Enrichment of Metals in the Sediments of an Industrially Impacted Estuary: Geochemistry, Dispersion and Environmental Considerations

Round 1

Reviewer 1 Report

The manuscript is interesting and fits well the scopes of Applied Scienes. The topic is useful from a scientific point of view. Generally, the paper is well described, however some corrections are needed. Please see my specific comments below.

1.  The samples were digested with aqua regia, without the use of HF. In this situation, the silicates did not decompose. Were the samples filtered after digestion? It is also not emphasized that the “pseudototal” contents of metal were determined, not the total.

2. What interpolation method was used in the GIS?

3. The methodology does not describe statistical methods. I believe that the following information should be added:

 a)     Has the data distribution been checked? If so, by what method? Pearson's correlation coefficients indicate that the data were normally distributed. Was it really so?

 b)     Was the data autoscaled prior to PCA and CA?

 c)     What method of agglomeration and what measure of distance has been used in the CA?

 d)     Please, shorten the description of CF, PLI and ERI in the methodology. These are known indicators that are well described in the literature. References and a brief description will suffice.

 4.     Table 1 and through manuscript: please, correct the number of significant digits.

Author Response

Reviewer 1

1. The samples were digested with aqua regia, without the use of HF. In this situation, the silicates did not decompose. Were the samples filtered after digestion? It is also not emphasized that the “pseudototal” contents of metal were determined, not the total.

Agree with your comment. Samples were filtered before analysis and of course, the analyses are pseudototal as HF was not used. These facts have been added to the manuscript in the materials and methods section

2. What interpolation method was used in the GIS?

Thanks for your comment, the method was inverse distance weighted (IDW). This information has been added to the manuscript in the material and method section.

3. The methodology does not describe statistical methods. I believe that the following information should be added:
4. a)Has the data distribution been checked? If so, by what method? Pearson's correlation coefficients indicate that the data were normally distributed. Was it really so?

Thanks for your kindly suggestion. Information about the statistical analysis has been added to the text: “Statistical treatments comprised normality test like Anderson-Darling and Kolmogorov-Smirnov and Pearson's correlation analysis”.

1. b)Was the data autoscaled prior to PCA and CA?

Agree with your comment. Autoscaling of the data has been added to the text

1. c)What method of agglomeration and what measure of distance has been used in the CA?

Agree with your comment. Euclidean distance and ward's clustering method have been added to the text to report this information.

1. d)Please, shorten the description of CF, PLI and ERI in the methodology. These are known indicators that are well described in the literature. References and a brief description will suffice.

Agree with comments, these parts have been shortened in this new version.

4. Table 1 and through manuscript: please, correct the number of significant digits

Thanks for your comment. Throughout the manuscript we have always used two decimal places due to the concentrations of Hg that require this precision. Due to this and after reviewing the entire manuscript, we consider that the accuracy provided is correct and does not require a review so as not to bias the results. However, we appreciate your comment.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript: Enrichment of metals in the sediments of an industrially impacted estuary: geochemistry, dispersion and environmental considerations is intersting work, good organized and  documented in properly geochmical and statistical method. The chosen geochemical indices have been used to assessment of the risk of contamination of estuarian sediments near the city of Avilés, but the reasons why exactly these indices was used in this resaerches are not clear? It should be better explained. 

Detailed comments are as follows: 

1.       acceptable risk levels for the ecosystem  - please, explain the „acceptable risks” term used in abstract

2.       factorial coefficients – what doas it mean, exactly

3.       Metaloid term i=coincerning to metals: should be described separate in Chpts.  Discussion and Conclusions

4.       metal(oids) - metal(loids) - metals(oids) -  spelling should be corrected in all places – the terms should be also explained in the text, why the Authors discusssed the results  alltogether for metals and metaloids?

5.       anthropic source of contribution  – this term is not clear

6.       On the other hand   – replace some of these term becouse it is  repetedly used 

7.       „the most important risk of sediments is in the middle-internal area of the estuary where the presence of large amounts of fine-sized sediments with a significant contaminant load, can be a source of contaminants transference to the surrounding environment” – this sentence in Discussion does not rather make  sence: the fine-grain of materials is  depend on normal sedimentation and not on the risks of anthropogenic  contamination, and term „contaminant transference” in this case is not properly used

8.       Figure 3. – Legend to small letters

9.       The Figures included in  the supplementary materials are poor described. The proper legends (e.g. stars, red colour, yellov colour, SG abrev.)  are lacking.

10.   Figure 3 in supplementary materials are not visible, the legend description is enigmatic, what does mean:  "general" area? If description are in the text, please write it.

Author Response

Reviewer 2

The manuscript: Enrichment of metals in the sediments of an industrially impacted estuary: geochemistry, dispersion and environmental considerations is intersting work, good organized and  documented in properly geochmical and statistical method. The chosen geochemical indices have been used to assessment of the risk of contamination of estuarian sediments near the city of Avilés, but the reasons why exactly these indices was used in this resaerches are not clear? It should be better explained. 

Detailed comments are as follows: 

1. Acceptable risk levels for the ecosystem  - please, explain the „acceptable risks” term used in abstract

Thanks for your comment. Maybe the term “acceptable risks” is confused, we have changed it by “low risk”.

2. Factorial coefficients – what doas it mean, exactly

Agree with your comment. The proper term is “factorial weights”. We have changed in this version

3. Metaloid term i=coincerning to metals: should be described separate in Chpts.  Discussion and Conclusions

Agree. done

4.Metal(oids) - metal(loids) - metals(oids) -  spelling should be corrected in all places – the terms should be also explained in the text, why the Authors discusssed the results  alltogether for metals and metaloids?

Agree with your comment. The term metal(oids) was used in all of the text.

1. Anthropic source of contribution  – this term is not clear

Thanks for your comment. This sentence has been rephrased.

6. On the other hand   – replace some of these term becouse it is  repetedly used 

Agree for your comment. We have removed this term in some part of the manuscript.

7. „the most important risk of sediments is in the middle-internal area of the estuary where the presence of large amounts of fine-sized sediments with a significant contaminant load, can be a source of contaminants transference to the surrounding environment” – this sentence in Discussion does not rather make  sence: the fine-grain of materials is  depend on normal sedimentation and not on the risks of anthropogenic  contamination, and term „contaminant transference” in this case is not properly used

Agree with your comment. This sentence has been rephrased.

8. Figure 3. – Legend to small letters

Thanks for your comment. We have increased the size of the legends

9. The Figures included in  the supplementary materials are poor described. The proper legends (e.g. stars, red colour, yellov colour, SG abrev.)  are lacking.

Agree with your comment. A description of the legend has been added to the figures.

10.  Figure 3 in supplementary materials are not visible, the legend description is enigmatic, what does mean:  "general" area? If description are in the text, please write it.

Agree with your comment. Changes have been made in the Fig to increase the text size and also, description of the legend has been added.

Author Response File: Author Response.docx

Reviewer 3 Report

The research purpose of this paper is clear, and the whole content is well organized and clearly articulated. There are some innovations in this study, and some important results and conclusions have been drawn, which provide important scientific basis for local environmental management. Some suggestions are as follow:
Materials and methods: 1) Are the sampling locations and their densities random or do they follow any principles? 2) Did the authors conduct a field survey of relevant enterprises and their pollution characteristics in the study area and along the river? If yes, the survey information should be added; if not, the source of the relevant information should be described, as it is mentioned in the analysis of the spatial distribution of some heavy metals. 3) The company and model of ICP-MS should be given; and also 4) It should be specified whether these standard reference materials (RTC- CRM026-050, CRM042-056, OREAS 503c and MRGeo08) are soils, sediments or other substances.

Results and discussion: 1) The standard deviation is an important statistical parameter and its data should be presented in Table 1; 2) “This general distribution of predominant sizes in the different areas is indicative of the sedimentological dynamics of the estuary, which, in its inner-most part, tends to be a sink for materials from the coastal environment, not naturally exporting materials to the coastal environment.”——I am not so sure that this conclusion is correct. Such sedimentological dynamic characteristics in estuary and coastal environment can only indicate that river-source pollutants do not accumulate in coastal sediments due to the lack of stable deposition conditions, but the available data in this study do not confirm that these pollutants do not spread over long distances with seawater exchange or/and ocean current.

Author Response

Reviewer 3

The research purpose of this paper is clear, and the whole content is well organized and clearly articulated. There are some innovations in this study, and some important results and conclusions have been drawn, which provide important scientific basis for local environmental management. Some suggestions are as follow:

Materials and methods:

• Are the sampling locations and their densities random or do they follow any principles?

Thanks for your comment. It does not follow a homogeneous distribution since the objective was a general screening of the area trying to identify potential sources based on suspicions and the industrial activities carried out in the environment.

• Did the authors conduct a field survey of relevant enterprises and their pollution characteristics in the study area and along the river? If yes, the survey information should be added; if not, the source of the relevant information should be described, as it is mentioned in the analysis of the spatial distribution of some heavy metals.

Thank you for your comments, we are currently conducting this study and therefore it is not reported in this manuscript. In the text we reference the E-PRTR (Spanish Industrial Emissions Register) as a source of information for our discussion.

• The company and model of ICP-MS should be given; and also 4) It should be specified whether these standard reference materials (RTC- CRM026-050, CRM042-056, OREAS 503c and MRGeo08) are soils, sediments or other substances.

Agree. Done

Results and discussion:

• The standard deviation is an important statistical parameter and its data should be presented in Table 1;

Done

• “This general distribution of predominant sizes in the different areas is indicative of the sedimentological dynamics of the estuary, which, in its inner-most part, tends to be a sink for materials from the coastal environment, not naturally exporting materials to the coastal environment.”——I am not so sure that this conclusion is correct. Such sedimentological dynamic characteristics in estuary and coastal environment can only indicate that river-source pollutants do not accumulate in coastal sediments due to the lack of stable deposition conditions, but the available data in this study do not confirm that these pollutants do not spread over long distances with seawater exchange or/and ocean current.

Thank for your comment. In this case, we reaffirm this phrase because other studies in the area such as Sanz-Prada et al. (2020) or internal studies of the Port Authority (unpublished) support this hypothesis of not exporting to the coastal environment.