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.

研究人员针对南极东部区域的持久性有机卤化物污染物（persistent organohalogen contaminants, POCs）开展了研究。研究样本于2006年1月至2月期间采集，共涵盖12个采样站位。本次分析共覆盖100余种有机卤化物化合物，包括氯化农药、多氯联苯（polychlorinated biphenyls, PCBs）、多溴有机化合物以及多氯代二苯并二噁英/呋喃（polychlorinated dibenzo-p-dioxins/furans, PCDD/Fs）。

所有受分析样本中均定量检出了疑似天然存在的有机卤化物——2,4,6-三溴苯甲醚（2,4,6-tribromoanisole, TBA），以及δ-六氯环己烷、邻,对'-二氯二苯二氯乙烯、邻,对'-二氯二苯二氯乙烷、对,对'-二氯二苯二氯乙烷、对,对'-二氯二苯三氯乙烷、五氯苯（penta-chlorobenzene, PeCB）、六氯苯（hexachlorobenzene, HCB）、环氧七氯、七氯、反式九氯、灭蚁灵，以及毒杀芬同系物Tox-26（B8-1413）、Tox-40+41（B8-1414+B8-1945）与Tox-50（B8-2229）；而PCB-101、γ-六氯环己烷、对,对'-二氯二苯二氯乙烯、顺式九氯、Tox-42a（B8-806）与Tox-44（B8-2229）则在≥75%的受分析样本中实现定量检出。

在测得的南极磷虾污染物负荷中，有机氯农药占主导地位，其中六氯苯（HCB）为单一种类丰度最高的定量化合物：其浓度为4.37纳克/克脂重，或0.2纳克/克湿重。六氯苯的浓度水平与北极及温带西北大西洋同营养级海域的检出浓度相当，这为“六氯苯相较于其他持久性有机卤化物污染物可更快达到全球均衡状态”的假说提供了支撑。对,对'-二氯二苯二氯乙烯（p,p'-DDE）的检出浓度同样可观：达2.6纳克/克脂重与0.13纳克/克湿重。

与北极海域不同，多氯联苯在南极磷虾的污染物负荷中并不占主导地位，其浓度仅为1.2纳克/克脂重与0.05纳克/克湿重；占比最高的多氯联苯同系物为PCB-18、PCB-28、PCB-31与PCB-153。商用主流多溴二苯醚（polybrominated diphenyl ether, PBDE）同系物PBDE-99与PBDE-47的定量浓度处于较低背景水平（分别为0.67纳克/克脂重、0.03纳克/克湿重，与0.35纳克/克脂重、0.007纳克/克湿重）；而在东经约70度、临近现行活跃科研站的区域，观测到了显著的浓度峰值。前述疑似天然存在的溴代有机化合物2,4,6-三溴苯甲醚（TBA）在所有样本中均为普遍存在的污染物；而本次可定量检出的多氯代二苯并二噁英/呋喃仅为痕量水平的八氯代二苯并二噁英（octachlorodibenzo-p-dioxin, OCDD）与1,2,3,4,7,8/1,2,3,4,7,9-六氯代二苯并呋喃（hexachlorodibenzofuran, HxCDF）。

本项研究已纳入AAS项目3115（ASAC_3115）——《关注持久性有机污染物与新型污染物：本地与远端污染源的系统输入》。