Metal contents in the groundwater of Sahebgunj district, Jharkhand, India, with special reference to arsenic

Quality and Health Risk Assessment of Groundwaters in the Protected Area of Tisa River Basin

This study was conducted in order to assess the chemistry (41 metalloids and heavy metals and 16 physico-chemical indicators) of groundwater sampled from the protected area of the Tisa River Basin during the months of 2021. Pollution indices were used in order to determine the potential metal pollution level. Consequently, a non-carcinogenic risk assessment of metal through the ingestion of water was done. The results indicated general contamination with ammonium, chloride, iron, and manganese. The samples were rich in Cu, Mg, and Pb, but lower than the maximum limits. Significant correlations were noticed between Al-Fe, Mn-Fe, Mn-Ni, and Cr-Zn, as well as the metal content and pollution index scores. The metal pollution indices indicated three pollution levels (low, medium, and high) based on the metal content and standards regarding the water quality used for drinking purposes. The pollution indices scores ranged from 1.52-41.2. A human health risk assessment indicated no potential non-carcinogenic risk for the studied metals through the consumption of groundwater. The results of three different tools (chronic daily intake, hazard quotient, and hazard index) were below the critical value, except for the aluminium in two samples. This study is one of the first attempts to evaluate the quality of groundwater sources associated with the human health risks of the studied metals from the Tisa River Basin protected area. Based on this research, strategies for managing and controlling the risks can be developed.

Microbial and plant-assisted heavy metal remediation in aquatic ecosystems: a comprehensive review

Heavy metal (HM) pollution in aquatic ecosystems has an adverse effect on both aquatic life forms as well as terrestrial living beings, including humans. Since HMs are recalcitrant, they accumulate in the environment and are subsequently biomagnified through the food chain. Conventional physical and chemical methods used to remove the HMs from aquatic habitats are usually expensive, slow, non-environment friendly, and mostly inefficient. On the contrary, phytoremediation and microbe-assisted remediation technologies have attracted immense attention in recent years and offer a better solution to the problem. These newly emerged remediation technologies are eco-friendly, efficient and cost-effective. Both phytoremediation and microbe-assisted remediation technologies adopt different mechanisms for HM bioremediation in aquatic ecosystems. Recent advancement of molecular tools has contributed significantly to better understand the mechanisms of metal adsorption, translocation, sequestration, and tolerance in plants and microbes. Albeit immense possibilities to use such bioremediation as a successful environmental clean-up technology, it is yet to be successfully implemented in the field conditions. This review article comprehensively discusses HM accumulation in Indian aquatic environments. Furthermore, it describes the effect of HMs accumulation in the aquatic environment and the role of phytoremediation as well as microbe-assisted remediation in mitigation of the HM toxicity. Finally, the review concludes with a note on the challenges, opportunities and future directions for bioremediation in the aquatic ecosystems.

Distributions of arsenic and other heavy metals, and health risk assessments for groundwater in the Guanzhong Plain region of China

The aim of this study was to evaluate the quality of shallow groundwater and deep groundwater in the Guanzhong Plain region of China, as well as the related health risk to humans. In total, 130 groundwater samples were collected comprising 116 from shallow groundwater (dug wells) and 14 from deep groundwater (drilled wells). The water samples were analyzed to determine the levels of As and 12 other heavy metals (Al, Cd, Mn, Cr, V, Fe, Ni, Cu, Zn, Co, Pb, and Mo). The results showed that the concentrations of As and other heavy metals in the deep groundwater samples were lower than the safe limits, but the Cr concentrations in some shallow groundwater samples exceeded the safe limits. The heavy metal pollution index and heavy metal evaluation index both showed that As and other heavy metals were pollutants at low levels in all of the shallow and deep groundwater sample. Health risk assessments showed that the deep groundwater samples had no associated non-carcinogenic health risks, whereas the shallow groundwater samples had non-carcinogenic health risks due to contamination with Cr and As. Some shallow groundwater samples had associated carcinogenic health risks due to contamination with Cr and As, whereas the deep groundwater samples only had carcinogenic health risks because of contamination with Cr. These results suggest that local residents and government departments should be made aware of Cr and As pollution in shallow groundwater.

Arsenic enrichment in groundwater and associated health risk in Bari doab region of Indus basin, Punjab, India

Contaminated groundwater is considered as one of the most important pathways of human exposure to the geogenic contaminants. Present study has been conducted in a part of Indus basin to investigate the presence and spatial distribution of arsenic (As) and other trace metals in groundwater. The As concentration varies from bdl-255.6 μg/L and 24.6% of the 73 collected groundwater samples have As above world health organization (WHO) guideline of 10 μg/L. High concentration of As is found along the newer alluvium of Ravi River. As is found with high bicarbonate (HCO₃^-) and Iron (Fe) and low nitrate (NO₃^-) indicating reductive dissolution of Fe bearing minerals. However, silicate weathering along with high sulphate (SO₄²) and positive oxidation-reduction potential (ORP) indicates mixed redox conditions. Weathering of minerals along with other major hydrogeochemical process are responsible for composition of groundwater. With 31.5% of the samples, sodium bicarbonate (Na-HCO₃) is the major water facies followed by magnesium bicarbonate (Mg-HCO₃) in 30% of samples. As, Fe and other trace metals including copper (Cu), cadmium (Cd), chromium (Cr), zinc (Zn) were used to calculate the health risk for children and adults in the region. Out of 73 samples, 58% has high Fe, 32.8% has high Zn, and 4.1% has high Cd which are above the prescribed limits of WHO guidelines. Health risk of the population has been assessed using chronic dose index (CDI), hazardous quotients (HQ) and hazardous index (HI) for children and adults. The mean CDI values follows the order as Fe > Zn > Cu > As > Cr > Cd, while the HQ values indicates high As hazards for both children and adults. 43.8% of the groundwater samples have high HI for adults, however, 49.3% has high HI for children indicating higher risk for children compared to adults. A large-scale testing should be prioritized to test the wells for As and other trace metals in the study region to reduce health risks.

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

Background:

In the entire world, about 200 million populations are exposed to arsenic poisoning in groundwater. In Bihar, India about 50 million people are drinking arsenic contaminated water. This has caused various health related problems in the population like skin diseases, anemia, bronchitis, gastrointestinal problems, hormonal imbalance and cancer.

Materials and Methods:

In the present study, a total of 323 water samples were analyzed for the arsenic levels from the entire Simri village of Buxar district of Bihar and a total of 170 blood samples from the same household's subjects were collected for blood arsenic estimation through Graphite Furnace Atomic Absorption Spectrophotometer (Pinnacle 900T, Perkin Elmer, Singapore). Apart from this the correlation coefficient study between blood arsenic levels, age of the subjects, groundwater arsenic levels and depth of the handpumps were carried out.

Statistical Analysis:

Data were analyzed with statistical software (GraphPad Prism 5) and while scattered graphs were plotted through statistical software SPSS- 16.0.

Results and Conclusion:

The maximum arsenic concentration in the groundwater sample found during the study was 1929μg/L and in blood sample was 664.7μg/L. The study denotes high arsenic concentration in the drinking water of the village Simri with the highest concentration ever reported in this part of India. Furthermore, the blood samples have also been observed with high arsenic concentration in the village population which is also the highest reporting ever done in this area. The ill health of the village population also correlates our study.

Controls of paleochannels on groundwater arsenic distribution in shallow aquifers of alluvial plain in the Hetao Basin, China

Less is known about controls of sedimentary structures in groundwater As distributions in sedimentary aquifers, and quantitative description of relationship between sedimentary environment and high As groundwater (according to WHO, As>10μg/L) is a challenging issue. Three hundred and eighty-two hydrogeological borehole loggings (well depths of 50-300m) were collected and four hundred and ninety nine groundwater samples were taken to investigate controls of paleochannels on groundwater arsenic distribution in shallow aquifers of alluvial plain in the Hetao Basin. Results showed that the swing zone, formed by bursting, diversion and swing of ancient Yellow River course since the Late Pleistocene, has an obviously corresponding relationship with spatial variability of groundwater As in the Hetao Basin. "Swing Intensity Index" (S), which is firstly defined as the sum of clay-sand ratio (R) and the number of clay layers (N), can be used as the sedimentary facies symbol to establish the new recognition method for hosting high As groundwater. There is a positive correlation between the swing intensity index (S) of paleochannels and groundwater As concentrations. The swing zones of paleochannels with high S values represent hydrogeochemical characteristics of the strong reducing environment, serious evaporation, strong cation exchange, and the low infiltration recharge of surface water, which lead to enrichment of groundwater As in the shallow aquifers.

Fe-FeS2 adsorbent prepared with iron powder and pyrite by facile ball milling and its application for arsenic removal

Arsenic is one of the major pollutants and a worldwide concern because of its toxicity and chronic effects on human health. An adsorbent of Fe-FeS2 mixture for effective arsenic removal was successfully prepared by mechanical ball milling. The products before and after arsenic adsorption were characterized with scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorbent shows high arsenic removal efficiency when molar ratio of iron to pyrite is 5:5. The experimental data of As(III) adsorption are fitted well with the Langmuir isotherm model with a maximal adsorption capacity of 101.123 mg/g. And As(V) data were described perfectly by the Freundlich model with a maximal adsorption capacity of 58.341 L/mg. As(III) is partial oxidized to As(V) during the adsorption process. High arsenic uptake capability and cost-effectiveness of waste make it potentially attractive for arsenic removal.

Iron supported on bioinspired green silica for water remediation

Iron has been used previously in water decontamination, either unsupported or supported on clays, polymers, carbons or ceramics such as silica. However, the reported synthesis procedures are tedious, lengthy (involving various steps), and either utilise or produce toxic chemicals. Herein, the use of a simple, rapid, bio-inspired green synthesis method is reported to prepare, for the first time, a family of iron supported on green nanosilica materials (Fe@GN) to create new technological solutions for water remediation. In particular, Fe@GN were employed for the removal of arsenate ions as a model for potentially toxic elements in aqueous solution. Several characterization techniques were used to study the physical, structural and chemical properties of the new Fe@GN. When evaluated as an adsorption platform for the removal of arsenate ions, Fe@GN exhibited high adsorption capacity (69 mg of As per g of Fe@GN) with superior kinetics (reaching ∼35 mg As per g sorbent per hr) - threefold higher than the highest removal rates reported to date. Moreover, a method was developed to regenerate the Fe@GN allowing for a full recovery and reuse of the adsorbent in subsequent extractions; strongly highlighting the potential technological benefits of these new green materials.

Fe3O4 and MnO2 assembled on honeycomb briquette cinders (HBC) for arsenic removal from aqueous solutions

In this study, a novel composite adsorbent (HBC-Fe3O4-MnO2) was synthesized by combining honeycomb briquette cinders (HBC) with Fe3O4 and MnO2 through a co-precipitation process. The purpose was to make the best use of the oxidative property of MnO2 and the adsorptive ability of magnetic Fe3O4 for enhanced As(III) and As(V) removal from aqueous solutions. Experimental results showed that the adsorption capacity of As(III) was observed to be much higher than As(V). The maximum adsorption capacity (2.16 mg/g) was achieved for As(III) by using HBC-Fe3O4-MnO2 (3:2) as compared to HBC-Fe3O4-MnO2 (2:1) and HBC-Fe3O4-MnO2 (1:1). The experimental data of As(V) adsorption fitted well with the Langmuir isotherm model, whereas As(III) data was described perfectly by Freundlich model. The pseudo-second-order kinetic model was fitted well for the entire adsorption process of As(III) and As(V) suggesting that the adsorption is a rate-controlling step. Aqueous solution pH was found to greatly affect the adsorption behavior. Furthermore, co-ions including HCO3(-) and PO4(3-) exhibited greater influence on arsenic removal efficiency, whereas Cl(-), NO3(-), SO4(2-) were found to have negligible effects on arsenic removal. Five consecutive adsorption-regeneration cycles confirmed that the adsorbent could be reusable for successive arsenic treatment and can be used in real treatment applications.

Natural and anthropogenic factors affecting the groundwater quality in Serbia

Various chemometric techniques were used to analyze the quality of groundwater data sets. Seventeen water quality parameters: the cations Na, K, Ca, Mg, the anions Cl, SO4, NO3, HCO3 and nine trace elements Pb, As, Mn, Ni, Cu, Cd, Fe, Zn and Cr were measured at 66 different key sampling sites in ten representative areas (low land-Northern Autonomous Province of Serbia, Vojvodina and central Serbia) for the summer period of 2009. HCA grouped the sample sites into four clusters based on the similarities of the characteristics of the groundwater quality. DA showed two parameters, HCO3 and Zn, affording more than 90% correct assignments in the spatial analysis of four/three different regions in Serbia. Factor analysis was applied on the log-transformed data sets and allowed the identification of a reduced number of factors with hydrochemical meaning. The results showed severe pollution with Mn, As, NO3, Ni, Pb whereby anthropogenic origin of these contaminants was indicated. The pollution comes from both scattered point sources (industrial and urban effluent) and diffuse source agricultural activity. These samples may not be suitable for human consumption; the water quality belongs to class III/IV (contaminated). The Fe anomalies (7.1mg/L) in the water from the Vetrnica site can be attributed to natural sources, such as the dissolution of rock masses and rock fragments. The serious groundwater contamination with As (25.7-137.8 μg/L) in the area of Banat (Northern Autonomous Province of Serbia, Vojvodina) and a sample No. 9 at the Great Morava River requires urgent attention.

Arsenic occurrence and accumulation in soil and water of eastern districts of Uttar Pradesh, India

Arsenic in the soil and water of eastern districts of Uttar Pradesh (Ballia and Ghazipur) was estimated. Survey results revealed that arsenic in soil samples ranged from 5.40 to 15.43 parts per million (ppm). In water samples, it ranged from 43.75 to 620.75 parts per billion (ppb) which far exceeded the permissible limit of 10 ppb as recommended by the World Health Organization. Maximum concentration of arsenic in water was found in Haldi village of Ballia (620.75 ppb). However, mean arsenic concentration in water followed the order: Karkatpur (257.21 ppb) < Haldi (310.15 ppb) < Sohaon (346.94 ppb) < Dharmarpur (401.75 ppb). In case of soil, maximum arsenic was detected in soil of Sohaon (15.43 ppm). Mean arsenic levels in soils followed the order: Karkatpur (9.24 ppm) < Haldi (9.82 ppm) < Dharmarpur (11.32 ppm) < Sohaon (14.08 ppm). Arsenic levels were higher in soils collected from 15-30 cm depth than 0-15 cm from the soil surface.

Exposure to multiple metals from groundwater-a global crisis: geology, climate change, health effects, testing, and mitigation

This paper presents an overview of the global extent of naturally occurring toxic metals in groundwater. Adverse health effects attributed to the toxic metals most commonly found in groundwater are reviewed, as well as chemical, biochemical, and physiological interactions between these metals. Synergistic and antagonistic effects that have been reported between the toxic metals found in groundwater and the dietary trace elements are highlighted, and common behavioural, cultural, and dietary practices that are likely to significantly modify health risks due to use of metal-contaminated groundwater are reviewed. Methods for analytical testing of samples containing multiple metals are discussed, with special attention to analytical interferences between metals and reagents. An overview is presented of approaches to providing safe water when groundwater contains multiple metallic toxins.

Chemometrics in assessment of seasonal variation of water quality in fresh water systems

The chemometric techniques were applied for evaluation of the seasonal variation of water qualities at 17 stations along a stretch of the Bagmati river of Nepal for 23 water quality parameters measured during 1999-2003. The application of discriminant analysis confirmed the classification of the water quality measurements into three seasons: pre-monsoon, monsoon, and post-monsoon affording 93.8% correct classification. Factor analysis and box-whisker plots facilitated to investigate the seasonal variation of water quality and the pattern of pollution sources. Application of FA revealed that the influence of water quality parameters changes from season to season. A parameter that is most important in contributing to water quality variation for one season may not be important for another season. Comparison of the discriminant analysis and factor analysis helped to identify the most important water quality parameters, as water temperature, DO, EC, COD, CL, Ca, alkalinity, PO(4)P, and TP, that are most important for seasonal variation and play a significant role in establishment of water quality control strategy.

Groundwater arsenic contamination in Brahmaputra river basin: a water quality assessment in Golaghat (Assam), India

Distribution of arsenic (As) and its compound and related toxicology are serious concerns nowadays. Millions of individuals worldwide are suffering from arsenic toxic effect due to drinking of As-contaminated groundwater. The Bengal delta plain, which is formed by the Ganga-Padma-Meghna-Brahmaputra river basin, covering several districts of West Bengal, India, and Bangladesh is considered as the worst As-affected alluvial basin. The present study was carried out to examine As contamination in the state of Assam, an adjoining region of the West Bengal and Bangladesh borders. Two hundred twenty-two groundwater samples were collected from shallow and deep tubewells of six blocks of Golaghat district (Assam). Along with total As, examination of concentration levels of other key parameters, viz., Fe, Mn, Ca, Na, K, and Mg with pH, total hardness, and SO[Formula: see text], was also carried out. In respect to the permissible limit formulated by the World Health Organization (WHO; As 0.01 ppm, Fe 1.0 ppm, and Mn 0.3 ppm for potable water), the present study showed that out of the 222 groundwater samples, 67%, 76.4%, and 28.5% were found contaminated with higher metal contents (for total As, Fe, and Mn, respectively). The most badly affected area was the Gamariguri block, where 100% of the samples had As and Fe concentrations above the WHO drinking water guideline values. In this block, the highest As and Fe concentrations were recorded 0.128 and 5.9 ppm, respectively. Tubewell water of depth 180±10 ft found to be more contaminated by As and Fe with 78% and 83% of the samples were tainted with higher concentration of such toxic metals, respectively. A strong significant correlation was observed between As and Fe (0.697 at p<0.01), suggesting a possible reductive dissolution of As-Fe-bearing minerals for the mobilization of As in the groundwater of the region.

Seasonal variations of lead, arsenic, cadmium and aluminium contamination of groundwater in Dhemaji district, Assam, India

Seasonal variations in the concentrations of groundwater with respect to arsenic, lead, cadmium and aluminium has been studied in Dhemaji district of Assam, India. The water samples were collected from 20 different sites in both dry and wet seasons. The metals were analysed by using atomic absorption spectrometer, Perkin Elmer AAnalyst 200 model. The concentrations of aluminium, lead and cadmium in groundwater were found to be significantly elevated. High concentrations of all the metals were recorded in the dry season than in the wet season. Univariate statistics along with skewness, kurtosis and confidence limit have been calculated for both the seasons to test the distribution normality for each metal. Statistical analyses of the data reveal non-uniform distribution of the metals in the area. The metal contamination of groundwater in the district follows the trend Al>Pb>Cd>As in both the seasons.

Targeting arsenic-safe aquifers for drinking water supplies

At present, 70 countries worldwide are affected by groundwater contamination by arsenic (As) released from predominantly geogenic sources. Consequently, the As problem is becoming a global issue. The option to target As-safe aquifers, which uses geological, geochemical, hydrogeological, morphological and climatic similarities to delimit As-safe aquifers, appears as a sustainable mitigation option. Two pilot areas, Meghna Flood Plain in Matlab Upazila, representative of Bengal Delta in Bangladesh, and Río Dulce Alluvial Cone, representing a typical aquifer setting in the Chaco-Pampean Plain in Argentina groundwater As occurrence, were compared. In rural Bangladesh, As removal techniques have been provided to the population, but with low social acceptance. In contrast, "targeting As-safe aquifers" was socially accepted in Bangladesh, where sediment color could be used to identify As-safe aquifer zones and to install safe wells. The investigation in Argentina is more complex because of very different conditions and sources of As. Targeting As-safe aquifers could be a sustainable option for many rural areas and isolated peri-urban areas.

Biosorption studies on powder of stem of Acacia nilotica: Removal of arsenic from surface water

In present study a biomass derived from the stem of Acacia nilotica has been investigated to remove As ions from surface water samples of different origins (lake, canal and river). The effects of various parameters viz. pH, biosorbent dosage, contact time and temperature on the biosorption processes were systematically studied. Experimental data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. It was observed that As biosorption best fitted to the Langmuir and Freundlich isotherms. The mean sorption energy (E) calculated from D-R model, indicated physico-chemical biosorption. Study of thermodynamic parameters revealed the endothermic, spontaneous and feasible nature of biosorption process. The pseudo-second-order rate equation described better the kinetics of As biosorption with good correlation coefficients than pseudo-first-order equation. The biomass of A. nilotica was found to be effective for the removal of As with 95% sorption efficiency at a concentration of <200 microg/L of As solution, and thus uptake capacity is 50.8 mg As/g of biomass. The A. nilotica biomass could be used as a low-cost biosorbent for As ion removal.

Removal of arsenic from contaminated groundwater by solar-driven membrane distillation

Experimental investigations were carried out on removal of arsenic from contaminated groundwater by employing a new flat-sheet cross flow membrane module fitted with a hydrophobic polyvinylidenefluoride (PVDF) microfiltration membrane. The new design of the solar-driven membrane module in direct contact membrane distillation (DCMD) configuration successfully produced almost 100 per cent arsenic-free water from contaminated groundwater in a largely fouling-free operation while permitting high fluxes under reduced temperature polarization. For a feed flow rate of 0.120 m3/h, the 0.13 microm PVDF membrane yielded a high flux of 74 kg/(m2h) at a feed water temperature of 40 degrees C and, 95 kg/m2h at a feed water temperature of 60 degrees C. The encouraging results show that the design could be effectively exploited in the vast arsenic-affected rural areas of South-East Asian countries blessed with abundant sunlight particularly during the critical dry season.

Arsenic contamination in groundwater in the Southeast Asia region

The adverse impact of groundwater contaminated with arsenic (As) on humans has been reported worldwide, particularly in Asian countries. In this study, we present an overview of the As crisis in the Southeast Asian region where groundwater is contaminated with naturally occurring As and where contamination has become more widespread in recent years. In this region more than 100 million people are estimated to be at risk from groundwater As contamination, and some 700,000 people are known so far to have been affected by As-related diseases. Despite investments exceeding many millions of dollars, there are still substantial knowledge gaps about the prevalence and impact of As, notably in its epidemiology, temporal variations, social factors, patient identification, treatment, etc. Arsenic-affected people in the affected regions also face serious social problems. Of major concern is the fact that many researchers from different countries have been conducting research in SE Asia region but with a lack of coordination, thus duplicating their work. There is an urgent need to coordinate these various studies to ensure better delivery of research outcomes. Further research is needed to improve field testing and monitoring of drinking water sources, and to develop new treatments for chronic As toxicity and new sources of safe drinking water.

Soil washing of As-contaminated stream sediments in the vicinity of an abandoned mine in Korea

A soil washing process was applied to remediate arsenic (As)-contaminated stream sediments around an abandoned mine in Goro, Korea. Laboratory scale soil washing experiments for As-contaminated stream sediments were performed under various washing conditions in order to maximize As removal efficiency. Stream sediments were taken from two sites (S1 and S5) along the main stream connected to an abandoned mine. Stream sediments at the two sites were divided into two groups (>or=0.35 and <0.35 mm in diameter), giving four types of sediments, which were thereupon used for soil washing experiments. The results of soil washing experiments involving various pH conditions suggested that As removal efficiency is very high in both strongly acidic and basic solutions (pH 1 and 13), regardless of sediment type. Removal efficiencies for fine sediments from S1 and S5 were >95% after 1 h of washing with 0.2 M citric acid (C(6)H(8)O(7)). When using 0.2 M citric acid mixed with 0.1 M potassium phosphate (KH(2)PO(4)), the As removal efficiency increased to 100%. When recycled washing solution was applied, As removal efficiency was maintained at a level greater than 70%, even after eight recycling events. This suggests that the recycling of washing solution could be successfully applied as a means of decreasing the cost of the washing process. Results from the experiments suggest that soil washing is a potentially useful process for the remediation of As-contaminated stream sediments around abandoned mines.

Arsenic groundwater contamination and its health effects in the state of Uttar Pradesh (UP) in upper and middle Ganga plain, India: a severe danger

This communication presents results of our 2-year survey on groundwater arsenic contamination in three districts Ballia, Varanasi and Gazipur of Uttar Pradesh (UP) in the upper and middle Ganga plain, India. Analyses of 4,780 tubewell water samples revealed that arsenic concentrations in 46.5% exceeded 10 microg/L, in 26.7%, 50 microg/L and in 10% 300 microg/L limits. Arsenic concentrations up to 3,192 microg//L were observed. The age of tubewells (n=1,881) ranged from less than a year to 32 years, with an average of 6.5 years. Our study shows that older tubewells had a greater chance of contamination. Depth of tubewells (n=3,810) varied from 6 to 60.5 m with a mean of 25.75 m. A detailed study in three administrative units within Ballia district, i.e. block, Gram Panchayet, and village was carried out to assess the magnitude of the contamination. Before our survey the affected villagers were not aware that they were suffering from arsenical toxicity through contaminated drinking water. A preliminary clinical examination in 11 affected villages (10 from Ballia and 1 from Gazipur district) revealed typical arsenical skin lesions ranging from melanosis, keratosis to Bowens (suspected). Out of 989 villagers (691 adults, and 298 children) screened, 137 (19.8%) of the adults and 17 (5.7%) of the children were diagnosed to have typical arsenical skin lesions. Arsenical neuropathy and adverse obstetric outcome were also observed, indicating severity of exposure. The range of arsenic concentrations in hair, nail and urine was 137-10,900, 764-19,700 microg/kg, and 23-4,030 microg/L, respectively. The urine, hair and nail concentrations of arsenic correlated significantly (r=0.76, 0.61, and 0.55, respectively) with drinking water arsenic concentrations. The similarity to previous studies on arsenic contamination in West Bengal, Bihar and Bangladesh indicates that people from a significant part of the surveyed areas in UP are suffering and this will spread unless drives to raise awareness of arsenic toxicity are undertaken and an arsenic safe water supply is immediately introduced.

Laboratory based approaches for arsenic remediation from contaminated water: recent developments

Arsenic contamination in water has posed severe health problems around the world. In spite of the availability of some conventional techniques for arsenic removal from contaminated water, development of new laboratory based techniques along with enhancement and cost reduction of conventional techniques are essential for the benefit of common people. This paper provides an overview of the arsenic issue in water such as modes of contamination of ground water as well as surface water by arsenic, its metabolism and health impacts, factors influencing arsenic poisoning, fundamentals of arsenic poisoning mechanism and world scenario of arsenic poisoning. It discusses and compares the conventional laboratory based techniques, like precipitation with alum, iron, Fe/Mn, lime softening, reverse osmosis, electro dialysis, ion exchanges, adsorption on activated alumina/carbon, etc., for arsenic removal from contaminated water. It also discusses the best available techniques and mentions the cost comparison among these techniques too. Recent developments in the research on the laboratory based arsenic removal techniques, like improvement of conventional techniques and advances in removal technology along with its scopes and limitations have also been reviewed.