Search

Drinking water sources with groundwater arsenic (As) contamination face multifaceted challenges in the removal and supply of fresh drinking water resources. To eradicate this problem, bioremediation has evolved to become more effective than other chemical and physical removal processes in its cost-effectiveness, high removal efficiency, and lesser production of secondary by-products or waste. Thus, this study aimed to treat As from aqueous media and to detoxify highly toxic forms of As by the isolated bacteria from As-affected areas. We isolated two new Gram-positive bacteria, which are reported here (Bacillus sp. and Bacillus cereus), with As5+ minimum inhibitory concentrations (MICs) of 4500 mg/L for the Bacillus sp. and 1000 mg/L for Bacillus cereus; meanwhile, for As3+, the MICs are 600 mg/L for both isolates. Bacillus sp. and Bacillus cereus can also effectively convert the highly toxic and easily mobile As3+ to As5+ in aqueous media. This study also demonstrates that these bacteria can remove a significant proportion of As3+ and As5+ (averaging 50% for both) from aqueous media. These As-resistant bacteria from the As-affected area can be used and upscaled for the treatment of As for a safer drinking water supply. [ABSTRACT FROM AUTHOR]

Groundwater vulnerability to geogenic groundwater contamination underlies the complex interplay between various intrinsic geological, hydrogeological, and geochemical characteristics in an aquifer system. Identifying the risks to groundwater quality in this regard is a very engaging process that needs to consider the source and nature of groundwater contamination from the perspective of ongoing external and internal processes within the area/region under study. Arsenic contamination in groundwater has stood out due to its worldwide spread and lethality. It is an established fact that most arsenic sources are predominantly geogenic in nature. Yet, the mechanisms of its mobilization in groundwater appear to be triggered by anthropogenic factors many times. However, the propositions are still being debated and are in an ever-evolving stage. Assessment of groundwater vulnerability to arsenic contamination may thus be considered a potentially valuable management tool for enabling major decisions on preventative groundwater protection, and there is apparently an urgent need to develop robust approaches for the same. One can easily find reviews on groundwater vulnerability per se, but the current review reflects relevant and recent core data compilation/consolidation specifically on arsenic vulnerability assessment. The current work attempts to provide a comprehensive review of the occurrence of arsenic in the subsurface environment, along with the earlier and recent approaches involved in groundwater vulnerability assessment, including mathematical, geostatistical, process-based simulation, and machine learning methods. This paper considers and compares available case studies in this regard and highlights the potential of integrated/hybrid modeling to achieve the best possible outcomes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Arsenic contamination in environmental waters poses global health and environmental risks. This study addresses the urgent need for rapid, selective, and sensitive detection of inorganic arsenic (iAsIII) in environmental samples. Leveraging the unique properties of gold nanoparticles (AuNPs) and the selective binding affinity of homocysteine (Hcy), we developed a novel colorimetric sensor for iAsIII detection. Our investigation elucidates the mechanism by which Hcy modifies AuNPs, enabling the selective detection of iAsIII ions through chelation between amine and carboxyl groups, primarily with the predominant species H2AsO3− at pH 12.0. Our sensor achieves high selectivity (>10‐fold) for iAsIII amid various interfering ions commonly found in environmental samples. Furthermore, we demonstrate exceptional sensitivity in detecting iAsIII, with a low limit of detection (LOD) of 67 nM, aligning with regulatory standards for arsenic concentration in drinking water. The selectivity and sensitivity of our sensor were validated through experiments with various metal ions and real water samples. In conclusion, our study presents a comprehensive understanding of the mechanism, selectivity, and sensitivity of Hcy‐modified AuNPs in detecting iAsIII, offering a versatile nanosensor platform with significant implications for environmental monitoring and public health. [ABSTRACT FROM AUTHOR]

Arsenic, existing in various chemical forms such as arsenate (As(V)) and arsenite (As(III)), demands serious attention in water and environmental contexts due to its significant health risks. It is classified as "carcinogenic to humans" by the International Agency for Research on Cancer (IARC) and is listed by the World Health Organization (WHO) as one of the top 10 chemicals posing major public health concerns. This widespread contamination results in millions of people globally being exposed to dangerous levels of arsenic, making it a top priority for the WHO. Chronic arsenic toxicity, known as arsenicosis, presents with specific skin lesions like pigmentation and keratosis, along with systemic manifestations including chronic lung diseases, liver issues, vascular problems, hypertension, diabetes mellitus, and cancer, often leading to fatal outcomes. Therefore, it is crucial to explore novel, cost-effective, and reliable methods with rapid response and improved sensitivities (detection limits). Most of the traditional detection techniques often face limitations in terms of complexity, cost, and the need for sophisticated equipment requiring skilled analysts and procedures, which thereby impedes their practical use, particularly in resource-constrained settings. Colorimetric methods leverage colour changes which are observable and quantifiable using simple instrumentation or even visual inspection. This review explores the colorimetric techniques designed to detect arsenite and arsenate in water. It covers recent developments in colorimetric techniques, and advancements in the role of nanomaterials in colorimetric arsenic detection, followed by discussion on current challenges and future prospects. The review emphasizes efforts to improve sensitivity, selectivity, cost, and portability, as well as the role of advanced materials/nanomaterials to boost the performance of colorimetric assays/sensors towards combatting this pervasive global health concern. [ABSTRACT FROM AUTHOR]

Arsenic (As) contamination is a serious global concern, polluting our natural resources, including water and soil, and posing a danger to the environment and public health. Arsenic is present in the groundwater of several countries and this contaminated water is used for irrigation, drinking, and food preparation, which poses the greatest threat to public health. Nearly 106 countries are affected by groundwater arsenic contamination and an estimated 230 million individuals worldwide are exposed to its adverse health effects, including increased cancer risks, associated cardiovascular disease and diabetes, skin lesions, neurological effects, kidney damage, and foetal or cognitive-development-related complications. Arsenic is highly toxic and ranked first in the priority list of ATSDR (Agency for Toxic Substances and Disease Registry, 2022) and among the 10 chemicals of major public health concern on the World Health Organization (WHO) list. The maximum permissible level of arsenic in drinking water has been established at 10 µg/L by WHO, as well as by the Environmental Protection Agency (EPA) and European Union (EU). These regulatory standards underscore the gravity of the problem, and actions to prioritise the development of effective detection, mitigation strategies, and collaborative initiatives are necessary. This opinion article covers (i) arsenic footprints—global scenario and impact, (ii) awareness and education and (iii) mitigation approaches (detection and removal strategies) and future perspectives, which collectively will help in controlling and preventing As contamination of our global water resources. Regulatory and legislative bodies and development agencies are crucial for raising awareness and countering this alarming concern by implementing collaborative actions to protect our environment and public health and to provide safe drinking water for all. [ABSTRACT FROM AUTHOR]

Arsenic (As) contamination is a serious global concern, polluting our natural resources, including water and soil, and posing a danger to the environment and public health. Arsenic is present in the groundwater of several countries and this contaminated water is used for irrigation, drinking, and food preparation, which poses the greatest threat to public health. Nearly 106 countries are affected by groundwater arsenic contamination and an estimated 230 million individuals worldwide are exposed to its adverse health effects, including increased cancer risks, associated cardiovascular disease and diabetes, skin lesions, neurological effects, kidney damage, and foetal or cognitive-development-related complications. Arsenic is highly toxic and ranked first in the priority list of ATSDR (Agency for Toxic Substances and Disease Registry, 2022) and among the 10 chemicals of major public health concern on the World Health Organization (WHO) list. The maximum permissible level of arsenic in drinking water has been established at 10 µg/L by WHO, as well as by the Environmental Protection Agency (EPA) and European Union (EU). These regulatory standards underscore the gravity of the problem, and actions to prioritise the development of effective detection, mitigation strategies, and collaborative initiatives are necessary. This opinion article covers (i) arsenic footprints—global scenario and impact, (ii) awareness and education and (iii) mitigation approaches (detection and removal strategies) and future perspectives, which collectively will help in controlling and preventing As contamination of our global water resources. Regulatory and legislative bodies and development agencies are crucial for raising awareness and countering this alarming concern by implementing collaborative actions to protect our environment and public health and to provide safe drinking water for all.

Contamination of groundwater due to arsenic (As) and problems faced by drinking the contaminated water have been identified worldwide. The integration of biogeochemical processes has led to the dissolution of naturally occurring As into the groundwater. The goal of this investigation is mainly to determine the presence of As in drinking water and consequences faced by human beings by drinking such contaminated water. Scope of this issue has not yet undergone a full epidemiological examination in any Indian region. However, in India, little is known about the disease caused by arsenicosis. Therefore, the present study discusses various natural and anthropogenic sources of As in groundwater involving its speciation and mobilization pattern in groundwater. Appropriate review on the issues of As contamination in groundwater has been conducted in various regions across the globe followed by the epidemiology and toxicity mechanisms of As in human beings. Various remediation techniques have been adopted for mitigating the major impact of As contamination depending upon the conventional, modern, and hybrid technologies for removing the As from several regions of India. HIGHLIGHTS A detailed discussion has been done on global groundwater contamination through various sources with ranges, the mechanism of arsenic contamination within the groundwater system, the sources, speciation, and mobility of arsenic.; A detailed discussion has been done on health risks caused by the consuming water contaminated with arsenic.; Effective techniques for the removal are studied.;

This study aimed to develop a geochemical database by thoroughly analyzing groundwater and sediments from coastal aquifers of southwest Bangladesh. Moreover, we investigated the source of sediment deposition and the mechanisms behind the presence of arsenic and salinity in groundwater. The seasonal distribution patterns of arsenic among the shallow and deep coastal aquifers were found to be 45.12 µg/l and 20.65 µg/l during dry and wet seasons, respectively. Moreover, the groundwater salinity distribution ranged from 3262.88 mg/l to 1930.88 mg/l during the dry and wet seasons. Cored sediment samples showed fine to medium sands of 92%, with silt and clay particles. The petrographic study of authigenic and heavy minerals revealed that the mineral grains were subangular to angular, indicating their textural immaturity of coastal sediments. The reactivity of goethite (FeOOH) and siderite (FeCO3) minerals suggests that the aquifers were subjected to slightly oxidized to moderately reducing conditions, with ORP values ranging from +50.40 mv to −149.5 mv. Such redox conditions could potentially result in the enrichment and mobility of arsenic in the groundwater. Although arsenic concentrations in deep aquifers are relatively low, higher salinity values are found in both shallow and intermediate coastal aquifers. [ABSTRACT FROM AUTHOR]

This study investigates the environmental and occupational health risks associated with arsenic (As) and mercury (Hg) contamination in a specific industrial site: a mercury mine site that contains a metallurgical plant within its premises. Utilising a comprehensive sampling and analysis approach, As and Hg concentrations in the soil and air across various zones within the site were assessed. The results revealed elevated levels of both contaminants, particularly in areas proximal to industrial processes such as metal smelting and waste disposal. Risk assessment using the Cancer Risk (CR) and Hazard Index (HI) indices demonstrated significant health hazards that exceed regulatory thresholds, indicating potential carcinogenic effects from As exposure and risks of non-cancerous occupational diseases. Three distinct risk areas were identified based on the CR and HI indices, guiding the formulation of tailored risk management strategies. While some zones may permit limited industrial activities under specific conditions, others require stringent safety measures and specialised personal protective equipment (PPE) due to exceptionally high contaminant concentrations. Overall, the findings underscore the critical need for robust safety protocols and regulatory compliance to mitigate the health risks associated with As and Hg exposure in industrial settings, ensuring the protection of worker health, environmental stewardship, and the promotion of sustainable mining practices. [ABSTRACT FROM AUTHOR]

Background and Objectives: Arsenic, one of the most critical environmental toxins, accumulates in plant and animal organs through root absorption in plants and subsequent ingestion by humans via the food chain or direct consumption of contaminated water. Reports have highlighted the contamination of regional drinking water sources in Bijar city, Kurdistan province, with arsenic and its adverse effects on local residents. Therefore, this research aimed to investigate the distribution of arsenic in the water and soil sources of the region and evaluate the capacity of native pasture plants to absorb and accumulate this element. Materials and Methods: Arsenic concentrations were measured in surface and subsurface waters of a 360 km2 region using the atomic absorptiongraphite furnace method. The distribution of arsenic in the contaminated area was mapped using the ArcGIS program. Three sampling areas with varying pollution intensities (A > B > C) were selected. Soil samples and aerial parts of 13 plant species were collected and analyzed for arsenic concentrations, enabling a comparison of different plant species' ability to absorb arsenic. Results: The intensity of arsenic contamination in surface water, soil, and plants studied in this research exceeded typical concentrations of arsenic in water, soil, and plant sources. Total arsenic concentrations in water samples ranged from 4.5 to 280 μg l-1 and correlated with electrical conductivity, total dissolved solids, and total hardness (P<0.001). Arsenic concentration in the soil of area A (Ali-Abad village) exceeded 2059 μg g-1 of dry soil, with contamination decreasing with distance from area A. A high correlation was observed between the intensity of water and soil pollution (R²=0.84). Arsenic concentrations in the aerial parts of 13 plant species with three replications varied depending on the plant species and the intensity of soil contamination (0 to 47.8 μg g-1). The intensity of soil contamination was on average 27.66 times higher than the amount of arsenic accumulated in the plant, indicating the high resistance of native pasture plants in the region to arsenic toxicity. Conclusion: Field monitoring revealed that 45% of water resources in the sampling areas exceeded the national drinking water standard for arsenic (50 μg l-1), reaching 78% according to the World Health Organization standard (10 μg l-1). Concentrations of parent materials containing arsenic compounds were higher in areas A and B than in area C, with decreasing concentrations further from area A. The sampling region significantly influenced the average arsenic concentration in water and soil samples (P<0.05). Arsenic uptake by the plant samples exceeded typical concentrations (0.1 to 3 μg g-1), with the highest mean arsenic concentrations found in the leaves of Astragalus bisulcatus, Chenopodium album, and Mentha longifolia, accumulating more than 47.8, 35.5, and 22.5 μg g-1, respectively. The study demonstrates heavy contamination of water, soil, and plant resources in the region, with most surface water resources utilized for agricultural irrigation, animal consumption, and occasionally drinking water for village residents. The entry of arsenic into the human body, directly or through the food cycle, poses a severe health risk to the region's residents, necessitating immediate intervention measures. [ABSTRACT FROM AUTHOR]

A major portion of Bangladesh is currently experiencing a scarcity of safe drinking water because of arsenic contamination, high salinity and human-induced pollution. The objectives of this study were to identify locations with a high scarcity of drinking water and suitability of harvesting rainwater. Kriging interpolation algorithms of Geographical Information System (GIS) was employed to identify the probable water scarce zones as well as suitable zones of harvesting rain water from the available data of secondary sources. Statistical methods were employed to cluster, correlate, and regress variables such as rainfall, salinity, and As. The results showed that groundwater quality in the southwestern parts of Bangladesh is saline with high concentration (>10000 μS/cm). On the other hand, the northeastern and southwestern parts of Bangladesh are also vulnerable to arsenic contamination (60 %–97 % of tubewells), compared to other regions. The rainfall zonation map, covering the years 1951–2022, indicated that the Sylhet division had the highest potential for rainfall (ranging from 2600 to 3900 mm). From this study it was demonstrated that Sylhet, Noakhali, Bhola, Barishall, Patuakhali, Bagerhat, and Khulna were identified as suitable places for sustainable rainwater harvesting (RWH). The findings of this study may play significant role towards achieving sustainable potable water supply in vulnerable zones, if they receive attention from policymakers.

The issue of arsenic (As) contamination in the environment has become a critical concern, impacting both human health and ecological equilibrium. Addressing this challenge requires a comprehensive strategy encompassing water treatment technologies, regulatory measures for industrial effluents, and the implementation of sustainable agricultural practices. In this study, diverse strategies were explored to enhance As accumulation in the presence of Acinetobacter bouvetii while safeguarding the host from the toxic effects of arsenate exposure. The sunflower seedlings associated with A. bouvetii demonstrated a favorable relative growth rate (RGR) and net assimilation rate (NAR) even less than 100 ppm of As stress. Remarkably, the NAR and RGR of A. bouvetii-associated seedlings outperformed those of control seedlings cultivated without A. bouvetii in As-free conditions. Additionally, a markedly greater buildup of bio-transformed As was observed in A. bouvetii-associated seedlings (P = 0.05). An intriguing observation was the normal levels of reactive oxygen species (ROS) in A. bouvetii-associated seedlings, along with elevated activities of key enzymatic antioxidants like catalases (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), and peroxidases (POD), along with non-enzymatic antioxidants (phenols and flavonoids). This coordinated antioxidant defense system likely contributed to the improved survival and growth of the host plant species amidst As stress. A. bouvetii not only augmented the growth of the host plants but also facilitated the uptake of bio-transformed As in the contaminated medium. The rhizobacterium's modulation of various biochemical and physiological parameters indicates its role in ensuring the better survival and progression of the host plants under As stress.

Iron (Fe)-based groundwater treatment removes carcinogenic arsenic (As) effectively but generates toxic As-rich Fe oxide water treatment residuals (As WTRs) that must be managed appropriately to prevent environmental contamination. In this study, we apply life cycle assessment (LCA) to compare the toxicity impacts of four common As WTR disposal strategies that have different infrastructure requirements and waste control: (i) landfilling, (ii) brick stabilization, (iii) mixture with organic waste, and (iv) open disposal. The As disposal toxicity impacts (functional unit = 1.0 kg As) are compared and benchmarked against impacts of current methods to produce marketable As compounds via As mining and concentrate processing. Landfilling had the lowest non-carcinogen toxicity (2.0 × 10-3 CTUh), carcinogen toxicity (3.8 × 10-5 CTUh), and ecotoxicity (4.6 × 103 CTUe) impacts of the four disposal strategies, with the largest toxicity source being As emission via sewer discharge of treated landfill leachate. Although landfilling had the lowest toxicity impacts, the stored toxicity of this strategy was substantial (ratio of stored toxicity/emitted As = 13), suggesting that landfill disposal simply converts direct As emissions to an impending As toxicity problem for future generations. The remaining disposal strategies, which are frequently practiced in low-income rural As-affected areas, performed poorly. These strategies yielded ∼3-10 times greater human toxicity and ecotoxicity impacts than landfilling. The significant drawbacks of each disposal strategy indicated by the LCA highlight the urgent need for new methods to recover As from WTRs and convert it into valuable As compounds. Such advanced As recovery technologies, which have not been documented previously, would decrease the stored As toxicity and As emissions from both WTR disposal and from mining As ore.

Among heavy metals, arsenic contamination in water resources is a major concern due to its harmful effects on human health as slow poison behaviour affecting many states of India and at global level. The present study is about efficiency of Scolecite (CaAl2Si3O10.3H2O), a natural zeolite mineral, to remove arsenic contamination from water. The arsenic-contaminated water samples were collected from both industrial areas and non-industrial areas which include Singrauli industrial sites of Madhya Pradesh/Uttar Pradesh, Jalangi Block and various thermal power station areas of West Bengal, Kaudikasa-Rajnandgaon district of Chhattisgarh and Kakching area of Manipur. After conducting rigorous experimental studies, it was observed that the collected water samples had been reduced up to below 10 ppb within the permissible limit of WHO in 7 days with different quantities of scolecite (as 0.5 g/50 ml, 2.5 g/50 ml, 5 g/50 ml and 10 g/100 ml). The reduction of arsenic and the absorbing properties were identified as negative charge developed on the crystal face of Si3Al3 in scolecite. The XRD analysis of filtrate, which remained after filtration of samples prior to chemical analysis for arsenic concentration, is that specific hkl faces (i.e. 111, 040, 132, 400 and 240) are more affected in increase of pH in scolecite-treated water samples and hence play a major role in arsenic removal. The adsorption efficiency of arsenic (As) from water samples was predicted in the present study using an artificial neural network (ANN) model and perceived that the smallest quantity of scolecite may reduce higher amount of As in proportionate water samples. [ABSTRACT FROM AUTHOR]

This educational exploration delves into the complex intersections of these two realms, aiming to unravel the nuanced relationship between environmentally conscious chemical practices and the pressing challenge of arsenic contamination in groundwater. As we navigate the intricate landscape of sustainable development, this study seeks to provide valuable insights that not only shed light on the scientific intricacies involved but also contribute to the formulation of informed strategies and solutions. Through a holistic examination of the multifaceted facets of Green Chemistry and arsenic-induced groundwater pollution, this research endeavors to carve a path towards a more sustainable and resilient future. For an extended period, the utilization of green chemistry (GC) has demonstrated that employing a fundamental scientific methodology and advanced practices can enhance the safe production for human life while minimizing environmental disturbances. To achieve this, progress has been made in scientific processes within the realms of designing safer reagents and solvents, advancing catalysis, and potentially developing renewable feed stocks. To attain greater accomplishments, contemporary chemists are now being educated and trained in a broader understanding of green chemistry, emphasizing increased awareness of both human and environmental impacts. Nevertheless, the global emphasis on sustainable development has posed a challenge for green chemistry educators to instruct students in assessing the intricate factors of green chemistry, including societal sustainability considerations. This paper reviews courses and programs that aim to fulfill these objectives, along with assessment methods used to evaluate student outcomes in green chemistry courses. The global food supply has significantly expanded due to the discovery of hybrid varieties, improved cultivation methods, better seeds, and the use of pesticides, herbicides, and fertilizers. [ABSTRACT FROM AUTHOR]

The coast of Espírito Santo state (Southeast Brazil) is recognized for its environmental arsenic (As) enrichment and, over the years, mining operations have potentialized it. We aimed to evaluate the effect of Rio Doce discharge on As inputs and the role of iron ore tailings from the Fundão dam disaster in enhancing As contamination in the marine sediment. Two scenarios were evaluated: Predisaster and Postdisaster; dry and wet conditions were considered in each period. High As concentrations were found in the Predisaster (28.44 ± 13.53 µg g−1), but a significant increase in As was remarkable during the Postdisaster in the wet season, one year after the disaster (maximum of 58.39 µg g−1; geoaccumulation index (Igeo) Class 3, moderately severe pollution). On that occasion, iron (Fe) oxy‐hydroxides from tailings were remobilized from the Rio Doce channel and deposited on the continental shelf bottom. Therefore, chemical interactions among Fe, As, and carbonates were enhanced, resulting in As and Fe coprecipitation and the trapping by carbonate adsorption. Rio Doce discharge seems to be the main factor in As inputs to the inner continental shelf when flooding do not occur previously in samplings, which allows further dispersion of contaminants, although this hypothesis should be tested further. Integr Environ Assess Manag 2024;20:159–168. © 2023 SETAC Key Point: Arsenic contamination of marine sediments was studied before and after the rupture of a mining tailings dam (Fundão dam disaster).Arsenic concentrations increased from moderate (Predisaster) to moderately severe pollution levels (Postdisaster) one year after the disaster.Iron oxy‐hydroxide inputs from iron ore tailings probably explain the accumulation of As in sediments by coprecipitation of As and Fe and deposition by carbonate adsorption.River discharges did not increase As concentrations in sediment during the initial stages after the disaster (twenty days and two months after). [ABSTRACT FROM AUTHOR]

High concentrations of arsenic in soil and plant systems are a threat to human health and ecosystems. The levels of phosphate ions in the soil strongly influence the soil efficacy and arsenic absorption by plants. This study investigated the effects of phosphate-solubilizing fungi (PSF) on environmental factors and structural changes in microbial community in soils contaminated with arsenic. Four experimental groups were created: control (CK), Penicillium GYAHH-CCT186 (W186), Aspergillus AHBB-CT196 (W196), and Penicillium GYAHH-CCT186 + Aspergillus AHBB-CT196 (W186 + W196), with Pakchoi (Brassica chinensis L.) as the test plant. Analysis of altered nutrient levels, enzyme activities and microbial community structure in the soil as well as the growth and physiological characteristics of Pakchoi, revealed a significant increase in the available phosphorus (AP), organic matter (OM), cation exchange capacity (CEC) and available arsenic (AAs) content of the soil following W186 + W196, W196 and W186 treatments. All experimental treatments enhanced the activity of soil β-glucosidase (β-GC) and soil catalase (S-CAT). W186 + W196 and W196 treatments significantly enhanced soil acid phosphatase (S-ACP) activity. Besides, W186 + W196 treatment significantly induced dehydrogenase (S-DHA) activity. Further, of the treatment with PSF increased the fresh weight, root length, plant height and chlorophyll levels while decreasing the arsenic accumulation in Pakchoi. Exposure to PSF also increased the activity of Ascomycota, Basidiomycota, Chytridiomycota, unclassified_Fungi, Mortierellomycota, Cryptomycota and Rozellomycota in the soil. The relative abundance of Ascomycota, Basidiomycota, and Mortierellomycota was positively correlated with the available nutrients (except iron) in the soil as well as enzyme activities. Consequently, the PSF improved the quality of soil and the safety of Pakchoi, suggesting that PSF can be utilized for the remediation of arsenic-contaminated soil. [ABSTRACT FROM AUTHOR]

This study investigated the concentrations of arsenic (As) in soil and plant biomass from the Barak Valley in South Assam, India. Soil samples showed concentrations ranging from 6.06 ± 0.84 mg/kg to 18.61 ± 1.52 mg/kg, with an average of 10.60 ± 3.15 mg/kg, 41.67% of the sample exceeding uncontaminated ranges (0.1–10 mg/kg). Ecological risk assessments such as contamination factors, pollutant load index, geo‐accumulation index, and anthropogenicity identified varying contamination levels across sampling points. A total of 24 plant species were collected, ferns (two species), shrubs (five species), grass (six species), and herb (11 species). The concentration of As in different plants types decreased in the order of fern (393.45 ± 159.63 mg/kg) > shrub (20.48 ± 7.25 mg/kg) > herb (17.92 ± 13.75 mg/kg) > grass (14.98 ± 13.80 mg/kg). Plant species, namely Pityrogramma calomelanos, Christella dentata, Mimosa pudica, Chromolaena odorata, Leucas aspera, Persicaria decipiens, Melastoma malabathricum, and Clerodendrum infortunatum, accumulated higher concentrations of As in their above‐ground parts compared to roots and were categorized as tolerant accumulators (TF > 1). By incorporating these plant species into phytoextraction strategies, the region can benefit from their unique properties and abilities to effectively remediate arsenic‐contaminated sites, ultimately improving the affected areas' environmental and human health conditions. [ABSTRACT FROM AUTHOR]

Arsenic is a human carcinogen and contributes to the incidences of cancer, diabetes, and skin diseases in the exposed populations. Therefore, its occurrence in drinking water is of public health concern worldwide, especially in the Tano, Pra, and Ankobra River Basins in Ghana. The metasediments and metavolcanic formations which underlie these basins (42,092.5 km2) host arsenic sulphide minerals that are a source of arsenic contamination of the weathered and fractured aquifers that serve as drinking water supply to most of the population (∼9.8 million), especially in the rural areas. A random forest machine learning method and partial dependence plots were applied to maps of spatially continuous environmental factors (fault density, surface bulk density, coarse fragment and soil pH; and sub-surface silt and soil pH) and hydrochemical variables, respectively, and arsenic measurements from wells (n = 229) which included 57 new datasets of which 7.86 % exceeded the 10 µg/L to develop arsenic prediction models for the basins at thresholds of 1 µg/L, 5 µg/L, and 10 µg/L. Fault density and coarse fragments were more reliable contributors to the models. A partial dependence plot and Spearman's rank correlation analysis showed a significant positive correlation (p < 0.01) between arsenic enrichment and HCO3−, pH, Fe, and Mn, except NO3− in groundwater. Arsenic hotspots occurred in urban districts in the Ashanti Region and known gold-mining areas in Nzema, Obuasi, Prestea, and Tarkwa. Spatially, arsenic contamination in groundwater covered 49.44 % of the land area of the basins. By cross-referencing population density estimates and the arsenic hazard map,15.8 % of the population is exposed to arsenic-contaminated groundwater in the basins. The hazard model will facilitate efforts to reduce rural poverty and protect public health by delivering potable water in Ghana. The hazard models apply to crystalline terrain in other sub-Saharan African countries.

One of the biggest environmental worries in the world today is the risk of arsenic (As) contamination in groundwater. The Atomic Absorption Spectrometer (AAS) was used in this work to assess the As content in groundwater samples from 38 shallow (27 m) tubewells in northwest Bangladesh to determine the existing situation, potential source(s), and likely health risk of As and other important water quality parameters. The range of arsenic concentrations (μgL−1) was troublesome and greater than the WHO recommended level for drinking water, ranging from 0.50 to 164 (mean ± SD: 20.22 ± 36.46). In groundwater, the concentrations of Fe, and Mn vary from 0.04 to 52.75 mgL−1 (mean ± SD: 4.23 ± 9.68), and 0.23 to 3.27 mgL−1 (mean ± SD: 1.10 ± 0.67). The obtained groundwater samples have pH values ranging from 5.9 to 7.1, which indicates a somewhat acidic to neutral character. Major cations have an average abundance that is as follows: Ca2+ > Mg2+ > Na+ > K+, while major anions have an average abundance that is as follows: HCO3− > Cl− > SO42− > NO3−; Ca2+ and HCO3− are the main cation and anion, respectively. The groundwater in the Rajarampur village was deemed unfit for drinking or irrigation based on analyses of water quality performed using the entropy water quality index. The Ca–HCO3 type of water, in which Ca2+ and HCO3− are the main positive ions and negative ions, is suggested by the Piper tri-linear diagram. It was discovered that silicate weathering regulates the hydro-geochemical activities in groundwater using a bi-variate examination of several hydro-chemical variables. Four major clusters were observed for the water sample. According to reductive dissolution processes and principal component analysis, the arsenic in groundwater is geogenic in origin. Arsenic is discharged from sediment to groundwater by reductive dissolution of FeOOH and MnOOH, as shown by the modest connection between As, Fe, and Mn. The United Nations Environmental Protection Agency's (USEPA) suggested value for probable cancer risk assessment was 10−6, however the probable cancer risk assessment found a higher value, indicating that the population in the study region was at high risk for cancer. Remedial measures for arsenic mitigation include removing arsenic from groundwater after it is extracted, searching for alternative aquifers, and implementing various water-supply technologies such as dugwells, deep tubewells, pond-sand filters, and rainwater harvesting systems.

Agricultural soils naturally enriched with Arsenic (As) represent a significant global human health risk. In the present investigation, a series of pot experiments were conducted to study the efficacy of three levels of Yellow Gypsum (YG) application on bioavailability of As to kharif groundnut followed by boro-rice grown under 17 different levels of soil As contamination for two consecutive years. The results revealed that application of YG @ 60 kg ha−1 effectuated the lowest soil As content and the highest percent decline in soil extractable As at pegging (9.42 mg kg−1 and 9.81%) and harvesting (8.81 mg kg−1 and 11.85%) in groundnut, maximum tillering (7.52 mg kg−1 and 16.95%) and harvesting (6.77 mg kg−1 and 19.85%) in boro-rice respectively. It was also observed that irrespective of its level, the extractable As content of soil decreased significantly (P

Abstract Metalloid pollution, including arsenic poisoning, is a serious environmental issue, plaguing plant productivity and quality of life worldwide. Biochar, a carbon-rich material, has been known to alleviate the negative effects of environmental pollutants on plants. However, the specific role of biochar in mitigating arsenic stress in maize remains relatively unexplored. Here, we elucidated the functions of biochar in improving maize growth under the elevated level of sodium arsenate (Na2AsO4, AsV). Maize plants were grown in pot-soils amended with two doses of biochar (2.5% (B1) and 5.0% (B2) biochar Kg−1 of soil) for 5 days, followed by exposure to Na2AsO4 ('B1 + AsV'and 'B2 + AsV') for 9 days. Maize plants exposed to AsV only accumulated substantial amount of arsenic in both roots and leaves, triggering severe phytotoxic effects, including stunted growth, leaf-yellowing, chlorosis, reduced photosynthesis, and nutritional imbalance, when compared with control plants. Contrariwise, biochar addition improved the phenotype and growth of AsV-stressed maize plants by reducing root-to-leaf AsV translocation (by 46.56 and 57.46% in ‘B1 + AsV’ and ‘B2 + AsV’ plants), improving gas-exchange attributes, and elevating chlorophylls and mineral levels beyond AsV-stressed plants. Biochar pretreatment also substantially counteracted AsV-induced oxidative stress by lowering reactive oxygen species accumulation, lipoxygenase activity, malondialdehyde level, and electrolyte leakage. Less oxidative stress in ‘B1 + AsV’ and ‘B2 + AsV’ plants likely supported by a strong antioxidant system powered by biochar-mediated increased activities of superoxide dismutase (by 25.12 and 46.55%), catalase (51.78 and 82.82%), and glutathione S-transferase (61.48 and 153.83%), and improved flavonoid levels (41.48 and 75.37%, respectively). Furthermore, increased levels of soluble sugars and free amino acids also correlated with improved leaf relative water content, suggesting a better osmotic acclimatization mechanism in biochar-pretreated AsV-exposed plants. Overall, our findings provided mechanistic insight into how biochar facilitates maize’s active recovery from AsV-stress, implying that biochar application may be a viable technique for mitigating negative effects of arsenic in maize, and perhaps, in other important cereal crops. Graphical Abstract

Drinking water sources with groundwater arsenic (As) contamination face multifaceted challenges in the removal and supply of fresh drinking water resources. To eradicate this problem, bioremediation has evolved to become more effective than other chemical and physical removal processes in its cost-effectiveness, high removal efficiency, and lesser production of secondary by-products or waste. Thus, this study aimed to treat As from aqueous media and to detoxify highly toxic forms of As by the isolated bacteria from As-affected areas. We isolated two new Gram-positive bacteria, which are reported here (Bacillus sp. and Bacillus cereus), with As5+ minimum inhibitory concentrations (MICs) of 4500 mg/L for the Bacillus sp. and 1000 mg/L for Bacillus cereus; meanwhile, for As3+, the MICs are 600 mg/L for both isolates. Bacillus sp. and Bacillus cereus can also effectively convert the highly toxic and easily mobile As3+ to As5+ in aqueous media. This study also demonstrates that these bacteria can remove a significant proportion of As3+ and As5+ (averaging 50% for both) from aqueous media. These As-resistant bacteria from the As-affected area can be used and upscaled for the treatment of As for a safer drinking water supply.

Arsenic, existing in various chemical forms such as arsenate (As(V)) and arsenite (As(III)), demands serious attention in water and environmental contexts due to its significant health risks. It is classified as “carcinogenic to humans” by the International Agency for Research on Cancer (IARC) and is listed by the World Health Organization (WHO) as one of the top 10 chemicals posing major public health concerns. This widespread contamination results in millions of people globally being exposed to dangerous levels of arsenic, making it a top priority for the WHO. Chronic arsenic toxicity, known as arsenicosis, presents with specific skin lesions like pigmentation and keratosis, along with systemic manifestations including chronic lung diseases, liver issues, vascular problems, hypertension, diabetes mellitus, and cancer, often leading to fatal outcomes. Therefore, it is crucial to explore novel, cost-effective, and reliable methods with rapid response and improved sensitivities (detection limits). Most of the traditional detection techniques often face limitations in terms of complexity, cost, and the need for sophisticated equipment requiring skilled analysts and procedures, which thereby impedes their practical use, particularly in resource-constrained settings. Colorimetric methods leverage colour changes which are observable and quantifiable using simple instrumentation or even visual inspection. This review explores the colorimetric techniques designed to detect arsenite and arsenate in water. It covers recent developments in colorimetric techniques, and advancements in the role of nanomaterials in colorimetric arsenic detection, followed by discussion on current challenges and future prospects. The review emphasizes efforts to improve sensitivity, selectivity, cost, and portability, as well as the role of advanced materials/nanomaterials to boost the performance of colorimetric assays/sensors towards combatting this pervasive global health concern.

Abstract Groundwater is one of the world’s most important sources of fresh drinking water. Various contaminants mix with groundwater and alter its natural composition, such as arsenic. This study aimed to ascertain the present condition of arsenic concentration, its spatial pattern, and its relationship with tube well depth in the Gangni Union in the Chuadanga district of Bangladesh. Additionally, the study tried to assess the associated noncarcinogenic health risks imposed by oral ingestion of arsenic. Systematic sampling was used to collect water samples $$(n=100)$$ ( n = 100 ) along with depth information from the sample tube wells. Water samples were analyzed with the pre-calibrated Hach EZ, Dual-Range Arsenic Test Kit (Range: 0.00–0.5 mg/l). Both geostatistical (spatial autocorrelation, Hotspot analysis, and IDW) and statistical (descriptive and correlation statistics) methods were used. The resultant arsenic content of the samples tested ranges from 0.0004 (mg/l) to 0.10 (mg/l). Arsenic levels in almost 42% of the samples exceeded the WHO standard, 21% exceeded the Bangladesh standard, and 37% were within the tolerable standard. Geostatistical analysis shows that approximately 63% of the total area is arsenic contaminated. Furthermore, hotspot analysis reveals that the northeastern and southeastern parts of the study area are more arsenic-contaminated than the other parts. Noncarcinogenic health risk assessment shows that children have a higher average daily dose (ADD) range (8.33E-06-0.00181) than adults (2.78E-06-0.0006). Similarly, the hazard quotient (HQ) value is also higher for children (0.0277–6.033) than for adults (0.0092–2.011). The result of Pearson’s correlation coefficient, r (98) = − 0.7580, p = 0.000, shows a negative linear relationship between concentration values and depth, meaning that increasing depth will reduce arsenic contamination from tube well water.

Metalloid pollution, including arsenic poisoning, is a serious environmental issue, plaguing plant productivity and quality of life worldwide. Biochar, a carbon-rich material, has been known to alleviate the negative effects of environmental pollutants on plants. However, the specific role of biochar in mitigating arsenic stress in maize remains relatively unexplored. Here, we elucidated the functions of biochar in improving maize growth under the elevated level of sodium arsenate (Na2AsO4, AsV). Maize plants were grown in pot-soils amended with two doses of biochar (2.5% (B1) and 5.0% (B2) biochar Kg−1 of soil) for 5 days, followed by exposure to Na2AsO4 ('B1 + AsV'and 'B2 + AsV') for 9 days. Maize plants exposed to AsV only accumulated substantial amount of arsenic in both roots and leaves, triggering severe phytotoxic effects, including stunted growth, leaf-yellowing, chlorosis, reduced photosynthesis, and nutritional imbalance, when compared with control plants. Contrariwise, biochar addition improved the phenotype and growth of AsV-stressed maize plants by reducing root-to-leaf AsV translocation (by 46.56 and 57.46% in 'B1 + AsV' and 'B2 + AsV' plants), improving gas-exchange attributes, and elevating chlorophylls and mineral levels beyond AsV-stressed plants. Biochar pretreatment also substantially counteracted AsV-induced oxidative stress by lowering reactive oxygen species accumulation, lipoxygenase activity, malondialdehyde level, and electrolyte leakage. Less oxidative stress in 'B1 + AsV' and 'B2 + AsV' plants likely supported by a strong antioxidant system powered by biochar-mediated increased activities of superoxide dismutase (by 25.12 and 46.55%), catalase (51.78 and 82.82%), and glutathione S-transferase (61.48 and 153.83%), and improved flavonoid levels (41.48 and 75.37%, respectively). Furthermore, increased levels of soluble sugars and free amino acids also correlated with improved leaf relative water content, suggesting a better osmotic acclimatization mechanism in biochar-pretreated AsV-exposed plants. Overall, our findings provided mechanistic insight into how biochar facilitates maize's active recovery from AsV-stress, implying that biochar application may be a viable technique for mitigating negative effects of arsenic in maize, and perhaps, in other important cereal crops. Highlights: Maize developed significant growth defects under excessive arsenate (AsV) stress. Biochar addition decreased root AsV uptake and root-to-leaf AsV translocation. Biochar protected photosynthetic rate and pigment levels from AsV -stress. Biochar reduced AsV-caused oxidative damage by strengthening antioxidant defense. Biochar boosted osmoprotectant levels and nutrient uptake in AsV-stressed maize. [ABSTRACT FROM AUTHOR]

Environmental context: Arsenic (As) contamination in agricultural soil threatens safe agricultural production. Therefore, an ex situ magnet-assisted soil washing, using different types of nanoscale zerovalent iron was tested as a remediation option in soil restoration. Uncoated nanoparticles was the best tested option, with As removal at 45.5% and the nanoparticles were reusable up to four times. Rationale: Arsenic (As) contamination in agricultural soil threatens safe food and medicinal herb production for millions of people. Methodology: Therefore, ex situ magnet-assisted soil washing of metal-contaminated soil using bare nanoscale zerovalent iron (NZVI) is proposed as a novel remediation alternative. Conceptually, metal-contaminated soil is mixed with water and bare NZVI, and metals in the soil are transferred to the bare NZVI. The metal-sorbed NZVI is then retrieved from the soil slurry through magnetic separation, leaving behind treated soil. This study evaluated if advanced surface modification can improve ex situ soil restoration efficacy including polymeric coating and sulfidation of NZVI, proven beneficial in situ NZVI application. Sulfur and carboxymethylcellulose (CMC) at various S/Fe and CMC/NZVI ratios were used to modify NZVI via sulfidation and physisorption. Result: Results revealed that sulfidised NZVI (S-NZVI) performed poorer (41.0%) than bare NZVI (45.5%) in As removal, even at the optimised S/Fe ratio of 0.31. This could be due to acid release via oxidative dissolution of FeS[sub 2] on the S-NZVI surface driven by O[sub 2]. The incidental acid-dissolved NZVI sorption sites decreased As removal efficacy. Similarly, CMC-modified NZVI failed to improve As removal efficacy (11.0%) because it reduced NZVI reactivity and blocked As accessibility to NZVI sorptive sites. Discussion: Nevertheless, S-NZVI and CMC-modified NZVI promoted non-phytoavailable As fractions in the treated soil. Overall, bare NZVI performed the best for As removal but moderately transformed As into more non-phytoavailable fractions. Bare NZVI can be reused for four cycles of soil washing. In every case, mobile As in treated soil was lower than the maximum contamination level. [ABSTRACT FROM AUTHOR]

This study aimed to develop a geochemical database by thoroughly analyzing groundwater and sediments from coastal aquifers of southwest Bangladesh. Moreover, we investigated the source of sediment deposition and the mechanisms behind the presence of arsenic and salinity in groundwater. The seasonal distribution patterns of arsenic among the shallow and deep coastal aquifers were found to be 45.12 µg/l and 20.65 µg/l during dry and wet seasons, respectively. Moreover, the groundwater salinity distribution ranged from 3262.88 mg/l to 1930.88 mg/l during the dry and wet seasons. Cored sediment samples showed fine to medium sands of 92%, with silt and clay particles. The petrographic study of authigenic and heavy minerals revealed that the mineral grains were subangular to angular, indicating their textural immaturity of coastal sediments. The reactivity of goethite (FeOOH) and siderite (FeCO3) minerals suggests that the aquifers were subjected to slightly oxidized to moderately reducing conditions, with ORP values ranging from +50.40 mv to −149.5 mv. Such redox conditions could potentially result in the enrichment and mobility of arsenic in the groundwater. Although arsenic concentrations in deep aquifers are relatively low, higher salinity values are found in both shallow and intermediate coastal aquifers.

Groundwater is one of the world's most important sources of fresh drinking water. Various contaminants mix with groundwater and alter its natural composition, such as arsenic. This study aimed to ascertain the present condition of arsenic concentration, its spatial pattern, and its relationship with tube well depth in the Gangni Union in the Chuadanga district of Bangladesh. Additionally, the study tried to assess the associated noncarcinogenic health risks imposed by oral ingestion of arsenic. Systematic sampling was used to collect water samples (n = 100) along with depth information from the sample tube wells. Water samples were analyzed with the pre-calibrated Hach EZ, Dual-Range Arsenic Test Kit (Range: 0.00–0.5 mg/l). Both geostatistical (spatial autocorrelation, Hotspot analysis, and IDW) and statistical (descriptive and correlation statistics) methods were used. The resultant arsenic content of the samples tested ranges from 0.0004 (mg/l) to 0.10 (mg/l). Arsenic levels in almost 42% of the samples exceeded the WHO standard, 21% exceeded the Bangladesh standard, and 37% were within the tolerable standard. Geostatistical analysis shows that approximately 63% of the total area is arsenic contaminated. Furthermore, hotspot analysis reveals that the northeastern and southeastern parts of the study area are more arsenic-contaminated than the other parts. Noncarcinogenic health risk assessment shows that children have a higher average daily dose (ADD) range (8.33E-06-0.00181) than adults (2.78E-06-0.0006). Similarly, the hazard quotient (HQ) value is also higher for children (0.0277–6.033) than for adults (0.0092–2.011). The result of Pearson's correlation coefficient, r (98) = − 0.7580, p = 0.000, shows a negative linear relationship between concentration values and depth, meaning that increasing depth will reduce arsenic contamination from tube well water. [ABSTRACT FROM AUTHOR]

As-containing chemical weapons (CWs) and their degraded products pose a great threat to the environment and to human health. In this study, concentration and distribution characteristics, source identification, and health risk assessments were determined for As, Cr, Ni, Cu, Zn, Cd and Pb in environmental samples from Lianhuapao (LHP), a typical site of Japanese abandoned chemical weapons (JACWs) in China. The results show that the concentration levels of As, Cr and Ni in the LHP soils are abnormally high, with 69.57%, 83.33% and 91.67%, respectively, of the total sample exceeding the risk screening values for soil contamination of agricultural land. As levels in water samples were generally within safety limits, with the exception of perched water in the core contamination area. In the study area, none of the dominant plant species were enriched with As, except for the Pteris vittata L. Pentavalent arsenic was found to be the predominant arsenic species in the topsoil and water samples. Source identification using statistical approaches indicated that the concentrations of As, Pb, Cu, Cd and Zn are likely influenced by JACWs, while Cr and Ni levels may be related to the natural weathering process. The total concentrations of As, Cr and Ni showed a significant degree of contamination, but only As displayed high potential ecological risk. The calculated indexes of health risk evaluation strongly indicate an unacceptable carcinogenic risk (1E−04) to children, and higher non-carcinogenic risk, relative to that of adults. Our data indicate that the health risk from the resulting As contamination is still a cause for concern, although the JACWs were excavated decades ago from these soils. [ABSTRACT FROM AUTHOR]

The health impact of groundwater arsenic contamination shall remain partially understood while its psychological aspects are not studied. So, this correlational survey research explored mental health as a function of perceived social support in arsenic-induced cancer (AIC), which is highly prevalent in the middle Gangetic plain. Mental health inventory and multidimensional scale of perceived social support were used to assess mental health (MH) and perceived social support (PSS) respectively in 77 AIC patients. Findings show significant impact of PSS on MH in the arsenic-affected regions. PSS from significant others have strong impact on overall MH. Perception of reality was predicted by PSS from family while global PSS predicted two dimensions of MH, i.e. positive self-evaluation and environmental mastery. This baseline study suggests that global PSS and that from family and significant others is important and has a strong impact on MH of this population. These findings would help early identification and/or psychological intervention (from non-government organizations, oncology social workers/researchers, and policy makers) to promote better health and well-being in this arsenic-affected population. HIGHLIGHTS Ground water arsenic contamination in the Indo Gangetic plain bears health risk beyond physiological consequences.; Mental health is explored in arsenic induced cancer (AIC) patients.; Perceived social supports from friends, family and significant others have protective impact on mental health.; Psychological aspects of As exposure calls for policy making and timely intervention to achieve the UN-SDG-3.;

Macroalgae bioremediation is a potential way to deal with the escalating problem of arsenic contamination. The results of this study demonstrate that the arsenic content in wastewater treated by Oedogonium intermedium decreases by 32% from 1.13 ± 0.01 to 0.77 ± 0.03 ppb. Then, supercritical carbon dioxide (SC‐CO2) extraction was employed to isolate lipids from O. intermedium. Response surface methodology based on the Box‐Behnken design was carried out to optimize the SC‐CO2 extraction conditions of pressure (200–400 bar), temperature (30–50 °C), and extraction time (30–90 min). The optimal conditions from the model are predicted as 301.95 bar, 41.3 °C, and 30.53 min with 3.24 % lipid yield, 61.30 % PUFA ratio, and 0.106 µg g−1 of arsenic content, respectively. [ABSTRACT FROM AUTHOR]

This study deals with arsenic distribution in groundwater, soil and edible vegetables in the densely populated area of the Versilia Plain (Tuscany region, Italy), addressing potential impacts on people's health. The data revealed high As concentrations in some domestic irrigation wells, exceeding 1200 µg/L. The average As concentration in topsoil and subsoil was 39 and 46 mg/kg, respectively, with the highest concentration reaching about 200 mg/kg. Arsenic concentrates in plant roots compared with the edible parts; in tomato fruits, black cabbage leaves and edible leek parts As reached about 0.2 mg/kg, 0.4 mg/kg and 3 mg/kg, respectively. Geochemical and hydrostratigraphic data suggest that As in soils and alluvial sediments originated from mineralized and historical upstream mining areas. The exposure routes for both non-carcinogenic and carcinogenic risk assessment here considered include soil ingestion, dermal absorption, soil dust inhalation and vegetable consumption. For non-carcinogenic and carcinogenic effects, the hazard was higher than the acceptance threshold. The calculated soil screening levels resulted even lower than the guideline soil-concentration imposed by Italian regulations, and this poses an issue on the actual meaning of arsenic regulatory thresholds. [ABSTRACT FROM AUTHOR]

Lakes provide a wide range of ecosystem services that are increasingly at risk because of multiple anthropogenic pressures. Santa María del Oro crater lake lies in rural northwest Mexico and is of interest for global change studies and as a natural resource that sustains the economies of local communities. Temporal trends of trace element (As, Co, Cr, Cu, Ni, Pb, V, and Zn) concentrations over the past century were assessed in four 210Pb-dated sediment cores, under the hypothesis that recent anthropogenic activities have promoted increasing trace element inputs. Data were analyzed within three periods: (1) pre-1900s, from which background levels were estimated, (2) pre-1950, and (3) post-1950. Trace element provenance was determined through a chemometric approach. Most trace element concentrations varied little in the past ~ 100 years, with no Co, V, and Zn enrichment, and minor enrichment by Cr, Cu, Ni and Pb in a few sections of the cores collected from the deepest locations, within the hypolimnion, and by Pb along the shallowest core. In contrast, As enrichment in the deep cores reached moderately severe levels during the post-1950 period. Cobalt, Pb, V, and Zn input to the lake was related to terrigenous sources. Lead enrichment was mainly anthropogenic (the shallow coring site is close to human settlements). Copper and Cr variability were mostly the result of diagenetic reactions. Arsenic enrichment, however, was attributed to biogeochemical cycling processes, likely exacerbated by drought conditions and enhanced calcite precipitation. Contradicting our hypothesis, recent anthropogenic impact on the lake´s environmental quality was small. However, a preliminary assessment, based on international guidelines, indicated that As, Cr, and Ni concentrations could be harmful to benthic biota, even at background levels. High As concentrations could affect the aquatic food web and human health, the latter through fish consumption. Given predictions for increasing droughts in the area, which induce greater evaporation and lower water levels, this issue could worsen in the future. Further studies on As contamination in the lake are needed to better understand potential hazards and enhance response capacity. Such data must be part of conservation efforts and should be integrated into management policies to ensure the lake's sustainability. [ABSTRACT FROM AUTHOR]

Globally, potentially toxic elements (PTEs) are regarded as an important group of pollutants for the wider environment because of their intrinsic toxicity and probable accumulation in the soil-water-plant system. In this regard, this study assessed the pollution levels and probable human health risks of PTEs in the soil-water-plant system in the Bolkar mining district of the Niğde Province in south-central Turkey. Pollution assessment using contamination factor, enrichment factor, index of geoaccumulation, and soil pollution index reveals moderate to extremely high pollution of PTEs in the soil, exposing the soils to extreme toxicity levels. The areas that fall under the toxic to extremely toxic categories are in proximity to the ore slags and agricultural lands towards the central and southern domains of the study area. The water hazard index (WHI) values indicate that 100% of the samples collected in both winter and fall seasons are of extreme toxicity (WHI > 15). Arsenic is the dominant contaminant among the PTEs in the soil and water samples. The bioconcentration factor values of the PTEs in most of the fruit plants are > 1, indicating very high levels of element transfer from the soil and water to the plants. The probabilistic human health risk assessment involved exposure to arsenic in groundwater (a major pathway to humans) since it is the only carcinogenic element in this study. The estimated daily intake of arsenic-contaminated water exceeds the safe limit of 5 × 10−8 mg/kg/day. About 33.3% and 55.6% of the groundwater samples have higher hazard quotient and carcinogenic risk values of arsenic in the winter and fall seasons, respectively. This implies that the people are more exposed to the carcinogenic effects of drinking arsenic-contaminated water. [ABSTRACT FROM AUTHOR]

Arsenate-reducing microorganisms may mobilize arsenic into groundwater. Phylogenetic DNA sequence information cannot exclusively be used to infer arsenate reduction, as the spotted homologies may not translate to biochemical activities. We here develop a cultivation-based metagenomic strategy for inferring actual activities: we complement a cultivation-independent microbial community survey covering 22 arsenic-contaminated drinking water wells in Bangladesh, with the characterization of enrichments of anaerobic arsenate reducers. All investigated samples revealed microbial arsenate reduction activity. The enriched microbial communities were phylogenetically diverse within and between the enrichments. The enrichment also unveiled species: the arsenate-reducing enrichments held 16S rRNA gene sequences closest to Dechloromonas sp., Azonexus fungiphilus, Youngiibacter fragile, Methanogenic prokaryote and Fusibacter sp., in addition to arsenate-reducing Sulfurospirillum strains NP4, b10 and dissimilatory iron-reducing Geobacter species. The enriched arsenate reductase gene (arrA) sequences were closest to sequences in known arsenate reducing Sulfurospirillum barnesii. This study bridges the knowledge gap between cultivation-independent and cultivation-dependent analyses. It clarifies the mechanism for arsenic mobilization and redistribution in rural drinking water wells, as a balance between bioremediation and harmful activities. The identified, potentially dissimilatory arsenate and iron-reducing microbes, constitute a risk for arsenic bioremediation. Appropriate metagenomic and dynamic analyses should help design and maintain safer, effective bioremediation. [ABSTRACT FROM AUTHOR]

Exopolysaccharide (EPS) production represents an adaptive strategy developed by extremophiles to cope with environmental stresses. The EPS-producing Bacillus licheniformis B3-15, of shallow marine vent origin (Vulcano Island, Italy), was previously reported as tolerant to arsenate (AsV). In this study, we evaluated: (i) the increasing production of EPS by Bacillus licheniformis B3-15 in the novel SG17 medium; (ii) the arsenic absorption capacity of the EPS by mass spectroscopy; (iii) the functional groups of EPS interacting with As by ATR-FTIR spectroscopy; and (iv) the ability of EPS to prevent arsenic toxicity by the bioluminescent assay. The EPS yield (240 mg L−1) was 45% higher than previously reported. The EPS was mainly constituted of disaccharide repeating units with a manno-pyranosidic configuration and low protein content, attributed to the poly-gamma glutamic acid component as evidenced by NMR analysis. ATR-FTIR spectra indicated that the functional groups of the EPS (O–H, C=O, C–O and C=C and N–O) were involved in the adsorption of the arsenic cations, with greater interactions between EPS and arsenate (AsV) than arsenite (AsIII). Consequently, the EPS at increasing concentration (100 and 300 µg mL−1) adsorbed AsV more efficiently (20.5% and 34.5%) than AsIII (0.7% and 1.8%). The bioluminescence assay showed that the EPS was not toxic, and its addition reduced the toxicity of both As forms by more than twofold. The crude EPS B3-15 could be used in arsenic bioremediation as a possible eco-friendly alternative to other physical or chemical methods. [ABSTRACT FROM AUTHOR]