DISSOLVED ALUMINUM IN THE WEDDELL-SCOTIA CONFLUENCE AND EFFECT OF AL ON THE DISSOLUTION KINETICS OF BIOGENIC SILICA

In the Scotia and Weddell Seas the concentration of dissolved Al was 1-1.5 nM in ice-free surface waters, up to 3 nM in ice-covered waters and about 2.6 nM in bottom waters. The solubility and the dissolution rate of diatomaceous silica, obtained from net samples and from incubations in the presence or absence of dissolved Al, were inversely related to solid-phase Al/Si ratios. At in situ temperatures, dissolution rates for Antarctic diatoms are higher than those for diatoms from temperate regions. Effects on distribution patterns of silicic acid in the Weddell Sea are discussed.