Spatial Assessment of Hydrochemical Characteristics and Evolution of Inferior Quality Water in Kashi Delta

Round 1

Reviewer 1 Report

Based on extensive hydrochemical measurements of groundwater, the manuscript discussed transformation of groundwater quality in Kashi Delta area. Despite the regional nature of the study, the topic of the manuscript is potentially interesting and useful. However, I have to say that the manuscript does not provide significant new insight and understanding of the discussed issue. The paper in its current form cannot be recommended for publication as some parts of it require supplementing and rewriting. The last remark relates primarily to the result and discussion sections.

I the results section the Piper diagram (Figure 4) is missing and the caption of the Figure 5 is incomplete. In explanation to Figure 5  the Authors should give information which chart corresponds to the analyzed ions. These deficiencies make it impossible to assess the Authors’ interpretation made and its substantive correctness.

In the discussion section some parts of the text are redundant and add nothing to discussion. For instance the lines 340-342 and 391-394 contain rather methodological content than discussion ones. Moreover, in some places the information in the body text is an exact repetition of the content contained in Table 6. Is Table 6 necessary then?

Minor defects found in the manuscript text:

1). The term "small geosphere ..." (line 97) is embarrassing. Geosphere is a solid part of the Earth and in  a narrower sense it is equated with lithosphere. So, it have rather planetary scale, not local;

2). Please, change “Distribution map” to “Location map” In caption to Figure 1;

3). How was ammonium nitrogen determined?;

4). What do the blue lines mean in Figure 2?;

5). In text the mean TDS concentration in the northern basin is 2,157.57 mg/L (line 218), but in Table 2 it is 2,159.57 mg/L, why?;

6). Whether descriptive statistics given in Table 2 apply to the southern and northern basins, or only to the northern basin?  ;

7). In chemical formulas proportionate numbers of the elements included in a compound should be given as subscripts. For instance: HCO₃, and not HCO3 (line 237); SO₄, and not SO4  (line 237). Please, check the entire manuscript;

8). Please, change the caption of Table 5. One caption to the table without division into a and b.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript “water- 1456212” aims to investigate the hydrogeological background of

 the Kashi region in China using  graphical and multivariate statistical methods in order to

 distinguish between high and poor-quality water.

The paper appears well-structured, however some sections must be improved.

I believe the manuscript should be published only after major revision.

Comments (P = page#/R = row#):

Add lithological map and section, add classification diagrams

P3

The section “Hydrogeology” must be coupled with lithological map and a geological section. Please add the map in the text improving the Figure 1. It can be useful to describe better the occurring processes.

P5/

Fig 2 is not clear. Please increase the size of the Legend and improve the figure (e.g. increase the size of samples and their codes).

P5/

Hydrochemical type- “When the mg equivalent weight of an ion 169 was in the range of 45–70% of the total isotropic ion mg equivalent weight, the ion was considered major”

More than 70% ?

P6

Results- Hydrochemical Characteristics

The results must be coupled with classification plots to make the information clearer to the readers.

Please add Triangular plots of major cation and anions adding also a Total Salinity plot (TIS). The samples can be divided in upstream and midstream and downstream samples. The authors can take inspiration from the following papers:

Fuoco, I., Figoli, A., Criscuoli, A., Brozzo, G., De Rosa, R., Gabriele, B., & Apollaro, C. (2020). Geochemical modeling of chromium release in natural waters and treatment by RO/NF membrane processes. Chemosphere, 254, 126696.

Apollaro, C., Di Curzio, D., Fuoco, I., Buccianti, A., Dinelli, E., Vespasiano, G., Castrignanò A., Rusi S., Barca D., Figoli A., Gabriele B. & De Rosa, R. (2021). A multivariate non-parametric approach for estimating probability of exceeding the local natural background level of arsenic in the aquifers of Calabria region (Southern Italy). Science of The Total Environment, 150345.

P 9-10

The Contour maps are not clear. Please add the unit in each legend and the reference of the mapping element must be reported in each image. Is not clear what element the first map (and others) represents.

Moreover, increase the size of numbers.

P13

Is the second equation corrected?

??²⁺⁽water)+??⁺(?????)+??⁺(?????) …..

P15

Add the following papers in the references list:

Fuoco, I., Figoli, A., Criscuoli, A., Brozzo, G., De Rosa, R., Gabriele, B., & Apollaro, C. (2020). Geochemical modeling of chromium release in natural waters and treatment by RO/NF membrane processes. Chemosphere, 254, 126696.

Apollaro, C., Di Curzio, D., Fuoco, I., Buccianti, A., Dinelli, E., Vespasiano, G., Castrignanò A., Rusi S., Barca D., Figoli A., Gabriele B. & De Rosa, R. (2021). A multivariate non-parametric approach for estimating probability of exceeding the local natural background level of arsenic in the aquifers of Calabria region (Southern Italy). Science of The Total Environment, 150345.

P16

Table 6

I suggest to calculate the Saturation Index (SI) respect to the phases of interest. This approach can make the discussion strongly supported by geochemical calculations.

NOTE:

• A spell check in all text is required.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The current manuscript investigated numerous hydrochemical parameters of groundwater and hydrogeological background of the Kashi region in China. To do so the authors obtained 128 confined and 18 phreatic water samples  from Kizil, Cakmak, and Tuman rivers in the north and the basins of the Gez and Kushan River. The samples were analyzed and several statistical methods like principal component, multivariate analysis and correlation analysis were employed by using the appropriate software (Surfer, Spss, Aquachem). The authors conclude that there was a wide-ranging spatial variability in the SO₄^2-, Cl^- and Ca²⁺ contents throughout the study area. Furthermore in some cases the nitrate and ammonium nitrogen concentrations exceeded the thresholds set by the drinking water standard of China. Finally the groundwater quality problems in the Kashi region should be explored using insights from the hydrochemistry perspective and be solved in conjunction with water quantity and other factors.

           The current work is very interesting, extensive and analyzed in depth by several statistical methods.  It additionally includes sampling over a large test area and the author’s conclusions may impact the quality of drinkable water. Thusly it is recommended to be published in Water. Although there are some issues that need to be addressed and a minor revision is advised.

• Lines 373-385: “Downstream of the southern basin…the intensive human activity there.” Elaborate here how the correlation between Ca²⁺ and Na⁺+K⁺ is caused by the human intervention. In upcoming lines (374-385) there is an attempt to explain that argument, but it is not clear enough how the heavy irrigation produces strong cation exchange and adsorption. The authors should try to expand a bit further here.
• Table 2b: “Matrix(Nouth)”. Probably the title of Table 2b should say “Matrix(South)”. Correct typo.
• Lines 463-466: “The maximum value … 2.55 times higher than the standard.” Something is not clear here. If the maximum value 0.51mg/L  refers to nitrate and ammonium nitrogen then it has surpassed much more than 27.3% the water standard of China. Since as it is mentioned later, it is 2.55 times higher than the standard. Make clear for which element the 0.51 mg/L refers to.
• Table 5a: The principle component analysis performed here indicate that the component two explains only a 12-13% of the total variance. The component two, includes NH⁴⁺ and NO^3-, which reflects mainly the human activity as mentioned later on (lines 441-442). This leads to the probably erroneous conclusion that out all of the variation in the hydrochemical factors only a small percent is caused due to human intervention. The authors should add a comment, anywhere they feel right, and to elaborate if the real extend of human intervention is only about 10% of the total problem in the water quality in the region. This is very important as will dictate the future actions to remediate the drinkable water.

Author Response

请参阅附件

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I accept the corrections and additions made by the Authors.

Reviewer 2 Report

Remarks from  reviewer have been correctly addressed, and the paper is now more focuse on his core topic
In my opinion it is now acceptable.
Best regards

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.