Lateral transport of settling particles in the Ross Sea and implications for the fate of biogenic material

The Ross Sea, Antarctica, with its high rates of primary productivity and biogenic accumulation, provides an important location to test the validity of a one-dimensional particle-settling model. As part of an interdisciplinary field project performed from 1990 to 1992 to examine cycling and accumulation of biogenic matter in the Ross Sea, water-column particulate and current data were collected at three sites. At each of the sites, a current meter and sediment trap were placed 240 m below the water surface, and a similar set of instruments was located 40 m above the seabed. The moorings were deployed for 1- to 2-years duration. The current-meter records showed that the speed of flow in the southwestern Ross Sea is relatively slow (< 20 cm s(-1)) and current direction is highly variable. Currents in the south-central Ross Sea have moderate speeds (< 40 cm s(-1)) and less directional variability. The northwestern Ross Sea has the strongest flows (> 50 cm s(-1)) and least variability in direction. To examine the validity of a one-dimensional approximation for fluxes of biogenic material, two models were developed to determine the net displacement of particles settling through the water column. Current-meter data and particle-settling characteristics were incorporated in both models. One model produced a time-varying, linearly interpolated current field between the moorings in which particle advection was evaluated, The second model used time-averaged progressive-vector plots to estimate lateral particle advection, Results show that particles are displaced the least at the southwestern site (<20 km), moderate distances at the south-central site (<50 km), and the greatest at the northwestern site (>50 km), The pattern in displacement trends correlates well with observed sediment types and accumulation rates at each site, A one-dimensional model for the settling of biogenic material is most applicable at the southwestern site and least applicable at the northwestern site.