Spatial distribution and ecological risk assessment of short and medium chain chlorinated paraffins in water and sediments of river Ravi, Pakistan

Abstract

Short (SCCPs) and medium (MCCPs) chain chlorinated paraffins being the emerging organic pollutants have raised serious concerns due to their widespread use and related human health risks. However, their occurrence in aquatic bodies like rivers and associated damage to ecological integrity is yet unknown in some regions of the world. The current study is the first ever assessment of SCCPs and MCCPs in sediment and water of river Ravi, Pakistan. Spatial occurrence and associated ecological risks were investigated from sediments (n = 16) and composite water samples (n = 8) collected at eight locations along the stretch of river Ravi. The concentrations of SCCPs and MCCPs varied from below limit of detection (<LOD) to 19 ng/L and 25–55 ng/L in water, and <LOD-170 ng/g dw and <LOD-100 ng/g dw in sediments respectively. The median of MCCP/SCCPs ratio of water was high at 3.1 than 0.81 in sediments suggesting differential accumulation pattern of CPs in both matrices. Among carbon and chlorine homologues, C10,12,13 Cl7-8 and C14,16,17 Cl7-8 were dominant of SCCPs and MCCPs in water and sediments, respectively. The partitioning coefficient for organic carbon (log Koc) varied parabolically with chlorine number (P < 0.01) of SCCPs and MCCPs suggesting increased adsorption of medium chlorinated congeners in sediments. Ecological risk assessment illustrated limited effects on aquatic organism as a result of CPs exposure, however, their elevated concentrations predict ecological damage in future. Thus, in-depth investigation of CPs encompassing spatio-temporal distribution in water and sediments of rivers as well as their toxicity in aquatic organism including fish and human health is needful in future studies.