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Hinrichs Lab - Dissolved Organic Matter

 
Dissolved organic matter (DOM) is traditionally defined as the fraction that passes through a filter of a pore size between 0.2 and 1 µm. DOM accounts for around 90% of the organic carbon in the oceans (~700 Pg C) representing one of the largest active carbon pools on earth, approximately equal to the amount of atmospheric CO2. DOM consists of a myriad of compounds with different molecule sizes, structures and properties making it an analytical challenge. The high complexity of DOM mixtures hampered an identification of individual DOM molecules and analytical approaches were restriced to the bulk level for a long time.

During the last decade ultra-high resolution techniques became accessible for organic geochemists providing more information about DOM. In particular, electrospray ionization (ESI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) enabled huge advances in the molecular characterization of DOM (Kim et al. 2003; Koch et al., 2005; Hertkorn et al., 2006). FT-ICR-MS was established in 1974 (Comisarow and Marshall, 1974) and first performance on DOM in combination with electrospray ionization (ESI) is dated to the early 2000’s (e.g., Stenson et al., 2003).


The high resolving power of the instrument enables the analyses of complex, water soluble, organic mixtures without the need of sample separation a priori. FT-ICR-MS analyses provide exact mass information of single organic matter components which can be translated into molecular formulas.
In cooperation with Bruker Daltonik GmbH (Bremen) and Prof. Dr. Boris Koch (AWI, Bremerhaven), we analyze DOM extracted from sediments which opens new perspectives and insights on source materials and transformation reactions within the organic matter (Schmidt et al. 2009, 2011).