Aluminium and silicic acid in water and sediments of the Enderby and Crozet Basins

Sedimentary Diagenesis, Depositional Environments, and Benthic Fluxes

“…Experimental incubations of marine sediments and diatoms readily demonstrate rapid (0.1-2 year) nucleation and growth of aluminosilicates on frustules and other reactive siliceous substrates in seawater at low temperature (T < 30 C) (Loucaides et al, 2010;Michalopoulos and Aller, 1995;Michalopoulos et al, 2000). Consistent with observations of solids, studies of diatom frustule-rich Southern Ocean deposits have implicated control of pore water silicate concentrations by authigenic aluminosilicate formation during early diagenesis (Dixit et al, 2001;King et al, 2000;Rabouille et al, 1997;Van Beusekom et al, 1997;Van Cappellen and Qiu, 1997a,b). Perhaps most importantly in terms of global mass balance considerations, bottom waters and pore waters in a wide range of nearshore high sedimentation rate deltaic and estuarine environments also typically show regular stoichiometric relationships between dissolved Al and Si, indicative of extremely rapid, early diagenetic formation of authigenic aluminosilicates (Mackin, 1986;Mackin and Aller, 1984, 1989.…”

The mineral dissolution rate conundrum: Insights from reactive transport modeling of U isotopes and pore fluid chemistry in marine sediments

“…However, dissolved Al and Si in sediment pore waters commonly exhibit an inverse relationship (Caschetto and Wollast, 1979;Aller, 1984, 1986;Stoffyn-Egli, 1982;Van Beusekom et al, 1997). To define a range of expected values for Site 984 pore waters, measurements for Al and Si concentrations from other deep-sea pore waters were compiled and plotted (Fig.…”

“…16). The Mackin and Aller (1986) data are from pore waters in silicate-rich sediments in the Amazon Basin and the Van Beusekom et al (1997) measurements are from sediments with high contents of biogenic silica ($18 wt. %) in the South Sea.…”

Microbial mediation of benthic biogenic silica dissolution

“…According to Van Cappellen et al (2002), each of these factors may theoretically result in dissolution rate variations of about one order of magnitude. Additionally, spatiotemporal variations of BSi reactivity are supposedly related to biomineralization conditions in surface waters (Van Bennekom et al, 1991;Van Beusekom et al, 1997). Nevertheless, a consistent BSi reactivity pattern should be expected within a given oceanographic setting.…”