Particulate barium flux and its relationship with export production on the continental shelf of Prydz Bay, east Antarctica

Abstract

Particulate barium fluxes on the continental shelf of Prydz Bay in east Antarctica were measured by using time series sediment trap deployed at two stations with trap depth about 500m during 7/12/2009–15/2/2010 and 16/12/2010–16/12/2011. The annual fluxes were 12.3mgm−2yr−1 and 18.4mgm−2yr−1 for barium, and 8.9mgm−2yr−1 and 14.9mgm−2yr−1 for biogenic barium at two stations, respectively. More than 72% of the barium is from biogenic source. The temporal–spatial variations of biogenic barium fluxes and the ratio of biogenic barium to organic carbon are related to the variation of organic matter export in the upper water column. Biogenic barium flux and organic matter export are generally positive correlated. However, biogenic barium precipitation is less efficient under conditions of high organic matter exports during times of greater primary productivity, which leads to relatively less cycling of organic carbon and in turn produces less barite formation based on the hypothesis that barite forms through organic matter decomposing in microenvironment. More than 72% of the rained biogenic barium at the trap depth was preserved in the sediment. High preservation efficiency of biogenic barium and good relationship between biogenic barium and organic carbon suggested that biogenic barium could be a reliable proxy for the marine export production. The calculated export productions are 6.9gCm−2yr−1 and 14.9gCm−2yr−1 at two stations respectively using the modified prediction equation, which is more suitable for predicating export production for margin and shelf systems.