School Of Environment And Earth Sciences

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Subject: search.filters.subject.Geogenic contamination

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    Geogenic enrichment of fluoride in groundwater of hard rock aquifer in fluorosis prevalent area of Balangir district, Odisha, India
    (Elsevier B.V., 2022-08-28T00:00:00) Sahoo, Prafulla Kumar; Ray, Subhransu Bhusan; Kerketta, Anjali; Behera, Pintu; Neogi, Gautam; Sahoo, Himadri Bhusan
    Hydrogeochemical characterization of groundwater has been carried out in a hard rock aquifer from Balangir district, a fluorosis-affected area of Odisha, India with the aim of understanding the sources and processes controlling fluoride (F?) enrichment. A total of 37 groundwater (tube wells) and 7 surface water (pond) samples were collected during the pre-monsoon period. Groundwaters are mostly categorized as moderate to very hard water types with alkaline nature. The enhanced Na+ and HCO3? concentration in groundwater is mostly a result of silicate weathering. The F? concentration in groundwater ranged from 0.4 to 4.29 mg/l, with 38% of samples exceeded the drinking water limit (1.5 mg/l; as prescribed by the World Health Organization, 2011), in contrast to very low F? (<0.9 mg/l) in surface water. High F? concentrations in underlying granitic bedrocks (up to 700 mg/kg), which spatially corresponds to F? rich groundwater, suggest that lithological composition is the main control of F?. Fluoride-rich waters are mostly Na�HCO3 type, followed by mixed Na�Ca�HCO3 (Cl) type with Na+/Ca2+ ratio >1. The significant positive correlations of F? with Na+, HCO3?, and pH indicate that the weathering of sodium-rich silicate minerals and increase of pH mobilizes F? ion. Geochemical modeling indicates that the activity of F? in groundwater increased by precipitation of calcite, dolomite, and aragonite. Fluoride risk assessment indicates that 38% of groundwater samples can cause a high prevalence of dental fluorosis with children being at greater risk than adults. Henceforth, it is advisable to treat this contaminated groundwater before consumption or provide alternative drinking water to avoid further fluorosis risks in the concerned area. � 2022 Elsevier B.V.
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    Meta-analysis of uranium contamination in groundwater of the alluvial plains of Punjab, northwest India: Status, health risk, and hydrogeochemical processes
    (Elsevier B.V., 2021-11-23T00:00:00) Sahoo, Prafulla Kumar; Virk, Hardev Singh; Powell, Mike A.; Kumar, Ravishankar; Pattanaik, Jitendra Kumar; Salom�o, Gabriel Negreiros; Mittal, Sunil; Chouhan, Lokesh; Nandabalan, Yogalakshmi Kadapakkam; Tiwari, Raghavendra Prasad
    Despite numerous studies, there are many knowledge gaps in our understanding of uranium (U) contamination in the alluvial aquifers of Punjab, India. In this study, a large hydrogeochemical dataset was compiled to better understand the major factors controlling the mobility and enrichment of uranium (U) in this groundwater system. The results showed that shallow groundwaters (<60 m) are more contaminated with U than from deeper depths (>60 m). This effect was predominant in the Southwest districts of the Malwa, facing significant risk due to chemical toxicity of U. Groundwaters are mostly oxidizing and alkaline (median pH: 7.25 to 7.33) in nature. Spearman correlation analysis showed that U concentrations are more closely related to total dissolved solids (TDS), salinity, Na, K, HCO3?, NO3? Cl?, and F? in shallow water than deep water, but TDS and salinity remained highly correlated (U-TDS: ? = 0.5 to 0.6; U-salinity: ? = 0.5). This correlation suggests that the salt effect due to high competition between ions is the principal cause of U mobilization. This effect is evident when the U level increased with increasing mixed water species (Na-Cl, Mg-Cl, and Na-HCO3). Speciation data showed that the most dominant U species are Ca2UO2(CO3)2? and CaUO2(CO3)3?, which are responsible for the U mobility. Based on the field parameters, TDS along with pH and oxidation-reduction potential (ORP) were better fitted to U concentration above the WHO guideline value (30 ?g.L?1), thus this combination could be used as a quick indicator of U contamination. The strong positive correlation of U with F? (? = 0.5) in shallow waters indicates that their primary source is geogenic, while anthropogenic factors such as canal irrigation, groundwater table decline, and use of agrochemicals (mainly nitrate fertilizers) as well as climate-related factors i.e., high evaporation under arid/semi-arid climatic conditions, which result in higher redox and TDS/salinity levels, may greatly affect enrichment of U. The geochemical rationale of this study will provide Science-based-policy implications for U health risk assessment in this region and further extrapolate these findings to other arid/semi-arid areas worldwide. � 2021 Elsevier B.V.