Fatty acid concentrations in sandy dune soils : [research data]

Not much is known about the initial soil organic matter (SOM) development in coastal dunes, but such knowledge may open up a window into the first phases of soil genesis and organic C-compound stabilization. Therefore, we investigated two temperate dune transects along a geomorphological succession gradient at the Baltic Sea coast by two mass spectrometric methods that determined the proportions of biogenic compound classes (Pyrolysis-Field Ionization Mass Spectrometry; Py-FIMS) and the concentrations of saturated and unsaturated n-alkyl acids (Gas Chromatography/Mass Spectrometry; GC/MS) in soil samples and biological soil crusts (biocrusts, at the oldest soil profiles only). Landward along the transect the proportions of lipids, suberin, and free fatty acids increased with dune development. Furthermore, within the group of extracted lipids, the concentrations and the chain lengths of n-alkyl fatty acids increased as well and reached the maximum values in the mature dune samples, although smaller by factors of two to four than in the corresponding biocrust samples from the topsoil surface. We propose two major organic C-compound stabilization mechanisms effective in the very early pedogenesis in these dune sands (1) complexation of lignin dimers by newly formed pedogenic Fe-oxides and (2) steric bonds of alkyl-C-compounds by quartz grains.