Review of the Influence of Climate Change on the Hydrologic Cycling and Gaseous Fluxes of Mercury in Boreal Peatlands: Implications for Restoration

Round 1

Reviewer 1 Report

General

1)      from Water website: The type of publication

"Review:

Reviews offer a comprehensive analysis of the existing literature within a field of study, identifying current gaps or problems. They should be critical and constructive and provide recommendations for future research. No new, unpublished data should be presented. The structure can include an Abstract, Keywords, Introduction, Relevant Sections, Discussion, Conclusions, and Future Directions, with a suggested minimum word count of 4000 words."

perhaps this is more appropriate?

"Communication

Communications are short articles that present groundbreaking preliminary results or significant findings that are part of a larger study over multiple years. They can also include cutting-edge methods or experiments, and the development of new technology or materials. The structure is similar to an article and there is a suggested minimum word count of 2000 words."

2)      Following on #1 above – there is great value to the compilation of information in this manuscript but I think the organization and presentation of the information needs better context.  The presentation as a literature review comes through as thin whereas focusing the presentation on the unique nature of this collection of studies and providing the context as a comparison or validation of the innumerable lab-based and isolated small-scale studies that have to date fed the current Hg cycling reviews would be most powerful. I’ve tried to highlight where the changes seem most impactful in the text edits below. Lean into the need for more comprehensive/wholistic studies like this to actually validate the current conceptual models.

3)      I think a figure showing a conceptual model and where the main take homes reside within that model would help guide the reader better and further reinforce the value of these types of studies relative to isolated lab/small scale field studies.

4)      There are many typos and small grammatical errors throughout the document – strongly recommend using spelling and grammar check features in the program used to prepare the text.

Title:

specify 'boreal' in the title to represent proper scope/context for the article.

Abstract:

Line 12: I struggle with the use of the term “preliminary data” in a review. It also seems to me that the value of the information collated in this manuscript is the focus on large-scale monitoring and/or manipulative experiments which fits the “communication” format better than a ‘review’, especially in the context of “preliminary” data included (published but part of an unfinished study).

Lines 17-22: consider simplifying these sentences. The text is hard to follow.

Line 29: what is meant by “MeHg availability”? available for hydrologic transport?

Line 31: …Hg (and S compounds).  – should it be Hg (and S) compounds? I think this refers to Hg compounds (MeHg, THg, others?) and S compounds rather than “mercury” and “S compounds”

Line 32: what is meant by “Hg products” – species? Or “compounds” as above?... generally, be consistent in terminology.

Suggest reworking the abstract after other edits are made.

Introduction:

Lines 66-69: The tone of this statement is that there is little information to work with and you are just synthesizing that small contribution, when in fact there are innumerable studies that have investigated Hg cycling and the factors affecting methylation rates, etc… and here you are providing an unique perspective of data compiled from a collection of rare, ecosystem-scale efforts that can validate or illuminate our current understanding of how these factors interact via synergistic and competitive relationships. This speaks directly to the intent of the “Communications” article format of presenting “significant findings that are part of a larger study over multiple years… include cutting-edge methods or experiments“… I encourage you to engage the readers from this perspective and perhaps inspire funding agencies to recognize the value of these large-scale efforts.

Line 75: the focus should hit hard on the context of these studies relative to the typical studies that make up the vast majority of the literature.

Lines 78-86: this seems out of place and too negative in tone, focused on what is not there versus what is. I recommend moving this info ahead of the “Focus” statement that precedes it and again foreshadow how these large-scale studies help fill the gap.

Review of Literature

Suggest renaming this section. Maybe “Large-scale efforts in boreal wetlands” or “Data sources” or something else that is analogous with the “site” or “methods” of a typical article.  This is what this section seems to be when read. Instead of the tone being ”I reviewed these…” take the more active “I evaluated data from five large-scale research programs, highlight that these are not all completed and some data collections are ongoing.

Line 106: do not dwell on what this does not do, focus on what it does. This manuscript does not thoroughly consider any of the mechanisms but rather presents the large-scale study perspective and value of this approach.

Table – please add some info about the types of data contributing to the evaluation for each study to provide context on intersection/union of study findings. Perhaps pair this with a conceptual model figure? would be nice to have a better sense of the type of Hg-MeHg data evaluated - soil/peat, surface water, pore waters... and some sense of the ancillary measurements to provide context for corroboration vs leveraging to reach conclusions. Also might be nice to have a column with the pertinent references by study (would also highlight the value of these large efforts)

Climate Change effects…

This seems like the “results/discussion” section of an article and the mechanisms are not exclusively climate change driven. Reorganized to interact with a conceptual model, this section could be more impactful.

Section 3.4 touches on a nice compare/contrast of restoration vs climate change effects. Could further explore these overlapping effects, not to mention the Q about whether restoration is even feasible in certain cases where the production/decomp balance has been so altered by climate change or whether there are opportunities to restore wetlands to be more resilient to climate change.

Wetland restoration

 This section seems a bit isolated and disjointed from the previous section. Suggest integrating sections into previous text where appropriate.

Lines 227-246: this seems like it belongs in the introduction?

Lines 246-261: this seems to dovetail nicely into the previous section within the discussion of fluctuating water levels – lends itself to the compare/contrast restoration and climate change effects

Conclusions

I think the conclusions would benefit from first noting the value of these large-scale studies in validating/illuminating what previous isolated studies have suggested via the conceptual model – lines 274 – 277 make a good base for this.

Suggest reworking the conclusion statements after other edits are made.

Proficient English but there are many typos and minor grammatical errors/repeated words. noted in review.

Author Response

Please see attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper by Kolka represents a good, comprehensive, interesting, and valuable review of the influence of Climate Change on the Hydrologic Cycling of Mercury in Peatlands. The paper explores into the impacts of climate change on the cycling of mercury in peatlands and provides insights into the potential implications for restoration efforts.

The review is well-organized and clearly structured, with sections devoted to different aspects of the topic and offers a comprehensive understanding of the subject matter.

Overall, "Influence of Climate Change on the Hydrologic Cycling of Mercury in Peatlands: Implications for Restoration" offers a valuable contribution to the literature on peatland ecology and environmental management. By elucidating the intricate connections between climate change, hydrology, and mercury dynamics, the review enhances our understanding of these complex systems and provides important insights for conservation and restoration efforts in peatland ecosystems.

Author Response

Please see the attachment

Author Response File: Author Response.pdf