234Th-based measurements of particle flux in surface water of the Bransfield Strait, western Antarctica

Abstract

Measurements of particulate and dissolved 234Th were carried out in March 2002 in the Bransfield Strait located between the Antarctic Peninsula and the South Shetland Islands. The 234Th/238U disequilibrium found in the upper water column has allowed evaluation of downward particle fluxes across a frontal zone, which divides water masses coming from the Bellingshausen Sea and the Weddell Sea. The highest particle flux has been found in this mixing zone, where it was 3–5 times greater than in the adjacent waters. Total mass fluxes in the upper 150-m water column were estimated as about 2.2 g m−2 day−1 in the eastern part of the Strait and 3.1 g m−2 day−1 in the western area.