Natural organic matter and humic acids fractions from sediments sampled along a transect from the mainland (river) to the center of a Northern Adriatic lagoon (open lagoon and a fish farm) were analysed for their elemental composition and carbon isotope composition (δ13C),and characterized by Fourier transform infrared spectroscopy (FT-IR). Both the elemental composition and the carbon isotope composition differentiated the three environments, in particular the organic matter of the fish farm shows the most evident signs of marine origin
