Preprints
https://doi.org/10.5194/egusphere-2024-789
https://doi.org/10.5194/egusphere-2024-789
12 Apr 2024
 | 12 Apr 2024

Massive mobilization of toxic elements from an intact rock glacier in the Central Eastern Alps: insights into ice melt dynamics

Hoda Moradi, Gerhard Furrer, Michael Margreth, David Mair, and Christoph Wanner

Abstract. In the Central Eastern Alps, an increasing number of high-altitude streams display high concentrations of toxic solutes such as Al, F-, Mn, and Ni that may strongly exceed drinking water limits. Previous studies have shown that these elements are mobilized from rock glaciers occurring at the origin of the streams. This is caused by the weathering of pyrite producing sulfuric acid and therefore promoting the leaching of these elements from the crystalline host rocks. After mobilization, the elements are temporally stored and enriched in the rock glacier ice. Today, the climate-change-induced accelerated melting of rock glaciers thus leads to a quick and focused export in summer when ice melt export rates are high. The temporal storage of mobilized elements in the rock glacier ice opens up the opportunity to use the strong chemical signal in the streams to track rock glacier melt dynamics and to identify the governing processes controlling the export of ice melt. To test this and to assess the consequences of accelerated rock glacier melt on streamwater quality, here we present a two-year dataset (2021, 2022) of monitoring a high-alpine stream originating from an intact rock glacier located in Eastern Switzerland. The monitoring includes monthly sampling and discharge measurements at the rock glacier outlet, as well as continuous tracking of the geogenic fluxes of toxic solutes using a pressure and conductivity probe. Our monitoring revealed high annual fluxes with strong seasonal variation, whereby the fluxes were highest during the warm summer months. In 2021, the annual fluxes were up to several tons each, which is remarkable given that the area of the rock glacier covers only about 40’000 m2. Interestingly, in 2022 the fluxes were about 30 % lower despite the record-high summer temperatures. A similar difference was observed for the annual discharge recorded for the two years. This suggests that the export of both ice melt and toxic solutes are strongly controlled by the amount of water from snowmelt and precipitation infiltrating into the rock glacier system. The dry weather and low discharge rates in 2022 thus likely lead to lower export rates compared to 2021, when snow height and precipitation rates were above average. Nevertheless, in both monitoring years the degradation of the rock glacier significantly contributed to the discharge of the downhill stream. Based on these aspects, we present conceptual models for accumulation of toxic solutes in rock glacier ice well as for their water driven mobilization during accelerated rock glacier degradation. Finally, we argue that monitoring solute fluxes exported from rock glaciers is a promising future research direction for obtaining more reliable estimates of the amount of ice melt exported from rock glaciers.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.

Journal article(s) based on this preprint

14 Nov 2024
Massive mobilization of toxic elements from an intact rock glacier in the central Eastern Alps
Hoda Moradi, Gerhard Furrer, Michael Margreth, David Mair, and Christoph Wanner
The Cryosphere, 18, 5153–5171, https://doi.org/10.5194/tc-18-5153-2024,https://doi.org/10.5194/tc-18-5153-2024, 2024
Short summary
Hoda Moradi, Gerhard Furrer, Michael Margreth, David Mair, and Christoph Wanner

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-789', Stefano Brighenti, 09 May 2024
    • AC1: 'Reply on RC1', Hoda Moradi, 25 Jun 2024
  • RC2: 'Comment on egusphere-2024-789', Anonymous Referee #2, 09 May 2024
    • AC2: 'Reply on RC2', Hoda Moradi, 25 Jun 2024

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-789', Stefano Brighenti, 09 May 2024
    • AC1: 'Reply on RC1', Hoda Moradi, 25 Jun 2024
  • RC2: 'Comment on egusphere-2024-789', Anonymous Referee #2, 09 May 2024
    • AC2: 'Reply on RC2', Hoda Moradi, 25 Jun 2024

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Reconsider after major revisions (further review by editor and referees) (26 Jun 2024) by Caroline Clason
AR by Hoda Moradi on behalf of the Authors (14 Aug 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (22 Aug 2024) by Caroline Clason
RR by Stefano Brighenti (06 Sep 2024)
RR by Anonymous Referee #2 (06 Sep 2024)
ED: Publish subject to minor revisions (review by editor) (06 Sep 2024) by Caroline Clason
AR by Hoda Moradi on behalf of the Authors (16 Sep 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (19 Sep 2024) by Caroline Clason
AR by Hoda Moradi on behalf of the Authors (24 Sep 2024)  Author's response   Manuscript 

Post-review adjustments

AA: Author's adjustment | EA: Editor approval
AA by Hoda Moradi on behalf of the Authors (12 Nov 2024)   Author's adjustment   Manuscript
EA: Adjustments approved (13 Nov 2024) by Caroline Clason

Journal article(s) based on this preprint

14 Nov 2024
Massive mobilization of toxic elements from an intact rock glacier in the central Eastern Alps
Hoda Moradi, Gerhard Furrer, Michael Margreth, David Mair, and Christoph Wanner
The Cryosphere, 18, 5153–5171, https://doi.org/10.5194/tc-18-5153-2024,https://doi.org/10.5194/tc-18-5153-2024, 2024
Short summary
Hoda Moradi, Gerhard Furrer, Michael Margreth, David Mair, and Christoph Wanner

Data sets

Massive mobilization of toxic elements from an intact rock glacier in the Central Eastern Alps: insights into ice melt dynamics Hoda Moradi, Gerhard Furrer, Michael Margreth, David Mair, and Christoph Wanner https://zenodo.org/doi/10.5281/zenodo.10558549

Hoda Moradi, Gerhard Furrer, Michael Margreth, David Mair, and Christoph Wanner

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Short summary
Number of high-altitude streams with high concentrations of toxic elements (Al, F, Mn, Ni) due to pyrite weathering and sulfuric acid production is increasing in the Eastern Alps. In contact of sulfuric acid, these elements are released from rocks and stored in ice in rock glaciers. Today, climate change accelerates rock glacier ice melt which leads to a quick and focused element export in summer. Our research tries to assess consequences of accelerated rock glacier melt on streamwater quality.