Occurrences of polycyclic aromatic hydrocarbon from Adayar and Cooum Riverine Sediment in Chennai city, India

In Chennai city, India, the industrial outfalls, port activities and anthropogenic activities dump a significant amount of waste in the riverine belts of two major rivers, viz. Cooum and Adayar. Hence, this paper aims to study the occurrences and sources of 16 priority polycyclic aromatic hydrocarbons (PAHs) enlisted in United States Environmental protection Agency. Gas chromatography-mass spectrometry analysis showed that total PAHs in surface riverine sediment ranged from 136 to 2063 ng/g (Average +/- SD, 654 +/- 801 ng/g dw) for Cooum and 105-1710 ng/g (Average +/- SD, 380 +/- 593 ng/g) for Adayar. Generally, high molecular weight PAHs were higher than low molecular weight PAHs. A prevalence of high molecular weight carcinogenic PAHs was suspected due to incomplete combustion. Principal component analysis and diagnostic ratios revealed that emission sources were from pyrogenic (vehicular emissions), as well as significant contribution was from petrogenic inputs. Principal component analysis also revealed that for both riverine sediments in PC1 65% of high molecular weight compounds were from informal e-waste recycling area and industrial corridor possibly associated with industrial effluents and recycling activities. The ecological risk assessment using probable effect level estimation suggested that PAHs are likely to cause no adverse effect or slightly adverse in all the sites of Cooum and Adayar excluding in residential sites (CR-03, AD-02) and e-waste site (CR-16) which were under heavy and moderate ecological impact. Further toxic equivalent factor also showed that residential site (AD-02) was affected by moderate level loading of benzo[a]pyrene.