A dynamic method to determine the O₂‐partial pressure distribution within soil aggregates

Abstract

Abstract During amperometric measurements of oxygen concentration an electrode itself consumes oxygen. To make sure that oxygen concentration at a soil microsite is not lowered by the measurement itself, but determines the in situ situation, the sensitive tip of the electrode should not be in a static position for a longer time than is necessary to reach equilibrium. If the electrode is moved stepwise through the soil aggregate and is allowed to reach equilibrium at every position, it is possible to measure profiles of oxygen partial pressure distribution from the surface to the center of single soil aggregates. We used a small electromotor attached to a micromanipulator to push the pO 2 ‐sensitive microelectrode at a constant speed through the soil aggregate. As an advantage this ‘dynamic’ method needs no man power and gives continuous profiles of oxygen concentration from the surface to the center of the aggregate.