A Spatial–Seasonal Study on the Danube River in the Adjacent Danube Delta Area: Case Study—Monitored Heavy Metals

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors The practical significance and scientific novelty of the article raises a number of serious questions. Besides the computer model, what's new in monitoring? Chemical/biological oxygen consumption is correctly written as TsOD/BOD. This error needs to be fixed What industrial points or ores are there near the river? Are pollutants of technogenic origin? Comments on the Quality of English Language

normal

Author Response

 

Dear Reviewer,

Thank you for your comments and for helping write an improved paper.

 

The practical significance and scientific novelty of the article raises a number of serious questions. Besides the computer model, what's new in monitoring?

Answer: Thank you for the observation. 

Except for the numerical model presented, we would like to highlight the existence of some contributions of the main tributaries of the Danube in the study area. Such a systematic study has not been carried out due to conditions imposed by the border authorities.

From this point of view, this study has an element of originality.

On the other hand, the current study will also contain a second part that presents the spatio-temporal distributions of the chemical species that describe water quality indicators. The results will be used to carry out investigations regarding the distribution of habitats of community interest in the area.

The text was modified.

Chemical/biological oxygen consumption is correctly written as TsOD/BOD.

This error needs to be fixed.

Answer: Thank you for the observation. 

The text was modified.

 

What industrial points or ores are there near the river?

Answer: Thank you for the observation.  As it is mentioned, there are 2 shipyards and a steel plant (P1, P5 and P9)

 

 

 

Are pollutants of technogenic origin?

Answer: Thank you for the observation.  As it is mentioned, there are pollutants of technological origin.

 

Comments on the Quality of English Language

normal

Answer: Thank you for the observation.  the translation and the quality of expression in English was ensured by a specialized company

Submission Date

18 July 2024

Date of this review

26 Jul 2024 21:53:47

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In recent decades, the increasing impact of anthropogenic factors on aquatic ecosystems has led to the introduction of an increasing variety of pollutants. Therefore, it is now particularly important to carry out integrated environmental monitoring, which includes the study of physical, geochemical and biological aspects. The work of Catalina Tapa and her colleagues, which examines the dynamics of pollutant concentrations in the Danube's water and highlights seasonal variations, is therefore relevant and timely.
The article provides detailed information about the materials, research methods and experimental approaches that are essential for understanding the core of the work.

1. The title of the article is too long and complicated. In our opinion, it could be made more concise.
2. The abstract does not reflect the specific results of the study.
3. The names of chemical elements in the text and in Figures 8 and 10 should be replaced by their symbols.
4. Tables 7 and 8 can be included in the supplementary material. In our opinion, it is necessary to check the values of the significance level of the correlation coefficients in them.
5. There is no "Conclusion" section in the manuscript. Although it is not mandatory, "Conclusions" are often the last section and provide the final take-home message to your readers, so they are as important as introductions in research papers. They are your last chance to make a good impression on the reader.

Comments on the Quality of English Language

Some stylistic and grammatical revision is needed.

Author Response

Comments and Suggestions for Authors

In recent decades, the increasing impact of anthropogenic factors on aquatic ecosystems has led to the introduction of an increasing variety of pollutants. Therefore, it is now particularly important to carry out integrated environmental monitoring, which includes the study of physical, geochemical and biological aspects. The work of Catalina Tapa and her colleagues, which examines the dynamics of pollutant concentrations in the Danube's water and highlights seasonal variations, is therefore relevant and timely.

Dear Reviewer,

Thank you for your comments and for helping me write an improved paper.

The article provides detailed information about the materials, research methods and experimental approaches that are essential for understanding the core of the work.

1. The title of the article is too long and complicated. In our opinion, it could be made more concise.

Answer:

 Dear Reviewer

thank you very much for the suggestion. We would like to keep this title to be able to publish the rest of the results we obtained in this study and kindly ask you to accept this title.

2. The abstract does not reflect the specific results of the study.

Answer:

Thank you very much for the observation. We changed the abstract text. The changes are marked in red

 

3. The names of chemical elements in the text and in Figures 8 and 10 should be replaced by their symbols.

Answer:

Thank you very much for the observation. For a better understanding and to avoid any possible confusions, I kept the names of the elements

5. There is no "Conclusion" section in the manuscript. Although it is not mandatory, "Conclusions" are often the last section and provide the final take-home message to your readers, so they are as important as introductions in research papers. They are your last chance to make a good impression on the reader.

Answer:

Thank you very much for the observation. We changed the text and the conclusions are included.

 

Comments on the Quality of English Language

Some stylistic and grammatical revision is needed.

Answer: Thank you for the observation.  the translation and the quality of expression in English was ensured by a specialized company.

 

Submission Date

18 July 2024

Date of this review

03 Aug 2024 08:47:47

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Review of the paper:” A spatial-seasonal study for dynamics of pollutant concentration in water on the Danube River in the adjacent Danube Delta area and the evaluation of the attenuation and transfer  coefficients. Part 1 – case study – monitored heavy metals”.

The title of the paper is long and complicated. It should be shortened and corrected. In my opinion (I am not qualified to judge linguistic correctness), the wording " pollutant concentration in water on the Danube River " is not correct.

The article deals with an important issue. Unfortunately, the methodology and results of the work are not sufficiently described and presented. The article describes the variability of heavy metal concentrations. However, there is no mention of what standards for concentrations of these elements apply in surface waters. There is also a lack of comparison of the results of this study to other work on the water quality of the Danube or other rivers.

The article needs to improve the figures and be more careful in presenting the chemical parameters (description of these parameters), as well as improving the text.

The conclusion is also lacking.

 

Specific comments

1.      Introduction

Line 132: “In this respect, the aim tTo assess….”  ?

Shoul be: “In this respect, the aim to assess….” ?

2. Materials and Methods.

2.1. Data Collection

Please provide more details about the sampling locations. From what depth were the samples taken?

Line 159. Please explain the abbreviations CCO and CBO5.

Please improve the way you write throughout the article in the table below, only examples are given.

There is	Should be
NH4+	NH4+
SO42-	SO42-
Cl-	Cl-
NO3-	NO3-

 

2.2. Methodology

2.2.a Water and sediment sampling methodology

Describe the accuracy of the method and the uncertainty of the measurements.

2.2.c. Methodology for numerical analysis

Figure 2. Please provide the scale of the map.

3. Results

3.1. Statistical approach

Table 3,5. It would be better to present this data in graphical form (box plots).

Table 7, 8. Please mark which values are statistically significant. In the Statistica program, significant values are highlighted in red.

Figures: 4,5,6 and 7 are not comprehensible. It is not clear whether they represent the mean, mean ±SE mean ±SD. There are not box plots only scater plots. The y-axes should show the unit of measured values.

3.4. Numerical analysis.

Please explain and specify the values that were used for the numerical simulation. What were the values of the parameters: H, h, u, v, etc.?

Figure 11 shows only one value. Is it the mean ? The standard deviation is not shown.

Figure 12 a. What do the numbers in the table mean ? They are completely illegible.

2.      Discussion

Lines: 722, 733 and 734, should be corrected.

Comments for author File: Comments.pdf

Author Response

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

Quality of English Language

(x) I am not qualified to assess the quality of English in this paper
( ) English very difficult to understand/incomprehensible
( ) Extensive editing of English language required
( ) Moderate editing of English language required
( ) Minor editing of English language required
( ) English language fine. No issues detected

		Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?		( )	(x)	( )	( )
Is the research design appropriate?		( )	( )	(x)	( )
Are the methods adequately described?		( )	( )	(x)	( )
Are the results clearly presented?		( )	( )	(x)	( )
Are the conclusions supported by the results?		( )	( )	(x)	( )

 

Comments and Suggestions for Authors

Review of the paper:” A spatial-seasonal study for dynamics of pollutant concentration in water on the Danube River in the adjacent Danube Delta area and the evaluation of the attenuation and transfer  coefficients. Part 1 – case study – monitored heavy metals”.

Dear Reviewer,

Thank you for your comments and for helping write an improved paper.

 

The title of the paper is long and complicated. It should be shortened and corrected. In my opinion (I am not qualified to judge linguistic correctness), the wording " pollutant concentration in water on the Danube River " is not correct.

Answer:

thank you very much for the observation. We delete the word River.

The article deals with an important issue. Unfortunately, the methodology and results of the work are not sufficiently described and presented. The article describes the variability of heavy metal concentrations. However, there is no mention of what standards for concentrations of these elements apply in surface waters. There is also a lack of comparison of the results of this study to other work on the water quality of the Danube or other rivers.

Answer:

thank you very much for the observation. Sampling and sample analyzes for physico-chemical parameters were made according to the following Standard methods: SR EN 1899-2:2002 for BOD determination, SR EN ISO 11732:2005 for ammonium determination, SR EN ISO 6878:2005 for total phosphorus determination, SR EN 26777:2006 for nitrogen from nitrite determination, SR EN ISO 11905-1:2003 for nitrogen from nitrate determination, SR ISO 6332:1996/C91:2006—for iron total content, SR ISO 9297/2001—for chloride content, SR ISO 10566:2001—for lead content, SR ISO 9174-98—for Cr total, SR EN 16503:2015 - Guide standard for the evaluation of the hydro morphological characteristics of transient and coastal waters, SR EN ISO 10523 :2012 - - Water quality - Determination of pH; SR EN 16479:2014 Water quality. Performance requirements and compliance test procedures for water monitoring equipment. Automatic sampling devices (samplers) for water and waste water; SR EN ISO 5667-1:2007 - Sampling - Part 1: General guide for establishing sampling programs and techniques SR EN ISO 5667-1:2007/AC:2007 - Water quality - Sampling. Part 1: General guide for establishing sampling programs and techniques; SR EN ISO 5667-14:2017 - Water quality - Sampling - Part 14: Guide for quality assurance and quality control in the sampling and treatment of water from the environment. The research center is ISO accredited and is obliged to comply with European standards.

 

The article needs to improve the figures and be more careful in presenting the chemical parameters (description of these parameters), as well as improving the text.

Answer:

Thank you very much for the observation. We operated changes in figures and text – (the changes are marked in red).

The conclusion is also lacking.

 Answer:

thank you very much for the observation. The text was modified and the conclusion section was included.

 

Specific comments

1. Introduction

Line 132: “In this respect, the aim tTo assess….”  ?

Shoul be: “In this respect, the aim to assess….” ?

 Answer:

thank you very much for the observation. The text was corrected.

2. Materials and Methods.

2.1. Data Collection

Please provide more details about the sampling locations. From what depth were the samples taken?

 Answer:

Thank you very much for the observation.  The sampling depth was between 2.5 -4 meters from the surface.

 

Line 159. Please explain the abbreviations CCO and CBO₅.

 Answer:

Thank you very much for the observation.

For CB05 - Analysis method - electrochemical. Knowing the value of biochemical oxygen consumption per 5 days (CBO5) is extremely important in evaluating the degree of pollution of waste water expressing the amount of biodegradable organic substances contained in the respective water. Changes are operated in the text.

Please improve the way you write throughout the article in the table below, only examples are given.

There is	Should be
NH4+	NH4+
SO42-	SO42-
Cl-	Cl-
NO3-	NO3-

 Answer:

thank you very much for the observation.  All the changes were operated in the text.

 

2.2. Methodology

2.2.a Water and sediment sampling methodology

Describe the accuracy of the method and the uncertainty of the measurements.

Answer:

thank you very much for the observation.  Changes are operated in the text. The methods and the uncertainty of the measurements were the same as in our previous papers.

 

2.2.c. Methodology for numerical analysis

Figure 2. Please provide the scale of the map.

Answer:

Thank you very much for the observation.  Changes are operated in Figure 2.

 

3. Results

3.1. Statistical approach

Table 3,5. It would be better to present this data in graphical form (box plots).

Answer:

Thank you very much for the observation.  The team would prefer to keep the current form. references are made more easily in the exposition.

 

Table 7, 8. Please mark which values are statistically significant. In the Statistica program, significant values are highlighted in red.

Answer:

thank you very much for the observation.  Changes for significant values were made and the values were marked in red. However, the editor will request that these colors be removed (from previous experiences these color changes are irrelevant)

Figures: 4,5,6 and 7 are not comprehensible. It is not clear whether they represent the mean, mean ±SE mean ±SD. There are not box plots only scater plots. The y-axes should show the unit of measured values.

Answer:

thank you very much for the observation.  Changes for these figures were operated and were declared scatter plots.

3.4. Numerical analysis.

Please explain and specify the values that were used for the numerical simulation. What were the values of the parameters: H, h, u, v, etc.?

Answer:

thank you very much for the observation.

Figure 11 shows only one value. Is it the mean ? The standard deviation is not shown.

Answer:

thank you very much for the observation.  During the measurement campaign, for each period of one calendar month, the Danube flow variations and SE values are represented in figure 11.

Figure 12 a. What do the numbers in the table mean ? They are completely illegible.

Answer:

thank you very much for the observation.  Changes for this figure were operated.

2. Discussion

Lines: 722, 733 and 734, should be corrected.

Answer:

thank you very much for the observation.  Changes are operated in the text.

 

 

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

In this article, the authors present the results of study concerning the assessment of the seasonal variation in the concentrations of heavy metals (such as cadmium, chromium, arsenic, etc.) in the aquatic ecosystems of the Danube River Braila-Galati area.

The results are interesting and they showed that although there is an uneven distribution of the concentrations of heavy metals studied in the river bed, in areas where there are no point sources, the concentrations are relatively low and the habitats of community interest are not under pressure important.

The authors may refer to the following suggestions:

1.   At section 1. Introduction, Line 132-137, the aim of the study must be rewritten. It is specified that the potential use of local aquatic plants or fish species as bioindicators of environmental pollution was evaluated, which does not result from the content of the article.

2. At section 2.

 - Figure 1. The the map of monitoring points configuration and a broader regional map – you must correct the title and place sampling points P1, P2 on the map;

 -  At 2.2.c Methodology for numerical analysis you must present what was presented on page 22-23 (Line 610-655). It should also be explained how the distribution of the concentrations of the studied metals in the investigation area was determined.

3. The same measurement units must be used for Aluminum (µg/L) both in Table 2 and in Figure 4. (a) boxplot representation for aluminum concentration seasonally measured in the 10 monitoring points.

4. tables 7 and 8, the values ​​of the parameters must be mentioned correctly, for example: it will be used:

Al:   0.4386;  0.4822;  0.3696;  0.2077; 0.3736

       p=0.205;  p=0.158;  p=0.293

5. The Conclusions chapter is missing

6. The list of bibliographic references must be revised, there are mistakes in presenting the bibliographic sources..

The text of the work is very extensive, it contains some aspects that could be eliminated. Some paragraphs should be rewritten. The work requires a revision from the point of view of the English language and technical editing requirements.

Author Response

pen Review

( ) I would not like to sign my review report
(x) I would like to sign my review report

Quality of English Language

(x) I am not qualified to assess the quality of English in this paper.
( ) The English is very difficult to understand/incomprehensible.
( ) Extensive editing of English language required.
( ) Moderate editing of English language required.
( ) Minor editing of English language required.
( ) English language fine. No issues detected.

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	(x)	( )	( )	( )
Is the research design appropriate?	( )	(x)	( )	( )
Are the methods adequately described?	( )	( )	(x)	( )
Are the results clearly presented?	( )	(x)	( )	( )
Are the conclusions supported by the results?	( )	( )	(x)	( )

Comments and Suggestions for Authors

In this article, the authors present the results of study concerning the assessment of the seasonal variation in the concentrations of heavy metals (such as cadmium, chromium, arsenic, etc.) in the aquatic ecosystems of the Danube River Braila-Galati area.

Dear Reviewer,

Thank you for your comments and for helping write an improved paper.

 

The results are interesting and they showed that although there is an uneven distribution of the concentrations of heavy metals studied in the river bed, in areas where there are no point sources, the concentrations are relatively low and the habitats of community interest are not under pressure important.

The authors may refer to the following suggestions:

1. At section 1. Introduction, Line 132-137, the aim of the study must be rewritten. It is specified that the potential use of local aquatic plants or fish species as bioindicators of environmental pollution was evaluated, which does not result from the content of the article.

Answer:

Thank you very much for the observation. We operated the suggested changes

2. At section 2.

 - Figure 1. The the map of monitoring points configuration and a broader regional map – you must correct the title and place sampling points P1, P2 on the map;

Answer:

Thank you very much for the observation. We operated the suggested changes

 

 -  At 2.2.c Methodology for numerical analysis you must present what was presented on page 22-23 (Line 610-655). It should also be explained how the distribution of the concentrations of the studied metals in the investigation area was determined.

Answer:

Thank you very much for the observation. We proceeded as in our previous papers, using HECRAS and ArgGIS Network analyst tool. The entire procedure is explained and demonstrated in [14] and [ 19]

3. The same measurement units must be used for Aluminum (µg/L) both in Table 2 and in Figure 4. (a) boxplot representation for aluminum concentration seasonally measured in the 10 monitoring points.

Answer:

Thank you very much for the observation. We operated the suggested changes

4. tables 7 and 8, the values of the parameters must be mentioned correctly, for example: it will be used:

Al:   0.4386;  0.4822;  0.3696;  0.2077; 0.3736

       p=0.205;  p=0.158;  p=0.293

Answer:

Thank you very much for the observation. We operated the suggested changes

 

5. The Conclusions chapter is missing
6. The list of bibliographic references must be revised, there are mistakes in presenting the bibliographic sources.

Answer:

Thank you very much for the observation. We operated the corrections on references list.

 

The text of the work is very extensive; it contains some aspects that could be eliminated. Some paragraphs should be rewritten. The work requires a revision from the point of view of the English language and technical editing requirements.

Answer: Thank you for the observation. 

The text of the work is very extensive because it was a huge amount of work of our team for these results. The translation and the quality of expression in English was ensured by a specialized company

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Review of the paper:
“A spatial-seasonal study for dynamics of pollutant concentration in water on the Danube in the adjacent Danube Delta area and the evaluation of the attenuation and transfer coefficients. Part 1 – case study – monitored heavy metals”
The title of the paper is long and complicated.
In my opinion, it has not been properly corrected. The expression “Danube River” should stay.
The article has been corrected, but it needs careful linguistic and stylistic correction.
Figures and tables captions should begin with a capital letter.
Please correct: Table 1, Figures 4-7, 11-16.
Please correct:
“Figure 1. The the map of monitoring points configuration and a broader regional map.”

Comments for author File: Comments.docx

Author Response

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

Quality of English Language

(x) I am not qualified to assess the quality of English in this paper.
( ) The English is very difficult to understand/incomprehensible.
( ) Extensive editing of English language required.
( ) Moderate editing of English language required.
( ) Minor editing of English language required.
( ) English language fine. No issues detected.

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	(x)	( )	( )	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	( )	(x)	( )	( )
Are the results clearly presented?	( )	(x)	( )	( )
Are the conclusions supported by the results?	(x)	( )	( )	( )

Comments and Suggestions for Authors

Review of the paper:
“A spatial-seasonal study for dynamics of pollutant concentration in water on the Danube in the adjacent Danube Delta area and the evaluation of the attenuation and transfer coefficients. Part 1 – case study – monitored heavy metals”
The title of the paper is long and complicated.
In my opinion, it has not been properly corrected. The expression “Danube River” should stay.

Answer

thank you for observation.

The article has been corrected, but it needs careful linguistic and stylistic correction.
Figures and tables captions should begin with a capital letter.

Answer

thank you for observation.  We operated the corrections

Please correct: Table 1, Figures 4-7, 11-16.
Please correct:

Answer

thank you for observation.  We operated the corrections

 “Figure 1. The the map of monitoring points configuration and a broader regional map.”

Answer

thank you for observation.  We operated the corrections

 

peer-review-39584136.v1.docx

Submission Date

18 July 2024

Date of this review

20 Aug 2024 08:50:09

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

It's Ok. Attention at References, you must verify  poz. 2, 35, 57 (you must utilise lowercase)

Author Response

 

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

Quality of English Language

(x) I am not qualified to assess the quality of English in this paper.
( ) The English is very difficult to understand/incomprehensible.
( ) Extensive editing of English language required.
( ) Moderate editing of English language required.
( ) Minor editing of English language required.
( ) English language fine. No issues detected.

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	(x)	( )	( )	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	(x)	( )	( )	( )
Are the results clearly presented?	(x)	( )	( )	( )
Are the conclusions supported by the results?	(x)	( )	( )	( )

Comments and Suggestions for Authors

It's Ok. Attention at References, you must verify  poz. 2, 35, 57 (you must utilise lowercase)

Answer:

thank you for observation. We corrected the list of references.

 

Submission Date

18 July 2024

Date of this review

20 Aug 2024 08:42:16

 

Author Response File: Author Response.pdf