engleski

Organic matter characterization and fate in the subarctic Norwegian fjords during late spring/summer period

The organic matter (OM) pool has been studied in two subarctic north Norwegian fjords, Balsfjord and Ullsfjord, in July 2001 and June 2003. Besides general OM parameters such as dissolved organic carbon (DOC), particulate organic carbon and nitrogen (POC and PON), the distribution of specific compounds such as folic acid and surface active substances (SAS) was followed. The attained results are supported with the data of salinity and temperature, and chlorophyll a (Chl a). This approach allowed to assess the fate of OM pool, and its distinct vertical, spatial, and seasonal variations. Fjord waters could be vertically divided in two layers: the upper mixed layer (UML), until 40 m depth, and the deep aphotic layer. Spatial variability between the two fjords is a consequence of different influences of shelf waters on the fjords. Significant enrichment of POC and PON concentrations (3 to 5 times), as well as those of particulate SAS and folic acid (up to 3.2 times) in the UML was recorded during the period of new production, in early June. Depletion of particulate OM in deep waters was ascribed to fast dissolution or remineralization in the UML or upper part of aphotic layer. OM in July 2001 was characterized with 15.9 % higher DOC pool compared to June 2003, and had refractory properties, suggesting the fjords to be an important source of organic matter to continental shelf ecosystem. The DOC pool in these subarctic fjords represents the major component of OM pool. Fjords DOC concentrations are lower than those in previously studied warmer seas (eg. The Adriatic Sea), whereas the concentrations of folic acid and SAS are comparable to those in the Adriatic Sea.

organic matter; folic acid; surfactant activity; subarctic fjords; Norway

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