Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity
This study provides the first contemporaneous measurements of the concentration and speciation of dissolved nitrogen (N) in snow, meltwater and ice during the onset of the ablation season at a site within the Dark Zone of the Greenland Ice Sheet. The decaying, partially leached snow pack near S6 in...
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Frontiers Media S.A.
2022
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Online Access: | https://doi.org/10.3389/feart.2022.711560 https://doaj.org/article/26a7b372f7e9417c925d6c4ec11c632f |
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ftdoajarticles:oai:doaj.org/article:26a7b372f7e9417c925d6c4ec11c632f 2023-05-15T16:21:18+02:00 Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity Alexandra T. Holland Christopher J. Williamson Andrew J. Tedstone Alexandre M. Anesio Martyn Tranter 2022-03-01T00:00:00Z https://doi.org/10.3389/feart.2022.711560 https://doaj.org/article/26a7b372f7e9417c925d6c4ec11c632f EN eng Frontiers Media S.A. https://www.frontiersin.org/articles/10.3389/feart.2022.711560/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2022.711560 https://doaj.org/article/26a7b372f7e9417c925d6c4ec11c632f Frontiers in Earth Science, Vol 10 (2022) dissolved nitrogen dissolved nutrients spring thaw snow pack Greenland ice sheet nutrient release Science Q article 2022 ftdoajarticles https://doi.org/10.3389/feart.2022.711560 2022-12-31T10:20:13Z This study provides the first contemporaneous measurements of the concentration and speciation of dissolved nitrogen (N) in snow, meltwater and ice during the onset of the ablation season at a site within the Dark Zone of the Greenland Ice Sheet. The decaying, partially leached snow pack near S6 in south-west Greenland produced meltwater with relatively constant nitrate (NO3−) concentrations, approximating the snow pack average (1.1 µM). By contrast, ammonium (NH4+) (0–∼ 4 µM) and dissolved organic nitrogen (DON) (0–∼ 3 µM) concentrations were more variable, and sometimes higher than the average snow pack concentrations of 1.0 and 0.4 µM, respectively. This variability could be the result of microbial uptake and production within the melting snow pack. We observed pooled meltwater at the snow-ice interface that appeared to scavenge DON (∼1–8 µM) and possibly NO3− (∼1–2 µM) from the underlying ice, whose initial surface was a continuum of superimposed ice and weathering crust from the previous season. The shallow meteoric ice (∼10 cm–1 m) beneath the snow pack had high concentrations of DON and NH4+(6.5 and 2.6 µM, respectively), while NO3− concentrations were similar to the snow pack (1.1 µM). The absence of NH4+ in the snowmelt traversing the snow-ice interface may also point to microbial activity occurring at this boundary layer. Melt modelling indicated the presence of liquid meltwater at the snow-ice interface and that at least 10 cm of the surface ice below the snow pack was at 0°C. Solar radiation transmitted through the thin snow pack to the ice surface is absorbed by pigmented glacier algae causing melt of the surrounding ice, allowing the possibly of photosynthesis to begin under the thinning snowpack in these micro-melt environments. Hence, we conjecture that glacier algal blooms can commence before the snow pack has completely melted, occuring at a time when meltwaters are enhanced in nutrients scavenged from the snowpack, superimposed ice and the remnants of the weathering crust from the previous ... Article in Journal/Newspaper glacier Greenland Ice Sheet Directory of Open Access Journals: DOAJ Articles Greenland Frontiers in Earth Science 10 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
dissolved nitrogen dissolved nutrients spring thaw snow pack Greenland ice sheet nutrient release Science Q |
spellingShingle |
dissolved nitrogen dissolved nutrients spring thaw snow pack Greenland ice sheet nutrient release Science Q Alexandra T. Holland Christopher J. Williamson Andrew J. Tedstone Alexandre M. Anesio Martyn Tranter Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity |
topic_facet |
dissolved nitrogen dissolved nutrients spring thaw snow pack Greenland ice sheet nutrient release Science Q |
description |
This study provides the first contemporaneous measurements of the concentration and speciation of dissolved nitrogen (N) in snow, meltwater and ice during the onset of the ablation season at a site within the Dark Zone of the Greenland Ice Sheet. The decaying, partially leached snow pack near S6 in south-west Greenland produced meltwater with relatively constant nitrate (NO3−) concentrations, approximating the snow pack average (1.1 µM). By contrast, ammonium (NH4+) (0–∼ 4 µM) and dissolved organic nitrogen (DON) (0–∼ 3 µM) concentrations were more variable, and sometimes higher than the average snow pack concentrations of 1.0 and 0.4 µM, respectively. This variability could be the result of microbial uptake and production within the melting snow pack. We observed pooled meltwater at the snow-ice interface that appeared to scavenge DON (∼1–8 µM) and possibly NO3− (∼1–2 µM) from the underlying ice, whose initial surface was a continuum of superimposed ice and weathering crust from the previous season. The shallow meteoric ice (∼10 cm–1 m) beneath the snow pack had high concentrations of DON and NH4+(6.5 and 2.6 µM, respectively), while NO3− concentrations were similar to the snow pack (1.1 µM). The absence of NH4+ in the snowmelt traversing the snow-ice interface may also point to microbial activity occurring at this boundary layer. Melt modelling indicated the presence of liquid meltwater at the snow-ice interface and that at least 10 cm of the surface ice below the snow pack was at 0°C. Solar radiation transmitted through the thin snow pack to the ice surface is absorbed by pigmented glacier algae causing melt of the surrounding ice, allowing the possibly of photosynthesis to begin under the thinning snowpack in these micro-melt environments. Hence, we conjecture that glacier algal blooms can commence before the snow pack has completely melted, occuring at a time when meltwaters are enhanced in nutrients scavenged from the snowpack, superimposed ice and the remnants of the weathering crust from the previous ... |
format |
Article in Journal/Newspaper |
author |
Alexandra T. Holland Christopher J. Williamson Andrew J. Tedstone Alexandre M. Anesio Martyn Tranter |
author_facet |
Alexandra T. Holland Christopher J. Williamson Andrew J. Tedstone Alexandre M. Anesio Martyn Tranter |
author_sort |
Alexandra T. Holland |
title |
Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity |
title_short |
Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity |
title_full |
Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity |
title_fullStr |
Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity |
title_full_unstemmed |
Dissolved Nitrogen Speciation and Concentration During Spring Thaw in the Greenland Ice Sheet Dark Zone: Evidence for Microbial Activity |
title_sort |
dissolved nitrogen speciation and concentration during spring thaw in the greenland ice sheet dark zone: evidence for microbial activity |
publisher |
Frontiers Media S.A. |
publishDate |
2022 |
url |
https://doi.org/10.3389/feart.2022.711560 https://doaj.org/article/26a7b372f7e9417c925d6c4ec11c632f |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
glacier Greenland Ice Sheet |
genre_facet |
glacier Greenland Ice Sheet |
op_source |
Frontiers in Earth Science, Vol 10 (2022) |
op_relation |
https://www.frontiersin.org/articles/10.3389/feart.2022.711560/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2022.711560 https://doaj.org/article/26a7b372f7e9417c925d6c4ec11c632f |
op_doi |
https://doi.org/10.3389/feart.2022.711560 |
container_title |
Frontiers in Earth Science |
container_volume |
10 |
_version_ |
1766009308299919360 |