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 i nterdisciplinary field project performed from 1990 to 1992 to examine cycling and accumulation of biogenic matter in the Ross Sea, water-col umn particulate and current data were collected at three sites. At eac h of the sites, a current meter and sediment trap were placed 240 m be low 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 dura tion. The current-meter records showed that the speed of flow in the s outhwestern Ross Sea is relatively slow (< 20 cm s(-1)) and current di rection is highly variable. Currents in the south-central Ross Sea hav e moderate speeds (< 40 cm s(-1)) and less directional variability. Th e northwestern Ross Sea has the strongest flows (> 50 cm s(-1)) and le ast variability in direction. To examine the validity of a one-dimensi onal approximation for fluxes of biogenic material, two models were de veloped to determine the net displacement of particles settling throug h the water column. Current-meter data and particle-settling character istics were incorporated in both models. One model produced a time-var ying, linearly interpolated current field between the moorings in whic h particle advection was evaluated, The second model used time-average d progressive-vector plots to estimate lateral particle advection, Res ults show that particles are displaced the least at the southwestern s ite (<20 km), moderate distances at the south-central site (<50 km), a nd the greatest at the northwestern site (>50 km), The pattern in disp lacement trends correlates well with observed sediment types and accum ulation rates at each site, A one-dimensional model for the settling o f biogenic material is most applicable at the southwestern site and le ast applicable at the northwestern site.