ORIGINAL PAPER Speciation and geospatial analysis of disinfection byproducts in urban drinking water A. Siddique • S. Saied • E. Zahir • Z. A. Nayyer • N. A. Zaigham Received: 27 December 2011 / Revised: 5 March 2013 / Accepted: 16 March 2013 / Published online: 4 May 2013 Ó Islamic Azad University (IAU) 2013 Abstract Trihalomethanes (THMs) are the most abun- dant disinfection byproducts (DBPs) of the chlorination disinfection. THMs speciation and their geospatial distri- bution were examined in 58 locations throughout the water distribution network of Karachi city. THMs (CHCl 3 , CHCl 2 Br, CHClBr 2 and CHBr 3 ) and physico-chemical parameters (pH, TDS, DO, Residual chlorine, temperature and TOC) were determined. CHCl 3 was the major THM found in all water samples of 58 locations, which accounted for 91.69 % of the total THMS followed by CHCl 2 Br (5.69 %), CHClBr 2 (1.78 %) and CHBr 3 (0.85 %). Total THMs level exceed the maximum con- tamination level of WHO and USEPA at some locations. Varying nature of correlation from high to low was found within THMs and among the physico-chemical parameters. GIS linked geospatial analysis revealed the association of THMs level with demographical and geological based variations from east to west of Karachi city. Continuous monitoring program and legislation for the contaminant levels were suggested to avoid adverse public health impact of THMs in drinking water supplies. Keywords Chlorination Á Chloroform Á Geographical information systems (GIS) Á Natural organic matters (NOMs) Á Trihalomethanes (THMs) Introduction Chlorine is the most commonly used disinfection agent in drinking water systems throughout the world due to its economical and disinfection efficiency among the other disinfectants. A growing concern has emerged among the public health communities in the recent past about the health threat due to disinfection residues and their byproducts. Use of disinfection byproducts (DBPs) reduces the risk of pathogenic contamination in the drinking water treatment process but may pose a serious threat due to the adverse health effects of the byproducts formed during the process. During chlorination a complex mixture of chlorine byproducts is formed and more than 600 different types of DBPs have been identified (Becher 1999; Richardson et al. 2007). Among chlorination DBPs major group of chemi- cals include trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), haloketones (HAKs), chloral hydrate (CH) and chloropicrin (CP) (Golfinopoulos et al. 2003; Golfinopoulos and Nikolaoub 2004; Kampioti and Stephanou 1999; Nikolaou et al. 1999). Free chlorine reacts with the natural organic matters (NOMs) mainly humic acid (HA) and fulvic acid (FA) in the drinking water streams to generate DBPs. THMs has been one of the most concerned DBPs among the scientific community and the regulating agencies because they have been recognized as potentially A. Siddique (&) Á Z. A. Nayyer Á N. A. Zaigham Unit for Ain Zubaida and Groundwater Research, King Abdulaziz University, Jeddah, Saudi Arabia e-mail: chm97@hotmail.com A. Siddique Á S. Saied Á E. Zahir Department of Chemistry, University of Karachi, Karachi 75270, Pakistan A. Siddique ars Power Design Ltd, 4891 Dundas Street W, Toronto, ON M9A1B2, Canada Z. A. Nayyer Department of Applied Physics, University of Karachi, Karachi 75270, Pakistan 123 Int. J. Environ. Sci. Technol. (2014) 11:739–746 DOI 10.1007/s13762-013-0277-1