A National-Scale Study of Polycyclic Aromatic Hydrocarbons in Surface Water: Levels, Sources, and Carcinogenic Risk

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The work is good, however, after careful investigation, it was found that the present work more worthy if the article is revised carefully with inclusions and paying attention to the following issues. I recommend the manuscript for Minor Revision. The authors reported pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in water and assessing the associated carcinogenic risks is crucial for improving public health. Low molecular weight PAHs were predominated, showing 3-ring PAHs abundant in the north, while 2-ring dominated in the south due to the distinction on energy consumption. Carcinogenic risk model revealed that the highest health risks existed in adults, followed by adolescents and children. Toxic concentration of BaP and the daily intake of water directly enhanced PAH carcinogenic.

Comments:

1.         Require eye-catching titles and keywords. It should be modified.  

3.         The mechanism of formation should be incorporated in the update manuscript.

4.         The authors are suggested to include a section with a comparative critical discussion.

6.         Include the scheme of preparation of both materials, also incorporate the formation

8.         The figures 2 and 3 should be discussed critically, include JCPDS numbers in the text and images.

9.         Add one Table with one comparative discussion on pollutants.

11.       figures 4, and 6 should be discussed critically and comparatively.

Comments on the Quality of English Language

Can be improve.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study analyzed the concentrations, sources, and health risks of PAHs in the surface water of the seven major river basins in China. The results revealed that 16 PAHs were consistently present in the surface water across China, and their concentrations exceeded those in other countries. 

the study is well designed, however, few minor question are follows. 

How the present study is different from the already reported studies (ref 1-5)? 

regarding the pollution sources? six sources are used

coal combustion, 

oil/gas combustion

industrial emissions

vehicle exhaust

biomass burning

petroleum emissions

how can we separate them? as nearly all are fossil fuels burning emissions?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This is a well written and thoughtful article that brings together a lot of important information about the distribution of PAH in seven main river basins across China. Some information that is missing is the seasonal distribution of PAHs and whether bioremediation methods are already in place in areas where PAH concentrations are highest. The article could also put the data reported in context of global distributions of PAHs that are discussed in Section 3.3, how the types of PAHs compare and how China is  putting into place methods of control and governance, together with what should be improved. This article could be very useful in guiding government policies on environmental control, and enhancing the discussion could be ueful.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscipt is focused on evaluating the amount, occurrence, types and sources of PAH in surface water in 7 river basins in China, and determining related risk of carcinogenicity.

The authors conducted an extensive research in terms of the occurrence and concentrations of PAHs found in the relevant areas to obtain a database, then performed an evaluation according to the described methodology.

The obtained data are evaluated in relation to the environmental standard for water quality.

The work contains very extensive supplementary materials, necessary for understanding the information, data and characteristics of the subject.

Autors describe the sub-processes and conditions that affect the occurrence/degradation of PAHs (lines 238-241). These processes resulting in effectually contradictory phenomena could be characterized and quantified in more detail from the literature data, as they have a large influence on the total PAH content in addition to the sources.

Claims regarding “PAHs with 2–4 rings mainly originated from the combustion of biomass and coal at medium to low temperatures”,... could be described in more detail (chemistry).

I appreciate that the authors compare the pollution found in China with other rivers/regions (section 3.3), which is very valuable and the assessments are impressive. This information could possibly be even more detailed in the text of the given focus.

Submitted findings, or calculated results from received data are well visualized and commented. In some places there is information duplication that could be eliminated.

Labels in Fig. 6 are small and rather difficult to read.

The article as a whole has an informative benefit and reflects the current topic in the form of environmental burden through a serious type of contaminants and calculates the resulting carcinogenic risk for children/teenagers/adults.

 Considering the above, I recommend a MINOR revision.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf