Acidification: kg sulphur dioxide (SO2) eq.
Acidic gases such as sulphur dioxide (SO2) react with water in the atmosphere to form “acid rain”, a process known as acid deposition. When this rain falls, often a considerable distance from the original source of the gas, it causes ecosystem impairment of varying degree, depending upon the nature of the landscape ecosystems. Gases that cause acid deposition include ammonia, nitrogen oxides and sulphur oxides.
Acidification potential is expressed using the reference unit, kg SO2 equivalent. The model does not take account of regional differences in terms of which areas are more or less susceptible to acidification. It accounts only for acidification caused by SO2 and NOx. This includes acidification due to fertiliser use, according to the method developed by the Intergovernmental Panel on Climate Change (IPCC). CML have based the characterisation factor on the RAINS model developed by the University of Amsterdam.