Thorsten Dittmar

Method Development

The molecular composition of dissolved organic matter (DOM) is the key to most of the unsolved questions. For example, lignin can be used as an unambiguous tracer for terrestrial DOM in the ocean. Lignin is part of wood and other vascular material and is produced exclusively by land-plants, but not by algae. Thus, the existence of lignin in seawater is clear evidence for DOM from land. Other chemical tracers can be used in a similar fashion to identify DOM from bacteria or algae, for example amino acids.

Lignin

Molecular structure of lignin monomers.

The very low concentration of organic molecules dissolved in seawater compared to inorganic salts is a major challenge in analytical chemistry and very few analytical methods are available to date to analyze the molecular composition of DOM in seawater. In collaboration with colleagues from several research institutes I am developing new methods in order to learn more about the chemical identity of DOM in the ocean. Most promising are the latest improvements in ultrahigh-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. The collaboration involves colleagues from the Alfred Wegener Institute for Polar and Marine Research, the National High Magnetic Field Laboratory, the GSF Research Center, and the University of Washington.