Soil heavy metals in a typical coal mining cluster of Northern China: Pollution, source apportionment, and eco-health risks

From risk to response: Causal effects of soil heavy metal ecological risk on microbial community assembly in mining area.

Accurate ecological risk assessment is essential for pollution prevention and risk control of heavy metals (HMs) in mining areas. Herein, a hierarchical ecological risk assessment framework integrating source apportionment, risk characterization, and bacterial community analysis was proposed, and causal pathways between HM risk and bacterial diversity was established using Mantel analysis and structural equation modeling. Source apportionment revealed As, Cd, Cu, Pb and Zn in industrial land and nearby agricultural soils were primarily influenced by mining activities, whereas those in distant agricultural soils were governed by agricultural and mining activities. Unlike traditional indices, site-specific risk quotient provided more realistic ecological risks. The potentially affected fractions (PAFs) for As, Cd, Cu, Pb, and Zn were 25.44%, 2.42%, 39.76%, 13.42%, and 18.06%, respectively, while multi-substance PAF (msPAF) for HMs ranged from 27.34% to 98.98%. The distributions of both PAF and msPAF decreased outward from mining area, exhibiting a concentric circular pattern. Chloroflexota was the most dominant phylum, followed by Pseudomonadota, Bacillota, Actinomycetota, and Acidobacteriota. Causal inference revealed that indirect soil degradation contributed more to alterations in bacterial α-diversity compared with direct effects of msPAF-based risks. Collectively, these findings provide an effective hierarchical risk assessment methodology applicable to similar mining areas.

The Potential Heavy Metal Pollution Transfer to Surface Water and Groundwater in an Old Mining Area of Hubei, China

As a typical historical mining city, Daye, Hubei, faces potential heavy metal migration risks from legacy mining activities. This study conducted a grid-based survey in 2020, analyzing 389 soil and 137 water samples using the Nemerow Pollution Index (NPI) and spatial statistics to assess pollution and transfer mechanisms. Results show that soils were significantly contaminated (average NPI = 5.40), with 71.03% of samples exceeding the pollution threshold (NPI > 1), whereas surface water (0.18) and groundwater (0.11) maintained good quality. Despite limited direct soil migration, atmospheric wet deposition was identified as the probably dominant pathway driving higher concentrations of Cu, Cd, Pb, and As in surface water than in groundwater (e.g., on average, Cu and Cd levels in surface water were ~1.7-fold and ~5-fold those in groundwater, respectively, all well below Class III limits of national water quality standards). This study clarifies the mechanism protecting water bodies amid severe soil contamination and provides a scientific basis for integrated soil–water management in post-mining regions.

Study on Spatial Distribution Characteristics, Health Risk Assessment, and Source Apportionment of Heavy Metals in Soils of Tungsten Mining Areas in Southern Anhui Province

To investigate soil heavy metal pollution in tungsten mining areas of southern Anhui Province, this study selects a typical mining area as the research object. Tungsten resources are closely related to advanced engineering applications, including electromagnetic materials, microwave devices, and high-performance electronic components; therefore, environmental assessment of mining areas has practical significance for sustainable resource utilization. The results show that the average contents of W, As, and Cd in the soils of the study area are 186.25 mg/kg, 27.36 mg/kg, and 1.28 mg/kg, respectively, which are much higher than the soil background values of Anhui Province. In terms of spatial distribution, the pollution presents a pattern of high values in the central mining area and low values in surrounding areas, with high-value zones mainly concentrated around open-pit mines and tailings ponds. The average potential ecological risk index is 456.32, indicating a high ecological risk level, and Cd and As are identified as the main pollution factors. Health risk assessment shows that, after correction using the Total Toxic Dose (TTD) model, the average health index (HI) of children is 1.28, with crop consumption as the main exposure pathway. The findings provide a scientific basis for soil pollution control and environmental management in tungsten mining areas, and support sustainable development of resource supply chains related to electromagnetic and microwave engineering materials.

Multi-compartment Assessment of Lead Contamination and Ecological Risk in Soils, Sediments, Surface Waters, and Mining Residues of a Semiarid Mining–Agricultural Region in Mexico

Integrated assessment of groundwater quality suitability and heavy metal-induced health risks during the post-monsoon season near coal mining areas, Jharkhand, India

Source–Sink Relationships and Environmental Risks of Surface Soil Heavy Metals and Metalloids: Multi-Media Monitoring in a Southwest China County

The pollution of soil by potentially toxic elements in industrial–agricultural transition zones threatens global food security and public health owing to their persistence and bioaccumulation. This study focused on Miyi County, Sichuan (China), a typical region with intensive vanadium–titanium magnetite mining and modern agriculture, and systematically analyzed eight heavy metals and metalloids (Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni) across the categories of atmospheric deposition, irrigation water, agricultural inputs, and soil–crop systems. A rigorous four-stage full-chain diagnosis (concentration–load–ecology–health) was executed to evaluate pollution levels and pathways. The single-factor pollution index identified cadmium (Cd) as the primary pollutant, exhibiting a maximum index of 32.63. The Håkanson potential ecological risk index (RI) demonstrated that Cd was the absolute dominant contributor, reaching a catastrophic single-element risk factor (Ei) of 2191.8 and contributing over 70% to the comprehensive ecological risk. Spatially, soils displayed a distinct point-source cluster diffusion pattern: the northern metallurgical zone was dominated by a Cr-Zn-Cu-Ni industrial assemblage, while the southern zone was enriched in Cd, Pb, As, and Hg. Positive matrix factorization (PMF) source apportionment quantitatively demonstrated that industrial emissions via atmospheric deposition were the primary driver, contributing 55–75% of the total soil exogenous inputs, while agricultural sources (livestock manure and legacy arsenic pesticides) exacerbated localized accumulation. While overlying irrigation water remained safe, channel sediments acted as historical pollution sinks. The human health risk model revealed that children in industrial core areas faced unacceptable carcinogenic hazards, with a lifetime carcinogenic risk (LCR) reaching 5.6 × 10−4. These highly specific multi-media findings support a macro spatial risk zoning and source interception strategy to decouple economic growth from regional food safety degradation in global transition economies.