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Characterisation Method Information
Characterisation Method Name:
NOx impact on Wood
Date Completed:
Principal Method Name:
EPS: N-nutrification pathway and secondary particles pathway
Method Description:
Model 1, N-nutrification pathway

The characterisation factor is determined by a mechanistic method.

Nitrogen is a rate limiting factor for wood growth in a large part of the world.
About 40% of the land area in the temperate regions are covered with forests, and about
50% of the emissions of NOx are assumed to deposit on land areas. Most of the global
emissions are estimated to origin in temperate regions. Thus, from an average global emission of 1 kg of NOx, 0.2 deposits on temperate forests and contribute to increased growth, where N deficiency is growth limiting. If half of the N is used by the trees in the wood structure (ratio experienced when fertilising with calcium ammonium nitrate), if 10% of the forests have nitrogen deposition above the critical load, and if the wood consists of 1% N, (on dry basis), then 1 kg NOx will result in 0.4*0.5*0.5*0.9*14/46*100 =2.74 kg wood.

As the net effect is an increase of wood growth, we obtain a negative characterisation
factor, -2.74 kg wood/kg NOx.

Model 2, secondary particles pathway

The characterisation factor is determined by an equivalency method using PM10 as a reference.

As for Severe morbidity of EPS for NOx, the equivalency factor is 1.0.

The characterisation factor for PM10 was estimated to 0.00991 kg wood per kg PM10
giving a characterisation factor for NOx of 0.00991 kg wood per kg NOx.

For both pathways we get -2.74 +0.00991 = -2.73 kg wood/kg NOx.

Literature Reference:
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
Methodological Range:
The residence time in air in the order of a week and the residence time in soil is less than a year. The flow group is emissions anywhere on the globe during 1990. The environmental system investigated is therefore chosen to be global during 1990

Existing Characterisation Factors of NOx impact on Wood
Characterisation Parameter Category Indicator Impact Indication Principle Aspect Substance Quantity Unit Notes
CFactor Wood EPS/2000
Type = Emission
Direction = Output
Media = Air
Geography = *
NOx -2.73 kg/kg 2 pathways