(Table 1) Neutral and phenolic organohalogen compounds in blubber samples of ringed seals (Pusa hispida) from East Greenland@en

We report on the comparative bioaccumulation, biotransformation and/or biomagnification from East Greenland ringed seal (Pusa hispida) blubber to polar bear (Ursus maritimus) tissues (adipose, liver and brain) of various classes and congeners of persistent chlorinated and brominated contaminants and metabolic by-products: polychlorinated biphenyls (PCBs), chlordanes (CHLs), hydroxyl (OH-) and methylsulfonyl (MeSO2-) PCBs, polybrominated biphenyls (PBBs), OH-PBBs, polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) flame retardants and OH- and methoxyl (MeO-) PBDEs, 2,2-dichloro-bis(4-chlorophenyl)ethene (p,p'-DDE), 3-MeSO2-p,p'-DDE, pentachlorophenol (PCP) and 4-OH-heptachlorostyrene (4-OH-HpCS). We detected all of the investigated contaminants in ringed seal blubber with high frequency, the main diet of East Greenland bears, with the exception of OH-PCBs and 4-OH-HpCS, which indicated that these phenolic contaminants were likely of metabolic origin and formed in the bears from accumulated PCBs and octachlorostyrene (OCS), respectively, rather than being bioaccumulated from a seal blubber diet. For all of the detectable sum of classes or individual organohalogens, in general, the ringed seal to polar bear mean BMFs for SumPCBs, p,p'-DDE, SumCHLs, SumMeSO2-PCBs, 3-MeSO2-p,p'-DDE, PCP, SumPBDEs, total-(alpha)-HBCD, SumOH-PBDEs, SumMeO-PBDEs and SumOH-PBBs indicated that these organohalogens bioaccumulate, and in some cases there was tissue-specific biomagnification, e.g., BMFs for bear adipose and liver ranged from 2 to 570. The blood-brain barrier appeared to be effective in minimizing brain accumulation as BMFs were <= 1 in the brain, with the exception of SumOH-PBBs (mean BMF = 93±54). Unlike OH-PCB metabolites, OH-PBDEs in the bear tissues appeared to be mainly accumulated from the seal blubber rather than being metabolic formed from PBDEs in the bears. In vitro PBDE depletion assays using polar bear hepatic microsomes, wherein the rate of oxidative metabolism of PBDE congeners was very slow, supported the probability that accumulation from seals is the main source of OH-PBDEs in the bear tissues. Our findings demonstrated from ringed seal to polar bears that organohalogen biotransformation, bioaccumulation and/or biomagnification varied widely and depended on the contaminant in question. […]本研究报道了从东格陵兰环斑海豹（Pusa hispida）鲸脂到北极熊（Ursus maritimus）组织（脂肪组织、肝脏与大脑）中，各类持久性氯代、溴代污染物及代谢副产物的不同类别与同系物的比较性生物富集、生物转化及/或生物放大过程，涉及的污染物包括：多氯联苯（PCBs）、氯丹类（CHLs）、羟基（OH-）与甲磺酰基（MeSO2-）多氯联苯、多溴联苯（PBBs）、羟基多溴联苯（OH-PBBs）、多溴二苯醚（PBDE）与六溴环十二烷（HBCD）阻燃剂，以及羟基（OH-）与甲氧基（MeO-）多溴二苯醚、2,2-二(对氯苯基)二氯乙烯（p,p'-DDE）、3-甲磺酰基-p,p'-DDE、五氯苯酚（PCP）与4-羟基七氯苯乙烯（4-OH-HpCS）。我们在作为东格陵兰北极熊主要食物来源的环斑海豹鲸脂中，高频检出了所有目标污染物，仅羟基多氯联苯（OH-PCBs）与4-羟基七氯苯乙烯（4-OH-HpCS）除外。这表明此类酚类污染物大概率源自代谢过程：前者由北极熊体内蓄积的多氯联苯转化生成，后者则由八氯苯乙烯（OCS）转化而来，而非通过摄食海豹鲸脂直接生物富集获得。针对所有可检出的同类或单一有机卤化物总和而言，总体来看，从环斑海豹到北极熊的Σ多氯联苯（SumPCBs）、p,p'-DDE、Σ氯丹类（SumCHLs）、Σ甲磺酰基多氯联苯（SumMeSO2-PCBs）、3-甲磺酰基-p,p'-DDE、五氯苯酚（PCP）、Σ多溴二苯醚（SumPBDEs）、总α-六溴环十二烷（total-(α)-HBCD）、Σ羟基多溴二苯醚（SumOH-PBDEs）、Σ甲氧基多溴二苯醚（SumMeO-PBDEs）与Σ羟基多溴联苯（SumOH-PBBs）的平均生物放大因子（BMF）均表明，此类有机卤化物可发生生物富集，部分污染物还呈现组织特异性生物放大现象：例如北极熊脂肪组织与肝脏的BMF值介于2至570之间。血脑屏障似乎可有效限制脑组织的污染物蓄积，除Σ羟基多溴联苯外（平均BMF=93±54），北极熊脑组织的BMF值均≤1。与羟基多氯联苯代谢物不同，北极熊组织中的羟基多溴二苯醚主要通过摄食海豹鲸脂富集而来，而非由北极熊体内的多溴二苯醚代谢转化生成。利用北极熊肝微粒体开展的体外多溴二苯醚耗竭实验结果显示，多溴二苯醚同系物的氧化代谢速率极慢，这进一步佐证了"北极熊组织中的羟基多溴二苯醚主要源自海豹鲸脂富集"这一推论。本研究结果表明，从环斑海豹到北极熊的食物链中，有机卤化物的生物转化、生物富集与/或生物放大过程差异显著，且具体表现取决于目标污染物的种类。[…]