Blue Nitrogen: A Nature-Based Solution in the Blue Economy as a Tool to Manage Terrestrial Nutrient Neutrality
Round 1
Reviewer 1 Report
I have not previously seen a Policy Briefing in Sustainability journal, but given the previous admissibility of a Guest Editor, I will skip that.
This theoretical article is interesting, but needs to strengthen its ideas, especially its role with the blue economy and sustainability, in terms of the SDGs.
1) Blue economy is part of the title, key words, but theoretically little discussed. I would like to recommend this article as a starting point to search for references and deepening on the blue economy and its epistemology: https://doi.org/10.3390/w13223234.
2) Regarding Sustainability, it has strongly permeated the field of research (see: https://doi.org/10.1371/journal.pone.0265409), in its case the text approaches SDGs 14 and 15, but there is no in-depth discussion of environmental SDGs (see: https://doi.org/10.1109/COMST.2018.2812301).
3) Even though this is a theoretical article, it is possible to provide an analysis methodology.
4) Establishing a theoretical discussion in contrast to other similar contemporary articles is something that should be incorporated in order to highlight the importance of the study.
5) It is necessary to take attention to the format (e.g. a table 1 is mentioned, which is not presented), the references are not presented in the journal style and do not state the DOI's available.
Author Response
This theoretical article is interesting, but needs to strengthen its ideas, especially its role with the blue economy and sustainability, in terms of the SDGs.
1) Blue economy is part of the title, key words, but theoretically little discussed. I would like to recommend this article as a starting point to search for references and deepening on the blue economy and its epistemology: https://doi.org/10.3390/w13223234
As the reviewer mentions the theoretical background to the BE has been well documented and much discussed. Such a discussion we feel is beyond the scope of this paper, but we have included text and references that acknowledge this previous work and demonstrates where this current work sits within the on-going dialogue
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2) Regarding Sustainability, it has strongly permeated the field of research (see: https://doi.org/10.1371/journal.pone.0265409), in its case the text approaches SDGs 14 and 15, but there is no in-depth discussion of environmental SDGs (see: https://doi.org/10.1109/COMST.2018.2812301).
Again this is beyond the scope of this report but we have made a specific link to the SDGs within the text, we have chosen to concentrate on metrics that are of direct interest within the policy framework we have developed.
3) Even though this is a theoretical article, it is possible to provide an analysis methodology.
As a policy brief type article, an analysis methodology is not appropriate, but there is a section that describes the approach we have taken.
4) Establishing a theoretical discussion in contrast to other similar contemporary articles is something that should be incorporated in order to highlight the importance of the study.
In the introduction we place the concept being discussed within the current theoretical and regulatory frameworks, and later also discuss the value of this approach, we are reluctant to add an additional section to the article.
5) It is necessary to take attention to the format (e.g. a table 1 is mentioned, which is not presented), the references are not presented in the journal style and do not state the DOI's available.
The references have been reformatted to the appropriate style and the reference to table 1 has been removed.
Reviewer 2 Report
The topic of nitrogen management in marine systems is a complicated issue involved with multiple stack holders. This manuscript not only outlines the current challenges but also proposed a new perspective based on the marine environment instead of the terrestrial one. New concepts and actions proposed in this manuscript carry great importance to the health of marine in the future.
One minor revision: There are some minor reference format issues. Please check.
Author Response
The referencing issues have been resolved
Reviewer 3 Report
The topic of Blue Economy is novel and necessary for various stakeholders, including businessmen, politicians, scientists, and society in general. Though I see the potential for this article to be published, there are a lot of things to be improved.
To begin with, I am not sure whether the paper is relevant to the type of publications: "Articles". This type of publication should be original research manuscripts with scientifically sound experiments. It is mean that the structure of the paper includes the following sections: Introduction; Materials and Methods; Results; Discussion; Conclusions.
The goal of the paper is not presented. Usually, it should appear in the introduction but here the authors do not indicate the aim at the end of the paragraph. The introduction should briefly place the study in a broad context and highlight why it is important. It should define the purpose of the work and its significance, including specific hypotheses being tested. Please highlight controversial and diverging hypotheses when necessary. Keep the introduction comprehensible to scientists working outside the topic of the paper
The methodology part should be added.
Finally, I can only see the conclusions, the “Discussion” part is missing. It lacks a deeper analysis behind the facts given and the comparison with other research studies. I believe this is related to the issue of the insufficient literature review of the particular topic.
Author Response
The topic of Blue Economy is novel and necessary for various stakeholders, including businessmen, politicians, scientists, and society in general. Though I see the potential for this article to be published, there are a lot of things to be improved.
To begin with, I am not sure whether the paper is relevant to the type of publications: "Articles". This type of publication should be original research manuscripts with scientifically sound experiments. It is mean that the structure of the paper includes the following sections: Introduction; Materials and Methods; Results; Discussion; Conclusions.
The reviewer is correct and I apologize for any confusion. It was originally designed as a policy brief. As the journal does not support this article type it has been re-formatted to a perspective piece and therefore does not follow the Introduction; Materials and Methods; Results; Discussion; Conclusions format of an Article.
The goal of the paper is not presented. Usually, it should appear in the introduction but here the authors do not indicate the aim at the end of the paragraph.
This has now been added to the introduction
The introduction should briefly place the study in a broad context and highlight why it is important. It should define the purpose of the work and its significance, including specific hypotheses being tested. Please highlight controversial and diverging hypotheses when necessary. Keep the introduction comprehensible to scientists working outside the topic of the paper
The introduction has been modified to follow this advice, however as we are not putting forward a hypothesis so have not included this within the introduction
The methodology part should be added.
A short section on the methodology has been added but as it is a perspective this is not in the same format as for an Article.
Finally, I can only see the conclusions, the “Discussion” part is missing. It lacks a deeper analysis behind the facts given and the comparison with other research studies. I believe this is related to the issue of the insufficient literature review of the particular topic.
A perspective piece does not have the space for a longer discussion, and this paper only lays out the framework for the Blue Nitrogen concept, and does not attempt a deeper analysis which might be more appropriate in a review paper.
Author Response File: 
Author Response.docx
Round 2
Reviewer 1 Report
Proposing a manuscript whose title refers to the blue economy, sending it to a special issue on blue economy, to say that the blue economy escapes from the manuscript... It does not make sense.
If an article is not raised in discussion with other classical and contemporary references, there is no way to evaluate its scientific contribution.
Author Response
We have now included a short section on the context of the Blue Economy, but it is specifically because this is an issue on the BE that we feel that there is not space for further discussion on the development of the BE as a framework.
Reviewer 3 Report
I have rechecked the requirements for the article type "Perspective ". The structure should include an Abstract, Keywords, Introduction, Relevant Sections, Discussion, Conclusions, and Future Directions.
This paper does not include Discussions and Future Directions.But as I had indicated before, the title of the paper was interesting, and I saw an opportunity for publishing
Author Response
The article has been proofread again and now includes the sections 'Discussion and Policy Recommendations for valuing Blue Nitrogen' and a 'Conclusions and Future Directions'
Round 3
Reviewer 1 Report
It is recognized that, at least, an alignment was achieved between the special issue, the article title and its content.
Author Response
I thank the reviewer for their work
Reviewer 3 Report
The paper is ready for publication
