Persistent organic pollutants in the equatorial atmosphere over the open Indian Ocean.
Twelve air samples collected over the Indian Ocean by a high volume air sampler between August 2004 and August 2005 were analyzed for selected polychlorinated biphenyl (PCB) congeners and organochlorine pesticides. The region of the Indian Ocean and adjacent countries is likely to be acting as a source of selected POPs to the global environment. Data were compared with those reported for the last 30 years to examine historical trends of selected persistent organic pollutants (POPs) over the Indian Ocean. Compound concentrations were influenced by the proximity to land and air mass origins. Higher concentrations of atmospheric sigmaPCBs (50-114 pg m(-3)) were found on the remote islands of Chagos Archipelago and Gan, Maldives, and in the proximity of Jakarta, Indonesia, and Singapore. Military activities and unregulated waste combustion were identified as possible sources for atmospheric PCB contaminations at the more remote areas. The highest concentrations of organochlorine pesticides were found adjacent to the coastline of Sumatra and Singapore, where sigmaDDTs (dichlorodiphenyltrichloroethane) and sigmaHCHs (hexacyclohexanes) were as high as 30 and 100 pg m(-3), respectively. A comparison study for the last 30 years over six regions of the Indian Ocean showed that the concentrations of organochlorine pesticides have declined significantly, by a magnitude of two, since the mid 1970s, but were highest at the beginning of the 1990s. The time trend of PCB contamination in the atmosphere over the Indian Ocean is less apparent. The decline of atmospheric POPs over the Indian Ocean may be due to international regulation of the use of these compounds.
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Republic of Singapore 117576. oliverwurl@nus.edu.sg
Oliver
O
Wurl
John Robert
JR
Potter
Jeffrey Philip
JP
Obbard
Caroline
C
Durville
D000393:Air Pollutants / Q000032:analysis*; D001272:Atmosphere; D008401:Gas Chromatography-Mass Spectrometry; D009930:Organic Chemicals / Q000032:analysis*; D011786:Quality Control
D000393:Air Pollutants; D009930:Organic Chemicals