Typology of Environmental Impacts of Artisanal and Small-Scale Mining in African Great Lakes Region

Round 1

Reviewer 1 Report

Typology of Environmental Impacts of Artisanal and Small-scale Mining in African Great Lakes Region

This manuscript concerns a review paper on the environmental impacts of mining activities in Africa. This work is well written and clearly presented. The work herein presented is certainly within the scope of the Journal of Sustainability. I have a few major comments that should be addressed by the author before recommending this paper to be accepted.

Major comments:

- Lines 79-85: the impact of heavy metals in the natural course of the rivers should be linked with the topic of reservoir sedimentation [1]. The pollutants adhered to the sediments are conveyed downstream until reaching the reservoirs. This pause a major concern in African Great Lakes Region since an important percentage of the population relies on fishing as the main form of their economic activity.

- Lines 95-113: these lines describe the different techniques used to extract minerals from the alluvial channels. I would suggest to add and explain the work of [2] and link their physical insights. This work studied the sediment concentration-discharge patterns as a result of the contribution of distal and proximal sediment sources. Mining activities are strongly impacting the sediment dynamics: the different techniques used to extract minerals from the alluvial channels increased the natural sediment supply to the rivers. The resulting erosional and depositional processes are thus affected.

- Line 251: in the geomorphological processes I would add the following: the anthropogenic increased sediment supply of the rivers due to the mining activity causes a fining of the riverbed surface. As a result, the bed roughness is modified and this has implications in the sediment transport and the velocity/shear stress flow patterns. This was already studied in the field [3] and accordingly modelled in the laboratory and numerically in [4].

Bibliography

[1] Schleiss A.J., Franca M.J., Juez C. & De Cesare G. Reservoir Sedimentation – Vision Paper. JOURNAL OF HYDRAULIC RESEARCH. 2016. DOI: 10.1080/00221686.2016.1225320.

[2] C Juez, MA Hassan, MJ Franca. The origin of fine sediment determines the observations of suspended sediment fluxes under unsteady flow conditions. WATER RESOURCES RESEARCH. 2018, 1-16.

[3] Ferguson, R.I., Church, M., Rennie, C.D., Venditti, J.G., 2015. Reconstructing a sed- iment pulse: Modeling the effect of placer mining on fraser river, canada. J. Geophys. Res.: Earth Surf. 120, 1436–1454. doi: 10.1002/2015JF003491 .

[4] Juez, C., Battisaco, E., Schleiss, A.J. and Franca, M.J. Assessment of the performance of numerical modeling in reproducing a replenishment of sediments in a water-worked channel. ADVANCES IN WATER RESOURCES. 2016. DOI: 10.1016/j.advwatres.2016.03.010.

Comments for author File: Comments.docx

Author Response

Dear reviewer,

please, find the attached file. There are answers and comments to your review of my article.

Thank you very much for your review!

Best regards!

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript is a review summarizing the environmental impacts of small-scale mining activities, and it is considered as a valuable report that provides important suggestions on environmental protection while considering economic development.

Recently, The Minamata Convention has come into force and restrictions on mercury use will be imposed. The authors will be required to add short comment on the future effects on ASG activities after the convention.

Minor comments

Line 137: Is GT “Gross Tonnage” ?

The author mentions pollution of rivers and soils (for example, line 217-218). What kind of chemical substance is considered to be the pollution?

Line 440: Is the unit (µg/L-1) of Hg concentration µg/L or µg•L-1?

Author Response

Dear reviewer,

please, find the attached file. There are answers and comments to your review of my article.

Thank you very much for your review!

Best regards!

Author Response File: Author Response.docx

Reviewer 3 Report

The submitted article is interesting for a broader readership of Sustainability. It is well structured and adequately present research findings.

Author Response

Dear reviewer,

Thank you very much for your review!

Best regards!

Reviewer 4 Report

this subject is of broad environmental interest and has great potential impact on ecosystems and public health. data gathering for this report was by literature search (over very restricted time period) and from a number of interviews. the subject of artisanal and small scale mining ASM deserves a systematic and deep investigation for the potential to disrupt surface landforms.

i have serious concerns about the validity of the research methodology providing useful output.

restricted literature analysis - for a region with strong history of mining. particularly with limitation of identification of studies on ASM, then extension of this to wide regional scales

selection and collection of data from interviews - methodology including ethical approval is not described and the themes emerging and data collected are unclear.

the whole article makes very sweeping impactful statement about major effects including deforestation with little validation. data for deforestation is linked to many other processes as are other landscape disruptions from agriculture, urban development and historical changes in the locations.

no specific case studies are expanded on in detail to demonstrate direct effects.

the discussion in particular offers a series of discrete impacts and issues but these  are not backed up by the detail of methodology and direct data/examples. 

Author Response

Dear reviewer,

please, find the attached file. There are answers and comments to your review of my article.

Thank you very much for your review!

Best regards!

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The author took into consideration all my queries.

Author Response

Dear reviewer, thank you for all your queries!

Kind regards

Author

Reviewer 4 Report

the revision is much better and meets with comments made previously. the level of detail around the discussion of interview feedback is ok.

still need to check grammar and spelling.

details on methodology are still unclear. the expert selection is not confirmed and the level of detail derived from stakeholders is not clear.

I cannot get a feeling for the nature of information collected and transcribed. the interview process and rigor of that needs to be clearer. the methodology needs to show what where and when as far as data is concerned. the broad period of time (2012-2015) is not clear where and when interviews took place.

what does the "open and unstructured research plans were preferred" (line 63) mean for the data gathering?

what background did the 11 experts have and why were they selected?

Author Response

Dear reviewer, thank you for all your queries!

Please, see an attachment.

Kind regards

Author Response File: Author Response.docx