Groundwater arsenic contamination – a multi- directional emerging threat to water scarce areas of Pakistan

Groundwater arsenic contamination has exponentially endangered the human life and complicated the efforts for obtaining and maintaining drinking water quality standards in Pakistan, particularly in the central and southern parts of the country. In the province of Sindh, groundwater arsenic concentration has reached up to 1100 μg/L against WHO limits of 10 μg/L. In the province of Punjab, over 20% and in the province of Sindh, around 36% of the population is exposed to arsenic contamination above WHO limits. Therefore, keeping in view the catastrophic situation, study on arsenic prevalence in the small village Bhutewan (which fulfils all the prerequisites for arsenic prevalence) district Rahim Yar Khan, Pakistan was carried out. During the year 2004, 13 water sources were tested having depth ranging from 14-50 m and the arsenic contamination between 150 μg/L to 400 μg/L was found in all the 13 water samples with minimum concentration of 50 μg/L at 45 m depth and maximum arsenic concentration of 400 μg/L at 13 ft (3 m). Positive correlation between Fe concentration and arsenic concentration in samples indicated the reductive dissolution of arsenic bearing iron (hydro)oxides. In 2005, with the collaboration of UNICEF, 19307 water sources were tested in district Rahim Yar Khan and it was observed that out of 19307 samples, 9644 samples were within the safer limits <10 μg/L (49.95%) and the rest of 9663 samples (50.05%) were found with varying arsenic concentration from 20 μg/L to 500 μg/L. This paper is a part of the effort to evolve and develop a community based, sustainable arsenic mitigation system by establishing spatial and temporal prevalence of arsenic in the study area.