Persistent organohalogen contaminant burdens in Antarctic krill from the eastern Antarctic sector - BROKE-West Cruise

Researchers studied persistent organohalogen contaminants (POCs) in the eastern Antarctic sector. Samples were collected during January and February 2006 and originated from 12 sampling stations. They were analysed for greater than 100 organohalogen compounds including chlorinated pesticides, polychlorinated biphenyls (PCBs), polybrominated organic compounds and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs). The suspected naturally occurring organohalogen, 2,4,6-tribromoanisole (TBA) as well as delta-HCH; o,p'- DDE; o,p'-DDD; p,p'-DDD; p,p'-DDT; penta-chlorobenzene (PeCB); HCB; heptachlor-exoepoxide; heptachlor; trans-nonachlor, mirex and toxaphene congeners Tox-26 (B8-1413), Tox-40+41 (B8-1414+ B8-1945) and Tox-50 (B8-2229) were quantified in all samples analysed whilst PCB-101, gamma-HCH, p,p'-DDE cis-nonachlor, Tox-42a (B8-806) and Tox-44 (B8-2229) were quantified in greater than or equal to 75% of samples analysed. Organochlorine pesticides dominated measured krill contaminant burdens with hexachlorobenzene (HCB) as the single most abundant compound quantified: 4.37 ng/glw (lipid weight) or 0.2 ng/gww (wet weight). HCB concentrations were comparable to those detected at this trophic level in both the Arctic and temperate northwest Atlantic, lending support to the hypothesis that HCB will approach global equilibrium at a faster rate than other POCs. Para, para'-dichlorodiphenylethene (p,p'- DDE) was detected at notable concentrations: 2.6 ng/glw 0.13 ng/gww. In contrast to the Arctic, PCBs did not feature prominently in contaminant burdens of Antarctic krill: 1.2 ng g- 1 lw and 0.05 ng/gww., dominant PCB congeners were PCB-18, PCB-28, PCB-31 and PCB- 153. The major commercial polybrominated diphenyl ether (PBDE) congeners -99 and -47 were quantified at low background levels (0.67 ng/glw , 0.03 ng/gww and 0.35 ng/glw, 0.007 ng/gww respectively) with clear concentration spikes observed at around 70 degrees E , in the vicinity of modern, active research stations. The suspected naturally occurring brominated organic compound, 2,4,6-tribromoanisole (TBA), was a ubiquitous contaminant in all samples 49 whereas the only PCDD/Fs quantifiable were trace levels of octachlorodibenzo-p-dioxin (OCDD) and 1,2,3,4,7,8/1,2,3,4,7,9-hexachlorodibenzofuran (HxCDF).

This work has been incorporated in AAS project 3115 (ASAC_3115), Persistent Organic Pollutants and Emerging Contaminants of Concern; System Input From Local and Distant Contamination Sources.