Investigation of the decay of DOM fraction in soils with different vegetation types by fluorescence and 2D-correlation spectroscopy
- 1Geographical Institute, Research Centre for Astronomy and Earth Sciences, ELKH, Budaörsi út 45, H-1112 Budapest, Hungary
- 2Department of Environmental and Landscape Geography, Eötvös Loránd University, Pázmány Péter sétány 1/C, H-1117 Budapest, Hungary
- 3Institute of Geography and Geoinformatics, University of Miskolc, Building A4, Miskolc-Egyetemváros, H-3515 Miskolc, Hungary
Dissolved organic matter (DOM) fraction of four soils with different vegetation types (grassland, spruce, oak, agricultural) were incubated at 15 °C and the chemical changes of organic matter were monitored by synchronous fluorescence and 2D-correlation spectroscopy. Fluorescence spectroscopy revealed that at the beginning of incubation, on day 3, the proportion of low molecular weight readily biodegradable compounds increases, and from day 8 onwards, the initiated microbial degradation generates a large number of medium molecular weight molecules. At further samplings (days 21, 35 and 60), the proportion of compounds of microbial origin decreases systematically, due to a decrease in microbial activity caused by the lack of substrate. In 2D correlation measurements, we found that the temporal change in spectral ranges was as follows: 250 → 290 → 360 nm. This provides spectroscopic evidence that microorganisms start to consume low molecular weight peptide or sugar-like substances and then release organic matter into the environment through their death and metabolism. At a later stage of incubation, they start to break down the higher molecular weight fulvic acid-like molecules.
We concluded that (i) similar patterns emerged in the spectral features of degradation for the four different soils: the dynamics of organic molecules with different size ranges were the same, (ii) a general scheme was found during the decomposition: microorganisms begin to break down the low-molecular-weight organic substances, and then, through their death and metabolism, release organic substances into their environment; finally, in the later stages of mineralization, the higher molecular weight, fulvic acid-like molecules are degraded and (iii) 2D-correlation spectroscopy has proven to be an effective tool for monitoring chemical changes in dissolved organic matter, revealing both simultaneous and sequential chemical events.
This work was supported by the Development and Innovation Fund of Hungary [grant No. NKFIH 132191].
How to cite: Filep, T., Zacháry, D., Ringer, M., Jakab, G., and Szalai, Z.: Investigation of the decay of DOM fraction in soils with different vegetation types by fluorescence and 2D-correlation spectroscopy, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5437, https://doi.org/10.5194/egusphere-egu23-5437, 2023.
