pH and hydrogen ion deposition patterns in precipitation for the continental United States and Canada

Maps of both volume-weighted mean pH and mean H⁺ deposition in precipitation were developed for the continental United States and Canada using data from 12 precipitation chemistry monitoring networks. The maps were constructed using 1981–1982 laboratory pH data from approximately 130 monitoring sites. The area of greatest acidity (lowest pH/highest H⁺ deposition) is located in the northern Ohio Valley and southeastern Ontario, an area corresponding to high SO_x and NO_x emissions.