BTEX contamination of Bengaluru aquifers, Karnataka, India

Abstract

Leakage from underground storage tanks (USTs) in petrol filling stations is a recognised pathway for contamination of aquifers by benzene, toluene, ethylbenzene and xylene (BTEX) compounds. Bengaluru City, India, partially depends on groundwater for potable water and has a specific climatic condition of wet and dry seasons. Hence, the influence of temporal rainfall variations on possible BTEX contamination of groundwater from leaky USTs was examined by testing tube-well samples located at petrol filling stations and their vicinities in Bengaluru City during pre- and post-monsoon periods. Groundwater samples were collected from tube wells located at petrol filling stations or their vicinities during post-monsoon (September 2015–January 2016) and subsequent pre-monsoon (March–April 2016) periods. Variations in BTEX concentrations during post- and pre-monsoon periods highlighted the influence of season on BTEX concentrations in the aquifer, as higher BTEX concentrations were generally observed in groundwater samples during post-monsoon than pre-monsoon. The results of the study show that BTEX contamination of Bengaluru aquifers from leaky USTs in petrol filling stations is not extensive as only 5% of groundwater samples showed benzene presence in excess of the permissible limit, while toluene, ethylbenzene and xylene compounds were below permissible limit in all the 124 groundwater samples.