Export production plays an important role in the interaction of carbon transfer between the ocean and the atmosphere. Few data on sinking particles have been reported from the open sea of the Western Pacific. Here we present the results on sinking particles collected with six moorings of sediment traps which were deployed along 175｡?. The sites were located at 0｡?, 8｡?, 30｡?, 34｡? (178｡?) 37.5｡? and 46｡?, respectively. Surface water in the Western Pacific can be classified into four zones: 1) Equatorial region, 2) Subtropical gyre, 3) Kuroshio extension and 4) Subarctic region. Sediment trap experiments gave the mean organic carbon export fluxes of l8mgC m-2day-1 from Equatorial region, 27mgC m-2day-1 from Subtropical gyre, 47mgC m-2day-1 from Kuroshio extension and 79mgC m-2day-1 from Subarctic region. Estimation of net C removal flux in the Western Pacific (0-48｡?, 150-180｡?) gives 0.23 GtCyr-1 at 100m water depth.
1. INTRODUCTION
Vertical mass transport with sinking particles is one of the most important processes in biogeochemical cycles in the ocean. It is the major contributor to deep sea sediments in the open ocean. Also it is responsible for the chemical differences between the surface water and the deep water. Particle composition, seawater chemistry of the water column, water depth and settling velocity are major factors to modify the fluxes and compositions of sinking particles. Primary productivity of the global ocean is estimated to be 22-45GtC per year (Sundquist, 1985), which is three to seven times higher than he amounts of CO2 emitted by combustion of fossil fuels (Koblentz-Mishke et al., 1970; Eppley, 1989).
The results of numerous sediment trap experiments suggest that vertical fluxes are highly variable both in fluxes and compositions of the sinking particles (e.g., Honjo et al., 1982; Ittekkot et al., 1991). Organic carbon fluxes of sinking particles are generally affected by primary productivity. In the Western Pacific, primary productivity shows large gradient from Subtropical gyre to Equatorial region and
