engleski

Organic matter characterization in the sea surface microlayers in the subarctic Norwegian fjords region

The top of the ocean, sea surface microlayer (ML), covers more than 70% of the world's surface. It is a sink for natural and anthropogenic material that depends on its chemical composition. This article is aimed at providing novel data on the characterization of organic matter in ML and underlying waters (ULW) in the rarely investigated subarctic, north Norwegian fjords region, in July 2001, August 2002 and June 2003. A multiparameter approach was used, including DOC measurements, characterization of surface active organic substances (SAS), determination of Cu complexing capacity (LT) and specific analysis of fatty acids (FA). The characteristics of organic matter in fjords' sea surface microlayers showed that organic substances in the films were mainly produced in the subsurface water. There was negligible fractionation of hydrophobic substances to the microlayer and even depletion of fatty acids was found in some ML samples. Fjords' surface waters were found to be very rich in fatty acids in July, up to 201 μ g/l, with high contributions of polyunsaturated compounds. The enrichment of DOC and SAS concentrations in ML as compared to the ULW was in the range of 1.2– 2.8, while higher enrichment factors (1.3– 5.1) were determined for copper complexing ligands, indicating increased contribution of hydrophilic, lower molecular weight molecules. The detected characteristics and concentrations of organic substances in the surface microlayer and adjacent subsurface water were dependent on the month of sampling.

sea surface microlayer; organic matter; fatty acids; Cu complexing capacity; surfactant activity; subarctic fjords; Norway

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