Evaluation and analysis of potential toxic elements (PTEs) distribution in abandoned soil affected by deep mining

Coal mining activities have demonstrated substantial environmental contamination, posed severe risks and impacted to the surrounding soil ecosystems. However, the effects of a single crack particularly during its initial stage of formation caused by deep mining-induced cracks, which fundamentally modify soil structure and affect PTE concentrations near coal mining, are poorly understood. Understanding this redistribution is essential for assessing environmental risks and developing remediation strategies. Soil samples were collected along primary crack zones in abandoned subsidence affected soils in Shandong Province, China, and analyzed using ICP-MS for seven PTEs to evaluate geo-accumulation index, spatial distribution and potential health risk. The result showed that concentrations of As, Ni, Cr, and Zn exceeded Shandong background levels by 1.32, 1.14, 1.07, and 1.05 times, respectively, indicating anthropogenic enrichment. The Soil was slightly contaminated by As, Ni, and Cu based on geo-accumulation index. Spatial analysis presented that all PTEs had strong spatial similarity, revealing a high concentration in the deep main crack, whereas Hg exhibits a distinct distribution behavior. Except mercury, statistical correlation among PTEs indicating common geochemical pathways. Health risk assessment of PTEs showed that children face exposure risks, particularly from oral ingestion of As with risk of 2.06 × 10^-5. These findings demonstrate that subsidence-related cracking plays a critical role in modifying distribution of potential toxic elements in abandoned soils and elevated health risk of arsenic for children, providing essential knowledge for risk mitigation and land management strategies in mining-disturbed regions.