NAGENDRA KUMAR P V
Articles written in Journal of Earth System Science
Volume 129 All articles Published: 9 October 2020 Article ID 0205 Research article
TIRUMALESH KEESARI ANNDASANKAR ROY DIKSHA PANT UDAY KUMAR SINHA NAGENDRA KUMAR P V L VAIKUNTA RAO
This paper elaborates the hydrochemical and environmental isotope ($\delta^{2}$H and $\delta^{18}$O) inferences obtained from Uddanam region, Andhra Pradesh, India. Groundwater samples collected during pre-monsoon (June 2019) showed that the quality is fresh (EC < 1539 $\mu$S/cm) and contaminants like fluoride (<1.6 mg/L) and nitrate (<49 mg/L) are present within permissible limits. The composite water quality indices for drinking (DWQI: 14.1–92.5) and irrigation (IWQI: 2.8–20.2) are found to be satisfactory. The major water types are found to be Ca–Na–HCO$_{3}$, Na–Ca–HCO$_{3}$, Na–Mg–HCO$_{3}$–Cl, Ca–Mg–HCO$_{3}$–Cl and Na–HCO$_{3}$. Three geochemical pathways are found signifying evaporite dissolution, contribution of silicate mineral weathering and base-exchange process, which is supported by estimated chloro-alkaline indices (CAI-1: −4.3 to −0.2, CAI-2: −1.03 to −0.08). Trace metal data clearly suggest that groundwater is free from any metal pollution. Dissolved silica (SiO$_{2}$) levels range from 34 to 131 mg/L and do not show any particular spatial trend. Isotope data infer that groundwater is recharged by rainwater after undergoing evaporation ($\delta^{18}$O: −6.0 per thousand), which matches with that of the combined isotope signature ($\delta^{18}$O: −5.5 per thousand) of SW and NE monsoon rainfall. $\delta^{18}$O–TDS correlations and hydrochemical facies evolution (HFE) diagram do not infer any seawater intrusion into these coastal aquifers.
$\bf{Highlights}$
$\bullet$ The composite water quality indices infer good to excellent category for drinking and agriculture.
$\bullet$ Mineral weathering, evaporite dissolution and base-exchange reactions are the main geochemical processes.
$\bullet$ Dissolved silica occurrence in groundwater is sporadic.
$\bullet$ Isotope indicators show the signature of both SW and NE monsoons recharge to groundwater.
$\bullet$ Observed brackishness in groundwater is due to water – rock interaction and not due to sea water intrusion.
Volume 129, 2020
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