project I
project I

project II

project III

project IV

project V

project VI

project VII

project VIII

project IX

project X

current vacancies

project I: analysis of long term trends

Using existing data (much of it unpublished) collected at several sites in Ontario, including Muskoka-Haliburton (Dorset), the Experimental Lakes Area (Kenora), and the Turkey Lakes Watersheds (Sault Ste. Marie), trends in key water quality parameters including sulphate, pH,alkalinity and DOC will be evaluated with respect to the impact of past changes in sulphur and nitrogen emissions and deposition. Although preliminary analysis of trends in water chemistry at these and other Canadian sites have been reported previously (Dillon et al. 1987, Jeffries et al. 1995, Clair et al. 1995), there has been no detailed analysis of most of the existing data, and no attempt to separate the influence of factors other than changes in sulphur deposition. Long-term records exist at these sites which will allow us to differentiate between natural variability, the effects of long-term patterns in climate variables, and changing acid deposition levels. The ELA site receives the lowest sulphur deposition of the three sites, and will be used as a control to assess the impact of climate variables. The Dorset site receives the highest deposition, and Turkey Lakes receives intermediate levels. The hypothesis that will be tested is that any long-term changes in lake chemistry observed at these sites can be separated into effects of climate signals (precipitation, temperature parameters) which can be differentiated from the effects of changes in sulphur and nitrogen deposition. The analysis of existing water chemistry data will be carried out by the chair-holder.

Paleolimnologic methods, based on diatoms and/or other algae that leave identifiable remains in lake sediments, are a second means of analyzing long-term trends in lake chemistry (Flower and Battarbee 1983). There is an excellent opportunity to evaluate the trends in the Dorset lakes using this methodology because of the availability of samples and data from Dr. J. Smol’s (Queens University) laboratory. Cores were collected from several Dorset lakes a number of years ago; the cores were sectioned at fine intervals, mounted, and the diatoms counted, but the data have not been analyzed or reported. These results can be compared with the real-time measurements made on the same lakes over ca. twenty years, a significant fraction of the time span to which the paleo work corresponds.

Projections about the changes expected in lake chemistry in the next five years resulting from changes in S and N deposition will also be made. A variety of modelling methodologies including empirical relationships such as the Henriksen titration model (Henriksen 1979), watershed-based mechanistic models such as MAGIC (Model of Acidification of Groundwater in Catchments) (Cosby et al. 1985) and regional-scale spatial models such as the stochastic version of MAGIC will be used to develop predictions about the expected impacts on basic water chemistry of incremental increases in deposition of acid procurers. Predicted changes in major ion chemistry, particularly pH and DOC will be used, in turn, to model expected changes in metal speciation using equilibrium models.