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

ILCD Handbook: Framework and requirements for LCIA models and indicators First edition
ACIDIFICATION Check the following:
Overall evaluation of stakeholders acceptance criteria
Final recommendation
4.8 Eutrophication
4.8.1 Framework and scope
Threshold
(Minimum
score)
Importance
(H-N)
The impact category appears under different names like eutrophication, nutriphication or
nutrient enrichment. It addresses the impacts from the macro-nutrients nitrogen and
phosphorus in bio-available forms on aquatic and terrestrial ecosystems.
In natural terrestrial systems, the addition of nutrients may change the species
composition of the vegetation by favouring those species which benefit from higher levels of
nutrients to grow faster than more nutrient efficient plants. This therefore changes the plant
community from nutrient-poor (e.g. heath lands, dunes and raised bogs) to nutrient rich and
more commonly, due to the widespread dispersion of nutrients,, plant communities. The
primary impact on the plant community leads to secondary impacts on other species in the
terrestrial ecosystem. Terrestrial eutrophication is caused by deposition of airborne
emissions of nitrogen compounds like nitrogen oxides (NOx = NO and NO2) from combustion
processes and ammonia, NH3 from agriculture. Airborne spreading of phosphorus is not
prevalent, and terrestrial eutrophication is therefore mainly associated with nitrogen
compounds.
In aquatic systems, the addition of nutrients has a similar primary impact by fertilising the
plants (algae or macrophytes) with a number of consequences for the ecosystem:
Species composition of the plant community changes to more nutrient-demanding
species;
Algal blooms create shadowing, filtering the light penetrating into the water mass,
changing life conditions from the macrophytes, which need the light for photosynthesis,
and for predatory fish which need the light to see and catch their prey;
Oxygen depletion near the bottom of the water body where dead algae deposit and
degrade.
All these consequences lead to a change in the species composition and of the function of
the exposed aquatic ecosystem.
In aquatic systems it is often one of the macronutrients which limits the growth of algae.
Addition of the limiting nutrient will lead to increased primary production, while addition of the
nutrient which is not limiting will have no effect on the primary production, and this should be
reflected in the life cycle impact assessment. There may be seasonal variations in the pattern
of limiting nutrients, but as a general rule, P is the limiting nutrient in freshwater systems
while N is limiting nutrient in marine systems.
Freshwater and marine aquatic systems are exposed to water-borne emissions (nitrate,
other nitrogen compounds expressed as total N, phosphate and other phosphorus-containing
compounds expressed as total P). Marine aquatic systems and very large lakes are also
substantially exposed by airborne emissions (NOx).
4 Requirements for specific impact categories 61