Perchlorate, chlorate and bromate in water samples from the South-West coast of India

Abstract

Occurrence of perchlorate (ClO4−), chlorate (ClO3−) and bromate (BrO3−) in public drinking, open well and surface water sources at 20 locations in the South-West coastal state of Kerala (India) is reported. The analysis was performed by high performance liquid chromatography interfaced with tandem mass spectrometry (HPLC–MS/MS). Irrespective of water source (public tap water, open well water and surface water) all the analyzed samples contained high levels of ClO4−, indicating its contamination throughout the region. The highest ClO4− level found was 91.4 μg/L, which is 3.7 times higher than US EPA recommendations. ClO3− and BrO3− were also detected in the samples, with highest concentrations of 177 and 5.34 μg/L respectively in tap water samples. Regression analysis showed moderate positive correlation between ClO4− and bromide (Br−) in tap water (r2=0.659) and open well water (r2=0.485) samples, respectively. Similar correlation was also observed between ClO4− and Cl− (r2=0.591) concentrations in well water samples, indicating sea water could be one of the probable sources in addition to ClO4− manufacturing in the area. This is the first report of high levels of ClO4− and ClO3− and detectable BrO3− in water samples from anywhere in India.