References

Biogeosciences

1726-4189

Copernicus Publications

Göttingen, Germany

10.5194/bg-10-6247-2013

Sources and fate of terrestrial dissolved organic carbon in lakes of a Boreal Plains region recently affected by wildfire

Olefeldt

https://orcid.org/0000-0002-5976-1475

¹ Devito

K. J.

² Turetsky

M. R.

Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada

Department of Biological Sciences, University of Alberta, Edmonton, AB N6A 5B7, Canada

02 10 2013

10 10 6247 6265

2013

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Downstream mineralization and sedimentation of terrestrial dissolved organic carbon (DOC) render lakes important for landscape carbon cycling in the boreal region. The chemical composition of terrestrial DOC, the downstream delivery of terrestrial DOC and its processing within aquatic ecosystem may all be influenced by climate change, including increased occurrence of wildfire. Here, we assessed composition and lability (during both dark- and UV incubations) of DOC from peatland groundwater and mineral soil groundwater, and from shallow lakes within a peatland-rich region on the Boreal Plains of western Canada that was recently affected by wildfire. Wildfire was found to increase aromaticity of DOC in peat pore water above the water table, but had no effect on the concentrations or composition of peatland groundwater DOC or mineral soil DOC. Using a mixing model we estimated that on average 98 and 78% of terrestrial DOC inputs to the lakes in fine- and coarse-textured settings, respectively, originated from peatland groundwater sources. Accordingly, lake DOC composition reflected primarily a mixing of peatland and mineral soil groundwater sources, with no detectable influence of the recent wildfire. Lake and peatland DOC had low biodegradability, lower than that of mineral soil DOC. However, both mineralization and sedimentation of peatland DOC increased substantially during UV incubations through selective removal of aromatic humic and fulvic acids. Similar shifts in DOC composition as observed during the UV incubations were also observed across lakes with longer water residence times. The mixing model estimated that on average 54% (95% confidence interval: 36–64%) of terrestrial DOC had been removed in lakes as a result of mineralization and sedimentation. Meanwhile, the reduction in absorbance at 254 nm was 71% (58–76%), which suggests selective removal of aromatic DOC. Hence, incubation results, patterns of DOC composition among lakes and mixing model results were consistent with significant within-lake removal of terrestrial DOC through UV-mediated processes. Selective removal of highly aromatic DOC through UV-mediated processes implies that organic sources that are considered stabile in terrestrial ecosystems can be readily mineralized once entering aquatic ecosystems. Together, our results suggest that regional characteristics (climate, surface geology and lake morphometry) can prevent wildfire from causing pulse perturbations to the linkages between terrestrial and aquatic C cycling and also regulate the processes that dominate within-lake removal of terrestrial DOC.

References 1

Ågren, A., Buffam, I., Berggren, M., Bishop, K., Jansson, M., and Laudon, H.: Dissolved organic carbon characteristics in boreal streams in a forest-wetland gradient during the transition between winter and summer, J. Geophys. Res.-Biogeo., 113, G03031, <a href="http://dx.doi.org/10.1029/2007jg000674">https://doi.org/10.1029/2007jg000674</a>, 2008.

Alberta Sustainable Resource Development, Government of Alberta: Historical wildfire perimeters of Alberta, available at: <a href="http://srd.alberta.ca/Wildfire/WildfireStatus/HistoricalWildfireInformation/SpatialWildfireData.aspx">http://srd.alberta.ca/Wildfire/WildfireStatus/HistoricalWildfireInformation/SpatialWildfireData.aspx</a>), (last access: 1 October 2013), 2013.

Algesten, G., Sobek, S., Bergström, A. K., Ågren, A., Tranvik, L. J., and Jansson, M.: Role of lakes for organic carbon cycling in the boreal zone, Glob. Change Biol., 10, 141–147, 2004.

Allen, E. W., Prepas, E. E., Gabos, S., Strachan, W., and Chen, W.: Surface water chemistry of burned and undisturbed watersheds on the Boreal Plain: an ecoregion approach, J. Environ. Eng. Sci., 2, S73–S86, <a href="http://dx.doi.org/10.1139/s03-035">https://doi.org/10.1139/s03-035</a>, 2003.

Arts, M. T., Robarts, R. D., Kasai, F., Waiser, M. J., Tumber, V. P., Plante, A. J., Rai, H., and de Lange, H. J.: The attenuation of ultraviolet radiation in high dissolved organic carbon waters of wetlands and lakes on the northern Great Plains, Limnol. Oceanogr., 45, 292–299, 2000.

Bade, D. L., Carpenter, S. R., Cole, J. J., Pace, M. L., Kritzberg, E., Van de Bogert, M. C., Cory, R. M., McKnight, D. M.: Sources and fate of dissolved organic carbon in lakes as determined by whole-lake carbon isotope additions, Biogeochemistry, 84, 115–129, <a href="http://dx.doi.org/10.1007/s10533-006-9013-y">https://doi.org/10.1007/s10533-006-9013-y</a>, 2007.

Balcarczyk, K. L., Jones, J. B., Jaffe, R., and Maie, N.: Stream dissolved organic matter bioavailability and composition in watersheds underlain with discontinuous permafrost, Biogeochemistry, 94, 255–270, <a href="http://dx.doi.org/10.1007/s10533-009-9324-x">https://doi.org/10.1007/s10533-009-9324-x</a>, 2009.

Bayley, S. E., Creed, I. F., Sass, G. Z., and Wong, A. S.: Frequent regime shifts in trophic states in shallow lakes on the Boreal Plain: Alternative "unstable" states?, Limnol. Oceanogr., 52, 2002–2012, <a href="http://dx.doi.org/10.4319/lo.2007.52.5.2002">https://doi.org/10.4319/lo.2007.52.5.2002</a>, 2007.

Benner, R. and Kaiser, K.: Biological and photochemical transformations of amino acids and lignin phenols in riverine dissolved organic matter, Biogeochemistry, 102, 209–222, <a href="http://dx.doi.org/10.1007/s10533-010-9435-4">https://doi.org/10.1007/s10533-010-9435-4</a>, 2011.

Berggren, M., Ström, L., Laudon, H., Karlsson, J., Jonsson, A., Giesler, R., Bergström, A.-K., and Jansson, M.: Lake secondary production fuelled by rapid transfer of low molecular weight organic carbon from terrestrial sources to aquatic consumers, Ecol. Lett., 13, 870–880, <a href="http://dx.doi.org/10.1111/j.1461-0248.2010.01483.x">https://doi.org/10.1111/j.1461-0248.2010.01483.x</a>, 2010.

Bertilsson, S. and Tranvik, L. J.: Photochemical transformation of dissolved organic matter in lakes, Limnol. Oceanogr., 45, 753–762, 2000.

Betts, E. F. and Jones, J. B.: Impact of Wildfire on Stream Nutrient Chemistry and Ecosystem Metabolism in Boreal Forest Catchments of Interior Alaska, Arct. Antarct. Alp. Res., 41, 407–417, <a href="http://dx.doi.org/10.1657/1938-4246-41.4.407">https://doi.org/10.1657/1938-4246-41.4.407</a>, 2009.

Brinkmann, T., Horsch, P., Sartorius, D., and Frimmel, F. H.: Photoformation of low-molecular-weight organic acids from brown water dissolved organic matter, Environ. Sci. Technol., 37, 4190–4198, <a href="http://dx.doi.org/10.1021/es0263339">https://doi.org/10.1021/es0263339</a>, 2003.

Canadian Forest Service: National Fire Database – Agency FireData, Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, Edmonton, Alberta, <a href="http://cwfis.cfs.nrcan.gc.ca/en_CA/nfdb">http://cwfis.cfs.nrcan.gc.ca/en_CA/nfdb</a>, (last access: 1 October 2013), 2011.

Carignan, R., D'Arcy, P., and Lamontagne, S.: Comparative impacts of fire and forest harvesting on water quality in Boreal Shield lakes, Can. J. Fish. Aquat. Sci., 57, 105–117, 2000.

Certini, G.: Effects of fire on properties of forest soils: a review, Oecologia, 143, 1–10, <a href="http://dx.doi.org/10.1007/s00442-004-1788-8">https://doi.org/10.1007/s00442-004-1788-8</a>, 2005.

Coble, P. G.: Characterization of marine and terrestrial DOM in seawater using excitation emission matrix spectroscopy, Mar. Chem., 51, 325–346, <a href="http://dx.doi.org/10.1016/0304-4203(95)00062-3">https://doi.org/10.1016/0304-4203(95)00062-3</a>, 1996.

Cory, R. M., Crump, B. C., Dobkowski, J. A., and Kling, G. W.: Surface exposure to sunlight stimulates CO2 release from permafrost soil carbon in the Arctic, P. Natl. Acad. Sci. USA, 110, 3429–3434, <a href="http://dx.doi.org/10.1073/pnas.1214104110">https://doi.org/10.1073/pnas.1214104110</a>, 2013.

Creed, I. F., Beall, F. D., Clair, T. A., Dillon, P. J., and Hesslein, R. H.: Predicting export of dissolved organic carbon from forested catchments in glaciated landscapes with shallow soils, Global Biogeochem. Cy., 22, GB4024, <a href="http://dx.doi.org/10.1029/2008gb003294">https://doi.org/10.1029/2008gb003294</a>, 2008.

Devito, K., Creed, I., Gan, T., Mendoza, C., Petrone, R., Silins, U., and Smerdon, B.: A framework for broad-scale classification of hydrologic response units on the Boreal Plain: is topography the last thing to consider?, Hydrol. Process., 19, 1705–1714, <a href="http://dx.doi.org/10.1002/hyp.5881">https://doi.org/10.1002/hyp.5881</a>, 2005.

EcoRegions Working Group: Ecoclimatic Regions of Canada, First Approximation, Ecological Land Classification Series, No 23, 119 pp., Environment Canada, Ottawa, 1989.

Fellman, J. B., Hood, E., and Spencer, R. G. M.: Fluorescence spectroscopy opens new windows into dissolved organic matter dynamics in freshwater ecosystems: A review, Limnol. Oceanogr., 55, 2452–2462, <a href="http://dx.doi.org/10.4319/lo.2010.55.6.2452">https://doi.org/10.4319/lo.2010.55.6.2452</a>, 2010.

Fenton, M. M., Paulen, R. C., and Pawlowicz, J. G.: Surficial geology of the Lubicon Lake area, Alberta (NTS 84B/SW), Alberta Geological Survey, Edmonton, 2003.

Ferone, J.: Landscape controls of hydrologic function and phosphorous dynamics in two pond-wetland complexes on the mixedwood boreal plain, M.Sc. Thesis, Biological Sciences, University of Alberta, Edmonton, Alberta, 159 pp., 2001.

Ferone, J. M. and Devito, K. J.: Shallow groundwater-surface water interactions in pond-peatland complexes along a Boreal Plains topographic gradient, J. Hydrol., 292, 75–95, <a href="http://dx.doi.org/10.1016/j.jhydrol.2003.12.032">https://doi.org/10.1016/j.jhydrol.2003.12.032</a>, 2004.

Flannigan, M., Stocks, B., Turetsky, M., and Wotton, M.: Impacts of climate change on fire activity and fire management in the circumboreal forest, Glob. Change Biol., 15, 549–560, <a href="http://dx.doi.org/10.1111/j.1365-2486.2008.01660.x">https://doi.org/10.1111/j.1365-2486.2008.01660.x</a>, 2009.

Gibbons, Z.: The influence of groundwater flow on phosphate dynamics in three riparian wetlands surrounding an outwash lake in northern Alberta, MSc thesis, Department of Biological Sciences, University of Alberta, Edmonton, Alberta, 95 pp., 2005.

Graneli, W., Lindell, M., and Tranvik, L.: Photo-oxidative production of dissolved inorganic carbon in lakes of different humic content, Limnol. Oceanogr., 41, 698–706, 1996.

Hargreaves, G. H. and Samani, Z. A.: Estimation of potential evapotranspiration, Journal of Irrigation and Drainage Division, Proceedings of the American Society of Civil Engineers, 108, 223–230, 1982.

Hockaday, W. C., Grannas, A. M., Kim, S., and Hatcher, P. G.: The transformations and mobility of charcoal in fire-impacted watersheds, Geochim. Cosmochim. Ac., 71, 3432–3445, <a href="http://dx.doi.org/10.1016/j.gca.2007.02.023">https://doi.org/10.1016/j.gca.2007.02.023</a>, 2007.

Holmes, R. M., McClelland, J. W., Raymond, P. A., Frazer, B. B., Peterson, B. J., and Stieglitz, M.: Lability of DOC transported by Alaskan rivers to the Artic Ocean, Geophys. Res. Lett., 35, L03402, <a href="http://dx.doi.org/10.1029/2007GL032837">https://doi.org/10.1029/2007GL032837</a>, 2008.

Jonsson, A., Meili, M., Bergström, A. K., and Jansson, M.: Whole-lake mineralization of allochthonous and autochthonous organic carbon in a large humic lake (Ortrasket, N. Sweden), Limnol. Oceanogr., 46, 1691–1700, 2001.

Kaiser, K. and Kalbitz, K.: Cycling downwards – dissolved organic matter in soils, Soil Biol. Biochem., 52, 29–32, <a href="http://dx.doi.org/10.1016/j.soilbio.2012.04.002">https://doi.org/10.1016/j.soilbio.2012.04.002</a>, 2012.

Kalbitz, K., Schmerwitz, J., Schwesig, D., and Matzner, E.: Biodegradation of soil-derived dissolved organic matter as related to its properties, Geoderma, 113, 273–291, <a href="http://dx.doi.org/10.1016/S0016-7061(02)00365-8">https://doi.org/10.1016/S0016-7061(02)00365-8</a>, 2003a.

Kalbitz, K., Schwesig, D., Schmerwitz, J., Kaiser, K., Haumaier, L., Glaser, B., Ellerbrock, R., and Leinweber, P.: Changes in properties of soil-derived dissolved organic matter induced by biodegradation, Soil Biol. Biochem., 35, 1129–1142, <a href="http://dx.doi.org/10.1016/S0038-0717(03)00165-2">https://doi.org/10.1016/S0038-0717(03)00165-2</a>, 2003b.

Kicklighter, D. W., Hayes, D., McClelland, J., Peterson, B. J., McGuire, A. D., and Melillo, J. M.: Insights and issues with simulating terrestrial DOC export of arctic river networks, Ecol. Appl., <a href="http://dx.doi.org/10.1890/11-1050.1">https://doi.org/10.1890/11-1050.1</a>, in press, 2013.

Koehler, B., von Wachenfeldt, E., Kothawala, D., and Tranvik, L. J.: Reactivity continuum of dissolved organic carbon decomposition in lake water, J. Geophys. Res.-Biogeo., 117, G01024, <a href="http://dx.doi.org/10.1029/2011jg001793">https://doi.org/10.1029/2011jg001793</a>, 2012.

Kothawala, D. N., Roehm, C., Blodau, C., and Moore, T. R.: Selective adsorption of dissolved organic matter to mineral soils, Geoderma, 189, 334–342, 2012a.

Kothawala, D. N., von Wachenfeldt, E., Koehler, B., and Tranvik, L. J.: Selective loss and preservation of lake water dissolved organic matter fluorescence during long-term dark incubations, Sci. Total Environ., 433, 238–246, <a href="http://dx.doi.org/10.1016/j.scitotenv.2012.06.029">https://doi.org/10.1016/j.scitotenv.2012.06.029</a>, 2012b.

Lamontagne, S., Carignan, R., D'Arcy, P., Prairie, Y. T., and Pare, D.: Element export in runoff from eastern Canadian Boreal Shield drainage basins following forest harvesting and wildfires, Can. J. Fish. Aquat. Sci., 57, 118–128, 2000.

Marchand, D., Prairie, Y. T., and del Giorgio, P. A.: Linking forest fires to lake metabolism and carbon dioxide emissions in the boreal region of Northern Quebec, Glob. Change Biol., 15, 2861–2873, <a href="http://dx.doi.org/10.1111/j.1365-2486.2009.01979.x">https://doi.org/10.1111/j.1365-2486.2009.01979.x</a>, 2009.

Marshall, I. B., Schut, P., and Ballard, M.: A National Ecological Framework for Canada: Attribute Data. Environmental Quality Branch, Ecosystems Science Directorate, Environment Canada and Research Branch, Agriculture and Agri-Food Canada, Ottawa, <a href="http://sis.agr.gc.ca/cansis/nsdb/ecostrat/1999report/index.html">http://sis.agr.gc.ca/cansis/nsdb/ecostrat/1999report/index.html</a>, (last access: 26 February 2013), 1999.

Mattsson, T., Kortelainen, P., and Raike, A.: Export of DOM from boreal catchments: impacts of land use cover and climate, Biogeochemistry, 76, 373–394, <a href="http://dx.doi.org/10.1007/s10533-005-6897-x">https://doi.org/10.1007/s10533-005-6897-x</a>, 2005.

McCallister, S. L. and del Giorgio, P. A.: Evidence for the respiration of ancient terrestial organic C in northern temperate lakes and streams, P. Natl. Acad. Sci. USA, 109, 16963–16968, <a href="http://dx.doi.org/10.1073/pnas.1207305109">https://doi.org/10.1073/pnas.1207305109</a>, 2012.

McEachern, P., Prepas, E. E., Gibson, J. J., and Dinsmore, W. P.: Forest fire induced impacts on phosphorus, nitrogen, and chlorophyll a concentrations in boreal subarctic lakes of northern Alberta, Can. J. Fish. Aquat. Sci., 57, 73–81, 2000.

Moran, M. A., Sheldon, W. M., and Zepp, R. G.: Carbon loss and optical property changes during long-term photochemical and biological degradation of estuarine dissolved organic matter, Limnol. Oceanogr., 45, 1254–1264, 2000.

Neff, J. C., Harden, J. W., and Gleixner, G.: Fire effects on soil organic matter content, composition, and nutrients in boreal interior Alaska, Can. J. For. Res.-Rev. Can. Rech. For., 35, 2178–2187, <a href="http://dx.doi.org/10.1139/x05-154">https://doi.org/10.1139/x05-154</a>, 2005.

Obernosterer, I. and Benner, R.: Competition between biological and photochemical processes in the mineralization of dissolved organic carbon, Limnol. Oceanogr., 49, 117–124, 2004.

Ohno, T.: Fluorescence inner-filtering correction for determining the humification index of dissolved organic matter, Environ. Sci. Technol., 36, 742–746, <a href="http://dx.doi.org/10.1021/es0155276">https://doi.org/10.1021/es0155276</a>, 2002.

Olefeldt, D., Roulet, N., Giesler, R., and Persson, A.: Total waterborne carbon export and DOC composition from ten nested subarctic peatland catchments – importance of peatland cover, groundwater influence, and inter-annual variability of precipitation patterns, Hydrol. Process., 27, 2280–2294, <a href="http://dx.doi.org/10.1002/hyp.9358">https://doi.org/10.1002/hyp.9358</a>, 2013a.

Olefeldt, D., Turetsky, M., and Blodau, C.: Altered composition and microbial versus UV-mediated degradation of dissolved organic matter in boreal soils following wildfire, Ecosystems, in press, <a href="http://dx.doi.org/10.1007/s10021-013-9691-y">https://doi.org/10.1007/s10021-013-9691-y</a>, 2013b.

Pinel-Alloul, B., Prepas, E., Planas, D., Steedman, R., and Charette, T.: Watershed impacts of logging and wildfire: Case studies in Canada, Lake Reserv. Manage., 18, 307–318, 2002.

Plummer, L. N. and Busenberg, E.: The solubilities of calcite, aragonite and vaterite in CO2-H2O solutions between 0 and 90 °C, and an evaluation of the aquous model for the system CaCO3-CO2-H2O, Geochim. Cosmochim. Ac., 46, 1011–1040, 1982.

Prairie, Y. T.: Carbocentric limnology: looking back, looking forward, Can. J. Fish. Aquat. Sci., 65, 543–548, <a href="http://dx.doi.org/10.1139/f08-011">https://doi.org/10.1139/f08-011</a>, 2008.

Redding, T. E. and Devito, K. J.: Lateral flow thresholds for aspen forested hillslopes on the Western Boreal Plain, Alberta, Canada, Hydrol. Process., 22, 4287–4300, <a href="http://dx.doi.org/10.1002/hyp.7038">https://doi.org/10.1002/hyp.7038</a>, 2008.

Roehm, C. L., Giesler, R., and Karlsson, J.: Bioavailability of terrestrial organic carbon to lake bacteria: The case of a degrading permafrost mire complex, J. Geophys. Res.-Biogeo., 114, G03006, <a href="http://dx.doi.org/10.1029/2008JG000863">https://doi.org/10.1029/2008JG000863</a>, 2009.

Sass, G. Z. and Creed, I. F.: Characterizing hydrodynamics on boreal landscapes using archived synthetic aperture radar imagery, Hydrol. Process., 22, 1687–1699, <a href="http://dx.doi.org/10.1002/hyp.6736">https://doi.org/10.1002/hyp.6736</a>, 2008.

Sass, G. Z., Creed, I. F., Bayley S. E., and Devito K. J.: Interannual variability in trophic status of shallow lakes on the Boreal Plain: Is there a climate signal?, Water Resour. Res., 44, W08443, <a href="http://dx.doi.org/10.1029/2007WR006310">https://doi.org/10.1029/2007WR006310</a>, 2008.

Schindler, D. W., Bayley, S. E., Parker, B. R., Beaty, K. G., Cruikshank, D. R., Fee, E. J., Schindler, E. U., and Stainton, M. P.: The effects of climatic warming on the properties of boreal lakes and streams at the Experimental Lakes Area, northwestern Ontario, Limnol. Oceanogr., 41, 1004–1017, 1996.

Smerdon, B. D., Devito, K. J., and Mendoza, C. A.: Interaction of groundwater and shallow lakes on outwash sediments in the sub-humid Boreal Plains of Canada, J. Hydrol., 314, 246–262, <a href="http://dx.doi.org/10.1016/j.jhydrol.2005.04.001">https://doi.org/10.1016/j.jhydrol.2005.04.001</a>, 2005.

Smerdon, B. D., Mendoza, C. A., and Devito, K. J.: Influence of subhumid climate and water table depth on groundwater recharge in shallow outwash aquifers, Water Resour. Res., 44, W08427, <a href="http://dx.doi.org/10.1029/2007wr005950">https://doi.org/10.1029/2007wr005950</a>, 2008.

Sobek, S., Tranvik, L. J., and Cole, J. J.: Temperature independence of carbon dioxide supersaturation in global lakes, Global Biogeochem. Cy., 19, Gb2003, <a href="http://dx.doi.org/10.1029/2004gb002264">https://doi.org/10.1029/2004gb002264</a>, 2005.

Stedmon, C. A. and Bro, R.: Characterizing dissolved organic matter fluorescence with parallel factor analysis: a tutorial, Limnol. Oceanogr.-Meth., 6, 572–579, 2008.

Stubbins, A., Niggemann, J., and Dittmar, T.: Photo-lability of deep ocean dissolved black carbon, Biogeosciences, 9, 1661–1670, <a href="http://dx.doi.org/10.5194/bg-9-1661-2012">https://doi.org/10.5194/bg-9-1661-2012</a>, 2012.

Tranvik, L. J. and Bertilsson, S.: Contrasting effects of solar UV radiation on dissolved organic sources for bacterial growth, Ecol. Lett., 4, 458–463, <a href="http://dx.doi.org/10.1046/j.1461-0248.2001.00245.x">https://doi.org/10.1046/j.1461-0248.2001.00245.x</a>, 2001.

Tranvik, L. J., Downing, J. A., Cotner, J. B., Loiselle, S. A., Striegl, R. G., Ballatore, T. J., Dillon, P., Finlay, K., Fortino, K., Knoll, L. B., Kortelainen, P. L., Kutser, T., Larsen, S., Laurion, I., Leech, D. M., McCallister, S. L., McKnight, D. M., Melack, J. M., Overholt, E., Porter, J. A., Prairie, Y., Renwick, W. H., Roland, F., Sherman, B. S., Schindler, D. W., Sobek, S., Tremblay, A., Vanni, M. J., Verschoor, A. M., von Wachenfeldt, E., and Weyhenmeyer, G. A.: Lakes and reservoirs as regulators of carbon cycling and climate, Limnol. Oceanogr., 54, 2298–2314, 2009.

Turetsky, M. R., Kane, E. S., Harden, J. W., Ottmar, R. D., Manies, K. L., Hoy, E., and Kasischke, E. S.: Recent acceleration of biomass burning and caron losses in Alaskan forests and peatlands, Nat. Geosci., 4, 27–31, <a href="http://dx.doi.org/10.1038/NGEO1027">https://doi.org/10.1038/NGEO1027</a>, 2010.

Vogwill, R.: Hydrogeology of the Lesser Slave Lake area, Alberta, Edmonton AB, Alberta Research Council, 1978.

von Wachenfeldt, E., Sobek, S., Bastviken, D., and Tranvik, L. J.: Linking allochthonous dissolved organic matter and boreal lake sediment carbon sequestration: The role of light-mediated flocculation, Limnol. Oceanogr., 53, 2416–2426, 2008.

Wassenaar, L. I., Hendrey, M. J., Chostner, V. L., and Lis, G. P.: High resolution pore water δ2H and δ18O measurements by H2O$_(liquid)$ - H2O$_(vapour)$ equilibration laser spectroscopy, Environ. Sci. Technol., 42, 9262–9267, <a href="http://dx.doi.org/10.1021/es802065s">https://doi.org/10.1021/es802065s</a>, 2008.

Weishaar, J. L., Aiken, G. R., Bergamaschi, B. A., Fram, M. S., Fujii, R., and Mopper, K.: Evaluation of specific ultraviolet absorbance as an indicator of the chemical composition and reactivity of dissolved organic carbon, Environ. Sci. Technol., 37, 4702–4708, <a href="http://dx.doi.org/10.1021/Es030360x">https://doi.org/10.1021/Es030360x</a>, 2003.

Weyhenmeyer, G. A., Fröberg, M., Karltun, E., Khalili, M., Kothawala, D., Temnerud, J., and Tranvik, L. J.: Selective decay of terrestrial organic carbon during transport from land to sea, Glob. Change Biol., 18, 349–355, <a href="http://dx.doi.org/10.1111/j.1365-2486.2011.02544.x">https://doi.org/10.1111/j.1365-2486.2011.02544.x</a>, 2012.

Wickland, K. P., Neff, J. C., and Aiken, G. R.: Dissolved organic carbon in Alaskan boreal forest: Sources, chemical characteristics, and biodegradability, Ecosystems, 10, 1323–1340, <a href="http://dx.doi.org/10.1007/s10021-007-9101-4">https://doi.org/10.1007/s10021-007-9101-4</a>, 2007.