Bioaccumulation of Dioxins Through Aquatic Food Chain

测定了新江湖和东京湾不同水生生物中的多氯二苯并对二恶英和二苯并呋喃(PCDD/DFS)和共面多氯联苯(co-PCBS)的污染水平。在由浮游生物、底栖生物、贝类和鱼类组成的水生食物链中，各共多氯联苯的同系物随着营养位置的增加而增加。与此相比，总PCDD/DFS浓度随着营养位置的增加而减少，而总PCDD/DF-TEQ(毒性当量)则随着营养位置的增加而增加。这些现象是由于不同的二恶英类同系物通过营养层(表示为生物体中的同系物浓度与每个同系物的稳定氮同位素比率之间的回归线的斜率)而具有不同的营养积累能力。The Nutic a…更多的累积能力被确定为如下顺序：单邻位多氯联苯和GT；非邻位多氯联苯和GT；2，3，7，8-取代的PCDD/DF同系物&GT；非2，3，7，8-取代的同系物。此外，在2，3，7，8-取代PCDD/DFS的情况下，随着辛醇-水分配系数(Kow)的增加，其效力降低，基于生物沉积积累因子(BSAF)的分析得到了类似的结果。浮游生物的2，3，7，8-PCDD/DF同系物的BSAF基本相同，但贝类和鱼类的BSAF随着Kow值的增加而降低，说明Kow值较高的2，3，7，8-同系物没有有效地转移到较高的营养层。在联合多氯联苯的情况下没有观察到这一现象。这些结果表明，氮同位素比值和污染的联合监测将为污染物在食物链中的生物积累提供更好的综合数据。较少

The contamination of levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and coplanar polychlorinated biphenyls (co-PCBs) were determined in various aquatic organisms from Lake Shinji and Tokyo Bay. In addition, stable nitrogen isotope ratios, which can be used as a parameter for quantifying trophic levels in the aquatic food chain, were determined.In the aquatic food chain, consist of plankton, benthic organisms, shellfish, and fish, each congener of co-PCB increased with the increasing trophic position. In contract to this, total PCDD/DFs concentration decreased with the increasing trophic position, while in total PCDD/DF-TEQ (toxic equivalents) increased with the trophic position. These phenomena were explained by the different trophic accumulation potency of various dioxin-like congeners through the trophic level (expressed as slope of regression line between congener concentration in organisms and stable nitrogen isotope ratio for each congener). The trophic a … More ccumulation potency were determined to be in the following order : mono-ortho-PCBs > non-ortho-PCBs > 2,3,7,8-substituted PCDD/DF congeners > non-2,3,7,8-substituted congeners. In addition, in the case of 2,3,7,8-substituted PCDD/DFs, the potency decreased with the increase of octanol-water partition coefficient (Kow).Analysis based on the biota-sediment accumulation factor (BSAF) gave the similar result explained above. The BSAFs for 2,3,7,8-PCDD/DF congeners were almost same for planktons, however, those for shellfish and fish decreased with the increase of Kow of those congeners, indicating that 2,3,7,8-congeners with higher Kow values are not efficiently transferred to higher trophic level. This phenomenon was not observed in the case of co-PCBs. BSAFs for co-PCBs were high and indicated to be efficiently transferred to higher trophic levels.These results showed that combined monitoring of nitrogen isotope ratio and contamination will give a better-synthesized data for bioaccumulation of pollutant through the food chain. Less