Characteristics of Pyrolysis Products of California Chaparral and Their Potential Effect on Wildland Fires

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The work Characteristics of Pyrolysis Products of California Chaparral  and Their Potential Effect on Wildland Fires is interesting. However, after my careful review the work needs to be improved. Specific comments are as following.

 

The language and presentation quality needs to be improved.

Please highlight the novelty of work

ceramic glass windows was utilized to maintain an oxygen-free, high temperature environment essential for pyrolysis of samples. However, in Fig. It is shown that air is used as media as well. Which contains oxygen. Please justify by maintaining the oxygen free zone in that particular case for pyrolysis.

Tar extraction and yield could be in same heading. Tar yield eq. Needs to be presented. In addition, generally tar is removed via absorption in tower and then passed through the cooling media for yield. But its confusing here. Please clarify.

Please place description of analytical techniques in same heading i.e. GC MS and others and brief description would be enough.

TGA and ultimate analysis are very essential for materials used for pyrolysis and it seems missing. Please include that as well.

How HHV of various samples was determined. Please include in analytical section.

Please present statistical analysis results (ANOVA) in the results section and describe accordingly.  

Conclusion needs to be revised.

Comments on the Quality of English Language

The language and presentation quality needs to be improved.

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

Review of “Characteristics of Pyrolysis Products of California Chaparral and Their Potential Effect on Wildland Fires” by Alizadeh et al.

 

Abstract: The abstract clearly states the aim of the study, which is to investigate the pyrolysis of selected foliage species and estimate the energy content of the volatiles released. It also highlights the relevance of this research to understanding wildland fires. It provides extensive experimental about the experimental setup, and the details about the plant type adds regional context. The identification of major product components is noted along with the heating values, which is valuable for evaluating the potential energy contribution of these volatiles during fires. This quantification is the key contribution of the work. Suggestions for improvement: 

(1)while the abstract touches on the importance of understanding pyrolysis, a brief mention of existing research status or knowledge gaps could better frame the work’s significance.  

(2) In light of the 200 word abstract limit, the cost of the experimental detail is that few results have been included here – with more conciseness in the experimental detail, more results could be included here.

(3) Briefly describing how these results contribute to broader scientific or practical applications in fire ecology or management would add impact to the abstract.

(4) The sentence L16-18 is very general and seems out of place after experimental detail has been presented. It could either be an abstract’s introductory statement or begin a concluding remark.

Introduction: The literature review contains many relevant citations. It would benefit from a clear statement of the paper’s objective early on.

The transition between different sections and ideas could be smoother. Also, please check that each paragraph logically follows the previous one, building a coherent story.

There seems to be some redundancy, such as mention of impact of temperature and heating rates on pyrolysis several times.

Key technical terms like pyrolysis and thermal degradation should be briefly explained.

 

Materials and Methods:

Thorough, but organize components into a few groups, as these fall into equipment, techniques, products, and species studied.

 

Results: The results section provides detailed data and analysis of pyrolysis products from various species. Please improve for clarity and readability. For example,

(1)   The section is very dense and lengthy, making it hard to follow. An introductory paragraph indicating what will follow and then breaking Results into subsections could enhance readability.

(2)   Some sentences could be simplified, for example- L240-249.

(3)   Please define abbreviations such as “daf” at first mention.

(4)   Table 2 needs clearer headings and units. It’s not immediately clear what “Tar”, “Gas”, and “Char” percentages refer to.

(5)   The reference to Table 3 should indicate what it shows without the reader having to figure it out.

(6)   It would be helpful to highlight key similarities and differences more explicitly.

(7)   Only results, not reflection on them or comparison with other studies, go in this section. L408 – This paragraph has components that are out of place. The initial line referring to the paper’s focus is out of place, deep in the results. L414-418, the comparison with previous studies, belongs in the Discussion. Similarly, L432-437 are comparisons with other studies.

 

Conclusions: The conclusions of the study on characteristics of pyrolysis products from several southern California plant species are very detailed and provide insights that will contribute to combustion research. The comparison to results from plant species in the southern U.S. contributes to a better understanding of regional similarities and differences. The detailed chemical analysis will be useful for applications and management. Suggestions for improvement:

(1)   The study focuses on a relatively small number of plant species for detailed analysis, but this limits the generalizability of the findings. Any comments on generalizability of the narrow findings? suggestions for future research?

(2)   The conclusion could benefit from some discussion how these compare with other studies beyond the U.S., in the context of global biomass pyrolysis research.

(3)   Can anything more be said about the secondary pyrolysis reactions and their implications for the composition and energy content of products?

 

 

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

This is one of the most well-written drafts I have reviewed, my congratulations to the authors for their careful work! Well done! Honestly, you've made the review process a breeze with this paper. 

Here are the points I appreciate:

- The paper is clearly written and follows a straightforward train of thought. 

- The grammar is exceptional. 

- The study is tied in well with current wildfire concerns, including emissions. The focus on California species is also apt considering the recent growth in attention given to California's changing climate, this past couple years' wetter winters and the increase in fuel. 

- The study provides all necessary background information, including a solid foundation in previous studies. It is well cited. 

I have one moderate suggestion and a few minor suggestions, but otherwise, great work!

My moderate suggestion is in response to line 490, referring to the study's ability to provide helpful data for fire simulation models. This would only be true for physics-based fire models, and likely only those focused on fire emissions. The fire simulation models most widely used in the US are more simplified (though this is not to say that they are simple...) and the detail of your study would be lost on them. These more commonly used models are great for forecasting metrics such as PM2.5 concentration, and aerosol optical depth. So I would caution the use of this claim without a statement that ties this work to those models, or a specific physics-based fire model that would make use of these detailed results. If clarification on the different types of fire models is needed, I would recommend looking at the set of three papers published in 2009 by Sullivan. It is a review of the fire models developed at the time, and may be informative. 

Below are my minor suggestions:

line 39 I would like to see a citation for the sentence ending here. 

line 46 indicates a 'couple' differences, but there are more than two differences, so, perhaps change the word 'couple' to 'few'. 

line 125 'at the beginning and end of the day' could be more specific. Are the collections 12 hours apart?

The text and diagram in Figure 3 are elongated and could be resized to be proportionate. 

There is a white highlight to the text in lines 293-296. 

 

Otherwise, again, well done on this manuscript draft!

 

 

 

Author Response

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Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The revised manuscript is significantly improved over the original.  The authors have responded to each of my comments.

My one remaining concern is “Section 3. Results and Discussion”. The authors responded to my original concern about the section “Results” containing more than only presentation of results but also comparison to other studies and some introspection about the context of the study (L456-458) by renaming Results to "Results and Discussion”. I reiterate that it is important that there be a Results section that only contains Results, and Discussion about the results including the comparisons to other works and reflections on context be moved to a Discussion section.

Author Response

Comment: 

The revised manuscript is significantly improved over the original.  The authors have responded to each of my comments.

My one remaining concern is “Section 3. Results and Discussion”. The authors responded to my original concern about the section “Results” containing more than only presentation of results but also comparison to other studies and some introspection about the context of the study (L456-458) by renaming Results to "Results and Discussion”. I reiterate that it is important that there be a Results section that only contains Results, and Discussion about the results including the comparisons to other works and reflections on context be moved to a Discussion section.

Response:

We appreciate the previous comments of this reviewer. However, we disagree with this particular comment. The reviewer wants us to follow a classical style that presents a result and then have a separate discussion. We have many varied results on different aspects such as yield, speciation, and heating value. We have therefore presented a "just-in-time" discussion of each result, and made one "Results and Discussion" section. Other reviewers have commented on how easy this paper was to follow. We have addressed all of the technical concerns from all of the reviewers. We strongly feel that breaking this particular section into two parts (i.e., a Results and then a Discussion) would severely hamper the flow of the paper, making the reader dart back and forth between sections. We therefor appeal to the editor to permit the publication of this paper in its current form.