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Neglected fluxes: Understanding the evolution of weathering as continental ice sheets retreat

General

Organisation
Project start
01.01.2016
Project end
31.12.2019
Type of project
ARMAP/NSF
Project theme
Geoscience
Project topic
Geology

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 67.0179977417, -50.69400024414

Fieldwork start
17.08.2017
Fieldwork end
19.09.2017

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 61.1605, -45.426

Fieldwork start
31.08.2017
Fieldwork end
12.09.2017

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 61.238333, -45.398889

Fieldwork start
01.09.2017
Fieldwork end
09.09.2017

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 66.93, -53.68

Fieldwork start
20.08.2017
Fieldwork end
29.08.2017

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 67.0179977417, -50.69400024414

Fieldwork start
07.08.2018
Fieldwork end
15.08.2018

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 61.1605, -45.426

Fieldwork start
27.07.2018
Fieldwork end
07.08.2018

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 64.1833, -51.75

Fieldwork start
24.07.2018
Fieldwork end
27.07.2018

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 61.238333, -45.398889

Fieldwork start
27.07.2018
Fieldwork end
07.08.2018

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 66.93, -53.68

Fieldwork start
02.07.2018
Fieldwork end
13.07.2018

SAR information

Project details

14.11.2018
Science / project summary

The Greenland Ice Sheet is the largest remaining continental ice sheet in the northern hemisphere. Past and future arctic warming leads to ice sheet retreat and alters the fundamental nature of weathering and the delivery of nutrients and elements to the ocean. The proposed work is focused on the hydrological, biological, biogeochemical, and isotopic signatures of proglacial watersheds, which are watershed that convey dilute but high volume glacial meltwater from the top and underneath the ice sheet to the ocean, and deglaciated watersheds, which are watersheds that are no longer physically connected to the ice sheet and sourced only by annual precipitation and permafrost melt. Although deglaciated watersheds have received less attention, preliminary work suggests they may be equally or more important than proglacial watersheds for oceanic and atmospheric fluxes. Moreover, as ice sheets melt, the area contributing to meltwater and constituent fluxes will increasingly be from deglaciated watersheds. The understanding gained from this work will provide a context for the prediction of future land-ocean and land-atmosphere fluxes in response to continued ice sheet retreat. This project therefore addresses the question of how mineral weathering reactions impact atmospheric CO2 and oceanic nutrient and isotope delivery across proglacial and deglacial watersheds in three environmentally distinct regions of Greenland. Results of the project have the potential to change our understanding of global CO2, nutrient, and isotope cycling in response to ice sheet collapse and permit predictions of future responses to global warming and ice sheet retreat. Results will also provide a context to interpret past high latitude ice sheet retreat and climate change based on marine isotope records. The project includes training for undergraduate, graduate, and postdoctoral researchers, as well as a collaboration with students and faculty at a Greenlandic academic institution. This study will test the hypotheses that (1) deglacial and proglacial watersheds contribute distinct elemental, isotopic, and nutrient fluxes to the ocean and atmosphere as a result of evolving weathering patterns, and (2) these reactions and associated fluxes will change within and between watersheds as the Greenland Ice Sheet retreats. The project focuses on three field areas: deglacial and proglacial watersheds near Kangerlussuaq and Narsasuaq and a deglacial watershed near Sisimiut. Each area has a distinct water balance, exposure age, and weathering characteristics, and will be sampled three times over two melt seasons to evaluate intra-seasonal and inter-annual variations. Mass balance models and PHREEQc modeling of solute data will be used to identify and assess extents of weathering reactions. Weathering extents will also be estimated based on trends in proportional contributions of minerals and offsets between dissolved and bedload strontium and lead isotope ratios, and will be linked to phosphorous fluxes and organic carbon lability and degradation. This holistic approach will provide a broad view of the relative elemental, nutrient and isotopic fluxes in proglacial and deglacial environments. These results will provide magnitudes, time scales, and drivers of weathering reactions, with a goal of linking fluxes to past records and future predictions of global climate change associated with continental ice sheet collapse.

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