Evaluating alternative ebullition models for predicting peatland methane emission and its pathways via data–model fusion

Ma, Shuang; Jiang, Lifen; Wilson, Rachel M.; Chanton, Jeff P.; Bridgham, Scott; Niu, Shuli; Iversen, Colleen M.; Malhotra, Avni; Jiang, Jiang; Lu, Xingjie; Huang, Yuanyuan; Keller, Jason; Xu, Xiaofeng; Ricciuto, Daniel M.; Hanson, Paul J.; Luo, Yiqi

doi:https://doi.org/10.5194/bg-19-2245-2022

Articles | Volume 19, issue 8

https://doi.org/10.5194/bg-19-2245-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-19-2245-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 8

Research article

|

27 Apr 2022

Research article |

| 27 Apr 2022

Evaluating alternative ebullition models for predicting peatland methane emission and its pathways via data–model fusion

Shuang Ma, Lifen Jiang, Rachel M. Wilson, Jeff P. Chanton, Scott Bridgham, Shuli Niu, Colleen M. Iversen, Avni Malhotra, Jiang Jiang, Xingjie Lu, Yuanyuan Huang, Jason Keller, Xiaofeng Xu, Daniel M. Ricciuto, Paul J. Hanson, and Yiqi Luo

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Final revised paper (published on 27 Apr 2022)
Supplement to the final revised paper
Preprint (discussion started on 20 Dec 2021)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on bg-2021-316', Anonymous Referee #1, 21 Jan 2022

This study compared two algorithms of peatland methane ebullitive fluxes and examined the impact of data availability on simulation reliability. The EBG algorithm was found to be more accurate than the ECT in simulating both methane fluxes and pore water methane concentrations. Using both methane fluxes and pore methane concentrations in parameter calibration led to better constrained parameter values. Overall, the paper is well-written, and the experiments are solid. The conclusions can be potentially helpful for methane modelers. However, there remain doubts in the motivation and aim of the study, and more information and clarifications are needed regarding the methods and the data analysis.

Major comments

How available are pore water methane concentration measurements in wetland sites generally? More observations would always help to better constrain parameter values and obtain more accurate simulation results, but if such variables are quite rare or hard to be measured, how will the finding inform other modelers on how to improve their model performances?

L31: This sentence could be misleading since the paper didn’t actually investigate the relative contributions of each pathway but only presented the modeled results which were not validated against measurements.

Table 1: Why did you select growing season only? How long did each measurement last?

What does the ‘CH4 fluxes’ include here (from ebullition only)? Since ebullition is quite spatially heterogeneous, how many observation sites were deployed at the same time?

Eq 1: Why were fstp, fph, fred not calibrated? Did you do any sensitivity tests to determine what parameters to calibrate?

Method: More information about the modeling approach is needed. How was the model structured horizontally? For how long and with what time step were the models run? What was the spin-up period? How did you deal with data with different frequency and time span for model calibration?

Table 4: Is there a quantitative criterion of well and poorly-constrained parameters? Why do you choose mean+-sd instead of median and q1-q3? For Figure 2 e,f, the posterior distributions of EBG-F are skewed so mean+-sd may reflect a wide range but the values are still relatively concentrated. However, you claim the parameter values of EBG-F in these two figures to be poorly constrained, which doesn’t seem to be a fair judgement.

Figure 4: How does Tveg affect the uncertainty range of ECT?

L440: As mentioned in Introduction, the ECT is assumed to overestimate ebullition, which is the opposite of the finding here. This needs more explanation.

Minor comments

Figure 4: the legend for observations should be dots with ranges.

Citation: https://doi.org/10.5194/bg-2021-316-RC1
- AC2: 'Reply on RC1', Shuang Ma, 11 Mar 2022
  
  Dear Editor Ito and reviewers,
  
  Thank you for reviewing our manuscript “Evaluating alternative ebullition models for predicting peatland methane emission and its pathways via data-model fusion”. We are very appreciative of the time and effort that you have spent in improving our manuscript.
  
  We have carefully gone through reviewers’ comments and have responded to their concerns and suggestions, which we believe have greatly improved our paper. Please find our detailed responses attached.
  
  Please let us know if you need any further information or clarifications.
  
  Yours truly,
  
  Shuang Ma, Ph.D.
  
  Postdoctoral Scholar
  
  Jet Propulsion Laboratory at Caltech
  
  Telephone: +1 8183542113
  
  Email: shuang.ma@jpl.nasa.gov
  
  Citation: https://doi.org/10.5194/bg-2021-316-AC2
- AC3: 'References used in replies to reviewers' comments', Shuang Ma, 11 Mar 2022
  
  Krüger, M., Eller, G., Conrad, R., & Frenzel, P. (2002). Seasonal variation in pathways of CH4 production and in CH4 oxidation in rice fields determined by stable carbon isotopes and specific inhibitors. Global Change Biology, 8(3), 265–280. https://doi.org/https://doi.org/10.1046/j.1365-2486.2002.00476.x
  Happell, J. D., Chanton, J. P., Whiting, G. J., & Showers, W. J. (1993). Stable isotopes as tracers of methane dynamics in Everglades marshes with and without active populations of methane oxidizing bacteria. Journal of Geophysical Research: Atmospheres, 98(D8), 14771–14782. https://doi.org/https://doi.org/10.1029/93JD00765
  Hodgkins, S. B., Chanton, J. P., Langford, L. C., Mccalley, C. K., Saleska, S. R., Rich, V. I., et al. (2015). Soil incubations reproduce field methane dynamics in a subarctic wetland. Biogeochemistry, 126(1), 241–249. https://doi.org/10.1007/s10533-015-0142-z
  Wilson, R. M., Tfaily, M. M., Kolton, M., Johnston, E. R., Petro, C., Zalman, C. A., et al. (2021). Soil metabolome response to whole-ecosystem warming at the Spruce and Peatland Responses under Changing Environments experiment, 118(25), 1–11. https://doi.org/10.1073/pnas.2004192118
  Holmes, M. E., Chanton, J. P., Tfaily, M. M., & Ogram, A. (2014). Global Biogeochemical Cycles. https://doi.org/10.1002/2014GB004951.Received
  Hines, M. E., Duddleston, K. N., Rooney-Varga, J. N., Fields, D., & Chanton, J. P. (2008). Uncoupling of acetate degradation from methane formation in Alaskan wetlands: Connections to vegetation distribution. Global Biogeochemical Cycles, 22(2), 1–12. https://doi.org/10.1029/2006GB002903
  Walter, K. M., Chanton, J. P., Chapin, F. S., Schuur, E. A. G., & Zimov, S. A. (2008). Methane production and bubble emissions from arctic lakes: Isotopic implications for source pathways and ages. Journal of Geophysical Research: Biogeosciences, 113(3). https://doi.org/10.1029/2007JG000569
  Chanton, J. P., Glaser, P. H., Chasar, L. S., Burdige, D. J., Hines, M. E., Siegel, D. I., et al. (2008). Radiocarbon evidence for the importance of surface vegetation on fermentation and methanogenesis in contrasting types of boreal peatlands. Global Biogeochemical Cycles, 22(4), 1–11. https://doi.org/10.1029/2008GB003274
  Keller, J. K., Weisenhorn, P. B., & Megonigal, J. P. (2009). Humic acids as electron acceptors in wetland decomposition. Soil Biology and Biochemistry, 41(7), 1518–1522. https://doi.org/10.1016/j.soilbio.2009.04.008
  Itoh, M., Ohte, N., Koba, K., Sugimoto, A., & Tani, M. (2008). Analysis of methane production pathways in a riparian wetland of a temperate forest catchment, using δ13C of pore water CH 4 and CO2. Journal of Geophysical Research: Biogeosciences, 113(3), 1–16. https://doi.org/10.1029/2007JG000647
  Verry, E. S., Brooks, K. N., Nichols, D. S., Ferris, D. R. & Sebestyen, S. D. Watershed Hydrology, in Peatland Biogeochemistry and Watershed Hydrology at the Marcell Experimental Forest (eds Kolka, R. K. et al.) 193–212 (CRC Press, Boca Raton, FL, 2011).
  Liang, J., Xia, J., Shi, Z., Jiang, L., Ma, S., Lu, X., et al. (2018). Biotic responses buffer warming-induced soil organic carbon loss in Arctic tundra. Global Change Biology, 24(10), 4946–4959. https://doi.org/doi:10.1111/gcb.14325
  Luo, Y., Ahlström, A., Allison, S. D., Batjes, N. H., Brovkin, V., Carvalhais, N., Chappell, A., Ciais, P., Davidson, E. A., Finzi, A., et al. (2016), Toward more realistic projections of soil carbon dynamics by Earth system models, Global Biogeochem. Cycles, 30, 40– 56, doi:10.1002/2015GB005239.
  Xu, T., White, L., Hui, D., & Luo, Y. (2006). Probabilistic inversion of a terrestrial ecosystem model: Analysis of uncertainty in parameter estimation and model prediction. Global Biogeochemical Cycles, 20(2), 1–15. https://doi.org/10.1029/2005GB002468
  
  Citation: https://doi.org/10.5194/bg-2021-316-AC3
RC2:
'Review of "Evaluating alternative ebullition models for predicting peatland methane emission and its pathways via data-model fusion" by Ma et al.', Anonymous Referee #2, 09 Feb 2022

In their manuscript "Evaluating alternative ebullition models for predicting peatland methane emission and its pathways via data-model fusion", Shuang Ma and co-authors present their evaluation of two different formulations of the ebullition process in methane components for Land Surface Models, the

Ebullition Bubble Growth approach and the Ebullition Concentration Threshold approach. They evaluate these approaches against methane flux and concentration measurements from the SPRCUE site using an MCMC approach and find that the Ebullition Bubble Growth model is far superior.

The authors make a very convincing argument why the Ebullition Bubble Growth approach is superior, which solves one of the many issues that need to be addressed in making methane emission models more reliable.

I am very much impressed by the manuscript. It is superbly written and about ready for publication as it is, though I have found a (very) few minor details. I really must congratulate the authors, as I've never before seen a manuscript that was as good as this during the first round of reviews.

As mentioned above, the manuscript is nearly ready for publication, but there are a few minor things to be sorted out:

- Lines 160-162: Double "in this study" -- please remove one.

- Lines 181-183: Sentence starting with "Samples shallower than..." sounds slightly awkward, I suggest rephrasing it

- Line 357: I don't see any blue shaded areas in the plot, I only see blue lines. Reformulate.

- Line 452: The model is called ELM_SPRUCE, I assume, not ELS-SRUCE, as is written?

- Line 455: "...concentrations ... was still not...". Noun is plural, verb is singular. Better use "were" instead of "was".

Citation: https://doi.org/10.5194/bg-2021-316-RC2
- AC1: 'Reply on RC2', Shuang Ma, 10 Mar 2022
  
  Dear Editor Ito and reviewers,
  Thank you for reviewing our manuscript “Evaluating alternative ebullition models for predicting peatland methane emission and its pathways via data-model fusion”. We are very appreciative of the time and effort that you have spent in improving our manuscript.
  We have carefully gone through reviewers’ comments and have responded to their concerns and suggestions, which we believe have greatly improved our paper. Please find our detailed responses attached in blue underlined fonts.
  Please let us know if you need any further information or clarifications.
  Yours truly,
  
  Shuang Ma, Ph.D.
  Postdoctoral Scholar
  Jet Propulsion Laboratory at Caltech
  Telephone: +1 8183542113
  Email: shuang.ma@jpl.nasa.gov
  
  Citation: https://doi.org/10.5194/bg-2021-316-AC1
- AC4: 'References used in replies to reviewers' comments', Shuang Ma, 11 Mar 2022
  
  Krüger, M., Eller, G., Conrad, R., & Frenzel, P. (2002). Seasonal variation in pathways of CH4 production and in CH4 oxidation in rice fields determined by stable carbon isotopes and specific inhibitors. Global Change Biology, 8(3), 265–280. https://doi.org/https://doi.org/10.1046/j.1365-2486.2002.00476.x
  Happell, J. D., Chanton, J. P., Whiting, G. J., & Showers, W. J. (1993). Stable isotopes as tracers of methane dynamics in Everglades marshes with and without active populations of methane oxidizing bacteria. Journal of Geophysical Research: Atmospheres, 98(D8), 14771–14782. https://doi.org/https://doi.org/10.1029/93JD00765
  Hodgkins, S. B., Chanton, J. P., Langford, L. C., Mccalley, C. K., Saleska, S. R., Rich, V. I., et al. (2015). Soil incubations reproduce field methane dynamics in a subarctic wetland. Biogeochemistry, 126(1), 241–249. https://doi.org/10.1007/s10533-015-0142-z
  Wilson, R. M., Tfaily, M. M., Kolton, M., Johnston, E. R., Petro, C., Zalman, C. A., et al. (2021). Soil metabolome response to whole-ecosystem warming at the Spruce and Peatland Responses under Changing Environments experiment, 118(25), 1–11. https://doi.org/10.1073/pnas.2004192118
  Holmes, M. E., Chanton, J. P., Tfaily, M. M., & Ogram, A. (2014). Global Biogeochemical Cycles. https://doi.org/10.1002/2014GB004951.Received
  Hines, M. E., Duddleston, K. N., Rooney-Varga, J. N., Fields, D., & Chanton, J. P. (2008). Uncoupling of acetate degradation from methane formation in Alaskan wetlands: Connections to vegetation distribution. Global Biogeochemical Cycles, 22(2), 1–12. https://doi.org/10.1029/2006GB002903
  Walter, K. M., Chanton, J. P., Chapin, F. S., Schuur, E. A. G., & Zimov, S. A. (2008). Methane production and bubble emissions from arctic lakes: Isotopic implications for source pathways and ages. Journal of Geophysical Research: Biogeosciences, 113(3). https://doi.org/10.1029/2007JG000569
  Chanton, J. P., Glaser, P. H., Chasar, L. S., Burdige, D. J., Hines, M. E., Siegel, D. I., et al. (2008). Radiocarbon evidence for the importance of surface vegetation on fermentation and methanogenesis in contrasting types of boreal peatlands. Global Biogeochemical Cycles, 22(4), 1–11. https://doi.org/10.1029/2008GB003274
  Keller, J. K., Weisenhorn, P. B., & Megonigal, J. P. (2009). Humic acids as electron acceptors in wetland decomposition. Soil Biology and Biochemistry, 41(7), 1518–1522. https://doi.org/10.1016/j.soilbio.2009.04.008
  Itoh, M., Ohte, N., Koba, K., Sugimoto, A., & Tani, M. (2008). Analysis of methane production pathways in a riparian wetland of a temperate forest catchment, using δ13C of pore water CH 4 and CO2. Journal of Geophysical Research: Biogeosciences, 113(3), 1–16. https://doi.org/10.1029/2007JG000647
  Verry, E. S., Brooks, K. N., Nichols, D. S., Ferris, D. R. & Sebestyen, S. D. Watershed Hydrology, in Peatland Biogeochemistry and Watershed Hydrology at the Marcell Experimental Forest (eds Kolka, R. K. et al.) 193–212 (CRC Press, Boca Raton, FL, 2011).
  Liang, J., Xia, J., Shi, Z., Jiang, L., Ma, S., Lu, X., et al. (2018). Biotic responses buffer warming-induced soil organic carbon loss in Arctic tundra. Global Change Biology, 24(10), 4946–4959. https://doi.org/doi:10.1111/gcb.14325
  Luo, Y., Ahlström, A., Allison, S. D., Batjes, N. H., Brovkin, V., Carvalhais, N., Chappell, A., Ciais, P., Davidson, E. A., Finzi, A., et al. (2016), Toward more realistic projections of soil carbon dynamics by Earth system models, Global Biogeochem. Cycles, 30, 40– 56, doi:10.1002/2015GB005239.
  Xu, T., White, L., Hui, D., & Luo, Y. (2006). Probabilistic inversion of a terrestrial ecosystem model: Analysis of uncertainty in parameter estimation and model prediction. Global Biogeochemical Cycles, 20(2), 1–15. https://doi.org/10.1029/2005GB002468
  
  Citation: https://doi.org/10.5194/bg-2021-316-AC4

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Reconsider after major revisions (16 Mar 2022) by Akihiko Ito

AR by Shuang Ma on behalf of the Authors (17 Mar 2022) Author's response Manuscript

EF by Sarah Buchmann (18 Mar 2022) Author's tracked changes

ED: Publish as is (28 Mar 2022) by Akihiko Ito

AR by Shuang Ma on behalf of the Authors (28 Mar 2022)

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Short summary

The relative ratio of wetland methane (CH₄) emission pathways determines how much CH₄ is oxidized before leaving the soil. We found an ebullition modeling approach that has a better performance in deep layer pore water CH₄ concentration. We suggest using this approach in land surface models to accurately represent CH₄ emission dynamics and response to climate change. Our results also highlight that both CH₄ flux and belowground concentration data are important to constrain model parameters.