Particle fluxes and delta N-15 variation of sinking particles in the central Bransfield Strait (Antarctica)

Abstract

Sediment-trap deployment in the central Bransfield Strait during 1999/2000 shows distinct seasonal variation of particle fluxes, in which more than 99% of total annual flux occurred during a limited time. A more positive relationship between biogenic silica and total organic carbon fluxes in the intermediatewater sediment trap demonstrates that the surface-water production (mainly diatoms) played an important role in the supply of biogenic particles during the short period. The low delta N-15 values of particulate organic particles are attributed to high nitrate concentration in the Antarctic surface waters. The gradual increasing delta N-15 values in the bottom-water trap from the productive to unproductive season are likely associated with a switch in source from diatom aggregates to some remains of zooplankton, supplement to the horizontal contribution of lithogenic particles presumably from nearby shallow environment. Thus, the delta N-15 enrichment of sinking particles in the bottom-water trap during December to early February seems to be due to the laterally transported materials, assuming that the delta N-15 values decrease with depth in the Antarctic Polar Frontal region.