GEOCHEMICAL FACTORS AFFECTING THE POTENTIAL FOR DISINFECTION BYPRODUCT FORMATION IN GROUNDWATER FROM NORTHWESTERN INDIA

Climate conditions and human activities have reduced the usability of surface water in numerous places around world, including arid and semiarid parts of northwestern India. Urban areas that are particularly vulnerable to water stress have often turned to groundwater to help meet their water needs. Shallow groundwater is susceptible to anthropogenic inputs including bacteriological and chemical pollution, so water source disinfection, such as chlorination, is commonly employed to protect human health. However, disinfection carries its own set of risks in the form of disinfection byproducts (DBPs), carcinogenic chemicals that can be generated during the disinfection process.

In this study, we examine key geochemical and human factors that may result in the formation of DPBs in groundwater from Rajasthan. The combined effects of geogenic (e.g., recharge under arid conditions) and anthropogenic contamination have resulted in groundwater with elevated levels of bromide, iodide, and DOC, all known DPB precursors. Our data show that management practices such as transport of canal water with typically lower salinity and chlorination of imported surface water/ groundwater mixtures, affect the kind and amount of DBPs generated. We use a large dataset of drinking waters, including surface water, groundwater, and mixed waters from Rajasthan to explore the potential DBP formation for different populations and the tradeoff between risks from waterborne bacteriological contaminants versus formation of carcinogenic DBPs in drinking water supplies.