Seasonal variation of atmospheric organochlorine pesticides and polybrominated diphenyl ethers in Parangipettai, Tamil Nadu, India: Implication for atmospheric transport

Abstract

Past studies have reported several persistent organic pollutants (POPs) in different environmental matrices from a tropical coastal site, Parangipettai (PI), located along the bank of the Vellar River in Tamil Nadu, south India. Hence to fill the data gap after the strict ban on several POPs, high volume air sampling was conducted in PI to study the variability of atmospheric organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) during summer, pre-monsoon and monsoon seasons. Emission source regions were tracked by using five days back trajectory analysis. Range of air concentrations in pg/m3 were: dichlorodiphenyltrichloroethane (DDT), 13 - 1976; hexachlorocyclohexane (HCH), 260–1135, hexachlorocyclobenzene (HCB), 52–135, chlordanes, 36–135 and endosulfans, 66–1013. Six PBDE congeners ranged between 25 and 155 pg/m3 with the highest concentration in summer followed by pre-monsoon and monsoon. Atmospheric DDT and HCH in PI have drastically reduced from the past report thereby showing the strict ban on agricultural use of these compounds. During monsoon, fresh source of o,p′‐DDT, trans‐chlordane and α‐endosulfan was evident. Higher level of endosulphan sulfate in PI seems to be likely affected by the air mass, originating from a neighbouring state Kerela, where endosulfan has been extensively used for cashew plantations. Similarly in summer, the day recorded with the highest level of PBDEs, the sample was concurrently impacted by air parcel comprised of two major clusters, 1 (25%) and 2 (49%) that traversed through the metropolitan cities like Bangalore and Chennai. Dominance of BDE-99 over BDE-47 in PI is in line with the PBDE profile reported from Chennai city during similar time frame. Average concentration of tetra and penta BDE congeners in summer samples were nearly 2–3 folds higher than pre-monsoon or monsoon. Given the fact that strong localised sources for heavier BDE congeners are lacking in PI, regional atmospheric transport from the strong emission source regions in Chennai might have impacted PBDE concentration in PI.