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<p>The chemical speciation of heavy metals (HMs) is key to determining their bioavailability and toxicity. Traditional source apportionment and risk assessment of soil HMs based on total concentrations often overestimate the actual risks. This study selected the soils in the multi-contaminated area with high geological background and lead–zinc smelting activities in northwestern Guizhou, Southwest China, as the research object and established a source-specific risk assessment framework based on bioavailability for six HMs (Cd, Pb, Zn, Cu, Cr, Ni). Results showed that the residual fraction (F4) accounted for over 80% of Cr, Ni, and Cu, while the total proportion of acid-soluble fraction (F1) and reducible fraction (F2) was relatively high for Cd, Pb, and Zn, with Cd exceeding 40%. The positive matrix factorization (PMF) model identified three primary sources of bioavailable HMs: mixed source related to lead–zinc smelting and transportation (45.6%), natural source (31.1%), and agricultural source (23.3%). Compared with source apportionment based on total concentrations, the contribution of the mixed source related to lead–zinc smelting and transportation increased by 12.7%, while that of the natural source decreased by 7.0%. Health risk assessment revealed that the total concentrations-based carcinogenic risk (TCR) was unacceptable, whereas the non-carcinogenic risk (HI) was negligible, with children facing higher risks than adults. In contrast, bioavailable concentrations-based HI and TCR were 72.9%–76.9% and 46.5%–78.4% lower, respectively. The non-carcinogenic and carcinogenic risks from all pollution sources were acceptable. The mixed source related to lead–zinc smelting and transportation contributed the highest proportions to HI (73.06%) and TCR (62.26%), with Cd and Pb identified as the primary contributing elements. This study highlights bioavailable concentrations as a more reliable parameter for soil HMs source-specific health risk assessment, providing a scientific basis for targeted HMs source control and precise cultivated soil risk management in areas with overlapping high geological backgrounds and anthropogenic activities.</p>

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Bioavailability-based source apportionment and source-specific risk assessment of heavy metals in cultivated soils from high geological background and lead–zinc smelting areas

  • 期刊论文

  • 发表日期：

    2026年5月20日

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  • Huanhuan Wang,
  • Hongyan Liu,
  • Pan Wu,
  • Xuexian Li

摘要

The chemical speciation of heavy metals (HMs) is key to determining their bioavailability and toxicity. Traditional source apportionment and risk assessment of soil HMs based on total concentrations often overestimate the actual risks. This study selected the soils in the multi-contaminated area with high geological background and lead–zinc smelting activities in northwestern Guizhou, Southwest China, as the research object and established a source-specific risk assessment framework based on bioavailability for six HMs (Cd, Pb, Zn, Cu, Cr, Ni). Results showed that the residual fraction (F4) accounted for over 80% of Cr, Ni, and Cu, while the total proportion of acid-soluble fraction (F1) and reducible fraction (F2) was relatively high for Cd, Pb, and Zn, with Cd exceeding 40%. The positive matrix factorization (PMF) model identified three primary sources of bioavailable HMs: mixed source related to lead–zinc smelting and transportation (45.6%), natural source (31.1%), and agricultural source (23.3%). Compared with source apportionment based on total concentrations, the contribution of the mixed source related to lead–zinc smelting and transportation increased by 12.7%, while that of the natural source decreased by 7.0%. Health risk assessment revealed that the total concentrations-based carcinogenic risk (TCR) was unacceptable, whereas the non-carcinogenic risk (HI) was negligible, with children facing higher risks than adults. In contrast, bioavailable concentrations-based HI and TCR were 72.9%–76.9% and 46.5%–78.4% lower, respectively. The non-carcinogenic and carcinogenic risks from all pollution sources were acceptable. The mixed source related to lead–zinc smelting and transportation contributed the highest proportions to HI (73.06%) and TCR (62.26%), with Cd and Pb identified as the primary contributing elements. This study highlights bioavailable concentrations as a more reliable parameter for soil HMs source-specific health risk assessment, providing a scientific basis for targeted HMs source control and precise cultivated soil risk management in areas with overlapping high geological backgrounds and anthropogenic activities.