Toxic fluoride and arsenic contaminated groundwater in the Lahore and Kasur districts, Punjab, Pakistan and possible contaminant sources

The present study is the first attempt to put forward possible sources of As, F− and SO42− contaminated groundwater in the Kalalanwala area, Punjab, Pakistan. Five rainwater and 24 groundwater samples from three different depths were analyzed. Shallow groundwater from 24 to 27 m depth contained high F− (2.47–21.1 mg/L), while the groundwater samples from the deeper depth were free from fluoride contamination. All groundwater samples contained high As (32–1900 μg/L), in excess of WHO drinking water standards. The SO42− ranges from 110 to 1550 mg/L. δ34S data indicate three sources for SO42− air pollutants (5.5–5.7‰), fertilizers (4.8‰), and household waste (7.0‰). Our important finding is the presence of SO42−, As and F− in rainwater, indicating the contribution of these elements from air pollution. We propose that pollutants originate, in part, from coal combusted at brick factories and were mobilized promotionally by the alkaline nature of the local groundwater.