Study on material circulation in the northwest Pacific Ocean based on sediment trap.

海沟是全球环境中最后一个未被开发的区域。自1986年8月以来，我们一直在日本海沟最深的部分继续进行泥沙捕集实验。一个圈闭设在水底以上400m处，另一个设在中层4~5000m处，自1990年以来又增加了约1000m和3500m水深的两个圈闭。主要研究结果如下：1)海沟区总质量和有机质的垂直通量高于其他海区；2)总颗粒物通量具有明显的时间变化，但这不仅仅与表层生产力有关；3)总体上，深层圈闭比浅层圈闭收集更多的物质，表明再悬浮物质从沟槽斜坡中迁移；4)放射性同位素、有机质组成以及球藻和有孔虫等微化石测试表明，再悬浮物质的通量很高。5)浮游生物测试，如硅藻、放射虫、球藻、有孔虫、有孔虫等。和孢粉形藻的通量和种类组成具有明显的季节变化。它们受表层产量、碳酸钙溶解速率和圈闭上方水体变化的影响。6)有孔虫个体的氧和碳同位素测量表明，测试的同位素组成基本上受标本生长所在海水的温度和碳同位素控制。

The oceanic trenches are the last unexplored region of the global environment. We have been continuing a time series of sediment trap experiments in the deepest part of the Japan Trench since August 1986. One trap was set 400 m above the bottom and other was set at the mid-depth of 4-5000 m. Two more traps were added at about 1000 m and 3500 m water depths since 1990. The following main results were obtained.1) Vertical flux of total mass and organic materials in the trench areas were relatively higher than those measured in other oceanic areas.2) A significant temporal variation of total particle flux was observed, but it is not simply related with the surface productivity.3) In general, the deeper trap collected more materilas than the shallow one, indicating transportation of resuspended matter from the trench slope.4) High fluxes of resuspended matter are suggested by the analysis of radio-isotopes, organic material composition, as well as microfossil tests such as coccolith and foraminifera.5) Planktonic tests such as diatom, radiolaria, coccolith, foraminifera, and palynomorph show distinct seasonal variations in their fluxes and species compositions. They are affected by the production rate in the surface layer, dissolution rate of the calcium carbonate, and changes of the water mass above the traps.6) Oxygen and carbon sotopic measurements of individual spciemens of foraminifera indicate that the isotopic compositions of the test are essentially controlled by the temperature and carbon isotope of the sea water in which the specimen grew.