EGU2020-7314
https://doi.org/10.5194/egusphere-egu2020-7314
EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Hydrology, electron acceptor availability and organic matter decomposition in Dutch peatland pastures

Jim Boonman, Ko van Huissteden, Han Dolman, and Ype van der Velde
Jim Boonman et al.
  • Vrije Universiteit Amsterdam, Faculty of Science, Earth and Climate , Netherlands (j.boonman@vu.nl)

The Netherlands plans to cut greenhouse gas emissions by 1 megaton CO2-equivalents in 2030 by implementing measures reducing peat decomposition. In order to achieve this, a national research program on peatland pasture greenhouse gas emissions has been set up. In the program, five peatland sites with each two fields, with and without submerged tube drainage systems, are continuously monitored. Here, we present our research with the objective to understand the rate of biochemical peat decomposition by assessing electron acceptor availability from a hydrological perspective. Soil (< 100 cm depth) redox conditions are continuously measured at five depths. Preliminary data on soil electron acceptor availability distribution suggest counterintuitive behavior of the peat soils. We find reducing conditions in the topsoil (0-20 cm) and oxidative conditions in the subsoil (40-80 cm) for the sites without tube drainage. For sites with tube drainage, we find oxidative conditions in the topsoil (0-20 cm) and reducing conditions starting at 60 cm depth at the drain location and at 80 cm depth between the drains. A novel 2D groundwater model is being set up, enabling to capture saturation dynamics, water origin and solute transport in the peat soil. We will present our modelling setup and initial simulation results for water origin and travel paths. These results will indicate how electron acceptors are distributed through the soil, helping to interpret redox measurements in the field at different depths. In a later stage of the research, the effects of redox conditions on microbial soil respiration will be evaluated with greenhouse gas chamber and eddy covariance measurements.

How to cite: Boonman, J., van Huissteden, K., Dolman, H., and van der Velde, Y.: Hydrology, electron acceptor availability and organic matter decomposition in Dutch peatland pastures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7314, https://doi.org/10.5194/egusphere-egu2020-7314, 2020

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  • CC1: Comment on EGU2020-7314, Merten Minke, 07 May 2020

    Dear Jim,

    thank you for the exciting presentation. Your first hypothesis is that water flow itself increases peat oxidation. This is very interesting and reminds me on the concept of rheotrophy. But this would mean, that subsurface irrigation, while aiming at reducing decomposition, is in fact increasing it. Do you think, this may indeed be possible?

    Best wishes

    Merten

    • AC1: Reply to CC1, Jim Boonman, 07 May 2020

      Dear Merten,

      Thank you for your comment and interst in the research.  I must say that I am not familiar with rheotrophy yet (and am not able to find a definition). 

      Of couse, this is only a hypothesis. However, we indeed are not completely certain of the effect of submerged drainage. Decomposition could be enchanced due to an increased discharge of waste products from decomposition, and higher input rate of electron acceptors and reactants. We think that the quality of the inflow drain water will also have an impact on decomposition (i.e. high oxygen or nitrate levels in inflow drain water could enhance subsoil decomposition). In addition we expect DOC to leach from the soil earlier during wet conditions, through the drain system, possibly enhancing organic decomposition.  There will be many more factors related to microbial activity, but we try to look at it from this perspective.

      We are very curious about the total balance, the differences we will observe during the summertime and if we could relate modelled groundwater flows to the observed CO2 emissions.  

      Best,
      Jim
       

      • CC2: Reply to AC1, Merten Minke, 08 May 2020

        Dear Jim,

        "Rheotrophie" is mentioned by Edom, F. (2001) as the increase of ion supply to plants by flowing water, i.e. they receive more ions as compared to stagnant water. According to Edom this concept goes back to Kulczynski, S. (1949) . I just have checked it in the "Peat bogs of Polesie" (Kulczynski, 1949) and found the termin "rheophilous peat bogs". Kulczynski writes "The mode in which water flowing through a peat-bog affects the bog flora can be best characterised in E. Ramann's words (Ramann 1932, p. 179): "Flowing water acts like an increase of nutrient content, stagnant water like a decrease." Flowing water constantly brings fresh mineral nutrients to the bog, and this leads to the development of a eutrophic valley-bog flora, ... Water mobility also increaes the oxygen supply of a bog, and consequently it exerts an influence on the life of the microflora, and on the dircection of biological and chemical processes of decay in a bog, and also, as an ultimate result, on peat acidity."

        Best wishes

        Merten

         

        • AC2: Reply to CC2, Jim Boonman, 11 May 2020

          Dear Merten,

          Thank you for the inspiring references and citations. I agree that the definition of rheotrphy fits the hypothesis (although ‘plants’ should be interchanged for ‘microbes’). I will definitely try to integrate it in the research. Furthermore, I will keep you updated on our findings!

          Best regards,

          Jim