A Changing Climate, A Changing Arctic: Investigating biogeochemical cycling in the Canadian High Arctic

Overview

Canada has the longest coastline in the world and more than 40% of it is situated along the frozen shores of the Canadian Arctic Archipelago (CAA), where glaciers and permafrost are defining coastal features. Rapid climate warming in the Arctic is however dramatically altering the characteristics of this coast and its adjacent coastal waters via glacier mass loss and retreat and permafrost thaw ( e.g. Peterson et al., 2002; White et al., 2007; Zhang et al., 2008). Coastal rivers weathering these landscapes provide important fluxes of freshwater, sediment, and carbon to the ocean. Thus, changes to these catchments will impact more broadly on the wider Arctic marine environment (e.g. Carmack et al., 2016), as marine waterways in the CAA are important regions of geochemical modification for outflowing Arctic Ocean waters en route to Baffin Bay and the North Atlantic. Recent studies (e.g. Brown et al., 2020) have illustrated the unique carbon contributions that small rivers draining the vast land area encompassed by the CAA’s high Arctic islands may make to marine waters. Rivers draining glacier and permafrost systems can mobilize labile, aged terrestrial organic carbon to coastal ecosystems where it can be respired by marine microorganisms and returned to the atmosphere. As glacial coverage decreases and permafrost regions thaw, weathering and carbon fluxes are predicted to increase. This project will address fundamental gaps in our understanding of land-to-ocean weathering and carbon fluxes from glacial and permafrost sourced rivers in the high Arctic through a combination of field work and geochemical lab work. Working closely with local Inuit communities, this study will integrate Inuit knowledge and skill into the collection and interpretation of observations with the aim of advancing understanding of local environmental conditions, while simultaneously addressing critical questions of regional climate impacts.

Methodology

The fieldwork will be based in Grise Fiord, Nunavut, home to the Inuit hamlet of Ausuittuq, the northern most community in Canada. Grise Fiord is surrounded by melting glaciers and thawing permafrost, with rivers draining this landscape draining into Jones Sound, a major waterway in the CAA. We will conduct both a high-resolution temporal study at nearby sites and a broader spatial survey via helicopter. A local Inuit hunter boat will be used to collect samples in the river deltas.
Samples will be analysed at the STAiG laboratories in St Andrews for major elemental concentrations, total carbon and alkalinity, as well as sulfur and uranium isotopes to constrain key components of the weathering regime and fluxes into the marine realm. On key samples, radiocarbon measurements on DIC, DOC, and POC will be made at the NEIF Radiocarbon Laboratory (SUERC) under the supervision of Dr Mark Garnett.

Project Timeline

Year 1

Literature review, training in clean laboratory methods and mass spectrometry at the STAiG laboratory. Initial analyses of existing samples. Field work to collect samples in the Canadian High Arctic in the summer of the first year.

Year 2

Analysis of elemental concentrations and isotopes on samples. Research trip to SUERC to analyse radiocarbon. Second field campaign in the Canadian High Arctic. Present results at a national conference (e.g. GGRIP meeting).

Year 3

Finish remaining sample measurements on second season samples, finalize data sets, prepare written manuscripts. Present results at international conference (e.g. EGU or AGU)

Year 3.5

Finish writing thesis.

Training
& Skills

The student will gain specific training in fieldwork and geochemical laboratory techniques including ion chromatography, mass spectrometry, and clean lab chemistry, as well as training and expertise in radiocarbon measurements, weathering, and isotope geochemistry. The student will be trained and work with MC-ICP-MS. The student will also be trained in Matlab, Python, or R to process and analyse data and model results. Furthermore, over the course of the PhD the student will gain transferable skills such as field campaign planning, scientific writing, statistics and data analysis, and problem-solving, as well as time management and working towards a long-term goal.

References & further reading

Brown, K. A., et al. (2020). Geochemistry of small Canadian Arctic Rivers with diverse geological and hydrological settings. Journal of Geophysical Research: Biogeosciences, 125, e2019JG005414. https://doi.org/10.1029/2019JG005414

Carmack, E. C., et al. (2016), Freshwater and its role in the Arctic Marine System: Sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans, J. Geophys. Res. Biogeosci., 121,675–717, doi:10.1002/2015JG003140

Peterson, B. J., et al. (2006). Trajectory shifts in the Arctic and subarctic
freshwater cycle. Science, 313(5790), 1061–1066. https://doi.org/10.1126/science.1122593

Peterson, B. J., et al. (2006). Trajectory shifts in the Arctic and subarctic freshwater cycle. Science, 313(5790), 1061–1066. https://doi.org/10.1126/science.1122593

White, D., et al. (2007). The Arctic freshwater system: Changes and impacts. Journal of Geophysical Research, 112, G04S54. http://doi.org/10.1029/2006JGO00353

Zhang, Y., et al. (2008). Transient projections of permafrost distribution in Canada during the 21st century under scenarios of climate change. Global and Planetary Change, 60(3–4), 443–456. http://doi.org/10.1016/j.gloplacha.2007.05.003

Further Information

For further information contact:

Dr Andrea Burke
ab276@st-andrews.ac.uk

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