Oxygen uptake kinetics in the benthic boundary layer

Abstract

A simple, one-dimensional, transport-reaction model of oxygen uptake by sediments during incubation experiments assumes zero-order reaction kinetics for oxygen removal in the pore water of sediments and takes the apparent diffusive limitation posed by the benthic boundary layer into account. Model calculations are in excellent agreement with experimental data obtained during in situ benthic flux chamber experiments in Gullmarsfjorden, Sweden, during fall (water temp, 10°C) and winter (-1'C). The boundary layer "resistance," represented by a mean diffusive sublayer thickness, was estimated with a series of radioactive tracers. The oxygen uptake curve was initially approximately linear but became exponential below -100 PM oxygen. The half-removal time of oxygen below 100 PM corresponds to a boundary layer resistance similar to that obtained with the radiotracers. The nearly constant rate of decrease of oxygen during the initial phase of the incubations suggests that incubation techniques can be used to obtain an approximate measure of the oxygen uptake rate of sediments as long as the concentration remains above the transition where the curve changes from approximately linear to exponential. This procedure, however, underestimates the oxygen uptake rate by 28-34% compared to model results. Model calculations also suggest that oxygen uptake rates can differ substantially between chamber and outside sediments, especially when hydrodynamic conditions influencing the apparent boundary layer resistance are different within and outside chambers.

Critical events in the Ariake Bay ecosystem: Clam population collapse, red tides, and hypoxic bottom water

“…However, it tends to be reduced and released to the overlying water on the sediment or the interstitial water of the sediment as manganese ion by the bacterial activity in the sediment particularly during the warm seasons when bacterial activity is accelerated (Hunt & Kelly 1988). In hypoxic water, manganese ion tends to be released intensively from the sediment (Hall et al 1989, Gerringa 1991, Baden et al 1994. Manganese is harmless in manganese dioxide, whereas manganese ion or its organically bound form is more bioavailable and excessive concentrations are neurotoxic to gastropods (Chemeris et al 1982) and to clams (Beirao 1989).…”

Multivariate benthic ecosystem functioning in the Arctic – benthic fluxes explained by environmental parameters in the southeastern Beaufort Sea

“…Incubations were stopped when oxygen levels had decreased by more than 20 % to avoid hypoxic conditions and biogeochemical transformations. Hall et al (1989) demonstrated the importance of maintaining the O 2 supply to obtain consistent and relevant data during core incubations.…”

Modeling of dissolved oxygen levels in the bottom waters of the Lower St. Lawrence Estuary: Coupling of benthic and pelagic processes

“…Enhanced diffusive transport, due to the mixing of pore waters by small organisms (meiofauna and microzoobenthos), has been proposed (Archer and Devol, 1992;Meile et al, 2001; to explain discrepancies between SOD estimates derived from in-situ benthic chamber measurements (e.g. Hall et al, 1989) /lmol cm-2 y{l, usually in shallower coastal settings), molecular diffusion underestimates the oxygen fluxes (Jahnke, 2001;. Our modeling results largely agree with this observation, as the sediment DO profiles in a region with low SOD (i.e., the GSL) are reproduced very well by our simple diagenetic model (Fig.…”