Sediment respiration contributes to phosphate release in lowland surface waters.

High phosphate (PO) concentration peaks in lowland rivers occur due to internal loading at low flow rates and low dissolved oxygen (DO) concentrations. However the mechanisms controlling this PO are not fully understood yet. This study was set up to identify additional factors affecting internal P loading, the hypothesis being that sediment respiration varies among sediments and might explain spatial variability in reducing conditions.