Distribution Of Metals Research Articles

Spatial analysis of zinc (Zn) heavy metal distribution in the waters of Staring Bay, Southeast Sulawesi

Background: A spatial study of the distribution of heavy metal zinc (Zn) in the waters of Staring Bay, Southeast Sulawesi, has been conducted. This research aims to determine the spatial distribution of heavy metal Zn in the waters of Staring Bay. Methods: Sampling was carried out at 12 stations in the bay using a purposive sampling method. The concentration of heavy metal Zn in seawater samples was determined using an Atomic Absorption Spectrophotometer (AAS). Spatial analysis was performed using the Inverse Distance Weight (IDW) interpolation method (power = 2) with data processing software (ArcGIS 10.1). Findings: The results of the study indicate that the Zn metal concentration at the 12 research stations ranges from 0.0141 to 0.2085 ppm, with an average of 0.0668 ppm. The highest concentration of Zn metal is found at station 1. The results of the spatial analysis, with 12 stations, show that the area from the open sea to the coast of Tanjung Tiram Village has been contaminated with Zn heavy metal, ranging from 0.0132 to 0.2085 ppm. The same contamination is observed in the northern part of Wawosunggu Island, from the river mouth near Rumbia-rumbia Village to Lara Island, which has also been contaminated with a range of 0.0572 to 0.2085 ppm. Conclusion: Based on the contaminant factor (CF) values, the highest contamination by Zn metal occurs at station 1. Environmental variables (salinity, pH, temperature) show no significant effect on the concentration of Zn heavy metal. Novelty/Originality of this article: This study provides a comprehensive spatial analysis of zinc (Zn) contamination in Staring Bay, highlighting critical areas of pollution. It uniquely employs the Inverse Distance Weight interpolation method, revealing significant contamination patterns with minimal influence from environmental variables.

Exposure Levels, Health Risks, Spatially Distribution, Multivariate Statistics and Positive Matrix Factorization Model of Heavy Metals from Wild solid Waste Dumpsites

Exposure Levels, Health Risks, Spatially Distribution, Multivariate Statistics and Positive Matrix Factorization Model of Heavy Metals from Wild solid Waste Dumpsites

Support vector machine in the elementomic evaluation of arugula (Eruca Sativa) and lettuce (Lactuca sativa) grown in soils from a decommissioned mining area

Potentially toxic metals (PTMs) in plants are absorbed and accumulated in various parts of the plants. Due to the risk associated with consuming vegetables contaminated with PTMs, it is essential to determine the distribution of these metals in plants. Vegetables grown in soils contaminated by PTMs from a decommissioned manganese mine in Bahia, Brazil, were assessed for metal uptake and distribution. This study focused on Arugula (Eruca sativa) and lettuce (Lactuca sativa), chosen for their metal bioaccumulation properties and their role in the human diet. The metal concentration in the Arugula followed the order Fe > Mn > Cu > Cr > Tl > Co > Cd > Pb, while in lettuce, it was Mn > Fe > Cr > Tl > Co > Cu > Cd > Pb. A significant positive correlation between Mn and other metals suggests a common contamination source. The findings highlight a food safety risk from consuming these vegetables. Combining the PTMs bioaccumulation coefficient with Principal Component Analysis (PCA) and Support Vector Machines (SVM) effectively distinguished between plant types and parts, providing valuable insights into PTMs transfer from soil to the food chain

Hazard reduction of heavy metals by co-pyrolysis of modified vermiculite with paper mill sludge/municipal solid waste: Characterization, risk and reaction mechanism study in pyrolytic environment

The increasing volume of paper mill sludge (PM) and municipal solid waste (MW) poses environmental problems associated with heavy metals. Co-pyrolysis of PM/MW with additives effectively reduces the risk of heavy metal contamination. In this study, co-modified vermiculite (LMV) was prepared using the modification methods of intercalation-exfoliation, Mg2+ impregnation, and thermal activation. PM and MW were mixed at different doping ratios, and a non-doping experiment was performed to compare the pyrolysis processes and the retention rates for different heavy metals (Zn, Cr, Cu, Cd, and Pb), as well as the potential ecological risks, and the form distribution of the heavy metals. The addition of LMV reduced the risk posed by heavy metals. In the absence of doping, a higher pyrolysis temperature is conducive to an increase in the oxidizable and residual fractions of heavy metals without higher retention rates. Among these heavy metals, Zn, Cr, and Cu had higher retention rates and low risks, whereas Cd had a relatively high risk with low retention rates. Simulations showed that there was a transfer of the Mulliken charge after the reaction, indicating that all the heavy metals can interact with O, Al, and Si in the LMV; this reaction mainly occurs around the No. 17 O atom of the LMV. The monomers, oxides, and chlorides of Zn/Cr/Cu exhibited better adsorption on vermiculite compared to that of Pb/Cd.

Distribution, source apportionment and ecological risk assessment of heavy metals in Limbe River sediments, Atlantic Coast, Cameroon Volcanic Line

The objective of this research was to assess sediments contamination, provenance and metal pollution using single and complex pollution indicators. Limbe River sediment samples were analysed using Inductively Coupled Plasma—Mass Spectrometry. The Limbe River sediments exhibit high content in Fe2O3 sourced from haematization of basaltic rocks. The concentration of Cd, Co, Cr, Mn, Ni, Pb, Sn, Sr, V and Zn exceed upper continental crust and local baseline values for heavy metals. Correlation matrix analysis indicates the presence of common input sources and similar geochemical characteristics of heavy metals. Contamination factor (CF: 0.01–10.34), contamination degree (Cdeg: 14.91–36.57), pollution load index (PLI: 0.84–1.77), and nemerow integrated pollution index (NIPI: 0.2–1.7) indicates significant to high levels of contamination. The enrichment factor (EF: 0–5.67) and geo-accumulation index (Igeo: -7.55–2.59), suggests moderate to significant metal pollution of the Limbe River ecosystem, suggesting potential ecological effects. Modified hazard quotient (mHQ: 0.082–6.35) and toxic risk index (TRI: 10.49–27.43), indicates low to extreme pollution severity and high toxicity risks of heavy metals to the aquatic ecosystem fauna and flora. Primarily anthropogenic activities and secondary lithogenic provenance is attributed to sediments contamination and metals pollution. This study suggests that a greater emphasis should be placed on monitoring various provenances of metals entering the aquatic ecosystem from anthropogenic practices. The study emphasizes the significance of continual protection of aquatic ecosystem and biological resources and adaptive management. The development of reasonable goals for monitoring and remedial programmes can be aided by this data.

Habitat-specific allocations of elements in Atriplex lentiformis seeds indicate adaptation to metal toxicity.

Self-sustaining vegetation in metal-contaminated areas is essential for rebuilding ecological resilience and community stability in degraded lands. Metal-tolerant plants originating from contaminated post-mining areas may hold the key to successful plant establishment and growth. Yet, little is known about the impact of metal toxicity on reproductive strategies, metal accumulation, and allocation patterns at the seed stage. Our research focused on the metal tolerant Atriplex lentiformis. Specifically, we examined the effects of toxic metal(loid) concentration in soils on variability in its reproductive strategies, including germination patterns, elemental uptake, and allocation within the seeds. We employed advanced imaging techniques like synchrotron X-ray fluorescence microscopy (2D scans and 3D tomograms) combined with inductively coupled plasma mass spectrometry to reveal significant differences in metal(loid) concentration and distribution within the seed structures of A. lentiformis from contrasting habitats. Exclusive Zn hotspots of high concentrations were found in the seeds of the metallicolous accession, primarily in the sensitive tissues of shoot apical meristems and root zones of the seed embryos. Our findings offer novel insights into phenotypic variability and metal tolerance and accumulation in plants from extreme environments. This knowledge can be applied to enhance plant survival and performance in land restoration efforts.

The impact of organic carbon mineralization on pollution and toxicity of toxic metal in sediments: Yellow Sea and East China Sea study

Organic carbon mineralization is the main driving force of metal migration and transformation in sediments, greatly influencing the distribution, pollution degree, and toxicity of toxic metals. However, relevant research on this subject is still limited. In this study, the concentration of toxic metals (Cr, Cd, Cu, Pb, Zn, Co, Fe, Mn, Ni, As) in the solid and liquid phase (porewater) of sediments were measured, toxic metal pollution degree and toxicity of the Yellow Sea (YS) and the East China Sea (ECS) were assessed. Combined with the rate of organic carbon mineralization, the impact of organic carbon mineralization was analyzed. The results showed that Ni was slightly enriched and posed a certain ecological risk, and As was moderately enriched in the studied area, Pb was at a moderate pollution level in the studied area. Zn, Co, Mn, and Fe were at a moderate pollution level in the mud area of SYS and the west coastal area of ECS. Additionally, the total organic carbon mineralization rate (TCMR) in the ECS (5.12–18.04 mmol C m−2 d−1) was slightly higher than that in the YS (3.29–14.46 mmol C m−2 d−1) during spring. Moreover, organic carbon mineralization promotes metal enrichment, and the TCMR was significantly correlated with the pollution load index. Thus, TCMR can be used as an indicator to predict the degree of metal pollution. Furthermore, organic carbon mineralization promotes the mobilization of Cu from the solid phase to the liquid phase, while facilitating the transfer of Cr, Pb, Co, Ni, and Fe from the liquid phase to the solid phase. This process increases the potential risks of Cu and reduces the toxicity of Cr, Pb, Co, Ni, and Fe. Therefore, the impact of organic carbon mineralization should be considered in future assessments and predictions of toxic metal pollution and toxicity.

Heavy metals distribution and their ecological risk in the surface sediments of Haizhou Bay, China

A comprehensive analysis of heavy metal concentrations, sources, and pollution status was conducted on thirty surface sediment samples collected from Haizhou Bay, China in 2020. The spatial distributions of Cu, Pb, Zn, Cr, Cd, and total organic carbon (TOC) were found to be analogous. Noteworthy, sporadic pollution effects from Cu, Cr, and As were detected, although heavy metal concentrations remained below the probable effect level (PEL). A suite of analytical methods, including Pearson's correlation coefficient, geoaccumulation index, sediment quality guidelines, potential ecological risk index, and principal component analysis, was employed to elucidate the sources and assess the pollution risks. The results indicated that Hg emerged as the predominant heavy metal pollutant in Haizhou Bay sediments, with several stations showing high pollution levels that require attention. Other heavy metals were mainly of natural origin, indicating no significant pollution in the study area.

Metals Transfer in Mushroom Tricholoma matsutake from Regional High Geochemical Background Areas: Environmental Influences and Human Health Risk.

Wild-grown edible mushrooms are important in world diets and are also efficient metal accumulators. Yunnan, Southwest China, is the main producing region, with typically high levels of geochemical metals. The environmental factors, bioaccumulation, distribution and human health risks of metals were examined in paired soil and Tricholoma matsutake (n = 54). T. matsutake grows on acidified soils (pH = 3.95-6.56), and metals show a strong heterogeneity, with Fe, Mn, Zn and Cu in the ranges of 16-201, 0.046-8.58 g kg-1, and 22.6-215, 3.7-155 mg kg-1. High soil Fe content led to great accumulation in T. matsutake (0.24-18.8 g kg-1). However, though the soil Mn content was higher than that of Zn and Cu, their concentrations in T. matsutake were comparable (21.1-487 vs. 38.7-329 and 24.9-217 mg kg-1). This suggested that T. matsutake prefers to accumulate Zn and Cu compared to Mn, and this is supported by the bioaccumulation factors (BAFs = 0.32-17.1 vs. 0.006-1.69). Fe was mainly stored in stipes, while Mn, Zn and Cu were stored in caps, and the translocation factors (TFs) were 0.58 vs. 1.28-1.94. Therefore, stipe Fe showed the highest health risk index (HRI) at 1.28-26.9, followed by cap Cu (1.01-2.33), while 98-100% of the Mn and Zn were risk-free. The higher concentration and greater risk of Fe was attributed to the significant effect of soil Fe content (R = 0.34) and soil pH (R = -0.57). This study suggested that Fe, as an essential mineral, may exert toxic effects via the consumption of T. matsutake from high geochemical background areas.

Comprehensive evaluation of the distribution, transport and ecological risk of heavy metals in intra-urban river sediments using high-resolution techniques

Determining the distribution trends, transport mechanisms, and ecological risks of heavy metals (HMs) in urban river sediments is essential for the government to conduct appropriate remediation work. In this study, we collected sediment cores from the Yayao Waterway in Foshan City, China. The vertical distribution profiles of dissolved and labile Fe, Mn, Cd, Zn, Cu, Cr, Ni, Pb, As, and Co in the sediments were obtained using the thin-film diffusive gradient (DGT) and high-resolution peeper (HR-Peeper) techniques. In addition, the transport rates, contamination levels, and ecological concerns of the HMs were evaluated using the European Community Bureau of Reference (BCR) sequential extraction technique, the DGT-induced sediment fluxes (DIFS) model, and multiple contamination evaluation metrics. The results showed that most of the DGT-labile HMs were associated with Fe/Mn (hydrogen) oxides, and in particular, Zn, Ni, and Cr showed a significant negative correlation with Fe/Mn (p < 0.001). Additionally, Cd had the highest bioavailability (89.17%), and its net diffusive flux at the sediment–water interface (SWI) was positive, which indicated a high release risk from the sediment. However, the R-value of Cd based on the DGT-induced sediment fluxes (DIFS) operation was extremely low, suggesting that although Cd had the biggest supply pool of releases, its release rate was slow. The majority of sampling sites had significantly higher total HM contents in the surface sediments than the background values. The HM contamination in the sediments originated from human activities, primarily from industrial enterprises and with a large contribution from both agricultural and domestic sources. The most polluted HM with the highest ecological danger was Cd, followed by Cu, Zn, Ni, and As when the results of the four pollution evaluation indicators were combined. Consequently, the risk of contamination by HMs in inner-city river sediments should receive more attention.

Assessment and bioaccumulation of heavy metal contaminants in Golden Mahseer (Tor putitora Hamilton, 1822)

Unpolluted freshwater is a crucial component for maintaining the health of humans. This study aimed to investigate the bioaccumulation and potential health hazards of heavy metal contaminants (Fe, Cd, Cr, Cu, Pb) in water, sediments, and tissues of the golden mahseer fish (Tor putitora) from Zhob River to assess their suitability for human consumption. Samples (soil, water, and fish) were collected from the Zhob River, and Flame Atomic Absorption Spectrometry (FAAS) was employed to measure the concentration of these metals found in soil, water, and various fish body tissues (muscles, skin, gills, and liver). The overall results revealed that water quality parameters, i.e., temperature and pH were found within tolerable ranges, while electrical conductivity and turbidity exceeded the permissible limits of FAO/WHO for fish. Furthermore, this study also identified elevated concentrations of Pb in water and soil, as well as Fe and Cd in soil beyond the standards set by the World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA). In contrast, the concentrations of other targeted metals examined in fish body tissues were found below the permissible limits set by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), indicating the suitability of this fish species for human consumption. The estimated daily intake (EDI) of these targeted metals in various fish body tissues was found to be within the recommended dietary allowance (RDA), suggesting no associated health risks for the local population. Furthermore, both the Target Hazard Quotient (THQ) and Total Target Hazard Quotient (TTHQ) values measured in this study were less than one, indicating the absence of potential non-carcinogenic health risks related to the consumption of this riverine mahseer fish, but combined metal intake may pose potential health risks. Carcinogenic risk assessment for some metals like Cd, Cr, and Pb revealed no cancer risk for consumers. Moreover, our present research observed comparatively high bioaccumulation (BAF) of each targeted metal in the fish liver from both Zhob River water and soil as compared to other body tissues. Multivariate analysis, including the correlation matrix, revealed strong and significant correlations (P < 0.05) among heavy metal pairs (Fe/Cr, Fe/Pb, Cr/Fe, Cr/Pb, Pb/Fe, Pb/Cr). Hierarchical cluster analysis and Principal Component Analysis (PCA) were utilized to trace the origins of these metals, attributing their presence to nearby rock weathering, mining, as well as municipal and agricultural activities. These factors were recognized as potential sources of heavy metal bioaccumulation in riverine fish. Thus, our current study concluded that the Zhob River was contaminated with these heavy metals and emphasized the need to prevent domestic and industrial sewage inflow. The monitoring of these metals in the food chain was also underscored as crucial for reducing all kinds of associated health risks. This study provides the first report on heavy metal distribution in highly abundant and edible mahseer fishes of the Zhob River.

Distribution, ecological risk assessment, and source identification of potential toxic elements (PTEs) in Muttukadu backwater sediments, Southern India

Muttukadu Backwater is a robust estuary on the east coast of Tamil Nadu is contaminated by industrial, residential, and tourism-related activity (especially boat houses). In this present research, we investigated the heavy metal pollution, spatial distribution and statistical analysis of muttukadu coastal sediments, east coast of the Bay of Bengal in south India. In this study, we present the distribution of heavy metals in backwater sediments reveals enhanced levels of Fe, Mn, Cr, Zn, Cu, Ni, Pb, and Co and the highest concentrations of these metals are found at stations 2, 4, and 8. Based on contamination indices such as CD, Igeo, and PLI, moderate contamination is clear evident. However, the present data of Cr, Cu, and Pb metals have indicated low to moderate anthropogenic influence. We have identified the metals of Cr, Cu, and Pb indicated the High habitat risks are highlighted by ecological risk assessments, and it is due to the anthropogenic factors. Cu, Mn, Zn, and Cr are sourced from anthropogenic sources, while Pb, As, Co, and Ni originate from natural sources, according to spatial distribution analysis. A significant disturbance to the aquatic environment is caused by human activity. In this present study, underscores the necessity of pre-flooded dataset for future comparative research and ecological conservation in Muttukadu Backwater and their environments.

Assessment of seasonal variations in soil heavy metal concentrations and potential health risks in Gujarat, India.

This study investigates the prevalence, distribution, and ecological consequences of 21 heavy metals (Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, Pb, Sr, and Zn) in the soils between the Mahi and Dhadhar rivers in Gujarat, India. It aims to assess the seasonal variations in soil contamination and the potential human health risk associated with the heavy metal exposure through ingestion, inhalation, and dermal contact pathways. Soil samples were collected from 57 sites across three distinct seasons and analyzed using indices such as the geo-accumulation index, contamination factor, pollution load index, ecological risk factor, and global potential ecological risk. Human health risks were also evaluated for carcinogenic and non-carcinogenic effects. The findings reveal significant soil contamination, especially during the Monsoon and Post-Monsoon seasons, with heavy metals like Ag, Cd, Cr, Cu, Co, Ni, and Pb posing considerable ecological threats. Cr and Ni were identified as presenting the highest carcinogenic risks, while Fe and Cr posed major non-carcinogenic challenges. Seasonal variations significantly influenced heavy metal concentrations and distribution patterns. The study highlights the urgent need for comprehensive policies and sustainable practices to mitigate soil contamination and protect environmental health. It emphasizes the critical role of human activities, such as industrial, agricultural, and mining operations, in soil degradation and calls for increased community awareness and action to address these challenges.

The role of soil elemental forms in the soil-plant migration system: An example of heavy metals in Epimedium production areas

Investigating the heavy metal content and migration behavior in the soil and plant system of Epimedium origin is crucial for ensuring the safety and sustainable development of this valuable medicinal plant. The concentration of heavy metals in the soil of Epimedium was found to be highest in the residuel form (RS) and lowest in the water-soluble form (WS). Among the different parts of the Epimedium plant, leaves showed the highest content of Cr, Ni, Cu, As, and Pb with average contents of 0.02 mg.kg−1, 0.01 mg.kg−1, 0.11 mg.kg−1, 0.16 mg.kg−1, and 0.01 mg.kg−1, respectively, and roots showed the highest content of Zn with average contents of 0.30 mg.kg−1. The results of correlation analysis and linear fitting showed significant correlation and better linear fitting results between different parts of Epimedium (roots, stems and leaves) and various forms of heavy metals in soil. Among them, Zn (ion-exchange form) and Zn (leaf) showed the best fit with R2 reaching 0.74. Results from random forest modeling indicated that the forms of heavy metals in soil, such as bound form, ion exchange form, and strong organic bound form, significantly influenced the distribution of heavy metals in roots, stems, and leaves of Epimedium. Overall, besides the readily available heavy metals in soil, other forms of heavy metals also play a critical role in the soil-plant migration system.

Microstrain screening towards defect-less layered transition metal oxide cathodes.

Microstrain and the associated surface-to-bulk propagation of structural defects are known to be major roadblocks to developing high-energy and long-life batteries. However, the origin and effects of microstrain during the synthesis of battery materials remain largely unknown. Here we perform microstrain screening during real-time and realistic synthesis of sodium layered oxide cathodes. Evidence gathered from multiscale in situ synchrotron X-ray diffraction and microscopy characterization collectively reveals that the spatial distribution of transition metals within individual precursor particles strongly governs the nanoscale phase transformation, local charge heterogeneity and accumulation of microstrain during synthesis. This unexpected dominance of transition metals results in a counterintuitive outward propagation of defect nucleation and growth. These insights direct a more rational synthesis route to reduce the microstrain and crystallographic defects within the bulk lattice, leading to significantly improved structural stability. The present work on microstrain screening represents a critical step towards synthesis-by-design of defect-less battery materials.

Blood metal concentrations and cardiac structure and function in total joint arthroplasty patients.

There is concern regarding potential long-term cardiotoxicity with systemic distribution of metals in total joint arthroplasty (TJA) patients. To determine the association of commonly used implant metals with echocardiographic measures in TJA patients. The study comprised 110 TJA patients who had a recent history of high chromium, cobalt or titanium concentrations. Patients underwent two-dimensional, three-dimensional, Doppler and speckle-strain transthoracic echocardiography and a blood draw to measure metal concentrations. Age and sex-adjusted linear and logistic regression models were used to examine the association of metal concentrations (exposure) with echocardiographic measures (outcome). Higher cobalt concentrations were associated with increased left ventricular end-diastolic volume (estimate 5.09; 95%CI: 0.02-10.17) as well as left atrial and right ventricular dilation, particularly in men but no changes in cardiac function. Higher titanium concentrations were associated with a reduction in left ventricle global longitudinal strain (estimate 0.38; 95%CI: 0.70 to 0.06) and cardiac index (estimate 0.08; 95%CI, -0.15 to -0.01). Elevated cobalt and titanium concentrations may be associated with structural and functional cardiac changes in some patients. Longitudinal studies are warranted to better understand the systemic effects of metals in TJA patients.

Contrasting metal bioaccumulation in marine benthic invertebrate groups in polluted harbor sediments

This study examined the sediment metal fractions and availability to infer bioaccumulation in marine harbor benthic organisms. Total metals were analyzed using atomic absorption spectrometry and inductively coupled plasma-optical emission spectrometry for chemical fractions and organisms. The results showed similar metal concentrations and distribution driven by rivers and harbor pollution. We found significant differences in metal accumulation in marine benthic groups, highest in scavenger species. Their metal concentrations in decreasing order were 1.97–4568, 0.10–1260, 1.64–159, and 0.105–112 μg g−1 dw for hermit crabs, forams, bivalves, and polychaetes. Moreover, certain organisms, such as tusk shells, sea pens, bivalves, forams, and isopods, may exhibit selective metal accumulation. Biota-sediment accumulation factors (>1) were highest for essential metals like Cu, Zn, and Mn, while toxic metals like As, Cr, Co, and Ni increased. This concurrent assessment provides more comprehensive data for metal bioaccumulation in marine benthic ecosystems.

Distribution and geochemical speciation of metals in the sediments of marine aquaculture areas in Japan.

Metal contamination is a crucial environmental issue because of its persistence and toxicity, which can have deleterious effects on aquatic ecosystems. Coastal sediments serve as reservoirs for metals. Aquaculture is an important human activity in coastal areas; however, the actual status of metal distribution in these areas has not been well characterized. We investigated the distribution and geochemical speciation of metals in the sediments of the Japanese aquaculture areas of Shidugawa and Furue Bays. Total metals were generally in the order Zn > Cu > Ni > Cd > Pb and occurred at high levels at the sites in the inner parts and near the fish cages in the sampling areas. Pearson's correlations and principal component analysis results suggested that the metals in these aquaculture areas might originate from several sources, such as fish feces, fish feeds, corrosion of antifouling material residues, and local anthropogenic activities, including fertilizers and manures. Furthermore, metals were mainly in silts and fine sediments, associated with residual speciation, followed by organic fractions, oxides, and high fractions of exchangeable Cd. These results provide important insights into the accumulation of metals in sediments for better managing marine aquaculture in Japan.

Morphological Enrichment and Environmental Factors Correlation of Heavy Metals in Dominant Plants in Typical Manganese Ore Areas in Guizhou, China.

Bioavailable heavy metal and their efficient phytoremediation in mining areas have major implications for environmental and human health. In this study, we investigated 12 dominant plants in a typical Mn ore area of Zunyi, Guizhou Province, China, to determine the heavy metal contents, morphologies, and environmental factors affecting Mn, Cd, Pb, Cu, Zn, and Cr in the plant parts and rhizosphere soil. The bioavailabilities and degrees of metals were evaluated using the ratios of the secondary to primary phase distributions and potential ecological risk indices. Principal component analysis, cluster analysis, positive matrix factorisation modelling, and redundancy analysis were used to trace the origins and correlations among the metals. The results indicate that the bioavailabilities were the highest for Mn and Cd in the study area, and all of the target heavy metals had bioavailabilities above the moderate ecological harm level. Statistical modelling indicates that there are four main pollution sources: mining, smelting, processing operations, and atmospheric deposition. The dominant plants had high heavy metal enrichments, bioconcentration factors, and translocation factors for Mn, Cu, Cr, Cd, and Zn. The redundancy analysis indicates that soil total N, total P, and pH affect metal absorption and distributions in Compositae and non-Compositae plants in low-N, low-P, and slightly alkaline mining environments. This study provides a feasible basis for the screening of heavy metal enrichment plants and the improvement of remediation technology in manganese ore area under the extreme environment of poor nutrition.

Phytotoxic responses of acrocarpous moss Campylopus schmidii as bioindicators in copper and cadmium contaminated environments: A comprehensive assessment

Mosses play a vital role in environmental research as reliable biomonitoring tools. This study aims to understand the accumulation and distribution patterns of Cu and Cd in the acrocarpous moss [Campylopus schmidii (Müll. Hal.) A. Jaeger] (C.schmidii). In controlled in vitro experiments, C.schmidii cultures were exposed to varying concentrations of copper (Cu) and cadmium (Cd) stress (0, 10, 25, 50 μmol/L) in aquatic media. The study systematically evaluated the moss's response, including observing appearance features, oxidative traits, and accumulation characteristics. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analyses were employed. They aimed to characterize and determine the distribution of metal particles in different parts of the mosses under high concentration treatments (50 μmol/L Cd, 50 μmol/L Cu, 50 μmol/L Cu and Cd). Results indicated that C.schmidii exhibited greater tolerance to Cu compared to Cd, as evidenced by significantly higher soluble protein content and lipid peroxidation with increasing concentrations. However, Cd stress induced severe damage, including widespread chlorosis, reduced chlorophyll content, and surface fragmentation. Both Cu and Cd were found to stimulate antioxidant levels by increasing the activity of hydrogen peroxide and peroxidase, thus reducing the accumulation of free radicals in C.schmidii. Additionally, the results revealed differential metal distribution. Higher Cu (2.23%) and lower Cd (0.54%) accumulation were observed at the bottom of gametophores, with Cd content 180.46% higher than Cu at the top. This study provides valuable insights into the potential application of acrocarpous mosses for biomonitoring and phytoremediation. It suggests specific strategies for metal deposition and absorption, such as utilizing upper, younger parts for Cd absorption and lower parts for Cu remediation in soil.