外洋域の沈降粒子-堆積粒子からの古海洋の復元のために- Sinking Particles and Sedimentary Particles
Bottom sediments in the open sea mainly originate from sinking particles. Therefore it is very important to investigate chemical properties, seasonality and interannual variability of sinking particles in order to reconstruct paleoenvironments in more detail. Data sets on total, carbonate, organic matter, and biogenic opal fluxes which were measured for more than 5 months are compiled from various areas of the world ocean. Mean total fluxes vary from 0.1 to 16.7 mg Cm<SUP>-2</SUP> day<SUP>-1</SUP> They reflect primary productivity. The enhanced values are observed in arctic, subarctic and equatorial upwelling regions. In general they decrease from coastal region to open sea. Although mean carbonate and biogenic fluxes generally reflect primary productivity, biogenic opal fluxes fluctuated more than carbonate fluxes. Carbonate and biogenic opal are dissolved in the deep sea, therefore it needs much efforts to reconstruct original assemblages of biogenic skeletons.<BR>Particle fluxes are affected by river input and upwelling induced by Asian monsoon, upwelling in coastal and equatorial regions, sea ice formation, and volcanic eruption. Long term sediment trap experiments evaluate the surface to the deep sea and/or seafloor, which is one of the most important subjects for understanding paleoenvironments.