Search Results (355)

Soil environmental quality in arid oases is crucial for regional ecological security but faces multi-source heavy metal (HM) contamination risks. This study aimed to (1) characterize the spatial distribution of soil HMs (As, Cd, Cr, Cu, Hg, and Zn) in the Ka Shi gar oasis, Xinjiang, (2) quantify the driving effect of irrigation water, and (3) elucidate interactions between HMs, soil properties, and land use types. Using 591 soil and 12 irrigation water samples, spatial patterns were mapped via inverse distance weighting interpolation, with drivers and interactions analyzed through correlation and land use comparisons. Results revealed significant spatial heterogeneity in HMs with no consistent regional trend: As peaked in arable land (5.27–40.20 μg/g) influenced by parent material and agriculture, Cd posed high ecological risk in gardens (max 0.29 μg/g), and Zn reached exceptional levels (412.00 μg/g) in gardens linked to industry/fertilizers. Irrigation water impacts were HM-specific: water contributed to soil As enrichment, whereas high water Cr did not elevate soil Cr (indicating industrial dominance), and Cd/Cu showed no significant link. Interactions with soil properties were regulated by land use: in arable land, As correlated positively with EC/TN and negatively with pH; in gardens, HMs generally decreased with pH, enhancing mobility risk; in forests, SOM adsorption immobilized HMs; in construction land, Hg correlated with SOM/TP, suggesting industrial-organic synergy. This study advances understanding by demonstrating that HM enrichment arises from natural and anthropogenic factors, with the spatial heterogeneity of irrigation water’s driving effect critically regulated by land use type, providing a spatially explicit basis for targeted pollution control and sustainable oasis management. Full article

The high pH and heavy metal leaching of argon oxygen decarburization (AOD) slag limit its application in agriculture. Slag carbonation can aid in decreasing slag alkalinity and inhibit heavy metal release; the environmental safety of utilizing carbonated AOD slag (CAS) as a fertilizer remains a topic of significant debate, however. In this work, pakchoi (Brassica chinensis L.) was planted in CAS-fertilized soil to investigate the accumulation and migration behavior of heavy metals in the soil–plant system and perform an associated risk assessment. Our results demonstrated that CAS addition increases Ca, Si, and Cr concentrations but decreases Mg and Fe concentrations in soil leachates. Low rates (0.25–1%) of CAS fertilization facilitate the growth of pakchoi, resulting in the absence of soil contamination and posing no threat to human health. At the optimal slag addition rate of 0.25%, the pakchoi leaf biomass, stem biomass, leaf area, and seedling height increased by 34.2%, 17.2%, 26.3%, and 8.7%, respectively. The accumulation of heavy metals results in diverging characteristics in pakchoi. Cr primarily accumulates in the roots; in comparison, Pb, Cd, Ni, and Hg preferentially accumulate in the leaves. The migration rate of the investigated heavy metals from the soil to pakchoi follows the order of Cr > Cd > Hg > Ni > Pb; in comparison, that from the roots to the leaves follows the order Cd > Ni > Hg > Cr > Pb. Appropriate utilization of CAS as a mineral fertilizer can aid in improving pakchoi yield, achieving sustainable economic benefits, and preventing environmental pollution. Full article

Mercury (Hg) poses a significant threat to human health and ecosystems, garnering increased attention in environmental studies. This paper evaluates the dynamics of Hg accumulation in various common tree leaves, specifically white poplar, linden, and cherry plum, throughout their growing season. The findings offer valuable insights into air quality and the ability of urban vegetation to mitigate mercury pollution in urban areas. A case study was conducted in Turda, a town in northwestern Romania, where a former chlor-alkali plant operated throughout the last century. Although the plant ceased its electrolysis activities over 25 years ago, the surrounding soil remains contaminated with mercury (Hg) due to the significant amounts released during its operation. The results indicated that the Hg concentration varied between 2.4 and 7.3 mg kg⁻¹ dry weight (dw), exceeding the intervention threshold for soil of 2.0 mg kg⁻¹. Additionally, the Hg content in the leaf samples consistently increased over time, influenced by leaf age and tree species. The Hg content increased in the following order: cherry plum < white poplar < linden. On average, white poplar leaves accumulated 72 ng Hg g⁻¹ dw, linden leaves 128 ng Hg g⁻¹ dw, and cherry plum leaves 47 ng Hg g⁻¹ dw during the six-month monitored period from April to September. The results obtained can be used to evaluate the potential of different tree species for mitigating atmospheric Hg contamination and to elaborate on the suitable management of fallen leaves in the autumn. Full article

Heavy metal pollution due to mining activities poses a significant threat to agricultural production, ecosystem health, and food security in South Africa. This review integrates current knowledge on the use of mustard spinach (Brassica juncea (L.) Czern.) for the bioremediation of polluted water and soil, focusing on enhancing phytoremediation efficiency through the use of silicon-based biostimulant treatments. Mustard spinach is known for its capacity to accumulate and tolerate high levels of toxic metals, such as Pb, Cd, and Hg, owing to its strong physiological and biochemical defense mechanisms, including metal chelation, antioxidant activity, and osmotic adjustment. However, phytoremediation potential is often constrained by the negative impact of heavy metal stress on plant growth. Recent studies have shown that silicon-based biostimulants can alleviate metal toxicity by reducing metal bioavailability, increasing metal immobilization, and improving the antioxidative capacity and growth of plants. Combining silicon amendments with mustard spinach cultivation is a promising, eco-friendly approach to the remediation of mining-impacted soils and waters, potentially restoring agricultural productivity and reducing health risks to the resident populations. This review elucidates the multifaceted mechanisms by which silicon-enhanced phytoremediation operates, including soil chemistry modification, metal sequestration, antioxidant defense, and physiological resilience, while highlighting the practical, field-applicable benefits of this combined approach. Furthermore, it identifies urgent research priorities, such as field validation and the optimization of silicon application methods. Full article

During the past decades, agricultural soil heavy metal pollution has been becoming increasingly severe due to urbanization and industrialization. However, the impact of externally input heavy metals on deep soils remains unclear because most previous relevant research only focused on surface soils. In the present study, Concentrations of eight heavy metals (Cu, Zn, Ni, Pb, Cr, Cd, As, and Hg) were determined for 72 pairs of surface and deep soil samples collected from an agricultural region close to the Pearl River estuary. Subsequently, heavy metal pollution and potential health risks were assessed using the Geo-accumulation Index and Potential Ecological Risk Index, a dose response model and Monte Carlo simulation, respectively. Principal component analysis (PCA) and the positive matrix factorization (PMF) receptor model were combined to analyze heavy metal sources. The results indicated that average concentrations of all heavy metals exceeded their corresponding background values. Cd was identified as the main pollutant due to its extremely high values of I_geo and Er. Unacceptable potential heavy metal non-carcinogenic and carcinogenic risks indicated by respectively calculated HI and TCR, higher than thresholds 1.0 and 1.0 × 10⁻⁴, mainly arose from heavy metals As, Cd, Cr, and Ni through food ingestion and dermal absorption. Anthropogenic sources respectively contributed 19.7% and 38.9% for soil As and accounted for the main contributions to Cd, Cu, and Hg (Surface: 90.2%, 65.4%, 67.3%; Deep: 53.8%, 54.6%, 56.2%) within surface and deep layers. These results indicate that soil heavy metal contents with deep layers were also significantly influenced by anthropogenic input. Therefore, we suggest that both surface and deep soils should be investigated simultaneously to gain relatively accurate results for soil heavy metal pollution and source apportionments. Full article

Identifying the soil quality and the sources of heavy metals in the production areas of characteristic agricultural products is crucial for ensuring the quality of such products and the sustainable development of agriculture. This research took the farmland soil of Luzuo Town, a characteristic production area of Cangshan garlic in Linyi City, as the research object. The contents of Cr, Cu, Ni, Pb, Zn, As, Hg, and Cd in farmland soil were analyzed. The ecological risks were evaluated using the Geographical Cumulative Index (I_geo) and the Potential Ecological Risk Index. The spatial distribution characteristics of the elements were determined through geostatistical analysis, and Positive Matrix Factorization (PMF) was used for source apportionment. The results show the following: (1) The average concentrations of all heavy metals exceeded local background values, with Cr and Hg surpassing the screening thresholds from China’s “Soil Pollution Risk Control Standards” (GB 15618-2018). (2) The results of the Moran’s index show that, except for Hg and Cd, all the elements had a high spatial autocorrelation, and there are two potential highly polluted areas in the study area. (3) Soils were generally uncontaminated or low risk, with Hg and Cd as the primary ecological risk contributors. (4) Five sources were quantified: fertilizer and pesticide sources (32.28%); mixed sources of fertilizer, pesticides, and manure (14.15%); mixed sources of traffic activities and agricultural waste discharge (19.95%); natural sources (20.55%); and incineration sources (13.07%). This study demonstrates the value of integrating geospatial and statistical methods for soil pollution management. Targeted control of Hg/Cd and reduced agrochemical use are recommended to protect this important agricultural region. Full article

This study assessed heavy metal contamination and associated health risks in soils and crops in the vicinity of a mercury mine located in Tongren, Guizhou Province, China, focusing on mercury (Hg), cadmium (Cd), arsenic (As), lead (Pb), and chromium (Cr). The study used the Index of Geological Accumulation (Igeo) and Health Risk Assessment (HRA) to quantify the level of contamination and assess the potential risks. The results showed that Area I was the most severely contaminated, with 94.24% of the sample sites being heavily contaminated with mercury, followed by Area II and Area III with severe cadmium contamination. The health risk assessment showed that children were exposed to non-carcinogenic risks of mercury and cadmium that exceeded the safety thresholds, with mercury being the major non-carcinogenic factor, especially through oral intake. The study also assessed the contribution of each heavy metal to pollution, with mercury contributing the most to ecological and health risks, especially in Areas I and III. The study highlights the urgent need to strengthen pollution control strategies, focusing on mining activities and agricultural inputs, to reduce risks and protect public health. Full article

Due to high geological background and intensive mining activities, soils are prone to heavy metals (HMs) accumulation and ecological fragility in Guizhou Province, China. A total of 740 topsoil samples were therefore collected, and aimed to determine the concentrations of As, Cd, Cr, Hg, and Pb, estimate the ecological pollution, and evaluate the carcinogenic and non-carcinogenic health risks to humans. Results showed As (1.08%) and Cd (24.46%) in soil exceeded standards. The Igeo showed that Cr (1.49%) and Hg (31.62%) in soil were at light pollution levels; single factor pollution index (PI) showed that Cd (21.35%) in soil was mildly polluted; risk index (RI) as at a low risk level. Notably, both deterministic and Monte Carlo analyses revealed unacceptable carcinogenic risks for As and Cr in children, with traditional methods potentially underestimating As risks. Moreover, Target-Organ Toxicity Dose (TTD) revealed soil HMs as a higher risk to hematological health, with notable health risks posed by Pb in children. It is noted that spatial distribution analysis suggested that the southwestern region of Guizhou Province should be prioritized for health risk management and control. By integrating the uniqueness of geological environments, multi-dimensional health risk assessments, and spatial distributions, the present study provides a scientific basis for assessing HMs pollution risks and soil health risks in the karst regions. Full article

In recent years, land degradation has become a major challenge for human society, with negative impacts on the natural habitat, the economy, and human well-being. A variety of anthropogenic and natural factors are exacerbating the processes of land degradation in the era of climate change. Land restoration is an important and proactive strategy to combat this negative situation. Among the many approaches, the use of vegetation plays a central role in restoring soil health, preventing erosion, promoting biodiversity, and improving water retention. Therefore, the identification of new plant species that have the properties to contribute to land restoration is a necessity today. The plant proposed in this conceptual review for land restoration is the cup plant (Silphium perfoliatum L.). After a brief presentation of the agronomy, adaptability, and multiple uses of this plant species, its potential to provide important ecosystem services useful for land restoration to combat land degradation is herein emphasized. Recent studies have shown that this plant has great potential for phytoremediation of soils contaminated with heavy metals (Zn, Pb, Cr, Cd, Ni, Hg, and Co), especially in post-mining areas where pollution exceeds ecological limits. Most studies have shown that the accumulation of heavy metals is higher at the lamina stage. There is also some evidence that the cup plant thrives in flood-prone areas and contributes to their restoration. Cup plant cultivation can also reduce greenhouse gasses and increase the organic carbon content of the soil. Another method of land restoration related to the establishment of the cup plant in a given area is the suppression of weeds, particularly the prevention of the invasion of exotic weed species. Further research under different soil–climatic conditions is needed to investigate cup plant cultivation as a promising strategy for land restoration in a time when the climate is constantly changing. Full article

Active and abandoned mining sites are significant sources of heavy metals and metalloid pollution, leading to serious environmental issues. This study assessed the environmental risks posed by potentially toxic elements (PTEs), specifically arsenic (As) and antimony (Sb), in the Technosols (mining residues) of the former Pejão coal mine complex in Northern Portugal, a site impacted by forest wildfires in October 2017 that triggered underground combustion within the waste heaps. Our methodology involved determining the “pseudo-total” concentrations of As and Sb in the collected heap samples using microwave digestion with aqua regia (ISO 12914), followed by analysis using hydride generation-atomic absorption spectroscopy (HG-AAS). The concentrations of As an Sb ranging from 31.0 to 68.6 mg kg⁻¹ and 4.8 to 8.3 mg kg⁻¹, respectively, were found to be above the European background values reported in project FOREGS (11.6 mg kg⁻¹ for As and 1.04 mg kg⁻¹ for Sb) and Portuguese Environment Agency (APA) reference values for agricultural soils (11 mg kg⁻¹ for As and 7.5 mg kg⁻¹ for Sb), indicating significant enrichment of these PTEs. Based on average I_geo values, As contamination overall was classified as “unpolluted to moderately polluted” while Sb contamination was classified as “moderately polluted” in the waste pile samples and “unpolluted to moderately polluted” in the downhill soil samples. However, total PTE content alone is insufficient for a comprehensive environmental risk assessment. Therefore, further studies on As and Sb fractionation and speciation were conducted using the Shiowatana sequential extraction procedure (SEP). The results showed that As and Sb levels in the more mobile fractions were not significant. This suggests that the enrichment in the burned (BCW) and unburned (UCW) coal waste areas of the mine is likely due to the stockpiling of lithic fragments, primarily coals hosting arsenian pyrites and stibnite which largely traps these elements within its crystalline structure. The observed enrichment in downhill soils (DS) is attributed to mechanical weathering, rock fragment erosion, and transport processes. Given the strong association of these elements with solid phases, the risk of leaching into surface waters and aquifers is considered low. This work underscores the importance of a holistic approach to environmental risk assessment at former mining sites, contributing to the development of sustainable remediation strategies for long-term environmental protection. Full article

Yuexi County, a key tea-producing area in eastern Dabie Mountain, may face potential heavy metal(oid) (HM) contamination risks due to nearby mining and intensive agricultural activities. This study investigated seven HMs (As, Cd, Cr, Hg, Ni, Pb, and Zn) in paired soil–tea samples using multiple analytical approaches, including the geoaccumulation index (I_geo), the potential ecological risk index (RI), bioconcentration factor (BCF), and positive matrix factorization (PMF) with Monte Carlo simulation for health risk assessment. Results showed that Zn (82.65 mg/kg) and Cd (0.15 mg/kg) were the most enriched HMs in soils with higher I_geo values than other HMs. PMF analysis identified four major HM sources: mining and transportation (27.75%), agricultural activities (26.90%), natural soil parent material (26.17%), and industrial emissions (19.18%). Tea plants exhibited selective HM absorption, with Hg showing the highest bioaccumulation (BCF = 0.45), while As, Cr, and Pb had minimal uptake (BCF < 0.05). Although health risk assessments confirmed that both non-carcinogenic and carcinogenic risks from soil and tea consumption were within safe limits for adults and children, Cr and Ni required special attention due to their risk contributions. Overall, ecological and health risks in the region were found to be low. These findings provide important scientific support for pollution monitoring, risk management, and overcoming trade barriers in tea-growing regions with acidic soils. Future research should integrate HM speciation analysis with seasonal monitoring to further optimize tea plantation management strategies. Full article

Systematic assessment of heavy metal contamination in agricultural soils is critical for addressing ecological and public health risks in industrial-intensive cities like Lanzhou, with direct implications for achieving UN Sustainable Development Goals (SDGs) 2 (Zero Hunger), 15 (Life on Land), and 3 (Good Health). The present study evaluates farmland soils around six industrial sectors: waste disposal (WDZ), pharmaceutical manufacturing (PMZ), chemical manufacturing (CMZ), petrochemical industry (PIZ), metal smelting (MSZ), mining (MZ) and one sewage-irrigated zone (SIZ) using geo-accumulation index, Nemerow composite pollution index, potential ecological risk index, and health risk models. The following are the major findings: (1) SIZ and PMZ emerged as primary contamination clusters, with Hg (I_geo = 1.89) and Cd (I_geo = 0.61) showing marked accumulation. Chronic wastewater irrigation caused severe Hg contamination (0.97 mg·kg⁻¹) in SIZ, where 100% of the samples reached strong polluted levels according to the Nemerow composite pollution index; (2) Hg and Cd dominated the ecological risks, with 41.32% of the samples exhibiting critical Hg risks (100% in PMZ and SIZ) and 32.63% showing strong Cd risks; and (3) oral ingestion constituted the dominant exposure pathway. Children faced carcinogenic risks (CR = 1.33 × 10⁻⁴) exceeding safety thresholds, while adult risks remained acceptable. Notably, high Hg and Cd levels did not translate to proportionally higher health risks due to differential toxicological parameters. The study recommends prioritizing Hg and Cd control in PMZ and SIZ, with targeted exposure prevention measures for children. Full article

Mercury (Hg) contamination in soils poses significant environmental risks. In response, various nature-based solutions (NbSs) have been developed and studied in the past to treat mercury along with other heavy metals from both point and nonpoint sources. However, various land uses present uncertainties in mercury mobility and treatment efficiency, affecting the scalability of NbS systems. In this study, a systematic review of peer-reviewed articles addressing mercury pollution in NbS soils was conducted. Results revealed that lakeside environments and mining areas are key Hg accumulation zones due to hydrological connectivity and anthropogenic pressures. Constructed wetlands were the most studied NbSs, where those with Acorus calamus and Aquarius palifolius as the main vegetation achieved >90% Hg removal efficiencies. Although NbSs achieved high Hg removal, anaerobic conditions were found to promote MeHg formation, a critical drawback. Moreover, biochar demonstrated potential for immobilizing Hg and reducing bioavailability, though certain types increased MeHg formation under specific redox conditions. Overall, the study highlighted the need for site-specific design, long-term field evaluation, and multidisciplinary strategies to optimize NbS performance for mercury removal. Furthermore, future research on the scalability of mercury-treating NbSs across diverse land uses is recommended to address mercury risks and improve effectiveness. Full article

(1) Background: Road traffic emissions significantly influence heavy metal accumulation in roadside agricultural soils, posing risks to food safety. (2) Methods: This study investigated the concentrations of heavy metals (As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn) in paddy soils at 96 soil samples along National Highways G107 and G312 in southern Henan, China, to evaluate the contamination situation and ecological risks using a multimetric approach. (3) Results: Cd, Hg, Cu, and Zn exceeded provincial background levels. Cd dominated contamination, showing heavy pollution (single factor index, P_i > 5) within 40 m of G107 and moderate/heavy levels (P_i = 2–5) along G312. The Nemerow index (P_N) classified both highways as slightly polluted (P_N = 0.70–0.81), with higher contamination along G107. Geoaccumulation indices identified Cd as mildly/moderately polluted within 40 m of G107 and G312 and Zn as slightly contaminated within 20–40 m of G107. Despite low total ecological risk, Cd contributed >75% to cumulative risk due to its high toxicity (Tr = 30). (4) Conclusions: Road traffic constitutes one of the contributors to heavy metal accumulation in paddy soils along national highways in southern Henan Province, while agricultural cultivation adjacent to transportation corridors poses potential food safety risks. Full article

Mineral elements can either be pollutants or essential dietary components. Monitoring their levels in the environment and living organisms is crucial because excessive amounts can become toxic. Dogs, due to their proximity to humans, shared habitats, and similar organ structures, can be effective indicators of environmental pollution by toxic elements. This study aimed to assess the levels of 11 mineral elements in 80 dog carcasses (49 males and 31 females), aged between 2 and 16 years, from the Ionian-Etnean volcanic region of the province of Catania, where the dogs had died under unknown circumstances. A direct mercury analyzer (DMA-80) was used to measure Hg, and an inductively coupled plasma mass spectrometer (ICP-MS) was used for the other elements. A one-way ANOVA, followed by Bonferroni’s multiple comparison for post hoc analysis, was conducted to evaluate significant differences between the organ samples and different minerals and between the weight and metal levels. The statistical significance was set at p < 0.05. The study indicates that high concentrations of metals like cadmium, mercury, lead, and chromium are present in the liver, kidneys, and other organs. These elevated concentrations suggest that the local volcanic emissions contribute to soil, water, and atmospheric contamination. The data showed differences in the metal concentrations between the sexes, which could be attributed to biological and environmental factors. Full article