Particle fluxes and δ15N variation of sinking particles in the central Bransfield Strait (Antarctica)

摘要

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 intermediate-water 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 δ15N values of particulate organic particles are attributed to high nitrate concentration in the Antarctic surface waters. The gradual increasing δ15N 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 δ15N 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 δ15N values decrease with depth in the Antarctic Polar Frontal region.