Distribution Of Metals Research Articles

Occurrence, distribution, and ecological risk of heavy metals using species sensitivity distribution model in Pangkajene river, Indonesia

Occurrence, distribution, and ecological risk of heavy metals using species sensitivity distribution model in Pangkajene river, Indonesia

Speciation distribution and leaching behavior of heavy metals in coal gasification fine ash: Influence of particle size, carbon content and mineral composition

In this study, the occurrence and distribution of heavy metals in coal gasification fine ash (CGFA) with different particle sizes were investigated to ensure safer disposal and utilization strategies for CGFA. These measures are critical to sustainable industrial practices. This study investigates the distribution and leachability of heavy metals in CGFA, analyzing how these factors vary with particle size, carbon content, and mineral composition. The results demonstrated that larger CGFA particles (>1 mm) encapsulated up to 70 % more heavy metals than smaller particles (<0.1 mm). Cr and Zn were present in higher concentrations in larger CGFA particles, whereas volatile elements such as Zn, Hg, Se, and Pb were found in relatively higher contents in finer CGFA particles. At least 70 % of Hg in CGFA was present in an acid-soluble form of speciation, whereas Cd, Zn, and Pb were mostly present in a reducible form of speciation, which could be attributed to the presence of franklinite. More than 40 % of Cd and Zn in fine CGFA particles exist in an acid-soluble form. With the exception of CGFA_1.18, Se in CGFA mainly existed in an oxidizable form at a ratio of 60 %–80 %. This could be attributed to the presence of bassanite particles as well as the higher affinity of Se for S. In contrast, Cr, Cu, and As were mostly present in residual speciation forms owing to their parasitism in quartz, sillimanite, and amorphous Fe solid solution in CGFA. Additionally, the study revealed that there was no significant relationship between heavy metal content, leaching behavior, and carbon content in CGFA. Based on combined analyses using toxicity characteristic leaching procedure (TCLP) leaching concentrations and risk assessment code (RAC) results, it is recommended to focus on the environmental risks posed by Cd, Cr, Pb, Zn, and Hg in CGFA during their modification and utilization processes.

Machine learning-driven source identification and ecological risk prediction of heavy metal pollution in cultivated soils

To overcome challenges in assessing the impact of environmental factors on heavy metal accumulation in soil due to limited comprehensive data, our study in Yangxin County, Hubei Province, China, analyzed 577 soil samples in combination with extensive big data. We used machine learning techniques, the potential ecological risk index, and the bivariate local Moran’s index (BLMI) to predict Cr, Pb, Cd, As, and Hg concentrations in cultivated soil to assess ecological risks and identify pollution sources. The random forest model was selected for its superior performance among various machine learning models, and results indicated that heavy metal accumulation was substantially influenced by environmental factors such as climate, elevation, industrial activities, soil properties, railways, and population. Our ecological risk assessment highlighted areas of concern, where Cd and Hg were identified as the primary threats. BLMI was used to analyze spatial clustering and autocorrelation patterns between ecological risk and environmental factors, pinpointing areas that require targeted interventions. Additionally, redundancy analysis revealed the dynamics of heavy metal transfer to crops. This detailed approach mapped the spatial distribution of heavy metals, highlighted the ecological risks, identified their sources, and provided essential data for effective land management and pollution mitigation.

The effect of an acidic environment during the hydrothermal carbonization of sewage sludge on solid and liquid products: The fate of heavy metals, phosphorus and other compounds

The pH of sewage sludge is a crucial factor during the hydrothermal carbonization process that influences the characteristics of the resulting products and migration of certain compounds from the solid to liquid phase. Accordingly, this work is focused on examining the pH impact during the HTC process, in particular, pH equals 2, 3, 4, 5 and 6 on the individual hydrothermally carbonized products generated at 200 °C and 2 h residence time. For this reason, the chemical and physical indicators describing the post-processing liquid and hydrochar were determined. For instance, it was observed that the phosphorus content detected in the liquid, derived at pH2, rose significantly by 80%. Furthermore, decreasing the pH of sewage sludge had a significant impact on the ash content and the calorific value of the hydrochar. Additionally, changes in the specific surface area of hydrochar were noticed: pH = 5 and pH = 6 showed an increase of 20–30%, while for lower pH values a decrease of c.a. 26% was achieved. The distribution of heavy metals between the obtained fractions in the HTC process (solid and liquid) indicated that 92 to almost 100% of the tested heavy metals were transferred to the hydrochar. A significant effect of pH on the distribution between these fractions was observed only for Zn and Ni. For instance, for pH = 2, Zn and Ni in post-processing liquid were 34% and 29%, respectively. In addition, the sequential extraction of heavy metals from hydrochar was also performed in order to identify mobile and non-mobile phases. It was noticed that the acidic environment favours a higher amount of mobile heavy metals in hydrochar. The largest effect was observed for Cd, Pb, Cr and Cu, for which, at pH = 2, their respective amounts in the mobile fraction were 2.7; 3.6; 1.8; 6.2 times higher, compared to the hydrochar without pH correction.

Spatial distribution and health risks assessment of heavy metals in e-waste dumping sites from Pakistan.

The present study focused on to determine the concentration and health risk of heavy metals (Cu, Pb, Zn, Cd, Hg, Cr) in e-waste contaminated soils collected from different provinces of Pakistan. Further, the impact of heavy metals on soil enzyme activities and microbial community was also investigated. The concentration (mg/kg) of Hg, Zn, Fe, Cu, Pb, Cd, and Cr ranged between 0-0.258, 2.284-6.587, 3.005-40.72, 8.67-36.88, 12.05-35.03, 1.03-2.43, and33.13-60.05, respectively. The results revealed that Lahore site of Punjab province indicated more concentration of heavy metals as compared to other sites. The level of Cr at all sites whereas Hg at only two sites exceeds the World Health Organization standards (WHO) for soil. Soil enzyme activity exhibited dynamic trend among the sites. Maximum enzyme activity was observed for urease followed by phosphatase and catalase. Contamination factor (Cf), Pollution load index (PLI), and geo-accumulation index (Igeo) results showed that all the sites are highly contaminated with Cu, Cd, and Pb. Hazard index (HI) was less than 1 for children and adults suggesting non-carcinogenic health risk. Principle component analysis results depicted relation among Cr, Fr, catalase, and actinomycetes; Cd, OM, urease, and bacteria, and Pb, Cu, Zn, Hg, and phosphatase, suggesting soil enzymes and microbial community profiles were influenced by e-waste pollution. Therefore, there is a dire need to introduce sustainable e-waste recycling techniques as well as to make stringent e-waste management policies to reduce further environmental contamination.

Composition, distribution, and risk assessment of heavy metals in large-scale river water on the Tibetan Plateau

Heavy metals present in aquatic ecosystems constitute a significant threat to both the environment and human health. In this study, we analyzed various heavy metals (As, Cr, Co, Ni, Cu, Mo, Cd, Pb and Sb) using extensive surface water samples collected from the Tibetan Plateau in 2021 and 2023. Results showed that downstream water samples exhibited higher content (mean 12.6 μg/L) of heavy metals compared to those from the glacier basins. It is noteworthy that heavy metal content varied significantly both in the glacier basin and downstream (4.6–29.1 μg/L and 7.8–55.2 μg/L, respectively). However, elevated concentrations at certain sites (e.g., Saga County and Dangque Zangbu River) were primarily attributed to the disproportionate contribution of individual heavy metals, possibly stemming from specific human activities or natural conditions. In the glacier basin, only Cr exhibited a decreasing trend in enrich factors (EF) with increasing Sc concentration, whereas, in the downstream areas, most elements displayed a declining trend. Furthermore, apart from a few sampling sites, heavy metal concentrations in the glacier basin remained relatively balanced, suggesting that these metals predominantly originate from natural sources. The values of potential ecological risk for an individual element (Eri) and potential ecological risk index (PER) indicate that the ecological and human risks associated with almost heavy metals (except As) in the aquatic ecosystem are minimal. Environmental ImplicationHeavy metals in aquatic ecosystems pose a significant threat to ecological and human health. Due to delicate ecological balance of the Tibetan Plateau and its critical role as a water resource, we analyzed various heavy metals (As, Cr, Co, Ni, Cu, Mo, Cd, Pb and Sb) concentrations and EF in land surface river water, to find out the pollution levels and possible sources of heavy metals in the aquatic ecosystems. The results of risk assessment showed that the prevention and management of arsenic in Tibetan Plateau needs attention, but most heavy metals pose no threaten to ecological and human health.

Spatial distribution, pollution level and human health risk assessment of heavy metals in urban street dust at neighbourhood scale.

Urban street dust (UStD) is a vital issue for human health and is crucial for urban sustainability. This study aims to enhance the creation of safe, affordable, and resilient cities by examining environmental contamination and health risks in urban residential areas. Specifically, it investigates the concentrations and spatial distribution of chromium (Cr), cadmium (Cd), nickel (Ni), copper (Cu), lead (Pb), and zinc (Zn) in UStD in Yenimahalle, Ankara. The mean concentrations of Zn, Cr, Pb, Cd, Ni, and Cu in UStD were 97.98, 66.88, 55.22, 52.45, 38.37, and 3.81 mg/kg, respectively. The geoaccumulation pollution index (Igeo) values for these elements were: Cd (5.12), Ni (1.61), Cr (1.21), Pb (1.13), Cu (0.78), and Zn (0.24). These indices indicate that the area is moderately polluted with Cr, Pb, and Ni, uncontaminated to moderately contaminated with Cu and Zn, and extremely polluted with Cd. The hazard index (HI) values for Cr, Cd, Ni, Cu, Pb, and Zn were below the non-carcinogenic risk threshold for adults, indicating no significant risk. However, for children, the HI values for Pb, Ni, Cd, and Zn were 3.37, 1.80, 1.25, and 1.25, respectively, suggesting a higher risk. Carcinogenic risk (RI) of Cd, Ni, and Pb was significant for both children and adults, indicating that exposure through ingestion, inhalation, and dermal contact is hazardous. The findings highlight the need for strategic mitigation measures for both natural and anthropogenic activities, providing essential insights for residents, policymakers, stakeholders, and urban planners.

Microplastic and Heavy Metals Distributions in Urban Rivers Sediments, China

Microplastic and Heavy Metals Distributions in Urban Rivers Sediments, China

Distribution of trace metals and metalloids in tissues of Eurasian Woodcock (Scolopax rusticola) from Southern Italy

Distribution of trace metals and metalloids in tissues of Eurasian Woodcock (Scolopax rusticola) from Southern Italy

Heteroatom-doped cobalt single-atomic nanozymes with differential enzyme-like activity for bacteria-infected wound therapy

Single-atom nanozymes (SANZs) have emerged as new media for enhancing chemodynamic therapy (CDT) to achieve desirable enzyme-like effects and excellent nanoscale specificity. However, non-optimal adsorption of Fenton-like reaction intermediates prevents SANZs from exerting kinetic activity and hinders the CDT effect. Herein, we demonstrate that heteroatom-doped Co single-atom nanozymes (SACNZs) with intrinsic charge transfer exhibit peroxidase-like properties and significantly improve the ability of CDT to treat Staphylococcus aureus-infected wounds. Density functional theory calculations showed that the S-induced charge transfer effect regulated the electronic distribution of the central metal more efficiently than P, thereby lowering the energy levels for the generation of OH and increasing the catalytic effect. Polyvinylpyrrolidone-modified SACNZs showed effects consistent with this theory in both in vitro antibacterial and in vivo ward management assays. This study systematically investigated the relationship between heteroatom-doping and the catalytic activity of metal centres, opening a new perspective for the application of CDT.

Spatiotemporal interpretable mapping framework for soil heavy metals

Mapping the spatiotemporal distribution of soil heavy metals is a prerequisite for soil pollution prevention and control. However, current mapping methods make it difficult to balance robustness and interpretability. In this study, we proposed a spatiotemporal interpretable mapping framework for soil heavy metals and conducted a case study of soil cadmium (Cd) in cropland of the Poyang Lake region in China. The results showed that the average soil Cd concentration increased significantly (p < 0.01) from 0.13 mg/kg in 1983 to 0.19 mg/kg in 2010. Soil Cd in 1983 was mainly controlled by human activities and topography, whereas it was jointly driven by human activities, topography, and climate in 2010. In addition, the framework revealed the spatial distribution of soil Cd and their uncertainties at a 12.5-m resolution in 1983 (R2 = 0.94) and 2010 (R2 = 0.97). The top three covariates in 1983 were nighttime-light, PM10, and land surface temperature (day), whereas those in 2010 were mean annual minimum temperature, gross domestic product, and industrial enterprises, with Shapley additive explanation (SHAP) values of 0.44, 0.42, and 0.27, and 0.31, 0.11, and 0.09 mg/kg, respectively. By integrating machine learning, variable and model selection, and the SHAP module, the proposed framework achieves a balance between the robustness and interpretability in mapping the spatiotemporal distribution of soil Cd, going beyond the limitations of the classical statistical “smoothing effect” and the artificial intelligence “black box.” Our study emphasizes the importance of considering time, space, models, variables, and mechanisms in digital soil mapping, which will enable more accurate and scientific predictions of soil contaminants across time and space.

Effects of dissolved organic matter on distribution characteristics of heavy metals and their interactions with microorganisms in soil under long-term exogenous effects

Long-term waste accumulation (LTWA) in soil not only alters its physical and chemical properties but also affects heavy metals and microorganisms in polluted soil through the dissolved organic matter (DOM) it produces. However, research on the impact of DOM from LTWA on heavy metals and microorganisms in polluted soil is limited, which has resulted in an incomplete understanding of the mechanisms involved in LTWA soils remediation. This study focuses on the DOM generated by waste accumulation and analyses the physicochemical properties, microbial community structure, and vertical distribution of heavy metals in four types of LTWA soils at different depths (0–100 cm). A causal analysis is conducted using structural equation modelling. The results indicate that due to the retention effect of the soil and microorganisms, heavy metal pollution is concentrated on the soil surface layer (>30 cm). With increasing depth, there is a decrease in heavy metal concentration and an increase in microbial diversity and abundance. DOM plays a significant role in regulating the concentration of soil heavy metals and the diversity and abundance of microorganisms. The DOM from different soils gradually transforms into substances dominated by tyrosine, tryptophan, and fulvic acid, which sustain the normal life activities and gene expression of microorganisms. Bacteria such as Pseudarthrobacter, Desulfurivibrio, Thiobacillus, and Sulfurimonas, which are involved in energy transformation, along with genes such as water channel protein and YDIF, which enhance heavy metal metabolism, ensure that microbial communities can maintain basic life processes in polluted environments and gradually select for dominant species that are adapted to heavy metal pollution. These novel discoveries illuminate the potential for modulating the composition of DOM to amplify microbial activity, while concurrently offering insights into the migration patterns of various long-term exogenous pollutants. This foundational knowledge provides a foundation for the development of efficacious remediation strategies.

Assessment of Heavy Metals Using the Enrichment Factor and Geoaccumulation Index in Menjer Lake, a Tropical Volcanic Lake

Lakes are recognized as vulnerable to pollution, including Menjer Lake, whose catchment area is dominated by agricultural lands and features floating net cages in the water body. The heightened contamination risk within the lake primarily stems from the accumulation of heavy metals, compounds known for their profound toxicity. The high-level concentration of heavy metal in sediment aligns with the level of water toxicity, underscoring the urgent need for thorough assessment and monitoring. The research focused on assessing heavy metal concentration and distribution through spatial analysis. Toxicity levels were evaluated using the enrichment factor (EF) and Geoaccumulation Index (Igeo). This study collected eight samples each during the rainy season of 2022 and 2023. The heavy metals were tested using an Atomic Absorption Spectrophotometer (AAS), including Pb, Cd, Cr, Fe, Al, and Cu. Comparatively, the mean concentration of heavy metals in 2023 was slightly higher for Fe and Al than in 2022. Moreover, Cd was not detected in either 2022 or 2023. The variety of land use and land cover has consequences on the spatial distribution of toxicity levels, showing an influential correlation between Al, Pb, and Fe metals with locations associated with cropland and floating net cages. Additionally, highly steep slopes significantly affected erosions that induced sediment from agricultural land use, further underscoring the multifaceted nature of environmental risk factors.

Very metal-poor stars I: a catalogue derived from LAMOST DR9

ABSTRACT In this paper, a semisupervised machining learning technique had been utilized to analyse low-resolution stellar spectra from Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) Data Release 9 (DR9). We identified approximately 111 000 potential very metal-poor stars. Estimation of their stellar parameters ($T_{\rm eff}$, ${\rm log}\, \rm {g}$, [Fe/H]) indicate that over 99 per cent are metal-poor ([Fe/H] &amp;lt; −1.0), comprising 32 631 very metal-poor ([Fe/H] &amp;lt; −2.0), 702 extremely metal-poor ([Fe/H] &amp;lt; −3.0) and 30 ultra metal-poor ([Fe/H] &amp;lt; −4.0) stars. Based on kinematic characteristics, stars were categorized into thick disc-like, thin disc-like, and halo-like groups. We analysed their metallicity distributions (MDs) with respect to vertical height ($|Z|$) and orbital eccentricity (e). Thick disc-like stars in current sample show a clear trend of decreasing metallicty with increasing $|Z|$ or e for the ranges −3.0 $\lt $ [Fe/H] $\lt $ −1.2 and $|Z|$$\lt $ 3 kpc. Conversely, thin disc-like stars in current sample exhibit a slight increase in the fraction of more metal-poor stars with $|Z|$ for the ranges −3.0 $\lt $ [Fe/H] $\lt $ −1.2 and $|Z|$$\lt$ 1 kpc, but no obvious correlation with e. Additionally, we confirmed the presence of two prominent substructures among halo-like stars. One exhibits a high eccentricity ($e\ \gt\ 0.8$) orbit and higher metallicity, while the other follows a retrograde orbit with moderate eccentricity ($e\sim 0.6$) and lower metallicity. We believe they are related to the merger events known as Gaia Sausage and Sequoia, respectively. Furthermore, our observations indicate that the Sequoia has lower eccentricity and metallicity compared to the Gaia Sausage.

Microbial Mobilization and Reprecipitation of Transition Metals in Waste Rock from an Abandoned Pyrite Mine: Implications for Metal Recovery

Abstract The Pyrite Mines in Sulphide, Ontario are a collection of historic mine workings representing one of more than 6000 abandoned mines in Ontario. Historic mines are receiving renewed interest as potential sources of critical minerals for use in low carbon technologies. This study characterizes waste rock from the Pyrite Mines in the context of metal distribution, microbial activity, bioleaching, and acid mine drainage (AMD) bioremediation for the recovery of metals. Acidophilic Fe-oxidizing bacteria cultured from the waste rock produced schwertmannite [Fe8O8(OH)8−2x(SO4)x·nH2O] and ammoniojarosite [NH4Fe3(SO4)2(OH)6] with similar morphologies to those often observed in acidic sulfidic mine settings. Fe- and S-oxidizing bacteria found naturally in the waste rock were used in waste rock bioleaching column experiments that demonstrated AMD formation and metal mobilization. The columns produced acidic leachates (pH = 1.75) containing dissolved constituents, including sulfur (1577 mg/L), iron (547.7 mg/L), nickel (12.6 mg/L), manganese (7.3 mg/L), copper (2.3 mg/L), zinc (2.0 mg/L), chromium (1.5 mg/L), and titanium (0.7 mg/L). The proportion of metals successfully leached from the waste rock was variable, with leaching efficiencies calculated for nickel (31%), manganese (10.5%), iron (1.5%), chromium (1.4%), and titanium (0.02%). The leachates produced by the bioleaching columns were amended in subsequent bioremediation columns using sulfate reducing bacteria cultured from the mine site. Remediation efficiencies for elements of interest were calculated as cobalt (100%), chromium (100%), copper (100%), iron (90%), titanium (68%), nickel (52%), manganese (52%), and sulfur (43%). Mapping elemental distributions in thin sections from one of the bioleaching columns using synchrotron X-ray fluorescence microscopy revealed the heterogeneity of the waste rock. Iron was observed in both euhedral mineral grains, likely pyrite, and in secondary cements coating grains in the waste rock. Nickel, manganese, and chromium were primarily co-located with the iron. Titanium was primarily co-located with calcium in titanite (CaTiSiO5), making it challenging to target with bioleaching. This study demonstrates the heterogeneous nature of metal distribution in waste rock from this historic mine site. It indicates that successful metal recovery from legacy mine waste will require such materials to be treated as anthropogenic mineral deposits that require “exploration” and characterization much like naturally occurring ore deposits.

Distinctive Pattern of Metal Deposition in Neurologic Wilson Disease: Insights From 7T Susceptibility-Weighted Imaging.

Noninvasive and accurate biomarkers of neurologic Wilson disease (NWD), a rare inherited disorder, could reduce diagnostic error or delay. Excessive subcortical metal deposition seen on susceptibility imaging has suggested a characteristic pattern in NWD. With submillimeter spatial resolution and increased contrast, 7T susceptibility-weighted imaging (SWI) may enable better visualization of metal deposition in NWD. In this study, we sought to identify a distinctive metal deposition pattern in NWD using 7T SWI and investigate its diagnostic value and underlying pathophysiologic mechanism. Patients with WD, healthy participants with monoallelic ATP7B variant(s) on a single chromosome, and health controls (HCs) were recruited. NWD and non-NWD (nNWD) were defined according to the presence or absence of neurologic symptoms during investigation. Patients with other diseases with comparable clinical or imaging manifestations, including early-onset Parkinson disease (EOPD), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and neurodegeneration with brain iron accumulation (NBIA), were additionally recruited and assessed for exploratory comparative analysis. All participants underwent 7T T1, T2, and high-resolution SWI scanning. Quantitative susceptibility mapping and principal component analysis were performed to illustrate metal distribution. We identified a linear signal intensity change consisting of a hyperintense strip at the lateral border of the globus pallidus in patients with NWD. We termed this feature "hyperintense globus pallidus rim sign." This feature was detected in 38 of 41 patients with NWD and was negative in all 31 nNWD patients, 15 patients with EOPD, 30 patients with MSA, 15 patients with PSP, and 12 patients with NBIA; 22 monoallelic ATP7B variant carriers; and 41 HC. Its sensitivity to differentiate between NWD and HC was 92.7%, and specificity was 100%. Severity of the hyperintense globus pallidus rim sign measured by a semiquantitative scale was positively correlated with neurologic severity (ρ = 0.682, 95% CI 0.467-0.821, p < 0.001). Patients with NWD showed increased susceptibility in the lenticular nucleus with high regional weights in the lateral globus pallidus and medial putamen. The hyperintense globus pallidus rim sign showed high sensitivity and excellent specificity for diagnosis and differential diagnosis of NWD. It is related to a special metal deposition pattern in the lenticular nucleus in NWD and can be considered as a novel neuroimaging biomarker of NWD. The study provides Class II evidence that the hyperintense globus pallidus rim sign on 7T SWI MRI can accurately diagnose neurologic WD.

Spatial distribution and health risk assessment of heavy metals in drinking water in Nikshahr and Iranshahr cities of Iran

ABSTRACT The presence of high concentrations of certain heavy metals (HMs) in drinking water poses a serious threat to the health of consumers. This work was done to investigate the concentration of heavy metals such as Arsenic (As) cadmium (Cd), chromium (Cr), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb) and cobalt (Co) in the water resources of two cities of Iranshahr and Nikshahr in the south of Sistan and Baluchistan province. For this aim, 24 samples of drinking water sources were collected and the concentration of heavy metals was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results of samples of these networks showed that the average concentration of Pb (11.25 μg/L), Hg (10.33 μg/L), As (10.62 μg/L) and Cd (3.45 μg/L) far exceeds the standard of the World Health Organisation. The average concentration of heavy metals in the drinking water of Iranshahr and Nikshahr is respectively Fe>Pb>As>Hg>Ni>Cr>Co>Cd and Fe>Pb>As> Ni > Cr >Co>Cd> Hg. Potential sources of pollution in this study are attributed to infiltration of industrial effluents and agricultural runoff, which is a significant threat to groundwater quality. The calculated hazard quotients (HQ(values for non-carcinogenic risk show that this value is less than 1 in most metals, but the hazard index)HI) in children is greater than 1, and non-carcinogenic risk is evident. HI was obtained for children 5.4 and adults 2.6. However, the risk of carcinogenics in children and adults is equal to 2.66 E-05 and1.3E–6, respectively, and the increase in the risk of cancer in children is higher due to the consumption of drinking water. Therefore, it is necessary to protect water sources, water treatment and monitor more water distribution networks based on the water safety plan.

Composition of heavy metals in sediment, water, and fish of the Ganga and Yamuna Rivers in two major cities of India.

The rapid industrial development in the Indian capital region has led to significant waste generation, which, despite undergoing treatment prior to disposal, contributes substantially to water body contamination. Given the diverse nature of these wastes and their potential repercussions across the food chain, a study was conducted to evaluate heavy metal contamination levels in the Ganga and Yamuna Rivers of two major cities. Six heavy metals (Pb, Cd, Hg, Cu, Cr, and Zn) were analyzed in fish, water, and sediment samples by utilizing flame atomic absorption spectrophotometry (Avanta Σ) from March 2019 to February 2020. Results revealed distinct heavy metal distribution patterns, with Cr > Zn > Pb > Cu > Cd > Hg in the Ganga River and Zn > Cr > Pb > Cu > Cd > Hg in the Yamuna River for fish samples. Additionally, levels of Hg in Cyprinus carpio and Sperata oar from the Ganga River, and Pb, Cd, Hg, and Cr in Salmophasia bacaila and Mystus cavasius from the Yamuna River exceeded WHO/FAO permissible limits. In water samples, the predominant heavy metal sequences were Pb > Cu > Zn > Cr > Cd > Hg for the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg for the Yamuna River, with Pb, Cr, Zn, and Cd surpassing WHO standards. Sediment analysis revealed varying heavy metal compositions, with Zn > Cr > Pb > Cu > Cd > Hg in the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg in the Yamuna River. While drinking water and fish from the Ganga River were deemed safe for consumption, those from the Yamuna River were not. Given the toxic nature of heavy metals and their detrimental health impacts, regular monitoring and effective management strategies are imperative.

Vertical distribution of microplastics in an agricultural soil after long-term treatment with sewage sludge and mineral fertiliser

Sewage sludge applications release contaminants to agricultural soils, such as potentially toxic metals and microplastics (MPs). However, factors determining the subsequent mobility of MPs in long-term field conditions are poorly understood. This study aimed to understand the vertical distribution of MPs in soils amended with sewage sludge in comparison to conventional mineral fertiliser for 24 years. The depth-dependent MP mass and number concentrations, plastic types, sizes and shapes were compared with the distribution of organic carbon and metals to provide insights into potentially transport-limiting factors. Polyethylene, polypropylene and polystyrene mass concentrations were screened down to 90 cm depth via pyrolysis-gas chromatography/mass spectrometry. MP number concentrations, additional plastic types, sizes, and shapes were analysed down to 40 cm depth using micro-Fourier transform-infrared imaging. Across all depths, MP numbers were twice and mass concentrations 8 times higher when sewage sludge was applied, with a higher share of textile-related plastics, more fibres and on average larger particles than in soil receiving mineral fertiliser. Transport of MPs beyond the plough layer (0–20 cm) is often assumed negligible, but substantial MP numbers (42 %) and mass (52 %) were detected down to 70 cm in sewage sludge-amended soils. The initial mobilization of MPs was shape- and size-dependent, because the fractions of fragmental-shaped and relatively small MPs increased directly below the plough layer, but not at greater depths. The sharp decline of total MP concentrations between 20 and 40 cm depth resembled that of metals and organic matter suggesting similar transport limitations. We hypothesize that the effect of soil management, such as ploughing, on soil compactness and subsequent transport by bioturbation and via macropores drives vertical MP distribution over long time scales. Risk assessment in soils should therefore account for considerable MP displacement to avoid underestimating soil exposure.

Risk assessment of heavy metals and total petroleum hydrocarbons (TPHs) in coastal sediments of commercial and industrial areas of Hormozgan province, Iran.

The significant increase in the pollution of heavy metals and organic pollutants, their stable nature, and their high toxicity are gradually becoming a global crisis. In a recent study, a comprehensive assessment of the spatial distribution of heavy metals and total petroleum hydrocarbons (TPHs), as well as an assessment of their ecological risks in the sediments of 32 stations located in commercial and industrial areas (Mainly focusing on petrochemical and power industries, desalination plants and transit Ports) of Hormozgan province (East and West of Jask, Bandar Abbas, Qeshm, and Bandar Lengeh) was performed during 2021-2022. The sediment samples were digested with HNO3, HCl and HF solvents. The concentration of heavy metals was determined with furnace and flame systems of atomic absorption spectrometer. The concentration of heavy metals showed significant spatial changes between stations. The ecological assessment indices between the regions indicated that the stations located in Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan had a higher intensity of pollution than other places and significant risks of pollution, especially in terms of Cr and Ni. The average contamination degree (CD) (14.89), modified contamination degree (MCD) (2.48), pollution load index (PLI) (2.32), and potential ecological risk index (PERI) (100.30) showed the sediments in the area of Shahid Bahonar Port, Suru beach and Khor gorsouzuan, experience significant to high levels of pollution, especially Cr and Ni. Using contamination factor (CF) and Geoaccumulation index (Igeo), Cr was considered the most dangerous metal in the studied areas. Based on the global classification of marine sediment quality for the concentrations of TPHs, the sediments of the studied stations were classified as non-polluted to low pollution. In all regions, indices of the PELq (General toxicity) and CF (Contamination factor) were much lower than 0.1 and 1 respectively, showing the absence of adverse biological effects caused by TPHs in sediments. It is necessary to consider comprehensive and impressive strategies to control and reduce pollution of heavy metals, especially in the areas of Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan, so that the sources of this pollution are required to be identified and managed.