EGU24-3580, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Temporal and spatial investigations of the isotope biogeochemistry of a coastal peatland area under sporadic flooding 

Rhodelyn Saban1, Anna-Kathrina Jenner1, Catia Milene Ehlert von Ahn1,4, Iris Schmiedinger1, and Michael Böttcher1,2,3
Rhodelyn Saban et al.
  • 1Leibniz Institute for Baltic Sea Research Warnemuende, Geochemistry & Isotope Biogeochemistry, Rostock, Germany (
  • 2Marine Geochemistry, University of Greifswald, Germany
  • 3Interdisciplinary Faculty, University of Rostock, Germany
  • 4Leibniz Centre for Tropical Research ZMT, Bremen, Germany

The interface between the terrestrial and marine environments regulates the interactions between the adjoining domains. Natural and anthropogenic alterations influence the processes and exchanges of materials. This study aims to determine the biogeochemical processes before and after anthropogenic changes in the coastal protection at the southern Baltic Sea coast proximal to a peatland (Hütelmoor, Rostock, Germany). Spatial and temporal investigations, with the use of stationary porewater lances, characterize the dynamics of biogeochemical transformation processes. Porewaters were measured for in-situ physico-chemical parameters and analyzed for dissolved organic and inorganic carbon (DOC and DIC), major ions, redox-sensitive elements and nutrients concentrations. Stable isotopes (ẟ13C-DIC and -DOC, ẟ2H- and ẟ18O-H2O, and ẟ34S- and ẟ18O-SO4, and ẟ34S-H2S) and non-stable isotopes (223Ra, 224Ra) were also measured. Results indicate high concentrations of DOC which may have originated from peat degradation and high concentrations of DIC, which may have been derived from organic matter mineralization, terrestrial and marine carbonate dissolution, and Baltic Sea-derived DIC. Minor contributions from CH4 oxidation cannot be ruled out. Diagenetic transformations are also reflected in the vertical profiles of redox-sensitive ions (such as Fe, Mn, SO4 and H2S). Sulfate, dominantly from Baltic Sea water and microbial reduction-oxidation, influences diagenesis. Water is a mixture of different brackish and freshwater sources.  Moreover, submarine groundwater discharge (SGD) was observed from 150 cmbsf and also evident in 224Ra activities. With the changes in the coastal protection status, internal transport processes of porewaters in the sediment are evidently influenced by the hydrogeodynamics along the coastline on a local to regional scale.

How to cite: Saban, R., Jenner, A.-K., Ehlert von Ahn, C. M., Schmiedinger, I., and Böttcher, M.: Temporal and spatial investigations of the isotope biogeochemistry of a coastal peatland area under sporadic flooding , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3580,, 2024.