School Of Environment And Earth Sciences

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Author: search.filters.author.Chaudhari, Umakant

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    Co-occurrence of geogenic uranium and fluoride in a semiarid belt of the Punjab plains, India
    (Elsevier B.V., 2023-10-05T00:00:00) Chaudhari, Umakant; Mehta, Madhu; Sahoo, Prafulla Kumar; Mittal, Sunil; Tiwari, Raghavendra P.
    The inordinate presence of uranium (U) and fluoride (F?) in shallow aquifers of arid/semi-arid regions in northern India has raised a serious health concern; the Muktsar district of Punjab is one such example. In the present study, a total of 38 groundwater samples (17 from <100 ft (very shallow; VSL), 21 from >100 to 180 ft (shallow; SL)) were collected from this district to understand the current health risk associated with U and F? and the major factors/processes influencing these contaminants. Groundwater in the study area is mostly alkaline and oxic in nature. The concentration of U ranged from 18.5 ?g/L to 456 ?g/L exceeding the WHO permissible limit (>30 ?g/L) in 93 and 100% samples from VSL and SL respectively, while F? concentration (ranged from 0.3 to 14.4 mg/L) above the limit (>1.5 mg/L) were found in 75 and 57% samples from VSL and SL respectively. As per the depth-wise distribution of U and F?, there is no significant difference between VSL and SL samples, with a few exceptions. Spearman rank correlation (?) shows a significant positive correlation (p-value < 0.05) between U and F? (? = 0.5), and U with total dissolved solid (TDS) (? = 0.5), salinity (? = 0.6), and bicarbonate (HCO3?) (? = 0.7) and a positive association of F? with TDS (? = 0.3), salinity (? = 0.3), and HCO3? (? = 0.3), indicating these parameters are responsible for the co-occurrence of U and F?. Moreover, this geochemical signature is attributed to their geogenic origin. Uranium speciation data show that UO2(CO3)22? and UO2(CO3)34? are dominant species, while F? predominantly occurs as F? species. The regions with high concentration of U and F? in groundwater primarily have mixed type species (Na�HCO3 and NaCl type). Geochemical modelling revealed that the precipitation of calcite, dolomite, and aragonite is favourable for mobility of F? in groundwater. The hazard quotient (HQ) of F? for adults and children exceeds 1 in 57.8% and 65.7% of samples, respectively, while in case of U, 94.7% and 100% samples exceed 1, respectively, indicating the latter is having greater health impact on local people. The current data indicated an urgent demand to develop low-cost and effective remedial techniques to manage groundwater contamination in this region. � 2023
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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.