Canadian Forest Service Publications

Temporal trends in water chemistry in the Turkey Lakes Watershed, Ontario, Canada, 1982-1999. 2002. Jeffries, D.S.; Semkin, R.G.; Beall, F.D.; Franklyn, J. Water, Air, and soil Pollution: Focus 2: 5-22.

Year: 2002

Issued by: Great Lakes Forestry Centre

Catalog ID: 21503

Language: English

Availability: PDF (request by e-mail)

Mark record

Abstract

The Turkey Lakes Watershed (TLW) was established in 1980 as a site for study of the ecosystem effects of acidic deposition, and since then there has been ~40% reduction in North American SO2 emissions. Monitoring records for bulk deposition, shallow and deep ground water, two headwater streams and two lake outflows have been tested to identify statistically significant monotonic trends. The TLW appears to be responding to declining acidifying emissions because the most prevalent chemical trend across sample types/stations was decreasing SO42-. Increasing pH was detected in four of the seven data sets, but only the H+ decrease in bulk deposition was of a magnitude to be an important ionic compensation for the SO42- decline. There is little evidence of acidification recovery in TLW waters however. Increasing alkalinity was found only in the outflow of the penultimate lake of the basin, and in fact, deep ground water and the other lake outflow had decreasing alkalinity trends (i.e., continuing acidification). For the surface water stations, the greater part of the ionic compensation for declining SO42- was decreasing base cations, and as a result, these waters are probably becoming more dilute with time, although only the headwater streams exhibited declining conductivity. Five of seven data sets had increasing dissolved organic carbon concentrations. Increasing NO3- was important in ground waters. Drought has strongly influenced trends and delayed recovery by mobilizing S stored in catchment wetlands and/or soils.