EN
The concentration of monosaccharides in samples collected in the Gulf of Gdańsk area was determined in water filtered through ∼0.8 μm pore size filters. Seawater concentrations ranged from about 0.2 to 1.1 mg C dm−3, the highest values being detected at the mouth of the river Vistula. Seasonality was detectable in the data distribution; the majority of autumn values lay within the 0.2–0.4 range while concentrations in the spring samples were higher and the values more widely scattered. Measurements of monosaccharide concentrations at selected points during the whole observation period showed that values increased from spring to autumn as much as 5-fold. Concomitant analyses in Vistula river water yielded concentrations from 0.4 to 1.2 mg C dm−3. These latter values were all higher than those recorded in seawater in the corresponding months.