An experimental approach to quantify biologically mediated dissolved silicate transport at the sediment-water interface

Fluxes of dissolved silicate (diss. Si) across the sediment-water interface were measured by incubating cores from the Bay of Fundy, Canada, and the Dutch Wadden Sea. The influence of infauna on diss. Si transport was estimated by inactivation of infauna with formalin poisoning and 'asphyxiation'. Release of diss. Si in the Bay of Fundy ranged from 2.2 to 6.9 mmol Si m⁻² d⁻¹ (temp. 18 to 22 °C) before, and from 0.7 to 2.5 mmol m⁻² d⁻¹ after fauna-inactivation. In the Dutch Wadden Sea these data were –1.2 to 21.3 and –0.05 to 9.7 mmol diss. Si m⁻² d⁻¹ (temp. 13.5 to 20 °C), respectively. Effect of formalin-poisoning and 'asphyxiation' compared well. With only one exception fluxes of diss. Si after inactivation of sediment fauna approached, within a factor of 2, fluxes calculated from pore-water gradients by assuming that molecular diffusion is the only transport mechanism for diss. Si exchange.