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Permanent link (DOI): https://doi.org/10.7939/R3KD1R04P

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Records of atmospheric mercury deposition and post-depositional mobility in peat permafrost archives from central and northern Yukon, Canada Open Access

Descriptions

Other title
Subject/Keyword
Klondike
Biogeochemistry
Holocene
Peat
Mercury
Bulk density
Methylmercury
Homogenization
Deposition flux
Permafrost
Yukon
Anthropogenic
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Bandara, Sasiri
Supervisor and department
Froese, Duane (Earth and Atmospheric Sciences)
St. Louis, Vincent (Biological Sciences)
Examining committee member and department
Cooke, Colin (Earth and Atmospheric Sciences)
Reyes, Alberto (Earth and Atmospheric Sciences)
Department
Department of Earth and Atmospheric Sciences
Specialization

Date accepted
2017-09-28T15:29:23Z
Graduation date
2017-11:Fall 2017
Degree
Master of Science
Degree level
Master's
Abstract
Environmental archives provide a feasible means for studying the biogeochemical cycling of heavy metals including mercury (Hg). Although many temperate peat bogs have been successfully used to reconstruct natural and anthropogenic atmospheric Hg deposition fluxes, northern circumpolar permafrost peatlands are largely understudied in similar research. Consequently, substantial gaps remain in our understanding of past atmospheric Hg deposition fluxes and present peatland Hg inventories from northern environments. This thesis presents a critical investigation of using peat permafrost archives for quantifying natural and anthropogenic atmospheric Hg deposition fluxes. The first objective of this research was to develop an effective protocol for collecting and processing peat permafrost samples for inorganic geochemical analyses. Refined techniques were established for accurately measuring bulk density and homogenizing well-preserved fibrous peat. This method was then used to reconstruct historic atmospheric Hg deposition from a permafrost peat plateau near Dawson, Yukon, with the aim of resolving a deposition peak corresponding to extensive Klondike gold mining during the late 19th and early 20th centuries. The results revealed an unexpectedly early increase in anthropogenic Hg deposition, which was ultimately interpreted to result from post-depositional Hg mobility within the seasonally thawed active layer. This discovery implies that peat permafrost archives may not provide reliable high-resolution records of atmospheric Hg deposition. However, a subsequent study involving seven Holocene (10,000-year old) peat plateaus from central and northern Yukon reveal that millennial-scale atmospherically deposited Hg concentrations and fluxes were consistently low; ~20.7 ± 9.8 ngg-1 and ~0.51 ± 0.39 μgm-2y-1, respectively. These results were used to demonstrate how peat permafrost Hg inventories could be estimated at the local scale. Provided additional empirical data from sites spanning the northern circumpolar region, future studies may use the same approach to estimate cryosol Hg stocks at regional to global scales and assess the potential vulnerability of Hg release from thawing permafrost with continued climate warming.
Language
English
DOI
doi:10.7939/R3KD1R04P
Rights
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
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