ABSTRACT
Sediment oxygen production rates and actual oxygen concentrations can be measured directly in the sediment with oxygen microelectrodes. In bell jars, sediment oxygen production or consumption rates can be measured indirectly as the increase or decrease of oxygen concentration occurs in the enclosed overlying water column. Oxygen concentrations in sediments and in overlying water can be measured very accurately with oxygen microelectrodes. In sediments these measurements show oxygen gradients. Oxygen gradients can be used to calculate oxygen fluxes into or out of the sediment when the porosity and the diffusion coefficient are known. In bell jars or chambers, net oxygen fluxes can be derived by transforming the change of oxygen concentration in the bell jar into a flux through the sediment-water interface of the bell jar. The basic assumption in oxygen production or consumption measurements by incubations in chambers is that the rate of oxygen release or uptake is independent of the oxygen concentration in the water overlying the sediment.
