Biogeochemical processes in sediments of the Manfredonia Gulf (Southern Adriatic Sea): early diagenesis of carbon and nutrient and benthic exchange

Abstract. In order to understand the mechanisms responsible of the recycle of carbon and nutrients at the sediment-water interface and to understand the role of sediments in nutrients mass balance in coastal water, cores were collected (pore waters and solid phases) and benthic fluxes (oxygen, dissolved nutrients, dissolved iron and managanese, alkalinity and TCO₂) were measured in two stations in the Gulf of Manfredonia (Southern Adriatic Sea). Stations were chosen to include a site, in the offshore part of the gulf, under the influence of western Adriatic current and another site, in the inner part of the gulf, under influence of gyres occurring inside the gulf. Both stations were placed in areas characterized by high sedimentation rate. Fluxes at sediment water interface show higher values in S2 site during the summer. Bio-irrigation seems to be the main transport mechanism characterizing both sites, with more evident effects during summer in S1 site.