The Characteristics of Gas and Particulate Emissions from Smouldering Combustion in the Pinus pumila Forest of Huzhong National Nature Reserve of the Daxing’an Mountains
Round 1
Reviewer 1 Report
Manuscript Number; forest-2128537
Title; The characteristics on gas and particulate emissions of smouldering combustion in the Pinus pumila forest of Huzhong National Nature Reserve of the Daxing’an Mountains
Although the topic is of interest to the Scientific community, before consideration for publication, this paper should be improved. Authors should reconsider the main objective of the paper according to the content. They should try to synthesize and emphasize the main findings of the study and avoid long sentences. Furthermore, authors should avoid drawing risky conclusions.
Evaluation; Major Revision.
1. Abstract need to revise.
e.g. - CO2 and CO, and the particulate emissions >>> should be “CO2 and
CO, and particulate matter (PM).
- Do not put any equation in the abstract.
2. Method;
- What is hm2 ?
- 2.39%, 11.81%, 22.43%, and all of the main text, many numeric data are given with too many significant figures; 2 significant figures suffice, and 3 suffice in case the first significant figure is "1".
- PM2.5,PM4, PM10, Why the author did measure this particle size?
Generally, PM2.5 is fine particles and PM10 is coarse particles. What is important to study PM4?
3. Why did the author measure the emission factor? Please explain the important work and put the significance in the introduction part.
4. In this study, the author focuses on carbon emissions from forest fires. How many percentages of each species of carbon? By evaluation of Emission Factor.
5. Discussion should be more detailed based on certain results or comparisons with other authors’ results.
6. Conclusion; Many paragraphs are too short. Please revise and combine them into only one paragraph in the conclusion. The conclusions could be further developed, there is a lot of interesting data in the article.
Comments for author File: 
Comments.docx
Author Response
Response to Reviewer 1 Comments
Dear reviewer,
Thank you very much for the advice, which is very important for the improvement of our paper. We have carefully revised the paper and the details are as follows.
Point 1: Abstract need to revise.
Response1: We have revised the abstract.
Point 2: Method
Point 2.1: What is hm2
Response 2.1: hm2 is the unit of “hectare” that commonly used in China, we have changed “hm2” to “ha” in the manuscript.
Point 2.2: 2.39%, 11.81%, 22.43%, and all of the main text, many numeric data are given with too many significant figures; 2 significant figures suffice, and 3 suffice in case the first significant figure is "1".
Response 2.2:We have revised the significant figures of MC in the paper.
Point 2.3: PM2.5, PM4, PM10, Why the author did measure this particle size? Generally, PM2.5 is fine particles and PM10 is coarse particles. What is important to study PM4?
Response 2.3: At present, there are few studies on the emission of different levels of PM from forest smoldering, and the conclusions are not consistent. By the detection of PM at different level, we aimed to found the relationship between PM emission characteristics and particle sizes. Results showed that the combustion time for the peak concentration of PM2.5 lagged behind that of PM4 and PM10 and the hysteresis was more obvious at higher moisture content.
Point 3: Why did the author measure the emission factor? Please explain the important work and put the significance in the introduction part.
Response 3: We have revised the introduction and explained the study of EF in line 128~130.
Point 4: In this study, the author focuses on carbon emissions from forest fires. How many percentages of each species of carbon? By evaluation of Emission Factor.
Response 4: According to the references, CH4 and other organic gas would also emit from the forest smoldering. CH4 was detected occasionally in our experiment also, but the emission of CH4 was too low to be detected continuously, so we didn’t research the emission of CH4 in the paper. Because of this, we couldn’t give the percentages of CO2 and CO in the carbon emission.
Point 5: Discussion should be more detailed based on certain results or comparisons with other authors’ results.
Response 5: We have revised the discussion part.
Point 6: Conclusion; Many paragraphs are too short. Please revise and combine them to only one paragraph in the conclusion. The conclusions could be further developed, there is a lot of interesting data in the article.
Response 6: We have revised the conclustion part and some new foundings were added in the discussion part.
Author Response File: Author Response.doc
Reviewer 2 Report
Dear authors!
Your research is relevant to Forests journal, but manuscript has some disadvantages at present time.
Title:
I think more suitable title is: The characteristics of gas and particulate emissions from smouldering combustion in the Pinus pumila forest of Huzhong National Nature Reserve of the Daxing’an Mountains
Abstract
Please, remove logarithmic expressions from the abstract. More suitable to write, that experimental expressions were obtained for collected data.
Introduction
I think your Introduction must be completely reworked. You must provide full picture of gas and PM emissions in global scale taking into account regional aspects of your study area. I found only 14 cited reference in Introduction. This is totally unacceptable situation. I estimated the quantity of relevant international works about 50-60 original references. Moreover, there is official documents on emission factors, for example, in the USA.
Methods
Please provide map of sudy area in this section.
Please, provide full description of experimental installation taking into account scheme of this installation.
Please provide full description of uncertainty analysis procedure in this section. How many experiments were conducted for each point on the plotted graphs?
Please, provide photo of forest fuel samples in this section.
PLease, provide description of particulate monitor MetOne 831.
Results
Why did you consider only CO2 and CO gas emissions. I think is more properly for such study to take into account CH4 emission too. Please, give the support for your decision taking into account references.
Figure 1.a - I did not find confidential inrevals for plotted points in this picture. Please, provide such information for this picture.
Figure 1.c - Please, explain relatively huge confidential intervals for time points on 1.5 and 3.5
Table 2 - Please, explain differences in confidential intervals for PM10 for different moisture content. Look at the table and explain 10 times increasing of confidential intreval for MC=11.81 comparatively to MC=2.39
Why did you choose MC at the levels 2.39, 11.81 and 22.43 %?
Figure 3 - I think that dependences on figures a,b, and c must be the same, namely, cubic parabola like picture a, b. Linear fit for picture c is errorous and do not reflect real disctibution of data.
Discussion
Please, take into account comments in Results section to rework Discussion section.
Conclusion
Please, provide limitations of your research and describe further researches.
References
Please, extend this list of cited works. I estimate this quantity about 70 original items.
Author Response
Response to Reviewer 2 Comments
Dear reviewer,
Thank you very much for your advice, which is valuable and very helpful for our paper. We have carefully revised the paper and the details are as follows. Should you have any questions, please contact us without hesitate.
Title
Point 1: I think more suitable title is: The characteristics of gas and particulate emissions from smouldering combustion in the Pinus pumila forest of Huzhong National Nature Reserve of the Daxing’an Mountains
Response 1: We have revised the title.
Abstract
Point 2: Please, remove logarithmic expressions from the abstract. More suitable to write, that experimental expressions were obtained for collected data.
Response 2: We have removed the equations in the “Abstract”.
Introduction
Point 3: I think your Introduction must be completely reworked. You must provide full picture of gas and PM emissions in global scale taking into account regional aspects of your study area. I found only 14 cited reference in Introduction. This is totally unacceptable situation. I estimated the quantity of relevant international works about 50-60 original references. Moreover, there is official documents on emission factors, for example, in the USA.
Response 3: We have revised the inroduction ( Main part in line 92~105).
Methods
Point 4: Please provide map of study area in this section.
Response 4: The map of the study area is shown as Figure 1.
Point 5: Please, provide full description of experimental installation taking into account scheme of this installation.
Response 5: In order to fully display the installation, the schematic diagram of experimental installation is shown as Figure 3.
Point 6: Please provide full description of uncertainty analysis procedure in this section. How many experiments were conducted for each point on the plotted graphs?
Response 6: We have added the description in line 186~188.
Point 7: Please, provide photo of forest fuel samples in this section.
Response 7: We have added the photo in Figure 2.
Point 8: Provide description of particulate monitor MetOne 831.
Response 8: We have added the description in line 205~207.
Results
Point 9: Why did you consider only CO2 and CO gas emissions. I think is more properly for such study to take into account CH4 emission too. Please, give the support for your decision taking into account references.
Response 9: CH4 was detected occasionally in our experiment actual, but the emission of CH4 was too low to be detected continuously, so we didn’t research the emission of CH4 in the paper. Because of this, we couldn’t give the percentages of CO2 and CO in the carbon emission.
Point 10: Figure 1.a - I did not find confidential intervals for plotted points in this picture. Please, provide such information for this picture.
Response 10: We have redrawn this part, and shown as “Figure 4.a”.
Point 11: Figure 1.c - Please, explain relatively huge confidential intervals for time points on 1.5 and 3.5
Response 11: In this paper, the soil in situ of the study area was used as the experimental sample. Although the sample had been pretreated, the homogeneity was poor compared with that of the commercial soil. Therefore, the SD of smouldering combustion is larger. In addition, the combustion temperature varied greatly around 1.5 h and 3.5 h, this could also increase the fluctuation in gas emissions.
Point 12: Table 2-Please, explain differences in confidential intervals for PM10 for different moisture content. Look at the table and explain 10 times increasing of confidential interval for MC=11.81 comparatively to MC=2.39
Response 12: In addition to the sample homogeneity, the PM emisstions variation at 11.81% MC were more complex as we mentiond in line 485~490.
Point 13: Why did you choose MC at the levels 2.39, 11.81 and 22.43 %?
Response 13: According to the field measurement, the most common MC of the different samples were about 2%, 12% and 22%(Line 183~187).
Point 14: Figure 3 - I think that dependences on figures a, b, and c must be the same, namely, cubic parabola like picture a, b. Linear fit for picture c is errors and do not reflect real description of data.
Response 14: We highly agree with your opinion, and we also point that the equation 5 shown in figure c can’t explain the observed values with drastic change. The low R2 value also confirmed the low fitness (Line 337~345).
Discussion
Point 15: Please, take into account comments in Results section to rework Discussion section.
Response 15: We have revised this part.
Conclustion
Point 16: Please, take into account comments in Results section to rework Discussion section.
Response 16: We have revised this part.
Reference
Point 17:Please, extend this list of cited works. I estimate this quantity about 70 original items.
Response 17: We have referred to more relevant research and extended the cited studies.
Author Response File: Author Response.doc
Round 2
Reviewer 1 Report
This revised version is suitable for publication.
Author Response
Dear reviewer,
Thanks for your approval, and we will keep trying in the follow-up study.
Reviewer 2 Report
Dear authors!
Thank you for your revision.
Manuscript was improved but I suggest some more improvements again.
Introduction
You should extend background information taking into account additianal number of relevant works on gas and aerosol emission. I estimate total number of cited works in Introduction about 50-60 cited works. I found only 33 references. This number is too small for background part of the research article.
Methods
Please, clarify how confidential interwals calculated? What distribution was used? For example, some scientist use normal distribution and Student coefficient with corresponding confidential probability to calculate confidential intervals. Please, clarify uncertainty analysis more precise.
Results
Fig. 6.c - My suggestion to reconstruct fiiting curve did not take into account. I suggest to use cubic fitting again.
Discussion
Please, correct this section according suggested changes in Results section.
References
Please, extend this list. I estimate total number of references abou 70 cited works.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
