AUTHOR=Mostovaya Alina , Hawkes Jeffrey A. , Dittmar Thorsten , Tranvik Lars J. TITLE=Molecular Determinants of Dissolved Organic Matter Reactivity in Lake Water JOURNAL=Frontiers in Earth Science VOLUME=5 YEAR=2017 URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2017.00106 DOI=10.3389/feart.2017.00106 ISSN=2296-6463 ABSTRACT=
Lakes in the boreal region have been recognized as the biogeochemical hotspots, yet many questions regarding the regulators of organic matter processing in these systems remain open. Molecular composition can be an important determinant of dissolved organic matter (DOM) fate in freshwater systems, but many aspects of this relationship remain unclear due to the complexity of DOM and its interactions in the natural environment. Here, we combine ultrahigh resolution mass spectrometry (FT-ICR-MS) with kinetic modeling of decay of >1,300 individual DOM molecular formulae identified by mass spectrometry, to evaluate the role of specific molecular characteristics in decomposition of lake water DOM. Our data is derived from a 4 months microbial decomposition experiment, carried out on water from three Swedish lakes, with the set-up including natural lake water, as well as the lake water pretreated with UV light. The relative decay rate of every molecular formula was estimated by fitting a single exponential model to the change in FT-ICR-MS signal intensities over decomposition time. We found a continuous range of exponential decay coefficients (