COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE
Arctic ecosystems are a major global sink for both carbon (C) and mercury (Hg), both of which are influenced by anthropogenic activities. The accelerated climate-change-induced warming documented in the Arctic has led to permafrost thaw resulting in landscape evolution from hydrological, vegetation...
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ftuninhampshire:oai:scholars.unh.edu:dissertation-3668 2023-05-15T12:59:50+02:00 COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE Fahnestock, Maria F 2022-05-01T07:00:00Z application/pdf https://scholars.unh.edu/dissertation/2669 https://scholars.unh.edu/cgi/viewcontent.cgi?article=3668&context=dissertation unknown University of New Hampshire Scholars' Repository https://scholars.unh.edu/dissertation/2669 https://scholars.unh.edu/cgi/viewcontent.cgi?article=3668&context=dissertation Doctoral Dissertations Arctic climate change mercury permafrost text 2022 ftuninhampshire 2023-01-30T22:45:18Z Arctic ecosystems are a major global sink for both carbon (C) and mercury (Hg), both of which are influenced by anthropogenic activities. The accelerated climate-change-induced warming documented in the Arctic has led to permafrost thaw resulting in landscape evolution from hydrological, vegetation and microbial shifts. All of these resulting changes have the potential to influence how Hg, a toxic contaminant, is mobilized and re-cycled in this ecosystem. In this body of work, I investigate patterns of Hg speciation, elemental abundances, and stable isotopes across the thaw gradient in a permafrost peatland and interconnected freshwater lakes in Abisko, Sweden to assess changes in Hg storage and in Hg export pathways. In Chapter 2 (republished from Fahnestock et al., 2019), I report results suggest that during initial stages of permafrost thaw, when the active layer in the palsa deepens, export of gas-phase mercury may be an important pathway of Hg loss. As the thaw continues vegetation changes to a Sphagnum-dominated semi-thawed ecosystem, where Hg export into the atmosphere limits accumulation of Hg in peat and the peat bound HgT pool is depleted. In the final stage of thaw, characterized by fully thawed fens, more labile organic matter and a diverse microbial community result in greater Hg retention in fen peat and higher levels of porewater MeHg that may be exported to nearby lakes and streams. Hg stable isotopes employed in Chapter 3 provide evidence supporting the importance of vegetation as an important sink of Hg in Arctic peatlands, show that photoreduction processes are important across the landscape and that ombrotrophic bogs may retain more Hg from wet deposition. Taken together, these findings suggest that Hg cycling in thawing peatlands will be influenced by future climatological patterns that drive the hydrological conditions, particularly the hydrologic connectivity, of this ecosystem. Chapters 4 and 5 consider the role of Arctic lakes in an ecosystem undergoing permafrost thaw. In Chapter 4, ... Text Abisko Arctic Climate change palsa permafrost University of New Hampshire: Scholars Repository Arctic Abisko ENVELOPE(18.829,18.829,68.349,68.349) |
institution |
Open Polar |
collection |
University of New Hampshire: Scholars Repository |
op_collection_id |
ftuninhampshire |
language |
unknown |
topic |
Arctic climate change mercury permafrost |
spellingShingle |
Arctic climate change mercury permafrost Fahnestock, Maria F COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE |
topic_facet |
Arctic climate change mercury permafrost |
description |
Arctic ecosystems are a major global sink for both carbon (C) and mercury (Hg), both of which are influenced by anthropogenic activities. The accelerated climate-change-induced warming documented in the Arctic has led to permafrost thaw resulting in landscape evolution from hydrological, vegetation and microbial shifts. All of these resulting changes have the potential to influence how Hg, a toxic contaminant, is mobilized and re-cycled in this ecosystem. In this body of work, I investigate patterns of Hg speciation, elemental abundances, and stable isotopes across the thaw gradient in a permafrost peatland and interconnected freshwater lakes in Abisko, Sweden to assess changes in Hg storage and in Hg export pathways. In Chapter 2 (republished from Fahnestock et al., 2019), I report results suggest that during initial stages of permafrost thaw, when the active layer in the palsa deepens, export of gas-phase mercury may be an important pathway of Hg loss. As the thaw continues vegetation changes to a Sphagnum-dominated semi-thawed ecosystem, where Hg export into the atmosphere limits accumulation of Hg in peat and the peat bound HgT pool is depleted. In the final stage of thaw, characterized by fully thawed fens, more labile organic matter and a diverse microbial community result in greater Hg retention in fen peat and higher levels of porewater MeHg that may be exported to nearby lakes and streams. Hg stable isotopes employed in Chapter 3 provide evidence supporting the importance of vegetation as an important sink of Hg in Arctic peatlands, show that photoreduction processes are important across the landscape and that ombrotrophic bogs may retain more Hg from wet deposition. Taken together, these findings suggest that Hg cycling in thawing peatlands will be influenced by future climatological patterns that drive the hydrological conditions, particularly the hydrologic connectivity, of this ecosystem. Chapters 4 and 5 consider the role of Arctic lakes in an ecosystem undergoing permafrost thaw. In Chapter 4, ... |
format |
Text |
author |
Fahnestock, Maria F |
author_facet |
Fahnestock, Maria F |
author_sort |
Fahnestock, Maria F |
title |
COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE |
title_short |
COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE |
title_full |
COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE |
title_fullStr |
COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE |
title_full_unstemmed |
COMPOUND, ELEMENTAL, AND ISOTOPIC PERSPECTIVES ON MERCURY MOBILIZATION DURING THAW IN A DISCONTINUOUS PERMAFROST ZONE |
title_sort |
compound, elemental, and isotopic perspectives on mercury mobilization during thaw in a discontinuous permafrost zone |
publisher |
University of New Hampshire Scholars' Repository |
publishDate |
2022 |
url |
https://scholars.unh.edu/dissertation/2669 https://scholars.unh.edu/cgi/viewcontent.cgi?article=3668&context=dissertation |
long_lat |
ENVELOPE(18.829,18.829,68.349,68.349) |
geographic |
Arctic Abisko |
geographic_facet |
Arctic Abisko |
genre |
Abisko Arctic Climate change palsa permafrost |
genre_facet |
Abisko Arctic Climate change palsa permafrost |
op_source |
Doctoral Dissertations |
op_relation |
https://scholars.unh.edu/dissertation/2669 https://scholars.unh.edu/cgi/viewcontent.cgi?article=3668&context=dissertation |
_version_ |
1766114742079848448 |