River pollution: Assessment of hydro-philic and phobic nature of persistent organic contaminants

Natural purification of persistent organics by sorption during riverbank filtration (RBF) depends on their hydrophilic or hydrophobic nature. It can be ascertained by octanol/water partition coefficient (KOW) and specific ultra violet absorbance (SUVA). This motivated the authors to analyze KOW and SUVA, firstly, of some mixed synthetic samples of organics and secondly, of polluted water samples from the River Hindon. Monthly water samples of the Hindon were collected from five locations (latitude 28°38′08.64″ to 29°36′42.55″N and longitude 77°23′38.27″ to 77°34′19.38″E) and were analyzed for cumulative water-quality parameters total organic carbon (TOC), UV-A, biochemical oxygen demand (BOD) and chemical oxygen demand (COD). The low ratio of BOD5-COD (∼0.13) is indicative of persistent nature of organics in the river water. Organics in the water samples were also analyzed by GC–MS and their log KOW values were obtained from the literature ranged from −0.84 to 2.15. Log KOW values of the water samples from four locations were between 0.11 and 0.37 but were around −0.43 at the fifth locations. Similarly, SUVA values of water from the same four locations were between 0.64 and 0.80 whereas the SUVA of the fifth water sample varied from 0.49 to 0.59. Both SUVA and KOW values reveal hydrophilic nature of the Hindon water samples.