The chemical composition of mucilage aggregates found during summer 2000, 2001 and 2002 in the North Adriatic Sea depends on the nature of the organic matter during aggregation, on the environmental conditions of the site of formation and on the transformations during ageing. The mucilages were composed of organic matter, together with a significant inorganic fraction. Elemental analysis revealed 12.5–32.2% of organic carbon, 0–7.3% of inorganic carbon and 1.0–3.7% of nitrogen. The Corg/N ratios of most aggregates were between 7.5 and 12.6, values close to those found in the suspended matter; higher ratios were found in large-size (N5 m) aggregates which are probably older. The content of carbohydrates and proteins determined in the aggregates, respectively, 15.4F8.9% and 7.9F4.8%, w/w, showed a prevalence of carbohydrates over proteins.
