Quantification of Nitrate Level in Shallow and Deep Groundwater Wells for Drinking, Domestic and Agricultural Uses in Northeastern Arid Regions of Saudi Arabia

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The submitted paper titled “Quantification of nitrate level in shallow and deep groundwater wells for drinking, domestic and agricultural uses in north-eastern arid regions of Saudi Arabia” provides research on nitrate concentrations in groundwater of Saudi Arabia. Groundwater samples from treated and untreated stations for drinking water were collected and analyzed. The manuscript is well written, however some critical information about the study area is missing.

 

 

My recommendation is minor revisions.

 

General comments

- Abstract needs to be improved. Avoid mentioning general information. Provide the importance of this approach and its results.

- Avoid using keywords that are already in the title.

- Add information about the aquifers of the region. Hydrogeological data are missing. Try to provide a thorough approach based on the hydrogeological regime of the study area.

- Provide the innovation of the study.

-Provide future steps to improve the current work.

- The literature is poor. Please check the suggested papers below to improve the introduction. These works are about other approaches for investigating nitrate in groundwater and the optimum selection of sampling points in an area.

 

Suggested literature

Origin, implications and management strategies for nitrate pollution in surface and ground waters based on a δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻ isotope approach. Science of the Total Environment. 724, 138211.

Application of judgmental sampling approach for the monitoring of groundwater quality and quantity evolution in Mediterranean catchments. Water 15(22), 4018.

Mapping specific groundwater nitrate concentrations from spatial data using machine learning: A case study of chongqing, China. Heliyon, 10, 6.

 

Application of full-scale aerobic granular sludge technology for removing nitrate from groundwater intended for human consumption, Journal of Water Process Engineering, 57.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The subject is interesting and falls under the scope of the journal Limnological Review, where this paper approaches a subdiscipline of environmental application of water, characterizing the groundwater from northeastern of Saudi Arabia, and present strategies to reduce nitrate levels.

The work seems to be useful in terms of investigation into the studied area, has its originality, presenting new information with unknown results and not published content. Besides, it provides great added value data for the research field.

The introduction and methodology are well explained, as well as the studied area and the objective of the research, where authors included other works to support the necessity of the research and its goals.

Although, few improvements can be done regarding the template instructions for Equations (page 6), Figures (pages 7, 9, 10), and Tables (page 8), in addition to references with(out) DOI.

Also, results and discussion sections should be very descriptive, needing more comparisons with other works which have done similar works around the world. Explanations observed and different results by other scientific publications, on similar matters should be analyzed. It will enrich your manuscript.

Besides, authors can highlight the limitations and future investigation based on what have been presented in conclusions, which is excellent for other researchers and science.

Comments on the Quality of English Language

Minor revision.

Author Response

Please take a look at the file I've attached here.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

 

Too high nitrate in water is a serious risk. Therefore efforts to reduce nitrate concentrations are welcome. It is possible to reduce the use of nitrate and other nitrogen compounds so that their leaching will be lower. Nitrate in water can also be reduced for instance by using nitrate reducing microorganisms which metabolize nitrate finally to elementary nitrate gas.  The reaction can happen in tank or in wells. Often is it need a carbon source.    

The message of this manuscript is to describe the commercial nitrate analyze basing on Griess reagent, which is already more than 150 years old. Thus the novelty of this manuscript is low.  The technique can often be improved, but any improvement development by authors is not presented.  The accuracy of analyze is limed how exactly the 1 mL of sample is measured. Instead of volume the weight is often more accurate. Volume is dependent on temperature (not presented).

Together 13 well waters have been analyzed before and after the treatment, but this treatment is not described. Thus also the novelty of the treatment is not clear. There are also analyses about none treated wells, but in scientific papers these are many related results.

If there is a treatment method which is effective, present that, but you must have many more samples and you must desribe these samples.

Author Response

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Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

1. When making nitrate analyses, the major source of errors in the used method may be caused the size of test water. The 20 mL can be 19.5 or 20.5 mL. Temperature has its inbluence on volume. In addtion, if there can be even one week from sampling to analysis, there can be some degradation of nitrate.  

2. In the next works, concentrate how you could reduce nitrate concentrations in groundwater. SOme methods could be a better sanitation, which would use less water or a part of sanitation wastewater with its fertilizers could be used as irrigation water. In addition, nitrate can be reduced in a tank.   Please, comment these!

Author Response

Please take a look at the file I've attached here.

Author Response File: Author Response.docx

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

Totally the content is rather low if we think about the need of water-consumers, since the too high nitrate concentration is a risk for human - especially for babies. 

But this material do not contain any other data.