The release of phosphorus during sediment resuspension

where: Km = mass transfer coefficient (m/s), Cb = parameter representing a characteristic SRP concentration in the pore water (mmol/m 3), Co = concentration in the water column (mmol/m 3). The annual variation and the differences between the 5 stations concerning fluxes and underlying parameters (Kin, Cb) are discussed and the ecological interpretation is indicated. Factors included are e.g. overall mineralization activity (oxygen respiration), oxygen penetration depth, Fe contents of the sediments, abundance of macrofauna, influence of benthic diatoms. To enable this analysis data on SRP pore water concentrations and results of sequential extractions according to the Hieltjes-Lijklema scheme are presented also. In addition, experiments were performed to measure sorption characteristics (isotherms, kinetics) of the upper 5 mm of the Wadden Sea sediments. Results of these will be related to the data of the extractions. Integration of all results is done by simple models based on general early diagenesis modelling concepts, leading to a further parameterization of the above flux equation. In this parameterization K is a function of e.g. diffusion, sorption kinetics, oxygen penetration depth and macrofauna abundance (bio-irrigation), and Cb is determined by mineralization rate, aerobic sorption isotherms and kinetics, anaerobic reaction characteristics etc. Finally benthic phosphorus exchange rates as observed in both North Sea and Wadden Sea are evaluated according to the models.