Application of a Novel Amendment for the Remediation of Mercury Mine Sites with Hydrologic Controls
Round 1
Reviewer 1 Report
Journal: Hydrology
Title: Application of a novel amendment for remediation of mercury mine sites with hydrologic controls
This manuscript is a Project Report, therefore I will review it in that light. The authors apply "MercLok" which is an amendment for the remediation of Hg from two sites of former Hg-mines in the area of California. The project report indicates that the remediation carried out at location 2 was satisfactory considering that the leached Hg concentration decreased below the legally prescribed values. The results also showed that the application of MercLok significantly reduced Hg concentrations at Site 1 as well, however, additional research and efforts are needed to implement remediation on the site.
Probably the authors are not allowed/do not want to define the composition of MercLok. Namely, it is known that sulphur-impregnated materials are promising for Hg immobilization. The authors characterized MercLok as environmentally friendly in Chapter 4.
Provide a price comparison of the new "MercLok" material against commercially available synthetic and natural used materials.
Have you determined the maximum sorption capacity of MerckLok toward Hg, Total Hg, Inorganic Hg and Organic Hg? Why am I asking? It is known that the mechanism of immobilization of organic and inorganic Hg is completely different. You get a 76-78% reduction of organic Hg in leachates. It would be good to define the sorption mechanism of organic and inorganic Hg on MercLok.
This is about in-situ remediation, more precisely reducing Hg leaching. Thus, Hg is continuously washed away, but also immobilized. How long does MercLok last? This is related to the maximum sorption capacity. When the MercLok is completely saturated, what then?
The leaching of Hg, total and inorganic and organic for saturated MerckLok should be investigated. You have defined that the mobility of leached Hg is reduced in the presence of MerckLok. However, does Hg leach from MerckLok under ambient or acid rain conditions?
Complement the manuscript in this sense.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript presented in this Project Report format is fascinating. Mining actors and environmentalists will wait for the results to be delivered. Some small things need to be fixed to improve the manuscript:
• The "MercLok" treatment was applied to capture and sequester Hg. Of course, under certain conditions (Hg saturation conditions), the amendment material can no longer absorb Hg. In section 4 m, the author only mentions "predict long-term stability across a range of soils and conditions." We suggest the author add information on how long the treatment with MercLok can last until the treatment needs to be renewed or added.
· In section 4, the basic ingredients and concentrations of each constituent of MercLok P-640 should be mentioned. If this is not possible, the author can only mention the main ingredients.• In section 5, the sampling timing should be stated so that the increase in the concentration of Hg absorbed by MercLok can be identified.
• Figure 3: the red line should be 1%?
Minor editing of English language is required.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Reviewer 3 Report
Add a table showing the complete physio-chemical characterization of the water samples
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Compared to the previous version, the manuscript has been improved and supplementary material has been added.Although, the authors did not provide answers to my comments in written form, I will accept the manuscript in this form.
