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 sedim ent trap at three depths (1 and 2 km below the surface, and 0.7 km above th e sea-floor) was deployed in the western Pacific sector of the Southern Oce an, along 170 degreesW. The five stations were selected to sample settling particles in the main hydrological zones of the Southern Ocean. The samplin g period spanned 425 days (November 28, 1996-January 23, 1998) and was divi ded into 13 or 21 synchronized time intervals. A total of 174 sequential sa mples were recovered and analyzed to estimate fluxes of total mass (TMF), o rganic carbon, carbonate, biogenic silica, and lithogenic particles. The fl uxes of biogenic material were higher than anticipated, challenging the not ion that the Southern Ocean is a low-productivity region. Organic carbon fl uxes at 1 km depth within the Polar Frontal Zone and the Antarctic Zone wer e relatively uniform (1.7-2.3 g m(-2) yr(-1)), and about twice the estimate d ocean-wide average (ca. 1 g m(-2) yr(-1)). Carbonate fluxes were also hig h 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 t he north of the Polar Front, and calcium carbonate became the dominant phas e in the Subantarctic Zone. In contrast, carbonate particles were nearly ab sent near 64 degreesS. Latitudinal variations in biogenic silica fluxes wer e substantial. The large opal flux (57 g m(-2) yr(-1)) measured in the Anta rctic Zone suggests that opal productivity in this region has been previous ly underestimated and helps to explain the high sedimentary opal accumulati on often found south of the Polar Front. Unlike biogenic material, fluxes o f 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 Elsevie r Science Ltd. All rights reserved.