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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2018-253
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
15 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Seasonal shifts in export of DOC and nutrients from burned and unburned peatland-rich catchments, Northwest Territories, Canada
Katheryn Burd1, Suzanne E. Tank2, Nicole Dion3, William L. Quinton4, Christopher Spence5, Andrew J. Tanentzap6, and David Olefeldt1 1Department of Renewable Resources, University of Alberta, Edmonton, T6G 2R3, Canada
2Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9, Canada
3Water Resources Department, Government of Northwest Territories, Yello w knife, X1A 2L9, Canada
4Centre for Cold Regions and Water Science, Wilfred Laurier University, Waterloo, N2L 3C5, Canada
5National Hydrology Research Centre, Environment and Climate Change Canada, Saskatoon, S7N 3H5, Canada
6Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA United Kingdom
Abstract. Boreal peatlands are major catchment sources of dissolved organic carbon (DOC) and nutrients, and thus strongly regulate the landscape carbon balance, aquatic food webs, and downstream water quality. Climate change is likely to influence catchment solute yield directly through climatic controls on runoff generation, but also indirectly through altered disturbance regimes. In this study we monitored water chemistry from early spring until fall at the outlets of a 321 km2 catchment that burned 3 years prior to the study and a 134 km2 undisturbed catchment. Both catchments were located in the discontinuous permafrost zone of boreal western Canada and had ~60 % peatland cover. The two catchments had strong similarities in the timing of DOC and nutrient yields, but a few differences were consistent with anticipated effects of wildfire based on peatland porewater analysis. The four week spring period, particularly the rising limb of spring freshet, was crucial for accurate characterization of the seasonal solute yield from both catchments. The spring period was responsible for ~65 % of the seasonal DOC and nitrogen, and ~85 % of the phosphorous yield. The rising limb of spring freshet was associated with high phosphorous concentrations and DOC of distinctly high aromaticity and molecular weight. Shifts in stream DOC concentrations and aromaticity outside the early spring period were consistent with shifts in relative stream-flow contribution from precipitation-like water in the spring, to mineral soil groundwater in the summer, with consistent relative contributions from organic soil porewater. Radiocarbon content (14C) of DOC at the outlets was modern throughout May to September (fM: 0.99–1.05), but likely reflected a mix of aged DOC, e.g. porewater DOC from permafrost (fM: 0.65–0.85) and non-permafrost peatlands (fM: 0.95–1.00), with modern bomb-influenced DOC, e.g. DOC leached from forest litter (fM: 1.05–1.10). The burned catchment had significantly increased total phosphorous yield, and also had greater DOC yield during summer which was characterized by a greater contribution from aged DOC. Overall, however, our results suggest that DOC composition and yield from peatland-rich catchments in the discontinuous permafrost region likely is more sensitive to climate change through impacts on runoff generation rather than through altered fire regimes.
Citation: Burd, K., Tank, S. E., Dion, N., Quinton, W. L., Spence, C., Tanentzap, A. J., and Olefeldt, D.: Seasonal shifts in export of DOC and nutrients from burned and unburned peatland-rich catchments, Northwest Territories, Canada, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-253, in review, 2018.
Katheryn Burd et al.
Katheryn Burd et al.
Katheryn Burd et al.

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Short summary
In this study we investigated whether climate change and wildfires are likely to alter water quality of streams in western boreal Canada, a region that contains large permafrost-affected peatlands. We monitored stream discharge and water quality from early snowmelt to fall in two streams, one which drained a recently burned landscape. Wildfire increased the stream delivery of phosphorous, and possibly increased the release of old natural organic matter previously stored in permafrost soils.
In this study we investigated whether climate change and wildfires are likely to alter water...
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