Mitigation and Remedy of Groundwater Arsenic Menace in India

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Mitigation and Remedy of Groundwater Arsenic Menace in India : A Vision Document(iv)(v)(vi)Public Health Engineering Department, Government of West Bengal has establisheddistrict level chemical laboratories for detecting arsenic content in groundwater. Thosechemical laboratories have been equipped with equipments to trace elements other thanarsenic;A number of surface water based schemes have been put into operation in places,wherever they are feasible, with provision of chemical treatment;Arsenic removal plants, based on various treatment technologies to treat arsenic contaminated groundwater, have been installed in many places and put into operation toprovide potable water to the affected populace where there were no access of othersources of potable water supply;(vii) Arsenic free deeper aquifers and wells explored and constructed by CGWB have beenput to use by the state agencies for public water supply;(viii)(ix)Arsenic content in food chains and their effect on ingestion have been analyzed.However, what forms of arsenic, organic or inorganic, are present in groundwater andthe degree of consequential impact of arsenic containing food chains on human health isyet to be established;Many R & D studies focusing towards understanding source and causes, geochemicalprocesses, extent of mobilization, social and health hazards, impact on food chains, etc.have been initiated.In addition to the above steps taken by the Government, a number of non-governmentalorganizations, academic and R & D organizations have come forward to rescue the affectedpopulace, in supply of potable water through installation of a number of arsenic-free hand pumpsand treatment devices under the community participation. Despite such considerable steps andmeasures, the task of ensuring potable water supply in many areas has remained a big questionbecause of: (i) lack of proper coordination, (ii) poor operation and maintenance of arsenicremoval devices, and (iii) unsatisfactory performance of the arsenic removal filters used in thedevices.The source of irrigation in most of the arsenic affected areas is groundwater fromshallow aquifer within 100 m bgl. In the absence of alternate source of arsenic free irrigationwater, rural people continue to tap arseniferous aquifer resulting in further aggravation of theproblem in different forms, such as, mobilization of arseniferous groundwater to freshwaterzones, spreading of the sources by the cycling process of water and use of fertilizers andpesticides, transport through food chains, etc. The crux in the management of the whole problemhas boiled down to single point as to how to ensure arsenic free irrigation water into the arsenicaffected areas. Wherein the use and reuse of contaminated groundwater, on one hand, have thethreat of arsenic contamination through food chains; on the other hand, infiltration of arseniccontaminated water, together with residual of fertilizers and pesticides, may provoke contaminationNIH & CGWB 59
Mitigation and Remediation Update from West Bengal and Bihar : Studies and Projects Initiatedof vadose zone, and mobilization of arsenic in the freshwater zones. Ensuring supply of potablewater alone, thus, seems to be inadequate to attain sustainability in terms of resolving the arsenicmenace. It is, therefore, necessary to consider a framework of problem-solving curriculum linkingone issue to another, one's favoring and posing condition to another, and resolve thosesystematically in a judicious manner to achieve the target of human-land-water resources management in the arsenic affected areas.4.1.2 Findings of initiated R & D studiesA number of research studies have been pursued to investigate extent, mobilizationprocess, geochemistry, hydro-geological properties and processes by different organizations.Findings of various research studies have broadly been discussed in chapter-3. The CentralGround Water Board-Eastern Region (CGWB-ER), in addition to the above aspects, undertooktasks to identify potential arsenic safe zones aquifer. Findings of CGWB-ER are given below:(i)(ii)(iii)(iv)(v)(vi)Arseniferous aquifers are mainly observed within the shallow depth (within 100 mbelow ground level), while the deeper aquifer (>100 m bgl) in the same area is foundfree from arsenic. The shallow and the deeper aquifers are separated by a thickimpervious clay layer and the thickness is above 10 m. The deeper aquifer is capable toyield 5 to 20 lps of water. It is further observed that when the deeper aquifer is pumpedcreating a drawdown of 6 m, there is not much impact on the overlain arseniccontaminated zone.Groundwater in the arsenic affected area is characterized by high iron, calcium, magnesium, bicarbonate with low chloride, sulphate, fluoride and sodium.Geologically, the arsenic affected areas are the parts of the Ganga-Bhagirathi deltacomprising succession of thick Quaternary sediments. The arseniferous tract is restrictedin the upper delta plain within shallow depth, which is mainly built up of sedimentsdeposited by meandering streams and levees composed of sands of various grades, silt,clay and their admixtures.The groundwater mostly occurs in thick zone of saturation within the unconsolidatedalluvial sediments in the affected areas; and the aquifers are made up of sands of various grades. Groundwater occurs generally under unconfined hydro-geologic conditions.The arsenic groundwater contamination is attributed to the geogenic origin, and thesource of arsenic in localized patches is due to presence of Arsenopyrite in clay andsand. Arsenic concentration is more in clay than in sand.In arsenic affected areas, all tube wells harnessing shallow aquifers do not yield arseniccontaminated water. Some are arsenic affected and some others are free from suchcontamination.60NIH & CGWB
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ACKNOWLEDGEMENTThe Government of In
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nearly 33 villages in 4 districts i
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(iii) Whether ex-situ removal techn
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6.4 Experiences during Arsenic Remo
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List of FiguresFigure no. Figure ca
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List of TablesTable no. Table Capti
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Mitigation and Remedy of Groundwate
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Mitigation and Remedy of Groundwater Arsenic Menace in India

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