Coastal marine regions such as the Gulf of Trieste (GOT) in the Northern Adriatic Sea serve as the link between carbon cycling on land and the ocean interior and potentially contribute large uncertainties in the estimate of anthropogenic CO2 uptake. This system may be either a sink or a source for atmospheric CO2. Understanding the sources and sinks as a result of biological and physical controls for air-sea carbon dioxide fluxes in coastal waters may substantially alter the current view of the global carbon budget.GOT is a semi-enclosed Mediterranean basin in the northern Adriatic Sea. It is one of the most productive regions in the Mediterranean and is affected by extreme fresh river input, phytoplankton blooms, and large changes of air-sea exchange during Bora high wind events. The unique combination of these environmental processes and relatively small size of the area makes the region an excellent study site for investigations of air-sea interaction, and changes in biology and carbon chemistry. However, there is a dearth of current data from the region.The aim of this project is to collect the first set of carbonate measurements from the region to determine whether GOT is a sink or source for atmospheric CO2, and to quantify the effect of the extreme fresh water input, phytoplankton blooms, and high wind Bora events on the carbon cycle in the area. The proposed project will start an intensive carbon study for this new territory with the unique environmental conditions. It will advance our understanding of the role of the coastal ocean in the global carbon cycle and the global integration of air-sea CO2 fluxes, by: 1) providing new data from the area where currently no such information is available; 2) elucidating new insides on unique features of GOT, a heavily urbanized region with extreme environmental conditions controlling air-sea flux of CO2; and 3) providing relevant information for other larger coastal areas of current interest for CO2 studies.