Levels Of Arsenic In Groundwater Research Articles

Arsenic in the Tibetan Plateau’s geothermal systems: a detailed analysis of forms, sources, and geochemical behaviors

In high-altitude tectonic regions, significant geothermal activity influences groundwater arsenic levels, presenting crucial resource and environmental challenges. The present study examines the Gonghe-Guide Basin located in the northeastern region of the Qinghai-Tibet Plateau. The study employs a comprehensive approach encompassing field sampling, hydrochemical analysis, thermodynamic modeling, and statistical analysis to ascertain the composition and origins of arsenic in geothermal groundwater. The research data indicates that the geothermal groundwater in the area displays weak alkalinity and medium to high mineralization, with the principal hydrochemical types being SO4−Cl·Na and Cl·Na. The concentration of arsenic has a notable inverse relationship with Cl− and a positive correlation with water temperature and DO. According to thermodynamic calculations, the most common kind of arsenic is As5+. The hydrochemical properties of the research area are shaped by rock weathering, evaporative concentration, and ion-exchange adsorption working together. These factors contribute to the favorable circumstances for the formation and migration of arsenic throughout the environment. Notably, the ion-exchange between sodium ions and calcium and magnesium ions significantly impacts the arsenic concentration. This study marks the first discovery of a unique arsenic contamination pattern in geothermal groundwater within the Gonghe-Guide Basin in the northeastern Tibetan Plateau, revealing a positive correlation between arsenic levels, water temperature, and dissolved oxygen content. This provides a new perspective on understanding arsenic pollution in geothermal groundwater in high-altitude regions.

Spatial Distribution of Arsenic in the Aksu River Basin, Xinjiang, China: The Cumulative Frequency Curve and Geostatistical Analysis

The quality of drinking water is crucial for human health and the sustainable development of societies. The Aksu River Basin, a typical inland river system, has areas where groundwater arsenic levels exceed safe drinking water standards (i.e., arsenic concentrations greater than 10 μg/L). Identifying the causes of high arsenic levels in the basin’s groundwater requires further study. Analyzing the hydrogeochemical composition of the Aksu River basin helps us to understand the spatial distribution of groundwater environments and locate areas with dangerously high arsenic levels. In this research, we collected 196 groundwater samples from along the river. Out of these, 38 samples had arsenic levels above 10 μg/L, which represents 19.4% of the total samples collected. By examining the slope changes in the cumulative frequency curves of major ion ratios and employing geostatistics (specifically, the Kriging interpolation), and taking into account the environmental characteristics of the entire basin, we divided the study area into five sub-regions (Zone I through Zone V). The geostatistical analysis showed a significant spatial variability in groundwater arsenic levels, with a clear spatial correlation. Our findings demonstrate that arsenic concentrations in the Aksu River basin’s groundwater vary widely, with Zones II and III—mainly located in the northeastern part of the basin and in Awat County—being hotspots for high-arsenic water. Factors such as a weak reducing environment, intense evaporation, strong cation exchange, and the low-permeability recharge of surface water contribute to the accumulation of arsenic in the basin’s groundwater. The results of this study are vital for assessing the risk of arsenic contamination in groundwater in similar basins and for identifying critical areas for further investigation and research.

Arsenic geochemical species modeling, prediction, and bioavailability in groundwaters of the Oban Massif, southeastern Nigeria

To ascertain the distribution patterns, source identification, chemical speciation, and bioavailability of arsenic in basement aquifers, 64 groundwater samples were analyzed using hydrochemical and geochemical modeling. It was determined that important ion geochemistry, hydrogeochemical facies, and basic hydrogeochemical parameters are interdependent. Arsenic (As) concentrations varied from 0.001 mg/l to 0.03 mg/l, with a mean of 0.007 mg/l. The results of 4.68% of samples were higher than the allowable level of 0.01 mg/l, i.e., groundwater arsenic levels are not dangerous. Significant ion concentrations decreased from dry to rainy seasons suggesting that ionic concentrations generated by silicate weathering in aquifers became diluted. Abundance trends in metal concentration during the dry and rainy seasons were Fe > Mn > Zn > Ni > Cu > As > Pb > Cd and Fe > Zn > Mn > Ni > Pb > Cu > As > Cd, respectively. Of the two hydrochemical facies discovered, the predominant one was the main alkaline-earth-bicarbonate facies [Ca-(Mg)-HCO3] typical of basement terrains, suggesting the fundamental stage of groundwater evolution. Plots of ionic ratios, metal loads, and principal component analyses showed that ionic concentrations are controlled by geology. Geochemical modeling revealed the presence of aqueous arsenic species, which are the less dangerous arsenates at unsaturated levels and do not currently pose a concern.

Arsenic level in groundwater and biological samples in Khanewal, Pakistan.

Groundwater is the most valuable natural source in our earth's planet, being contaminated in various regions worldwide. Despite considerable research, there are scarce data regarding arsenic (As) levels in groundwater and its build-up in biological samples in Pakistan. The current investigation analyzed As contamination in four tehsils of District Khanewal (Kabirwala tehsil, Jahaniyan tehsil, Mian Channu tehsil, and Khanewal tehsil). For that, 123 groundwater samples, 19 animal milk samples, 20 human nails, and 20 human hair samples were collected from the study area. Arsenic concentration in groundwater was up to 51.8µg/L with an average value of 7.2µg/L. About 28 water samples (23%) had As contents > WHO limit and 38 samples (31%) > DEP-NJ limit. Low levels of As were detected in biological samples. Average As levels were 23µg/L in the milk samples and 298µg/kg in human hair. Arsenic contents were not detected in nail samples, except in one sample from Kabirwala tehsil. The maximum values of hazard quotient and cancer risk in District Khanewal were 4.9 and 0.0022, respectively. It is anticipated that long-term use of As-containing water may led to poisoning of humans in the study area, especially in Kabirwala. Therefore, it is necessary to monitor As contamination in the groundwater of Kabirwala tehsil to reduce the potential health hazards.

A Comprehensive Review of the Latest Advancements in Controlling Arsenic Contaminants in Groundwater

Water contaminated with arsenic is a worldwide problem. This review presents the arsenic contamination in groundwater, its sources, and possible health risk to humans. Groundwater pollution is the most common route of inorganic arsenic exposure in humans. Arsenic concentrations in different countries were analyzed and projected on a map. Because arsenic is widely spread throughout the Earth’s crust, it is present in trace amounts in practically all waterways. Harmful levels of this toxin have been identified in drinking water in some regions. For drinking purposes, the majority of people use groundwater; excess arsenic levels in groundwater have been linked to a variety of negative health impacts on people. Arsenic exposure is the world’s leading environmental cause of cancer. The main aim of this review is to summarize the effective technologies to remove arsenic from drinking water, such as ion exchange, coagulation/flocculation, and membrane technologies like ultra-filtration and electrodialysis, helping to deal with the adverse effects caused by arsenic exposure. All these technologies present different advantages and disadvantages. Electrocoagulation, adsorption, and phytoremediation are the most efficient and cost-effective technologies. The removal efficiencies of arsenic using these technologies and prospects were also included.

Spatial pattern of groundwater arsenic contamination in Patna, Saran, and Vaishali districts of Gangetic plains of Bihar, India.

Groundwater is an essential source of drinking as well as irrigation water. It has recently become a significant challenge to maintain good and safe drinking water for all living beings. The continuous supply of arsenic detected in groundwater poses a severe health problem and has adverse effects on humans and the ecosystem. Researchers also identified arsenic contamination globally across various regions. However, a few studies also identified that the groundwater of Patna, Saran, and Vaishali districts of Bihar is intoxicated by arsenic. To assess the toxic level of arsenic in groundwater, samples from various GPS-based pointed locations were collected from the study area using a GARMIN GPS device. The total concentration of arsenic in drinking water (mostly traces of arsenic, level of μg L-1 or less) can be detected only by sophisticated analytical techniques such as ICP-MS, GF-AAS, and HG-AAS. The standard procedures were followed to determine quality attributes in groundwater. Arsenic contamination persists in most areas and exceeds the permissible limits prescribed by the World Health Organization (WHO), negatively impacting the health of more than 10 million people in the state. The 90.47% and 85.71% groundwater samples of the study area exceeded the permissible limit of the WHO (0.01mg L-1) and Bureau of Indian Standards (BIS (0.05mg L-1), respectively. The analyzed data was obtained, and variability was noticed in total arsenic concentrations ranging from 0.002 to 7.801mg L-1, with a mean value of 0.87mg L-1. Similarly, the water quality attribute like total dissolved solids were identified in 14.28% of samples, which crossed 201 to 1026mg L-1, with a mean value of 375.33mg L-1.

Chronic Exposure to Drinking Water Arsenic and Gallbladder Cancer Risk: Preliminary Evidence from Endemic Regions of India.

Evidence linking arsenic in drinking water to digestive tract cancers is limited. We evaluated the association between arsenic levels in groundwater and gallbladder cancer risk in a case-control study (2019-2021) of long-term residents (≥10years) in two arsenic-impacted and high gallbladder cancer risk states of India-Assam and Bihar. We recruited men and women aged 30 to 69 years from hospitals (73.4% women), with newly diagnosed, biopsy-confirmed gallbladder cancer (N = 214) and unrelated controls frequency-matched for 5-year age, sex, and state (N = 166). Long-term residential history, lifestyle factors, family history, socio-demographics, and physical measurements were collected. Average-weighted arsenic concentration (AwAC) was extrapolated from district-level groundwater monitoring data (2017-2018) and residential history. We evaluated gallbladder cancer risk for tertiles of AwAC (μg/L) in multivariable logistic regression models adjusted for important confounders [Range: 0-448.39; median (interquartile range), T1-0.45 (0.0-1.19); T2-3.75 (2.83-7.38); T3-17.6 (12.34-20.54)]. We observed a dose-response increase in gallbladder cancer risk based on AwAC tertiles [OR = 2.00 (95% confidence interval, 1.05-3.79) and 2.43 (1.30-4.54); Ptrend = 0.007]. Participants in the highest AwAC tertile consumed more tubewell water (67.7% vs. 27.9%) and reported more sediments (37.9% vs. 18.7%) with unsatisfactory color, odor, and taste (49.2% vs. 25.0%) than those in the lowest tertile. These findings suggest chronic arsenic exposure in drinking water at low-moderate levels may be a potential risk factor for gallbladder cancer. Risk factors for gallbladder cancer, a lethal digestive tract cancer, are not fully understood. Data from arsenic-endemic regions of India, with a high incidence of gallbladder cancer, may offer unique insights. Tackling 'arsenic pollution' may help reduce the burden of several health outcomes.

Applying an artificial intelligence model using multidimensional spatial-temporal data to predict arsenic contamination of groundwater

Special attention has been paid in recent years to the social and environmental implications of municipal solid waste. There are potential social and environmental issues associated with storing any waste in landfill. Soil, groundwater, and surface water contamination are issues related to landfill and the migration of contaminants by leaching to adjacent areas. The current research attempts to simulate the penetration of landfill contaminants through groundwater leaching, using PART modeling approaches. Multiple social factors, taken from five years of data from 20 counties and cities in Taiwan were used as predictors of groundwater arsenic content. The results indicate that the proposed model attains a precision rate of 87%. The findings suggest that county and city demographics and the volume of waste removed are two major factors in determining the arsenic content of groundwater. The proposed predictive model can be adopted by agencies as an effective early warning tool for groundwater arsenic levels.

De Novo Design of the ArsR Regulated Pars Promoter Enables a Highly Sensitive Whole-Cell Biosensor for Arsenic Contamination.

Whole-cell biosensors for arsenic contamination are typically designed based on natural bacterial sensing systems, which are often limited by their poor performance for precisely tuning the genetic response to environmental stimuli. Promoter design remains one of the most important approaches to address such issues. Here, we use the arsenic-responsive ArsR-Pars regulation system from Escherichia coli MG1655 as the sensing element and coupled gfp or lacZ as the reporter gene to construct the genetic circuit for characterizing the refactored promoters. We first analyzed the ArsR binding site and a library of RNA polymerase binding sites to mine potential promoter sequences. A set of tightly regulated Pars promoters by ArsR was designed by placing the ArsR binding sites into the promoter’s core region, and a novel promoter with maximal repression efficiency and optimal fold change was obtained. The fluorescence sensor PlacV-ParsOC2 constructed with the optimized ParsOC2 promoter showed a fold change of up to 63.80-fold (with green fluorescence visible to the naked eye) at 9.38 ppb arsenic, and the limit of detection was as low as 0.24 ppb. Further, the optimized colorimetric sensor PlacV-ParsOC2-lacZ with a linear response between 0 and 5 ppb was used to perform colorimetric reactions in 24-well plates combined with a smartphone application for the quantification of the arsenic level in groundwater. This study offers a new approach to improve the performance of bacterial sensing promoters and will facilitate the on-site application of arsenic whole-cell biosensors.

Oxidative Dissolution of Arsenic-Bearing Sulfide Minerals in Groundwater: Impact of Hydrochemical and Hydrodynamic Conditions on Arsenic Release and Surface Evolution.

The dissolution of sulfide minerals can lead to hazardous arsenic levels in groundwater. This study investigates the oxidative dissolution of natural As-bearing sulfide minerals and the related release of arsenic under flow-through conditions. Column experiments were performed using reactive As-bearing sulfide minerals (arsenopyrite and löllingite) embedded in a sandy matrix and injecting oxic solutions into the initially anoxic porous media to trigger the mineral dissolution. Noninvasive oxygen measurements, analyses of ionic species at the outlet, and scanning electron microscopy allowed tracking the propagation of the oxidative dissolution fronts, the mineral dissolution progress, and the change in mineral surface composition. Process-based reactive transport simulations were performed to quantitatively interpret the geochemical processes. The experimental and modeling outcomes show that pore-water acidity exerts a key control on the dissolution of sulfide minerals and arsenic release since it determines the precipitation of secondary mineral phases causing the sequestration of arsenic and the passivation of the reactive mineral surfaces. The impact of surface passivation strongly depends on the flow velocity and on the spatial distribution of the reactive minerals. These results highlight the fundamental interplay of reactive mineral distribution and hydrochemical and hydrodynamic conditions on the mobilization of arsenic from sulfide minerals in flow-through systems.

Is living in a region with high groundwater arsenic contamination associated with adverse reproductive health outcomes? An analysis using nationally representative data from India.

Exposure to groundwater arsenic via drinking water is common in certain geographies, such as parts of India, and causes a range of negative health effects, potentially including adverse reproductive health outcomes. We conducted an ecological analysis of self-reported rates of stillbirth, recurrent pregnancy loss, and infertility in relation to groundwater arsenic levels in India. We used a gridded, modeled dataset of the probability of groundwater arsenic exceeding 10μg/L (World Health Organization drinking water limit) to calculate mean probabilities at the district level (n=599 districts). A spatial integration approach was used to merge these estimates with the third India District-Level Health Survey (DLHS-3) conducted in 2007-08 (n=643,944 women of reproductive age). Maps of district level arsenic levels and rates of each of the three outcomes were created to visualize the patterns across India. To adjust for significant spatial autocorrelation, spatial error models were fit. District-level analysis showed that the average level of stillbirth was 4.3%, recurrent pregnancy loss was 3.3%, and infertility was 8.1%. The average district-level probability of groundwater arsenic levels exceeding 10μg/L was 42%. After adjustment for sociodemographic factors, and accounting for spatial dependence, at the district level, for each percentage point increase in predicted arsenic levels exceeding 10μg/L increased, the rates of stillbirths was 4.5% higher (95% confidence interval (CI) 2.4-6.6, p<0.0001), the rates of RPL are 4.2% higher (95% CI 2.5-5.9, p<0.0001), and the rates of infertility are 4.4% higher (95% CI 1.2-7.7, p=<0.0001).). While arsenic exposure has been implicated with a range of adverse health outcomes, this is one of the first population-level studies to document an association between arsenic and three adverse reproductive pregnancy outcomes. The high levels of spatial correlation suggest that further and targeted efforts to mitigate arsenic in groundwater are needed.

Assessment of Arsenic in Groundwater of Southwestern Haryana, India and Chemical Body Burden Caused by its Ingestion

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 <0.05 to 4.53 µg L−1 which is within WHO and BIS acceptable limits (10 µg L−1). The significant positive correlation between pH - As (r=0.38**; P<0.01) showed that arsenic is more soluble in water at higher pH values. Oral arsenic exposure via groundwater ingestion ranged from <0.003 to 0.31 µg kg−1 day−1 which is significantly lower than WHO and BIS acceptable level (0.68 µg kg−1 day−1). The calculated non-cancer health risk was <1.0 which indicated that chemical burden caused by arsenic through drinking water in the study area is not a cause of concern. The calculated carcinogenic health risk was in the range of <5.06E-06 - 4.59E-04 which is slightly higher than acceptable limits.

Aquifer-Scale Observations of Iron Redox Transformations in Arsenic-Impacted Environments to Predict Future 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.

Arsenic levels in groundwater and its correlation with relevant inorganic parameters in Uruguay: A medical geology perspective

The aim of this work was to perform a groundwater quality monitoring in Uruguay, from the Medical Geology perspective, focusing attention on arsenic levels and its correlations with other relevant inorganic parameters. For this purpose, a total of 46 groundwater samples from private wells, out of the scope of the state-run water utility company, were analyzed. The accuracy of the analytical methods was ensured by using certified reference materials. Arsenic concentration range was 1.72–120.5 μg L−1, half of the samples being above the limit of 10 μg L−1 recommended by WHO for drinking water, with the corresponding risks for human health. Pearson correlations were performed, resulting in strong positive correlations for the pairs As/Cl−, As/F−, As/Na and As/V. These relationships between arsenic and other inorganic parameters in groundwater should be deeply studied, to prevent long-term health effects.

Characterisation of hyper tolerant Bacillus firmus L-148 for arsenic oxidation

Groundwater arsenic pollution causes millions of deaths worldwide. Long term natural and anthropogenic activities have increased arsenic levels in groundwater causing higher threats of arsenic exposure. Arsenic hyper-tolerant Firmicute Bacillus firmus L-148 was isolated from arsenic limiting Lonar lake soil, which tolerated more than 3 M arsenic and could oxidize 75 mM arsenite [As(III)] in 14 days. It oxidized As(III) in presence of heavy metals and had unusual pH optima at 9.2. B. firmus L-148 was studied at the biochemical, protein, genomic and transcript level for understanding its arsenic oxidizing machinery. The proteomic and transcript analysis exhibited the presence of ars and aio operon and supported the inducible nature of ars operon. Robust, hyper-tolerant, fast As(III) oxidizing, least nutrient requiring and multi-metal resistance qualities of the strain were used in microcosm studies for bioremediation. Artificial groundwater mimicking microcosm with 75 mM As(III) was developed. Modulation of carbon source, iron and multi metals affected growth and As(III) oxidation rate. The As(III) oxidation was recorded to be 77% in 15 days in presence of sodium acetate and Fe ions. This microcosm study can be explored for bioremediation of arsenic contaminated water and followed by precipitation using other methods.

Groundwater is important for the geochemical cycling of phosphorus in rapidly urbanized areas: a case study in the Pearl River Delta

The fate of phosphorus in groundwater needs to be understood because phosphorus-rich groundwater is discharged into surface water bodies, which causes eutrophication, especially in urbanized areas. The present study investigated the spatial distributions and driving forces related to the groundwater phosphate levels in various aquifers in the Pearl River Delta (PRD), which has undergone three decades of urbanization, as well as the relationship between groundwater phosphate and arsenic was also discussed. The results showed that most of the high-phosphate (>1.53 mg/L) groundwater occurred in granular aquifers. The proportion of high-phosphate groundwater in granular aquifers was more than four times that in fissured aquifers, whereas high-phosphate groundwater was not observed in karst aquifers in the PRD. High-phosphate groundwater primarily occurred in urbanized areas in the PRD, and the proportion of high-phosphate groundwater had a significant positive correlation with the urbanization level. In granular aquifers, reductive environment and alkalization led to enrichment of the groundwater with phosphate. Anthropogenic sources such as wastewater from township-village enterprises (TVE) and animal wastes were the main sources of high-phosphate groundwater in urbanized areas, and the external input of phosphate enriched the groundwater arsenic levels in urbanized areas. By contrast, geogenic sources such as the release of phosphate from the reduction of Fe/Mn (hydr)oxides and the seawater intrusion accompanied by the release of phosphate from secondary minerals were mainly responsible for the occurrence of high-phosphate groundwater in peri-urban and non-urbanized areas, respectively. The high concentrations of both phosphate and arsenic in groundwater in fissured aquifers were mainly attributed to the infiltration of wastewater from TVEs. In contrast to the granular aquifers, the groundwater Eh and pH conditions were not conductive to the occurrence of high-phosphate groundwater in fissured aquifers.

Hydrogeochemical controls on arsenic mobility in an arid inland basin, Southeast of Iran: The role of alkaline conditions and salt water intrusion

Elevated inorganic arsenic concentrations in groundwater has become a major public and environmental health concern in different parts of the world. Currently, As-contaminated groundwater issue in many countries and regions is a major topic for publications at global level. However, there are many regions worldwide where the problem has still not been resolved or fully understood due to inadequate hydrogeochemical investigations. Hence, this study evaluates for the first time the hydrogeochemical behavior of the arid and previously unexplored inland basin of Sirjan Plain, south east (SE) Iran, in order to assess the controlling factors which influence arsenic (As) mobility and its distribution through groundwater resources. Total inorganic arsenic concentration was measured using inductive-coupled plasma optical emission spectrometry (ICP-OES). Arsenic content in groundwater of this region ranged between 2.4 and 545.8 μg/L (mean value: 86.6 μg/L) and 50% of the samples exceeded the World Health Organization (WHO) guideline value of 10 μg/L in drinking water. Groundwater was mainly of Na-Cl type and alkaline due to silicate weathering, ion exchange and evaporation in arid conditions. Elevated As concentrations were generally observed under weakly alkaline to alkaline conditions (pH > 7.4). Multivariate statistical analysis including cluster analysis and bi-plot grouped As with pH and HCO3 and demonstrated that the secondary minerals including oxyhydroxides of Fe are the main source of As in groundwater in this region. The desorption of As from these mineral phases occurs under alkaline conditions in oxidizing arid environments thereby leading to high levels of As in groundwater. Moreover, evaporation, ion exchange and saltwater intrusion were the secondary processes accelerating As release and its mobility in groundwater. Based on the results of this study, desorption of As from metal oxy-hydroxides surfaces under alkaline conditions, evaporation and intrusion of As-rich saline water are considered to be the major factors causing As enrichment in arid inland basins such as those in southeast Iran. This study proposes the regular monitoring and proper groundwater management practices to mitigate high levels of arsenic in groundwater and related drinking water wells of Sirjan Plain.

Comparative Quantification Study of Arsenic in the Groundwater and Biological Samples of Simri Village of Buxar District, Bihar, India.

Background:In the entire world, about 200 million populations are exposed to arsenic poisoning in groundwater. In Bihar, India about 50 million people are drinking arsenic contaminated water. This has caused various health related problems in the population like skin diseases, anemia, bronchitis, gastrointestinal problems, hormonal imbalance and cancer.Materials and Methods:In the present study, a total of 323 water samples were analyzed for the arsenic levels from the entire Simri village of Buxar district of Bihar and a total of 170 blood samples from the same household's subjects were collected for blood arsenic estimation through Graphite Furnace Atomic Absorption Spectrophotometer (Pinnacle 900T, Perkin Elmer, Singapore). Apart from this the correlation coefficient study between blood arsenic levels, age of the subjects, groundwater arsenic levels and depth of the handpumps were carried out.Statistical Analysis:Data were analyzed with statistical software (GraphPad Prism 5) and while scattered graphs were plotted through statistical software SPSS- 16.0.Results and Conclusion:The maximum arsenic concentration in the groundwater sample found during the study was 1929μg/L and in blood sample was 664.7μg/L. The study denotes high arsenic concentration in the drinking water of the village Simri with the highest concentration ever reported in this part of India. Furthermore, the blood samples have also been observed with high arsenic concentration in the village population which is also the highest reporting ever done in this area. The ill health of the village population also correlates our study.

Influx and efflux of arsenic in cotton fields irrigated with arsenic-contaminated groundwater

Samples of rhizosphere soil, groundwater used for drip irrigation, and mature cotton plants were collected from farms at Kuitun, Xinjiang and analyzed for their arsenic (As) levels to account for the influx and efflux of arsenic in the field. The pH value and the soil-grain-size distribution were found to correlate with the different levels of arsenic accumulated by cotton plants and arable soil layers. The principal component analysis (PCA) indicates that the arsenic level in soil is influenced by the silt content and the arsenic level in groundwater, while the arsenic level in plant roots is affected mainly by the silt content and the arsenic level in soil. As estimated, about 64.6 ± 2.7 μg of arsenic was extracted from soil by one cotton plant, and more than 44% of it was stored in husks. About 0.8-2.6 mg As/(m2 yr) was extracted by plants from soil according to the average dry weight of the plant and the field planting density, while 2.4–28.0 mg As/(m2 yr) entered the soil based on the irrigated groundwater volume and the arsenic level in groundwater. Taking account of the cotton residues left after harvest, up to 85.8% of arsenic in the plants returned to the soil. After calculation, about 0.7–2.2 mg As/(m2 yr) returned to the soil, and thus the actual net arsenic input to the soil could reach 2.3–27.6 mg As/(m2 yr). Because of an obvious rise of the soil arsenic level in Kuitun, Xinjiang, and certain preventive measures should be taken to prevent the propagation of arsenic in the agricultural field.

Arsenic accumulation in paddy plants at different phases of pre-monsoon cultivation

Geogenic arsenic (As) contamination in Bengal Delta Plain is a growing environmental and research concern. Cultivation of staple crops like paddy on these contaminated fields is one of the major routes for human dietary exposure. The present study investigates changes of arsenic concentrations in paddy plant parts, root soil and surface soil throughout the various phases of pre-monsoon (boro) cultivation. Arsenic uptake property of paddy plants collected from 10 fields was found to be dependent on the variety of paddy plant (like Minikit, Jaya) rather than arsenic levels in groundwater (0.074–0.301 mg/l) or soil (25.3–60 mg/kg). Arsenic is translocated from root to aerial parts in descending order. Leaf, stem, root, root soil and surface soil showed a similar trend in their change of arsenic concentration throughout the cultivation period. Arsenic concentration was highest in vegetative phase; sharply declined in reproductive phase; followed by moderate increase in ripening phase. The young root tissues in vegetative (primary) phase could uptake arsenic at a much faster rate than the older tissues in later phases. With the growth of the plant, higher concentrations of iron in root soil in the reproductive phase confirmed the formation of iron plaques on the surface of the root, which sequester arsenic and prevented its uptake by plants. Finally, co-precipitation of arsenic with iron released from crystallized iron plaques results in loosening of the iron plaques from root surface. Thus, soil arsenic concentration increases in the final phase of cultivation which in turn contributes to increased concentration in plant parts.