AN EVALUATION OF PHOSPHATE UPWARD FLUXES FROM THE COASTAL SEDIMENTS BY 3 DIFFERENT METHODS

The upward fluxes of phosphate across the overlying water-sediment int erface were evaluated by three different methods. In method I, the flu xes were estimated from vertical profiles of interstitial phosphate co ncentrations, followed by the diagenetic model (Fick's law). Measurmen t of fluxes in method II was based on the changes in phosphate concent rations of overlying water in the core tubes incubated under simulated in situ dissolved oxgen conditions, and in method III, phosphate rele ase was measured during the incubation of overlying water with surface sediments in glass bottles under dark conditions at three different t emperatures. The fluxes determined by these three methods agreed well with each other. It was considered that during the summer period, in s itu fluxes in our study area might reach almost the potential level. M oreover, it was evident that the flux was influenced by ambient temper ature under anaerobic condition.