The role of sedimentary biogeochemistry in the formation of hypoxia in shallow coastal waters (Gulf of Trieste, northern Adriatic)

Pore water measurements of dissolved organic matter (DOM) and inorganic nutrients in the surficial sediment of the Gulf of Trieste showed the highest concentrations to be in late summer due to the higher microbial activity and restricted upward fluxes to the overlying water because of density stratification in the water column. The benthic fluxes of DOM, in terms of dissolved organic carbon (DOC), nitrogen (DON) and phosphorus (DOP), and the inorganic nutrients NH₄ ⁺ and PO₄ ^3-, measured in parallel with sediment oxygen consumption (SOC) and production, showed in general a net influx indicating benthic consumption. Only strong DOC fluxes out of the sediment prevail in late summer. -from Authors