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Massive amounts of biogas slurry are produced due to the development of biogas plants. The pollution features and the risk of biogas slurry were fully evaluated in this work. Thirty-one biogas slurry samples were collected from sixteen different cities and five different raw materials biogas plants (e.g. cattle manure, swine manure, straw-manure mixture, kitchen waste and chicken manure). The chemical oxygen demand (COD), ammonia nitrogen ( NH 4 + - N ), anions (e.g. Cl−, SO 4 2 - , NO 3 - and PO 4 3 - ), antibiotics (e.g. sulphonamides, quinolones, β2-receptor agonists, macrolides, tetracyclines and crystal violet) and heavy metals (e.g. Cu, Cd, As, Cr, Hg, Zn and Pb) contents from these biogas slurry samples were systematically investigated. On this basis, risk assessment of biogas slurry was also performed. The concentrations of COD, NH 4 + - N and PO 4 3 - in biogas slurry samples with chicken manure as raw material were significantly higher than those of other raw materials. Therefore, the biogas slurry from chicken manure raw material demonstrated the most serious eutrophication threat. The antibiotic contents in biogas slurry samples from swine manure were the highest among five raw materials, mostly sulphonamides, quinolones and tetracyclines. Biogas slurry revealed particularly serious arsenic contamination and moderate potential ecological risk. The quadratic polynomial stepwise regression model can quantitatively describe the correlation among NH 4 + - N , PO 4 3 - and heavy metals concentration of biogas slurry. This work demonstrated a universal potential threat from biogas slurry that can provide supporting data and theoretical basis for harmless treatment and reuse of biogas slurry.

Environmental pollution and food contamination are as old as the civilization itself. It is the consequence of the development of civilization, over utilization of nature, industrialization and in fact a price for the progress. It is highly prominent in Dhaka city. Air pollution is mainly due to the vehicle emission, industrial discharge and burning of fossil fuel. The water resource of Dhaka becomes a major health threat due to arsenic contamination, inadequate household/industrial/medical waste disposal and industrial effluent management. Food contamination came from the commercialism of business people who are doing this knowingly to maximize profit. Necessary steps are to be taken to protect the environment for our own existence. This paper reveals chemical pollution and contamination issues of Dhaka city, the capital of Bangladesh. Purpose of the study: Brief review of chemical induced pollution and contamination, their consequences and control. Healthcare providers/Policy makers have a major role play to concerned field. Materials and Methods: Comprehensive literature search followed by consulting healthcare professionals about environmental pollution and food contamination. Hospital, clinic and company personnel, newspaper journalists, NGO workers given their valuable suggestions and asked help for necessary books, journal, newsletters. A few western magazine and newspapers also observed to get necessary concern. Projections were based on public life pattern, their food habits, pollution and contamination sources, waste disposal features of urban life as well as industry and hospital waste disposals. Results and Discussions: Pollution and adulteration are the most notorious enemy of mankind. Civilization has its own drawback that even causing destruction of itself. Very few people raised voice on this but crippled by the facts of commercialism. The scope of this article is limited to chemical pollution of air and water, medical or household waste products and food contaminants and adulterants. A few discussions based on real life experience and recent studies or reports from various journals and news articles are summarized here. Findings: Both general people and the old system, are responsible for this unlivable condition of Dhaka city. Population is not the sole for this instance. A sense of poor rules and regulation is always raised everywhere. Negligence is becoming a contagious disease contaminating illiterate to well educated, all kind of people. Research limitations: Many articles and documents found in concerned area of research, but the scope of this research is on its focus point chemical hazards and burdens of Dhaka city. Still the most important aspect is covered, but fact is less amount of recent data found in few areas. Practical Implication: The language of this article is too simple to understand by people with simple literacy. Journalists, doctors, students, nurses, pharmacists, public representatives, policy makers and regulatory authorities have to acquire much from this article. Social Implication: Any article or research is based on the think beneficence for mankind, at least going ahead from the present situation, overwhelming problems and measures. The article should create a direction for the future policy makers of both government and other sectors to review the frustrating situation of chemical pollutions and food contaminants of Dhaka, along with the whole Bangladesh. Again, world business is moving to Asian countries, Bangladesh will be a major business hub within next few decades. This article should remind policy makers that we should not forget mankind, giving places to industrialization and development.

Arsenic (As) contamination in wells is common throughout the northeastern United States. It is well documented that lead-arsenate (PbHAsO4 ) pesticides were widely used on fruit tree orchards from the 1890s to 1950s. This study evaluates the potential for As contamination of groundwater from former orchards in Connecticut, where there were over 47,000 orchards in 1935. A proximity analysis involving 189 orchards and 114 domestic wells was conducted to assess the spatial relationship between historic orchards and As in wells. Field studies were then conducted to characterize As and lead (Pb) distributions in soils and wells near historic orchards. The proximity analysis found that the wells with no detected As were further away from historic orchards and had fewer historic orchards within their vicinity when compared with wells that contained As. The field investigations found that elevated levels of As and Pb were widespread in soils from orchards established by 1951, with some As concentrations exceeding 200 ppm. In some soils, As and Pb were leachable at concentrations exceeding USEPA drinking water standards in synthetic precipitation laboratory tests. It was also found that the wells nearest to the impacted soils tended to contain the highest As concentrations, while the wells located in areas that were forested prior to 1970 contained no As. Overall, this study found that As and Pb from legacy pesticide residues are still abundant in former orchard soils and that a strong spatial relationship exists between As-contaminated wells and historic orchards. Greater consideration should be given to historic orchard soils as a potential contributing nonpoint source of As to the groundwater in Connecticut, where domestic well contamination rates are high.

In this study, the author report detailed results of the variation of arsenic in groundwater along a transect in an area near the Hanoi city centre. The results showed that 64% of collected samples exceeded the WHO guideline value for arsenic concentration in drinking water. The arsenic concentration varied in a wide range, strongly depending on the sediment characteristics of each zone along the transect. Aside from As, groundwater in this area also was contaminated by elevated concentrations of Fe, Mn, and ammonium. The study also pointed out a positive correlation between As and reductive chemical species, namely DOC, NH4+, and CH4 in groundwater. Although there is no clear trend in the correlation between As and Fe, Mn, it can be concluded that the formation of arsenic in groundwater in the study area was due to the reductive dissolution of As-bearing iron minerals under the presence of organic matter.

Arsenic contamination in groundwater is commonly found in alluvial plains of major river basins, in which the Red river delta has also been reported to be contaminated with high levels of arsenic. In this study, groundwater from 50 household wells was collected to study the spatial distribution of arsenic in northwestern Hanoi. The results showed that arsenic concentration in groundwater varied in a wide range of less than 5 to 334 μg/l, of which up 62% of the wells exceeded the WHO guideline value of 10 μg/l for arsenic content in drinking water. Arsenic groundwater in this area is unevenly distributed throughout the area, high arsenic concentrations are found in a narrow band between Red river and Day river. This pattern of arsenic distribution is strongly related to the sediment age, sedimentary processes, and it is also modified by local groundwater flow parts and the occurrence of hydraulic connection between aquifers, which are observed in the study area. Arsenic is released into the groundwater during the reductive dissolution of arsenic-bearing minerals under the presence of organic matter.

The presence of arsenic in groundwater and other drinking water sources presents a notable public health concern. The utilization of iron-oxide nanomaterials as arsenic adsorbents has shown promising results both in laboratory and field conditions. This study focuses on characterizing the performance of nanoparticles prepared by different synthetic methods and with different surface coatings in arsenic removal. Poly (acrylic acid), polyethylene glycol, polyethylenimine were used to stabilize iron-oxide nanoparticles prepared by thermal decomposition to an aqueous solution. The effect that each polymer has on the materials was evaluated in batch and PEG was found to provide the best performance. To implement the nanoparticles in the field, a continuous flow column study was carried out by depositing the nanoparticles in poly(methyl methacrylate) (PMMA) beads. Even when the surface coatings are required to prevent nanoparticles from agglomerating, further efforts to deposit nanoparticles on a supporting material are required.

Many studies have reported high arsenic concentrations in the groundwater and soil of the Jianghan Plain (JHP), an important rice production base in China. However, no comprehensive study on the occurrence and risk of As in groundwater-soil-rice systems in this region has been conducted. In this study, As concentrations in groundwater, soil, rice straw, and rice grain samples were analyzed. Arsenic concentrations were found to range from BDL to 42.88 μg/L (median 0.34 μg/L) in phreatic water, BDL to 41.77 μg/L (median 8.64 μg/L) in soil pore water, 10.20 to 21.90 mg/kg (mean 16.52 mg/kg) in soil, 0.204 to 2.860 mg/kg (mean 0.847 mg/kg) in rice straw, and 0.131 to 0.951 mg/kg (mean 0.449 mg/kg) in rice grain. Arsenic uptake by rice from soils was evaluated according to bioavailable As defined by chemical extraction and diffusive gradients in thin films. The results indicated that owing to the low content of highly mobile As fractions, the less mobile As fraction (mainly bound with amorphous Fe/Al (hydr)oxides) also contributed to bioavailable As, suggesting that amorphous Fe/Al bound As should be considered in analyzing bioavailable As. In terms of the geoaccumulation index and the Chinese paddy soil standard (GB15618-2018) limit (25 mg/kg), As pollution in water and soils in the study area is at a low level and can be considered relatively safe. However, the target hazard quotients and cancer risk assessment indicated that As pollution is at a dangerous level with potential human health risk. According to the bioconcentration factor, the bioavailability of soil is higher in JHP compared with other rice-growing areas owing to the unique hydrogeological conditions and irrigation using groundwater with high As content. Rice planting areas in JHP should be set as far away from large rivers as possible, and groundwater with high As concentrations must be pre-treated prior to irrigation.

The groundwater quality has undergone a change to such an extent that the use of it could be risky and hazardous due to arsenic contamination. The presence of excess arsenic (> 0.01 mg/L) is area-specific, and the sources of contamination are mostly natural and geogenic. Arsenic-free safe drinking water can be supplied in affected areas by applying the appropriate arsenic removal technologies to groundwater or by the conventional surface water treatment process. Arsenic removal from groundwater is commonly accomplished through co-precipitation and adsorption processes. However, the application of the electrocoagulation method for the removal of arsenic has emerged as an efficient and appropriate technology. In the present study, electrocoagulation experiments were performed in batch mode using three different electrode combinations, viz. mild steel (MS)–stainless steel (SS), MS-MS, and MS–aluminum (Al) electrodes (anode–cathode) of locally available materials with arsenic-contaminated natural groundwater. The arsenic removal efficiency is significantly higher than 99% for MS–SS, MS-MS, and about 67% for MS–Al, and the pH, total dissolved solids (TDS), and iron levels in effluent water are within desirable limits. The value of empirical constants and correlation coefficient (R2) have been estimated for the Langmuir and Freundlich adsorption isotherm models. The R2 value of the Langmuir isotherm fits well for MS–SS, and MS-MS, but MS–Al fitted with the Freundlich isotherm. The kinetic study has been described using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The pseudo-first-order rate of expression has been observed for MS-SS and MS-MS, whereas MS-Al has been followed the pseudo-second-order model. Finally, the intraparticle diffusion model confirms the equilibrium stage.

This paper offers a critical analysis of the arsenic-accumulating, transforming bacteria and their potential use and effect in remediating agricultural soil. Given the worldwide presence, sources, types, and pathways of arsenic, accumulating, and transforming bacteria, and the effect of arsenic contamination on plant and agricultural soil were studied. Diverse published studies have emphasized arsenic characteristics and effects on soil. In this study, we emphasized the biochemical process and the bioremediation mechanism of arsenic contamination. The method used to isolate and identify arsenic-resistant bacteria was also described. This paper provided an overview of the information about the contamination of arsenic, the effect of its accumulation in agricultural fields, and which bacteria are used to metabolize arsenic in soil. Various types of microbes, including Exiguobacterium, Aeromonas, Bacillus, Pseudomonas, Escherichia, and Acinetobacter, metabolize the activity of inorganic arsenic to generate their energy. The bacterial ars operon consists of three to five genes that are located in plasmids. These genes are involved in oxidation, reduction, methylation, or demethylation in the arsenic transformation process in bioremediation. For example, in arsenic (V) reduction, two microbial pathways known are the detoxification pathway arsC genes negotiate and the respiratory pathway arsA genes negotiate. Further, this paper demonstrates briefly the sources of arsenic contamination and its effect on plants and soils. It has been found that certain microbes’ genes facilitate the reduction and oxidization in arsenic toxicity and have some bioremediation capacity to reduce and immobilize the arsenic contamination in agricultural soil.

Arsenic-contaminated food including farmed fish is one of the main routes of human exposure. Fish farmed in contaminated environment accumulates arsenic in different tissues with great variability. Thus, it is utmost important to quantify the risk associated with different farmed fish species in arsenic-contaminated aquaculture systems. In the present study, arsenic content was measured in twelve fish species (Labeo rohita, L. catla, Cirrhinus mrigala, Oreochromis niloticus, O. mossambicus, Liza tade, Puntius javanicus, L. calbasu, Glossogobius giuris, Macrobrachium rosenbergii, Ctenopharyngodon idella, and Bellamya bengalensis (gastropod)) collected from arsenic-contaminated aquaculture systems. Among the studied finfishes, C. idella was found to accumulate the lowest amount of arsenic (

To evaluate the pollution level of toxic elements in edible mushrooms from Jilin Province, China, the lead, cadmium, mercury, and arsenic content present in them were monitored and evaluated. A total of 610 edible mushroom samples, including fresh and dried, were collected from nine cities in the Jilin Province. The concentrations of lead, cadmium, mercury, and arsenic ranged from 0.007 to 3.31, 0.006 to 48.52, 0.003 to 0.56, and 0.008 to 57.34 mg/kg, respectively, in dried samples, and 0.007 to 0.06, 0.006 to 0.17, 0.003 to 0.06, and 0.008 to 0.12 mg/kg, respectively, in fresh samples. The concentration of cadmium and arsenic exceeded the standard (Cd ≤ 0.2 mg/kg, Cd of Lentinus edodes ≤ 0.5 mg/kg, and As ≤ 0.5 mg/kg) in some mushroom samples. The bioconcentration levels of lead, cadmium, mercury, and arsenic depended on the edible mushroom species, environment, and the physicochemical properties of lead, cadmium, mercury, and arsenic. The results of the single factor pollution index, a method used to calculate the level of single elements in substances, showed that all edible mushrooms were at the level of unpolluted except Tricholoma matsutake and Pleurotus eryngii. The comprehensive factor (P) for T. matsutake was 1.093. The comprehensive factor pollution index, a method used to calculate the level of combined mixture in substances, was in the unpolluted level, except for T. matsutake. The pollution index results showed that cadmium and arsenic concentrations were lightly polluting in some mushroom samples. The health risk index for arsenic was the highest. Therefore, more attention should be paid to arsenic contamination in T. matsutake and P. eryngii in the Jilin Province, China. PRACTICAL APPLICATION: In this paper, we evaluated the contamination levels and associated safety issues of four toxic elements, lead, cadmium, mercury, and arsenic, in edible mushrooms. The results showed that cadmium and arsenic concentrations were lightly polluting in some mushroom samples.

Herein the present study focuses on arsenic (As) contamination in groundwater, which plagues a vast section of the population of the world. Even the conservative estimates by the World Health Organization (WHO) estimate the number of people plagued by arsenic contaminated drinking water to be around 140-200 million. The Ganga- Brahmaputra fluvial plains in India and Padma-Meghna fluvial plains in Bangladesh are said to be one of the worst groundwater calamities to the humans. The Arsenic levels in drinking water in some of the most populated states in India are disproportionately higher than those defined by WHO guidelines. The paper, thus, delves into the anomaly in permissible limits defined by WHO and regional governments and its consequential effects. It briefly analyses the major sources of Arsenic contamination and its health effects in India. The study also looks closely into the states and districts plagued by the As contamination and explores the prominent treatment methods employed in as removal from the drinking water. Keywords: Arsenic, Adsorption, Geogenic, Arsenopyrite, Oxidation treatment

Arsenic contamination above allowable limit in groundwater is universally been identified as a critical threat with a high alarm in the African countries, Western USA and a lot of different developing countries. The increasing numbers of arsenicosis patients with their extremely grave and fatal fates, imposes severe stringency to the treatment strategies. Though numerous types of technologies were adopted regarding the abatement of arsenic from water but as far the generated sludge from arsenic removing groundwater treatment plant is concerned, scanty efforts were put forward towards wise stabilization/capturing/encapsulation of arsenic sludge to provide zero chances of leaching. Thus, arsenic with the ability of leaching back to soil and water while mixing with surface and under-ground water, still stands as a serious and open challenge to the scientific communities for their safe disposal. With an extensive review towards available technologies for safe arsenic sludge disposal, this paper reviews the potential of stabilization of arsenic recalcitrant sludge employing concrete, polymer compounds, fly ash, adding chemicals and by formation of bricks and cement blocks. Such approaches stand out as flexible and economic strategies while permanently capturing stabilized arsenic in solid matrices while sustaining the strength of the building material. Thus, the requirements of coarse aggregate for the formation of concrete blocks could also be reduced. Such a review is expected to initiate influential policies among the research community to combat against the widespread risk of reluctant disposal practices of lethal arsenic sludge generated from arsenic abating water purification methodologies.

Arsenic in water at low concentration (1–5 mg/L) presents difficulty in its removal by adsorption due to low concentration gradient. In the present study, silica was extracted from rice husk ash vi...

The relevance of groundwater hydrogeochemistry to explain the occurrence and distribution of arsenic in groundwater is of great interest. The insightful discussions on the control of shallow groundwater (

Arsenic in private drinking water wells is a significant problem across much of eastern Wisconsin, USA. The release mechanism and stratigraphic distribution of sulfide and iron (hydr)oxide sources of arsenic in bedrock aquifers are well understood for northeastern Wisconsin. However, recent geologic mapping has identified numerous small bedrock folds to the south, and the impact of these geologic structures on local groundwater flow and well contamination has been little studied. This paper examines the hydrologic and structural effects of the Beaver Dam anticline, southeast Wisconsin, on arsenic in groundwater in the region. Multivariate logistic regression shows wells near the Beaver Dam anticline are statistically more likely to detect arsenic in groundwater compared to wells farther away. Structural and hydrologic changes related to folding are interpreted to be the cause. Core drilled near the fold axis is heavily fractured, and many fractures are filled with sulfides. Elevated hydraulic conductivity estimates are also recorded near the fold axis, which may reflect a higher concentration of vertical fractures. These structural and hydrologic changes may have led to systematic changes in the distribution and concentration of arsenic-bearing mineral hosts, resulting in the observed detection pattern. For areas with similar underlying geology, this approach may improve prediction of arsenic risk down to the local level.

Arsenic in groundwater caused the black-foot disease (BFD) in many countries in the 1950–1960s. It is of great importance to develop a feasible method for removal of arsenic from contaminated groundwater in BFD endemic areas. Photocatalytic oxidation of As(III) to less toxic As(V) is, therefore, of significance for preventing any arsenic-related disease that may occur. By in situ synchrotron X-ray absorption spectroscopy, the formation of As(V) is related to the expense of As(III) disappearance during photocatalysis by TiO2 nanotubes (TNTs). Under UV/Vis light irradiation, the apparent first-order rate constant for the photocatalytic oxidation of As(III) to As(V) is 0.0148 min−1. It seems that As(III) can be oxidized with photo-excited holes while the not-recombined electrons may be scavenged with O2 in the channels of the well defined TNTs (an opening of 7 nm in diameter). In the absence of O2, on the contrary, As(III) can be reduced to As(0), to some extent. Cu(II) (CuO), as an electron acceptor, was impregnated on the TNTs surfaces in order to gain a better understanding of electron transfer during photocatalysis. It appears that As(III) can be oxidized to As(V) while Cu(II) is reduced to Cu(I) and Cu(0). The molecular-scale data are very useful in revealing the oxidation states and interconversions of arsenic during the photocatalytic reactions. This work has implications in that the toxicity of arsenic in contaminated groundwater or wastewater can be effectively decreased via solar-driven photocatalysis, which may facilitate further treatments by coagulation.

The present study aims to carry out the assessment of arsenic contamination in groundwater samples along with the health status of the exposed population of Buxar district of Bihar. In the present study, randomly 80 groundwater samples were collected from the handpumps across the village households. For the health assessment, blood samples from human subjects were collected from the same household to know the status of the arsenic contamination in their body and were analysed. The study showed significantly very high arsenic contamination in their handpumps as well as in the blood samples of the exposed subjects. The maximum arsenic concentration observed in the handpump water sample was 1908 μg/L, while in blood sample of an individual was 462.1 μg/L. Cancer in 12 subjects was also observed within 2 years. The mitigation intervention was carried out by installing an arsenic filter plant for this arsenic exposed village population. After one year of the usage of the installed arsenic filter, there was significant reduction in the disease symptoms in the exposed population. The present study deciphers the groundwater status as well as the health status of the arsenic exposed population of a village of Bihar along with an mitigation approach to overcome the disease burden.

The sources and fate of antimony (Sb) and arsenic (As) in water resources around antimonite (a.k.a. stibnite) deposits is of great concern due to their adverse effects on the environment and human ...

The study was conducted to explore the influence of geomorphic features scattered throughout the area on the occurrence and distribution of arsenic in shallow groundwater. GIS techniques were frequently used to identify the geomorphic features and to correlate with arsenic distribution patterns. The study shows that the occurrence of geomorphic features and their distribution have a vital role in the heterogeneous distribution pattern of arsenic in shallow groundwater. The frequency distribution of geomorphic features is found similar to the arsenic distribution pattern. The moderate to highly contaminated zones are mostly consolidated to the central and southeastern part of the study area. Arsenic contamination levels are varying in different fluvial plains of the study area following the trend of Older Deltaic Plain (ODP) > Older Flood Plain (OFP) > Active Flood Plain (AFP). It has also been observed that arsenic contamination along the different geomorphic features follows the trend of abandoned channels > back swamps > other water bodies > swamps > cut-off meanders > meander scars > ponds > oxbow lakes > channel bar > point bars >channel islands. The present study indicates that the geomorphic features play a significant role in the mobilization of arsenic in shallow groundwater by supplying accumulated organic matter.

Arsenic is a metalloid, which may be found in surface water, ground water, plants and rocks. In high concentrations, its compounds are considered to be genotoxic and carcinogenic. Its levels in drinking water must be regularly monitored and controlled. The objective of study was to determine the concentration of arsenic in water with reference to WHO limits from selected boreholes in Nairobi County, Kenya. Water was randomly sampled from a total of 63 boreholes in five zones (Central, Eastern, Northern, Western and Southern) during dry and wet season. The arsenic was analyzed by Hydride Generation Atomic Absorption Spectrometer (HG-AAS). The results showed that the arsenic content in borehole water during dry season ranged between 0.00455±0.0022 and 0.01007±0.006 and in the range of 0.002057±0.0008 - 0.00744±0.0051 mg/L during the wet season. There was significant difference (P˂0.05) in arsenic content in borehole water samples in Central zone compared to the other zones. During the dry season, arsenic content in water from ten boreholes (16%) and four boreholes (6%) during wet season was found to be above the WHO recommended limit of 0.01 mg/L. The calculated contamination factor for the borehole water ranged from slightly arsenic contaminated in Central zone to very slightly contaminated in the other zones during dry season. During the wet season, the borehole water in all the five zones were very slightly contaminated with arsenic. The pollution index showed that the boreholes in all the five zones during both wet and dry seasons were not polluted with arsenic. Steps should be taken to monitor and treat borehole water for domestic purposes in order to mitigate the effect on human health due to arsenic contamination.

Arsenic (As), a heavy metalloid, occupies the topmost position in the list of the top ten hazardous chemicals published by the World Health Organization. The contamination of arsenic in groundwater predominantly utilized for irrigation and drinking is responsible for serious public health issues across the globe. The two most common arsenic species, i.e., inorganic arsenate and arsenite, are toxic and environmental pollutants. The toxicity of arsenic and its speciation are impacted by bacterial biotransformations. Bacteria have evolved several systems to deal with arsenic toxicity in their vicinity through detoxification and metabolism. The knowledge about these processes provides insight into the strategies employed by bacteria for arsenic biotransformation. In this study, we comprehensively discuss the genetics and molecular mechanisms of arsenate reduction, arsenite oxidation, methylation/demethylation, and other arsenic biotransformations. Relatively recent scientific discoveries and the use of molecular approaches have notably enhanced our understanding of these microbial processes present in the environment. The present review intends to focus on the diverse categories of arsenic-transforming and -metabolizing bacterial species and their genetics, recent advances in the mechanisms of the microbe-mediated As-biotransformation pathways, and their implications on the biogeochemical cycling of arsenic in nature. This review will further help to develop a better understanding of bacterial response to arsenic, bioremediation strategies, and future research fields.

Environmental arsenic exposure in adults and children has been associated with a reduction in the expression of club cell secretory protein (CC16) and an increase in the expression of matrix metalloproteinase-9 (MMP-9), both biomarkers of lung inflammation and negative respiratory outcomes. The objectives of this study were to determine if the levels of serum CC16 and MMP-9 and subsequent respiratory infections in children are associated with the ingestion of arsenic by drinking water. This cross-sectional study included 216 children from three Yaqui villages, Potam, Vicam, and Cocorit, with levels of arsenic in their ground water of 70.01 ± 21.85, 23.3 ± 9.99, and 11.8 ± 4.42 μg/L respectively. Total arsenic in water and urine samples was determined by inductively coupled plasma/optical emission spectrometry. Serum was analyzed for CC16 and MMP-9 using ELISA. The children had an average urinary arsenic of 79.39 μg/L and 46.8 % had levels above of the national concern value of 50 μg/L. Increased arsenic concentrations in drinking water and average daily arsenic intake by water were associated with decreased serum CC16 levels (β = − 0.12, 95% CI − 0.20, − 0.04 and β = − 0.10, 95% CI − 0.18, − 0.03), and increased serum MMP-9 levels (β = 0.35, 95% CI 0.22, 0.48 and β = 0.29, 95% CI 0.18, 0.40) at significant levels (P < 0.05). However, no association was found between levels of these serum biomarkers and urinary arsenic concentrations. In these children, reduced serum CC16 levels were significantly associated with increased risk of respiratory infections (OR = 0.34, 95% CI 0.13, 0.90). In conclusion, altered levels of serum CC16 and MMP-9 in the children may be due to the toxic effects of arsenic exposure through drinking water. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-021-13070-x.

Rice grains typically contain high levels of toxic arsenic but low levels of the essential micronutrient selenium. Anthropogenic arsenic contamination of paddy soils exacerbates arsenic toxicity in rice crops resulting in substantial yield losses. Here, we report the identification of the gain-of-function arsenite tolerant 1 (astol1) mutant of rice that benefits from enhanced sulfur and selenium assimilation, arsenic tolerance, and decreased arsenic accumulation in grains. The astol1 mutation promotes the physical interaction of the chloroplast-localized O-acetylserine (thiol) lyase protein with its interaction partner serine-acetyltransferase in the cysteine synthase complex. Activation of the serine-acetyltransferase in this complex promotes the uptake of sulfate and selenium and enhances the production of cysteine, glutathione, and phytochelatins, resulting in increased tolerance and decreased translocation of arsenic to grains. Our findings uncover the pivotal sensing-function of the cysteine synthase complex in plastids for optimizing stress resilience and grain quality by regulating a fundamental macronutrient assimilation pathway., Contamination of paddy soils can lead to toxic arsenic accumulation in rice grains and low levels of the micronutrient selenium. Here the authors show that a gain of function mutant affecting an O-acetylserine (thiol) lyase enhances sulfur and selenium assimilation while reducing arsenic accumulation in grains.

A novel arsenic adsorbent with hydrous cerium oxides coated on glass fiber cloth (HCO/GFC) was synthesized. The HCO/GFC adsorbents were rolled into a cartridge for arsenic removal test. Due to the large pores between the glass fibers, the arsenic polluted water can flow through easily. The arsenic removal performance was evaluated by testing the equilibrium adsorption isotherm, adsorption kinetics, and packed-bed operation. The pH effects on arsenic removal were conducted. The test results show that HCO/GFC filter has high As(V) and As(III) removal capacity even at low equilibrium concentration. The more toxic As(III) in water can be easily removed within a wide range of solution pH without pre-treatment. Arsenic contaminated ground-water from Yangzong Lake (China) was used in the column test. At typical breakthrough conditions (the empty bed contact time, EBCT = 2 min), arsenic researched breakthrough at over 24,000 bed volumes (World Health Organization (WHO) suggested that the maximum contaminant level (MCL) for arsenic in drinking water is 10 mg/L). The Ce content in the treated water was lower than 5 ppb during the column test, which showed that cerium did not leach from the HCO/GFC material into the treated water. The relationship between dosage of adsorbents and the adsorption kinetic model was also clarified, which suggested that the pseudo second order model could fit the kinetic experimental data better when the adsorbent loading was relatively low, and the pseudo first order model could fit the kinetic experimental data better when the adsorbent loading amount was relatively high.

Presence of arsenic in groundwater, eventually in drinking water, has been recognised as a serious community health problem, due to its high toxic nature. Therefore, its removal is highly essential...

Arsenic (As) is a global public health and environmental problem because of its non-degradable and toxic nature. This study was carried out to assess the As contamination and potential health risk ...

Industrial horticulture can release pesticides and trace metals/metalloids to terrestrial and aquatic environments. To assess long-term and more recent land contamination from an expanding horticultural region, we sampled soils from chemical mixing, crop production, and drainage areas, as well as retention reservoirs (dam) sediments, from 3 blueberry farms with varying land-use history in subtropical Australia. Soils were analysed for 97 different pesticides and trace metal/metalloid contents. The most recent farm had fungicides propiconazole and cyprodinil contents that may compromise soil invertebrate survival and/or nutrient recycling (5–125 mg kg−1). A site previously used to cultivate bananas had 6 dam sediment subsamples with arsenic contents over sediment quality guidelines (SQG); however, the soil content values were just below Australian health investigation levels (100 mg kg−1). Arsenic is suspected to originate from pesticide application during previous banana cultivation in the region. Dam sediment cores at all sites had mercury contents over the SQG likely due to fungicides or fertiliser impurities. Mean contents of mercury from dam sediments (141 ± 15.5 µg kg−1) were greater than terrestrial soils (78 ± 6.5 µg kg−1), and sediment profiles suggest mercury retention in anoxic sediments. Soils in chemical mixing areas at two sites were contaminated with copper and zinc which were above the national soil ecological investigation levels. Based on toxicity data, distribution, persistence, and mobility, we identified the fungicide cyprodinil, mercury, and phosphorus as contaminants of the greatest concern in this intensive horticulture area of Australia. Additional sampling (spatial, chemical speciation, biotic) is required to support mitigation efforts of the emerging contamination in the rapidly expanding blueberry farms of this region of Australia.

Introduction: Environmental arsenic contamination is a major toxicological problem worldwide due to its carcinogenic and nephrotoxic potential. Aim: The purpose of this observational study was to determine the suspected association between urinary arsenic (uAs) and urinary leucine (or leucyl) aminopeptidase 3 (uLAP3) to evaluate uLAP3 as a candidate biomarker of exposure to airborne arsenic. Materials and Methods: A total of 918 adults occupationally and/or environmentally exposed to airborne arsenic were enrolled in the study. Baseline information (age; sex; history of smoking; alcohol, fish and seafood consumption) was gathered. Total uAs concentrations [μg/L] of 918 subjects, as well as the sum of arsenic species (ΣiAs) in 259 subjects, were obtained. Urinary LAP3 was measured by an immune-enzymatic assay using an ELISA kit. Urinary creatinine concentration was assessed with the IB/lAB/1289 research protocol (version II, 2015-09-17). The values of uAs and uLAP3 were recalculated per unit of creatinine. The association between uAs and uLAP3 was assessed using a logistic regression model adjusted for confounders. Results: The study identified a positive correlation between the logarithm of uAs and the logarithm of uLAP3 in the study population (r = 0.1737, p < 0.0000) and between urinary creatinine and uLAP3 concentration not adjusted for creatinine level (r = 0.1871, p < 0.001). In the logistic regression model, there was also an association between increased (≥15 µg/L) uAs and decreased (below the 25th quartile) uLAP3 [OR uLAP3 = 1.22 (95% CI 1.03 to 1.44, p < 0.02)]. Conclusions: These data suggest that urinary LAP3 may be a potential biomarker of arsenic exposure, which warrants further study.

This review explains the transport, mobility, resistance and detoxification of toxic metalloid arsenic (As) in plants. Arsenic is ubiquitously present in Earth’s crust; however, numerous human interventions such as rapid industrialization use of As-based pesticides, insecticides and discharge of industrial wastes in water bodies leads to cumulative increase in As in the environment and has become a global challenge. Arsenic exists in different organic and inorganic forms, but inorganic forms such as pentavalent arsenate (AsV) and trivalent arsenite (AsIII) are more toxic and actively taken up by plants. Its toxicity is marked by generation of reactive oxygen species (ROS) that are capable of degrading various biomolecules of the cellular systems. To keep the ROS under the limit, plants have an array of enzymatic antioxidants such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione-S-transferase (GST); and non-enzymatic antioxidant like ascorbate, proline, and cysteine. Contrary to this, As-hyper-accumulator plants survive under high concentration of As through the strenuous action of Asv reduction into AsIII followed by the vacuolar compartmentalization of complex or inorganic As. Hence, this review focuses on the potential sources of As in the environment, its speciation and toxicity, and tolerance strategies in plants.

Minimization and stabilization of arsenic-containing smelting wastewater and residue is of crucial issue to resolve the arsenic contamination. Calcium arsenate is a typical precipitate produced from disposal of smelting acid wastewater. However, it suffers from poor stability and large quantity in the aqueous environment. Copper slags, as for rich-iron species materials, are disposed of in landfills or open-air tailing ponds, which are another waste material that have not been effectively utilized for reuse application. In this study, strategy for sequence of phase-controlled and thermal-doped copper slag technique was used as the efficient means of minimization and stabilization of arsenic-bearing resides. Detailed results were showed that stepwise phase precipitation significantly reduced the formation of hazardous solid waste; the total solid waste was reduced 47.0 wt% because the gypsum was separated from arsenic calcium residues through two-step methods. Subsequently, solid waste stabilization was achieved by using thermal-doped slag, and the high yield of magnetite (75.6 wt%) and fayalite (22.7 wt%) was produced from copper slags. It was proved that these iron-rich species displayed the remarkable performance to stabilize arsenic due to the formation of Fe-As-Ca-O complex; compared with the raw solid waste, the arsenic leachability was decreased from 280.75 to 1.05 mg/L via copper slag stabilization process. The immobilized arsenic content was 25.0 wt%. Overall, the proposed strategy for stepwise phase-controlled and thermal-doped copper slags was a potentially effective strategy for reducing emissions and pollution of arsenic-containing wastewater and residue.

The study was undertaken for understanding the potential of deep aquifers as a source of safe drinking water and for assessing the status of groundwater aquifer near Madunaghat area, Chattogram. The specific issues are salinity, interconnectivity of the shallow and deep aquifers, mixing of groundwater with the adjacent Halda river water, recharge condition and groundwater age. The isotopic data suggest that most of the groundwater results from a mixture between recent recharge and an older component recharge under climatic conditions cooler than at present. The interconnectivity between shallow aquifers and river waters are mostly found in the line wells installed particularly in shallow depth (16 m) close to Halda river as evidenced from the similar tritium values of sampled line well water with that of the Halda river water. The groundwater in Madunaghat well field area is not affected by salinity, as it is evidenced by higher values of Na/Cl ratio of the groundwater samples compared to the sea water fresh water mixing line. The geochemistry of intermediate and deep groundwater is dominated by Na-Mg-HCO3 and Na-HCO3 type waters. Even the relationship between chloride and oxygen-18 (Cl-δ18O) depicts that the waters from the deep, intermediate and shallow wells do not fall on the seawater mixing line. The Carbon-14 contents of intermediate to deep groundwater samples vary from 16.2 to 59.3 pMC indicating the residence time in the range of 4300 to 15,000 years BP, i.e., the sourced water recharged the aquifers a long time ago. The intermediate and deep wells have water with arsenic concentrations less than the detection limit of 3.0 μg/L. Only a few shallow wells have arsenic concentrations greater than the detection limit varying from 13.7 - 47.4 μg/L, which is less than the DoE permissible limit (50 μg/L) implying that the groundwater at Madunaghat area is not affected by Arsenic contamination.

Arsenic contamination in drinking water is a great concern in different regions of the world as well as in India. Several technologies have been investigated to remove arsenic from water, such as coagulation and co-precipitation, ion exchange, adsorption, and reverse osmosis. In the present research, electrocoagulation with iron electrodes has been assessed as a treatment technology for arsenic removal from groundwater to reach concentrations below 0.01 mg/L (WHO limit) and which is technically effective, affordable for the local area, and easy to operate and maintain. Electrochemically generated iron is converted to hydrated ferric oxide within the contaminated water, which takes up the arsenic from water. A downstream filtration unit (sand or activated alumina) is applied to remove ferric hydroxide flocs produced during the process. The laboratory experiments were conducted in a batch reactor using iron plates as electrodes with monopolar configuration to study the effects of initial pH and electro-charge loading (ECL) on arsenic removal. The optimum operating condition was observed for an electro-charge loading of 25-30 Coulombs/L at pH 7.0 and an initial arsenic concentration of 0.2 mg/L. Two field trials were implemented in West Bengal after suitably designing the electrocoagulation system. Arsenic removal was significant (75-80%) delivering safe water with arsenic below 0.01 mg/L (acceptable limit). Passivation of the electrodes occurred during the operation and calcium-based (including iron) deposition was observed on the cathodes. Passivation is avoidable after running regular polarity reversal of the electrodes.

This study investigated Bacillus subtilis ATCC13952 as an adsorbent for arsenic in groundwater. Batch experiments were used to determine the effect of contact time, adsorbent dose, arsenic (III) concentration, pH, and temperature on the process. The percentage of arsenic (III) removed was high at a contact time of four days, 3.0 mL of Bacillus subtilis ATCC13952, pH 8 and temperature of 35°C. The kinetics of the process showed the Elovich kinetics model as the best fit for the process. This indicates that arsenic removal was by chemisorption. The analysis of the nonlinear equilibrium isotherms and the error functions showed the Langmuir isotherm as best fit for the process. Mechanistic study of the process indicated bulk diffusion to be the rate-determining step. Thermodynamically, the process was favourable, spontaneous and feasible. When the community water samples were treated with the Bacillus subtilis ATCC13952 at the optimum contact time, adsorbent dose, pH and temperature, 99.96% - 99.97% of arsenic was removed across all sampling points within the studied communities. Hence, the results show that Bacillus subtilis ATCC13952 is an efficient adsorbent for arsenic in aqueous systems and the organism appears to hold the key to purging the environment of arsenic contamination.

Water is a precious gift of nature provided to humans to sustain on the surface of the earth. Overexploitation of this fundamental resource in an unsustainable manner has deteriorated its natural state. Today, billions of people around the world do not have drinking water on their premises. A large proportion of this limited resource is contaminated and is not fit for consumption. An elevated level of arsenic in the ground waters is one of the worst anthropogenically produced disasters ever. It is one of the contaminants of water resources, which is both naturally present and anthropogenically produced. It is termed as “the king of poison” due to its high toxicity. It has taken more lives than any other toxicity on the earth. More than one billion people in India are currently affected by arsenic-contaminated water and its manifested diseases, particularly in the Ganga-Brahmaputra-Meghna Plains. It has produced a wide range of difficulties for the inhabitant in the affected areas, including health problems, social problems, and economic problems. There are ample studies available dealing with health burdens arising out of consuming arsenic-contaminated water. Still, there is a shortage of studies concentrating on the socioeconomic issues arising out of it. This paper reviews all the previous works on arsenic contamination and related problems. It emphasizes the socio-economic aspects of the problem and analyzes India's arsenic hotspot regions. The study points out that arsenic has put health burdens on the inhabitant and created many interrelated socio-economic issues that need to be taken into proper consideration for future research.

During the late nineteenth and early twentieth centuries, arsenic was used as an embalming agent in the United States. In 1996, Konefes and McGee brought the potential danger of arsenic poisoning during excavation to the attention of archaeologists. They developed methodology that was later refined by the present authors. This article discusses the history of arsenic as an embalming agent, explores socioeconomic and demographic factors that might suggest the presence of arsenic in certain burials, and presents methods for testing arsenic in archaeological contexts. We also discuss environmental impact mitigation considerations and review examples of arsenic testing in archaeological contexts.

Roxarsone (ROX) is widely used in animal farms, thereby producing organoarsenic-bearing manure/wastewater. ROX cannot be completely degraded and nor can its arsenical metabolites be effectively immobilized during anaerobic digestion, potentially causing arsenic contamination upon discharge to the environment. Herein, we designed and tested a sulfate-mediated bioelectrochemical system (BES) to enhance ROX degradation and in situ immobilization of the released inorganic arsenic. Using our BES (0.5 V voltage and 350 μM sulfate), ROX and its metabolite, 4-hydroxy-3-amino-phenylarsonic acid (HAPA), were completely degraded within 13-22 days. In contrast, the degradation efficiency of ROX and HAPA was

Accumulation of heavy metals (Fe, Cu, Zn, Cd, Pb) and arsenic in water and bottom sediments of the Srepok River in rainy and dry seasons has been assessed. Significant seasonal variations in the concentration of elements in water have been found. The Fe, Cu, Zn, As, and Pb content of sediments did not depend on the season, and the concentration of Cd was higher in the rainy season. At certain periods of time, the concentrations of these elements in river water exceeded those recommended by the national technical regulations of Vietnam: Fe, 2.3–9.5 times; Cu, 1.2–2.8 times; Zn, 1.2–4.5 times; Cd, 1.7–6.8 times; Pb, 1.1–17 times; and As, 1.1–3.7 times. The concentrations of all heavy metals and arsenic in the river water and bottom sediments of industrial zones tended to increase. The results showed, the examined elements can be divided into groups where their concentrations are closely interrelated. These groups are composed of Fe, Cu, Zn, and Pb in the river water, and of Cu, Zn, As, and Pb in sediments. The obtained data prove the necessity of monitoring the levels of heavy metals and arsenic in river water and bottom sediments of industrial zones.

Arsenic contamination in drinking water is recognized as major health hazard worldwide. As reported in literature, more than 19% Indians are consuming lethal levels of arsenic for drinking purposes. In this work, arsenic (III) removal was studied using HFN300 polyethersulfone nanofiltration membrane in spiral wound configuration. Various membrane parameters such as hydraulic permeability (4.87 L m−2 h−1 bar−1), mass transfer coefficient (0.957*10−6 m s−1), reflection coefficient (0.9), and solute permeability (2*10−9 m s−1) were estimated using film theory combined Spiegler-Kedem (FTCSK) model. The higher value of reflection coefficient suggested the impervious nature of nanofiltration (NF) membrane used for arsenic (III) solute rejection. The influence of various operating parameters such as transmembrane pressure, initial feed concentration, and feed flowrate on membrane performance was also examined. It was found that arsenic (III) rejection was dependent on pressure and feed concentration. Result showed that more than 96.4% arsenic (III) rejection was achieved for 50 mg L−1 of feed at optimized conditions. As HFN300 membrane was negatively charged at pH 8 and arsenic (III) was available in neutral solute form, electro-migration was not considered for solute rejection mechanism. Solution diffusion with significant coupling between solute and solvent, steric hindrance effect, convection, and solute-membrane affinity interactions were considered dominant factors for the possible solute rejection mechanism. Rejection efficiency (% R) and permeate flowrate (Q2) were simulated and compared with experimental results. It was found that simulated results were in excellent agreement with the experimental results. The maximum error obtained was within 10% for both % R and Q2. This confirms the efficacy of FTCSK model in predicting arsenic (III) removal using NF membrane. The annualized cost per cubic metre of treated water was estimated as 3.32 $/m3. This further confirms the feasibility of using NF process in removing arsenic from contaminated water.

This study was undertaken to quantify the naturally occurring arsenic in the groundwater and chemical body burden caused by its ingestion at some villages of Fatehabad district, Haryana, India. The arsenic levels in groundwater were quantified by hydride generation atomic absorption spectrometry (HG-AAS). Arsenic concentration in the groundwater was found to be in the range of

Arsenic contamination of water in the Red River and Mekong deltas brings the largest mass poisoning calamity in human history because drinking of arsenic contaminated water can cause cancers of the skin, lungs, bladder and kidney and other harmful diseases. In general, the arsenic exists in difference oxidation states such as –3, 0, +3, and +5, among which As(+3) has been considered as the most dangerous contaminant in the water. Synthesis of nature friendly and low cost, portable, and effective adsorbent for removal of arsenic in contaminated water is very essential for many countries where development of large industrial setup is difficult. In this work, we introduce a facile method for preparation of Iron Oxide (Fe2O3) coated N-doped Titanium Oxide (TiO2) nanoparticles (FNT NPs) towards effective removal of As(III) from drinking water. The FNT NPs were synthesized by a scalable low temperature, solution based hydrothermal method using as Iron(III) chloride (FeCl3), and N‑doped TiO2 NPs as starting materials. The prepared FNT NPs were characterized by Scanning electron microscopy (SEM), Energy-Dispersive X-Ray (EDS), and Transmission electron microscopy (TEM), whereas the As(III) adsorption studied were done using Inductively coupled plasma mass spectrometry (ICP) analysis. Results pointed out that the high quality FNT NPs were successfully synthesized by a low temperature hydrothermal method with uniform size and shape. The adsorption test confirmed that the prepared FNT NPs can effectively remove the As from the water. The results shows 99.34% As(III) form water was adsorbed using the prepared FNT NPs within 60 min. The results shows synthesized FNT NPs, could provide large specific surface area for effective adsorption sites for capturing and removal of As(III) in the water.

An investigation study was conducted in Bukit Merah Reservoir (BMR) for the assessment of arsenic concentration in the surface sediment in 23 sampling stations. The sediment samples were digested and analysed for arsenic using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Sediment parameters such as pH (4.42 ± 0.71), redox potential (121.77 ± 42.45 mV), conductivity (205.7 ± 64.07 μS cm–1) and organic matter (25.35 ± 9.34%) were also examined. The main objectives of this study are to determine the arsenic distribution and concentration and at the same time to assess the enrichment of arsenic using the geoaccumulation index (Igeo) and enrichment factor (EF). This study shows the total arsenic concentration in the surface sediment of BMR is 4.302 ± 2.43 mg kg–1 and found to be below the threshold value of Canadian Interim Sediment Quality Guidelines (ISQG). High arsenic concentration is recorded near the southern part of the lake where anthropogenic activities are prevalent. Based on Igeo, 13% of sampling stations are categorised as moderately polluted, 52.2% as unpolluted to moderately polluted and the rest is categorised as unpolluted. EF shows 78.3% stations are classified as extremely high enrichment and the rest as very high enrichment. This finding provides important information on the status of arsenic contamination in BMR and creating awareness concerning the conservation and management of the reservoir in the future.

The rapid development of Rayong Province has resulted in increased demands on groundwater usage. This has potentially induced the release of contaminants such as arsenic (As), among others (i.e., NO3-, PO43-) from various land use types-especially in intensive agricultural areas and heavy industrial areas, including landfill sites. The objectives of this research are to investigate the As speciation and groundwater chemistry occurring due to different hydrogeological settings and the influence of human activities and to explain the mechanism of As release in the coastal alluvial aquifers in Rayong Province using multivariate statistical techniques and hydrogeochemical modeling (PHREEQC). Six major water facies, mainly consisting of Ca-Na-HCO3-Cl and Ca-Na-Cl, were included in the hydrochemical analysis. Arsenic levels were inversely correlated with NO3-, SO42-, DO, and ORP, confirming the reducing environment in the groundwater system. The results from the PHREEQC model show that most wells were strongly under-supersaturated with respect to arsenorite, scorodite, and arsenic pentoxide. Arsenic (As) is probably derived from the dissolution of Fe oxide and hydroxide (i.e., Fe(OH)3, goethite, maghemite, and magnetite). The multivariate statistical techniques revealed that the As species mainly consisted of As(III), governed by the reducing environment, while As(V) may be desorbed from Fe oxide and hydroxide as the pH increases. Anthropogenic inputs and intensive pumping may enhance the reducing environment, facilitating the release of As(III) into the groundwater. The knowledge gained from this study helps to better understand the mechanisms of As contamination in coastal groundwater aquifers, which is useful for groundwater management, including the optimum pumping rate and long-term monitoring of groundwater quality.

Naturally occurring arsenic is one of the most important groundwater contaminants threatening drinking water quality worldwide, but the extend of the risk is geographically variable. In this resear...

Excavated soils and rocks, containing toxic metals and/or metalloids from geogenic sources, are usually generated in huge volumes at construction sites. And the post-excavation leaching of these toxic metals and/or metalloids with low concentrations, but higher than the environmental standards, is a major environmental concern. A sorption layer method was developed as a cost-effective countermeasure for treating and reusing such excavated soils and rocks. The method utilizes a permeable soil layer, with sorption capacity at the bottom of the embankment, to retain the chemicals of concern that have dissolved in the leachate. Clean host soil, amended with toxic metal-immobilizing agents, is often used as the sorption layer material to strengthen the sorption performance. This study examined the feasibility of applying decomposed granite soil, amended with calcium-magnesium (Ca-Mg) composite powder, as the sorption layer material against the natural contamination of arsenic (As). The hydraulic and sorption performances, along with the effect of the mix proportions and curing periods, were evaluated through batch sorption tests, hydraulic conductivity tests, and up-flow column percolation tests. The results showed that the sorption performance increased by 15 times when using an additive content of 5% Ca-Mg and that hydraulic conductivity was maintained at around 1 × 10−6 m/s. Neither the hydraulic nor the sorption performance was strongly affected by curing periods up to 28 days. The sorption performance increased with the addition of the Ca-Mg agent of up to 5% in the batch sorption tests. The permeable hydraulic property, with an improved sorption capacity due to the soil-agent mixture, indicated that it is a promising material for use with the sorption layer method for treating huge amounts of soils with low levels of contamination.

Iron oxides control the mobility of a host of contaminants in aquifer systems, and the microbial reduction of iron oxides in the subsurface is linked to high levels of arsenic in groundwater that affects greater than 150 million people globally. Paired observations of groundwater and solid-phase aquifer composition are critical to understand spatial and temporal trends in contamination and effectively manage changing water resources, yet field-representative mineralogical data are sparse across redox gradients relevant to arsenic contamination. We characterize iron mineralogy using X-ray absorption spectroscopy across a natural gradient of groundwater arsenic contamination in Vietnam. Hierarchical cluster analysis classifies sediments into meaningful groups delineating weathering and redox changes, diagnostic of depositional history, in this first direct characterization of redox transformations in the field. Notably, these groupings reveal a signature of iron minerals undergoing active reduction before the onset of arsenic contamination in groundwater. Pleistocene sediments undergoing postdepositional reduction may be more extensive than previously recognized due to previous misclassification. By upscaling to similar environments in South and Southeast Asia via multinomial logistic regression modeling, we show that active iron reduction, and therefore susceptibility to future arsenic contamination, is more widely distributed in presumably pristine aquifers than anticipated.

Background: Arsenic contamination in groundwater of Bangladesh was first detected in 1993 and still a major public health problem in the country. In 1997, Samta was identified as a severely arsenic contaminated village and many villagers were found to suffering from arsenicosis. Methods: A series of surveys were carried out in Samta village in the years 1997, 2002, 2008 and 2017 to assess the situation of arsenic contamination and the status of arsenicosis in the village. The water sources and the entire population of the village were included in the study. Results: In 1997 about 87% of the shallow tubewells in Samta village were arsenic-contaminated and 10.1% villagers had arsenicosis. Twenty years later in 2017, about 90% shallow tubewells were arsenic contaminated, 39 deep tubewells and a pond sand filter were installed in the village and 2.3% of the villagers had arsenicosis. On an average 43.8% arsenicosis patients had recovered from the illness and condition of 21.2% patients had deteriorated or remained unchanged. During the 20-year period 37(6.1%) arsenicosis patients and 185(1.6%) non-arsenicosis villagers had died. The main cause of death among arsenicosis patients was cancer (40.5%) and among non-arsenicosis villagers the cause was geriatric problem (11.8%). The mean age at death was 57.6 years and 61.2 years respectively. Conclusion: In twenty years, measures were undertaken to make available arsenic-safe water options and people were motivated to stop the use of arsenic-contaminated water and to increase the intake of protein and vitamin AEC rich food. Recovery had occurred in a substantial proportion of patients.