Groundwater In Bangladesh Research Articles

Study on the Relationship between Groundwater and Land Subsidence in Bangladesh Combining GRACE and InSAR

Due to a heavy reliance on groundwater, Bangladesh is experiencing a severe decline in groundwater storage, with some areas even facing land subsidence. This study aims to investigate the relationship between groundwater storage changes and land subsidence in Bangladesh, utilizing a combination of GRACE and InSAR technologies. To clarify this relationship from a macro perspective, the study employs GRACE data merged with GLDAS to analyze changes in groundwater storage and SBAS-InSAR technology to assess land subsidence. The Dynamic Time Warping (DTW) method calculates the similarity between groundwater storage and land subsidence time series, incorporating precipitation and land cover types into the data analysis. The findings reveal the following: (1) Groundwater storage in Bangladesh is declining at an average rate of −5.55 mm/year, with the most significant declines occurring in Rangpur, Mymensingh, and Rajshahi. Notably, subsidence areas closely match regions with deeper groundwater levels; (2) The similarity coefficient between the time series of groundwater storage and land subsidence changes exceeds 0.85. Additionally, land subsidence in different regions shows an average lagged response of 2 to 6 months to changes in groundwater storage. This study confirms a connection between groundwater dynamics and land subsidence in Bangladesh, providing essential knowledge and theoretical support for further research.

Pervasiveness and classification of microplastics in Landfill Leachate: Impacts, Risks, and Treatment Efficiency

Microplastics (MPs) in surface and groundwater in Bangladesh are a significant issue. The purpose of this research was to assess the possibility of landfill leachate acting as a potential origin of MPs and to determine if the surrounding surface water (SW) and groundwater (GW) act as recipients. Furthermore, this research assessed the leachate treatment plant MP removal efficacy and MP risk assessment. The findings show that discharge leachate from the Matuail landfill contributes 3.5 × 108 particles per hour to the surrounding aquatic environment, with an average of 350 ±10 MPs/L. MPs was found highly in SW and then in GW with an average of 1683 ± 70 and 614 ± 40 MPs/L, respectively, with 48.9% of MPs ranged from 0.1mm to 0.5mm. The dominant shapes were fibers and fragments. The Fourier transform infrared spectroscopy (FTIR) analysis revealed low density polyethylene (LDPE), high density polyethylene (HDPE), and Polypropylene (PP) was the most common, and Polyurethane (PUR), Polymethyl methacrylate (PMMA), and Polyacrylonitrile (PAN) posed the greatest threat to the environment. The inefficient treatment method resulted in the release of 83.33% of MPs, indicating a low removal efficiency in the leachate. The inefficient removal rate leads to the highest pollutant load index for surface water (2.18). Ultimately, the analysis of the nemerow pollution index (NPI), contamination factor (CF), pollution load index (PLI), polymer hazard index (PHI), and potential ecological risk (Ei), revealed a minimal to extremely high range of contaminations. A clear link was obsevered between the particles shape and size throught the principal component analysis (PCA). Moreover, it highlights the need for ongoing national surveillance of MPs considering the gravity of this contamination and indicates the importance of proactive management of landfill sites.

Determination of water quality and efficient removal of arsenic and iron from groundwater using mahogany fruit husk and banana peduncle charcoals

The groundwater (GW) of Bangladesh is predominantly contaminated with arsenic (As) and iron (Fe) which has a bad impact on human health. We tried to remove these elements with easily available mahogany-fruit (Swietenia mahagoni) husk charcoal (MHC) and banana (Musa acuminata) peduncle charcoal (BPC). The trial was implemented with 3 replications throughout the research. The sampled GW contained 0.06 mg As L−1 and 4.83 mg Fe L−1. Firstly, the pH was 3, 5, 7, and 9 with a 250 mg L−1 dose. The MHC removed almost 91.05 % of As at pH 5.0, and BPC removed almost 86.67 % of As at pH 9. However, in the case of Fe, the MHC removed almost 100 % at pH 7 and 9; and BPC removed the same quantity at pH 5, 7, and 9. Secondly, the contact times were 0, 5, 10, 20, and 40 min with a 250 mg L−1 dose at pH 7.0. The maximum removal of As and Fe was 100 % with MHC and BPC at 5 min. The pseudo-first-order kinetic, pseudo-second-order kinetic, and intra-particle diffusion models were considered. The result showed that the rate of adsorption followed the pseudo-second-order kinetic model. Lastly, the adsorbent doses were 0, 50, 150, 250, and 350 mg L−1. At pH 7, the highest removal of As was 79.47 % and Fe removal was 100 % at 350 mg L−1 dose for MHC. Similarly, the values were 79.29 % and 100 % for the same at 350 mg L−1 dose of BPC, indicating these charcoal are good for heavy metals removal.

Modeling spatial groundwater level patterns of Bangladesh using physio-climatic variables and machine learning algorithms

Groundwater monitoring is essential for sustainable groundwater resource management in a country like Bangladesh, where this precious resource is gradually declining due to over-extraction. However, traditional methods of acquiring groundwater level (GWL) data over a large area are time-consuming and expensive. To address this, this study proposes an alternative approach using freely available daily groundwater storage (GWS) gridded data from the Global Land Data Assimilation System (GLDAS) and other data sources such as population, rainfall, temperature, irrigation, and elevation. By employing different regression and machine learning models like multiple linear regression (MLR), regression trees, support vector machines (SVM), Gaussian process regression (GPR), and artificial neural networks (ANN), the study aimed to model GWL data for Bangladesh at a spatial resolution of 0.25° × 0.25°. In-situ weekly GWL data collected from 844 locations across the country were used for model development. The results indicated that GWS data alone was insufficient to estimate the spatial variability and trend of groundwater in Bangladesh. However, the comparison of different models showed that the ANN model performed better, with an overall correlation coefficient (R) of 0.95 and mean squared error (MSE) of 0.64 m2 when estimating GWL using GWS and other data. The study also identified population and rainfall as the most influential factors in determining GWL. The developed ANN model can be utilized to estimate GWL at locations where observation data are unavailable, enabling the monitoring of GWL for sustainable groundwater management in Bangladesh.

Salinisation of drinking water ponds and groundwater in coastal Bangladesh linked to tropical cyclones

Salinity is a widespread problem along the Asian coast, mainly in reclaimed lands where most people live. These low-lying areas are vulnerable to impacts from tropical cyclone induced storm surges. The role of such surges on the long-term salinity of water resources, particularly the salinisation of drinking water ponds, a key water resource, requires further investigation. Here we show, using high-resolution measurements of pond hydrology and numerical modelling, that episodic inundation events cause the widespread salinisation of surface water and groundwater bodies in coastal areas. Sudden salt fluxes in ponds cause salinity build-up in the underlying sediments and become a source of salinity. Rapid clean-up of drinking ponds immediately after a surge event can significantly minimize these salinity impacts, which are likely to increase under climate change. Our study has implications for coastal land use and water resources management in tropical deltas.

Iron, manganese, and lead contamination in groundwater of Bangladesh: a review

Abstract Groundwater is a vital source of safe drinking water in Bangladesh and most South Asian countries. The study aimed to identify the sources and assess the contamination of Fe, Mn, and Pb in groundwater. The study considered published articles, reports, and data repositories of concerned departments over the past two decades using various search engines, including Web of Science, Scopus, Science Direct, Google Scholar, etc. The study results showed the concentrations of Fe, Mn, and Pb in groundwater exceeded 55.93, 75.44, and 37.50%, respectively, of different standards, including the World Health Organization and United Nations Environmental Protection Agency. The concentrations of Fe, Mn, and Pb ranged from 0.003 to 16.6, 0.00063 to 3.11, and 0.0006 to 5.01 mg/L, respectively, and followed the order Fe > Mn > Pb in the groundwater of Bangladesh. Sources of Fe and Mn in groundwater are mostly geogenic in origin, while Pb contamination in groundwater is anthropogenic and derives from industry dust piles, vehicle exhaust discharge, lead pipes, faucets, fixtures, and batteries. The higher levels of heavy metals in groundwater cause health and environmental hazards. The study recommended that the higher concentrations of Fe, Mn, and Pb in groundwater make it unsuitable for drinking purposes and should be treated before consumption.

Metagenomic and culture-dependent approaches unveil active microbial community and novel functional genes involved in arsenic mobilization and detoxification in groundwater

BackgroundArsenic (As) and its species are major pollutants in ecological bodied including groundwater in Bangladesh rendering serious public health concern. Bacteria with arsenotrophic genes have been found in the aquifer, converting toxic arsenite [As (III)] to less toxic arsenate [As (V)] that is easily removed using chemical and biological trappers. In this study, genomic and metagenomic approaches parallel to culture-based assay (Graphical abstract) have made it possible to decipher phylogenetic diversity of groundwater arsenotrophic microbiomes along with elucidation of their genetic determinants.ResultsSeventy-two isolates were retrieved from six As-contaminated (average As concentration of 0.23 mg/L) groundwater samples from Munshiganj and Chandpur districts of Bangladesh. Twenty-three isolates harbored arsenite efflux pump (arsB) gene with high abundance, and ten isolates possessing arsenite oxidase (aioA) gene, with a wide range of minimum inhibitory concentration, MICAs (2 to 32 mM), confirming their role in arsenite metabolism. There was considerable heterogeneity in species richness and microbial community structure. Microbial taxa from Proteobacteria, Firmicutes and Acidobacteria dominated these diversities. Through these combinatorial approaches, we have identified potential candidates such as, Pseudomonas, Acinetobacter, Stenotrophomonas, Achromobacter, Paraburkholderia, Comamonas and Klebsiella and associated functional genes (arsB, acr3, arsD, arsH, arsR) that could significantly contribute to arsenite detoxification, accumulation, and immobilization.ConclusionsCulture-dependent and -independent shotgun metagenomic investigation elucidated arsenotrophic microbiomes and their functions in As biogeochemical transformation. These findings laid a foundation for further large-scale researches on the arsenotrophic microbiomes and their concurrent functions in As biogeochemical transformation in As-contaminated areas of Bangladesh and beyond.

Nitrate Pollution in the Groundwater of Bangladesh: An Emerging Threat

Access to safe potable water is one of the most significant challenges in an environmentally vulnerable country like Bangladesh. The presence of high concentrations of nitrate in groundwater can deteriorate its quality and pose serious health threats. A review was conducted to evaluate the current status of overall nitrate concentrations in different districts (35 out of 64 districts) of Bangladesh based on available published data. Human Health Risk Analysis (HHRA) and nitrate pollution index (NPI) were calculated to illustrate the level of chronic risk and degree of pollution among the population of the studied districts. The HHRA model predicted that the adult population of 48.57% districts and the child population of 56.25% districts were found to be facing potential health risks associated with elevated nitrate consumption. The NPI results revealed that at least 45.72% of the studied districts were characterized by light to very significant nitrate pollution loads. It can be concluded that the outcomes of this systematic study would draw the attention of policymakers and the population of all districts and enable them to take effective measures in preserve groundwater resources in Bangladesh and prevent long-term, complex diseases.

Investigation of isotopic ratio (234U/238U), chemotoxicity and radiotoxicity of dissolved uranium in selected groundwater of Bangladesh

Investigation of isotopic ratio (234U/238U), chemotoxicity and radiotoxicity of dissolved uranium in selected groundwater of Bangladesh

GROUNDWATER USE EFFICIENCY FOR SUSTAINABLE AGRICULTURE: PROSPECTS IN BANGLADESH

Bangladesh is a developing country where contribution of agriculture in national GDP (Gross Domestic Product) is 12.68%. In agricultural sector, about 79% irrigation has been provided by groundwater. The extensive installation of deep tubewells (34,332) and shallow tubewells (1,483,332), in last two decades, helps in maximum utilization of groundwater which is leading Bangladesh to reach near to the self-sufficiency in rice production (35.3 metric tons in 2019). But the continuous production of boro rice in the dry season is a threat for groundwater use efficiency. Again, without sufficient irrigation water, assuring sustainable agriculture is not feasible. This review paper had been prepared on the developing scenario of groundwater and its utilization efficiency, problems in groundwater use and relevant remedies to attain sustainable agriculture in Bangladesh. Due to the over extraction of groundwater, the depth of groundwater table has been declined (15%) miserably. Using redundant amount of irrigation water, conveyance loss (8-40%), arsenic contamination, insufficient recharge of groundwater etc. are the major problems behind inadequate groundwater use efficiency. Using Alternate Wetting and Drying (AWD) method, reducing conveyance loss, diversifying cropping pattern, reforming national policies etc. are some effective measures to increase groundwater use efficiency required for sustainable agriculture. About 10,000 tk/ha can be saved just by minimizing the cost required to extract excess groundwater for irrigation. In Bangladesh, maximum national policies are focusing exclusively to the resource development rather than the resource management. The awareness can be built through different teaching programs among all the stakeholders. Rather than just imposing restriction on installation of tubewells, more constructive policies have to be announced by the policy makers. Seven different agencies are now working for the management of groundwater in Bangladesh. Besides other technical solutions, there should be a connection between different organizations related to the groundwater management for the effective implementation of their target policies.

Arsenic and Salinity Affected Groundwater in South-Western Bangladesh: An Assessment of Managed Aquifer Recharge and Sub-Surface Arsenic Removal as Mitigation Techniques

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.

Geogenic manganese and iron in groundwater of Southeast Asia and Bangladesh – Machine learning spatial prediction modeling and comparison with arsenic

Naturally occurring, geogenic manganese (Mn) and iron (Fe) are frequently found dissolved in groundwater at concentrations that make the water difficult to use (deposits, unpleasant taste) or, in the case of Mn, a potential health hazard. Over 6000 groundwater measurements of Mn and Fe in Southeast Asia and Bangladesh were assembled and statistically examined with other physicochemical parameters. The machine learning methods random forest and generalized boosted regression modeling were used with spatially continuous environmental parameters (climate, geology, soil, topography) to model and map the probability of groundwater Mn > 400 μg/L and Fe > 0.3 mg/L for Southeast Asia and Bangladesh. The modeling indicated that drier climatic conditions are associated with a tendency of elevated Mn concentrations, whereas high Fe concentrations tend to be found in a more humid climate with elevated levels of soil organic carbon. The spatial distribution of Mn > 400 μg/L and Fe > 0.3 mg/L was compared and contrasted with that of the critical geogenic contaminant arsenic (As), confirming that high Fe concentrations are often associated with high As concentrations, whereas areas of high concentrations of Mn and As are frequently found adjacent to each other. The probability maps draw attention to areas prone to elevated concentrations of geogenic Mn and Fe in groundwater and can help direct efforts to mitigate their negative effects. The greatest Mn hazard is found in densely populated northwest Bangladesh and the Mekong, Red and Ma River Deltas of Cambodia and Vietnam. Widespread elevated Fe concentrations and their associated negative effects on water infrastructure pose challenges to water supply. The Mn and Fe prediction maps demonstrate the value of machine learning for the geospatial prediction modeling and mapping of groundwater contaminants as well as the potential for further constituents to be targeted by this novel approach.

Highly efficient size-sieving-based removal of arsenic(III) via defect-free interfacially-polymerized polyamide thin-film composite membranes

Serious health problems have been linked to the consumption and exposure of arsenic-contaminated groundwater. In comparison to As(V), As(III) is smaller and predominantly present in its neutral form in groundwater, which hinders its efficient removal by conventional nanofiltration and reverse osmosis membranes. In this study, the removal of As(III) was investigated at different pH conditions using three defect-free interfacially polymerized thin-film composite (TFC) membranes made by an optimized in-house developed interfacial polymerization process (KRO). The membranes were fabricated from aromatic para-phenylenediamine (PPD) or meta-phenylenediamine (MPD) and cycloaliphatic piperazine (PIP) by reaction with trimesoyl chloride (TMC). The PPD-KRO, MPD-KRO, and PIP-KRO polyamide membranes were tested with a feed containing 5 ± 1 mg L−1 (ppm) As(III). Two commercial TFC membranes, a seawater (Sepro RO4) and a nanofiltration (DOW NF270) membrane, were also evaluated for comparison. At natural conditions (pH 6–8), the defect-free fully aromatic TFC membranes demonstrated unprecedented size-sieving performance for As(III) removal with a rejection of ∼99.5 and > 99.8% for PPD-KRO and MPD-KRO, respectively, in comparison to ∼95% for the commercial Sepro RO4 seawater membrane tested under the same conditions. In contrast, As(III) rejection of semi-aromatic piperazine-based TFCs, PIP-KRO and NF270, showed a strong dependence on the charge-exclusion mechanism with maximum As(III) rejections of 69.5 and 46.3% at pH 10, respectively. Most notably, we demonstrated that the MPD-KRO membrane achieved an As(III) concentration ∼5 μg L−1 in the permeate (less than the WHO permissible arsenic standard level of 10 μg L−1), whereas PPD-KRO achieved a slightly higher value of ∼14 μg L−1. Our results are very promising considering the arsenic standard level in highly As(III) contaminated groundwater in Bangladesh and India is set at 50 μg L−1.

Summary of four scientific studies on Arsenicum album high dilution effect against Arsenic intoxication in mice

Background: Groundwater arsenic affects millions of people in about 20 countries. In West Bengal (India) and Bangladesh alone over 100 million people are exposed. The arsenic concentration in contaminated groundwater in Bangladesh was above the maximum permissible level of 0.05 mg/l as recommended by WHO for developing countries [1]. Drinking water is not the only source of poisoning. In arsenic contaminated areas, crops, vegetables, cereals, poultry, cattle, etc, also contain traces of arsenic. Chronic arsenic intoxication has been associated with several diseases such as melanosis, leuco-melanosis, hyperkeratosis, oedema, skin cancer… 
 Cazin et al [2], have demonstrated the effect of high dilutions of arsenic compounds. They noted increased arsenic elimination from blood through urine and faeces in intoxicated rats. According to these research, the aim of Khuda Buksh studies [3-4-5] was to investigate whether high dilution Arsenicum album have any effect on arsenic accumulation in different tissues and to understand also how this high dilution could produce a protective effect on all the different organs.
 Methodology: Firstly, the effect of Arsenicum album 30 cH on the amount of arsenic accumulation was determined by spectrophotometric analysis in four tissues namely liver, kidney and testis in mice intoxicated by arsenic. The protective effect in chronic and acute arsenic intoxicated mice of Arsenicum Album 6cH, 30cH and 200cH has been evaluated using not only the activities of enzymatic and biomarker toxicity (aspartate amino transferase (AST), alanine amino transferase (ALT), acid phosphatase (AcP), alkaline phosphatase (AlkP), lipid peroxidation (LPO) and reduced glutathione (GSH)) but also the cytogenetical parameters (chromosome aberrations (CA), mitotic index (MI), sperm head anomaly (SHA) etc., ). Because, it is well demonstrated that these enzymes biomarkers reflect the degree of hepatotoxicity and oxidative stress caused by arsenic intoxication.
 Results: Compared to controls, Arsenicum album 30cH induced a significant decrease in accumulation of arsenic in 4 tissues namely liver, spleen, kidney and testis in intoxicated mice. In addition, both Arsenicum album 6cH, 30cH and 200cH reduced chromosome aberrations, sperm head abnormality frequencies and activities of acid and alkaline phosphatases, aspartate and alanine aminotransferases and lipid peroxidation, while mitotic index and activities of glutathione, catalase and succinate dehydrogenase were increased compared to controls. 
 Conclusion: Altogether, theses results provide evidence of protective potentials of the Arsenicum album dilution against acute and chronic arsenic intoxication in mice. They also offer a new hypothesis that the mechanism of the homeopathic dilution could act through regulation of expression of certain genes. This explanation seems to be plausible because all biomarker tests are regulated by specific genetic regulatory mechanisms [6].
 keywords: Arsenicum album, arsenic intoxication, enzymatic and biomarker toxicity.

The Influence of Weathering, Water Sources, and Hydrological Cycles on Lithium Isotopic Compositions in River Water and Groundwater of the Ganges–Brahmaputra–Meghna River System in Bangladesh

The silicate weathering of continental rocks plays a vital role in determining ocean chemistry and global climate. Spatiotemporal variations in the Li isotope ratio (δ7Li) of terrestrial waters can be used to identify regimes of current and past weathering processes. Here we examine: 1) monthly dissolved δ7Li variation in the Ganges River’s lower reaches; and 2) the spatiotemporal variation of river water of the Brahmaputra, Meghna rivers, and groundwater in Bangladesh. From the beginning to maximum flood discharges of the rainy season (i.e., from June to September), Li concentrations and δ7Li in the Ganges River show remarkable changes, with a large influence from Himalayan sources. However, most Li discharge across the rainy season is at steady-state and strongly influenced by the secondary mineral formation in the low-altitude floodplain. Secondary mineral formation strongly influences the Meghna River’s Li isotopic composition along with fractionation lines similar to the Ganges River. A geothermal input is an additional Li source for the Brahmaputra River. For groundwater samples shallower than ∼60 m depth, both δ7Li and Li/Na are highly scattered regardless of the sampling region, suggesting the variable extent of fractionation. For deep groundwater (70–310 m) with a longer residence time (3,000 to 20,000 years), the lower δ7Li values indicate more congruent weathering. These results suggest that Li isotope fractionation in rivers and groundwater depends on the timescale of water-mineral interaction, which plays an essential role in determining the isotopic signature of terrestrial Li inputs to the ocean.

Groundwater Quality and Risk Assessment of Heavy Metal Pollution in Middle-West Part of Bangladesh

Bangladesh is a densely populated and developing country that faced severe water contamination, crisis, and security. About 100% of the population has access to the availability of freshwater, but the purity of water is always concerned. The groundwater of Bangladesh is under increasing threat from overexploitation, population growth, rapid urbanization, and pollution from industries, domestic and agricultural sources. For the assessment of heavy and toxic metal contamination in shallow groundwater, the study collected 40 water samples from different stations in the middle-west part of Bangladesh. The results showed that three metals ion, viz. iron, manganese, and lead exceeded the concentration limit of WHO (2011) in most of the water samples indicating severe human health hazard. The single-factor pollution index (I i ) and compound pollution index (CPI) value of these three (3) metals were very high, i.e., much greater than 1. The other metal concentrations were found within the safe permissible ranges. The values of heavy metal pollution indices, viz. heavy metal pollution index (HMPI), heavy metal evaluation index (HMEI), degree of contamination (Cd ), Nemerow Index (NeI), and ecological risk measurement (ERI) showed that most of the water samples were found medium to high levels of contamination in the study area. The analysis results revealed that an average of 32.6%, 15.6%, and 51.8% of the water samples was found low, medium, and high risk from heavy metal, respectively. There were 20 samples found highly contaminated with heavy metals out of 40 samples. The study results revealed that both the geogenic and anthropologic activities influenced the groundwater system of the area. It suggested that the groundwater quality should go under a continuous monitoring process for sustainable water quality management in the area. The study findings could help with further planning of potential future remediation measures for policymakers.

Assessing the Removal of Arsenite and Arsenate Mixtures from the Synthetic Bangladesh Groundwater (SBGW) Using Combined Fe(VI)/Fe(III) Treatments and Local Regression Analysis

Arsenic is an inorganic pollutant that, depending on oxidation–reduction and pH level conditions, may be found in natural waters in two variants: As(III) and As(V). Any treatment to effectively remove arsenic from water will be conditioned by the presence of one or both variants. In this context, this study assesses using electrochemically produced Fe(VI) with Fe(III) to remove As(III), As(V), and their combinations from the Synthetic Bangladesh Groundwater (SBGW) containing anions that interfere with iron-based arsenic removal processes. The combined use of Fe(VI) and Fe(III) allowed us to remove the total arsenic below the 10 mg L−1 threshold established by the World Health Organization and Peruvian regulations for drinking water. An optimum combination of 1 mg L−1 of Fe(VI) and 30 mg L−1 of Fe(III) was identified and tested on the removal of four different proportions of As(III):As(V) for two total concentrations: 500 and 250 mg L−1. There were no significant differences in the final removal values under the different proportions of As(III):As(V) for each total concentration, with a final removal average of 99.0% and 96.9% for the 500 and 250 µg L−1 concentrations, respectively.

Iron in groundwater: quality evaluation, health risk, and spatial distribution in Rangpur City Corporation

High iron (Fe)–bearing groundwater in Bangladesh contaminates the groundwater aquifer with subsequent health risk. All the populations of Rangpur City Corporation (RpCC) depend on groundwater for their drinking, domestics, and irrigation purposes. This study investigates the concentration of Fe in groundwater of RpCC with special attention on the associated health risk of the dwellers residing in it. Stratified random sampling was adopted to collect 101 water samples from 33 wards of which each ward has 3 samples from tube well to identify Fe concentration using atomic absorption spectroscopy (AAS). The data are analyzed following several statistical technique and compared with Bangladesh and WHO standard values. Maximum mean concentration was found in ward no. 11which is 1.620 mg/L and minimum mean concentration was found in ward no. 6 which is 0.006 mg/L. Single Factor Index (SFI) and Nemerow Index (NI) were applied to analyze the quality of groundwater for the whole data set. Hazard Quotient (HQ) and Hazard Index (HI) were used to assess health risk and it ensures that the females of the study area are more susceptible to iron health risk than the males. However, geostatistical analyses using ArcGIS-10.5 were used to show the spatial distribution and autocorrelation among several variables. Spatial distribution maps show important visualization for understanding Fe concentration zoning, distribution of quality indices, and health risk. The findings of this work will help the city corporation authority, environmental planner, and policymaker to understand the potential health risk due to Fe concentration.

Stable Strontium Isotopic Compositions of River Water, Groundwater and Sediments From the Ganges–Brahmaputra–Meghna River System in Bangladesh

The Sr isotopic composition of rivers and groundwaters in the Bengal Plain is a major contributor to the global oceanic Sr inventory. The stable strontium isotope ratios (δ88Sr) provide a new tool to identify chemical weathering reactions in terrestrial water. In this study, we investigated the spatiotemporal variations of δ88Sr in samples of river water, bedload sediment, and groundwater collected from the Ganges–Brahmaputra–Meghna drainage basin in Bangladesh, which is known to strongly influence the 87Sr/86Sr ratio in seawater. The average δ88Sr values of waters of the Ganges, Brahmaputra, and Meghna rivers were 0.269, 0.316, and 0.278‰, respectively. Our data showed little difference between seasons of high and low discharge. The δ88Sr values measured in sequential leaching fractions of sediments varied from –0.258 to 0.516‰ and were highest in the silicate fraction, followed in turn by the carbonate fraction and the exchangeable fraction. Both 87Sr/86Sr and δ88Sr of these waters are primarily controlled by the inputs of Sr in weathering products from the Bengal Plain and Sr from the Himalayan rivers (Ganges and Brahmaputra). Values of δ88Sr and Sr/Ca were higher in the Brahmaputra River than in the Ganges River, a difference we attribute to greater input from silicate weathering. The variations of δ88Sr and 87Sr/86Sr were greater in groundwater than in river waters. Mineral sorting effects and dissolution kinetics can account for the large scatter in 87Sr/86Sr and δ88Sr values. The depth profile of δ88Sr showed wide variation at shallow depths and convergence to a narrow range of about 0.31‰ at depths greater than 70 m, which reflects more complete equilibration of chemical interactions between groundwater and ambient sediments owing to the longer residence time of deeper groundwater. We found that δ88Sr values in the groundwater of Bangladesh were almost identical to those of river water from the lower Meghna River downstream of its confluence with the Ganges–Brahmaputra river system, thus confirming that the δ88Sr composition of the groundwater discharge to the Bay of Bengal is very similar to that of the river discharge.

The impact of the proposed rubber dam facilitated surface water irrigation on adjacent groundwater at Chapai Nawabganj district, Bangladesh

The dry season irrigation primarily depends on groundwater in Bangladesh. The over-abstraction, along with decreasing recharge, is depleting the groundwater resource across the country. Consequently, the government of Bangladesh is planning to switch from groundwater to surface water irrigation. In line with this, Bangladesh Water Development Board has proposed to construct a rubber dam on the Mohananda river at the Chapai Nawabganj district. This work investigated the impact of the proposed reservoir facilitated surface water irrigation on the adjacent groundwater in the study area. A coupled river–groundwater modeling technique was used to predict the long-term groundwater condition. Results showed that the groundwater lowering rate reduced to 50 mm/year inside the irrigation zone compared to 87 mm/year outside the zone. Also, the augmented surface water irrigation raised the groundwater over an area of 141 km2 and 242 km2 in 2029 relative to the base condition of 2013 and existing irrigation practice if continued, respectively. Besides, the raised groundwater resulted in a higher discharge from the aquifer to the river. The study concludes that increased surface water irrigation successfully lowered the groundwater declination rate, especially in the surface water irrigation zone.