Control mechanisms on the reactive silicate fluxes by using on board resuspension experiments in the eutrophicated coastal environment

This study aims to differentiate bio-mediated and biogenic CO(3)(-2)precipitation or terrestrial CO3-2 input using onboard incubation techniques,to investigate the effects of resuspension in the coastal environment andto increase our understanding of predicted relationships between silicatereleases and other biogeochemical variables in resuspension events.Relationships between dark silicate flux and BSi, CO3-2, OrgC, Mn (manganese)according to the seasons were examined. The silica flux is controlled by theCaCO(3) coating on the diatom skeletons due to the fact that diatom skeletonsact as crystallization nuclei in the calcite precipitation that is biologicallyaffected. The reduction in flux with BSi may be due to the reduction in thesurface areas of larger diatom species. The negative linear relationshipsobserved between silica fluxes and CO3-2 is indicative of RSi fluxes constrainedby bio-mediated carbonate increase. Linear relationships which are the samein their slopes but differ in their intercepts, reveal the effect of the changein diatom size on silica flux. Smaller diatoms have more surface area perunit volume, meaning an increased silica flux. On the other hand, seeingdifferent CO(3)(-2)values at stations with the same orgC value have increasedthe confidence interval (CI) 95% in the linear relationship. The presence ofdifferent silica flux values in stations with the same carbonate value may beexplained both by different orgC values and by diatoms containing differentgroup sizes. The silica flux is controlled by the CaCO3 coating on the diatomskeletons due to the fact that diatom skeletons act as crystallization nucleiin the calcite precipitation that is biologically affected. The main mechanismcontrolling the reactive silica flux is carbonate precipitation. The observationof different silica flux values in stations with the same carbonate values canalso be explained by OrgC