CALCULATION OF CRITICAL LOADS FOR ACID DEPOSITION
The critical load, defined as the maximum load of acid deposition that will not cause certain adverse effects, is calculated by using a mass balance for alkalinity for the catchment, forest soil or lake system considered. This simple method estimates the critical load from site characteristics such as mineral composition, bioremoval of base cations and the rate of solute transport through the system. Model calculations applied to Swedish soils showed that the methodology may be applied to any system provided that proper input data are available. For the most sensitive soils, the critical load is less than zero acidity, indicating that the forest growth is contributing to the acidification of very sensitive soils under the present forest managements methods.