Impact of manganese mining on potentially toxic elements pollution and bioaccumulation in Spirogyra varians and Hydrilla verticillata in the Xiaojiang River.

Potentially toxic elements (PTEs) pose a significant threat to aquatic ecosystems. This study investigated the content and potential sources of PTEs (Cr, Mn, Ni, Cu, Zn, Cd, Pb) in water, sediment, and dominant aquatic plants (Hydrilla verticillata and Spirogyra varians) in the Xiaojiang River, located near the Zhaiying manganese mine in Guizhou Province, China. Correlation analysis, principal component analysis (PCA), and cluster analysis were employed to assess PTE distribution and potential sources. Water PTE concentrations complied with the Class II standard (GB3838-2002), indicating no water pollution. However, sediment PTE levels exceeded background values, particularly Mn, which exhibited moderate to strong contamination. Cd also showed moderate contamination, posing a considerable ecological risk. Cd was the main potential pollutant with the highest contribution rate. Mn and Cd were therefore identified as priority pollutants requiring targeted abatement strategies. Mining activities likely represent the primary source, but combined pollution from vehicle traffic and agriculture might also contribute. Hydrilla verticillata demonstrated a higher capacity for PTE enrichment from sediment compared to Spirogyra varians, suggesting its potential for sediment remediation (except for Cu). A significant correlation existed between both plant species and sediment PTE content. PCA supported the association between S. varians and sediment PTEs. Linear regression analyses revealed better correlations between S. varians and sediment Mn, Ni, Cu, and Zn (0.77, 0.68, 0.82, and 0.79, respectively). Taken together, these findings suggest that S. varians serves as an effective bioindicator for monitoring sediment contamination with PTEs.

Long-term performance of the adsorption layer system for the recycling and repurposing of arsenic-bearing mudstone as road embankment.

The adsorption layer system has shown great potential as a cost-effective and practical strategy for the recycling and management of excavated rocks containing potentially toxic elements (PTEs). Although this system has been employed in various civil engineering projects throughout Japan, its long-term performance to immobilize PTEs has rarely been investigated. This study aims to evaluate the effectiveness of the adsorption layer system applied in an actual road embankment approximately 11 years after construction. The embankment system is comprised of a layer of excavated arsenic (As)-bearing mudstone built on top of a bottom adsorption layer mixed with an iron (Fe)-based adsorbent. Collection of undisturbed sample was carried out by implementing borehole drilling surveys on the embankment. Batch leaching experiments using deionized water and hydrochloric acid were conducted to evaluate the water-soluble and acid-leachable concentrations of As, Fe, and other coexisting ions. The leaching of As from the mudstone layer was likely induced by As desorption from Fe-oxides/oxyhydroxides naturally present under alkaline conditions, including the oxidation of framboidal pyrite, which was identified as a potential source of As. This was supported by electron probe microanalyzer (EPMA) observations showing the presence of trace amounts of As in framboidal pyrite crystals. Arsenic leached from the mudstone layer was then immobilized by Fe oxyhydroxides found in the adsorption layer. Based on geochemical modeling and X-ray photoelectron spectroscopy (XPS) results, leached As predominantly existed as the negatively charged HAsO42- oxyanion, which is readily sequestered by Fe oxyhydroxides. Moreover, the effectiveness of the adsorption layer was assessed and its lifetime was estimated, and the results revealed it still possessed enough capacity to adsorb As released from mudstone in the foreseeable future. This prediction utilized the maximum potential amount of As that could leach from the excavated rock layer with time.

Fractionation, spatial distribution, ecological and health risk assessment of cobalt and nickel in surface sediment of a bay along the southeast coast of China.

The fractionation and distribution of two potentially toxic elements (Co and Ni) were investigated in surface sediments to explore the pollution in Xiamen Bay, a special zone experiencing rapid economic growth and enormous environmental pressure. Relatively high concentrations were observed in nearshore areas with frequent human activities. The dominant fractions for Co and Ni were found to be residual, followed by exchangeable phase. Spatial differences in mobility and bioavailability inferred from chemical fractionations were more pronounced for Ni. Multiple evaluation methods including geo-accumulation index, risk assessment code, modified potential ecological risk index, etc., consistently indicated that pollution levels and ecological risks in the entire bay were generally classified as medium-low. However, non-carcinogenic risks of Co for children and carcinogenic risks of Ni for adults exceeded safety thresholds. Terrestrial weathering processes and industrial activities primarily contributed to the presence of these elements, while their distributions were mainly influenced by organic matter.

Investigation of groundwater quality in the Southern Coast of the Black Sea: application of computational health risk assessment in Giresun, Türkiye.

Potentially toxic elements (PTEs), especially arsenic in drinking water, pose significant global health risks, including cancer. This study evaluates the groundwater quality in Giresun province on the Black Sea coast of Türkiye by analyzing twelve groundwater resources. The mean concentrations of macronutrients (mg/L) were: Ca (10.53 ± 6.63), Na (6.81 ± 3.47), Mg (3.39 ± 2.27), and K (2.05 ± 1.10). The mean levels of PTEs (µg/L) were: Al (40.02 ± 15.45), Fe (17.65 ± 14.35), Zn (5.63 ± 2.59), V (4.74 ± 5.85), Cu (1.57 ± 0.81), Mn (1.02 ± 0.76), As (0.93 ± 0.73), Cr (0.75 ± 0.57), Ni (0.41 ± 0.18), Pb (0.36 ± 0.23), and Cd (0.10 ± 0.05). All PTE levels complied with WHO drinking water safety guidelines, and overall water quality was excellent. The heavy metal evaluation index (HEI < 10) and heavy metal pollution index (HPI < 45) indicate low pollution levels across all stations. Irrigation water quality was largely adequate, as shown by the magnesium hazard (MH), sodium adsorption ratio (SAR), Na%, and Kelly's ratio (KR). The total hazard index (THI) values consistently remained below 1, indicating no non-carcinogenic health risks. However, at station 10 (city center), the cancer risk (CR) for adults due to arsenic was slightly above the threshold (1.44E-04). Using principal component analysis (PCA), positive matrix factorization (PMF), and geographic information system (GIS) mapping, the study determined that most PTEs originated from natural geological formations or a combination of natural and human sources, with minimal impact from human activities. These findings highlight the safety and reliability of the groundwater sources studied, emphasizing their potential as a long-term, safe water supply for nearby populations.

Accurate prediction of spatial distribution of soil potentially toxic elements using machine learning and associated key influencing factors identification: A case study in mining and smelting area in southwestern China.

Accurate prediction of spatial distribution of potentially toxic elements (PTEs) is crucial for soil pollution prevention and risk control. Achieving accurate prediction of spatial distribution of soil PTEs at a large scale using conventional methods presents significant challenges. In this study, machine learning (ML) models, specially artificial neural network (ANN), random forest (RF), and extreme gradient boosting (XGB), were used to predict spatial distribution of soil PTEs and identify associated key factors in mining and smelting area located in Yunnan Province, China, under the three scenarios: (1) natural + socioeconomic + spatial datasets (NS), (2) NS + irrigation pollution index (IPI) datasets, (3) NS + IPI + deposition (DEPO) datasets. The results highlighted the combination of NS+IPI+DEPO yielded the highest predictive accuracy across ML models. Particularly, XGB exhibited the highest performance for As (R2 =0.7939), Cd (R2 =0.6679), Cu (R2 =0.8519), Pb (R2 =0.8317), and Zn (R2 =0.7669), whereas RF performed the best for Ni (R2 =0.7146). The feature importance and Shapley additive explanation (SHAP) analysis revealed that DEPO and IPI were the pivotal factors influencing the distribution of soil PTEs. Our findings highlighted the important role of DEPO in spatial distribution prediction of soil PTEs, which has often been ignored in previous studies.

RESEARCH OF THE IMPACT OF ENVIRONMENTALLY PERSISTENT FREE RADICALS ON CHEMICAL ELEMENT BEHAVIOUR IN THE SOIL-PLANT SYSTEM.

Environmentally persistent free radicals (EPFRs) may pose a potential risk to the ecosystem and human health via oxidation stress and are considered emerging contaminants. Being stable with a lifetime of minutes or several months and abundant in transitional matrices (e.g. biochar), EPFRs continue to affect deposits (e.g. soil) and related media (plants) when the transitional matrices (e.g. biochar) are applied. The impact of EPFR on the plant uptake of chemical elements (CEs) was studied in the field conditions where, for two years, biochar and fertilisers were applied to the agricultural soil for winter triticale cultivation. EPFRs determination methods, along with the element uptake indices (bioaccumulation and biophilicity) and the method of the dynamic factors were applied. Results have shown that EPFRs have influenced the soil properties relevant to CE soil bioavailability and bioaccumulation in plants. The impact of EPFRs on CE transport in the soil-plant system was observed to influence the biogeochemical behaviour of CEs in the soil-plant system. This work provides the first findings on EPFRs-induces changes on CE bioavailability and bioaccumulation intensity, indicating the higher plant uptake risk of some potentially toxic elements (such as Cr).

Enhanced Removal of Cd(II) Ions from Aqueous Media via Adsorption on Facilely Synthesized Copper Ferrite Nanoparticles.

In this study, magnetic copper ferrite (CuFe2O4) nanoparticles were synthesized via the Pechini sol-gel method and evaluated for the removal of Cd(II) ions from aqueous solutions. PF600 and PF800 refer to the samples that were synthesized at 600 °C and 800 °C, respectively. Comprehensive characterization using FTIR, XRD, FE-SEM, HR-TEM, and EDX confirmed the successful formation of CuFe2O4 spinel structures, with crystallite sizes of 22.64 nm (PF600) and 30.13 nm (PF800). FE-SEM analysis revealed particle diameters of 154.98 nm (PF600) and 230.05 nm (PF800), exhibiting spherical and irregular shapes. HR-TEM analysis further confirmed the presence of aggregated nanoparticles with average diameters of 52.26 nm (PF600) and 98.32 nm (PF800). The PF600 and PF800 nanoparticles exhibited exceptional adsorption capacities of 377.36 mg/g and 322.58 mg/g, respectively, significantly outperforming many materials reported in the literature. Adsorption followed the Langmuir isotherm model and pseudo-second-order kinetics, indicating monolayer adsorption and strong physisorption. The process was spontaneous, exothermic, and predominantly physical. Reusability tests demonstrated high adsorption efficiency across multiple cycles when desorbed with a 0.5 M ethylenediaminetetraacetic acid (EDTA) solution, emphasizing the practical applicability of these nanoparticles. The inherent magnetic properties of CuFe2O4 facilitated easy separation from the aqueous medium using a magnet, enabling efficient and cost-effective recovery of the adsorbent. These findings highlight the potential of CuFe2O4 nanoparticles, particularly PF600, for the effective and sustainable removal of Cd(II) ions from water.

Bioaccumulation dynamics, noncarcinogenic and carcinogenic risks of heavy metals in commercially valuable shellfish and finfish species from the world largest floating slum, Makoko, Nigeria.

This study examined ten heavy metals in five species: Macrobrachium vollenhovenii, Penaeus monodon, P. notialis, Chloroscombrus chrysurus, and Pseudotolithus typus, from Makoko floating slum, Lagos Lagoon to discern their bioaccumulation potentials, sources of origin, and health implications. The concentrations were in this order: Fe (4.172-10.176) > Zn (1.310-5.754) > Mn (0.475-2.330) > Cu (0.238-1.735) > Pb (0.121-0.391) > Cd (0.055-0.283) > Co (0.056-0.144) > Ni (0.039-0.121) > Cr (0.022-0.095) > As (0.003-0.031) mg/kg. The MPDI denotes "low toxicity," and the BAF/BSAF revealed that benthic species had higher bioconcentration potentials. Multivariate analyses revealed that heavy metals exhibited mutual relationships during chemical transport, and their sources were both geogenic and human-induced. The HI values were below 1, and the TCR values were below the threshold of 1 × 10-4. This suggests that the probabilities of noncancer and carcinogenic risks in human populations due to long-term consumption of the evaluated species are unlikely.

Seasonal variation and human health risk assessment of potentially toxic elements in pharmaceutical effluents around Ilorin metropolis, Nigeria.

Potentially toxic elements (PTEs) are widely released into the environment as a result of increased urban and industrial development in recent years. The bulk of PTEs are cancer-causing and harm human health by producing free radicals. As a result, it is crucial to monitor, evaluate, and limit the effects of the elements on human health. In this study, levels of PTEs (As, Cr, Cd, Ni, Co, and Pb) in pharmaceutical effluents discharged along the Asa River around the Ilorin metropolis and their seasonal variations were evaluated. Water samples were collected from eight different locations over a two-season period along the river and analyzed for PTEs using atomic absorption spectrophotometry and an inductively coupled plasma optical emission spectrometer. As, Cd, Pb, Cr, Ni, and Co had mean PTE values in the effluents (both seasons) of 0.0258, 0.0233, 0.00193, 0.0176, and 0.0164 mg/L, respectively, with As and Pb surpassing the WHO standard. Maximum temperature and pH were measured for the physicochemical parameters in the wet season, whereas electrical conductivity and total dissolved solids were seen in the dry season. The average values of the metals in the human risk assessment for carcinogenicity were As > Cd > Pb > Cr > Ni > Co, with As above the recommended threshold in several locations. However, all of the metal hazard indices were < 1, indicating that the waters were suitable for domestic purposes. Nonetheless, the relevant authorities should mandate that pharmaceutical effluents be treated before being released into bodies of water.

A 6-year review status on soil pollution in coal mining areas from Europe.

Coal is an essential component in achieving the goal of fulfilling the energy demands of the world. Nevertheless, the extensive practice of coal mining has resulted in environmental contamination through the release of both organic and inorganic pollutants, including polycyclic aromatic compounds and potentially toxic elements, into various mediums, notably soil. The escalating coal-mining activities across Europe have amplified the concentration of specific elements in the soil. Therefore, a thorough and meticulous assessment of these environmental impacts is imperative to furnish policymakers, industries, and communities with valuable insights, facilitating the formulation and adoption of effective mitigation strategies. Considering the results of studies from 2018 to 2023, this review thoroughly evaluates the current state of soil pollution in the coal mining areas of Europe, focusing on polycyclic aromatic hydrocarbons and potentially toxic elements. By analyzing the acquired data, this study aims to evaluate the levels of contamination by these pollutants in soils. The findings reveal that low molecular weight polycyclic aromatic hydrocarbons dominate the polycyclic aromatic compounds present, while potentially toxic elements including Zn, Pb, Mn, and Cr emerge as major contributors to soil contamination in coal mining areas from Europe.

A review on e-waste contamination, toxicity, and sustainable clean-up approaches for its management.

Ecosystems and human health are being negatively impacted by the growing problem of electrical waste, especially in developing countries. E-waste poses a significant risk to ecological systems because it can release a variety of hazardous substances into the environment, containing polybrominated diphenyl ethers and heavy metals, brominated flame retardants, polychlorinated dibenzofurans and polycyclic aromatic hydrocarbons, and dioxins. This review article provides a critical assessment of the toxicological consequences of e-waste on ecosystems and human health and data analyses from scientific journals and grey literature on metals, BFRs, PBDEs, PCDFs, and PAHs in several environmental compartments of commercial significance in informal electronic trash recycling. The currently available techniques and tools employed for treating e-waste are sustainable techniques such as bioremediation, chemical leaching, biological leaching, and pyrometallurgy have been also discussed along with the necessity of implementing strong legislation to address the issue of unregulated exports of electronic trash in recycling practices. Despite the ongoing hurdles, implementing environmentally sustainable recycling methods have the potential to address the detrimental impacts of e-waste and foster positive economic development.

Plastic Pollution in Paradise: Analyzing Plastic Litter on Malta's Beaches and Assessing the Release of Potentially Toxic Elements.

This study investigates plastic litter on two beaches in Malta, Golden Bay and Rivera Beach, with a focus on plastic abundance, characteristics, sources, and the influence of human activity on pollution levels. Conducted in March 2023 during the low-tourist season, 13 sediment samples were collected from a depth of 5 cm using a systematic square sampling method. Plastic litter was quantified and sorted by size, shape, color, and polymer type, and concentrations of potentially toxic elements (PTEs) were measured (Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Fe via ICP-OES). Golden Bay exhibited significantly higher plastic quantities (53.9 ± 4.3 n/m2) compared to Rivera Beach (29.7 ± 4.0 n/m2). Microplastics were dominant on both beaches, with Golden Bay showing a higher proportion (57.0%) than Rivera Beach (50.6%). The plastic litter predominantly consisted of PE (59.6-68.0%) and PP (29.6-38.8%). Golden Bay plastics had PTE concentrations up to 4.9 times higher than those in Rivera Beach, notably for Mn (309.0 µg/g vs. 63.1 µg/g). This research contributes valuable insights into the dynamics of plastic pollution in coastal environments, particularly in areas influenced by tourism.

Microalgae: A Biological Tool for Removal and Recovery of Potentially Toxic Elements in Wastewater Treatment Photobioreactors.

Potentially toxic elements (PTE) pollution in water bodies is an emerging problem in recent decades due to uncontrolled discharges from human activities. Copper, zinc, arsenic, cadmium, lead, mercury, and uranium are considered potentially toxic and carcinogenic elements that threaten human health. Microalgae-based technologies for the wastewater treatment have gained importance in recent years due to their biomass high growth rates and effectiveness. Also, these microalgae-bacteria systems are cost-effective and environmentally friendly, utilize sunlight and CO2, and simultaneously address multiple environmental challenges, such as carbon mitigation, bioremediation, and generation of valuable biomass useful for biofuel production. Additionally, microalgae possess a diverse array of extracellular and intracellular mechanisms that enable them to remove and mitigate the toxicity of PTE present in wastewater. Therefore, photobioreactors are promising candidates for practical applications in bioremediation of wastewater containing toxic elements. Despite the increasing amount of research in this field in recent years, most studies are conducted in laboratory scale and there is a scarcity of large-scale studies under real and variable environmental conditions. Besides, the limited understanding of the multiple mechanisms controlling PTE biosorption in wastewater containing high organic matter loads and potentially toxic elements requires further studies. This chapter provides a schematic representation of the mechanisms and factors involved in the remediation of potentially toxic elements by microalgae, as well as the main results obtained in recent years.

The relationship between the inhalation bioaccessibility of potentially toxic elements in road dust from a heavily polluted industrial area and the source of their pollution.

One of the sources of chronic exposure to potentially toxic elements (PTE), especially in polluted environments, is the inhalation of resuspended road dust (RD). The aim of this study is to assess the inhalation bioaccessibility of PTE in RD from highly polluted environments from mining/smelting industries and traffic, and to identify any correlations between the bioaccessibility fraction of PTE and the physicochemical characteristics of the particles. RD from the studied area contains extremely high total concentrations of Cr, V, and Mn, which are likely due to pollution from the smelting industry. Additionally, elevated total concentrations of other elements associated with traffic emissions including Zn, Cu, Pb, Sb, and Sn were also measured. The bioaccessibility of PTE was assessed using two synthetic extraction solutions - Gamble's solution (GS) and Artificial Lysosomal Fluid (ALF). The majority of elements showed negligible bioaccessibility in GS. However, quite high inhalation bioaccessibility was observed for Zn, Pb, Sb, Cd, and Mn in the ALF solution, with a mean bioaccessible fraction of 49, 51.5, 41, 50, and 40% respectively. The highest bioavailable fraction was measured for Cd (97%) in a sample collected near a steel production facility and for Pb (95%) in a sample collected near the highway. These results indicate that increased mobility of the elements in inhaled particles occurs only in the case of phagocytosis. The lowest inhalation bioavailability was measured for Cr (mean is 3%). Differential individual particle analysis revealed that about 60% of phases, mostly major (Cr,Ti,V)-bearing metallic alloys, silicates, oxides and sulphides, are stable in ALF solution, while 40% of phases, mostly (Fe,Ca,Mn)-bearing oxides, silicates, sulphides, metals and metallic alloys originating from steel production, ferrochrome, ferrosilicon and vanadium production and from traffic emissions have been heavily corroded or completely dissolved. The study provides valuable information to further assess health hazards from various emission sources.

Relationship between potentially toxic elements and macrophyte communities in the Sava river.

Freshwater ecosystems are at significant risk of contamination by potentially toxic elements (PTEs) due to their high inherent toxicity, their persistence in the environment and their tendency to bioaccumulate in sediments and living organisms. We investigated aquatic macrophyte communities and the concentrations of As, Cu, Cd, Cr, Pb, Zn, Ni and Fe in water and sediment samples to identify a pollution pattern along the Sava River and to investigate the potential impact of these PTEs on the diversity and structure of macrophyte communities. The study, which covered 945 km of the Sava River, showed a downstream increase in sediment concentrations of the analyzed elements. Both species richness and alpha diversity of macrophyte communities also generally increase downstream. Ordinary and partial Mantel tests indicate that macrophyte communities are significantly correlated with sediment chemistry, but only weakly correlated with water chemistry. In the lowland regions (downstream), beta diversity decreases successively, which can be attributed to an increasing similarity of environmental conditions at downstream sites. Species richness is relatively low at sites with low concentrations of Cr, Cd, Fe, and Cu in the sediment. However, species richness increases to a certain extent with increasing element concentrations; as element concentrations increase further, species richness decreases, probably as a result of increased toxicity. Some species that are generally more tolerant to high concentrations of PTEs are: Ceratophyllum demersum, Iris pseudacorus, Najas marina, Butomus umbellatus, Vallisneria spiralis, Potamogeton gramineus and Bolboschoenus maritimus maritimus. Potamogeton perfoliatus and the moss species Cinclidotus fontinaloides and Fontinalis antipyretica have narrow ecological amplitudes in relation to the concentrations of PTEs in the sediment.

Community Perceptions on Health Risks Associated With Toxic Chemical Pollutants in Kwekwe City, Zimbabwe: A Qualitative Study.

Globally, environmental pollution continues to be a significant public health problem, and according to the World Health Organisation, pollution-induced deaths account for 23% of deaths yearly, which could be prevented if people lived in healthier environments. Despite implementing multilateral agreements and international treaties such as the Bamako, Basel, Rotterdam, Minamata, and Stockholm conventions, the United Nations Sustainable Development Goals, and national laws, toxic pollutants remain a serious environmental and public health problem in low-income countries. In the specific context of Kwekwe City, an industrial and mining area in Zimbabwe, where environmental and pollution-induced health problems associated with industries have been widely reported, this study was conducted in close collaboration with the local community. The study aimed to assess community members' perceptions regarding health risks associated with potentially toxic elements and cyanide pollution in Kwekwe City. An explorative cross-sectional study was conducted with key stakeholders and industrial settlements' residents. Face-to-face interviews with key informants and focus group discussions with residents and workers were used to gather data. A thematic approach was utilised in data analysis. Study participants, who played a crucial role in the research process, perceived that industrial pollution principally linked to cyanide, mercury and chromium posed significant environmental and health risks. This participatory approach in risk perception assessment is critical in providing insight into the scope of the problem and formulating intervention strategies. However, given that qualitative study results lack generalisability and replicability, quantitative studies need to be undertaken to determine environmental levels of toxic chemical pollutants as a complementary and validative measure.

Elemental profile of wheat in the las vegas market: Geographic origin discrimination and probabilistic health risk assessment.

This study investigates concentrations of toxic and potentially toxic elements (PTEs) in organic and conventional wheat flour and grains marketed in Las Vegas. Geographic origins of the samples were evaluated using Linear Discriminant Analysis (LDA). Monte Carlo Simulation technique was also employed to evaluate non-carcinogenic risk in four life stages. Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sr, and Zn were determined using inductively coupled plasma mass spectrometry (ICP-MS) following hot block-assisted digestion. Obtained results showed non-significant differences in contents of toxic and PTEs between conventional and organic wheat grains/flour. Using LDA, metal (loid)s were found to be indicative of geographical origin. The LDA produced a total correct classification rate of 95.8% and 100% for US and West Pacific Region samples, respectively. The results of the present study indicate that the estimated non-carcinogenic risk associated with toxic element intakes across the four life stages were far lower than the threshold value (Target Hazard Quotient (THQ) > 1). However, the probability of exceeding the threshold value for Mn is approximately 32% in children aged between 5 and 8 years. The findings of this study can aid in understanding dietary Mn exposure in children in Las Vegas.

Bayesian multivariate receptor model and convolutional neural network to identify quantitative sources and spatial distributions of potentially toxic elements in soils: A case study in Qingzhou City, China.

Determining sources and spatial distributions of potentially toxic elements (PTEs) is a crucial issue of soil pollution survey. However, uncertainty estimation for source contributions remains lack, and accurate spatial prediction is still challenging. Robust Bayesian multivariate receptor model (RBMRM) was applied to the soil dataset of Qingzhou City (8 PTEs in 429 samples), to calculate source contributions with uncertainties. Multi-task convolutional neural network (MTCNN) was proposed to predict spatial distributions of soil PTEs. RBMRM afforded three sources, consistent with US-EPA positive matrix factorization. Natural source dominated As, Cr, Cu, and Ni contents (78.5 %∼86.1 %), and contributed 37.1 %, 61.0 %, and 65.9 % of Cd, Pb, and Zn, exhibiting low uncertainties with uncertainty index (UI) < 26.7 %. Industrial, traffic, and agricultural sources had significant influences on Cd, Pb, and Zn (30.2 %∼61.9 %), with UI < 39.3 %. Hg originated dominantly from atmosphere deposition (99.1 %), with relatively high uncertainties (UI=87.7 %). MTCNN acquired satisfactory accuracies, with R2 of 0.357-0.896 and nRMSE of 0.092-0.366. Spatial distributions of As, Cd, Cr, Cu, Ni, Pb, and Zn were influenced by parent materials. Cd, Hg, Pb, and Zn showed significant hotspot in urban area. This work conducted a new approach exploration, and practical implications for soil pollution regulation were proposed.

Development and testing of an efficient micropollutant monitoring strategy across a large watershed.

In recent decades, extensive monitoring programmes have been conducted at the national, international, and project levels with the objective of expanding our understanding of the contamination of surface waters with micropollutants, which are often referred to as hazardous substances (HS). It has been demonstrated that HS enter surface waters via a number of pathways, including groundwater, atmospheric deposition, soil erosion, and urban systems. Given the ever-growing list of substances and the high resource demand associated with laboratory analysis, it is common practice to quantify the listed pathways based on emission factors derived from temporally and spatially constrained monitoring programmes. The derivation calculations are subject to high uncertainties, and substantial knowledge gaps remain regarding the relative importance of the unique pathways, territories, and periods. This publication presents a monitoring method designed to quantify the unique emission pathways of HS in large geographical areas characterized by differences in land use, population, and economic development. The method will be tested for a wide range of HS (ubiquitous organic and inorganic pollutants, pesticides, pharmaceuticals) throughout small sub-catchments located on tributaries. The results of the test application demonstrate a high diversity of both emission loads and instream concentrations throughout different regions for numerous substances. Riverine concentrations are found to be highly dependent on the flow status. Soil concentration levels of polycyclic aromatic hydrocarbons (PAH) and perfluoroalkyl substances (PFAS) are found to be in proportion, whereas that of potentially toxic elements (PTE) in a reverse relationship with economic development. In many instances, concentration levels are also contingent upon land use. The findings of this study reinforce the necessity for the implementation of harmonised and concerted HS monitoring programmes, which should encompass a diverse range of substances, emission sources, pathways and geographical areas. This is essential for the reliable development of emission factors.

Is the milk we drink safe from elevated concentrations of prioritised heavy metals/metalloids? - A global systematic review and meta-analysis followed by a cursory risk assessment reporting.

Milk has been globally recognised as a comprehensive and vital food source for centuries. However, the presence of heavy metals and metalloids (metal(loid)s) in milk is a global problem. As metal(loid)s are present in the soil due to natural geogenic and various anthropogenic activities, these metal(loid)s are bio-transferred into animal feed, which further results in the presence of metal(loid)s in milk due to bio transfer/accumulation. This systematic review collated information from published literature between 2000 and 2021. It focused on the global issue of metal(loid)s in milk, posing potential health risks. These contaminants enter the food chain through the bio-transfer/accumulation process from soil to animal feed to milk. The key metal(loid)s examined are arsenic (As), mercury (Hg), lead (Pb), and cadmium (Cd). A meta-analysis of 66 selected papers revealed the widespread presence of these contaminants in milk samples globally, with Pb being the most studied (43 %). This research estimated metal(loid)s levels or concentrations as 12.71 (95 % Confidence Interval (CI) = 0.16-25.26), 16.09 (95 % CI = 4.31-27.70), 197.04 (95 % CI = 75.28-318.18), 31.67 (95 % CI = 20.14-43.20) µg/kg (ppb) for As, Hg, Pb, and Cd, respectively using Stata™. The metal(loid) concentrations in milk were within the threshold limits other than Pb and Cd. Some studies in America, Africa, and Asia reported elevated Pb and Cd concentrations, raising health concerns. The simulated Risk Quotients (RQ) and Integrated Risk Quotient (IRQ) values generally remain above one, indicating potential human health risks. Notably, the IRQ value increases with more metal(loid)s consideration. Subgroup analysis indicates low-fat milk contains higher metal(loid)s concentrations. While metal(loid)s concentrations in milk largely comply with safety limits, some regions exhibit concerning concentrations. Therefore, continued surveillance to address potential health risks associated with metal(loid)s in milk is necessary to ensure dairy products' safety.