Organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in SingaporeÕs coastal marine sediments Oliver Wurl a,b, * , Jeffrey Philip Obbard a,b a Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore b Tropical Marine Science Institute, National University of Singapore, 14 Kent Ridge Road, Singapore 119223, Singapore Received 25 February 2004; received in revised form 11 August 2004; accepted 24 September 2004 Abstract Persistent organic pollutants (POPs) are ubiquitous pollutants in the marine environment, particular in coastal areas affected by industry and shipping traffic. POPs are known for their recalcitrance and toxicity in the environment, and there is increasing concern over their global distribution and impact upon wildlife. Marine surface sediment samples taken within 6 km of the coastline of Singapore were analyzed to determine prevailing concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyl (PCBs) and polybrominated diphenyl ethers (PBDEs). Total PCB concen- trations varied widely from 1.4 to 329.6 ng/g (average 73.9 ng/g), where high concentrations were detected at sample locations closest to industrial areas with intensive shipping traffic. Total DDT concentrations ranged from 2.2 to 11.9 ng/g (average 6.7 ng/g) and were lower than the concentration range of 3.3–46.2 ng/g measured for total HCH (average 18.1 ng/g). Ratios of DDT/(DDE + DDD) in sediments do not indicate recent inputs of DDT into SingaporeÕs marine environment, but high concentrations of a-HCH and c-HCH show evidence for the usage of HCHs in Southeast Asia. Peak concentrations of cis- and trans-Chlordane were 10 ng/g. Among the PBDE congeners BDE 47, 99, and 100 only BDE 47 could be detected at a range of 3.4–13.8 ng/g (average 6.2 ng/g). The levels of OCPs, PCBs and PBDEs were compared to available data for other countries in Asia, and indicated relatively moderate levels of contamination. Peak concentrations of PCBs, HCH isomers, Chlordane, Heptachlor, Heptachlor epoxide and Dieldrin have the poten- tial to induce ecotoxicological impacts based on levels specified in the sediment quality standards of the USEPA and Canadian Council of Ministers of the Environment. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Organochlorine compounds; Polybrominated diphenyl ethers; Marine sediments; Singapore 1. Introduction Persistent organic pollutants (POPs) including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are of significant concern due their high toxicity and long environmental half-lives. Many POPs are 0045-6535/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2004.09.054 * Corresponding author. Address: Tropical Marine Science Institute, National University of Singapore, 14 Kent Ridge Road, Singapore 119223, Singapore. Tel.: +65 6774 9920; fax: +65 6774 9654. E-mail address: g0203875@nus.edu.sg (O. Wurl). Chemosphere 58 (2005) 925–933 www.elsevier.com/locate/chemosphere