Apparatus for the investigation of microbial reaction rates in sediment suspensions

Abstract

An apparatus is described for the determination of microbe-induced reaction rates in stirred sediment/water suspensions and material fluxes across the sediment/water interface of undisturbed sediment cores. The system consists of a closed gas loop coupled to a reaction vessel, thus maintaining an equilibrium between water and gasphase. The vessel is equipped with sensors for oxygen, pH and redox potential and with facilities for sampling. On-line gas analysis is done by gas chromatography with a sensitive helium-ionization detector. The oxygen concentration in the system is regulated by computer-controlled injection of oxygen into the gas loop. As an example, flux measurements of an undisturbed sediment core are presented and discussed.