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<p>The rapid expansion of global transportation infrastructure has significantly increased tunnel construction in mountainous regions, generating substantial amounts of sulfide-rich excavation waste. Current disposal practices relying on open-air storage pose critical environmental risks through land occupation and potential heavy metal pollution, while the intrinsic pollutant release mechanisms from sulfide mineral weathering remain insufficiently investigated. This study elucidates a novel pollution pathway through photocatalytic oxidation-triggered heavy metal liberation in tunnel waste. Conducted comprehensive mineralogical characterization of sulfide-bearing tunnel residues and systematically examined heavy metal migration patterns under controlled photooxidative conditions (variable illumination duration, temperature (25–45 °C), moisture content (20–60%), and aeration status). Parallel experiments monitored pH evolution and heavy metal release kinetics, particularly focusing on Cd, As, Cr, Pb, and Mn. Results revealed the presence of photochemically active Fe- and Ti-bearing phases in sulfide matrices that drive acid generation through solar-induced sulfite oxidation. This catalytic process established strongly acidic conditions (pH 2.0 ± 0.3) under optimal parameters: 35 °C, 40% moisture content, and 48-h photoexposure with aeration. The resultant acidification promoted mineral dissolution, yielding maximum leachate concentrations of 0.09 mg/L Cd, 1.8 μg/L As, 0.05 mg/L Cr, 0.36 mg/L Pb, and 8.54 mg/L Mn, representing 3–eightfold increases compared to dark controls. This work provides the first mechanistic evidence of photocatalysis-mediated acid mine drainage formation in tunnel waste systems, challenging conventional geochemical weathering paradigms. The findings establish a theoretical framework for predicting heavy metal pollution risks and inform remediation strategies through photochemical parameter control, ultimately supporting sustainable management of tunnel excavation byproducts.</p>

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Analysis of heavy metal pollution sources caused by sulfide minerals in tunnel waste under photocatalytic oxidation conditions

  • 期刊论文

  • 发表日期：

    2025年4月12日

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  • Xinzhu Yi,
  • Fenghui Wu,
  • Jinrong Zhang,
  • Song Xue,
  • Mingquan Zhou,
  • Xin Li,
  • Hao Chen

摘要

The rapid expansion of global transportation infrastructure has significantly increased tunnel construction in mountainous regions, generating substantial amounts of sulfide-rich excavation waste. Current disposal practices relying on open-air storage pose critical environmental risks through land occupation and potential heavy metal pollution, while the intrinsic pollutant release mechanisms from sulfide mineral weathering remain insufficiently investigated. This study elucidates a novel pollution pathway through photocatalytic oxidation-triggered heavy metal liberation in tunnel waste. Conducted comprehensive mineralogical characterization of sulfide-bearing tunnel residues and systematically examined heavy metal migration patterns under controlled photooxidative conditions (variable illumination duration, temperature (25–45 °C), moisture content (20–60%), and aeration status). Parallel experiments monitored pH evolution and heavy metal release kinetics, particularly focusing on Cd, As, Cr, Pb, and Mn. Results revealed the presence of photochemically active Fe- and Ti-bearing phases in sulfide matrices that drive acid generation through solar-induced sulfite oxidation. This catalytic process established strongly acidic conditions (pH 2.0 ± 0.3) under optimal parameters: 35 °C, 40% moisture content, and 48-h photoexposure with aeration. The resultant acidification promoted mineral dissolution, yielding maximum leachate concentrations of 0.09 mg/L Cd, 1.8 μg/L As, 0.05 mg/L Cr, 0.36 mg/L Pb, and 8.54 mg/L Mn, representing 3–eightfold increases compared to dark controls. This work provides the first mechanistic evidence of photocatalysis-mediated acid mine drainage formation in tunnel waste systems, challenging conventional geochemical weathering paradigms. The findings establish a theoretical framework for predicting heavy metal pollution risks and inform remediation strategies through photochemical parameter control, ultimately supporting sustainable management of tunnel excavation byproducts.