The Incursion of Acid Deposition into Western North America

Abstract

Acidification processes in western North America will probably increase in scope and visibility over the foreseeable future. Localized acidification seems more probable for the next few decades than does a generalized acidified deposition over the western States. At least part of current acid deposition downwind of urban areas is associated with automobile emissions. However, increases in coal combustion for power generation might be expected to increase sulphur dioxide concentrations, along with several related acidifying agents. Interactions of air pollutants with orographic precipitation and snowmelt may bring some areas to public attention much earlier than others, depending upon site-specific matters of climate, topography, soils, water-bodies, and biota. Lakes and streams on windward slopes facing large urban or industrial sources of sulphur and nitrogen oxides may be most seriously at risk.