Dissolved Organic Matter dynamics in the Adriatic Sea

Vertical distribution of Dissolved Organic Carbon (DOC) and Fluorescent Dissolved Organic Matter (FDOM) was studied in the Southern Adriatic Sea in December 2015 and April 2016 (Eurofleets2-ESAW cruises). DOC showed a clear seasonality with the highest values in the mixed layer in December and a downward export due to vertical mixing in April. In the bottom layer (800- 1200 m) DOC values in April were up to 13 μM higher than in December, even if no increase in oxygen was observed. The application of PARAFAC to the 330 excitation emission matrices (EEMs) allowed for the validation of a 6-component model, indicating the occurrence of 3 terrestrial and 1 marine humic-like components, 1 protein-like and 1 PAH-like components. Fluorescence indicates removal in the upper layers and a transformation of the DOM pool in the deep waters.