Multi-compartmental migration and ecological-health risks of trace metals in Dexing mining concentration areas: A holistic quantitative assessment

Abstract

To address the critical gap in linking multi-compartmental transfer with risks of trace metals (Cd, Pb, As, Cr, Ni) in mining environments. This study systematically investigated the trans-media migration of Cd, Pb, As, Cr, and Ni in China’s Dexing copper mining district through paired sampling of water-amphibians, soil-earthworms, and air-lichens. Advanced methodologies were employed, including ICP-MS quantification for heavy metals, geochemical indices (Igeo, BCF, BAF) to assess bioavailability, NMDS for source apportionment, and HPLC to detect DNA methylation alterations. Aquatic systems exhibited severe Cd/Pb enrichment (16.25-24.42 μg/L; 11-15× WHO limits), while agricultural soils showed extreme Cd contamination (1.5 mg/kg; 15× background). Biota displayed metal-specific accumulation: frogs achieved BCFs >1,000 for Pb/Cd, earthworms showed pH-modulated BAFs >2.5 for Cd/As, and lichens recorded 100-1,000× atmospheric Cr enrichment. NMDS resolved three contamination pathways: mining-derived Cd/Pb/As (MDS1 = 2.56), atmospheric Cr (PC2 = 1.84), and geogenic Ni. Cd dominated ecological risks (Eri = 554.25; RI 300), while atmospheric Cr drove carcinogenic risks (TCR = 4.11×10⁻⁵) exceeding safety thresholds. The source-media-biota-risk framework pioneers the integration of geochemical transport with epigenetic toxicity biomarkers, demonstrating that sub-lethal Cd/Pb exposure induces genome-wide DNA hypomethylation (2.4%-6.6% reduction; ρ = −0.71 to −0.91). This paradigm shift prioritizes bioavailability-informed regulations over concentration-based metrics, offering actionable strategies for sustainable development goals-aligned mining pollution control.

Keywords

Copper mining operations / Trace metal(loid)s contamination / Cross-media transfer / Water-amphibians / Soil-earthworms / Air-lichens / DNA methylation biomarkers / Biogeochemical processes / Risk assessment / Sustainable Development Goals (SDG3) / Dexing mining area / Environmental geological survey engineering

CRediT authorship contribution statement

Xiao-tao Zhang conceptualized the entire paper and prepared the manuscript. Man-dan Huang participated in the drawing illustrations and preparation of manuscript. Bin Shen and Zhi-hang Xin participated in the conception and article verification. Shan-hong Lan and Jun-jie Hu supervised the field investigation and sample collection of the whole project.

Declaration of competing interest

The authors declare no conflict to interest.

Acknowledgments

The present work was financially supported by the Fundation of Key Laboratory of Ministry of Natural Resources for Eco-geochemistry (ZSDHJJ202202), and Geological Investigation and Evaluation of Shale Gas in Complex Structural Areas of the Middle Yangtze plate (DD20250200604) of China Geological Survey, the Natural Science Foundation of Guangdong Province, China (2023A1515140061), and the Dongguan Science and Technology of Social Development Program (20231800935842, 20231800940562).

Appendix A. Supplementary data

Supplementary data (Table S1-S13) to this article can be found online at doi: 10.31035/cg20250074.

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