Potential Impacts to Wetlands and Water Bodies Due to Mineral Exploration, Pebble Copper-Gold Prospect, Southwest Alaska

Round 1

Reviewer 1 Report

The manuscript entitled ”Incomplete reclamation of mineral exploration drilling at the Pebble copper-gold prospect, Southwest Alaska, 2016: potential impacts to wetlands and water bodies” presents an interesting case study about the contamination issues associated to mining exploration. The authors collected a set of data in an area difficult to access to show an overview of the issues that are affecting to a pristine area in Alaska. I consider that the topic and the information are valuable and interesting for the reader.

My main concern is that the authors did not follow the style that is standard for scientific publications hindering the reading and the understanding of the message that wanted to be transmitted. My recommendations are oriented to improve the style of presenting data and facilitate the understanding of the manuscript for readers of all places in the world and not only locals knowing the study area.

1.       The location of the study area requires a map indicating where this area is in Alaska. The map presented in figure 2 is very difficult to visualize. The authors must do a much better version of it especially. This includes adding a legend with full description of all the elements presented in the map, remove any text that is not associated to the map (national geographic, TOPO! Map, etc), introduce the names and mark the areas of the different sectors  described in the text. In all cases the fonts must be readable.

2.       The figure and legend captions are too long. There are full explanations that are meaningless in most cases. The authors must resume the content of each figure caption as much as possible and if there is anything remarkable , include it into the text. This must be applied all the figure captions.

3.       The names and labels of the different sampling points are extremely confusing and I would say near impossible to follow for someone that has not been working in that region. A good example of this is the figure caption of Table 7. Here not only the names are difficult to follow but also there are different names for different agencies so each point might even have different codes! I understand that this is the official naming (and usually are these long codes in all places in the world) but to present the results for the scientific community, the names can be simplified to facilitate the reading. Then a table with equivalencies can be added in the supplementary material. Also changes of names by different agencies are not important in this case.

4.       The explanations about results are based on multiple table of data that are not easy to follow. My suggestion is that the authors elaborate the visualization of the results with figures that facilitate this. This can be with simple graphs where the  WQC are marked but also with location figures where the size of the dots can be the concentration measured in water. This would be an essential point to increase the quality of the manuscript. Tables with data can be put into the supplementary material.

5.       There are multiple figures (photos) in the text that are not really very meaningful in a scientific publication. A well that is with a valve failure, or photos that are not clear what they want to show are more appropriated content for a presentation where the author can explain what they want to show than for a publication. If the authors consider essential any figure (I don’t think that any of them was needed) should elaborate better them adding indicators of what they want to refer with arrows or marks and add scales.

6.       Small comments about local circumstances can be skipped. For example: if there was a storm is not interesting, if a well was or not artesian in a previous campaign is also not that relevant, it is clear that there are seasonal oscillation in nature related to groundwater everywhere. The same can be said about the material surrounding a well, or local observations of the authors. In a scientific publication, the authors must focus in facts that are well documented. The speculations based on local observation can be elaborated in the discussion section. It is very important that the authors checked the full manuscript, it is full of this type of mistakes.

7.       The content of each section should be adapted to the name of the section. Some sections are mixed, for example lines 156 to 159 start describing wells but then is speaking about the risk to snow machines and the regulations about the size of the wells… Is this really needed in a publication about the contamination due to mining exploration? In general, I would recommend to the authors to read the full paper trying to focus on what they want to say and not diverge with different discussions or facts that are irrelevant for the reader.

Other frequent mistake is to refer to negative facts that it is not clear why are they relevant. Example: Line 196. There are hundreds of potential sampling points, the authors sampled some of them, but here it is referred to specifically two points that were not sampled. Why is this so important? Would be needed then to explain why they didn’t sampled another few hundreds well in the region? Again, the authors should check the full manuscript considering this.

8.       A full list of samples, with the classification of each of them (pond, artesian well, sediments…) with presence in a location figure would be needed

9.       The section discussion looks more like a conclusion section. The discussion must use the data presented to support the findings. Right now just comment facts without the support of data (Example: Line 430). Other questions that can be discussed are based on the big amount of drilling that are in the region (Table 1) and how the small sample collected in this study can be used to extrapolate potential impacts at bigger scale.

10.   The section conclusions must resume the major findings of this study, right now it is more a section of future perspectives. The authors must support these conclusions with the data that they collected and be more quantitative. In the current state, this section could be included in the introduction since it is explaining well the problematic of the mining exploration in Alaska and the different contamination issues that can trigger.

11.   I don’t think that table 8 is needed.

12.   The appendix can be shortened. The petroleum chromatographs are not needed. 

13.   I think that the title can be improved. I don’t think that 2016 is needed and probably the study area name can be included between brackets. Something like: Potential impacts to wetlands and water bodies due  mineral exploration drilling (Pebble copper-gold prospect, Southwest Alaska)

14.   References to sources and photo credits are not common in scientific writing (specially when the photo is own by the same authors), use references instead and avoid photo credits by asking permission to the authors.

Author Response

Please see attachment

Author Response File: Author Response.docx

Reviewer 2 Report

This study is very comprehensive, thorough and interesting. For me a lot of new information about this type of "wastewater". 

Very good processing of individual chapters.

The chapters themselves are linked to each other, giving the work integrity.

Introduction provides a comprehensive view of the issue and attracts readers to read.¨

The text is supplemented with pictures that enrich the article with visual completion, which positively affects the reader. I rate very positively.

Results and conclusion are clear, concise and meaningful.

This thesis is supplemented with appendices, where are detailed analyzes from measurements. I I rate very positively.

Quantity of references is optimal.

Author Response

We thank the reviewer for his time and positive comments!

Reviewer 3 Report

The manuscript environments-529456 concerns the geochemical monitoring of mine water to evaluate the incomplete reclamation of mineral exploration drilling (Pebble copper-gold prospect, Southwest Alaska).

Comments:

Fig. 2: add a small Alaska map in which the study area is located.

I suggest to add a new figure regarding a cartoon-sketch in which the main geochemical processes described in the manuscript are synthetized.

Reword the conclusions with the key-point approach.

I read carefully the manuscript and I think it can be accepted with minor revision.

Author Response

Comments:

Fig. 2: add a small Alaska map in which the study area is located.

We have added a new map of the general area of Alaska and an inset of the mine area.

I suggest to add a new figure regarding a cartoon-sketch in which the main geochemical processes described in the manuscript are synthetized.

We have added the equation for acid mine drainage to help readers.  We have not added a cartoon sketch but tried to highlight the routes of contamination:  artesian waters picking up metals as they move up drill stems to the surface, possible drilling waste leaching into pond water and a wetland spring. If the reviewer or editor thinks the manuscript would be improved with a sketch we will attempt that.

Reword the conclusions with the key-point approach

We have revised the conclusions.

Round 2

Reviewer 1 Report

Good job with the review