the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 07 Mar 2025
Isotopic evidence for the impact of artificial snow on the nitrogen cycle in temperate regions
Abstract. As winters become warmer due to climate change, ski resorts around the world are increasingly and preferentially relying on artificial snow instead of natural snow. The chemical species contained in artificial snow can flow into the surrounding hydrological system along with melted snow, resulting in unexpected environmental pollution. This study is the first attempt to assess the impact of artificial snow on groundwater quality and its role in the nitrogen (N) cycle. Although numerous multi-isotope approaches exist for identifying sources and estimating the contributions to nitrate pollution, few studies have used nitrogen isotopes of nitrate (δ15N–NO3−) and oxygen isotopes of water (δ18O–H2O) simultaneously as tracers. This study aimed to evaluate the impact of artificial snow on the quality of surrounding groundwater at a ski resort, located in Mt. Balwang in Pyeongchang, South Korea (the 2018 Winter Olympics venue). Mt. Balwang, located in the upstream region of the Han River, is a critical source of water that joins major tributaries forming the upper Han River, which supplies drinking water to over 25 million residents in the metropolitan Seoul area. The average N contribution of mountain groundwater estimated using Bayesian mixing models was the highest from artificial snow (49.5 %), originating from manure and sewage, exceeding rainfall (31.6 %) and natural snow (18.7 %). These results are closely consistent with theoretical N loading rates, highlighting the potential for artificial snow to contribute to long-term N accumulation in alpine ecosystems. Our study highlights the importance of continuous monitoring to mitigate potential disruptions to the N cycle and preserve ecosystem stability as climate change increases dependence on artificial snow.
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RC1: 'Comment on egusphere-2025-190', Anonymous Referee #1, 21 May 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-190/egusphere-2025-190-RC1-supplement.pdfCitation: https://doi.org/
10.5194/egusphere-2025-190-RC1 -
RC2: 'Comment on egusphere-2025-190', Joel Savarino, 30 Sep 2025
Review of Isotopic evidence for the impact of artificial snow on the nitrogen cycle in temperate regions by Hyejung Jung et al.,
The manuscript addresses an interesting and innovative idea, namely measuring the impact of artificial snow produced in ski resorts on the hydrological cycle using isotopic tools. While the basic idea is innovative and the manuscript deserves to be published in another context, unfortunately the statistical treatment and the approach taken by the authors contain too many errors of interpretation and analysis to garanti its publication.
After reading the manuscript, I came to the same conclusion as reviewer 1.
The points that seem to be deal-breakers for publication are:
The statistical approach appears to be very weak. Artificial snow was measured on only two samples, which eliminates any possibility of gaining insight into the natural variability of this artificial snow. The absence of variability thus makes it impossible to reliably determine a mixing pole. Similarly, isotopic measurements are given with accuracies that far exceed those of the analytical methods used. For example, isotopic values for nitrogen 15 cannot be given as 0.01 ‰ when the method has an accuracy of 0.5 ‰. It follows that all the variability interpreted and commented on by the authors is misinterpreted. There is also no evidence that the isotopic values of the different reservoirs remain constant over time. Not including isotopic fractionation for nitrate, which is a species that degrades, seems to be an unjustified simplification that needs to be justified beforehand.
The second point concerns the objective of the paper. As the reviewer rightly pointed out, the paper focuses much more on the composition of groundwater bodies than on the origin of the nitrogen in these same bodies. In this respect, the title of the article is misleading. It is not a question of determining the impact of artificial snow on the nitrogen cycle, but rather of determining the hydrological cycle of this mountain area. Like the first reviewer, I do not see how artificial snow could be a source of contamination, since it is itself produced from natural water collected in the same hydrological basin. The production of artificial snow (which is made with natural water, not artificial water) is at most a phenomenon of time lag in a hydrological load. This in no way corresponds to contamination.
It is surprising to see the paper evolve from an analysis of the nitrogen cycle to what ultimately becomes an analysis of the water cycle, where what is supposed to be determined by a combination of nitrogen sources becomes the sources themselves for determining the origin of groundwater. Clearly, the title of the article is inappropriate.
Unfortunately, the static weakness, the overinterpretation of the data, the confusion between contamination and flow displacement, and finally the change in the scientific question throughout the paper require too much rewriting for the paper to be accepted. It requires a complete rewrite with a paradigm shift from the nitrogen cycle to the hydrological cycle.
Below, I list the elements that led me to my assessment.line 29-30: authors should give a better context of their scientific question.
If snow is artificial, the water used for it is not artificial. they should better present why N in this natural water
is a problem.Line 31-42: poorly connected to N cycle, more about energy consomption. Biogeochemical cycle and climate change are two separate environmental issue, even if at some point they can be connected.
Line 49: volume of water used needs a comparison with some other human use.
Line 52: 3mg/L, need to give the variability to see how different it is from artificial snow
Line 71: only two artificial samples ! This is not enough to have a clear variability
Line 101 and 105: giving the precision of the methods, all data in the paper should be
consistant with these precisions. no data at 0.0x precision for water or 0.x for 18?N nitrate etc.Line 108: definition delta: remove x 1000, useless 0.006 or 6 ‰ is exactly the same number no need to x 1000
Line 150 LMWL give the definition
Line 152-153: how can exchange with all samples on the LMWL can give point off the line ?
Line 168: 17 ‰ for 18O nitrate rain is very low, why ? This point seem to be an outlier
Line 171-172: attribution with no discussion
Line: 174-175: attribution with no discussion
Line 179-180: attribution with no discussion
Bizarre to mention sources that does not exist in theis system.Line 184: the seasonal pattern is not very clear on the figure and seem very weak
Line 191: ad hoc explanation ?
Line 193: increased from 6.83‰ to 7.53‰ is it significant with a precision of ± 0.5 ‰ ?
Line 200: replace M&S by manure and sewage
Line 201: what polluants the author are talking about?
Line 204: replace contaminants by sources
Line 215: now snow and rain have become sources
Line : 219-222: why then these values are reported and were used for interpretation before?
Line 244: there is no source inputs from artificial snow as it is formed from natural water.
Table S2: how can artificial snow density be > 800 kg/m3 ??? strange, it is ice at this density
Table S1: can we consider earth snow chemistry different that groundwater ? How two analysis can be statistically representative ? Same for Table S3
Citation: https://doi.org/10.5194/egusphere-2025-190-RC2
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