GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES
Retreat of continental ice sheets exposed ~15% of Earth’s land surface from the Last Glacial Maximum (LGM) to about 6 ka and recent warming has increased glacial melting and meltwater solute fluxes to the oceans. Additional solutes originate from non-glacial streams in landscapes exposed since the L...
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ftuninebromaha:oai:digitalcommons.unomaha.edu:geoggeolfacproc-1004 2024-02-11T10:04:20+01:00 GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES Martin, Jonathan Pain, Andrea Martin, Ellen Black, Megan Deuerling, Kelly M. 2021-10-12T07:00:00Z https://digitalcommons.unomaha.edu/geoggeolfacproc/12 https://gsa.confex.com/gsa/2021AM/videogateway.cgi/id/4465?recordingid=4465 https://digitalcommons.unomaha.edu/context/geoggeolfacproc/article/1004/filename/0/type/additional/viewcontent/GREENLAND_REVISITED__LAKE_EFFECTS_ON_COASTAL_NUTRIENT_FLUXES__GSA_Connects_2021_in_Portland__Oregon_.pdf unknown DigitalCommons@UNO https://digitalcommons.unomaha.edu/geoggeolfacproc/12 https://gsa.confex.com/gsa/2021AM/videogateway.cgi/id/4465?recordingid=4465 https://digitalcommons.unomaha.edu/context/geoggeolfacproc/article/1004/filename/0/type/additional/viewcontent/GREENLAND_REVISITED__LAKE_EFFECTS_ON_COASTAL_NUTRIENT_FLUXES__GSA_Connects_2021_in_Portland__Oregon_.pdf Geography and Geology Faculty Proceedings & Presentations text 2021 ftuninebromaha 2024-01-14T17:40:48Z Retreat of continental ice sheets exposed ~15% of Earth’s land surface from the Last Glacial Maximum (LGM) to about 6 ka and recent warming has increased glacial melting and meltwater solute fluxes to the oceans. Additional solutes originate from non-glacial streams in landscapes exposed since the LGM. As presented in last year’s pandemic-modified Birdsall-Dreiss lecture, Greenlandic glacial and non-glacial streams have distinct solute concentrations because of differing chemical weathering regimes of comminuted glacial sediment. In this year’s lecture, we evaluate an ~46 km2 non-glacial watershed near Sisimiut, Greenland to assess how lakes may impact non-glacial solute fluxes. Snow accumulates in the watershed from October to freshet in early May, after which discharge responds solely to precipitation events. Three main tributaries provide 92% of flow to the outlet stream and drain sub-watersheds with median slope angles of 16 to 18% and small upland lakes that cover 0.5 and 3.8% of the land area. In contrast, the outlet stream discharges from a landscape with a median slope of ~6% that includes one large and one small lake covering 23% of the area. Streams above and below the outlet lakes show similar variations in solute concentrations through the melt season. However, soon after freshet the outlet stream has major element concentrations ~20% greater than in the tributaries. The excess solute concentrations decrease linearly for ~90 days at which time the tributaries and outlet have similar concentrations. The excess solutes at the outlet may result from over-winter mineral dissolution in lake sediments, cryogenic solute enrichment during lake freeze-in, or dilute runoff in tributaries from snowmelt during and soon after freshet. In contrast, the outlet stream has a 0.6 to 3 times deficit of PO4, NO3, and Si compared with the tributaries, suggesting assimilation within the lake. NH4 concentrations switch from ~60% deficit to ~ 60% excess, reflecting a switch from a lake sink to source. The differences ... Text Greenland greenlandic Sisimiut University of Nebraska Omaha: DigitalCommons@UNO Greenland Sisimiut ENVELOPE(-53.674,-53.674,66.939,66.939) Birdsall ENVELOPE(-81.800,-81.800,50.917,50.917) |
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Open Polar |
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University of Nebraska Omaha: DigitalCommons@UNO |
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ftuninebromaha |
language |
unknown |
description |
Retreat of continental ice sheets exposed ~15% of Earth’s land surface from the Last Glacial Maximum (LGM) to about 6 ka and recent warming has increased glacial melting and meltwater solute fluxes to the oceans. Additional solutes originate from non-glacial streams in landscapes exposed since the LGM. As presented in last year’s pandemic-modified Birdsall-Dreiss lecture, Greenlandic glacial and non-glacial streams have distinct solute concentrations because of differing chemical weathering regimes of comminuted glacial sediment. In this year’s lecture, we evaluate an ~46 km2 non-glacial watershed near Sisimiut, Greenland to assess how lakes may impact non-glacial solute fluxes. Snow accumulates in the watershed from October to freshet in early May, after which discharge responds solely to precipitation events. Three main tributaries provide 92% of flow to the outlet stream and drain sub-watersheds with median slope angles of 16 to 18% and small upland lakes that cover 0.5 and 3.8% of the land area. In contrast, the outlet stream discharges from a landscape with a median slope of ~6% that includes one large and one small lake covering 23% of the area. Streams above and below the outlet lakes show similar variations in solute concentrations through the melt season. However, soon after freshet the outlet stream has major element concentrations ~20% greater than in the tributaries. The excess solute concentrations decrease linearly for ~90 days at which time the tributaries and outlet have similar concentrations. The excess solutes at the outlet may result from over-winter mineral dissolution in lake sediments, cryogenic solute enrichment during lake freeze-in, or dilute runoff in tributaries from snowmelt during and soon after freshet. In contrast, the outlet stream has a 0.6 to 3 times deficit of PO4, NO3, and Si compared with the tributaries, suggesting assimilation within the lake. NH4 concentrations switch from ~60% deficit to ~ 60% excess, reflecting a switch from a lake sink to source. The differences ... |
format |
Text |
author |
Martin, Jonathan Pain, Andrea Martin, Ellen Black, Megan Deuerling, Kelly M. |
spellingShingle |
Martin, Jonathan Pain, Andrea Martin, Ellen Black, Megan Deuerling, Kelly M. GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES |
author_facet |
Martin, Jonathan Pain, Andrea Martin, Ellen Black, Megan Deuerling, Kelly M. |
author_sort |
Martin, Jonathan |
title |
GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES |
title_short |
GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES |
title_full |
GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES |
title_fullStr |
GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES |
title_full_unstemmed |
GREENLAND REVISITED: LAKE EFFECTS ON COASTAL NUTRIENT FLUXES |
title_sort |
greenland revisited: lake effects on coastal nutrient fluxes |
publisher |
DigitalCommons@UNO |
publishDate |
2021 |
url |
https://digitalcommons.unomaha.edu/geoggeolfacproc/12 https://gsa.confex.com/gsa/2021AM/videogateway.cgi/id/4465?recordingid=4465 https://digitalcommons.unomaha.edu/context/geoggeolfacproc/article/1004/filename/0/type/additional/viewcontent/GREENLAND_REVISITED__LAKE_EFFECTS_ON_COASTAL_NUTRIENT_FLUXES__GSA_Connects_2021_in_Portland__Oregon_.pdf |
long_lat |
ENVELOPE(-53.674,-53.674,66.939,66.939) ENVELOPE(-81.800,-81.800,50.917,50.917) |
geographic |
Greenland Sisimiut Birdsall |
geographic_facet |
Greenland Sisimiut Birdsall |
genre |
Greenland greenlandic Sisimiut |
genre_facet |
Greenland greenlandic Sisimiut |
op_source |
Geography and Geology Faculty Proceedings & Presentations |
op_relation |
https://digitalcommons.unomaha.edu/geoggeolfacproc/12 https://gsa.confex.com/gsa/2021AM/videogateway.cgi/id/4465?recordingid=4465 https://digitalcommons.unomaha.edu/context/geoggeolfacproc/article/1004/filename/0/type/additional/viewcontent/GREENLAND_REVISITED__LAKE_EFFECTS_ON_COASTAL_NUTRIENT_FLUXES__GSA_Connects_2021_in_Portland__Oregon_.pdf |
_version_ |
1790600919471095808 |