Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols

[摘要] Atmospheric aerosols impose direct and indirect effects on the climatesystem, for example, by absorption of radiation in relation to clouddroplets size, on chemical and organic composition and cloud dynamics. Thefirst step in the formation of Organic primary aerosols, i.e. the transferof dissolved organic matter from the marine surface into the atmosphere, wasstudied. We present a molecular level description of this phenomenon usingthe high resolution analytical tools of Fourier transform ion cyclotronresonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonancespectroscopy (NMR). Our experiments confirm the chemoselective transfer ofnatural organic molecules, especially of aliphatic compounds from thesurface water into the atmosphere via bubble bursting processes. Transferfrom marine surface water to the atmosphere involves a chemical gradientgoverned by the physicochemical properties of the involved molecules whencomparing elemental compositions and differentiating CHO, CHNO, CHOS andCHNOS bearing compounds. Typical chemical fingerprints of compounds enrichedin the aerosol phase were CHO and CHOS molecular series, smaller moleculesof higher aliphaticity and lower oxygen content, and typical surfactants. Anon-targeted metabolomics analysis demonstrated that many of these moleculescorresponded to homologous series of oxo-, hydroxy-, methoxy-, branchedfatty acids and mono-, di- and tricarboxylic acids as well as monoterpenesand sugars. These surface active biomolecules were preferentiallytransferred from surface water into the atmosphere via bubble burstingprocesses to form a significant fraction of primary organic aerosols. Thisway of sea spray production leaves a selective biological signature of thesurface water in the corresponding aerosol that may be transported intohigher altitudes up to the lower atmosphere, thus contributing to theformation of secondary organic aerosol on a global scale or transportedlaterally with possible deposition in the context of global biogeocycling.

[学科分类] 地球化学与岩石