fluxes varied between 3.15 and 37.3mg m-2 day-1 with the mean value of 14.6 mgm- 2day-1.The export carbon flux was on average 79mgm- 2day-1. The biogenic opal made up approximately 70% of the total.
3-2. Organic carbon removal rate in the Western Pacific
The estimation of organic carbon removal rate was carried out based upon our results. Due to significant loss of organic carbon during particle sinking, organic carbon fluxes were normalized to 100m water depth, using the organic carbon flux-depth relationship of Martin et al. (1987). For 'long-log slope' a value of -0.858 was used. As we mentioned before, 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 (Table 1). Sediment trap experiments gave the mean organic carbon export fluxes of 18mgC m-2day-1 from average flux at Sites 3 and 4 in Equatorial region, 27mgC m-2 day-1 from low flux period from .June to December at Site 6 in Subtropical gyre, 47mgC m-2day-1 from average flux at Sites5 and 7 in Kuroshio extenSion and 79mgC m-2day-1 from average flux at Site 8 in Subarctic region. Total area of this region from 0 to 48°N between 150 and 180°E is 15.723 × 106 km3. Therefore, organic carbon removal rate at 100m water depth is calculated to be 0.23 GtC yr-1.
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