The present study was carried out in the village Kaliprasad of Bhagalpur district of Bihar to know the arsenic exposure effect in the exposed population. A total of n = 102 households were studied, and their water and biological samples such as urine and hair were collected and analyzed in a graphite furnace atomic absorption spectrophotometer (GF-AAS). The assessment of arsenic-exposed village population reveals that the villagers were suffering from serious health-related problems such as skin manifestations (hyperkeratosis and melanosis in their palm and soles), breathlessness, general body weakness, mental disorders, diabetes, hypertension (raised blood pressure), hormonal imbalance, neurological disorders, and few cancer cases. About 77% of household hand pump water had arsenic level more than the WHO recommended level of 10 µg/L, with highest level of 523 µg/L. Moreover, in 60% individual’s urine samples, arsenic concentration was very high with maximum 374 µg/L while in hair 64% individuals had arsenic concentration above the permissible limit with maximum arsenic concentration of 11,398 µg/kg. The hazard quotient (HQ) was also calculated to know the arsenic risk percentage in children as 87.11%, in females as 83.15%, and in males as 82.27% by groundwater. This has surpassed the threshold value of 1 × 10 - 6 for carcinogenic risk (CR) in children, female, and male population group in the village. Hence, the exposed population of Kaliprasad village are at very high risk of the disease burden.@en

Shallow aquifers in many Holocene alluvial basins around the world have in the last three decades been identified as arsenic pollution hotspots, in which the spatial variation of natural (or: geogenic) arsenic concentration is conditioned by the meandering-river geomorphology and the fluvial lithofacies distribution. Despite the large amount of publications on the specifics of the pollution, still many uncertainties remain as to the provenance and processes that lead to arsenic enrichment in aquifers. In this paper, arsenic in abandoned and sediment-filled meandering-river bends (or: clay-plugs) is highlighted as a primary source of aquifer pollution. The combination of high organic-carbon deposition rates and the presence of chemically-bound natural arsenic in sediment of this specific geomorphological setting creates the potential for microbially-steered reductive dissolution of arsenic in an anoxic environment, and subsequent migration of the desorbed arsenic to, and stratigraphic entrapment in, adjacent sandy point-bar aquifers. To assess the magnitude of the arsenic source in clay-plug, bulk sediment volume calculations were made of twenty clay plugs on the Middle Ganges Plain of Bihar (India), by combining clay-plug surface area analysis of Sentinel-2 satellite data, side-scan sonar depth profiling of oxbow lakes and the Ganges River, and sedimentological data from five cored shallow wells. ICP-MS based elemental analysis of 36 core sub-samples, complemented with published concentration data in a similar geomorphological setting in West Bengal, India, yielded an average arsenic content of 28.75 mg/kg sediment in the 12-m-thick clay plugs, which amounts to a total arsenic volume of 0.07 – 3.13 . 106 kg per clay plug. A scenario is presented for the release of arsenic from the clay-plug sediment by microbial metabolism, followed by migration of the desorbed arsenic to the bordering point-bar sands.@en

Arsenic poisoning through groundwater is the world’s greatest normal groundwater catastrophe which got an immense effect on worldwide general wellbeing. India is confronting the outcomes of arsenic poisoning in the zone of Ganga Brahmaputra alluvial plains. In Bihar, out of 38 districts, 18 districts are exceptionally influenced with groundwater arsenic defilement. In the present study, we have assessed the current situation of arsenic exposure in Sabalpur village of Saran district of Bihar after reporting of breast, renal, skin and thyroid cancer cases from this village along with typical symptoms of arsenicosis. Such cancer patients were identified at our institute and were taken for the study. The present investigation deals with the quantification of arsenic in groundwater, hair and nail samples of subjects as well as the survey of entire village to know the overall health status of the village people. A total of n=128 household handpump water samples as well as n=128 human hair and nail samples were collected from over n=520 households. Using the graphite furnace atomic absorption spectrophotometer (GF-AAS), all the samples were analysed. The investigation resulted that the 61% of the analysed samples particularly the groundwater had the arsenic levels more than the permissible limit of WHO (> 10 μg/L) with 244.20 μg/L as the highest arsenic contamination in one of the handpump water sample. The exposure effect of hair sample was worst as 88% of all the collected samples were having high arsenic levels more than the permissible limit (> 0.2 mg/Kg). In case of nail samples, 92% of the samples were having high arsenic concentration more than the permissible limit (> 0.5 mg/Kg). The health survey study revealed high magnitude of disease burden in the exposed population with symptoms such as asthma, anaemia, hepatomegaly, diabetes, cardiac problem, skin fungal infections, breathlessness and mental disability. Few cancer cases of renal, skin, breast and cervix were also found among the exposed population of this village. The percentage of cancer cases in this village was 0.94% that was low, but it would be an aggravated situation in the near future if people will continue drinking arsenic-contaminated water. Therefore, a mitigation intervention was carried out in March 2020 by installing an arsenic filter plant. The health situation in the village in the present scenario is hope to improve in the coming years. However, motivation and awareness among the village population are still required.@en

Meandering-river geomorphology, forming abandoned channels/lakes with organic carbon-burial and microbial reductive dissolution, play many crucial roles in controlling arsenic (As) fluxes in sinks such as contaminated aquifers of riverine alluvial plains across the world. Suhiya oxbow-lake in the middle alluvial plain of the River Ganga, was selected as the natural laboratory. A top-down multidisciplinary approach was chosen employing satellite imagery to analyse the annual oxbow-lake surface vegetation dynamics (Eichhornia and Hydrilla). Side-scan sonar profiles across two oxbow lakes along with River Ganga core data and vintage topographical maps, estimated the lake-sedimentation rate of 9.6 cm/yr. Organic carbon [amino acids, aromatics, lingo-phenols and lipids hydrocarbons] infiltration-based on hydrophobicity and molecular-mass was detected at different depths along the water and sedimentary column. Elemental analysis showed lake surface to groundwater the As conc. varied from (0.37 to 185 μg/l). A microbial diversity based study showed that large sized photoautotrophs Nostoc, Anabaena are replaced by Fe-oxido-reducing As-metabolizing bacteria e.g. Acidovorax, Dechloromonas and enteric organisms e.g. Enterobacter, Salmonella at bottom of water column. Based on these inferences, a conceptual organic carbon transport model was constructed to understand the preferential preservation and microbial diagenesis resulting in mobilization of As and other geogenic elements.@en

Reportedly, 300 million people worldwide are affected by the consumption of arsenic contaminated groundwater. India prominently figures amongst them and the state of Bihar has shown an upsurge in cases affected by arsenic poisoning. Escalated arsenic content in blood, leaves 1 in every 100 human being highly vulnerable to being affected by the disease. Uncontrolled intake may lead to skin, kidney, liver, bladder, or lung related cancer but even indirect forms of cancer are showing up on a regular basis with abnormal arsenic levels as the probable cause. But despite the apparent relation, the etiology has not been understood clearly. Blood samples of 2000 confirmed cancer patients were collected from pathology department of our institute. For cross-sectional design, 200 blood samples of subjects free from cancer from arsenic free pockets of Patna urban agglomeration, were collected. Blood arsenic levels in carcinoma patients as compared to sarcomas, lymphomas and leukemia were found to be higher. The geospatial map correlates the blood arsenic with cancer types and the demographic area of Gangetic plains. Most of the cancer patients with high blood arsenic concentration were from the districts near the river Ganges. The raised blood arsenic concentration in the 2000 cancer patients strongly correlates the relationship of arsenic with cancer especially the carcinoma type which is more vulnerable. The average arsenic concentration in blood of the cancer patients in the Gangetic plains denotes the significant role of arsenic which is present in endemic proportions. Thus, the study significantly correlates and advocates a strong relation of the deleterious element with the disease. It also underlines the need to address the problem by deciphering the root cause of the elevated cancer incidences in the Gangetic basin of Bihar and its association with arsenic poisoning.@en

The Ganges Delta is a key area where elemental contamination of groundwater constitutes a human catastrophe. The delta plain geomorphology comprises a large number of abandoned meander bends or oxbow lakes (Donselaar et al., 2017; Ghosh et al., 2021) characterized by an anoxic environment in the lower part of the lake water column (hypolimnion). Here we present the critical role of these abandoned-river channels forming oxbow lakes. The geomorphological the juxtaposition of (a) abandoned channels (or: oxbow lakes) where the cocktail of organic matter and sediment leads to the release of various elements, (b) the topographically higher point bars where the released elements accumulate in the aquifer and provide a blueprint to explain the origin and localization of elemental toxicity. Dissolved organic matter (DOM) is implicated in the mobilization of elements via microbial metabolic processes. Organic matter (OM) is preserved in this environment and provides a perfect environment for microbial oxidation and mobilization of Fe-oxides. Additional deposition of human-introduced sewage wastes adds to a rich source of nutrients to the indigenous microbial communities. A multidisciplinary approach was effective in understanding the geomorphology of river meanders, forming abandoned channels, which act as a growth bed for biomass. While acting as an incubator for primary production (lake vegetation dynamics), and subsequent organic debris accumulation (anoxic, hypolimnion water column), where selective preferential preservation of organic carbon compound (anoxic sediment base) occur. We have described how organic compound infiltration, deposition and abundance depends on their hydrophobicity, molecular weights and bioavailability and further, due to diagenetic alteration (microbial metabolic oxidation). Different classes of surface derived organic carbon from vegetation with anthropogenic inputs, can have different effects on the mineral weathering and in controlling the downstream cationic fluxes such as Fe, Mn, As, F etc. and contamination of aquifers in various river plains across the world. @en

In recent times Gallbladder cancer (GBC) incidences increased many folds in India and are being reported from arsenic hotspots identified in Bihar. The study aims to establish association between arsenic exposure and gallbladder carcinogenesis. In the present study, n = 200 were control volunteers and n = 152 confirmed gallbladder cancer cases. The studied GBC patient’s biological samples-gallbladder tissue, gallbladder stone, bile, blood and hair samples were collected for arsenic estimation. Moreover, n = 512 gallbladder cancer patients blood samples were also evaluated for the presence of arsenic to understand exposure level in the population. A significantly high arsenic concentration (p < 0.05) was detected in the blood samples with maximum concentration 389 µg/L in GBC cases in comparison to control. Similarly, in the gallbladder cancer patients, there was significantly high arsenic concentration observed in gallbladder tissue with highest concentration of 2166 µg/kg, in gallbladder stones 635 µg/kg, in bile samples 483 µg/L and in hair samples 6980 µg/kg respectively. Moreover, the n = 512 gallbladder cancer patient’s blood samples study revealed very significant arsenic concentration in the population of Bihar with maximum arsenic concentration as 746 µg/L. The raised arsenic concentration in the gallbladder cancer patients’ biological samples—gallbladder tissue, gallbladder stone, bile, blood, and hair samples was significantly very high in the arsenic exposed area. The study denotes that the gallbladder disease burden is very high in the arsenic exposed area of Bihar. The findings do provide a strong link between arsenic contamination and increased gallbladder carcinogenesis.@en