The Acidic Precipitation in Ontario Study (A.P.I.O.S.)

Anticipated effects of soil acidification include: reduced pH, leaching of basic cations (such as magnesium and calcium) and other exchangeable plant nutrients, reduction in base saturation and cation-exchange capacity, mobilization of soil-bound metals such as aluminum, and changes in biological activity such as decreased nitrification and soil respiration. The principal objective of the baseline program is to establish a uniform data base for soils across the province.

This data base

• provides current data to identify future trends,
• enables the development of laboratory experiments which define soil sensitivity criteria to acidic precipitation, and
• provides information required for sensitivity mapping of soils throughout Ontario.