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Arsenic in groundwater in seven districts of West Bengal, India - The biggest arsenic calamity in the world
Abstract
Arsenic has been found in groundwater in seven districts of West Bengal covering an area 37,493 km2 having about 34 million population. Our survey indicates that 560 villages are arsenic-affected and more than a million people are drinking arsenic contaminated water and more than 200,000 people are suffering from arsenic-related diseases. About 20,000 tubewell waters were analysed for arsenic. Around 45% of these tubewells have arsenic content above 0.05 mg/l. The average concentration of arsenic in contaminated water is about 0.20 mg/l; the maximum concentration of arsenic is found to be 3.7 mg/l. Most of the tubewells water contain arsenic in the form of arsenite arsenate. People having arsenical skin manifestations and drinking contaminated water have high arsenic in hair, nail, urine skin scales. Flow injection-hydride generation-atomic absorption spectrometry has been used for arsenic analysis in various samples. Many people have arsenical skin lesions as: melanosis, leucomelanosis, keratosis, hyperkeratosis, dorsum, non-petting oedema, gangrene, skin cancer. More informations are coming where the arsenic patients are suffering from cancers of bladder, lung, etc. The source of arsenic is geological. The reason why arsenic is leached out from the source is not yet clear but owing to heavy groundwater withdrawal the geochemical reaction in underground may be the reason. The vast surface rain water resource, which West Bengal has should be used properly to combat the situation. Proper watershed management is required urgently.
... Another study suggests that at the lower part of the Holocene aquifer, enrichment of organic matter, and biotite along with the chemical dissolution of these substances have a contribution to the arsenic release mechanism (Seddique et al., 2008). The hypothesis that due to lowering of water level, oxygen enters into the aquifer and executes oxidation of arsenic bearing pyrite thus release of arsenic to groundwater occurs (Das , 1995;Das et al., 1996) is discordant as if this has occurred then arsenic would not be present in groundwater and be adsorbed to FeOOH which is the product of oxidation (Thornton , 1996). According to many authors, long-term geochemical changes and due to oxidation of arsenopyrites (core compound of arsenic), arsenic released in aquifers (Mandal et al., 1996). ...
... The hypothesis that due to lowering of water level, oxygen enters into the aquifer and executes oxidation of arsenic bearing pyrite thus release of arsenic to groundwater occurs (Das , 1995;Das et al., 1996) is discordant as if this has occurred then arsenic would not be present in groundwater and be adsorbed to FeOOH which is the product of oxidation (Thornton , 1996). According to many authors, long-term geochemical changes and due to oxidation of arsenopyrites (core compound of arsenic), arsenic released in aquifers (Mandal et al., 1996). Though some authors contradict this by stating that arsenopyrite does not directly mobilize arsenic (Halim et al., 2009). ...
... found having arsenical skin diseases in 27 districts of Bangladesh with an arsenic level in drinking water above 0.30 mg/l (Chouwdhury et al., 2000). Disease like diffuse melanosis spotted melanosis, leucomelanosis, mucus membrane melanosis, diffuse keratosis, spotted keratosis, hyperkeratosis, gangrene, squamous cell carcinoma, skin, kidney, lung, liver, and bladder cancer were identified in Bangladesh and West Bengal by several epidemiological studies Mandal et al., 1996Dhar et al., 1997;Mazumder et al., 1998). A study in Bangladesh shows that exposure to arsenic concentration may affect the mental health of individuals (Li et al., 2013) (e.g., depression). ...
Large-scale mass poisoning through arsenic contaminated groundwater is a global concern and Bangladesh is among the countries exposed to high concentrations of arsenic in groundwater. As arsenic is a widespread contaminant, several studies have been conducted on it but only a few of these studies were held on micro regions by assessing its role on water quality index. In this study, the source and mobilization of arsenic, its effect on soil and plant, level and consequence of toxicity in human health along with current and potential methods to eliminate arsenic from groundwater in Bangladesh were reviewed based on previous researches. Along with the review, an experimental study was also carried out in an arsenic prone region of Bangladesh named Faridpur Sadar Upazila to delineate the role of arsenic in contamination by generating two synthetic scenarios where water quality was measured by the weighted arithmetic water quality index (WQI) method. From the review it was found that, both geogenic, as well as anthropogenic sources, contribute to arsenic affluence in groundwater in Bangladesh. The most accepted theory states that the Himalayan is the primary geogenic source of arsenic in the Bangladesh. Arsenic arrived in the aquifer transported with sediments which eventually releases into groundwater by several biogeochemical processes. This arsenic-contaminated groundwater is extensively used for drinking purpose and irrigation resulting in accumulation of arsenic in human body, soils and plants. Moreover, the accumulated arsenic in soil and plants transmits into the human body jeopardizes human health. Though, several arsenic removal technologies are now in practice in Bangladesh, more eco-friendly and convenient methods may be utilized to attenuate the level of toxicity. The experimental study revealed that, if the arsenic amount was reduced from the present condition, the overall WQI increases considerably. At one location, the index changed from category E to category B while considering a synthetic scenario of no arsenic in water. This indicates that arsenic is the key pollutant of groundwater in the area. This paper expects the kind attention of the local people and policymakers about the severity of arsenic pollution in the region.
... More than 200 000 (20%) were estimated as having arsenical skin lesions. The population at risk inhabited an area covered by 560 villages with an average arsenic concentration of 0.20 mg l ±1 and a maximum concentration of 3.7 mg l ±1 (Chattarjee et al. 1995, SOES 1995, Mandal et al. 1996. The arsenic contamination in groundwater and its toxic effect on human health in West Bengal is relevant to the situation of Bangladesh. ...
... The alluvial formation in Bangladesh has close geological similarity to that encountered in West Bengal. In Bangladesh the groundwater has also been drawn vigorously through deep tubewells for irrigation purposes particula rly during drought (Chattarje e et al. 1995, SOES 1995, Mandal et al. 1996. ...
The study was carried out in a village in Jessore district, Bangladesh, to identify the epidemiological characteristics of arsenicosis. Eighty-seven per cent of the tubewells had arsenic concentration more than the WHO maximum permissible limit of 0.05 mg l ±1. The mean arsenic concentration was 0.240 mg l ±1 and the maximum concentration was 1.371 mg l ±1. Of the total 3606 villagers, 10% (363) were found to be suffering from arsenicosis. Most of the arsenicosis patients were between 10 to 39 years of age. There were more male patients (52.6%). There were no patients among villagers who consumed tubewell water having arsenic levels less than 0.082 mg l ±1. The majority (93.4%) of the patients were in the first and second stage of arsenicosis. With increasing exposure to arsenic, a simultaneous increase in the severity of clinical manifestations of arsenicosis was observed (F = 43.699; p = 0.000). The time-weighted arsenic exposure varied from 0.248 to 5.482 mg day ±1 and the mean was 1.918 mg day ±1. Melanosis was present in almost all the patient (99.5%) and keratosis was present in 68.9%. Cancer (basal cell epithelioma) was present in three (0.8%) patients. The duration of clinical manifestations of arsenicosis varied from 1 to 12 years and the majority were suffering for 4 ±6 years.
... Results also revealed that in the pre-monsoon season, water samples are oxic in nature compared to the post-monsoon session, and the level of arsenic load is 33% higher in the pre-monsoon than the post-monsoon. However, previous reports did not highlight such strong coherency between ORP and groundwater arsenic level (Kulkarni et al. 2018;Majumdar et al. 2016;Mandal et al. 1996;Planer-Friedrich et al. 2012). ...
... mg/L during pre-monsoon and post-monsoon in higher depth deep aquifer (< 106 m), respectively. These results clearly indicate that shallow aquifers are more vulnerable than deeper aquifer (Kulkarni et al. 2018;Majumdar et al. 2016;Mandal et al. 1996). The existence of a clay layer within the aquifer may be responsible for the existence of As in groundwater (Liu and Wu 2019). ...
Geogenic arsenic is a metabolic hazard to global citizens, due to its presence in most of the rocks. Natural processes such as percolation of rainwater through soil layer and water–rock interaction in weathering process principally lead to the dissolution of arsenic-bearing minerals in the aquifer system. In the present study, arsenic (As)-contaminated groundwater was analyzed covering all blocks (26 blocks) of Murshidabad District, West Bengal, India. Principally, the study focused on the assessment of groundwater quality with respect to arsenic along with other metal ions such as iron, manganese, cadmium and selenium. Tube well water samples (N = 348) were collected during pre- and post-monsoon seasons. The spatial distribution of arsenic levels ranges from 0.086 to 0.513 mg/L in pre-monsoon and 0.059–0.431 mg/L in post-monsoon, which indicates that all groundwater samples of the Murshidabad District exceeds the WHO’s permissible limit of arsenic (0.01 mg/L). Water quality index (WQI) data suggested that 5.74% and 10.3% samples are suitable for drinking purpose in the pre-monsoon and post-monsoon season, respectively. Availability of cations are as follows: Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ , and anions as: SO4²⁻ > HCO³⁻ > Cl⁻ > F⁻ > NO³⁻ in both pre-monsoon and post-monsoon seasons. Human health risk due to consumption of groundwater was assessed through USEPA designed methods as follows—hazard quotient (HQ), hazard index (HI), average daily dose of both direct ingestion of groundwater and dermal absorption of groundwater (ADDIngestion, ADDDermal absorption), and exposure frequency (EF). Thus, carcinogenic risk (CR) and non-carcinogenic risk (NCR) were determined. Results revealed that 29% and 37% of inhabitants suffered from carcinogenic and non-carcinogenic risk, respectively. On the basis of occurrence, spatial distribution and health risk assessment results of the targeted area can be marked as a moderate- to high-risk zone. The said zones need special attention for protection of public health.
... In the Ganga plain, groundwater can naturally contain harmful concentrations of arsenic, posing serious health risks to those who rely on it for consumption. Nearly four decades have elapsed since arsenic poisoning was first reported in the 1980s in West Bengal, India, with subsequent discoveries in other South Asian countries (Smith et al., 2000;Mandal et al., 1996). Despite this passage of time, it continues to pose a serious health concern in the region through the contamination of drinking water and the food chain (Islam et al., 2023;Ogata et al., 2020;Khan et al., 2023;Sarkar et al., 2022). ...
... Arsenic is hypothesized to be mobilized by microbially mediated 57,149,240 , redox-dominated dissolution of metal (oxyhydr)oxides 47,112,117,127,148 existing mostly as surface coatings on finer-grained sediments 146,234,242 and accentuated by massive irrigation pumping 118,165,182,185,190,191 . Earlier plausible hypotheses that were unsupported by ground observations suggested possible As release from the oxidation of sulfide minerals 243 and competitive ion exchange with dissolved phosphate from fertilizer 244 . The As fate is influenced by local-scale Fe-S-C cycling 111,112,146,148 under disequilibrium redox conditions 137 , potentially driven by methanogenesis from peat deposits 119 , dispersed sedimentary organic matter or surface-derived dissolved organic matter 150,162,175 . ...
Geogenic groundwater contaminants (GGCs) affect drinking-water availability and safety, with up to 60% of groundwater sources in some regions contaminated by more than recommended concentrations. As a result, an estimated 300-500 million people are at risk of severe health impacts and premature mortality. In this Review, we discuss the sources, occurrences and cycling of arsenic, fluoride, selenium and uranium, which are GGCs with widespread distribution and/or high toxicity. The global distribution of GGCs is controlled by basin geology and tectonics, with GGC enrichment in both orogenic systems and cratonic basement rocks. This regional distribution is broadly influenced by climate, geomorphology and hydrogeochemical evolution along groundwater flow paths. GGC distribution is locally heterogeneous and affected by in situ lithology, groundwater flow and water-rock interactions. Local biogeochemical cycling also determines GGC concentrations, as arsenic, selenium and uranium mobilizations are strongly redox-dependent. Increasing groundwater extraction and land-use changes are likely to modify GGC distribution and extent, potentially exacerbating human exposure to GGCs, but the net impact of these activities is unknown. Integration of science, policy, community involvement programmes and technological interventions is needed to manage GGC-enriched groundwater and ensure equitable access to clean water. Sections
... It may be noted that nine districts of Bengal Delta, West Bengal (viz. Malda, Murshidabad, Nadia, North 24-parganas, Kolkata, South 24-parganas, Barddhaman, Hoogly and Howrah) have As contamination in groundwater (Acharyya & Shah 2010;Bhattacharya et al., 1997;Chakraborti et al., 2009;Mandal et al., 1996). The upper permissible limit of As in drinking water is 10 mg/L as per WHO guidelines, which has been endorsed by Bureau of Indian Standards (BIS). ...
... As a result, human being are prone to several health-related problems such as hyperkeratosis, leuco-melanosis, gangrene, keratosis, melanosis, nonpetting edema, skin cancer and dorsum. Humans exposed to chronic arsenic toxicity develop different disorders in the biological system such as the respiratory, renal, digestive, hematopoietic, cardiovascular, reproductive, endocrine, and neurological, and eventually bring cancer [101,102] as highlighted in Fig. 8. Long standing experience to inorganic arsenic greater than 0.05 mg/L in humans results in arsenicosis, a general high and thus managed on top of ROS, a significant booster of cellular injury [87][88][89]. ...
Arsenic, a metalloid that exists by nature, reaches the earth either by natural or anthropogenic events and is considered an emerging pollutant. The existence of arsenic in soil systems is a fate to the environment since it is mobile and being transported to other systems because of its bioavailability and speciation process. Arsenic transformation in the soil and its thorough understanding of how it enters plant systems are crucial. Notably, transporters are responsible for most of the arsenic that enters the plant system. Consumption of crops or animals and drinking water polluted with arsenic are the prime factors in transmitting arsenic to people. Severe adverse effects on humans arise as an outcome of long-term contact with arsenic-rich foodstuff and water. An effort has been made to outline the several sources and their dynamics in the surroundings and health impact on humans in this review. In addition, various strategies have been practiced to remove arsenic in the soil and water systems is also addressed.
Graphical Abstract
... Continuing on our research efforts we have added more arsenic-affected areas to our list. In 1996 we reported (Mandal et al. 1996) 830 villages from 58 police station zones and eight arsenic districts of West Bengal to be reeling under the arsenic crisis. The eight identified districts were Malda, Murshidabad, Bardhaman, Nadia, Howrah, Hooghly, North 24-Parganas and South 24-Parganas. ...
... μg L −1 which is quite dangerous for human health. Six years survey on more than 20,000 samples from seven districts of West Bengal (including Purbasthali, Bardhaman), Mandal et al., in (1996) recovered the truth on arsenic availabilities in the groundwater. They also mentioned that more than 2,00,000 people are severely under attack to this carcinogen. ...
In this study, arsenic tolerating bacteria Bacillus pacificus(AKS1a) was isolated from arsenic contaminated groundwater of Purbasthali, Purba Bardhaman, West Bengal, India and its bioremediation potential was preliminary screened. This multimetal resistant strain was able to grow against more than 20 mM arsenate and 10 mM arsenite salts. The genome was more than 5.16 Mb in length, with an average of around 35.2% GC content, bearing 5403 protein coding genes. Arsenic resistant genes like arsC, arsB, arsR, etc. were also identified. Rapid Annotation using Subsystem Technology (RAST) identified 328 subsystems within the genome. Presence of six Genomic Islands (GIs) and five phage virus genomic parts indicated its ecological adaptations to overcome environmental stresses. The production of about 415 μg mL−1 indole acetic acid (IAA), 258.0 μg mL−1 gibberellic acid (GA), and 183 μg mL−1 proline by the bacterium, along with nitrogen fixation ability under in-vitro conditions, indicate its plant growth promoting potential. This was further confirmed through rice seedling growth enhancement under arsenic stress. Beside arsenite oxidation to arsenate, its arsenic adsorption property was confirmed through X-ray Fluorescence spectroscopy (XRF), Fourier Transform Infrared spectroscopy (FTIR), and Energy Dispersive X-ray spectroscopic (EDS) Analysis. Genomic comparisons among 25 different strains of B. pacificus showed that there are tremendous genetic differences in respect to their accessory genome content. In future, this strain can be applied as biofertilizer or biostimulant for improving rice plant growth.
... Presence of As in groundwater in Bangladesh was first identified by the Department of Public Health Engineering (DPHE) in 1993 [19]. Arsenic concentration in the HTWs frequently exceeds both World Health Organization (WHO) [25] and the Bangladesh Drinking Water Standards (BDWS) provisional guideline concentration for As in drinking water, 10 µg/L and 50 µg/L respectively; and often As concentrations reach mg/L levels [24,26]. ...
Naturally occurring groundwater arsenic contamination is a major problem in Narail, Bangladesh. Analyses of 32 groundwater samples showed arsenic concentrations ranged 20.33–158.90 µg/L. Relatively deeper aquifer (>45 m depth) in addition to arsenic, is contaminated with substantial amount of salinity. Electrical conductivity (EC) ranged 1.01–7.90 mS/cm indicating the enormity of salinity. The groundwater is mainly Na–Cl to Na–HCO3 type, and is SO4 limited. This research demonstrates the effectiveness of two mitigation techniques (i) managed aquifer recharge (MAR) and (ii) sub-surface arsenic removal (SAR) for in-situ salinity and arsenic treatment of contaminated groundwater. A two-year long experiment revealed that the MAR system was effective in reducing both salinity and arsenic. Groundwater EC reduced 72–81% from an initial value of 3.4 mS/cm to less than 1 mS/cm. Arsenic concentration dropped below 50 µg/L from an initial concentration of 100 µg/L. The SAR system reduced arsenic concentration below 50 µg/L from an initial concentration of 100 µg/L. The system was capable of yielding 1500 liters of arsenic safe water when injected volume of oxygen saturated water was 2000 liters indicating 70–80% recovery. Both systems can provide 1000 liters of safe drinking water at a cost of $2.00.
... Moderate and severe forms of keratosis (hyperkeratosis) appear as large nodular keratoses (corn-like protrusion) which are readily visible [2,4,50]. Arsenic-induced dermal toxicity progresses from melanosis to keratosis and hyperkeratosis [1,6,53]. A physician team carefully checked the different parts of each participant's body and identified skin lesions. ...
Arsenic is a potent environmental toxicant and human carcinogen. Skin lesions are the most common manifestations of chronic exposure to arsenic. Advanced-stage skin lesions, particularly hyperkeratosis have been recognized as precancerous diseases. However, the underlying mechanism of arsenic-induced skin lesions remains unknown. Periostin, a matricellular protein, is implicated in the pathogenesis of many forms of skin lesions. The objective of this study was to examine whether periostin is associated with arsenic-induced skin lesions. A total of 442 individuals from low- (n = 123) and high-arsenic exposure areas (n = 319) in rural Bangladesh were evaluated for the presence of arsenic-induced skin lesions (Yes/No). Participants with skin lesions were further categorized into two groups: early-stage skin lesions (melanosis and keratosis) and advanced-stage skin lesions (hyperkeratosis). Drinking water, hair, and nail arsenic concentrations were considered as the participants’ exposure levels. The higher levels of arsenic and serum periostin were significantly associated with skin lesions. Causal mediation analysis revealed the significant effect of arsenic on skin lesions through the mediator, periostin, suggesting that periostin contributes to the development of skin lesions. When skin lesion was used as a three-category outcome (none, early-stage, and advanced-stage skin lesions), higher serum periostin levels were significantly associated with both early-stage and advanced-stage skin lesions. Median (IQR) periostin levels were progressively increased with the increasing severity of skin lesions. Furthermore, there were general trends in increasing serum type 2 cytokines (IL-4, IL-5, IL-13, and eotaxin) and immunoglobulin E (IgE) levels with the progression of the disease. The median (IQR) of IL-4, IL-5, IL-13, eotaxin, and IgE levels were significantly higher in the early-and advanced-stage skin lesions compared to the group of participants without skin lesions. The results of this study suggest that periostin is implicated in the pathogenesis and progression of arsenic-induced skin lesions through the dysregulation of type 2 immune response.
... In the eastern region of India, paddy is cultivated throughout the year and has the highest intensity of rice cultivation. Mandal et al. (1996) stated that India and Bangladesh pursue two types of cultivation practice according to their seasonal rainfall pattern. In West Bengal, paddy cultivation mainly occurs in two different seasons, pre-monsoon (February to April) and monsoon (July to September), respectively. ...
Groundwater arsenic contamination has been a staggering issue for the last 45 years. When the contaminated water is used for irrigational activities, the problem aggravates. Bengal delta is mainly reliant on rice as the staple diet and its cultivation often requires irrigation water during summer due to scarcity of fresh water and insufficient rainfall. Therefore, in arsenic exposed area, the use of contaminated groundwater can introduce arsenic into the soil–plant system. Astonishingly, rice grain accumulates up to 10 times more arsenic than other regularly harvested crops and its accumulation differs with geographical location, rice variety, cultivars and cultivation season. Importantly, arsenic concentration of paddy is highly dependent on the primordial arsenic concentration in irrigation water and soil. Geographical attributes of an area are the most significant factors of arsenic content in rice grains, as they are the chief influencer of soil arsenic concentration. In this study, the contamination quotient of rice grain arsenic is determined by the average values from four sampling sites namely North 24-Parganas, Nadia, Kolkata and West Medinipur districts of West Bengal, India and the values are 300, 215, 190, and 137 µg/kg, respectively. Apart from geographical origin, rice grain arsenic concentration also differs with cultivar. So here, rice grains are classified into three different categories according to their arsenic accumulation and assimilation capacity. The maximum amount of rice cultivars in the entire study area are medium accumulators; range of arsenic concentration is > 100–300 µg/kg (n = 45) with an average value of 178 ± 41 µg/kg. Simultaneously, arsenic concentration of rice grain depends on various factors; however, variety is one of the key players. Parboiling with arsenic contaminated water act as a “factor enhancer” during this process in arsenic exposed area. Our study found that sunned rice grains contain lower arsenic (188 μg/kg) compared to the parboiled one (268 μg/kg). Concurrently, the fourth factor is cultivation season. In Bengal delta, paddy cultivation is practiced in two seasons: pre-monsoonal and monsoonal season. The data depicts that monsoonal grain contains lesser amount (224 ± 63 µg/kg) of arsenic than pre-monsoonal (528 ± 434 µg/kg) grain. This can be interpreted by the theory of dilution, because in monsoon season, rainwater mixes with the waterlogged irrigation field and dilutes the initial arsenic concentration. Transport of arsenic-contaminated rice grain grown in arsenic endemic areas to the non-endemic sites and consequent dietary intakes leads to great threats for the local inhabitants.
... The alluvial stretch extends from Rajasthan through the middle basin covering Haryana, Delhi, Uttar Pradesh, and Bihar up to West Bengal (Figure 3e). Iron oxides promote arsenic mobilization by forming arseniccontaining pyrites that later undergo oxidation and discharge arsenic by reducing iron oxyhydroxide under anoxic conditions [73,74]. Hence, oxidation of pyrites and reductive dissolution of iron oxides and hydroxides during sediment burial apparently favoured leaching of arsenic from the soil [67,75]. ...
Elevated arsenic concentrations in groundwater in the Ganga–Brahmaputra–Meghna (GBM) river basin of India has created an alarming situation. Considering that India is one of the largest consumers of groundwater for a variety of uses such as drinking, irrigation, and industry, it is imperative to determine arsenic occurrence and hazard for sustainable groundwater management. The current study focused on the evaluation of arsenic occurrence and groundwater arsenic hazard for the Ganga basin employing Analytical Hierarchy Process (AHP) and Frequency Ratio (FR) models. Furthermore, arsenic hazard maps were prepared using a Kriging interpolation method and with overlay analysis in the GIS platform based on the available secondary datasets. Both models generated satisfactory results with minimum differences. The highest hazard likelihood has been displayed around and along the Ganges River. Most of the Uttar Pradesh and Bihar; and parts of Rajasthan, Chhattisgarh, Jharkhand, Madhya Pradesh, and eastern and western regions of West Bengal show a high arsenic hazard. More discrete results were rendered by the AHP model. Validation of arsenic hazard maps was performed through evaluating the Area Under Receiver Operating Characteristics metric (AUROC), where AUC values for both models ranged from 0.7 to 0.8. Furthermore, the final output was also validated against the primary arsenic data generated through field sampling for the districts of two states, viz Bihar (2019) and Uttar Pradesh (2021). Both models showed good accuracy in the spatial prediction of arsenic hazard.
... Patients with white melanin and hyper circulation were found in many cases. The chronic exposure to the organism also causes many disorders on various biological systems for example, the stomach related framework, respiratory system, cardiovascular system, hematopoietic system, endocrine system, renal system, sensory system and regenerative system which prompts cancer disease [57]. The nutrition deficiency is an important promoter of arsenic, especially for younger women [58]. ...
Contamination of arsenic (As) in water, especially groundwater, has been recognized as a major problem across the world. The presence of arsenic in groundwater has become a global problem in the past decades. Health risks have also been reported for many years. Different areas of the world are affected by arsenic contamination of groundwater, the largest population at risk in Bangladesh, followed by West Bengal in India. Arsenic concentrations in drinking water cause severe health effects on human, more than 150 million people worldwide. The current drinking water standard regulation has become strict and requires a reduction in arsenic content. Therefore, the treatment of arsenic contaminants can be the only effective option to reduce health risks. This review paper briefly describes arsenic sources, arsenic chemistry, arsenic contamination in groundwater, its impact on human health and many conventional as well as advanced techniques that are used to remove arsenic from water.
... Arsenic sulfides might already in use as pesticides in China as early as 900 A.D. (Frouin H 2010). Arsenic contaminate in drinking water sources from natural deposits, from agricultural and industrial practices (Smith et al. 2000). Arsenic contaminated water is one of the major cause of death in number of parts of the world, especially in India and Bangladesh (Chatterjee et al. 1995). It causes a disease called Arsenicosis. ...
Healthcare waste includes the waste generated by healthcare facilities, medical laboratories and biomedical research facilities. Improper treatment of this waste stands severe risks of disease transmission to waste pickers, waste workers, health workers, patients, and the community in general through exposure to infectious agents. Poor management of the waste emits destructive and deleterious contaminants into society. The WHO has established guidelines for management of healthcare waste. These guidelines are assisting to manage the highly contagious healthcare waste resulting from the current pandemic. Proper healthcare waste management may add value by lower
the spread of the COVID-19 virus and raising the recyclability of materials instead of sending them to landfill. Disinfecting and sorting out healthcare waste facilitate sustainable management and enable their utilization for valuable purposes. This review discusses the various healthcare solid waste management strategies and the possible solutions for overcoming these challenges. It also provides useful knowledge’s into healthcare solid waste management scenarios during the COVID-19 pandemic and a possible way forward.
... The As concentration in groundwater vary globally due to various sources of arsenic. Higher As concentration (0-48 mg/l) has been recorded from Western USA because of prevailing geochemical environments (Welch et al. 1988), followed by India (0-23.08 mg/l) due to As rich sediment and pesticide production (Mandal et al. 1996;Ghosh et al. 2015a). Notably the Bengal Delta Plains (BDP) spanning across Eastern India and Bangladesh have arsenic-contaminated aquifers mainly due to geogenic activity (Smedley and Kinniburgh 2002) and also represent one of the worst affected regions globally (Mukherjee et al. 2009;Ghosh et al. 2014;Shrivastava et al. 2015;Ghosh et al. 2018). ...
Arsenic (As) contamination is a major global environmental concern with widespread effects on health of living organisms including humans. In this review, the occurrence (sources and forms) of As representing diverse aquatic habitats ranging from groundwater to marine environment has been detailed. We have provided a mechanistic synopsis on direct or indirect effects of As on different organismal groups spanning from bacteria, algae, phytoplankton, zooplankton and higher trophic levels based on a review of large number of available literature. In particular, special emphasis has been laid on finfishes and shellfishes which are routinely consumed by humans. As part of this review, we have also provided an overview of the broadly used methods that have been employed to detect As across ecosystems and organismal groups. We also report that the use of As metabolites as an index for tracking As tot exposure in humans require more global attention. Besides, in this review we have also highlighted the need to integrate ‘omics’ based approaches, integration of third and fourth generation sequencing technologies for effective pan-geographical monitoring of human gut microbiome so as to understand effects and resulting consequences of As bioaccumulation.
... Arsenic is a highly poisonous and carcinogenic compound and has been reported in the groundwater of the Indian state of West Bengal [47]. The concentration of As in the study site ranged from below detectable level to 0.05 mg/L. ...
... In fact some villages of Orissa and Assam have content up to 10 mg/l. Even arsenic contamination is reported in West Bengal since long which ends up causing arsenical wounds in skin of people living in the state [6]. There is a salinity of even greater than 1500 mg/l in most of the arid and remote areas of India and people face issues due to scarcity of fresh water and contamination in available water [7]. ...
Water has an influential lead when talking about the overall prudence round the globe. The aspects of quality and abundance of water in progressive countries is a convincing hazard globally to the prosperity of people. There are many reasons hampering the quality of water like intrusion from sea water, toxic effluent discharges from industries, improper solid waste management which leads to polluting the ground water up to kilometers of stretch due to release of toxic leachate, agricultural washes containing pesticides and various hazardous chemicals and most prominent being the human settlements near the water bodies which over all diminishes the quality of water and is posing a severe threat to the living masses as wate r is the only solvent fulfilling the entire needs on planet earth for the survival of life. This paper provides an outline of various water treatment devices and techniques which can give an outline of how to manage the quality of wastewater.
... On the eastern bank of river Bhagirathi, there were comparatively lower elevations above the mean sea level (well-marked in Fig. 1 of the study area), progressively leading to the formation of fluvial deltaic deposition towards the eastern bank, which creates a conducive scenario for the formation of Holocene aquifer (which is the extensive alluvial deposition of river Bhagirathi, i.e. Quaternary alluvium, cause enrichment of organic matter which consequently creates the hospitable situation for the dissolution of arsenic bearing minerals, also confirmed by Mukherjee et al. (2006), Das et al. (1996), Chakraborti et al. (2001), and Sarkar and Paul (2016). The fluvio-deltaic formation is the continuous process on the lower elevated regions of river Bhagirathi, which causes hydro-stratigraphic deposition of continuous thick sands layers on clay layers and facilitates vertical mixing of groundwater (Mukherjee et al. 2011) while in contrast on the western bank of river Bhagirathi; there was thinner sand deposition on clay layers, inhibiting vertical mixing (Mukherjee et al. 2007a). ...
This study was conducted to inspect the spatial distribution, source identification, and risk assessment of groundwater arsenic (As) in different blocks that lie on the opposite banks of river Bhagirathi (a distributary of river Ganges), Murshidabad, West Bengal, India. It has been observed that the blocks that lie towards the eastern bank of river Bhagirathi have elevated arsenic and comparatively more reducing groundwater (lower oxidation–reduction potential and high iron). About 66% of groundwater samples across the district have arsenic concentration higher than the World Health Organization (WHO) permissible limit. Speciation of groundwater arsenic reveals that about 90% of arsenic species were present as arsenic (III). Further, principal component analysis (PCA) was employed to identify the controlling factors that favor the release of arsenic. PC1 comprises EC, TDS, As, Fe, TOC, and HCO3⁻ with moderate loadings, which suggests microbially mediated degradation of organic matter (OM), helps in reductive dissolution of arsenic-bearing Fe–Mn oxyhydroxides. Results pointed out severe groundwater arsenic poisoning; hence, a health risk assessment was performed for the exposure of arsenic in groundwater, using incremental lifetime cancer risk (ILCR) models coupled with Monte Carlo simulations. On the eastern bank of river Bhagirathi, incremental lifetime cancer risk (ILCR) due to oral exposure (5th to 95th percentile values) ranged from 1.30538E − 04 to 9.31398E − 03 with a mean of 2.84194E − 03 for adults, which is 2841 times higher than the USEPA high safety risk guidelines of one in 1 million. The outcomes of the results will be useful for the policymakers and regulatory boards in defining the actual impact and deciding the pre-remediation goals.
Graphical abstract
... Inorganic occurrence in groundwater is a serious menace worldwide like flood and delta plains of Mekong River in Laos and Cambodia (Poyla et al., 2005). Indus river of Pakistan (Iqbal, 2001), Upper end of red river delta in Vietnam (Berg et al., 2001) and Irrawaddy delta in Myanmar (Mandal et al., 1996) including Gangetic basin (Nickson et al., 1998) Arsenic is introduced into the aquatic environment through natural and anthropogenic sources. However, majority of arsenic contamination is due to natural sources because arsenic is found as a major constituent in more than 200 minerals (Petrusevaki et al., 2007). ...
Arsenic, chromium and organic dyes are the prominent carcinogenic agents, posing a serious health hazard. In current scenario, groundwater as well as surface water mostly contaminated by chemical complexes of As (III), Cr (VI) and organic dyes, these are leading hazardous threat to eco-system. Several mitigation techniques of As (III), Cr (VI) and organic dyes are available but efforts are going on to devise a novel method of removal of these toxicants. This review takes into account all the recent advances in the detoxification of contaminated water exploring removal mechanism by biosorption and bioaccumulation. The possibility of the removal of toxic heavy metals from an aqueous medium by plant and bacterial biomass has been discussed. Now a days, bioaccumulation and biosorption from plants and microbial sources has emerged as simple, effective and eco-friendly techniques for decontamination of these chemical compounds from water resources at very low cost. Many agricultural products and solid wastes have also been found suitable decontaminant of toxic heavy metals and dyes. A wide spectrum of medicinal and aromatic plants as well as aquatic plants available in abundance may also be utilized as potential remover of As (III), Cr (VI) and organic dyes. This article explained mechanism and application on detail aspects of bioremediation technology including conventional techniques with recent development. This review shows the trends and development of mitigation stretagies by bioremediation with latest updates.
... So there must be a probability of transmission of arsenic and other heavy metals from soil to herbal plant as well as irrigated crops in metal contaminated site. Mandal et al., (1996) reported the presence of As is above the maximum limit as recommended by the WHO (0.01 mg/l) (WHO, 2001) in ground water in Murshidabad district of West Bengal, India. Traditionally, rural population of this district used various medicinal plants as Kavirajee directly for different primary health care. ...
Murshidabad district is one of the most highly Arsenic (As) prone areas of West Bengal, India. The predominantly rural population of this district greatly depends on traditionally used medicinal plants for treatment of various ailments and subjected to risk of arsenic contamination. The present study revealed that some naturally grown medicinal plants in this district were found to have the alarming level of concentration of arsenic and other metals (Fe, Cu) contamination. So, there should be raised more consciousness on the toxic metal contamination of medicinal plants specifically, collected from contaminated sites.
... The Bengal Delta plain of India and Bangladesh in Southeast Asia is one of the major arsenic contaminated regions globally. Various hydrochemical studies carried out in the Ganga-Meghna-Brahmaputra (GMB) river basin reveal the provenience of arsenic to be of geogenic inception [32,33], that perpetuates and exacerbates spontaneously under natal hydro-geological processes [34,35]. Oxidation and reduction hypotheses are the most discussed theories to explain the genesis of arsenic mobilization in the subsurface of the GMB basin, with the latter acquiring more scientific acceptance in academia [36][37][38][39]. ...
... Several studies (Concha et al., 1998) have shown that children are at higher risk of arsenic exposure. Chronic arsenic exposure causes a characteristic pattern of dermal effects that might start with melanosis (pigmentation) to keratosis and hyperkeratosis (Mandal et al., 1996). It has been noticed that when keratosis and melanosis appear together, they point to arsenical toxicity. ...
... As is most hazardous metaloid in the environment and about 45 million people are facing the risk in South-East Asia (Ravenscroft et al. 2009) while about ~ 150 million people are affected at global level (Ishikawa et al. 2019). In India, the permissible limit of As in water is 10 µg L −1 while its concentration varied from 50 to 23, 080 mg L −1 at As polluted sites in Kolkata, India (Mandal et al. 1996). Biswas et al. (2014) reported the variation in level of As in drinking water from summer to winter season (26 μg L −1 in summer, 6 μg L −1 in winter) at Nadia, West Bengal. ...
The present study assessed the effect of α-ketoglutarate supplementation on Solanum melongena L. seedlings grown under As stress by evaluating growth performance, photosynthetic pigments, carbonic anhydrase activity, photochemistry of PSII, nitrogen metabolism and oxidative stress. Growth, pigment contents, photosynthetic oxygen yield and carbonic anhydrase activity declined with AsV stress in dose dependent manner. As compared to control, As1 (5 µM As) and As2 (25 µM As) caused decline in fresh weight by 13 and 29% and dry weight by 14 and 39%, respectively. Furthermore, photochemistry of PSII parameters as quantum yield of primary photochemistry, yield of electron transport per trapped excitation, the quantum yield of electron transport and performance index of PSII declined with AsV stress while parameters related to energy fluxes per reaction center were enhanced. Not withstanding to this, respiration rate and ammonium content enhanced significantly due to more accumulation of As content in test seedlings. The As accumulation at As1 and As2 treated seedlings was found to be 39.75 ± 0.69 and 158.62 ± 2.75 µg As g−1 DW in root and 30.93 ± 0.54 and 141.37 ± 2.45 µg As g−1 DW in shoot, respectively. In addition, nitrate and ammonium assimilating enzymes: nitrate reductase, nitrite reductase, glutamine synthetase and glutamate synthase activity were adversely affected by AsV stress while glutamate dehydrogenase activity showed reverse trend. Such damaging effect of AsV could be due to enhanced oxidative stress as evidenced by increased SOR, H2O2 and MDA equivalents contents and electrolyte leakage in turn. However, negative effects of AsV on these parameters were significantly mitigated by α-Ketoglutarate, therefore, considerable improvement in growth performance of S. melongena seedlings was noticed. The findings suggest that α-Ketoglutarate, a key intermediate of the Krebs cycle and nitrogen metabolism reduces the AsV toxicity in S. melongena L. seedlings by downregulating As accumulation and oxidative stress biomarkers, activation of antioxidant defense system which collectively protect PSII photochemistry leading to improved growth in S. melongena seedlings.
... Arsenic contamination of groundwater is a serious problem in many countries, especially in Taiwan [1], India [2], and Bangladesh [3,4], and it causes disorders such as skin lesions, cancers (skin, lung, liver, bladder, kidney, and prostate), respiratory complications, and neurological complications in humans [5,6]. Arsenic has several valency states, including -3, 0, +3, and +5. ...
Arsenic contamination of groundwater is a serious issue in many countries. We investigated the removal mechanism of arsenite (As(III)) through coprecipitation with ferrihydrite to establish an optimum wastewater treatment method. We conducted adsorption and coprecipitation experiments with different As/Fe molar ratios to identify the differences between the adsorption and coprecipitation processes. Precipitates from these experiments were analyzed by using X-ray diffraction and X-ray absorption fine structure analysis to determine local structural changes of ferrihydrite during coprecipitation. As(III) removal via coprecipitation with ferrihydrite was caused by surface complexation at a lower initial As/Fe molar ratio (< 1.0). Surface complexation and amplification of the octahedral structure of the ferrihydrite were the removal mechanisms at higher initial As/Fe molar ratios (> 1.0). Our results contribute to developing a more efficient wastewater treatment method for As(III) removal.
... Studies have shown the occurrence of a few cases of skin cancer patients extremely affected by As(III) and As(V) (Hsueh et al. 1995). Long-term exposure to inorganic arsenic disrupts the functioning of various organ systems like the respiratory system, digestive system, cardiovascular system, endocrine system, hematopoietic system, renal system, and reproductive system, which eventually leads to metastasis (Maharjan et al. 2005;Mandal et al. 1996). The World Health Organization (WHO) estimated that 5-10 years of exposure to inorganic arsenic may pose severe health effects in human beings (Hong et al. 2014). ...
The contamination of terrestrial and aquatic ecosystems by arsenic (As) is a very sensitive environmental issue due to its adverse impact on organisms. Although arsenic contamination is not only of anthropogenic origin, the problem of arsenic contamination in water sources in many areas has been considered calamitous because of its significant risk to different organisms. Many of the organisms are already suffering from the irreversible effects of arsenic poisoning. The disposal of industrial and mining waste has led to extensive contamination of land and water resources. It also causes a potential problem for food chain contamination. Awareness of arsenic poisoning to the mass majority of people has led to the development of efficient remediation technologies for its mitigation. There are many strategies for remediation such as coagulation‐flocculation, membrane techniques, nanoparticles, and many more. In this chapter, different sources of arsenic contamination, health effects, and important management strategies currently being practiced for arsenic‐contaminated areas (surface and groundwater) are shown. The chapter concludes with different remediation techniques for the removal of arsenic contaminants from water systems, and some are evolving as alternative green techniques.
... The microbial-mediated reductive dissolution of Fe(III)-oxyhydroxides is the main mobilization pathways of arsenic mobilization in the Bengal basin (Bhattacharya et al. 1997;Biswas et al. 2014;McArthur et al. 2004McArthur et al. , 2012Islam et al. 2004;Kumar et al. 2018). The arsenic-contaminated areas are mainly situated to the eastern wing of the Bhagirathi River (the lower stretch of the regional river the Ganges) which comprises Holocene sediments derived from the Himalayan orogeny with the rivers originated up there from different glaciers (McArthur et al. 2001;Mandal et al. 1996;Nickson et al. 1998). The arsenic-enriched groundwater is mostly constrained to the Holocene aquifers of shallow depth (< 50 m) (Mukherjee and Bhattacharya 2001;Ahmed et al. 2001). ...
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.
... Mandal et al., 1996;Maharjan et al., 2005 در آرسنیک وجود ،) راجناندگان منطقه در موجود گرانیت سنگ در رآلگارد کانی ...
There are many springs in Iran that are contaminated by arsenic and therefore are not suitable for drinking purposes. Garu spring around Masjed Soleyman city is an indicator of such springs. In order to study the concentration of arsenic, 20 samples from spring and Asmari anticline observation wells were collected. Concentration of major and trace elements in the samples were measured. ICP-OES studies were carried out on 3 samples of the surrounding formation. The results showed that Garu spring has arsenic levels higher than 10ppb. Hydrochemical and statistical analyzes of water samples and sediment as well as significant correlation of arsenic with main cations, (i.e. Nickel and Vanadium) shows that anthropogenic factors do not have an effect on the amount of arsenic. It is found, that the origin of arsenic is geogenic (Gachsaran formation and oil brine influx). The mechanism of arsenic mobility during the wet season is the anaerobic respiration of Fe+3 reducing bacteria. Whereas, in the dry season, the environment is further reduced, as a result activity of the SRB and IRB in the span of springs leads to the reduction of iron by sulfide from sulfate respiration, this causes arsenic deposition. Also, gas chromatography analysis of the oil presented in spring shows that H2S is the result of thermochemical reduction of sulfate in carbonate reservoirs. According to the results of this study, the use of water resources in the region threatens the health of the inhabitants of the region, and arsenic removal methods should be used.
While Arsenate [As (V)] is the predominant species under aerobic conditions (Xu et al., Environ Sci Technol 42:5574–5579, 2008; Li et al., Environ Sci Technol 43:3778–3783, 2009b); in soil solutions, it may be as high as 5–20% (Khan et al., Environ Sci Technol 44:8515–8521, 2010), under typical flood conditions. Arsenic contamination of groundwater is a geogenic process. Oxidation of arsenopyrites or reduction of ferric oxyhydroxide or both forms an important pathway for As release in the groundwater. Iron and arsenic-bearing minerals formed in situ or brought along by rivers, combined with sulphur and form arsenopyrite (FeAsS).
Heavy metals and metalloids (cumulatively referred to as metal(loid)s) are ubiquitous in the environment. They originate from Earth’s crust, and their traces are present in all the environmental compartments. However, the concentration of many toxic heavy metal(loid)s has reached to a level causing serious health effects on humans. The sources and level of contamination of arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) in water, soil, and food commodities have been discussed in details in the previous chapter. In the current chapter, the common and specific mode of toxicity through chronic dietary exposure of these priority heavy metal(loid)s to humans and target organs/systems has been discussed. The conventional and recent developments in mitigation techniques of these metal(loid)s from water and soil have also been included.
This paper offers an extensive examination of studies published in the recent past and highlights the documented issues surrounding groundwater pollution, its sources, and distribution worldwide. The depletion of groundwater resources and the deteriorating overall quality present a significant cause for concern, particularly as a large human population relies on groundwater as a drinking water source. The review focuses on various factors contributing to groundwater pollution, including anthropogenic activities, hydro climatological influences, and natural processes. Special attention is given to organic contaminants such as pesticides, herbicides, and emerging pollutants, which have been found to have a substantial impact on groundwater quality. Additionally, the review covers pollution caused by inorganic pollutants like arsenic and other heavy metals, with a particular emphasis on regions experiencing a higher incidence of these contaminants in groundwater. Furthermore, the paper includes a compilation of studies that highlight the increased occurrence of waterborne illnesses resulting from fecal and microbial contamination, often caused by inadequate sanitary practices. To provide a comprehensive understanding of the global groundwater pollution problem, the review also encompasses an examination of contaminants like fluoride and nitrate.
Arsenic, Antimony, and Bismuth are members of Group V of the Periodic Table of Elements. These elements have been used for a variety of medicinal and pest control purposes over a number of centuries. They have also been used in metallic alloys and in the production of III–V semiconductors to increase electronic speeds of computer chips. Arsenicals are largely metabolized by methylation pathways and bismuth is known to induce the metal‐binding protein metallothionein and to form electron–dense cytoplasmic and intranuclear inclusion bodies.
Deterioration of groundwater quality is a long-term incident which leads unending vulnerability of groundwater. The present work was carried out in Murshidabad District, West Bengal, India to assess groundwater vulnerability due to elevated arsenic (As) and other heavy metal contamination in this area. The geographic distribution of arsenic and other heavy metals including physicochemical parameters of groundwater (in both pre-monsoon and post-monsoon season) and different physical factors were performed. GIS-machine learning model such as support vector machine (SVM), random forest (RF) and support vector regression (SVR) were used for this study. Results revealed that, the concentration of groundwater arsenic compasses from 0.093 to 0.448 mg/L in pre-monsoon and 0.078 to 0.539 mg/L in post-monsoon throughout the district; which indicate that all water samples of the Murshidabad District exceed the WHO's permissible limit (0.01 mg/L). The GIS-machine learning model outcomes states the values of area under the curve (AUC) of SVR, RF and SVM are 0.923, 0.901 and 0.897 (training datasets) and 0.910, 0.899 and 0.891 (validation datasets), respectively. Hence, "support vector regression" model is best fitted to predict the arsenic vulnerable zones of Murshidabad District. Then again, groundwater flow paths and arsenic transport was assessed by three dimensions underlying transport model (MODPATH). The particles discharging trends clearly revealed that the Holocene age aquifers are major contributor of As than Pleistocene age aquifers and this may be the main cause of As vulnerability of both northeast and southwest parts of Murshidabad District. Therefore, special attention should be paid on the predicted vulnerable areas for the safeguard of the public health. Moreover, this study can help to make a proper framework towards sustainable groundwater management.
Water resources of Pakistan are seriously depleting due to mismanagement. One of the major issues in the depletion of water resources in Pakistan which makes water not assessable to use is its contamination. The issue of arsenic contamination has emerged as a serious health concern in Pakistan. Pakistani population is exposed not only to toxic but poisonous levels of arsenic contamination. Only in Punjab province more than 20% population is exposed to arsenic levels of more than 10 ppb out of which 3% are exposed to more than 50 ppb levels of arsenic contamination. Various studies have shown the arsenic contamination in both shallow and deep aquifers. This chapter will give a comprehensive overview of arsenic contamination in water resources of Pakistan, their associated health risks, and possible remediation strategies to reduce exposure of arsenic contamination in Pakistani population.KeywordsContaminationArsenicWater resourcesHealthDiseases
The ubiquitous metalloid Arsenic (As) is naturally present in the different ecosystem. The high level of metalloid arsenic in water bodies are frequently being reported from different parts of the globe in the recent past mainly due to anthropogenic activity. Arsenic poisoning is well known for affecting the human health, causing a range of skin diseases, black foot, encephalopathy, peripheral neuropathy, and carcinogenicity. This chapter focuses on the various sources of arsenic contamination, diseases caused, and possible remediation strategy including phytoremediation for combating arsenic pollution, in brief.
Arsenic being a toxic metalloid has become a global health concern due to its increasing contamination in water, soil, and air. Contamination of arsenic is due to geological as well as anthropogenic activities that lead to health hazards for human beings through contaminated drinking water and food. Increasing human population and overexploitation of groundwater affect and change the geological processes of rocks in aquifers, which leads to arsenic contamination in water, especially groundwater. Particularly, inorganic arsenic, arsenate As(V), and arsenite As(III) are more predominant in the environment and affect plants and animals, including humans. Monitoring of arsenic contamination and estimation of its concentration in water will help in the investigation of contaminated sites and understanding its route, its fate in the environment. Further, arsenic accumulation in plant tissues growing in the contaminated area indicates the possible threat of biomagnification and related health risks in animals through food chain contamination. Understanding arsenic uptake, efflux pathways, and transporters in plants are important for assessing health hazards and developing mitigation strategies for health and environmental safety.
Groundwater is a vital resource that accounts for around 30% of the world’s freshwater resources. In arid and semi-arid zones,
the human dependency on groundwater is comparatively very high, and its quality signifcantly impacts human health. Both
anthropogenic and natural factors have led to changes in hydrodynamics of groundwater resources and water security issues in
various regions of the globe. Thus, the bibliometric search methods were conducted to assess the dynamics of “Groundwater
Research” in India based on scientifc literature published from 1989 to 2020. In this regard, the Web of Science Core Collection
database has been used to extract the literature amounting to 3848 document types. Analysis and mapping of the searched data
have been compiled using Microsoft Excel, bibliometrix R-Package Biblioshiny, BibExcel, HistCite and VOSviewer tools,
which enabled to assess of the development of the literature, identifcation of documents types, most prolifc authors, countries,
institutions, highly cited articles, productive journals, bibliographic coupling, keywords and hotspot topics. The signifcant
fndings highlight that the number of research publications has increased signifcantly over the last few decades in India to
promote groundwater scientifc study and research. The study highlight that the research articles are the most preferred document
type, and India’s collaboration in groundwater research is highest with the USA. The Journal of the Geological Society of India
is the most preferred journal for research publication and the highest count of publication contributions from the Indian Institutes
of Technologies. The present review study will assist institutions in providing the current “Groundwater Research” gap in the
country and will facilitate the future productive research output in groundwater research.
Contamination of arsenic (As) in groundwater has increased across the world with prominence in the middle- and low-income countries. The United Nations ‘Sustainable Development Goals’ (SDG's)- ‘good health and well-being’ (SDG 3) and ‘safe and clean water and sanitation for all’ (SDG 6), cannot be achieved without monitoring and remediating ‘As’ pollution in groundwater. Over 230 million people worldwide are affected due to arsenic-contaminated drinking water. More than 200 articles discussing the ‘As’ contamination, toxicity and cost effective technology were reviewed in this study focusing on economic status of the affected nation as per World bank report. Cost budget analysis suggested that chemical oxidation followed by precipitation (0. 043-0. 076 US$/m³), low cost adsorbent (0. 1 US$/m³), hybrid treatment technologies (0. 15-0. 17 US$/m³) and biological oxidation (0. 2 US$/m³) can be applied in low income countries through community based models to mitigate the health problem related to As contamination in order to achieve SDG 3 and SDG 6 targets. This study recommends further research on budget friendly ‘As’ remediation systems and policy level interventions in the affected nations to cater safe drinking water to all.
Heavy metal contamination in groundwater is a global health concern and its gravity is higher in India, as more than 80% of the rural and 50% of the urban population rely on it for drinking purposes. The present study comprehensively analysed the source, distribution pattern, and seasonal flux of heavy metals in the groundwater sources of Malappuram district, a coastal landmass in peninsular India, using multivariate statistics, pollution indices, and interpolation models in GIS. In three seasons, higher incidences of Pb, Ni and Cd and lower persistence of Zn and Cu were observed during the study period. Heavy metal Pollution Index (HPI) was highest during the pre-monsoon season as 57.57% of the samples were above the critical value. The Metal Index (MI) was higher in coastal areas and is linked to fluvial deposits. More than 77% of the samples were noted to be acidic in all the seasons due to geogenic influxes that accelerated the dissolution of toxic metals upon contact. The HPI interpolation model reveals less heavy metal contamination in the coastal plains, compared to midland and highland urban centres, indicating the least influence of terrain characteristics in the translocation of heavy metals in the groundwater sources.
In this study, tube well water, soil, crop, and vegetable were collected from agricultural field where irrigated with arsenic contaminated water. Estimation of total arsenic and other metals and metalloids in soil, vegetable, and paddy (rice & husk) samples by using ICP-MS after microwave digestion. But arsenic species in paddy (rice + husk), rice, husk, and vegetable by IC-ICP-MS after TFA extraction. Results show that the average arsenic concentration in contaminated soil, rice, and vegetable were 3.81, 3.62, and 5.66 times higher than the control samples, respectively. The overall observations indicated that arsenic concentration in vegetable and paddy were positively correlated with arsenic in soil. Also, for paddy arsenic concentration decreases shoot > seed (rice) > husk and in vegetables the distribution is leaf> stem > fruit. The regression analysis was carried out between arsenic and other metals in soil samples. However, no significant co-relation was observed between As & Mn, As & Cu, As & Ni, or As & Pb. But a significant (<0.05) positive correlation found between As & Zn (r =+0.763, p = 0.027) and also a strong negative correlation was observed between As & Hg (r = -0.802, p = 0.009). Arsenic along with Se, Mn, Cu, Hg, Pb & Ni were analyzed in rice & husk of 3 paddy samples cultivated with arsenic contaminated water. The regression analysis was carried out between arsenic and other metals. Linear regression shown negative correlation between As & Se (r= -0.999, p = 0.018), As & Pb (r = -0.992, p = 0.078) and positive correlation between As & Cu (r =+0.998, p = 0.03). But no satisfactory correction observed between As & Mn, As & Hg, and As & Ni. It has been observed selenium concentration decreases with increase arsenic concentration in both rice and husk, collected from As contaminated field in Bangladesh. This has also been observed in two vegetable samples those we had studied. All analyzed elements concentration (µg/gm) were less in “Kachu (Taro)” comparing “Data (Stem amaranth)” except arsenic. Arsenic was very high in “Kachu” comparing “Data” even though they were irrigated with same water containing arsenic 205 µg/L. The overall conclusion from arsenic species analysis in rice, paddy (rice + husk), and some vegetables are that inorganic arsenic is the dominating species of arsenic. It appears from all four-rice analysis that inorganic arsenic is the major portion of arsenic in rice. All four-husk analysis shows only presence of inorganic arsenic. No methylated form of arsenic was found in any husk samples, but arsenic species in a paddy (rice+ husk) sample shows high inorganic arsenic (76.46%) and 19.37% DMA & 4.23% MMA. It shows presence of inorganic arsenic & DMA, and possibility of an unknown arsenic species in Lady's Finger. It was very high arsenic concentration in a vegetable named “Kachu” which grows inside soil a popular food in West Bengal-India and Bangladesh. Most interesting, its inorganic arsenic concentration is quite high, but it has no detectable amount of methylated form of arsenic and possible of an unknown arsenic species. Rice and vegetable are the staple food for poor villagers of Bangladesh and West Bengal-India. This is true for the villagers in Kolsur gram-panchayet (G.P.) in Deganga block of North 24-Parganas district, West Bengal-India, where we studied for arsenic in soil, rice, and vegetable from 10 plots cultivated with arsenic contaminated water. From the results of total arsenic (drinking water + rice + vegetable + Pantavat (rice mixed with water) + water added for food preparation) body burden to North Kolsur villagers is 1185.0 µg for per adult per day and 653.2 µg for per child per day. Amount of arsenic coming from rice, vegetable, and water added for Pantavat and food preparation is 485 µg i.e., 41% of total for adult and 253.2 µg i.e., 38.8% for child, and from rice and vegetable 285 µg i.e., 24% of total for adult and 153.2 µg i.e., 23.4% for child (around age 10 years). Our findings show most of the arsenic coming from food is inorganic in nature. As toxicity of most of the organic arsenic compounds in food is less compared to inorganic arsenic. Therefore, compared to worldwide arsenic consumption from food, it appears Kolsur villagers are also consuming high amount of inorganic arsenic from food and vegetable, and people appears also at risk from arsenic in food. Kolsur village is an example of many such villages in West Bengal-India and Bangladesh. Further, products from arsenic irrigated water- soil system rich in arsenic are also coming to common marketplace far away from contaminated areas and even people who are not drinking arsenic contaminated water may get arsenic from food products produced from contaminated fields. In West Bengal-India and Bangladesh rice, vegetable, and other products are coming to cities (including Kolkata in West Bengal-India and Dhaka in Bangladesh) from villages and possibility that city people consuming arsenic contaminated products from contaminated areas cannot be ruled out. Abbreviation: IC-ICP-MS, Ion chromatography-inductively coupled plasma-Mass spectrophotometry; FI-HG-AAS, Flow injection-hydride generation -atomic absorption spectrometry Introduction In West Bengal-India out of its total 18 districts in 9 districts arsenic in groundwater has been found over 50 µg/L. Total area and population of these 9 districts are 38,865 km2 and 42.7 million (approx.), respectively while the area and population of West Bengal are 88,000 km2 and 68 million (approx.). This does not mean that 42.7 million people in these 9 districts are drinking arsenic contaminated water and will suffer from arsenic toxicity, but no doubt they are at risk. In 9 affected districts of West Bengal, approximately 6 million people are drinking arsenic contaminated water at levels >50 µg/L. For arsenical skin lesions, we examined approx. 86,000 people in 7 affected districts out of 9 and 8500 (9.8%) people were registered with arsenical skin lesions. But we expect, from extrapolation of our generated data that nearly 300,000 people may have arsenical skin lesions in West Bengal-India. State, West Bengal is prosperous in agriculture. The state has surplus food production and main crops are paddy and vegetable. Land of these 9 contaminated districts of West Bengal is very fertile and all are in recent gangetic deltaic plain. Major quantum of food production of West Bengal is coming from these 9 districts and tens of thousands of small and big diameter tube wells are in use for irrigation purpose. Plant needs a small fraction of the total water we pour to the field. Groundwater is considered to be the main source of water for agriculture and its use is increasing day by day. It has been noticed that even if surface water is available for irrigation from nearing source farmers are reluctant to use those sources if they must spend some extra money for this purpose. Except 5 months of rainy season (June-October) rest of the 7 months of the year farmers use groundwater for agriculture. Even during June to October if there are no rain farmers use groundwater. During 1996 it has been reported1 by School of Environmental Studies (SOES), Jadavpur University, and Kolkata that from a single Rural Water Supply Scheme (RWSS), Govt. of W. Bengal in Malda district, supplying water to a few villages, and 147.8 kg of arsenic came out during a year with groundwater. Therefore, it is expected that huge quantity of arsenic is falling on agricultural land from contaminated tube wells in use for irrigation. A follow-up study was made by SOES to know how much arsenic is falling on irrigated land in one year during cultivation from all 3200 tube wells that exist in the block Deganga of North 24-Parganas2. The basis of calculation was like this: 3200 shallow tube wells of 7 cm to 10 cm diameter were used in 1997 in Deganga block for agriculture and average discharge rate was 20 m3/hr. electric / diesel pumps (average 5HP) were used. These shallow tube wells used to run in average 7 hours per day for 7 months in a year. We had analyzed 597 irrigation tube wells out of total 3200. Out of those 597 tube wells, 574 tube wells contain arsenic ≥10 µg/L. The average arsenic concentration of the 574 tube wells was 70 µg/L (range 10 -840 µg/L). A calculation was made to know how much arsenic is falling on soil from 3200 tube wells based on measurement of 574 tube wells (total analyzed) and extrapolating to 3200. The overall result shows from the block Deganga alone 6.4 tons of arsenic is falling on agricultural land in one year from 3200 agriculture tube wells. Thus, it appears that in West Bengal-India and Bangladesh a few thousand tons of arsenic is falling on agricultural land in every year. Total arsenic contribution through food for many developed countries have been reported3. Although sea food contains mainly nontoxic organic forms of arsenic and rapidly excreted Figure 1. Location of Madaripur district of Bangladesh, and North 24-Parganas and Medinipur districts of India through urine, but other than sea food inorganic arsenic may be the major contribution of arsenic in many foods. A study from Canada4,5 indicates that arsenic content of many foods is mainly inorganic in nature and typically in the range 65-75%. US-EPA reported that percentage of inorganic arsenic in rice, vegetables and fruits are 35%, 5% and 10% respectively6. It is reported that absorption of arsenic by plant is influenced by the concentration of arsenic in soil7. In arsenic affected areas of West Bengal-India and Bangladesh huge quantity of arsenic is falling on agricultural land and thus it will be interesting and very important to know whether there is an increase concentration of arsenic in vegetable and crops that grow in this region. In this paper, I will report (a) the total arsenic concentration in soil, paddy (shoot, rice and husk), vegetable (including edible root, stem, leaf, and fruit) in 10 plots of land irrigated with arsenic contaminated water, (b) arsenic species in paddy (rice + husk), rice, husk, and in vegetable (also in edible root, stem, and fruit), (c) some metals and metalloids in soil, vegetable, rice. and husk, and (d) Arsenic body burden. METHODS AND MATERIALS Selection of study area Demography of the State West Bengal is 18 administrative districts and North 24- Parganas is one of the districts. North 24-Parganas is one of the 9 arsenic affected districts of West Bengal-India also. In North 24-Parganas there are 22 blocks/ police stations. Each block has several Gram Panchayets (G.P.) and in each G.P., there are several villages. We have chosen Deganga block of North 24- Parganas district as our study area. The reasons are, (A) we have the detail 8785 hand tube-wells water analysis report of Deganga one of the 22 blocks of North 24-Parganas (Table 1) and also 597 irrigation tube wells report out of 3200 which were used for irrigation in Deganga block alone (Table 2), (B) Deganga block is close (about 60 km) from our institute (SOES) with good road connection, and (C) we are working in this block for a long time and have good report with the villagers. Figure 1 shows arsenic affected block of North 24-Parganas and Deganga block. Deganga block has 13-gram panchayets and groundwater of all these gram pahchayets are arsenic contaminated (>50 µg/L). Out of 13-gram panchayets (G. P.), in 11 G. Ps we have identified patients with arsenical skin lesions. We had chosen 10 fields in Kolsur (North) village of Deganga block under Kolsur gram panchayet. Table 3 shows the crops from 10 fields we had analyzed and other related information. For control study, we had chosen the district Medinipur, an area was groundwater arsenic concentration <3 µg/L; soils of the control area show arsenic in the range 5.31 µg/gm to 6.60 µg/gm (n=6). Overall information of control area is given in Table 4. Table 1: Distribution of arsenic in tube wells water in Deganga, North 24-Parganas, West Bengal, India Table 2: Distribution of arsenic in irrigated tube wells water in Deganga block, North 24-Parganas, West Bengal-India Table 3: Type of crops and other information of 10 selected agricultural fields in Kolsur village of Deganga block, West Bengal, India where arsenic contaminated ground water was used for irrigation purpose. Table 4: Overall information of control area, where groundwater contains arsenic below 3 µg/L 21 months study report Studies had been carried for 21 months (August 1998 to April 2000). Table 5 shows the number of samples and time schedule of the whole study. Table 5: The number of samples and time schedule of the whole study (from August 1998 to April 2000) * Instrumental Techniques The FI-HG-AAS was used in School of Environmental Studies (SOES), Jadavpur University, Kolkata, India A flow injection-hydride generation - atomic absorption spectrometry (FI-HG-AAS) technique was used in our laboratory for analysis of total arsenic in water, soil, crop, and vegetable samples. The FI-HGAAS system was assembled from commercially available instruments and accessories in our laboratory. A Perkin-Elmer Model 3100 spectrometer equipped with a Hewlett-Packard Vectra computer with GEM software, Perkin-Elmer EDL System-2, arsenic lamp (lamp current 400 mA), and Varian AAS Model Spectra AA-20 with hollow-cathode As lamp (lamp current 10 mA) were used. The flow injection assembly consists of an injector, Teflon T-piece, tigon tubing and other parts for the FI system from Omni-fit UK. The peristaltic pump (VGA-76) from Varian and Minipuls-3, Gilson, Model M 312 (France) were incorporated into the FI system. Details of the instrumentation have been discussed in our earlier publications3,4. A Heraeus muffle furnace fitted with manual temperature control was used for dry ashing. The ICP-MS was used in National Institute of Health Sciences (NIHS), Tokyo, Japan A microwave digestion system (MDS-2100) from CEM Innovators in Microwave Technology, USA with a rotor for twelve Teflon digestion vessels HP-500, was used for sample digestion using HNO3 and H2O2. The ICP-MS was used from Department of Environmental Chemistry, National Institute of Health Sciences, Tokyo, Japan. Estimation of arsenic and other metals and metalloids in soil, vegetable, and paddy, (rice & husk) have been carried out by ICP-MS method. Analytical results of SRM digested similarly and analyzed by ICP-MS. The instrumental conditions of this system are shown in Table 6. Table 6: Instrumental conditions for ICP-MS The IC-ICP-MS was used from Department of U.S. Food & Drug Administration, Forensic Chemistry Center, Cincinnati, USA. The IC-ICP-MS was used from Department of U.S. Food and Drug Administration (FDA), Forensic Chemistry Center, Cincinnati, USA. The chromatographic system used consisted of a model GP 50 ion chromatography pump (Dionex, Sunnyvale, CA, USA), AS 3500 autosampler (Thermo Separations Products, San Jose, CA, USA) and a non-metallic automated switching valve (Waters, Milford, MA, USA) with 20 µL injection loop between the Column outlet and ICP-MS nebulizer. Operation of the valve was controlled using signal relays from the IC pump. A model PQ3 ICP-MS (VG Elemental) operating under normal multi-element tuning condition was used for chromatographic detection. Column effluent was directed to the concentric nebulizer and cooled conical spray chamber of the ICP-MS using a length (~60 em) of 0.25 mm. i.d. PEEK® tubing. An anion exchange column, Hamilton PRP-X 100 (4.6 x 150 mm), was used for separation of arsenic species. Chemicals and Reagents School of Environmental Studies, Jadavpur University, West Bengal, India All reagents were of analytical grade. Distilled demonized water was used throughout. Standard arsenic solutions were prepared by dissolving appropriate amounts of As2O3 (Merck, Germany) and standard arsenic (V) Titrisol (Merck, Germany). Standard stock solutions were stored in glass bottles and kept refrigerated. Dilute arsenic solutions for analysis were prepared daily. The reducing solution was sodium tetrahydroborate (Merck, Germany) 1.5% (m/v) in 0.5% (m/v) sodium hydroxide (E. Merck, India Limited). The HCl (E. Merck, India Limited) concentration was 5M. Ashing acid suspension was prepared by stirring 10% (w/v) Mg(NO3)2. 6H2O and 1% (w/v) MgO in water until homogeneous4. Standard reference materials were used to check the accuracy of the method. Pond Sediment NIES- 2, from the National Institute for Environmental Studies, Japan; Standard Chinese River Sediment 81-101 (of 1981); San Joaquin Soil SRM 2709, Citrus Leaves SRM 1572, Rice Flour SRM 1568a, Spinach Leaves SRM 1570a and Tomato Leaves SRM 1573a are from the National Institute of Standards and Technology (NIST), USA. In National Institute of Health Sciences, Tokyo, Japan All reagents were of analytical reagent grade. Milli-Q Water (Yamato Millipore filter, WT 100) was used throughout. Stock solutions (10 mg/L in water) of arsenic and other elements (Se, Cu, Zn, Pb, Mn, Ni, Hg) were prepared separately from 1000 mg/L stock standard (Cica-Merck, Kanta Chemical Co. Inc, Japan) of each element. All stock solutions were stored in polyethylene bottles and kept at 4°C. Dilute solutions (2.5, 5, 10, 20, 30, and 50 µg/L) for analysis were prepared daily. The samples digestion was carried out with concentrated nitric acid (HNO3) (Wako Pure Chemical Industries Ltd., Osaka, Japan) and high purity hydrogen peroxide (H2O2) (Wako Pure Chemical Industries Ltd., Osaka, Japan). Standard reference materials were used to check the accuracy of the method for multi element analysis. Rice flour SRM 1568a, Apple leaves SRM 1515, Tomato Leaves SRM 1573a, San Joaquin Soil SRM 2709, and Spinach leaves SRM 1570a are from the National Institute of Standards and Technology (NIST), USA. In U.S. Food and Drug Administration, Cincinnati, U.S.A. Ultrapure deionized water was used (DIW, Millipore, MA, USA). High-purity ammonium hydroxide was from Fisher Scientific (Fair Lawn, NJ, USA). Anhydrous trifluoroacetic acid (TFA) was from Sigma (St. Louis, MO, USA), and ammonium nitrate, and monobasic ammonium phosphate were from J.T. Baker (Phillipsburg, NJ, USA). Commercial stock standards of As(III) and As(V) (1000 µg As/mL as As2O3 in 2% HCl and H3AsO4. ½ H2O in 2% HNO3, respectively) were obtained from Spex Industries (Metuchen, NJ, USA). Dimethylarsinic acid (98.0%) and disodium methyl arsenate (99%) were obtained from Chem Service (West Chester, PA, USA). The mobile phase consisted of 10 mM NH4H2PO4 and 10 mM NH4PO3 adjusted to a pH of 6.3 with NH4OH. NIST SRM 1568a rice flour was used for method validation Sample collection and preservation Water samples Tube well water samples were collected in pre-washed (with 1:1 HNO3) polyethylene bottles. After collection concentrated nitric acid (1.0 ml per liter) was added as preservative. Samples, which were not analyzed immediately, were kept in a refrigerator at 4°C. Details of the collection procedure have been described in our earlier publications3,4. Vegetable and crop samples Vegetable and crop samples were collected from selected agricultural fields where arsenic contaminated water was used for agricultural purposes. Vegetable, crop, and plant samples were picked by hand, stored in polyethylene bags, and kept cool until processing in the lab. Samples were washed thoroughly with tap water to remove soil and other particles, and finally washed in sonicator with demonized water for several times. Prior to sample washing, plants consisting of both roots (below soil surface) and shoots (above soil surface) were separated into root, stem, leaf, and fruit as a sub samples and dry matter yields after drying at 60°C for about 72 hours. Dry samples made fine powder by Agate pestle and mortar, sieved, and stored in polyethylene bags with proper leveling at room temperature. Soil samples Surface soil samples and samples at different depth were collected from agricultural fields, where arsenic contaminated water was used for agricultural purposes and samples were also collected from non-arsenic contaminated agricultural fields (arsenic concentration in agricultural water was <3 µg/L). We collected four soil samples from different part of the same field and made a mixture. Samples were picked by non-metallic spoon, stored in polyethylene bags, and kept cool until processing in the lab. First soil samples were dried at room temperature and finally at 60°C for several hours. Dried samples were made fine powder by Agate pestle and mortar, sieved, and stored in polyethylene bags with proper leveling at room temperature. Sample treatment for analysis In SOES Laboratory Sand bath digestion of soil samples Approximately 0.10 to 0.50 gm of soil sample was placed in a 25cc conical flask (glass), 2 mL deionized water added, followed by 2 mL concentrated HNO3 and 1 mL concentrated H2SO4 (Analar Grade, E. Merck, India). The mouth of the flask was covered with a small glass funnel. Then it was heated on a sand bath until the fumes of SO3 evolved. When fumes of SO3 evolved, heating was discontinued and after cooling, the solution was diluted and filtered through a millipore membrane (0.45µm pore size) filtering apparatus, then adjusted to fixed volume. Standard Reference Materials (SRM) was analyzed in the same way to test the accuracy. Dry ashing digestion of vegetable and crop samples Approximately 0.20 to 0.70 gm of dry vegetable/ crop sample or 1.5 gm to 3.0 gm of wet/weight vegetable sample was taken into a 100 ml Borosil Conical Flask and 10 ml ashing aid [10% (w/v) Mg(NO3)2. 6H2O (Riedel-De Haenag, Seelze- Hannover, Germany) + 1% (w/v) MgO (E. Merck, Darmstadt, Germany) in deionized water] was added with continuous agitation. Then 5 mL HNO3 (40%, v/v) was added and evaporated to almost dryness on a hot plate at about 90-100°C. When the sample dried, the beakers were covered with a pre-washed watch glass and transferred to the muffle furnace2. The following temperature program was adopted for proper ashing of the sample: 150°C for l hr, 200°C for 30 min, 250°C for 30 min, 300°C for 2 hrs, 400°C for l hr, and 450°C for 12-14 hrs. After cooling to room temperature 2 mL (10% v/v) HNO3 was added to the carbonaceous residue. The mixture was dried again on the hot plate to dryness and transferred to the furnace. The ash was subjected again to the following temperature program: 150°C for 1 hr and 30 min, 300°C for 30 min, and 450°C for 12- 14hrs. After cooling the white ash was moistened with a few drops of water, dissolved in 1-2 mL 6M HCI and filtered through a Millipore filter (0.45 µm) and finally made the proper volume with 6M HCl. Triplicate blanks and Standard Reference Materials (SRM) were-prepared following the same digestion procedure. Microwave digestion of soil, vegetable, and crop samples in NIHS, Tokyo, Japan Samples for digestion were weighed (0.2 gm to 0.5 gm of dry sample) in the Teflon vessel and added 2:1 v/v of nitric acid and hydrogen peroxide. The vessels were closed using the lid provided. For safety of the vessel, rupture membrane was inserted in the lid. Vessels were set in the turn table of the micro-wave digestion machine and the below settings were programmed (Table 7). Table 7: Optimum parameters for sample digestion by microwave system After cooling for 30 minutes, the vessels were opened carefully. Each digested solution was transferred quantitatively to a 10 mL volumetric flask and adjust to fixed volume with Milli-Q water. Finally, it was filtered through a Millipore membrane (0.45 µm) (CASL 45 2.5 CMD, membrane: Acetyl Cellulose) and kept in plastic container for analysis. The Standard Reference Materials (SRM) were digested under the same digestion procedure. Preparation and extraction of crop and vegetable samples for arsenic speciation (FDA lab, USA) The rice and vegetable samples were grounded in an acid-washed glass mortar and pestle. A larger amount of each of the paddy sample was shipped; therefore, they were milled and sieved (0.5 mm) in a model ZM 100 ultra-centrifugal mill (Retsch, Haan Germany). Prepared samples were stored in HDPE bottles at ambient temperature prior to use. Sample (0.1-0.5gm) were mixed with 0.5-2 mL of 2M trifluoroacetic acid (TFA) and allowed to stand for 6 hours at 100°C in either a 15 mL or a 60 mL capped HDPE centrifuge tube. The TFA extract was allowed to cool and diluted to volume (10-25 mL) with Ultrapure deionized water (DIW, Millipore, MA USA). Extracts were filtered through a 0.45 µm Nylon syringe filter prior to analysis by IC-ICP-MS. Sample analysis Flow injection-hydride generation-atomic absorption spectrometry (Fl-HG-AAS) (SOES Lab.) The sample was injected into a carrier stream of 5M HCl by means of a six-port sample injection valve fitted with a 50 µL sample loop. The injected sample, together with carrier solution met subsequently with a continuous stream of sodium tetrahydroborate. Mixing with sodium tetrahydroborate generated hydride, which subsequently entered the ice water bath and then the gas-liquid separator apparatus, which was cooled with ice-cold water. This cooling procedure and the design of the gas-liquid separator are more efficient than conventional FI-AAS and the possibility of water vapor entering the quartz cell is reduced to a great extent. Inside this apparatus a continuous flow of N2 carrier gas assists mixing and the reaction and subsequently carries hydride to the quartz tube mounted in the air-acetylene flame for As measurement. Peak signals were recorded using a computer linked to the atomic absorption spectrophotometer (AAS) that is capable of both peak height and peak area measurement. The peak height signals were measured and the concentrations of arsenic of the samples were measured/calculated against the standard curve. The experimental condition for FI-HG-AAS system is given in the Table 8. Table 8: Optimum-Parameters for arsenic determination by flow infection (FI) system Water Samples Preserved water samples (in 1 mL HNO3 per liter of water) were analyzed by FI-HG-AAS against arsenite and arsenate mixture (1:1) as the standard. Soil, vegetable, and crop samples Digested samples were analyzed by Fl-HG-AAS method against arsenate as the standard. Inductively Coupled Plasma-Mass Spectrophotometry (ICP-MS) (NIHS Lab., Japan) ICP-MS Analysis ICP-MS is an element selective detector. Twenty microliters (20 µL) of the microwave acid digested sample were injected into a carrier stream of Milli-Q water with a sample loop. The Chromatographic areas were measured, and the concentrations of elements were calculated against the individual element standard curve. The experimental conditions of ICP-MS are given in Table 6. Ion chromatography-inductively coupled plasma-Mass spectrophotometry (IC-ICP-MS) (Food & Drug Lab., USA) Figure 7 shows the chromatogram obtained for a standard mixture of As(III), DMA, MMA and As(V) in our experimental condition (Table 9). Each of the arsenic species is present at an arsenic concentration of 2 ng/mL. Data was collected for 10 minutes. The four arsenic species are baseline resolved in under 8.5 minutes; however, arsenobetaine (AsB) is not resolved from As(III) under these separation conditions. AsB is generally found in fish and shellfish samples and is not expected to be present in vegetable or rice samples collected from arsenic contaminated agricultural fields. The precision of peak areas measured over a period of 4 hours (n=5) using replicate 25 µL injections of a standard containing 2 ng/mL each of As(III), DMA, MMA and As(V) was 4.8%, 4.4%, 4.1%, and 9.0%, respectively. As estimate of the instrumental detection limit (IDL) for each of the arsenic species was calculated based on 3 times, the standard deviation of peak area measurements for replicate 25 µl injections of a standard containing 0.2 ng As/mL each of As(III), DMA, MMA and As(V). The IDLs were 0.1, 0.1, 0.1 and 0.2 ng/mL for As(III), DMA, MMA and As(V), respectively. Table 9. IC-ICP-MS operational condition Samples were analyzed using calibration standards at 0.5, 1, 2, 5 and 10 ng/mL concentrations (in some cases a 20 ng/mL standard was also used). Peak areas were corrected for any drift associated with the flow injection signal at the beginning of each chromatogram. The concentrations of several samples were also checked using standard addition. Spikes of each of the arsenic species were taken through the method and spike recoveries of 83%, 88%, 100%, and 93% were obtained for As(III), As(V), MMA and DMA, respectively. However. it should be noted that As(V) can be partially reduced during the extraction procedure. The As(V) recovery was calculated in spiked samples using the sum of the increase in the As(III) and As(V) concentrations. Because of this partial reduction, the method is only capable of providing total inorganic arsenic as the sum of the As(III) and As(V) concentrations. Standard NIST SRM 1568a Rice Flour also analyzed by the same procedure and the sum of the arsenic species concentrations for SRM Rice Flour (0.27 µg/gm) compared well with the certified total arsenic value (0.29 µg/gm). Total arsenic in irrigation tube wells, soil, vegetable, paddy samples were analyzed by using FI-HG-AAS after dry ashing (vegetable, rice, and husk) and acid digestion (soil) Water samples used for cultivation had been collected from 10 locations and analyzed by FI-HG AAS method and their results are given in Table 10. Similarly, soil samples had Table 10: Analysis of arsenic and iron for 10 irrigation tube-well used in 10 fields for cultivation Table 11: Analysis of arsenic in soil where arsenic contaminated groundwater was used for cultivation Table 12: Distribution of arsenic concentration in different parts of the vegetable collected from 6 fields out of 10 irrigated with arsenic contaminated water Table 13: Distribution of arsenic concentration in different parts of paddy plant collected from 3 selected location of Kolsur (N) in Deganga block, North 24-Parganas, West Bengal, India during monsoon period and rainwater was used for cultivation Table 14: Distribution of arsenic concentration in different parts of paddy plant collected from 5 selected fields of Kolsur (N) village in Deganga block, North 24-Parganas, West Bengal, India during pre-monsoon period and cultivated with arsenic contaminated groundwater Table 15: Analytical results of Standard Reference Matarial (SRM) by FI-HG-AAS Arsenic concentration in irrigation tube well and soil before and after a devastating flood During September 2000 to October 2000 of our 10 experimental Fields were submerged with water due to a devastating flood. The analytical results are given in Table 16. Table 16: Arsenic concentration in irrigation tube well and soil before and after a devastating flood been collected from 10 fields where contaminated underground water was used for cultivation. The analytical results of those soil samples are given in Table 11. Vegetable and paddy samples (including various parts) cultivated with arsenic contaminated water had been collected time to time from selected fields. Their analytical results are given in Table 12, 13, & 14, respectively. Analytical results of Standard Reference Material (SRM) digested similarly & analyzed by FI-HG-AAS given in Table 15. Total arsenic and other metals and metalloids in soil, vegetables, and paddy (rice & husk) samples by using ICP-MS after microwave digestion. Estimation of arsenic and other metals and metalloids in soil, vegetable, and paddy, (rice & husk) have been carried out by ICP-MS method. Total arsenic and other metals and metalloids concentrations in soil, rice (also in husk), and vegetable are given in Table 17, 18, and 19, respectively. Analytical results of SRM digested similarly and analyzed by ICP-MS given in Table 20. Table 17: Concentration (µg/gm) of 7 elements in 9 contaminated soils collected from arsenic contaminated fields of West Bengal- India and Bangladesh Field No. As in water (µg rl) Type of sample As Mn Cu Hg Pb Ni Zn Fl 805 Soil 34.15 732.9 58..44 1.13 67.36 72.29 80.38 F2 570 Soil 43.08 508.20 49.07 1.13 52.87 53.76 105.00 F3 156 Soil 17.46 388.33 38.25 1.36 39.67 40.48 58.53 F4 488 Soil 34.11 538.68 54.65 1.20 52.38 53.71 70.08 F6 215 Soil 25.63 514.93 49.16 1.26 57.12 61.44 68.54 F7 218 Soil 25.54 457.46 46.34 1.47 40.33 51.12 45.62 Fl0 195 Soil 23.41 415.47 42.60 1.61 43.87 44.59 52.12 Bangladesh 492 Soil ':I 40.98 484.29 51.05 1.15 46.89 50.08 - Bangladesh 525 Soil ' 42.13 473.62 49.20 0.96 55.92 61.67 71.47 Table 18: Concentration (µg/gm) of 7 elements in rice and husk collected from arsenic contaminated agricultural fields of West Bengal-India and Bangladesh BDL: Below Detection Limit Table 19: Concentration (µg/gm) of 7 elements in vegetable samples collected from arsenic contaminated agricultural fields of Bangladesh * A kind of vegetable, whole portion (stem + leaf) is used for food and local name 'Data' ** A kind of popular vegetable, whole portion (root +stem+ leaf) is used for food and local name 'Kachu'. Table 20: Analytical results of NIST Standard Reference Material (SRM) by ICP-MS Arsenic species in paddy (rice+ husk), rice, husk, and vegetable by IC-ICP-MS after TFA (trifluoroacetic acid) extraction The analytical results are given in Tables 21 and 22. Table 21: Concentration of arsenic species (ng/gm) and percentage of inorganic arsenic and methylated arsenic in rice, husk, paddy (rice+ husk) & vegetable (dry) collected from arsenic contaminated fields in Kolsur (N) village of Deganga block, North 24-Parganas, West Bengal, India Table 22: Concentration of arsenic species (ng/gm) and percentage of inorg-As and methylated arsenic in paddy (rice+ husk) and vegetable (dry) collected from arsenic contaminated fields in Datterhat village of Madaripur district, Bangladesh Results & Discussion Table 10 shows analysis of arsenic from August 1998 to April 2000 of 10 tube wells used in 10 fields for irrigation purpose. Although from the results of arsenic in tube wells it appears that in some of the tube wells there is increase of arsenic with time but this type of variation, we had experienced in many tube wells during our work in West Bengal-India and Bangladesh. It has also been observed that arsenic concentration in same field varies locations to location (Table 23) and concentration of arsenic is higher at the surface than at any depth (Table 24 and Figure 2). Table 24 and Figure 2 indicate that arsenic concentration is higher at surface and at depth 18-inch and 36-inch the variation is minimum. Table 23. Distribution of arsenic concentration (µg/gm) of soil samples collected from different location of the same arsenic contaminated fields during August 1998. Table 24. Distribution of arsenic concentration (µg/ gm) in contaminated soil with depth Figure 2: Distribution of arsenic concentration (µg/ gm) in soil with increasing depth (in inch.). Table 16 shows arsenic concentration in irrigation tube wells and soil measured in April 2000 and again in April 2001 after flood. Our 21 months study on arsenic in soil, crop, and vegetable finished during April 2000. However, during September 2000 - October 2000 there was a devastating flood in West Bengal. Most of the parts of North 24-Parganas including our 10 experimental fields were submerged in floodwater. During April 2001 we went to the fields and collected water and soil samples from the same location of our experimental fields. Table 16 indicates that there is almost no change of arsenic in irrigation tube well, but drastic change of arsenic in soil. Thus, it appears that arsenic from soil after flood washed away but six months was not sufficient for aquifer dilution. Table 25 shows arsenic concentration in rice & husk (a) cultivated with arsenic contaminated underground water & elevated arsenic concentration in soil, (b) cultivated with rainwater & arsenic concentration in soil is low, and (c) controlled cultivation: cultivated by ground water having arsenic <3 µg/L and soil arsenic concentration 5.31-6.13 µg/gm. From the Table 25 it appears that higher the arsenic concentration in irrigation water & soil, higher is the arsenic concentration in rice & husk. In pre-monsoon cultivation paddy was grown in arsenic rich irrigated water with elevated arsenic in soil. But in monsoon cultivation, contribution of arsenic from water for irrigation was not there. So, also arsenic in soil has gone down as rainwater washed away some arsenic from soil. It shows that the average arsenic concentration in contaminated soil, rice, and vegetable were 3.81, 3.62, and 5.66 times higher than the control samples, respectively. Estimation of arsenic in different parts of the vegetable & paddy had also been carried out to know the distribution of arsenic in stem, leaf, and fruit for vegetable and shoot, rice, & husk for paddy. Analytical results of few are represented in Tables 12-14. Table 13 is the arsenic concentration in paddy irrigated with rainwater (monsoon) and Table 14 is for paddy irrigated with arsenic contaminated groundwater (pre-monsoon). The overall observations from Tables 12-14 are arsenic concentration in vegetable and paddy increases when arsenic in soil is higher and when cultivated with arsenic contaminated groundwater. Also, for paddy arsenic concentration decreases shoot > seed (rice) > husk and in vegetables the distribution is leaf> stem > fruit. Although it is reported8 that root contains maximum amount of arsenic, but we could not analyze root for paddy plant as we were not sure about adhered soil remove from root. Arsenic in different parts of paddy with increasing concentration of arsenic in soil is given in Figures 3 (pre-monsoon and higher concentration of arsenic in soil) & Figure 4 (monsoon and arsenic concentration in soil is low) and that of vegetable given in Figure 5. Figure 3: Distribution of arsenic in different parts of paddy (pre-monsoon) with increasing arsenic concentration in soil. Figure 4: Distribution of arsenic concentration in different parts of paddy (monsoon) with increasing arsenic concentration in soil. Figure 5: Distribution of arsenic concentration in different parts of vegetable with increasing arsenic concentration in soil. Arsenic analysis of few rice and vegetable samples were done from different laboratories. Results are given in Tables 26-28. FI-HG-AAS after Teflon bomb digestion was done from our laboratory; microwave digestion followed by ICP-MS was done from National Institute of Health Sciences (NIHS) laboratory, Tokyo, Japan & IC-ICP-MS for various species done from US Food and Drug Administration Laboratory, Forensic Chemistry Center, Cincinnati, USA. Results of IC-ICP-MS represents only sum of inorganic arsenic (In-As) + MMA + DMA. It is expected IC ICP-MS results will be low compared to FI-HG-AAS & ICP-MS results after digestion. Table 26: Arsenic concentration in same rice and paddy (rice+ husk) samples measured by using FI-HG-AAS and IC-ICP-MS in different laboratories. Table 27: Arsenic concentration in same rice and paddy (rice+ husk) samples (contaminated) measured by using FI-HG-AAS and IC-ICP-MS in different laboratories. Table 28: Arsenic concentration in same vegetables samples measured by using FI-HG-AAS, ICP-MS, and IC-ICP-MS in different laboratories. Total arsenic and other metal and metalloid in soil, vegetable, and paddy in some samples of West Bengal-India and Bangladesh Along with arsenic in soil samples (n = 9), Mn, Cu, Hg, Pb, Ni & Zn were analyzed by ICP-MS after microwave digestion (Table 17). Our analysis of NIST soil sample (Table 20) by the same procedure is in well agreement. The regression analysis was carried out between arsenic and other metals. However, no significant positive or negative co-relation was observed between As & Mn (r=0.382, p=0.309), As & Cu (r=0.632, p=0.067), As & Ni (r = 0.460, p= 0.212) and As & Pb (r = 0.493, p = 0.177). A significant (<0.05) positive correlation found between As & Zn (r = 0.763, p = 0.027) and also a strong negative correlation was observed between As & Hg (r = -0.802, p = 0.009). Table 18 shows analysis of As along with Se, Mn, Cu, Hg, Pb & Ni in rice & husk of 3 paddy samples cultivated with arsenic contaminated water. The regression analysis was carried out between arsenic and other metals. Linear regression shown negative correlation between As & Se (r= -0.999, p = 0.018), As & Pb (r = -0.992, p = 0.078) and positive correlation between As & Cu (r = 0.998, p = 0.03). But no satisfactory correction observed between As & Mn (r = -0.980, p =0.126), As & Hg (r = -0.452, p 0.70) and As & Ni (r = -0.233, p = 0.849). It has been observed selenium concentration decreases with increase arsenic concentration in both rice and husk (Table 18 & Figure 6). This has also been observed in two vegetable samples those we had studied (Table 19). All analyzed elements concentration (µg/gm) were less in “Kachu” comparing “Data” except arsenic. Arsenic was very high in “Kachu” comparing “Data” even though they were irrigated with same water containing arsenic 205 µg/L. Figure 6: Co-relation between arsenic and selenium in rice cultivated by using arsenic contaminated water. Arsenic species in vegetable, rice, and paddy in some samples of West Bengal, India and Bangladesh Table 21 & 22 show total arsenic in groundwater used for irrigation and arsenic in soil. The sum of arsenic species in vegetable, paddy (rice + husk), rice, husk, and arsenic species in those samples from West Bengal-India & Bangladesh also shown in these table respectively. In Table As(III) and As(V) presented together as inorganic arsenic. The reason show portion of As(V) is reduced to As(III) during extraction. Figure 7 shows the chromatogram of As(III), MMA, DMA and As(V) measured by IC-ICP MS. Figure 8 shows arsenic species in rice (Sample no. 1 in Table 21). It appears from all four-rice analysis that inorganic arsenic is the major portion of arsenic in rice. Figure 9 shows arsenic species in husk (Sample no.6 in Table 21). All four-husk analysis shows only presence of inorganic arsenic. No methylated form of arsenic was found in any husk samples. Figure 10 shows arsenic species present in lady's Finger (Sample no.18 in Table 21). It shows presence of inorganic arsenic & DMA, and possibility of an unknown arsenic species. Figure 11 shows arsenic species in a paddy (rice+ husk) sample (Sample no.11 in Table 21). It has high inorganic arsenic (76.46%) and 19.37% DMA & 4.23% MMA. Figure 12: Sample No. 5B in Table 22; Peak identities: 1, As(III); 2, DMA; 4, As(V) and an unknown peak Figure 12 shows very high arsenic concentration in a vegetable named “kachu” (Sample no.5B in Table 22) which grows inside soil a popular food in West Bengal-India & Bangladesh. Most interesting, its arsenic concentration in very quite high but it has no detectable amount of methylated form of arsenic and possible of an unknown arsenic species. The overall conclusion from arsenic analysis in rice, paddy (rice + husk) and some vegetables are that inorganic arsenic is the dominating species of arsenic. Conclusion Food habit and arsenic intake from food and water to those living in arsenic contaminated villages. Rice and vegetable are the staple food for poor villagers of West Bengal-India and Bangladesh. This is true for the villagers in Kolsur gram-panchayet (G.P.) in Deganga block of North 24-Parganas district, West Bengal-India, where we studied for 21 months arsenic in soil, rice, and vegetable from 10 plots cultivated with arsenic contaminated water. Normally, 3 times villagers eat rice with mainly vegetable per day. Adults (male or female) normally eat 250 gm of rice every time i.e., 750 gm of rice per day and child (around 10 years) eat 400 gm of rice during whole day. Adults eat in average 165 gm of cooked vegetable to each meal and child around 100 gm. Average water intake per day for adult male, adult female, and child are 4 liters, 3 liters, and 2 liters, respectively. Those who work in field consume more water (average 6.0 liters) and during summer the average water intake to those work in field may go as high as 10 liters. Villagers are also consuming arsenic from Pantavat# and water added for food preparation like rice, soup, curry, and drinks like tea, lemon water, etc. After thorough discussion with the villagers, it appears that this is equivalent to consumption of 1 liter of water for adult and 500 ml for child. Normal daily average food intake for adult to each meal is as follows: #PANTAVAT: This is common food for villagers of W. Bengal-India and Bangladesh at breakfast. Pantavat is rice mixed with water. Normally they pour water to the rice cooked on the previous night and have it as their breakfast. Normally, villagers eat Pantavat with vegetable/ smashed Potato/ Chili and Onion. Total arsenic burden to the villagers from water and food We have classified arsenic intake in three categories: Category I Arsenic alone from contaminated drinking water. Category II Arsenic from food (rice and vegetable). Category III Arsenic from contaminated water added to 'Pantavat' and for food preparation (rice, soup, curry, drinks like tea, lemon water). Altogether, we had analyzed 571 hand tube wells from North Kolsur village and out of these 80% • tube wells contains arsenic above 10 µg/L and 70% tube wells contain above 50 µg/L. The average • arsenic concentration in contaminated hand tube wells (n=399) is 200 µg/L. When we started our work in this village, villagers were drinking arsenic contaminated water. We informed them about contamination of their hand tube-wells and identified safe tube wells for them in their village. We do not know what percentage of villagers consuming safe water are, but we know for irrigation purpose they are still using contaminated tube well water. Arsenic concentration in hand tube well they were drinking is given in Table 29. We had collected and analyzed soil, rice, vegetable, and water used for irrigation for our 10 studied fields in North Kolsur village. Arsenic concentration in 10 fields shown in Tables 3 & 10. Villagers close to our studied areas are consuming rice and vegetable from these 10 fields. Average arsenic concentration in soil (n=68), rice (n=8) and vegetable (n=30) are 22.30 µg/gm (range 7.91µg/gm to 43.08 µg/gm, dry weight), 0.358 µg/gm (range 0.120 µg/gm to 0.663 µg/gm, dry weight) & 0.034 µg/gm (range 0.008 µg/gm to 0.120 µg/gm, wet/weight), respectively. Our preliminary study indicates that edible portion that vegetable grow inside soil contain high amount of arsenic. Villagers were also using the contaminated hand tube well's water for PANTAVAT (average 200 ) µg As/L). Control soil (n=6), rice (n=3), and vegetable (n=3) samples contain arsenic (average) 5.84 µg/gm (range 5.31 to 6.60 µg/gm), 0.089 µg/gm (range 0.083 to 0.959 µg/gm), and 0.009 µg/gm (range 0.007 to 0.012 µg/gm), respectively. Our preliminary study indicates, we have arsenic concentration in irrigated water of control area is <3 µg/L. Our control area was Medinipur district, which is not arsenic contaminated. It appears that the average arsenic concentration in contaminated soil, rice, and vegetable are 3.81, 3.62, and 5.66 times higher than the control samples, respectively. Table 30 to Table 32 show arsenic burden to each villager from contaminated tube well water alone, from rice, vegetable, and from water added for Pantavat and food preparation, respectively. Table 29: Distribution of arsenic in hand tube well water samples of North Kolsur village in Deganga block of North 24-Parganas district, West Bengal-India North Kolsur villagers body burden of total arsenic, inorganic arsenic, and organic arsenic from water, food, and water added for food preparation Our earlier study9 shows that arsenic compounds present in hand tube well from our study area are arsenite and arsenate. Our present rice and vegetable analysis show [preliminary study on total inorganic and organic arsenic compounds in some rice and vegetable samples measured by using IC-ICP-MS10 from US Food and Drug Administration, Forensic Chemistry Centre, Cincinnati, USA] 95% and 5% are inorganic arsenic and organic arsenic in rice, and 96% and 4% of inorganic arsenic and organic arsenic in vegetable. Table 30: Arsenic burden to each adult male, adult female, and child from water alone at North Kolsur village of Deganga block of North 24-Parganas, West Bengal-India Table 31: Arsenic burden to each adult male, adult female, and child from contaminated rice and vegetable per day Table 32: Arsenic burden to each adult male, adult female and child from contaminated water added for pantavat and food preparation per day Table 33 shows arsenic burden (total, inorganic arsenic, and organic arsenic) to each adult male, adult female, and child combining category I, II and III. Table 34: Arsenic from food to North Kolsur villager and from other countries Table 34 shows a comparative study of inorganic arsenic and total arsenic intake of North Kolsur villagers along with some other countries3. The high concentration of arsenic to population in Japan, Spain, Manaus region of Brazil is due to high intake of seafood. It is also obvious that organic arsenic contributions from other countries represented in Table 34 are also substantial from seafood. North Kolsur villagers rarely consume seafood. From the results of total arsenic (drinking water + rice + vegetable + Pantavat + water added for food preparation) body burden to North Kolsur villagers (1185.0 µg for per adult per day, 653.2 µg for per child per day), amount of arsenic coming from rice, vegetable, and water added for Pantavat and food preparation is 485 µg i.e., 41% of total for adult and 253.2 µg i.e., 38.8% for child and from rice and vegetable 285 µg i.e., 24% of total for adult and 153.2 µg i.e., 23.4% for child (around age l0 years). Our findings show most of the arsenic coming from food is inorganic in nature. As toxicity of most of the organic arsenic compounds in food is less compared to inorganic arsenic, North Kolsur people appears also at risk from arsenic in food. According to WHO11, 1.0 mg of inorganic arsenic per day may give rise to skin effects within a few years. It has been estimated that based upon the current U.S. Environmental Protection Agency (EPA) standard of 50µg/L, the lifetime risk of dying from cancer of the liver, lung, kidney, or bladder, from drinking 1 liter per day of water could be as high as 13 per 1000 persons12. Using the same methods, the risk estimate for 500 µg/1 of arsenic in drinking water would be 13 per 100 persons13. In its latest document on arsenic in drinking water, the U.S. National Research Council (NRC) concluded that exposure to 50 µg/1 could easily result in a combined cancer risk14 of 1 in 100. Comparing to the WHO, EPA, and NRC document with arsenic burden to Kolsur villagers from water and food it appears that Kolsur villagers’ risk of suffering from arsenical skin effect and cancer is there. Compared to worldwide arsenic consumption from food, it appears Kolsur villagers are also consuming high amount of inorganic arsenic from food and vegetable. Kolsur village is an example of many such villages in West Bengal-India and Bangladesh. Further, products from arsenic irrigated water- soil system rich in arsenic are also coming to common marketplace far away from contaminated areas and even people who are not drinking arsenic contaminated water may get arsenic from food products produced from contaminated fields. In West Bengal-India and Bangladesh rice, vegetable, and other products are coming to cities (including Kolkata in West Bengal-India and Dhaka in Bangladesh) from villages and possibility that city people consuming arsenic contaminated products from contaminated areas cannot be ruled out. In one of our studies2 we mentioned that arsenic in urine (metabolites) to a group of controlled population using water for drinking and cooking having arsenic <3 µg/L, have arsenic in their urine higher than normal level. This explains that a high background level of arsenic is resulted to the surroundings of arsenic contaminated area due to arsenic coming from food chain. Acknowledgement: The Author wants to dedicate this paper to the memory of Prof. Dipankar Chakarborti who passed away on February 28, 2018. He was the founder and Director of the School of Environmental Studies (SOES), and Professor in the Department of Chemistry at the Jadavpur University, Kolkata, India. Dr. Chakarborti was my Ph.D. supervisor, and this research work was done under his sole supervision with great contributions. I would like to thank to the Chairman of the Jawaharlal Nehru Memorial Fund, Teen Murti House, New Delhi, India for the financial assistance throughout my research work. I gratefully acknowledge Dr. Masanori Ando, Dr. Hiroshi Tokunaga, and the authorities of the National Institute of Health Sciences, Tokyo, Japan for their laboratory support and cooperation. I express my deep gratitude to Dr. Douglas T. Heitkemper, U.S. Food and Drug Administration, Forensic Chemistry Centre, USA for his help to analyze vegetable and crop samples for arsenic species. Reference Mandal, B.K., Chowdhury, T.R., Samanta, G., Basu, G.K., Chowdhury, P.P., Chanda, C.R., Lodh, D., Karan, N.K., Dhar, R.K., et al (1996). Arsenic in groundwater in seven districts of West Bengal, India - the biggest arsenic calamity in the Current Sci., 70 (2), 976-986. Mandal, B.K. (1998). Status of arsenic problem in two blocks out of sixty in eight groundwater arsenic affected districts of West Bengal - India (Ph.D. Thesis). Jadavpur University, Calcutta, Arsenic (2000).: Environmental Health Criteria. Geneva, Switzerland: World Health Organization. Chapter 5: p. 27. Weiler, R. R. (1987) Unpublished data. Ministry of the Environment Rep. 87-48-45000-057, Toronto, Ont. Data presented in reference 5. Debeka, R. W. et al (Jan Feb-1993). Survey of arsenic in total diet food composites and estimation of the dietary intake of arsenic by Canadian Adults and children. Jour. AOAC, 76:1:14. Special Report on Ingested Inorganic Arsenic. Skin Cancer; nutritional essentiality, EPN625/ 3-87/013, Washington DC (1988). National Academy of Sciences (1977): Arsenic:The National Research Council (NRC), Washington DC, p332. Jacobs,L.W., Keeney,D.R., and Walsh,L.M. (1970). Arsenic Residue Toxicity to Vegetable and Crops Grown on Plainfield Sand. Agronomy J., 62, 588-591. Chatterjee, A., Das, D., Mandal, B.K., Roy Chowdhury, T., Samanta, G., Chakraborti, D. (1995). Arsenic in groundwater in six districts of West Bengal, India: the biggest arsenic calamity in the world. Part I: Arsenic species in drinking water and urine of the affected people. The Analyst, 120, 643-650. Douglas, T.H., Nohora, P.V., Kirsten, R.S., Craig, S.W. (2001). Determination of total and speciated arsenic in rice by ion chromatograpyh and inductively coupled plasma mass spectrometry. J. Anal. At. Spectrom., 16: 299-306. Perarce, F. (1998). Arsenic in water. The Guardian (UK), 19/25 February, 2-3. Arsenic (1981): Environmental Health Criteria 18. Geneva, Switzerland: World Health Organization. Smith, A.H. et al. (1992). Cancer risks from arsenic in drinking water. Environmental Health Perspectives. 97: 259-267. Smith, A.H. et al. (1999). Cancer risks from arsenic in drinking water: Implications for drinking water standards. In: Proceedings of the Third International Conference on Arsenic Exposure and Health Effects, 12-15 July 1998, San Diego, Elsevier Science Ltd., Oxford, UK. pp 191-200.
Impact of arsenic (As) contaminated groundwater on human health, through drinking and irrigation practices, is of grave-concern worldwide. This paper present the review of various sources, processes, health effects and treatment technologies available for the removal of As from arsenic contaminated water. Groundwater with high As concentration is detrimental to human health and incidents of As contamination in groundwater had been reported from different parts of the globe. More serious known As contamination problem as well as largest population at risk are found in Bangladesh, followed by West Bengal state in India along the Indo-Gangetic plains. Large scale natural As contamination of groundwater is found in two types of environment such as strongly reducing alluvial aquifers (ex. Bangladesh, India, China and Hungary) and inland basins in arid or semi-arid areas (ex. Argentina and Mexico). The provisional guideline of 10 ppb (0.0 l mg/l) has been adopted as the drinking water standard by World Health Organization (WHO). In the aquatic environment, the release, distribution and remobilization of As depend on temperature, redox potential, speciation, and interaction between liquid solution and solid phases. As predicaments in the environment is due to its mobilization under natural geogenic conditions as well as anthropogenic activities. Arsenic mineral is not present in As contaminated alluvial aquifer but As occurs adsorbed on hydrated ferric oxide (HFO) generally coat clastic grains derived from Himalayan mountains. As is released to the groundwater mainly by bio-remediated reductive dissolution of HFO with corresponding oxidation of organic matter. The development of strongly reductive dissolution of mineral oxides (Fe and Mn) at near-neutral pH may lead to desorption and ultimately release of As into the groundwater. As release through geochemical process is more important factor in alluvial aquifers causing As contamination rather than sources of arsenic. As is a toxin that dissolves in the bloodstream, rendering the victim susceptible to disease of the skin, bones, and also cancer of liver, kidney, gall bladder and the intestines. It is necessary to adopt highly successful technology to treat As contaminated water into the acceptable limit for human consumption. Universally accepted solutions are not developed/available even after the lapse of almost forty years since slow As poisoning identification in tens of millions of people especially in Bengal delta. The issue poses scientific, technical, health and societal problems even today.
Arsenic is a toxic carcinogen mostly found in subsurface environments. It is released into groundwater mostly via natural geological and hydrological processes. Consumption of such contaminated water leads to serious health crises for mankind. Developing countries in South Asia, particularly the rural regions, have been severely affected by this environmental phenomenon. In India, government authorities have implemented several remedial measures to provide safe drinking water to the rural habitations, ranging from utilization of surface water bodies (e.g., rivers, ponds, etc.) for piped water supply schemes and establishment of groundwater treatment units. This article attempts to review the scientific literature describing the critical situation in India's fourth most populous state of West Bengal and the engineering advances made in the mitigation. The issue of safe disposal or stabilization of arsenic wastewaters generated from the treatment units is often not emphasized in policy discussions. In a concluding note, this article proposes innovations necessary for achieving effective arsenic mitigation in the region that involve both groundwater remediation and waste management in tandem for sustainability.
Groundwater is known as the least contaminated source of freshwater on Earth. It is being excessively used in different sectors for diverse purposes such as drinking, agriculture, industrial use, and fish culture. Approximately 1.5 billion people are dependent on the underground source of water. Groundwater quality is greatly affected by subsurface geology, topography, climate change, and natural events such as earthquakes, floods, and landslides. This chapter presents a holistic approach to the geogenic pollutants, including their mineralogical sources, remedial measures, and impact on human health in different geographical regions of India. The geogenic pollutant is defined as the surpassing of certain thresholds regarding drinking water recommendations in subsurface water systems devoid of direct or indirect anthropogenic intervention. Longer residence time, often combined with favourable geologic conditions and mineralogy of the aquifer, lead to groundwater pollution by geogenic contaminants. The commonly known geogenic pollutants are arsenic (As), fluoride (F), iodine (I), uranium (U), sodium (Na), chloride (Cl), sulphate (SO4), and trace elements such as iron (Fe), manganese (Mn), chromium (Cr), selenium (Se), etc. As and F are widely studied geogenic pollutants in various geographical regions. The mechanism behind the As mobilization under alkaline and reducing conditions is identified as reductive dissolution of As‐bearing Fe minerals, reductive desorption of As(V), and formation of readily mobile complexes, whereas F enrichment is affected by the solubility of F‐bearing minerals, restriction of groundwater conditions, and the presence of precipitating or complexing ions.
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 (< 50 m) hydrogeochemistry in arsenic mobilization are known to be a viable tool to explain the arsenic menace in shallow groundwater. The present investigation emphasizes the hydrogeochemical driver and/or control over the reductive dissolution of Fe-bearing host minerals and thereby releasing arsenic into the shallow groundwater of the study area. The study suggests that hydrogeochemical evolution is mainly governed by carbonate minerals dissolution, silicate weathering, and competitive ion-exchange processes in the shallow aquifers (< 50 m). The present study also indicates the prevalence of carbonate minerals dissolution over silicate weathering. The emergence of Cl− concentration in the shallow groundwater founds the possibilities of anthropogenic inputs into the shallow aquifers (< 50 m). The reducing environment in shallow aquifers (< 50 m) of the study area is evident in the reductive dissolution of Fe- bearing shallow aquifer minerals which absorb arsenic in the solid phase and mobilize arsenic onto shallow groundwater. The study opted for many statistical approaches to delineate the correlation among major and minor ionic constituents of the groundwater which are very helpful to understand the comprehensive mechanism of arsenic mobilization into shallow groundwater.
Inactivation of chicken liver xanthine dehydrogenase by arsenite is reflected in the molybdenum electron paramagnetic resonance signal at g = 1.97. The arsenite spectrum shows additional splittings and considerable broadening yet remains comparable to the native in total intensity. Further subtle alterations of the molybdenum signal of arsenite-treated enzyme are seen in the presence of purine-type substrates or inhibitors.