Particle fluxes to the interior of the Southern Ocean in the Western Pacific sector along 170 degrees W

An array of five bottom-tethered moorings with 19 PARFLUX time-series sediment trap at three depths (1 and 2 km below the surface, and 0.7 km above the sea-floor) was deployed in the western Pacific sector of the Southern Ocean, along 170 degreesW. The five stations were selected to sample settling particles in the main hydrological zones of the Southern Ocean. The sampling period spanned 425 days (November 28, 1996-January 23, 1998) and was divided into 13 or 21 synchronized time intervals. A total of 174 sequential samples were recovered and analyzed to estimate fluxes of total mass (TMF), organic carbon, carbonate, biogenic silica, and lithogenic particles. The fluxes of biogenic material were higher than anticipated, challenging the notion that the Southern Ocean is a low-productivity region. Organic carbon fluxes at 1 km depth within the Polar Frontal Zone and the Antarctic Zone were relatively uniform (1.7-2.3 g m(-2) yr(-1)), and about twice the estimated ocean-wide average (ca. 1 g m(-2) yr(-1)). Carbonate fluxes were also high and uniform between the Subantarctic Front and ca. 64 degreesS (11-13 g m(-2) yr(-1)). A large fraction of the carbonate flux in the Antarctic Zone was due to the presence of pteropod shells. Coccoliths were found only to the north of the Polar Front, and calcium carbonate became the dominant phase in the Subantarctic Zone. In contrast, carbonate particles were nearly absent near 64 degreesS. Latitudinal variations in biogenic silica fluxes were substantial. The large opal flux (57 g m(-2) yr(-1)) measured in the Antarctic Zone suggests that opal productivity in this region has been previously underestimated and helps to explain the high sedimentary opal accumulation often found south of the Polar Front. Unlike biogenic material, fluxes of lithogenic particles were among the lowest measured in the open-ocean (0.12-0.05 g m(-2) yr(-1)), reflecting a very low dust input. (C) 2000 Elsevier Science Ltd. All rights reserved.