A Novel Laboratory-Scale Mesocosm Setup to Study Methane Emission Mitigation by Sphagnum Mosses and Associated Methanotrophs.

Martine A R Kox,Huub J M Op Den Camp,Daan R Speth,Mike S M Jetten,Maartje A H J Van Kessel,Alfons J P Smolders,Leon P M Lamers

doi:10.3389/fmicb.2021.651103

Martine A R Kox, Huub J M Op Den Camp + Show 5 more

Open Access

https://doi.org/10.3389/fmicb.2021.651103

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Abstract

Degraded peatlands are often rewetted to prevent oxidation of the peat, which reduces CO2 emission. However, the created anoxic conditions will boost methane (CH4) production and thus emission. Here, we show that submerged Sphagnum peat mosses in rewetted-submerged peatlands can reduce CH4 emission from peatlands with 93%. We were able to mimic the field situation in the laboratory by using a novel mesocosm set-up. By combining these with 16S rRNA gene amplicon sequencing and qPCR analysis of the pmoA and mmoX genes, we showed that submerged Sphagnum mosses act as a niche for CH4 oxidizing bacteria. The tight association between Sphagnum peat mosses and methane oxidizing bacteria (MOB) significantly reduces CH4 emissions by peatlands and can be studied in more detail in the mesocosm setup developed in this study.

Highlights

About 15% of peatland area has been drained for agriculture, forestry or bioenergy production, with highest losses in Europe (Joosten and Clarke, 2002; Grootjans et al, 2012)
We developed a new mesocosm set-up (Figure 1) in which methane-oxidation by submerged Sphagnum mosses can be studied in detail in a controlled laboratory setup, without the variability encountered in the field
To estimate diffusive CH4 emissions in the field, fluxchamber measurements were conducted in plots with submerged Sphagnum mosses before and after removal of the moss layer

Summary

Introduction

About 15% of peatland area has been drained for agriculture, forestry or bioenergy production, with highest losses in Europe (Joosten and Clarke, 2002; Grootjans et al, 2012). Drainage results in the exposure of the organic peat layer to oxygen, resulting in high CO2 emission (Waddington and Day, 2007; Abdalla et al, 2016; Reumer et al, 2018). As restoration measure, drained peatlands can be rewetted to protect organic matter from fast aerobic degradation (Grootjans et al, 2012; Renou-Wilson et al, 2019). The resulting anaerobic conditions create a suitable environment for the production of the potent greenhouse gas methane (CH4), leading to high methane emissions (Harpenslager et al, 2015; Abdalla et al, 2016; Renou-Wilson et al, 2019). When the water table rises, the oxygen concentration decreases which results in a strong increase in CH4 emission (Smolders et al, 2003; Harpenslager et al, 2015)

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