Assessing the influence of hydrogeochemical characteristics and microbial communities on monsoon dynamics in groundwater quality in north Chennai city, India

The current study evaluated the physicochemical, statistical, hydrogeochemical and biological characteristics of fifty groundwater samples that were taken from bore wells and tube wells in North Chennai, Tamil Nadu, India, in the monsoon seasons of November 2021 and November 2022. For the purposes of analysis and result interpretation, APHA standard procedures were used. The mean values of Total dissolved solids (TDS), Electrical conductivity (EC), Total hardness (TH), sodium and chloride (Cl⁻) surpassed the desired threshold specified by the World Health Organization (WHO). The Pearson coefficient of interaction showed that calcium hardness and TDS (0.940), as well as sodium and TDS (0.968), have high positive correlations. The strong correlation existed between Mg-Cl, Ca-Cl, Na-Cl, Na-SO₄, Na-Mg, Na-Ca and Mg-Ca ions with reference to both monsoon periods. While Gibb's plots indicated that evaporation and rock dominance were the main types, the sodium-chloride (Na-Cl) type was primarily shown in the Piper and Chadha models. Principal Component Analysis (PCA) identified Eigenvalues with 79.09% and 80.81% of the total variance during the monsoon periods of 2021 and 2022 respectively, which indicated seawater seepage into the coastal groundwater, soil-water interaction and anthropogenic activities. Pollution reasons were also evaluated for optimal management planning to safeguard the aquifer system. Based on the study of groundwater quality carried out in the research area, the concentration of Standard Plate Count (SPC), Total Coliforms (TC) bacterial influence have exceeded the permitted criteria in the majority of the sample locations (WHO).