A budget of bioavailable inorganic phosphorus in the sediment for the western Wadden Sea

This paper provides quantitative and qualitative information on the sediment P pool for the western Wadden Sea. Total extractable P concentrations in the sediment were lower than 4 mu mol g(-1), with the exception of a depositional area of fine sediment where P concentrations reached 45 mu mol g(-1). Most P was in a non-bioavailable form, with the bioavailable inorganic fraction corresponding to 12-42% of the total extractable pool and being mainly composed of Fe-bound P. A strong negative relationship between median grain size and bioavailable inorganic P content was found based on which a budget was calculated for the periods of maximum (February/March) and minimum (November) content of bioavailable inorganic Pin the top 9 cm's of sediment. The sediment P budget decreased from 1.0 x 10(8) mol in February/March to 0.6 x 10(8) mol in November. Assuming that the seasonal difference was due to the release to the overlying water, an exchange of 4.0 x 10(7) mol of P was estimated, which has the potential to fuel approximately 40% of the current annual primary production of similar to 200 g C m(-2)