|Characterisation Method Name:|
|SO2 impact on base cat-ion capacity|
|Principal Method Name:|
|EPS: acidification pathway|
The characterisation factor is determined by a mechanistic method.
When sulphur dioxide is oxidised in air, two protons (H + ) are produced per mole of SO2.
When the oxidised S in form of sulphate is deposited on soil, the protons will substitute base cat-ions, e.g Mg ++ or K + , which are important nutrient to plants.
Portion of emitted substance that will reach target
On a global scale the critical load for soil acidification is exceeded on approximately 10% of the land area. As much of the SO2 sources are located near the sea, part of the emissions is deposited in the oceans and in inland water. As the average residence time is in the order of a week and the corresponding air transport of several 1000 km, it is reasonable to assume that 50% of the S is deposited at land. This means that approximately 5% of the SO2 cause base cat-ion depletion.
Calculation of characterisation factor
For each kg of SO2 there is thus 2*1000*0.05/64 = 1.56 equivalents of base cat-ions reserves depleted.
|Steen B (1999b): A systematic approach to environmental priority strategies in product development (EPS). Version 2000 – Models and data of the default method CPM report Chalmers University of Technology Sweden|
|The system is global and the time period is 1990.|
|Characterisation Parameter||Category Indicator||Impact Indication Principle||Aspect||Substance||Quantity||Unit||Notes|
|CFactor||Base cat-ion capacity||EPS/2000||
|SO2||1.56||H+ mole equivalence/kg||acidification pathway|