Distribution, Transport and Accumulation Processes of Anthropogenic Pollutants in Oceanic and Deep-sea Ecosystems

为了评估人为污染物对深海生态系统的影响现状，在东南亚、赤道太平洋和日本中部相模湾的边缘海域进行了调查，分析了各种生态系统组成部分的污染物水平，包括中上层和底栖生物、海洋雪和底部沉积物，并特别参考了生物的生态特性，如它们的垂直分布和营养水平。对苏禄海中有机锡化合物、有机氯和多溴联苯醚的分析首次表明，这些化合物是在该地区的深海动物中积累的，但它们的含量低于西太平洋更北部的其他地区。在相模湾，从所有被分析的深海动物中都检测到有机锡化合物，包括中远洋微型动物、底栖无脊椎动物和底栖鱼类。微量元素和稳定同位素比值分析表明，δ^<15>N与Hg、Sn、Cs等元素呈正相关，与Cu、Mo、Ba等元素呈负相关，说明不同分类位置和生理生态特性的生物积累趋势不同。同时，对远洋组合垂直结构的研究表明，食草桡足类、以海洋雪为食的桡足类以及在污染物主动运输中进行显著垂直迁移的鱼类和十足类微浮游动物的重要性。对稳定同位素比率的分析表明，海面浮游植物吸附在海洋雪上的污染物通过另一种途径迅速下沉到海底，并与底栖生物群落结合。

To assess the present status of the impact of anthropogenic pollutants on deep-sea ecosystems, investigations were made in the marginal seas of Southeast Asia, the equatorial Pacific, and Sagami Bay, central Japan, and levels of pollutants were analyzed for various ecosystem components, including pelagic- and benthic organisms, marine snow, and bottom sediments with special reference to the ecological properties of the organisms, such as their vertical distributions and trophic levels. The analysis of organotin compunds, organochlorines and polybrominated diphenyl ethers in the Sulu Sea revealed, for the first time, that these compounds are accumulated in the deep-sea animals in the area, while their levels are lower than in the other, more northern areas of the western Pacific. In Sagami Bay, organotin compounds were detected from all deep-sea animals that were analyzed, including mesopelagic micronekton, benthic invertebrates and demersal fishes. The analysis of trace elements and stable-isotope ratios indicated positive correlations of of δ^<15>N with such elements as Hg, Sn, Cs, but negative correlations with others such as Cu, Mo, Ba, indicating different trends of accumulation between organisms of different taxonomic positions and with different physiological/ecological properties. Concurrent investigations on the vertical structure of pelagic assemblages suggested importance of herbivorous copepods, the copepods that feed on marine snow, and fish- and decapod micronekton that perform marked diel vertical migration in the active transport of the pollutants. An analysis of stable-isotope ratios suggested another pathway by which pollutants adsorbed on marine snow derived from surface phytoplankton quickly sink to the bottom to be incorporated into the benthic communities.