School Of Environment And Earth Sciences

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    Quality assessment of surface water and groundwater giving emphasis on water quality index and irrigational indicators in the southeastern part of Manipur Valley, north-east India
    (John Wiley and Sons Ltd, 2021-12-21T00:00:00) Thokchom, Laxmi; Kshetrimayum, Krishnakanta Singh
    Water quality index (WQI) and irrigational indices for surface water and groundwater in the southeastern part of Manipur Valley in north-east India has been examined. The water samples were collected during the pre-monsoon season in the year 2016. Geologically, the Manipur Valley occurs as an intermontane piedmont-alluvial plain filled with Quaternary alluvium of fluvio-lacustrine origin. The basic chemical parameters of pH, total dissolved solids, electrical conductivity, total hardness, Cl?, HCO3?, Na+, Ca2+, Mg2+, Fe, Mn, and Zn were considered for computing water quality index for drinking water. Irrigational indices such as sodium absorption ratio, sodium percentage, Kelly's index, magnesium hazard, and residual sodium carbonate were calculated for determining the suitability for irrigational use. WQI, SAR, %Na+, KI, MH, RSC suggest that majority of the water samples are suitable for drinking and irrigational uses. They exhibit positive relations among them suggesting that these parameters are dependent over one another. About 20% of the piedmont zone groundwater are unsuitable for both drinking and agricultural purposes. The encrustation of gypsum, halite, and evaporite into the Disang shales enhances the dissolution process of ions such as Cl?, Na+, Ca2+, Mg2+ in the piedmont water leading to quality deterioration. Gibb's plots suggest that the chemical origin of water dominates with rock-weathering process, while hydrochemical facies evolved from the initial stage to intermediate stage. Therefore, proper integrated management and development of water resources is necessary for the effective utilization water resources particularly around the piedmont zone. � 2021 John Wiley & Sons Ltd.
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    Distribution of rare earth elements and stable isotopic constituents along the groundwater flow paths in the Quaternary deposits of Imphal valley in north-east India
    (John Wiley and Sons Ltd, 2021-09-22T00:00:00) Singh, Laishram Premananda; Kshetrimayum, Krishnakanta Singh
    Groundwater samples collected from three flow paths (the western, central, and eastern flows) in the shallow aquifers of the Imphal valley of north-east India were examined to study the variation in hydrochemical and rare earth element (REE) characteristics along these flow paths. Each flow path covers a length of around 45 km towards the down gradient. In the western flow, the hydrochemical facies evolved from Na-Cl-Ca to Ca-Na-Mg-Cl-HCO3; in the central flow, it varies from Ca-Mg-Na-Cl to Na-Ca-Cl-HCO3 and in the eastern flow, it changes from Na-Cl to Ca-Mg-HCO3 indicating the evolution of saline water type in the piedmont zone to fresh water type towards the discharge zones around the Loktak Lake. The REE concentration varies along the flow path as the total light REE (LREE) is more enriched than total heavy REE (HREE) in the western and central flows, while LREE is less than HREE in the eastern flow. North American Shale Composite (NASC)-normalized REE patterns in these flow types show significant convex-up NASC-normalized patterns with depleted LREEs. The redox condition in the flow paths is controlled by redox-sensitive elements such as Eh, pH, Fe, Mn, U, Er, Gd, and Nd which vary relatively along with these flows. REE fractionation depicted by (Er/Nd)SN ratios are high around the upgradient and decrease along the down gradient towards Loktak Lake. The isotopic constituents (?18O and ?D) exhibit fluctuations in their ratios along the groundwater flow paths. The residual hill and piedmont zones are characterized by depleted isotopic composition while the alluvial and flood plains show enriched isotopic composition. Thus, the present study elucidates the behavioural change in major hydrochemical parameters including REE and isotopic constituents, along with the groundwater flow, which will provide a holistic view in understanding the evolution of groundwater in terms of its quality, quantity, and origin in the study area. � 2021 John Wiley & Sons Ltd.
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    Arsenic Contamination in Groundwater and Its Removal Strategies with Special Emphasis on Nano Zerovalent Iron
    (wiley, 2022-12-02T00:00:00) Thakur, Shivani; Singh, Harminder; Chaudhari, Umakant; Mittal, Sunil; Sahoo, Prafulla Kumar
    An occurrence of arsenic (As) in an aquatic ecosystem is a major concern because of its very toxic and carcinogenic nature. Groundwater arsenic pollution has been reported globally, notably along the large Indo-Gangetic flood plain and some major rivers of South Asia and South American nations. It comes in water both via natural and anthropogenic sources. Major processes that trigger the release of As in groundwater include reductive dissolution of Fe-oxyhydroxides, sulfide oxidation, and alkali desorption. Microbial metabolisms of arsenic also play a crucial role in its mobilization in aquifers. Ions such as HCO 3 ? and PO 4 3? also help in triggering arsenic mobility in water. Different methods are developed for As removal from water such as precipitation, coagulation, ion exchange, and membrane filtration, but none of the methods are as effective as nanomaterials. With the advancement in a study in nanotechnology during the past few years, an increase in usage of different nanomaterials as adsorbents for arsenic removal has also been observed. Among these, nano zerovalent iron (nZVI) has been proved quite effective for arsenic removal from the water by the adsorption technique. The nZVI has high reactivity, good efficiency, and fast action for As removal, and a low impact on the environment. Further, intensive research is going on to alter the properties of nZVI following specific applications as per the requirements. This chapter presents an overview of several geochemical processes aiding in As mobility from the aquifer sediments into groundwater, briefly describing its distribution pattern across global groundwater systems. It also aims to provide an overview of the effectiveness of different iron-based nanoparticles with particular reference to nZVI for the removal of different species of Arsenic from water. � 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd. All rights reserved.