Abstract

                                A study was undertaken with a view to assess the groundwater quality in the coastal areas of Thoothukudi district. 200 groundwater samples were collected from borewells, openwells and tubewells located five to ten kilometres from coastal line at regular intervals. The groundwater samples were analysed for pH, EC, TDS, TSS, anions (HCO₃^-, CO₃^2-, Cl^-, SO₄^2-) and cations (Ca²⁺, Mg²⁺, Na⁺, K⁺) by adopting standard procedures. Experimental results showed that the pH was slightly acidic to alkaline in nature varying from 6.38 to 8.65 and the electrical conductivity values of the samples ranged from 0.17 to 18.08 dS m^-1 i.e., good to alkali condition. From the study, it is concluded that the dominating ions in the groundwater samples of Thoothukudi district were Na⁺ and Cl^-. According to AICRP (1991) classification, 22.5 per cent of samples were good, 14 per cent were marginally saline, 15.5 per cent were saline, 4.5 per cent were high SAR saline, 23.5 per cent were marginally alkali and 20 per cent were alkali. This indicates that the groundwater in the study area were of Na-Cl type, indicating that they were largely intruded with seawater and are of poor quality.

Key words : Groundwater quality, Spatial distribution, Coastal areas, Thoothukudi district.