Introduction
The emission of certain chemical compounds into the environment can cause lowering of pH (of lakes, forests, or agricultural soils) with serious and severe consequences for living organisms. The main cause is emissions from the combustion of fossil fuels and, in particular, sulfur-containing fuels.
The calculation model
To quantify this impact, standardization factors are used with the kg of equivalent SO2 as the reference unit through the acidification potential (AP - Acidification potential). The preliminary operation of this standardization consists in aggregating potentially acidic emissions (SO2, NOx) based on their tendency to form H+ ions. This tendency is often not spontaneous but requires intermediate chemical reactions assisted by the presence of catalysts (e.g., iron oxides, nitrogen oxides, or humidity), highlighting how, even in this case, the effects can add up and eventually amplify each other.
The acidification potential of a substance is defined as the ratio between the number of H+ ions per unit mass of the emitted substance and the number of H+ ions per unit mass of the substance SO2, chosen as the reference unit.
