Search Results (437)

The sources of potentially toxic elements (PTEs) in the lower reaches of the Yellow River (LYR) remain poorly understood due to intensive human activities in this region. To elucidate the spatiotemporal distribution characteristics and sources of PTEs, water samples were collected from both mainstream and tributary sites during the dry season (DS) and flood season (FS). Concentrations of eight PTEs (Fe, Mn, Cu, Zn, Pb, As, Cr, and Hg) were determined. The single-factor pollution index, Nemerow comprehensive pollution index, statistical techniques, and the positive matrix factorization (PMF) receptor model were jointly employed to evaluate PTEs pollution levels and quantitatively apportion its sources. The results showed that PTEs concentrations in the mainstream were significantly higher than those in the tributaries, with Fe and Mn being the primary contaminants exceeding standards. During the DS, the mean concentrations of Fe and Mn were 1.33 mg/L and 0.34 mg/L, with exceedance rates of 100% and 84.2%, respectively. In contrast, both concentrations declined markedly in the FS (Fe: 0.27 mg/L; Mn: 0.112 mg/L). The PMF model identified three sources in the DS, with contribution rates of 42.1% (geogenic background and domestic sewage), 32.4% (industrial wastewater), and 25.5% (agricultural sources). In the FS, two sources were resolved, namely a mixture of non-point source pollution and domestic sewage (64.3%) and a mixture of geogenic background and industrial wastewater (35.7%). The pronounced increase in non-point source contribution during the FS highlights the role of rainfall runoff in driving pollutant input. This study provides a scientific basis for PTEs pollution control in the LYR. Full article

Despite their size, small wetlands play a vital role in maintaining ecosystem stability. To clarify the pollution levels as well as potential ecological and health risks of potentially toxic elements (PTEs) in small wetlands, 85 water samples were collected from small wetlands in the Baghrash Lake Basin (BLB) of China, and six PTEs (As, Cd, Cu, Hg, Pb, and Zn) were determined for their contents. The Nemerow integrated pollution index (NPI) was adopted to evaluate PTE pollution levels. The ecological risk index (RI) and USEPA health risk assessment model were further applied to quantify potential ecological and health risks of PTEs, respectively. The results revealed that PTEs in small wetlands showed a slight pollution level, with an average NPI value of 0.73. Meanwhile, the integrated ecological risk index of PTEs showed a low ecological risk level, with an average RI value of 23.041. Health risk assessment results demonstrated that the non-carcinogenic risk of PTEs in small wetlands remained at a negligible level, while the carcinogenic risk stayed within acceptable limits for both local population groups: children and adults. Among all detected PTEs, Hg was identified as the primary pollutant and major ecological risk factor, while As posed the highest relative potential health risk while overall risks remained acceptable. The findings of this study can provide a scientific basis for the environmental protection of small wetlands in the BLB. Full article

The agricultural and environmental application of Miscanthus × giganteus biomass ash (MBA) as a soil amendment requires a thorough assessment of its properties, nutrient potential, and associated risks. This study characterizes the elemental composition, pH, cation exchange capacity (CEC), and polycyclic aromatic hydrocarbons (PAHs) content of MBA in comparison with other common biomass ashes (crops, wood, and sewage sludge) referred to the international regulatory standards. The ash exhibits a strong alkaline pH (11.03), suggesting potential to improve soil pH in acid soils, but requires careful controlled application to prevent excessive alkalization. The main nutrients detected include K (5.54%), Ca (2.07%), Mg (0.37%), and P (0.86%), indicating its potential as a soil amendment, though long-term use may cause nutrient imbalances. Micronutrients such as Zn (240.67 mg·kg⁻¹), Mn (297 mg·kg⁻¹), and Cu (33.5 mg·kg⁻¹) are found in concentrations suitable for agricultural use, while potentially toxic elements (PTEs), including Cd, Cr, Ni, and Pb, are below detection limits, thereby reducing the risk of pollution. As (8.3 mg·kg⁻¹) and ΣPAHs (1.63 mg·kg⁻¹) remain within safety thresholds, suggesting a low environmental toxicity of MBA. The low Na content (0.12%) indicates a minimal risk of salinity accumulation, distinguishing MBA from high-sodium biomass ashes. Soil alkalization, disruptions in nutrient balance, and element leaching are risks to be considered. Despite these concerns, its composition is in agreement with established safety guidelines, supporting its feasibility for valorization as a sustainable soil amendment and remediation material. To maximize agronomic benefits and mitigate environmental risks, it is important to utilize the ash, considering site conditions and carry out regular monitoring of the soil. Full article

Areas where mining activities overlap with agricultural production may promote the mobilization of potentially toxic elements (PTEs) into soils and water resources, thereby creating exposure pathways for populations living or working in these environments. This study analyzes the concentration of PTEs in agricultural soils and irrigation water from Santa Rosa, southern Ecuador, and assesses the associated health risks for exposed agricultural workers. For this purpose, 35 soil samples were collected from farms and 12 water samples from the irrigation canal during the dry season of 2025. The concentration of PTEs in soil and water was determined using X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The PTE concentration in both matrices was compared with the maximum permissible limits (MPL) established by Ecuadorian regulations. Non-carcinogenic hazard indices ($\mathrm{H}\mathrm{I}$) and carcinogenic risk ($\mathrm{T}\mathrm{C}\mathrm{R}$) were estimated following the U.S. EPA methodology. In soil, As and Cr were the PTEs of greatest concern, exceeding the MPL in 93% of the samples and by up to 4.4 and 2.4 times, respectively, while in water, all PTEs were below the MPL. Non-carcinogenic risk was below the recommended limit for soil and water ($\mathrm{H}{\mathrm{I}}_{\mathrm{s}\mathrm{o}\mathrm{i}\mathrm{l}}$ = 3.00 × 10⁻² and $\mathrm{H}{\mathrm{I}}_{\mathrm{w}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}}$ = 2.00 × 10⁻³), with As as the dominant contributor. Cancer risk was tolerable in soil ($\mathrm{T}\mathrm{C}{\mathrm{R}}_{\mathrm{s}\mathrm{o}\mathrm{i}\mathrm{l}}$ = 4.34 × 10⁻⁵), while in water it remained at a low level ($\mathrm{T}\mathrm{C}{\mathrm{R}}_{\mathrm{w}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}}$ = 1.65 × 10⁻⁶). These findings identify As and Cr as priority contaminants and support targeted monitoring and source-control measures in mining-influenced agricultural areas. Overall, by integrating agricultural soil and irrigation water quality with an occupational health risk assessment in Santa Rosa, this study contributes evidence to support future research in mining–agriculture coexistence areas. Full article

Source apportionment and the elucidation of driving mechanisms are essential for targeted soil pollution management. This study investigated surface soils across six towns in southern Shimen County, northwestern Hunan Province, where 662 samples were collected to determine the concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn. Multivariate statistics and the APCS-MLR receptor model were integrated to quantify pollution sources, while three machine learning models (RF, XGBoost, and LightGBM) were applied to identify key drivers of the spatial enrichment of Cd. Results showed that Cd was significantly enriched, with a mean concentration of 0.43 mg/kg (3.41 times the provincial background value). The mean concentrations of As, Cr, Cu, Ni, Pb and Zn were 11.97 mg/kg, 81.01 mg/kg, 24.15 mg/kg, 49.25 mg/kg, 29.56 mg/kg and 76.77 mg/kg, respectively, and these PTEs remained at normal background levels. Significant inter-element correlations indicated common sources. Three primary sources were quantified—natural parent material (43.83%), mining activities (30.99%), and mixed sources of coal mining and agricultural inputs (7.84%), with 17.34% attributed to unidentified mixed sources. Natural sources dominated the geogenic enrichment of Cd, Cu, Ni, Pb, and Zn; mining activities governed the accumulation of As, Cr, Cu, and Pb; a mixed source of coal mining and agricultural practices contributed substantially to Cd enrichment. Machine learning identified PM10, topography, strata, and soil type as dominant drivers, with their total feature importance reaching 70.05%. Among these factors, natural factors and anthropogenic factors accounted for 44.23% and 55.77% of the total feature importance, in turn revealing coupled natural–anthropogenic controls. This study establishes an integrated framework linking source apportionment and driver identification, providing scientific insights for potentially toxic elements (PTEs) control in analogous mining–agricultural regions. Full article

Soil contamination by heavy metals (HMs) [or potential toxic elements (PTEs)] poses serious risks to ecosystems and human health. Metals persist in the environment and can reach groundwater and freshwater as part of the food-chain. In soils, anthropogenic inputs dominate over geogenic sources. Metal mobility is strongly controlled by factors such as pH, mineralogy, and erosion processes that transport metal-bearing clay fractions. Wind and water can transport soil, mainly clay particles that can usually bind contaminants such as HMs. Using waste material is a tool suggested from the circular economy, so waste becomes a valuable resource. This study evaluates the immobilization efficiency of several heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) using phosphate amendments—synthetic hydroxyapatite, phosphatic rock from Florida and Morocco—applied to a brownfield site. Heavy metal immobilization followed a two-step mechanism: first rapid surface complexation and secondly partial dissolution of hydroxyapatite and ion exchange with Ca, leading to the precipitation of metal-substituted hydroxyapatite phases. Synthetic hydroxyapatite generally shows the best efficiency, whereas phosphatic rocks were less effective but still provided a measurable immobilization. From a circular economy perspective, however, phosphatic rocks remain attractive due to their lower cost, availability, and waste-valorization potential. Full article

Soil vulnerability is commonly assessed using environmental indicators; however, the lack of systematic and continuous monitoring often leads to incomplete and fragmented data, particularly in surface coal mining areas affected by potentially toxic element (PTE) contamination. Existing studies mainly focus on impact assessment, with limited emphasis on structured decision-support frameworks for selecting optimal soil protection strategies. This study addresses this gap by proposing an integrated hybrid decision-making framework that combines the Analytic Hierarchy Process (AHP), Sustainability Balanced Scorecard (SBSC), and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The main contribution lies in integrating strategic sustainability perspectives (SBSC) with quantitative multi-criteria methods (AHP and TOPSIS), enabling a transparent and consistent evaluation of soil protection strategies across environmental, economic, technical, and social dimensions. The framework was applied to the Kostolac mining and energy complex in Serbia as a representative case study, using data from the State of the Environment Report as the basis for expert evaluation. The results identify risk reduction and environmental effectiveness as the dominant criteria, while the Progressive Strategy (SBSC) achieved the highest ranking. Sensitivity analysis confirmed the robustness of the model. From a policy perspective, the findings support prioritizing sustainability-oriented and risk-reduction strategies in mining regulations and investment planning. Full article

Potentially toxic elements (PTE) are persistent contaminants in coastal systems and may accumulate in marine organisms, with relevance for both environmental monitoring and seafood safety assessment. This study provides an exploratory cross-biota assessment of Cd, Cr, Cu, Ni, and Pb in fishery resources from the Romanian Black Sea in 2024. The dataset included 24 composite samples and 120 analyte-level observations across bivalves, gastropods, pelagic fish, and demersal fish. Tissue concentrations were integrated with regulatory maximum levels, bioconcentration factors (BCF), biota–sediment accumulation factors (BSAF), and adult dietary risk indices, including estimated daily intake (EDI), target hazard quotient (THQ), and total target hazard quotient (TTHQ). Within the limits of this single-year dataset, Cd and Pb concentrations were generally higher in bivalves than in fish and gastropods, whereas Cr showed higher values in several fish samples, particularly pelagic fish. Cd was the main element of concern, with regulatory exceedances occurring mainly in bivalves and fewer exceedances in pelagic fish, while Pb exceedance was isolated. BCF and BSAF supported the relevance of Cd as a priority element but were interpreted only as descriptive tissue–water and tissue–sediment ratios, not as evidence of specific uptake pathways. Low abiotic Cd concentrations may have inflated some ratio-based values, and Cr interpretation remains limited by the absence of Cr speciation and dissolved/particulate partitioning data. The adult dietary risk assessment did not indicate substantial non-carcinogenic concern, as all individual THQ values and cumulative TTHQ values remained below 1. Overall, the findings support continued PTE monitoring in the Romanian Black Sea, using sessile bivalves as indicators of local environmental contamination and including gastropods and representative pelagic and demersal fish species of ecological and fisheries relevance to capture contaminant patterns across benthic and mobile fishery resources. Future monitoring should improve species-level replication, integrate metal partitioning in abiotic matrices, and include additional contaminants of seafood safety relevance, particularly Hg and As. Full article

Potentially toxic element (PTE) contamination in rice poses significant food safety risks, particularly in regions with intensive agriculture, industry, and traffic. This study provides a systematic assessment of the accumulation, translocation, sources, and health risks of PTEs (As, Cd, Cr, Cu, Ni, Pb, Zn) in the atmospheric deposition–soil–rice system across four distinct anthropogenic source areas (industrial, peri-urban, rural, and roadside areas) in Hunan Province, China. The rural area was categorized as clean. Industrial areas had the highest soil pollution index, while roadside areas recorded the highest atmospheric deposition flux of Pb (19.95 μg/m²/day) and As (1.93 μg/m²/day). Correspondingly, industrial areas exhibited the highest Cd (0.38 mg/kg) and Pb (0.94 mg/kg) in rice grains, whereas roadside areas showed the highest Pb (1.40 mg/kg) and As (2.99 mg/kg) in leaves. The findings indicated that rice in roadside areas primarily accumulate PTEs through foliar absorption of atmospheric deposition, whereas in industrial and peri-urban areas it was primarily through root uptake and translocation of PTEs to rice grains, particularly for Cd and Pb. Source apportionment identified natural, industrial, and traffic as the three primary sources. The Bayesian mixing model revealed that the natural source contributed the highest proportion to rice grains (48.3–70.6%) across all four source areas. Except for natural sources, industrial sources dominated in industrial areas (29.1%), traffic emissions prevailed in roadside areas (19.4%), while mixed sources had the highest proportion in peri-urban areas (28.4%). Health risk assessment revealed that the total hazard index followed the order of peri-urban > industrial > roadside > rural areas, with rice ingestion being the dominant exposure pathway, accounting for over 90% of the total risk. The primary contributors to health risks were identified as As, Cd, and Pb, particularly in industrial and peri-urban areas. These findings provide a scientific basis for developing region-specific mitigation strategies tailored to the dominant contamination pathways in each area. Full article

Potentially toxic elements (PTE) pollution from lead–zinc (Pb–Zn) production poses significant ecological risks, requiring systematic assessment across the industrial chain. This study investigated soil, surface water, and sediments near a Pb–Zn mining area, integrating pollution indices (I_geo, NIPI, RI) with human health risk models. A spatial analysis framework was established by combining proportional symbol mapping and Thiessen polygons to analyze contamination patterns under small-sample conditions. Results showed a clear pollution hierarchy: smelting > beneficiation > tailings ≈ mining. Smelting and beneficiation zones exhibited multi-element pollution; Hazard Index (HI) exceedance probabilities reached 89% and 95%, respectively, while carcinogenic risk (CR) exceedance approached 100% across all zones. Cd was the dominant ecological risk factor, particularly in mining and tailings zones, where risk was mainly driven by a single element. Source apportionment identified two industrial groups—smelting-related (Pb, Hg, Zn, Se) and ore-associated (As, Cd, Cu, Sb)—whereas Cr, Ni, Co, and V were mainly derived from natural sources. These results indicate the need for coordinated management of beneficiation and smelting processes and provide a spatial analysis approach for small-sample assessment. Full article

Urban soil contamination by potentially toxic elements (PTEs) is a recognized health concern in densely populated urban environments. Through a systematic meta-analysis of 91 peer-reviewed studies (2000–2025) reporting 12,174 sampling sites in capital and core cities, we characterized regional patterns in the spatiotemporal dynamics and health risks of eight PTEs across two well-represented continental subsets (Asia, k = 18–36 per element; Europe, k = 11–23 per element) with comparative reference to the Americas, Africa, and Oceania. Given the uneven geographic distribution of qualifying primary studies, continental comparisons should be interpreted as hypothesis-generating: Asia (k = 18–36 per element) and Europe (k = 11–23 per element) provide the statistically robust core of the synthesis, while results for the Americas (k = 3–7 for several elements), Africa (k = 4–15), and Oceania (k = 2) are presented as illustrative rather than statistically representative. Pooled concentrations followed Zn (138.59) > Pb (56.97) > Cr (54.26) > Cu (47.00) > Ni (31.94) > As (8.56) > Hg (3.13) > Cd (1.23) mg·kg⁻¹. Within the well-represented Asian and European subsets, Asian cities showed the most severe enrichment of As, Cd, Cr, and Hg (I_geo > 4 in hotspots such as Kathmandu I_geo (Cd) = 7.06 and Jinan I_geo (Hg) = 5.27), whereas European centres exhibited substantial legacy Pb accumulation (pooled mean 87.69 mg·kg⁻¹). A reproducible pollution gradient was identified across functional zones: industrial > transportation ≥ residential > commercial > agricultural > urban green areas. The deterministic non-carcinogenic Hazard Index (HI = 1.49) for children in Asia exceeded the safe threshold (HI > 1), driven primarily by As and Cr exposure via incidental soil-and-dust ingestion. Monte Carlo probabilistic assessment (N = 10,000) confirmed elevated cumulative non-carcinogenic risk at the median of the exposure distribution for children in the data-rich Asian (P50 = 1.55; P(HI > 1) = 81.9%) and European (P50 = 1.28; P(HI > 1) = 69.8%) subsets, with adults in both subsets remaining well below the safety threshold (P(HI > 1) = 0.0%). Temporal analysis revealed a decoupling between economic growth and PTE accumulation in long-established cities, together with an inverse Ni–population correlation indicative of strategic resource allocation. For Asian capital and core cities, where the evidence base is strongest (k = 18–36 per element), the present synthesis supports further investigation of risk-based, child-centric soil management as a public-health priority. For European cities (k = 11–23 per element), the same direction of risk is indicated but should be confirmed in regionally focused syntheses. Policy considerations for under-represented regions should await expansion of the primary monitoring base. Full article

Environmental contamination by potentially toxic elements (PTEs) originating from industrial activities represents a major global challenge, necessitating the development of sustainable remediation strategies. While remediation of legacy (post-industrial) contamination has been relatively well studied, the remediation of ecosystems surrounding operating facilities subjected to increasing PTE loads remains insufficiently investigated. Therefore, the present study evaluated the efficacy of biochar derived from post-phytoremediation Miscanthus × giganteus (M×g) biomass to optimise the phytoremediation process using soil from an operating facility in a pot system. Valorisation of 29.0 kg of waste biomass yielded 12.8 kg of biochar (44.2%) with a high specific surface area (672 m² g⁻¹). Despite PTE enrichment during pyrolysis, the biochar was classified safe according to IBI thresholds. A pot experiment was conducted using contaminated and local background soils, amended with 3% (w/w) Miscanthus-derived biochar. Biochar application significantly improved plant performance in contaminated soil, increasing plant height, aboveground biomass, and root parameters by up to 208%, while restoring chlorophyll content and reducing stress indicators such as proline. Furthermore, biochar reduced PTE accumulation in plant tissues and supported the production of less contaminated biomass. These findings demonstrate that post-phytoremediation biomass-derived biochar enhances phytomanagement efficiency and supports sustainable biomass valorisation within a circular economy framework. Full article

Soil near urban areas may be burdened with numerous environmental pollutants including potentially toxic elements (PTEs). In this context, samples near the highway infrastructure in Larissa, Central Greece were examined for pseudo-total concentrations of Cr, Cu, Zn, Pb and Ni, and enrichment, ecological risk and human risk indices were calculated. Co-variation structure between PTEs and key soil properties was assessed through Principal Component Analysis (PCA). Screening for the pollution status of this area would quantify the possible risk, and therefore whether our subsequent rehabilitation trials would be of use. In this context, the most polluted sample was chosen to undergo a variety of remediation alternatives in a pot experiment, incorporating wheat and manure–attapulgite mixtures. Results showed enrichment of soil mainly with Ni, a low probability (9%) of risk exceedance for children for non-carcinogenic health effects and strong associations between the PTEs, indicating common sources. The greenhouse experiments showed that the application of manure–attapulgite reduced PTE concentrations in soil and wheat plant, with the greatest decrease observed for Pb, Cr and Ni. BCF values indicated strong accumulation of Ni (BCF > 1), while Cr and Cu showed limited uptake. Coefficient of contamination level (CCL) values (<1) for Cr and Cu confirmed reduced plant uptake, whereas Ni, Pb and Zn remained above 1. Taken together, the research shows that the fields chosen here are subjected to significant PTE input from lithogenic and anthropogenic sources, which may even become dangerous for sensitive sub-populations. Experimental cultivation of wheat shows that the combined amendments effectively reduced metal bioavailability and soil-to-plant transfer. Full article

Soil potentially toxic elements (PTEs) are crucial indicators of soil quality and ecological risk, especially in areas with complex pedogenesis and intensive anthropogenic activities. However, how soil development and land use jointly shape PTEs’ distribution across multiple scales remains unclear. A multi-scale framework encompassing catchment, sub-catchment, and regional scales was employed to examine the impacts of soil development and land use on PTEs’ (Cr, Ni, Cu, Zn, Pb, Cd, As, and Hg) distribution and their dominant drivers in the lower Yangtze River basin’s alluvial soils. Results showed significant scale-dependent variations in PTEs, with concentrations being highest on the regional scale. During pedogenesis, PTEs exhibited distinct evolutionary patterns across scales: Ni, Cu, Zn, and Cd decreased significantly at both the catchment and sub-catchment scales, whereas Cr, Ni, and As showed increasing trends at the regional scale. Land use also demonstrated scale-dependent effects, with drylands exhibiting PTEs’ enrichment at larger scales but significantly lower concentrations compared to woodlands and paddy-dryland rotation (paddies) at the regional scale. The mechanisms through which the Chemical Index of Alteration (CIA) influences PTE concentrations varied across scales, with metal oxide alteration as a key common pathway. Mantel tests showed that PTE distributions are governed by pH and total phosphorus (TP) at larger scales but by organic carbon (OC) and total nitrogen (TN) regionally. These cross-scale insights reveal how pedogenesis and human activity jointly shape HM patterns, highlighting the potential for scale-appropriate sustainable soil management—for instance, regionally tailored adjustments of pH and organic matter can mitigate metal risks while maintaining soil health. Future studies can build on this multi-scale framework by integrating long-term monitoring with predictive models to assess adaptive strategies under land-use change, thereby advancing sustainability in alluvial agroecosystems. Full article

Overexploitation of lead–zinc (Pb–Zn) mines results in rock exposure and the dispersal of potentially toxic elements (PTEs) via runoff. These potentially toxic elements accumulate in degraded depressions (negative landforms), leading to severe pollution and creating an urgent need for monitoring and remediation. Thus, this study focuses on a typical abandoned funnel–shaped Mississippi Valley–Type (MVT) Pb–Zn mine pit located in Maomaochang, northwestern Guizhou, China. A quadratic polynomial model was used to analyze the response of bryophyte diversity to vertical pollution gradients, and RLQ analysis was applied to explore the key species–trait–environment relationships. Results showed that PTE concentrations (e.g., Mn, Zn, Cd) in moss tissues converged with those in the soil. A total of 58 species from 22 genera in 6 families were identified, dominated by the families Pottiaceae, Bryaceae, and Brachytheciaceae. Both species and functional diversity exhibited a U–shaped response to an increase of the Nemerow composite index P_N (Z–score). Furthermore, a significant correlation was observed between PTEs and bryophyte distribution. Key bryophyte species showed distinct adaptations: in heavily polluted zones (e.g., pit bottom), Didymodon fallax (Hedw.) R. H. Zander displayed warted and curled leaves, whereas in lightly polluted zones (e.g., top), Plagiobryum zierii (Hedw.) Lindb. had smooth and flattened leaves. Overall, this study highlights that bryophytes possess potential bioindication capacity for environmental monitoring in this MVT Pb–Zn mine pit. Full article