Dhakshinamoorthy R. and Selvarajan G.
Abstract
This study investigates the groundwater quality of Thanjavur District, Tamil Nadu, through the physicochemical and heavy metal analysis of ten samples collected post-monsoon 2024. The pH ranged from 6.72 to 7.16, indicating neutral to slightly acidic water. Electrical conductivity (EC) varied from 484 to 1027 ?S/cm, and total dissolved solids (TDS) ranged between 340 and 815 mg/l, with 50% of the samples exceeding the WHO limit (500 mg/l). Total hardness (TH) varied from 220 to 460 mg/l, with 60% of samples surpassing the BIS permissible limit (300 mg/l). Sodium ranged from 49 to 116 mg/l, while nitrate levels were low (0-6 mg/l). Fluoride and iron concentrations were within acceptable limits in most samples, except one where iron reached 0.3 mg/l. Chemical oxygen demand (COD) values ranged from 6.5 to 25 mg/l, exceeding WHO standards (10 mg/l) in 40% of samples, indicating possible organic pollution. Strong correlations were observed between EC and TDS (r = 0.91), sodium and COD (r = 0.78), and TH and calcium (r = 0.85). These results highlight potential geogenic and anthropogenic sources, calling for targeted water treatment and better groundwater management strategies.