Molecular and Isotopic Characterization of DOM on the East Siberian Shelf, Arctic Ocean.
Water profiles from 51 stations, including two transects across the shelf-basin interface (water depths <40 to >2500m), were sampled during July–August. Salinity ranged from 24.7 to 34.9, and dissolved organic carbon (DOC) concentrations showed values between 46 and 312 µmol L-1. DOM was isolated from seawater by solid phase extraction (SPE). The carbon and nitrogen stable isotope ratios (δ13C and δ15N) of SPE-DOM ranged from -27.9 to -22.4‰ and -0.3 to 4.6‰, respectively. SPE-DOM was further analysed with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to investigate the DOM molecular composition and to identify degradation pathways along the gradients in salinity and DOC, for example changes in aromaticity or saturation within the DOM pool.
The presented data will largely contribute to the recent knowledge about the composition as well as the large-scale input and degradation patterns of terrestrial DOM in the Arctic Ocean.