Temporal and Spatial Variability of Dissolved Organic Matter Chemistry in the Northern Barents Sea Using UPLC-ESI-HRMS

This study shows the characterization of solid phase extracted Dissolved Organic Matter (SPE-DOM) in the Northern Barents Sea and adjacent Nansen basin during summer, winter and spring sampling. Oceanic dissolved organic matter (DOM) is one of the largest reactive carbon reservoirs (~760Pg C) on earth [1] and plays an active role in the global cycling of carbon and particularly higher latitude regions play an important role in long-term carbon sequestration of atmospheric carbon but the composition of these complex mixtures is poorly characterized [2]. A total of 124 SPE-DOM samples are collected during three seasons (August & December 2019 and April 2020) at seven stations and three depths (surface, mid, deep). SPE-DOM composition results will elucidate prevalent DOM fractions (i.e. recalcitrant, labile, semi-labile) and their seasonal variability in the Northern Barents Sea using Van Krevelen plots and degree of oxidation. Related environmental parameters such as Particulate organic carbon (POC), inorganic nutrients, total dissolved nitrogen (TDN), temperature and salinity are also measured. C/N molar ratio values will give insight into spatial distribution of nitrogen functional groups in addition to terrestrial and marine DOM fractions in this region. The present study offers an alternative and more cost-effective analytical method through UPLC-ESI-HRMS which minimizes ion suppression present in widely used direct infusion methods such as FT-ICR-MS. Subsequently, this study can provide further insights into DOM fractions in the Arctic under global changes. This work is funded by the Research Council of Norway through the project, The Nansen Legacy.

[1] Hedges, J.I., Marine Chemistry, 1992. 39(1-3): p. 67-93. [2] Hansell, D.A. and C.A. Carlson, 2014: Academic Press.