Mapping of Critical Loads and Critical Load Exceedances in the Killarney Provincial Park, Ontario, Canada

Abstract

Calculations of critical loads for inputs of strong acids to lakes and exceedances of critical load can be a useful tool for the management of polluted areas. In Sudbury, Canada, large emissions of sulfur dioxide have resulted in widespread lake acidification in parts of northeastern Canada. Due to its vicinity to Sudbury, extensive lake acidification and fish loss has occurred in the Killarney Provincial Park. We have linked measured water quality to critical loads and strong acid deposition. Total S deposition decreased from an estimate of 70 meq m² yr¹ in 1981 to 47 meq m² yr¹ in 1997. The critical load was estimated to be exceeded in 57 % of the Killarney park area in 1981, whereas 38 % of the area was exceeded in 1997. A target load for total S deposition may be set at 30 meq m², corresponding to 14.4 kg SO4 ha¹ yr¹. This deposition level corresponds to a 2010-scenario according to the Clean Air Act Amendments with an additional 50 % emission reduction, and will protect the park area almost completely from exceedances of the critical load.