Structure–Biodegradability Relationship of Nonylphenol Isomers in Two Soils with Long-Term Reclaimed Water Irrigation

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Reviewer #1:

1. There is no sampling procedure, depth, or random selection of the soils evaluated.

Response(R): Accepted and revised in L95-105. Five-point sampling method was used in both fields (0-20cm). A total of 5 topsoil samples in each field were taken using a stainless steel spade and mixed thoroughly. Afterwards the soil samples were chosen by quartation; Then plants’ debris and residues were removed. Finally soil samples were 0.3-mm sieved and stored in brown glass bottles at 4 °C.

The following was the area that the Florida soil was collected.

 

 

2. Is the explanation of χ is for molecular connectivity indices or branching index?

R: It has been mentioned in L163-164 in the manuscript. Randic (1975) proposed molecular branching index χ, hereinafter referred to as simple molecular connectivity index (1995). Therefore, they are the same concept.

[38] Randic M., Razinger M. (1995). Molecular Topograhic Indices. Journal of Chemical Information and computer Sciences. 35: 140-147.

[40] Randic M. (1975). On Characterization of molecular branching. Am. Chem. Soc. 97: 6609-6615.

3. The values obtained of I DW and steric hindrance are not explained.

R: Accepted and revised in L157-160. Common topological indices, such as κ shape indices and information indices were also calculated by Molconn-Z (version 4.12S, eduSoft, La Jolla, CA). The detailed list and definitions can be found in the software user’s guide [35], and the definitions can also be found in Todeschini et al. [36]. The results of other common topological indices calculated by Molconn-Z were shown below as well. But in this study, only the steric index (R² = 0.82 for CN soil; R² = 0.86 for FN soil) and IDWbar (R² = 0.83 for CN soil; R² = 0.94 for FN soil) have a better relationship with the half lives of the isomers, which were mentioned in the Results and Discussion part.

The results of the topological indices of the isomers

[35] Hall, L. H.; Kellogg, G. E.; Haney, D. N. (2008). Software Package for Molecular Topology Analysis User’S Guide.

[36] Todeschini, R.; Consonni, V.; Mannhold, R.; Kubinyi, H.; Folkers, G. (2009). Molecular Descriptors for Chemoinformatics; Wiley: New York.

 

4. The more critical issue lies in the analytical methodology used for isomers quantification. First of all, figure one is a chromatogram, not a spectrum. The chromatogram is not well resolved, i.e., there is no separation among the different analytes determined. For example, look at peaks 4, 5, and 6. There is no resolution among the isomers, the same for NP 7 and 8 and NP 8 and 10; thus, it is impossible to quantify them.

If correct quantification is not assessed, then figure 1 and table 1 and 2 are not valid.

R: The analytical methodology of isomers quantification has been studied and published in former study (Wang et al., 2013). From Figure1 in Supporting Information, it seems that the isomers were not separated, but actually it does not affect the quantification of the isomers. Because the main quantitative ions were used for quantification and the main quantitative ion of each isomer were separated absolutely (Figure 1). Table 1 and Figure 1 were cited from Wang et al (2013). Moreover, series of research about the NP isomers were conducted and published afterwards. The following are the publications.

 

1. Shiyu Wang, Wenyong Wu*, Fei Liu, Shiyang Yin, Zhe Bao, Honglu Liu. Spatial distribution and migration of nonylphenol in groundwater following long-term wastewater irrigation. Journal of Contaminant Hydrology,2015,177-178（June–July）:85-92.
2. Shiyu Wang, Fei Liu*, Wenyong Wu*, Yaqi Hu, Renkuan Liao, Gaoting Chen, Jiulong Wang, Jialin Li. Migration and health risks of nonylphenol and bisphenol A in soil-winter wheat systems with long-term reclaimed water irrigation. Ecotoxicology and Environmental Safety 158 (2018) 28–36.
3. Shiyu Wang，Wenyong Wu*，Fei Liu, Xiaoou Li. Sorption and desorption behaviours of 4-nonylphenol on reclaimed water-irrigated soils. Environmental Engineering Science. (2019) 36 (9) : 1100-1111。
4. 王世玉，刘菲*，刘玉龙，陈亮. 气相色谱-质谱法检测地下水中12种对壬基酚同分异构体.分析化学，2013，41（11）：1699-1703.
5. 王世玉，刘菲*，吴文勇，尹世洋，刘玉龙，陈亮，张伟，陈会会.影响12种壬基酚同分异构体液液萃取效率的因素研究. 岩矿测试，2014，33（4）：570-577.

 

Your careful review of this manuscript is highly appreciated. I am looking forward to the good news. Please feel free to contact me if any questions.

 

Yours sincerely,

Shiyu Wang

[email protected]

Reviewer 2 Report

The authors revealed the Structure–biodegradability relationship of nonylphenol isomers in two soils sampled from long-term reclaimed water irrigation field in both China and America. This work sounds interesting and novelty. The manuscript can be accepted after minor revision.

 

1. The basic physi-chemical parameters of soils should be given.
2. The irrigation water physi-chemical parameters should be given.
3. The kinect models should be given.
4. Figure 1 should be revised according to kinect model
5. I strongly recommend the authors to analysis the biomass of the soil samples.

Author Response

Reviewer #2:

1. The basic physi-chemical parameters of soils should be given.

R: It has been given in Supporting Information 2. Indeed, the characteristics of the soil are too limited. The main reason is that this experiment was conducted during my being in University of Florida, USA as a visiting scholar. My visiting time was only one year. At the end of the visiting time, I had no time to complete the microbiological test and the soil properties detection and was going to leave the United States. Worse more, the soil can not be brought to China. So I had to acquire the Florida soil properties information by website. However, the information I can acquire from the website was limited, which were shown in Supporting Information 2.  

2. The irrigation water physi-chemical parameters should be given.

R: I think it is a little difficult for me to acquire the irrigation water physi-chemical parameters of Florida, but I can acquire the NP load in China irrigation water, which were cited from my former study of Wang et al., (2015). Bu in this study, the irrigation water was prepared in Lab according to the max NP concentration in reclaimed water in the study area to simulate NP in reclaimed water in the actual environment.

Shiyu Wang, Wenyong Wu*, Fei Liu, Shiyang Yin, Zhe Bao, Honglu Liu. Spatial distribution and migration of nonylphenol in groundwater following long-term wastewater irrigation. Journal of Contaminant Hydrology,2015,177-178（June–July）:85-92.

3. The kinect models should be given.

R: It has been given in Table1.

4. Figure 1 should be revised according to kinect model.

R: Accepted and revised in Figure1. All the isomers were revised according to kinect model except some isomers, such as NP2 NP5 and NP11. The degradation of these isomers were stable within the former several days, which mentioned in the manuscript. So these former points conformed to first-order kinetic formula.

5. I strongly recommend the authors to analysis the biomass of the soil samples

R: Indeed, in this study, the analysis of biomass and microorganism of the soil samples is essential. But I did not do that. The main reason is that this experiment was conducted during my being in University of Florida, USA as a visiting scholar. My visiting time is only one year. At the end, I had no time to complete and analysis the microbial community and biomass of the soil samples. Worse more, the soil can not be brought to China. But in the further study of the NP isomers in reclaimed water soil, this should be taken into account.

Your careful review of this manuscript is highly appreciated. I am looking forward to the good news. Please feel free to contact me if any questions.

 

Yours sincerely,

Shiyu Wang

[email protected]

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

It is fine in its present form. 

It can be published.

Best regards.

Author Response

Dear Editor：

Thank you very much for the comments of my manuscript. I have carefully read the comments and made a revision. The following are the details of the revision and marked red in the “resubmit” version.

Comments

1. I do not understand why soil samples were 0.3 mm sieved. Moreover, in the subsequent sentence is reported: "The soil was 0.25 mm-sieved to remove large particles; and then weighed series of 10 g aliquots into 250 mL brown jars"
   Did you sieve the soil twice at 0.3 mm and then 0.25 mm? Why?
   The active soil components (lime, sand, clay) where microorganisms live and organic carbon is accumulated is just less than 2mm. Consequently you excluded an important part of the active soil from your study, therefore your resuts are very limited.
   R： Actually, the soil samples were 0.25 mm sieved. At first, the soil was 0.3 mm sieved, but the big particle size was not appropriate for the soil ultrasonic treatment of NP extraction. Therefore, 0.3mm-sieved soil was not used for the experiment(which has been deleted in the manuscript in L104). Then the soil was 0.25mm-sieved, which was suitable for the NP extraction. If the soil was 2 mm-sieved, the extraction of the NP was more inappropriate. So 0.25mm sieve was used in this study. Indeed, this size particle excluded an important part of the active soil where microorganisms live and organic carbon is accumulated. But for this study, the degradation was completed within 30 days in both of the two soils. Therefore, though some of the organic carbon was adsorbed on the surface of the particle, the amounts of the microorganisms are enough for the degradation of NP. However, the degradation rate could be affected by this. In the future study, this would be taken into accounted. What’s more, the microbial community could be taken into accounted as well.
2.  
   Figure 1 legends of axis need font size larger, please make readable the figures
   R：Accepted and revised in L204. Figure 1 has been changed in the manuscript.

Your careful review of this manuscript is highly appreciated. I am looking forward to the good news. Please feel free to contact me if any questions.

 

Yours sincerely,

Shiyu Wang

[email protected]

 

Author Response File: Author Response.docx

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.