Tags: physical sciences, mercury, permafrost, climate change
| Principal Investigator: | Porter, Trevor (5) |
| Licence Number: | 16146 |
| Organization: | University of Toronto |
| Licensed Year(s): |
2017
|
| Issued: | Jul 20, 2017 |
| Project Team: | Trevor Porter, Kira Holland, Steven Kokelj |
Objective(s): To better understand long-term changes in winter temperatures and atmospheric mercury (Hg) in the Mackenzie Delta area over the last 11,700 years.
Project Description: This purpose of this research is to better understand long-term changes in winter temperatures and atmospheric mercury (Hg) in the Mackenzie Delta area over the last 11,700 years, a period known as the Holocene. The fieldwork aims to sample 20-30 ice wedges that represent a range of Holocene time. Precipitation stable hydrogen isotopes (a temperature proxy) and elemental Hg archived in the wedge ice veins will be measured and used to reconstruct changes in climate and Hg. These data will provide insights that will lead to improved understandings of Arctic climate dynamics and Hg cycling, and their relationship. Ice veins within an ice wedge represent discrete growth phases of an ice wedge body, and in certain conditions can document thousands of years. Wedge ice is a blend of winter precipitation delivered as snowmelt to thermal contraction crack in the ground, and which has been preserved as relict ice below the permafrost table. Similar to ice-cores, the stable hydrogen isotope ratios of wedge ice can be used as a reliable indicator of past temperature. Furthermore, concentrations of mercury (Hg) within ice veins can be used to reconstruct past changes in atmospheric Hg. Active and relict ice wedge sites in the Mackenzie Delta study area will be targeted, especially lateral exposures created by thaw slumps and river cuts which provide the opportunity to sample individual ice veins across an ice wedge, representing different years of growth. A gas-powered drill or chain saw will be used to sub-sample the wedges. Plant material within ice veins will be radiocarbon dated, and used to estimate the age of the ice veins. Wedge ice samples will be thawed, filtered and analysed for stable hydrogen isotope ratios at the University of Alberta. Finally, the same samples will be analysed for Hg content using a Tekran Mercury Analyser at the University of Toronto Mississauga. Field and laboratory work will be based out of Inuvik. It is possible to include one local youth interested in gaining field and lab-based training in permafrost and climate science. This would involve daytrip fieldwork carried out by boat on East Channel of the Mackenzie River, and preparation of ice samples at the Aurora Research Institute, which will be contracted out for isotope and geochemical analysis at other institutes. Upon successful completion of this research, the Principal Investigator (PI) will ensure that all reports and publications stemming from this work will be forwarded to the Aurora Research Institute (ARI) and all local stakeholders (Inuvialuit, Gwich’in) whose traditional lands overlap with the study area. The PI is also interested to give a public presentation in Inuvik upon completion of this project, and will reach out to ARI to coordinate this. In the scientific community, the PI anticipates this research will be presented in the peer-reviewed literature and at international geoscience conferences such as the American Geophysical Union Fall Meeting. The fieldwork for this study will be conducted from July 23, 2017 to August 2, 2017.
