Turkey Lakes Watershed Study reference list: 1995

Surface water concentrations were analyzed at 111 sites from central Ontario to Newfoundland, and precipitation composition and deposition analyzed for trends at six sites, including Algoma at the TLW.  H⁺ and SO₄ concentrations are decreasing in Ontario. In Quebec, pH and ANC are decreasing while NO₃ is increasing. At the Atlantic sites, pH and ANC are increasing. The 111 surface water sites were classified according to the acidification status: 60 are stable, 17 acidifying, and 34 improving.

This report attempts to determine whether sufficient data exists to form a policy for control of NO_x emissions. A table is presented showing percent of low, moderate and high concentrations of NO₃ across Canada in data segregated to reflect the seasonal concentration cycle normally observed for NO₃. Recommendations are made as to future work needed to calculate critical loads and fill in gaps in current knowledge.

A significant revision of 88-03.

This chapter gives an overview of process descriptions, assumptions, constraints and other considerations which enter into the development of deterministic watershed acidification models. Various approaches to acidification modelling are described. Four models (TMWAM, ETD, ILWAS and RAINS) are reviewed and a comparison of model performance is presented for the Turkey Lakes Watershed, Ontario, Canada.

Atmospheric deposition and surface water chemistry at 5 geologically sensitive sites in southeastern Canada have been monitored. Surface water data from 9 stations in Quebec and central Ontario collected over 13 years were analyzed for monotonic trends. While Ontario sites (ELA and TLW) show negative SO₄ trends, one station at TLW and one in Quebec (MTM) are continuing to acidify. Longer data records are needed to verify acidification recovery.

A short paper summarizing the classification of regional nitrate concentrations in surface waters in an attempt to define areas of potential nitrogen based acidification. The seasonal cycle of nitrate extant at Turkey Lake is offered as evidence for developing nitrogen stauration. This paper uses information collected for and presented in 95-02.

Mass transfer coefficients of sulfur hexafluoride were measured in a linear gas transfer flume under different wind and wave conditions and compared to actual measurements made at Little Turkey Lake, TLW. Flux estimates of SF6 obtained from the flume were found to be in agreement with measured values.

The diets of four species of insectivorous ducks from small lakes in northeastern Ontario were examined. It was observed that lake acidification results in changes in the distribution of waterfowl broods and reproductive success, as prey is affected by changes in water chemistry.

Food chains in three acid-sensitive regions: Muskoka, Sudbury, and Algoma (including the TLW), were monitored to assess the effects of changing acid deposition on waterfowl and their prey. Abundance and distribution of benthic groups are related to pH, but the effect of fish in structuring the community must also be considered.

A model that estimates the effects of acid deposition on waterfowl was used to assess the responses to proposed reductions in SO₂ emissions in three regions of Ontario (including the TLW in Algoma). The greatest improvements were predicted to occur in the Sudbury region. Algoma should see moderate improvement, while the maximum proposed emission reduction will be needed just to maintain current conditions in Muskoka.

In order to assess the impact of acid rain control programs in the U.S. and Canada, long-term monitoring of aquatic ecosystem recovery has been conducted since 1987 by CWS in 3 regions of Ontario - Algoma (including the TLW), Muskoka and Sudbury, and in the Kejimkujik region of Nova Scotia. The breeding success of Common Loons which is monitored through the volunteer-based Canadian Lakes Loon Survey is also used as an indicator of the health of large oligotrophic lakes. Models (WARMS, RAISON/IAM) are being developed using all of this information to evaluate acid rain effects and to predict future changes and benefits of control strategies.

Evaluating the effects of N deposition is the main theme for this report. Section 1 summarizes monitoring activities; Section 2 gives background on impacts of N deposition in terrestrial ecosystems; and Section 3 presents an assessment of N processes, including input-output proton budgets for bulk deposition at 24 monitoring sites (including the TLW, the only North American site in this international program). Results from application of MAGIC, SAFE and SMART models are presented in Section 4, and Section 5 contains a summary and recommendations for future study.

Wet deposition precipitation chemistry from 1992. NAtChem contains information from both federal and provincial monitoring programs. TLW data are under Algoma. Spatial patterns and temporal variations as well as annual data summaries are presented.

Same as 95-13, but covering the 1993 calendar year.

The TLW is part of the DFO LRTAP biomonitoring program which includes 36 lakes and 21 rivers across eastern Canada considered to be sensitive to acidic deposition. This report characterizes fish and benthic communities in these areas, establishing a baseline for annual variability in species composition and abundance. Annual variability in acidic lakes is seen to be twice that of neutral lakes. Seasonal pH depression has deleterious effects on salmonid populations. Long-term monitoring is needed to identify trends, and to distinguish anthropogenic stress from natural variability.

The ForSVA model was used to assess the critical loads of S and N to 5 upland forest sites including the TLW. Al:Ca ratios in the soil leachates were also checked. Critical loads are less than or equal to present loadings.

In 1985, brook char were introduced into the lower basin of Batchawana Lake in the TLW, which had been fishless for more that 150 years. Growth rates peaked in the following year, and the production to biomass ratio stabilized in the third year. Food resources in the lake did not become depleted. Organisms serving as food for the fish population depend on seasonal energy, thus periodic rather than continuous stocking is a better strategy.

Using daily measurements from 5 CAPMoN monitoring sites in eastern Canada, data for AP (the acidifying potential of wet deposition), SO₄ and base cations were examined for trends during the period 1981-1993. At all sites the trend was downward for these parameters. At the Turkey Lakes Watershed (called Algoma) and Dorset sites, the trend was highly significant. Predictions about ecosystem response to SO₂ emissions must take into account changes in base cation concentrations.