By Chad Luider (MSc Condidate) and Erinn Radomske (MSc Candidate) of Okanagan University College, 3333 College Way, Kelowna BC V1V 1V7. For further information please contact us by email at cluider@hotmail.com or eradomsk@hotmail.com. Acknowledgments: Many thanks to Friends of Mt Revelstoke and Glacier, the National Science and Engineering Council of Canada (NSERC) and Okanagan University College for funding or supporting this project. Also many thanks to Bill Brown and Susan Hall of Parks Canada for information on lakes within Mount Revelstoke National Park and for helping with the necessary permits that were required for sample collection.  In August of 2001 we collected water samples from 13 lakes within Mount Revelstoke National Park. The purpose of sampling these lakes was to assess the concentration and composition of dissolved organic matter (DOM) in alpine systems. DOM plays an important role in protecting systems from metal pollutants, such as dissolved copper, lead, silver and mercury. DOM chemically complexes these metal pollutants, thus reducing toxic effects to fish and other organisms. The objective of this research was to better understand how the concentration and composition of DOM varies among systems and how this variation affects the protective properties of DOM.
DOM is derived from land (allochthonous) from the breakdown of plant material in soils or from within lake systems (autochthonous) from microbial productivity. Allochthonous DOM is typically darker in color, contributes the bulk of DOM to aquatic systems and more effectively reduces metal toxicity, as compared to autochthonous DOM. Therefore, the sensitivity of alpine lakes to metal contamination will depend on the relative contribution of allochthonous and autochthonous DOM, which will vary as a function of watershed properties. For example, watersheds with productive soils will typically exhibit higher contributions of allochthonous DOM to creeks, streams and lakes. The alpine environment provides a unique opportunity to investigate watershed control over the concentration and composition of DOM within lakes because there is sharp gradient in watershed properties. Watersheds vary from being dominated by rock and ice to being dominated by alpine vegetation, such as engelmann spruce and sub-alpine fir. The drainage basin of each lake sampled for this research was identified and characterized according to the percentage of the basin that was composed of rock, glacial ice and alpine vegetation. These watershed properties were then compared to the concentration and compositional properties of DOM within each system. The concentration of DOM is typically measured as, and will hereafter be referred to as, dissolved organic carbon (DOC). Compositional properties that were measured for this research include optical characteristics, such as colour, and copper binding properties. The results of this research indicate that DOC concentrations are low in all the alpine lakes sampled (< 1 C-mg L-1), although there is a significant decrease in DOC from watersheds dominated by alpine vegetation to watersheds dominated by rock and ice. In addition, optical measures suggest that the DOC in these systems is primarily from autochthonous sources, which is consistent with previous research. These results imply that alpine lakes are potentially very sensitive to metal deposition because autochthonous DOC is a very poor metal binder. Autochthonous DOC represents the lower extreme of copper complexation, thus providing only minimal protection to aquatic organisms from metal pollutants.
Refer to references listed below for more information or contact us at the following email addresses: cluider@hotmail.com or eradomsk@hotmail.com. Clow, D. W. and Sueker, J. K. 2000. Relations between basin characteristics and stream water chemistry in alpine/subalpine basins in Rocky Mountain National Park, Colorado. Water Resources Research. 36: 49-91. McKnight, D. M., Andrews, E. D., Spaulding, S. A., and Aiken, G. R. 1994. Aquatic fulvic acids in algal-rich Antarctic ponds. Limnology and Oceanography. 39: 1972-1979. Playle, R. C., Dixon, D. G., and Burnison, K. 1993. Copper and cadmium binding to fish gills: modification by organic carbon and synthetic ligands. Canadian Journal of Fisheries and Aquatic Science. 50: 2667-2677. Richards, J. G., Curtis, P. J., Burnison, B. K., and Playle, R. C. Effects of natural organic matter sources on reducing metal toxicity to rainbow trout (Oncorhynkus mykiss) and on metal binding to their gills. Setac Press. 20: 1159-1166. Vinebrooke, R. D. and Leavitt, P. R. 1998. Direct and interactive effects of allochthonous dissolved organic matter, inorganic nutrients, and ultraviolet radiation on an alpine littoral food web. Limnology and Oceanography. 43: 1065-1081.
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