Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing
Climate-driven changes in Arctic hydrology and biogeochemistry are impacting transport of water and water-borne material from land to ocean. This includes massive amounts of organic matter that are mobilized and exported from the pan-Arctic watershed via rivers each year. Dissolved organic matter (D...
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ftunivtexas:oai:repositories.lib.utexas.edu:2152/40312 2023-05-15T14:36:25+02:00 Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing Griffin, Claire Genevieve McClelland, James W. Frey, Karen E Gardner, Wayne S Liu, Zhanfei Shank, Gerald C 2016-05 application/pdf http://hdl.handle.net/2152/40312 https://doi.org/10.15781/T28K74X4R unknown doi:10.15781/T28K74X4R http://hdl.handle.net/2152/40312 Arctic Dissolved organic matter Climate change Remote sensing Carbon cycle Rivers Thesis text 2016 ftunivtexas https://doi.org/10.15781/T28K74X4R 2020-12-23T22:06:01Z Climate-driven changes in Arctic hydrology and biogeochemistry are impacting transport of water and water-borne material from land to ocean. This includes massive amounts of organic matter that are mobilized and exported from the pan-Arctic watershed via rivers each year. Dissolved organic matter (DOM), an important part of the Arctic carbon cycle, has received growing attention in recent years, yet long-term studies of riverine biogeochemistry remain rare in these remote and logistically challenging regions. Remote sensing of chromophoric dissolved organic matter (CDOM, the portion of the DOM pool that absorbs light), provides a unique opportunity to investigate variations in DOM in major Arctic rivers over multiple decades. CDOM is a useful proxy for dissolved organic carbon (DOC) and is essential to photochemical processes in surface waters. This dissertation presents the development and application of remote sensing regression models across six major Arctic rivers: the Kolyma, Lena, Mackenzie, Ob', Yenisey and Yukon. Frozen, archival samples of CDOM were used to develop calibration data for remote sensing regressions. Remote sensing methods estimated CDOM with R² of 85% across all rivers, although individual rivers varied in their predictability in association with sediment loading and hydrology. As with previous studies of Arctic systems, concentrations and export of CDOM and DOC were highest during spring freshet in most of these rivers. Interannual variability in DOM export may be linked to the Arctic Oscillation. Within the Mackenzie, Ob', and Yenisey rivers, observations of DOM concentration and export were extended back to the 1980s, the first known empirical records of this length for Arctic rivers that span both continents. Although no pan-Arctic trends in CDOM export were detected, there is some evidence of long-term changes in riverine DOM. For example, discharge-specific CDOM concentrations decreased in the Yenisey River and increased in the Ob' River. Additionally, CDOM concentrations increased over the past ~30 years within the Mackenzie River. This dissertation also includes results from experiments used to quantify the effects of cryopreservation on CDOM analyses, and potential approaches for ameliorating freezing effects. These experiments showed that freezing for preservation introduces some error into CDOM measurements, although these effects vary between river systems. Sonication may improve CDOM measurements in some river systems, but the effects of both cryopreservation and sonication should be quantified on a case-by-case basis. Overall, this dissertation work demonstrates that 1) remote sensing of CDOM is a viable tool for tracking fluvial DOM in the major Arctic rivers, 2) only the Mackenzie River showed significant increases in CDOM concentration from the 1980s to present and 3) long-term changes in discharge-specific CDOM concentrations have occurred in the Yenisey and Ob' rivers. These long-term trends cannot be definitively linked to climate change, but may be related to effects of warming on permafrost, hydrology, and biogeochemistry within in Arctic watersheds with consequences for carbon cycling on both regional and global scales. Marine Science Thesis Arctic Climate change Mackenzie river ob river permafrost yenisey river Yukon The University of Texas at Austin: Texas ScholarWorks Arctic Yukon Mackenzie River Kolyma ENVELOPE(161.000,161.000,69.500,69.500) Yenisey ENVELOPE(82.680,82.680,71.828,71.828) |
institution |
Open Polar |
collection |
The University of Texas at Austin: Texas ScholarWorks |
op_collection_id |
ftunivtexas |
language |
unknown |
topic |
Arctic Dissolved organic matter Climate change Remote sensing Carbon cycle Rivers |
spellingShingle |
Arctic Dissolved organic matter Climate change Remote sensing Carbon cycle Rivers Griffin, Claire Genevieve Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing |
topic_facet |
Arctic Dissolved organic matter Climate change Remote sensing Carbon cycle Rivers |
description |
Climate-driven changes in Arctic hydrology and biogeochemistry are impacting transport of water and water-borne material from land to ocean. This includes massive amounts of organic matter that are mobilized and exported from the pan-Arctic watershed via rivers each year. Dissolved organic matter (DOM), an important part of the Arctic carbon cycle, has received growing attention in recent years, yet long-term studies of riverine biogeochemistry remain rare in these remote and logistically challenging regions. Remote sensing of chromophoric dissolved organic matter (CDOM, the portion of the DOM pool that absorbs light), provides a unique opportunity to investigate variations in DOM in major Arctic rivers over multiple decades. CDOM is a useful proxy for dissolved organic carbon (DOC) and is essential to photochemical processes in surface waters. This dissertation presents the development and application of remote sensing regression models across six major Arctic rivers: the Kolyma, Lena, Mackenzie, Ob', Yenisey and Yukon. Frozen, archival samples of CDOM were used to develop calibration data for remote sensing regressions. Remote sensing methods estimated CDOM with R² of 85% across all rivers, although individual rivers varied in their predictability in association with sediment loading and hydrology. As with previous studies of Arctic systems, concentrations and export of CDOM and DOC were highest during spring freshet in most of these rivers. Interannual variability in DOM export may be linked to the Arctic Oscillation. Within the Mackenzie, Ob', and Yenisey rivers, observations of DOM concentration and export were extended back to the 1980s, the first known empirical records of this length for Arctic rivers that span both continents. Although no pan-Arctic trends in CDOM export were detected, there is some evidence of long-term changes in riverine DOM. For example, discharge-specific CDOM concentrations decreased in the Yenisey River and increased in the Ob' River. Additionally, CDOM concentrations increased over the past ~30 years within the Mackenzie River. This dissertation also includes results from experiments used to quantify the effects of cryopreservation on CDOM analyses, and potential approaches for ameliorating freezing effects. These experiments showed that freezing for preservation introduces some error into CDOM measurements, although these effects vary between river systems. Sonication may improve CDOM measurements in some river systems, but the effects of both cryopreservation and sonication should be quantified on a case-by-case basis. Overall, this dissertation work demonstrates that 1) remote sensing of CDOM is a viable tool for tracking fluvial DOM in the major Arctic rivers, 2) only the Mackenzie River showed significant increases in CDOM concentration from the 1980s to present and 3) long-term changes in discharge-specific CDOM concentrations have occurred in the Yenisey and Ob' rivers. These long-term trends cannot be definitively linked to climate change, but may be related to effects of warming on permafrost, hydrology, and biogeochemistry within in Arctic watersheds with consequences for carbon cycling on both regional and global scales. Marine Science |
author2 |
McClelland, James W. Frey, Karen E Gardner, Wayne S Liu, Zhanfei Shank, Gerald C |
format |
Thesis |
author |
Griffin, Claire Genevieve |
author_facet |
Griffin, Claire Genevieve |
author_sort |
Griffin, Claire Genevieve |
title |
Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing |
title_short |
Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing |
title_full |
Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing |
title_fullStr |
Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing |
title_full_unstemmed |
Dissolved organic matter in major rivers across the Pan-Arctic from remote sensing |
title_sort |
dissolved organic matter in major rivers across the pan-arctic from remote sensing |
publishDate |
2016 |
url |
http://hdl.handle.net/2152/40312 https://doi.org/10.15781/T28K74X4R |
long_lat |
ENVELOPE(161.000,161.000,69.500,69.500) ENVELOPE(82.680,82.680,71.828,71.828) |
geographic |
Arctic Yukon Mackenzie River Kolyma Yenisey |
geographic_facet |
Arctic Yukon Mackenzie River Kolyma Yenisey |
genre |
Arctic Climate change Mackenzie river ob river permafrost yenisey river Yukon |
genre_facet |
Arctic Climate change Mackenzie river ob river permafrost yenisey river Yukon |
op_relation |
doi:10.15781/T28K74X4R http://hdl.handle.net/2152/40312 |
op_doi |
https://doi.org/10.15781/T28K74X4R |
_version_ |
1766309037289242624 |