Meltwater runoff from the Greenland Ice Sheet reveals microbial consortia from contrasting subglacial drainage systems

Lamarche-Gagnon, Guillaume; Anesio, Alexandre M.; Wadham, Jemma L.; Žárský, Jakub D.; Kohler, Tyler J.; Bagshaw, Elizabeth; Telling, Jon; Hawkings, Jon R.; Stibal, Marek

doi:10.1101/2020.05.26.116566

Cited by 2 publications

(1 citation statement)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A full description of microbiological sample collection and DNA extraction can be found in refs. 22,70 , as the extracts sequenced for metagenomes here consisted of subsamples of those used for 16S rRNA gene analysis in the cited studies.…”

Section: Microbiological Analysis (2015)mentioning

confidence: 99%

Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

et al. 2021

Self Cite

View full text Add to dashboard Cite

The Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. We show that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments (521–3,300 mmol km−2 year−1) are two orders of magnitude higher than from Arctic rivers (4–20 mmol km−2 year−1). Fluxes of dissolved mercury from the southwestern region of Greenland are estimated to be globally significant (15.4–212 kmol year−1), accounting for about 10% of the estimated global riverine flux, and include export of bioaccumulating methylmercury (0.31–1.97 kmol year−1). High dissolved mercury concentrations (~20 pM inorganic mercury and ~2 pM methylmercury) were found to persist across salinity gradients of fjords. Mean particulate mercury concentrations were among the highest recorded in the literature (~51,000 pM), and dissolved mercury concentrations in runoff exceed reported surface snow and ice values. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting an urgent need to better understand mercury dynamics in ice sheet runoff under global warming.

show abstract

Section: Microbiological Analysis (2015)mentioning

confidence: 99%

Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

Geological and glacial-hydrologic controls on chemical weathering in the subglacial environment

Graly

Rezvanbehbahani

2022

Ann. Glaciol.

View full text Add to dashboard Cite

A comparison of major ion chemistry of subglacial boreholes and discharging subglacial waters reveals three fundamentally different glacier hydrochemical regimes. Subglacial waters from alpine glaciers have chemistry distinct from the subglacial waters of Greenland or Antarctica. Greenland and Antarctica also differ fundamentally from each other, with Greenland Ice Sheet waters, at least during the summer melt season, remaining dilute and unaffected by saturation reactions and Antarctic Ice Sheet waters controlled by a range of saturation states. Some Antarctic waters form concentrated brines, capable of depressing the freezing point by >10°C. While these waters have only been directly sampled where they rarely emerge, geophysical observations from Devon Ice Cap and Greenland show liquid water at the glacier bed in locations where ice is thin and slowly moving and a cold bed is otherwise expected. This raises the possibility that lithogenic subglacial brines could be widespread and that our existing subglacial hydrochemical measurements might be biased by seasonal sampling of freely discharging water. The potential for diverse ranges of subglacial environments under ice sheets suggests the need for new and ambitious sampling programs to characterize difficult to access subglacial waters and quantify their impact on glacier dynamics, geobiology and global geochemical cycling.

show abstract

Meltwater runoff from the Greenland Ice Sheet reveals microbial consortia from contrasting subglacial drainage systems

Abstract: 18

Cited by 2 publications

References 60 publications

Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

Geological and glacial-hydrologic controls on chemical weathering in the subglacial environment

Contact Info

Product

Resources

About