Critical Load Assessments and Dynamic Model Applications for Lakes in North America

Abstract

Critical loads were first discussed by Canada and the United States during the early 1980s in the Memorandum of Intent on Transboundary Air Pollutionthe earliest bilateral acid rain assessment. A legacy of this assessment is the specification of critical loads of acidity for surface waters in Canada. This chapter reviews the application of steady-state and dynamic models to assess the impacts of acidic deposition on surface waters in North America. It describes the historic development of critical loads in Canada and the United States, and provides a broad overview of wide-scale regional applications of steady-state and dynamic models. Furthermore, the chapter presents a national application of the First-order Acidity Balance (FAB) model for surface waters in Canada, with reference to similar assessments in Europe.