Understanding Levels and Sources of PAHs in Water of Bharalu Tributary of the Brahmaputra River

Polycyclic Aromatic Hydrocarbons (PAHs) were assessed in Bharalu River water of Guwahati city area during two seasons of 2012-2013. Water samples of seven representative locations were analysed for USEPA's priority 16 PAHs. PAHs were extracted from water samples by organic-aqueous partitioning and were cleaned up by a silica column. Qualitative and quantitative analysis of the PAHs were performed by HPLC. Concentrations of Σ $_{16}$ PAHs were found to be in the range 3.351-72.893 ng/ml. When compared with other studies elsewhere, levels of the present study were found to be on higher side. Profiles of PAHs were dominated by 3-, 4- and 5-ring compounds. Flan, Pyr, BaA, Chry, BkF, IP and Σ $_{16}$ PAHs showed good correlations with OC and TC. Sources of PAHs were empirically explored on the basis of diagnostic ratios, which indicated for pyrogenic sources mainly from diesel, gasoline, coal and wood combustion. Petrogenic signature ratios of PAHs were also found.