基于GIS的滇东地区耕地土壤重金属空间分布与蔬菜安全评估

Spatial distribution of heavy metals in cultivated soils and vegetable safety assessment in eastern Yunnan based on GIS technology

  • 摘要: 以滇东地区6个市(州)为研究区域,系统采集了467个耕地土壤样本及叶菜类蔬菜可食用部分样本97例,对样本的pH、有机质等基础理化指标以及As、Hg、Cu、Zn、Pb、Cd、Cr等重金属元素含量进行实验室测定。基于单因子污染指数法和美国国家环境保护局(US EPA)健康风险评价模型,分别构建污染特征评价体系和健康风险评价模型,并借助ArcGIS 10.8软件开展重金属空间分布可视化分析。结果表明:1)重金属含量特征显示,除As外其余6种元素平均含量均超出云南省土壤背景值34%~97%,其中Cu(0.43倍)和Cd(0.78倍)超过农用地土壤污染风险筛选值。2)空间分析表明,Cd污染呈显著区域分异特征,以曲靖市为核心的滇中地区为重度污染区(Pi为3.12),昭通北部和文山南部构成中度污染带(Pi为1.85~2.43);Cu污染主要集中于中部(Pi为1.67),Zn、Pb复合污染则分布于中南部的昆明-玉溪过渡带(Pi为1.12~1.35)。3)健康风险评估显示,重金属经消化道和皮肤接触途径的致癌风险指数均低于安全阈值(10−4),但儿童群体非致癌风险指数(HI为1.26)显著高于成人(HI为0.87),其中曲靖市采样点HI达1.43,建议重点关注该区域农产品的重金属迁移机制。通过多维度风险评估,为构建滇东耕地土壤重金属污染防治体系及建立蔬菜安全预警机制提供科学依据。

     

    Abstract: This study systematically collected 467 cultivated soil samples and 97 leafy vegetable edible part samples from six prefectures in the eastern region of Yunnan Province. Laboratory analyses were conducted to determine basic physical and chemical indicators such as pH, organic matter, and concentrations of heavy metals (As, Hg, Cu, Zn, Pb, Cd, Cr). A pollution characteristic evaluation system and a health risk assessment model were established using the single-factor pollution index method and the United States Environmental Protection Agency (US EPA) health risk assessment model. Spatial distribution patterns of heavy metals were visualized using ArcGIS 10.8. Key findings included: (1) Average concentrations of six heavy metals (excluding As) exceeded Yunnan soil background values by 34%-97%, with Cu exceeding by 0.43 times and Cd by 0.78 times agricultural soil pollution risk screening thresholds. (2) Spatial analysis revealed significant regional Cd contamination, identifying the central region of Yunnan Province around Qujing City as a severe pollution zone (Pi=3.12), with moderate contamination belts in northern Zhaotong and southern Wenshan (Pi=1.85-2.43). Cu pollution clustered in the central region (Pi=1.67), while Zn-Pb composite pollution dominated the Kunming-Yuxi transitional zone in the central and southern regions (Pi=1.12-1.35). (3) Health risk assessment indicated that carcinogenic risks via ingestion and dermal pathways remained below the 10−4 safety threshold. However, non-carcinogenic hazard indices for children (HI=1.26) significantly exceeded adult values (HI=0.87), particularly in Qujing City (HI=1.43). This underscores the need to prioritize research on the translocation mechanisms of heavy metals in agricultural products. The multi-dimensional risk assessment provides scientific support for establishing heavy metal pollution prevention systems and vegetable safety early-warning mechanisms in eastern Yunnan's cultivated soils.

     

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