Occurrence of Polycyclic Aromatic Hydrocarbons (Pahs) in Beached Plastic Pellets from Mumbai Coast, India

Abstract

PAHs are a class of ubiquitous pollutants that are found in polluted marine areas whichconsist of two or more fused benzene rings in various arrangements. There are over 100different PAH compounds. A number of PAH compounds are known carcinogens andbioaccumulate and biomagnify. These compounds originate naturally as well asanthropogenically through oil spills, incineration of waste and combustion of fossil fuels andwood. Plastic pellets (small granules 1-5 mm in diameter) are the raw material used for theproduction of many different plastic products. The environmental consequence of theseorganic polymers is the sorption organic pollutants on their surface from the sea surfacemicrolayer (SML) where the hydrophobic contaminants are known to be enriched. Theplastic pellets were collected along the recent high tide line from four beaches of Mumbaicoast bimonthly during May 2011 - March 2012. A total of 72 pools of plastic pellets wereextracted, fractionated and analysed by Gas Chromatograph coupled to a mass spectrometerto evaluate the extent and sources of 16 polycyclic aromatic hydrocarbons (PAHs) of thepriority list of the U.S. Environmental Protection Agency (EPA) The mean ΣPAHconcentration in pellets was 9202.30±114.89 ng g-1 with a wide range (35.4-46191.58 ng g-1). The concentration of fluorene was found to be the highest (1606.30±251.54 ng g-1)followed by anthracene, chrysene and phenanthrene. The ΣPAH concentration wassignificantly varied among months and there was no significant difference among sites atp=0.05. The 2-3 aromatic ring compounds accounted for 60% of the total PAHs in pellets ofMumbai coast while 4 rings and 5-6 rings compounds accounted for 26 and 14%,respectively. The ratio of low and high molecular weight PAHs indicated that thecontamination by petrogenic sources was predominant over the pyrogenic ones in plasticpellets suggesting oil pollution in coastal area of Mumbai.