Hydro-Geo-Chemistry, Phytodiversity and Microbial Population in the Inland Water Bodies of the Subtropical City

Inland waters are a key component in nutrient recycling and primary productivity; however, it is experiencing stress due to urbanization and inadvertent inflow of sewage, altering their bio-geo-chemical composition. This study assessed the health of 19 inland water bodies in a subtropical city using an interdisciplinary bio-chemical approach. Physico-chemical variables, viz. TDS, EC, pH, alkalinity, total hardness, major cations (Ca2+, Na+, K+), and anions (HCO3-, Cl-, PO43-, SO42-) exceeded the BIS-prescribed limit for surface water. Macrophyte diversity serves as bioassay for assessing the cumulative impact of both known and unknown chemicals, while microbial diversity acts as an indicator of sewage discharge and pathogens. Abundance (%) of macrophytes was found in order of Pistias tratiotes (84.21%) >Lemna minor (78.94%) >Azolla pinnata (73.68%)>Eichhornia crassipes (73.68%) >Marsilea quadrifolia (52.63%) >Ipomoeaaquatica (47.37%) > Hydrilla verticilata (31.57%), and reflects the state of eutrophication and ageing. The presence of E. coli indicates faecal contamination across all the water bodies. Water Quality Index revealed that 79% of water bodies were ‘unsuitable’ for drinking, while 16% and 5% were ‘poor’ and ‘very poor’, respectively. Findings underline the threat of human activities to these freshwater ecosystems and warrant revival and conservation efforts.