Hydrochemical Changes and Influencing Factors in the Dongkemadi Region, Tanggula Range, China

Round 1

Reviewer 1 Report

Please, find all relevant recommendations in the attached pdf review file.

Comments for author File: Comments.pdf

Author Response

all the grammatical problems were revised one by one in the text (in red) according to the reviewer's suggestions  (line 3, 17, 23, 38, 46, 47, 48, 108, 123, 124, 155, 179, 192, 213, 227, 228)

question 1: the time period of the data?

reply: it is the average value of the past decade, and we have revised it in the text (line 80)

Reviewer 2 Report

The authors provide a detailed hydrochemical record of river water, glacier melt and precipitation in the Dongkemadi  basin.  The comments below are generally asking for further comparison with what has been found in other basins, more seasonal analysis correlations work and  put the climate of 2014 in the larger perspective.  If the data allow it would be important to make a statement about the geographic origin of the precipitation by season.  Addressing the above will increase the importance of this study and its relevance beyond the study basin.

46: “There have been significant recent changes in alpine glaciers and river runoff because of  global warming.”

47: “In western China, 82.2% of glaciers have retreated, leading to a total area loss of 4.5% [7]. The Dongkemadi Glaciers were continuously losing mass after 1994, and this loss accelerated at the beginning of 2000 [8].”

49:  need to refer to the more recent research on Dongkemadi glaciers in Ke et al (2017). “Results show that the variation of glacier area over 1976–2013 is characterized by significant shrinkage at a linear rate of −0.31 ± 0.04 km2·year−1. Glacier retreat slightly accelerated in the 2000s, and the mean glacier surface elevation lowered at a rate of −0.56 m·year−1 over 2003–2008.”

63: “ This research could increase our understanding of….”

75:  Is this glacier runoff contribution percentage an annual or seasonal value?

79:  Is this temperature the average for the basin?  This equates to what elevation for the temperature values?  How did 2014 compare to other years?  Ke et al (2017) Figure 3 for example provides a comparative context.

89: “During the period June-October of 2014, 247 natural water samples were collected from the Dongkemadi basin (sample locations are shown in Figure 1): 148 were river water samples collected at 18:00 every day, 72 samples were atmospheric precipitation water and 27 were samples of glacier meltwater collected on the glacier. Each sample is collected by plastic basins which washed with ultrapure water, and pre-washed with precipitation immediately after each precipitation stops.”

97: “cryopreserved”

112:  Not sure on why the composition type is listed simply as “HCO- 3- Ca2+”?

120:  The key difference between precipitation and meltwater and the river water is the much lower concentration of cations and anions.

148:  Is the increase in TDS due to reduced dilution or increased contact time with sediments?

151:  Provide better description of acronyms in Figure 2 caption.

170: In figure 3 if the trend line are fit seasonally for summer versus post monsoon, are the correlations better for one season or the other?

185:  How does this compare to any other basin in the region?

197 “Dongkemadi basin…”

213: Can you quantify the carbonate rocks, silicate rocks and evaporite rocks relative importance better here, Figure 6 suggests evaporite rocks are a distant third in importance?

231:  What can be said about moisture source?  Note Tian et al (2007).

244:  Place the 3% ratio in perspective.

291:  Indicate what is consuming the CO2.

305:  It is important to identify the expected changes in ion concentration due to seasonal reductions in glacier runoff, due to reduced glacier area.

Ke, L.; Ding, X.; Li, W.; Qiu, B. Remote Sensing of Glacier Change in the Central Qinghai-Tibet Plateau and the Relationship with Changing Climate. Remote Sens. 2017, 9, 114.

Tian, L.; Yao, T.; MacClune, K.; White, J.W.C.; Schilla, A.; Vaughn, B.; Vachon, R.; Ichiyanagi, K. Stable isotopic variations in west China: A consideration of moisture sources. J. Geophys. Res. Atmos. 2007, 112.

Author Response

We have added a PDF file of all responses. 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have significantly clarified both the approach and the results.  I do suggest the authors consider adding a figure that provides a better visualization of the study area, see attached file as an example. The remaining comments are minor and are either rewording or asking for further clarification.

48: “lose” to “loss”

72: “..source region of the Yangtze River”

84: Remove “the glacier ablation”

90: Given the importance of the landscape it would be worth including a new figure.  Either a more comprehensive satellite image as the Landsat attached, or a more local image that captures the landscape well. The respective areas of high ion contribution could be labelled even.

97:  “…which are washed”

102: “…to allow for natural melting”.

117: “..in order of decreasing concentration is:…”

152:  “With runoff in the Dongkemadi basin decreasing continuously, dilution is reduced and contact time with sediments increases…”

170: “…the Cl- ion concentrations is….”

187:  Figure 4a indicates considerable spread in the Na/Na+Ca ratio for meltwater.  Does this have significance?  What explains this spread?

204:  “that the runoff ions”..this part of the sentence has an unclear meaning.

316: “With glacier retreat and glacier meltwater declining, the ratios of Na+/(Na+ + Ca2+) and Cl-/(Cl- + HCO-3) in the Dongkemadi River will decrease correspondingly.”

Comments for author File: Comments.pdf

Author Response

A PDF file has been attached.

Author Response File: Author Response.pdf