DISTRIBUTION OF ALIPHATIC-HYDROCARBONS IN PLANKTON OF ADRIATIC SEA OPEN WATERS

Aliphatic hydrocarbons from n-C15 to n-C30 were determined in plankton of the Adriatic Sea open waters in order to evaluate distribution, concentration and origin of these compounds. The samples were collected in eight different stations during two cruises in spring and in summer. The results obtained enable us to divide the samples into two main groups. The first where some biogenic hydrocarbons are dominant, the second where fossil hydrocarbons prevail. The dominant biogenic hydrocarbons are: pristane, n-C17, squalene, heneicosahexaene. In spring samples the average concentrations (36.6-mu-g/g dry weight) are significatively higher than in summer samples (8.4-mu-g/g dry weight). This could be linked to the presence in spring of large amounts of recently biosynthesized hydrocarbons in the Adriatic environment or to more active physical, chemical and biochemical processes of release and degradation during the warm season.