Arctic Inshore Biogeochemical Regime Influenced by Coastal Runoff and Glacial Melting (Case Study for the Templefjord, Spitsbergen)

Round 1

Reviewer 1 Report

Review on  Arctic Inshore Biogeochemical Regime Influenced by Coastal  Runoff and Glacial Melting (Case Study for the Templefjord, Spitsbergen)

 

The paper presents seasonal measurements from Templefjord collected during 5 expeditions in the fjord. The study presents a nice new dataset on biogeochemistry in these understudied fjord. The paper provides some unique seasonal data and in this way merit publication. However, I do have a few issues with some aspects of the paper:

 

Generally, the quality of the figures is poor. Often only limited measurements are available (2 or 3). Connecting these points can give a screwed bias on what real dynamics is and should be avoided. I would strongly suggest or integrate figure A and B, or show the evolution at inner and outer fjord in one figure. Now it is very confusing to scroll between the different figures to understand how the system is changing seasonally and spatially.

 

A good discussion in lacking in my view. There is almost no comparison of the observation to other fjords (e.g. Kongsfjorden) in Svalbard nor to any other fjords (Greenland, Alaska) worldwide impacted by glacial discharge.

 

Minor comments:

 

L58, write out name of authors

 

Material and Methods: It is into specified when chemical measurements are conducted.

E.g. how fast after collection were pH samples analyzed?

 

How confident are you of nutrient (phosphate and silicate) measurement in 3A. To me this seems very much likes an outlier. No other chemical parameter points to the fact that there is glacial activity at depth (e.g. Temperature or salinity).

 

Figure 9: Unclear what the added value is figure 9.

 

L328, I would argue many more factors impact fjord biogeochemistry so I suggest removing this sentence

 

Figure 10: I would not connect sampling campaigns.. many things can happen in weeks between sampling.

 

Spring freshet? I suggest using a different word

Author Response

Thank you for revising! All the answers are in the attached file.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper presents a series of biogeochemical data collected during 5 expeditions from 2011 to 2017, (1-5 marine stations each) in a glaciated fjord in Svalbard, the Templefjord. The valuable dataset spans from February to June and includes water column data as well as data from sediments, ice cores, freshwater streams etc.

The analytical methods and sampling procedures used are generally well described and fully adequate, even if the method section needs an improvement, as reported in the detailed comments.

Figures 8 and 9, are really nice and allow a fast visualization of some results.

However, the paper is basically descriptive and the scientific discussion of the results is poor and does not get advantage of the data from different matrices, as well as it lacks of the more recent findings on fjord’s biogeochemistry as upwelling of nutrients from sediments driven by glacier submarine discharge (Hopwood et al, 2020 for a recent review; Vonnahme et al 2021). The authors have great experience in marine carbon chemistry and polar zones, they could easily improve the paper with some further data analysis to better sustain and improve the discussion. I highlighted some important findings that could better discussed and gave some suggestions to improve this section in the detailed comments.

 

Detailed comments:

FIG 1

Add a line to indicate, approximately, ice extent during winters. Were stations T1, T4, T5 sampled under the ice? I was not able to find st. TM1 on the map. Station TF4 is missing from the captions. Please add also the points or areas were the other samplings (ice cores, sediments etc) were done, use different symbols, the name of the stations does not help a fast identification. Please, add credit for the maps.

L 50-51 Add a link to the two sentences, something as … this is well evidenced in a series o works … or what is more appropriate.

L 58 please, adapt the sentence to the reference style … studies by [24]…

L 65 – 67 Our previous studies … please rephrase to highlight better what is new in this study. It seems that you have already published most of the results, but this is not the case: [27] is a short note with only preliminary results, [19] has only the abstract in English [28] I was not able to find it

L 76 -84 The aim of this paper is ambitious, there is little discussion on processes, none on the rate of transformation.

L 93 ..there is a calving …

L 98 .. please specify that it is basically a water stream, 4-5 km long, draining from Murdochbreen glacier. 

L 105 .. In this study, a total of five expeditions were performed in different seasons in the period from 2011 to 2017

L 108 – 118 A clear description of the ice cover condition of the fjord is missing. Also improve fig 1 with the lines of land fast ice extent during different seasons.

2.2 Methods and data

This section is rather confusing and it is not clearly explained where and when different kind of samples were collected and if seawater was collected under the ice or in free-ice waters. Table A10 helps a little but the position of sediment sampling, ice cores, etc. are not indicated in the map, moreover in the table, samples different than seawater are reported only for June 2017 while in the text other samplings are indicated.

L 123 … what exactly sea ice is? Drifting icebergs? Which dimensions? Which were the sampling protocols?

L 143 Ice cores are not included in table A10, they are not indicated in the map.

L 160 – Were the sample thermostated during pH measurements? At which temperatures? Please add some details on this aspect.

L 180 Have you used Certified Reference Materials or laboratory standards for TIC and Alk measurements? Please add some details on typical precision – accuracy, comparability of the measurements done in different years.

3 Results

L 192-195 Were the station near the glacier ice covered?

L 207 specify that it took place in March. Could it be considered “early spring” or interannual variability?

L 222 – 225 Is this referred to the same station described for the other parameters? If this is the case, avoid repeating that there was a low salinity layer and unify and synthetize the presentation of the results.

L 218 -2019 Move to the discussion

If there is no discussion on the profile of the outer stations, they could be moved to the supporting material and Fig 2 a merged with Fig 3a to allow a better comparison

L 232 – 238 I was not able to identify the data and the trend discussed in the figures. Please clarify.

L 222 -244 the presentation of the results is mixed with the discussion. Please, move all the discussion to the discussion section.

L 248 – 251 In figures 4 and 5 temperatures seems lower than those described in the text.

L 262 ΩAr values in the figures seems lower than indicated in the text

L 265 – 266 move to the discussion

L 277 Caption of fig 6. Please add “near the glacier front”, to help the reader to quickly identify the station position.

L 284 – 289 move to the discussion

L 299 here and throughout the text, use seasonal variability or other expressions instead of "seasonal changes" that refer to a difference between values, not a range of value

3.2 Comparison of nutrients in different Arctic media

Please, move this section to the discussion.

Figure 8. Are “river plume” the values measured at the surface of st. TG1? And “glacier plume” values? How is defined “surface layer”. Please add this information to the caption/text.

It would be really interesting to have similar summary drawings also for TIC, Alk and organic nutrients. Perhaps it is possible to reduce the size of the figure, increasing the font size.

L 313 To asses which is the limiting nutrient is not easy without experiments of nutrient addition. Organisms could also utilize organic phosphorous / nitrogen, etc. Change “testifying” with “suggest” or similar less strong expressions.

L 314 – 325 these are very important observations!

4. Discussion

The discussion is too long and lacks of figures that help to highlight the new results. It mostly compares values from one season or one area to the other. I suggest to explore the data with new figures to evidence the new results and rewrite this section.

Alk and nut /S plots or Alk and nut / freshwater fraction plots compared with freshwater endmembers; T/S plots to synthetize water mass variability. Comparison with Ericson et al., 2019, Fransson 2015, McGovern et al., 2020

Here are some important points that could be better explored:

L 218 -220 the presence of a winter bloom under the ice and its relationship with the wintry subglacial discharge is an important point, with very few observations. Is it possible to better discuss it? It was not mentioned in the discussion section. See the paper of Vonnahme, T. R. et al., 2021.

L 314 – 325 these are important observations. Is it possible to better explore the role of sediments in enriching with nutrients the waters upwelled in the frontal area of tidewater glacier?

L 441 – 444 to compare the data you have to consider the salinity and compare the S / Alk correlations or freshwater fraction / Alk correlation: intercept and slope. Is there a pCO2 /S and / or Omega Ar / S correlation in your data?

References

Several references are incomplete E.G n [9], [28]

[47] I was not able to find the cited reference: the proceedings are available as single pdf files named POAC-11_ nn with no further indications.

References cited in this review:

Ericson et al  Marine CO2system variability in a high arctic tidewater-glacier fjord system, Tempelfjorden, Svalbard 2019  https://doi.org/10.1016/j.csr.2019.04.013

Hopwood, M. J., Carroll, D., Dunse, T., Hodson, A., Holding, J. M., Iriarte, J. L., Ribeiro, S., Achterberg, E. P., Cantoni, C., Carlson, D. F., Chierici, M., Clarke, J. S., Cozzi, S., Fransson, A., Juul-Pedersen, T., Winding, M. H. S., and Meire, L.: Review article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?, The Cryosphere, 14, 1347–1383, https://doi.org/10.5194/tc-14-1347-2020, 2020.

Vonnahme, T. R., Persson, E., Dietrich, U., Hejdukova, E., Dybwad, C., Elster, J., Chierici, M., and Gradinger, R.: Early spring subglacial discharge plumes fuel under-ice primary production at a Svalbard tidewater glacier, The Cryosphere, 15, 2083–2107, https://doi.org/10.5194/tc-15-2083-2021, 2021

Author Response

Thank you for revising! All the answers are in the attached file.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments on “Arctic Inshore Biogeochemical Regime Influenced by Coastal 2 Runoff and Glacial Melting (Case Study for the Templefjord, 3 Spitsbergen)” by Pogojeva et al.

 

Summary

The manuscript by Pogojeva et al. presents an interesting data set which comprises biogeochemical measurements carried out over several years in different environments. The major aim of the study is to investigate the influence of glacial melting and river runoff in the biogeochemical setting of a fjord system in Svalbard. To this end, they use their rather comprehensive data set for depicting the seasonal variability in the fjord, as well as the contrast between its inner (glacier-influenced) and outer areas. I admire the efforts of the authors for putting together this data set and the topic is certainly of crucial relevance in the context of the current uncertainties with regards to the effects of ongoing and future warming in high-latitude ecosystems. In my opinion, however, the manuscript is overly descriptive and the authors fall short in substantiating their conclusions with their data and analysis. I noticed that an appreciable amount of information was shifted to supplementary materials when it could have been easily incorporated into the main document (I found it striking that some of this material is not even referenced at all). Although the authors have a rather unique data set in several environments, their analysis was limited to comparison with literature and description of mean values, which is unfortunate. The lack of deeper analysis results in several rather speculative paragraphs which do not conclusively support the author’s theories as to what are the mechanisms behind the biogeochemical regimes shown by their observations. In this regards I would recommend the authors to analyze N:P ratios rather than describing individual nitrate and phosphate mean values, as well as attempting an estimation of the fluxes between the different compartments (environments) sampled (see also my comment below). This, together with a lack of rigor in the preparation of the document as well as several grammar and syntax mistakes, prevents me from recommending this work for publication in its current state. As mentioned above this data set is relevant and therefore I would hope the editor encourages the authors to consider re-submitting the manuscript.

In the following, I general and specific suggestions which I hope are useful for the authors in case they consider a future submission:

General comments   

Please make sure you undertake a thorough revision of your manuscript to make sure grammar and syntax are appropriate since in its present version, several sections are hard to read. Also, there is an important number of typos which suggest the need of a rigorous proofreading is needed. Moreover, the authors should make sure they use appropriate terminology for describing standard concepts. Just as an example, saying that you sampled in several “media” is less appropriate as saying that you sampled in several environments, as the authors did. Other example is the usage of “testify”. I believe the authors rather mean “evidence” or similar.

I recommend the authors checking for consistency when using abbreviations and chemical names. These should be spelled in full upon first usage and then written uniformly throughout the paper.

Most of the document is very descriptive. Seeing means and standard deviations from so many parameters makes it hard for the reader to grasp the message you are trying to convey.

Abstract: although the thematic of the study is clear, this section fails to show the novelty of the study beyond general concepts which are known already. Again, this is a great data set, but the authors have to make a better job in showing what we learn from their data; i.e. which data/understanding gap you are filling with your study?

In several parts of the manuscript the authors refer to a phytoplankton bloom, and yet, no quantitative evidence of this is shown. With such a comprehensive data set I find it hard to believe that there are no data to target this since it is part of the crux of the study.  

References: I recommend the authors to make sure they check them all and correct misspellings.

Specific comments   

l.25-26: the authors mention that their results may serve as a basis to “extrapolate” to other Arctic regions. However, I fail to see how they did that and this is not discussed at all in the paper.

l.57-58: the authors mention the importance of the inflow of Atlantic waters in the Arctic. However, the references they use are not appropriate for discussing the physical context of this process (“Atlantification”). Seminal papers such as, for instance, Polyakov et al. 2017 (see https://www.science.org/doi/10.1126/science.aai8204) would be more appropriate.

l.70-74: a reduced version of this paragraph could help strengthening the abstract in terms of clearly indicating the relevance and novelty of the study.

l.119-188: “Methods and data”. In this section the authors jump back and forth between explaining the sample and measurement procedure for each parameter, which makes it confusing. It would be better to provide the full explanation for each type of parameters instead. Also, there is repetitive information which should be deleted. Furthermore, it is confusing that the authors cite standard methods from a publication and then go ahead and explain them. Unless there are modifications with respect to such standard methods, these do not have to be explained in detail. This saves some space.

l.145-147: the authors write that ice cores were melt under “light conditions”. This seems puzzling to me since light is exactly what one tries to avoid when handling environmental samples subject to biological activity (except perhaps for targeted incubation experiments, which is not the case here).

l.284-289: here the authors discuss their nutrient values with respect to “background values”. However, it is not clear at all which are those values or how they were obtained. This paragraph is also an example of one of those in which unsubstantiated theories are presented as if they were solid results, despite the lack of quantitative evidence.

l.298: the authors mention in loosely in the introduction that permafrost was sampled. Afterwards there is no mention of this in the methods, and yet the term appears in the results as if data was presented. Based on what appears in the paper one can only see the nutrient values in Figure 8. The authors should make sure they present the methods in a clearer and structured way since otherwise it is very hard to follow what was done where.

l.301-304: “Figure 8”. This is a good attempt to display schematically all environments in which the authors sampled. However, more than just concentration values, it would be much more informative to see budgets and fluxes among the different components of the fjord system. I sincerely hope that authors consider carrying out such an analysis for a future submission. This would be an important contribution to help better constraining biogeochemical models.

l.305-307: “Figure 9”. I do not consider this figure to be informative and strongly suggest the authors to omit it to leave place for other (more relevant) plots.

Figures: I respectfully suggest the authors to consider showing summary plots (e.g. with several pannels) that include all stations during the seasonal and the inshore-offshore comparison. This would prevent the reader from having to go back and forth between the main text and the supplementary to be able to understand the manuscript. Beyond this aspect, and in my opinion more importantly, is the fact that information needed for understanding the manuscript was send to the supplementary, which is generally not a good practice.

    

Author Response

Thank you for revising! All the answers are in the attached file.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have significantly improved the manuscript and now the work done is clearly explained with improved discussion. There are some typo in the text.

L 116 Fig 1 caption. Please add: The dotted lines indicate the winter positions of the solid ice boundaries in 2017 and 2011.

L 220 Fig 2 caption. Delete the repetition of “ at the station” at the end of the caption

Fig 5, 6 etc: there is a “DOC X ax” with no DOC data

Author Response

Dear reviewer, thank you very much for your work and for appreciation of our work!

We've addressed your correction in the manuscript text listed below:

L 116 Fig 1 caption. Please add: The dotted lines indicate the winter positions of the solid ice boundaries in 2017 and 2011.

Thank you. Caption added.

L 220 Fig 2 caption. Delete the repetition of “ at the station” at the end of the caption

Deleted

Fig 5, 6 etc: there is a “DOC X ax” with no DOC data

DOC X ax removed from the picture

Reviewer 3 Report

I revised an earlier version of this manuscript and expressed my concerns with respect to form and format, despite the high relevance of the topic. I appreciate the efforts of the authors in addressing my and other reviewer's comments, and yet, still think the experimental design could have been better designed. However, in the new version the authors do acknowledge the limitations of their study. It is my opinion that the authors made the best possible use of their data and it is important for the community that these results are made available. I noticed that in the supplementary there are plots with non-english characters and in quite a few of the numbers the decimals are separated with commas and not points. This may be a technical detail, but it needs to be corrected before final publication.    

Author Response

Dear reviewer, thank you for appreciation of our work!

We've made changes in the figure in Supplementary according to your comments, commas changed to points. Thank you!