RELATIONSHIP BETWEEN THE OPTICAL-PROPERTIES OF CHROMOPHORIC DISSOLVEDORGANIC-MATTER AND TOTAL CONCENTRATION OF DISSOLVED ORGANIC-CARBON INTHE SOUTHERN BALTIC SEA REGION

Absorption and fluorescence of chromophoric dissolved organic matter ( CDOM) and dissolved organic carbon (DOG) measurements were performed d uring three oceanographic surveys in 1994 in the southern Baltic Sea ( Polish area of the Baltic Proper). DOC was measured both by high-tempe rature catalytic oxidation (HTCO) and low-temperature oxidation (LTO) conventional persulphate methods. CDOM fluorescence was shown to be hi ghly correlated with absorption, with the same regression parameters, despite the seasonal change in different hydrographic conditions and t he fluorescence quantum yield variations (1.23+/-0.07 in April and 0.9 7+/-0.12 in September). The results show a good correlation between th e optical parameters and DOC although similar to 70% of the DOC does n ot display significant absorption in the UV-visible range (350-750 nm) . The non-absorbing DOC measured with HTCO method appears unaffected b y seasonal changes. Consequently, total DOC can be predicted by optica l methods using remote sensing techniques. The non-absorbing DOC measu red by LTO method varies from 62% (April) to 76% (September), which im plies that there is requirement for estimates on a seasonal basis.