ILCD Handbook: Framework and requirements for LCIA models and ...

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ILCD Handbook: Framework and requirements for LCIA models and indicators First edition One of the consequences of eutrophication is oxygen depletion near the bottom of the exposed systems. Emissions of biological material may also contribute to oxygen depletion when it degrades in the water. This is why some characterisation models provide characterisation factors for waterborne emissions of organic material, expressed as: BOD: Biological Oxygen Demand when degraded biologically in water, typically over 5 or 7 days. COD: Chemical Oxygen Demand when degraded by chemical oxidation. 4 Requirements for specific impact categories 62 or The inclusion of COD and BOD emissions is not consistent with the impact pathway at midpoint level, but they do contribute to some of the same damages, as emission of nutrients (see Figure 4-11). The model framework for the eutrophication characterization factor is expressed as a fate factor: FF multiplied by an effect factor: EF as per equation below: CFi,m,r = FF·EF = fi,mr ∙ βdose-response where: fi,m,r is the fate factor representing the transport of substance (i) in the media air or water (m) and the transfer to receiving environment (r). [dimensionless (kg/kg)]. βdose-response is the effect factor expressing the response of the ecosystem to the change in nutrient status e.g. [Impact/kg N or P] or [-]. 4.8.1.1 Environmental Mechanism (cause-effect chain) Figure 4-11 shows the cause-effect chain for eutrophication of the aquatic and terrestrial environment from air and waterborne emissions of nutrients (N and P) and biological material (COD or BOD) with the most important pathways highlighted (bold arrows).
ILCD Handbook: Framework and requirements for LCIA models and indicators First edition Figure 4-11 Flow diagram for eutrophication 4.8.2 Criteria for Evaluation of this impact category Following the general criteria described in Chapter 2, the main criteria ‗Environmental relevance‘ and ‗scientific robustness‘ have been specified by the following sub criteria: Fate and transport is considered. Advection out of a region is not considered a final loss. Influential fate processes are considered: - For aquatic systems: denitrification, precipitation and sedimentation of P - For terrestrial systems: oxidation, deposition. For damages on ecosystems, a fate sensitivity factor discriminating between sensitive and insensitive recipients is included: - For aquatic systems according to their sensitivity to eutrophication and oxygen depletion and limiting nutrient (N for marine, P for freshwater). - For terrestrial systems according to the sensitivity to eutrophication (critical load, N). Magnitude of exceedance for exposure above critical level is considered. Potency or dose-response is included. Distinction of individual N- and P-compounds. The model reflects the latest knowledge for the cause-effect chain (the critical links are covered) - Atmospheric fate and transport model 4 Requirements for specific impact categories 63
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