil were evaluated and analyzed using the Single Factor Pollution Index method, the Modified Nemerow Comprehensive Pollution Index method, correlation analysis, principal component analysis (PCA), and the Positive Matrix Factorization (PMF) model, combined with Kriging spatial interpolation. The results showed that the average concentrations of the eight heavy metals in the study area were all higher than the background values of Chongqing's soil environment, with Hg and Cu being particularly prominent, having standard exceedance rates of 71.91% and 64.61%, respectively. Spatial distribution indicated that soil heavy metal concentrations showed a trend of radiating outward from the plant area as the pollution center. The soil heavy metal pollution assessment indices revealed severe pollution of Hg and Cu, with the single heavy metal pollution degree ranked as Hg > Cu > Cd > Pb > Zn > As > Ni > Cr. The comprehensive pollution in the study area was serious, accounting for 86.52% of the area, with the southwest and central plots being more severely polluted. The high-pollution areas were mostly located in the plant area and its surrounding environment, indicating that the heavy metal contents in the soil were influenced by anthropogenic factors. Principal component analysis and the PMF model demonstrated that As, Cd, Zn, Pb, and Cr primarily originated from industrial and natural comprehensive sources, Cu and Ni were mainly from industrial sources, while the sources of Hg were relatively complex. The zoning for soil heavy metal pollution control indicated that the entire study area was under strict control. The heavy metal contents in the soil of the study area were generally higher than the background values, with Hg and Cu pollution being the most severe. The pollution was spreading outward from the plant area as the center, primarily originating from industrial activities. The subsequent prevention, control, and remediation processes should focus on the risk management of Hg and Cu.

     

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