The role of atmospheric dispersion models and ecosystem sensitivity in the determination of characterisation factors for acidifying and eutrophying emissions in LCIA |
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Authors: | Maximilian Posch Jyri Seppälä Jean-Paul Hettelingh Matti Johansson Manuele Margni Olivier Jolliet |
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Institution: | 1.Coordination Centre for Effects (CCE), PBL,Bilthoven,The Netherlands;2.Finnish Environment Institute (SYKE),Helsinki,Finland;3.United Nations Economic Commission for Europe,Palais des Nations,Geneva 10,Switzerland;4.CIRAIG, Ecole Polytechnique de Montréal,Ecole Polytechnique de Montreal,Montréal,Canada;5.Center for Risk Science and Communication, Department of Environmental Health Sciences, School of Public Health,University of Michigan,Ann Arbor,USA |
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Abstract: | Background, aim and scope The methodological choices and framework to assess environmental impacts in life cycle assessment are still under discussion.
Despite intensive developments worldwide, few attempts have been made hitherto to systematically present the role of different
factors of characterisation models in life cycle impact assessment (LCIA). The aim of this study is to show how European average
and country-dependent characterisation factors for acidifying and eutrophying emissions differ when using (a) acidifying and
eutrophying potentials alone, (b) depositions from an atmospheric dispersion model or (c) critical loads in conjunction with
those depositions. Furthermore, in the latter case, the contributions of emissions, an atmospheric transport model and critical
loads to changes in characterisation factors of NO2 are studied. In addition, the new characterisation factors based on the accumulated exceedance (AE) method are presented
using updated emissions, a new atmospheric transport model and the latest critical loads.
Materials and methods In this study, characterisation factors for acidifying and eutrophying emissions are calculated by three different methods.
In the ‘no fate’ (NF) methods, acidifying and eutrophying potentials alone are considered as characterisation factors. In
the ‘only above terrestrial environment’ (OT) approach, characterisation factors are based on the deposition of the acidifying
or eutrophying substances to terrestrial land surfaces. The third method is the so-called AE method in which critical loads
are used in conjunction with depositions. The results of the methods are compared both at the European and the country level
using weighted mean, weighted standard deviation, minimum and maximum values. To illustrate the sensitivity of the AE method,
changes in European emissions, employed atmospheric dispersion model and the critical loads database are conducted step-by-step,
and the differences between the results are analysed.
Results and discussion For European average characterisation factors, the three characterisation methods of acidification produce results in which
the contributions of NH3, NO2 and SO2 to the acidification indicator do not differ much within each method when 1 kg of each acidifying substance is emitted. However,
the NF methods cannot describe any spatial aspects of environmental problems. Both OT and AE methods show that the spatial
aspects play an important role in the characterisation factors. The AE method results in greater differentiations between
country-dependent characterisation factors than does the OT method. In addition, the results of the AE and OT methods differ
from each other for individual countries. A major shortcoming of the OT approach is that it does not consider the sensitivity
of the ecosystems onto which the pollutants are deposited, whereas the AE approach does. In the case of the AE method, a new
atmospheric dispersion model, new information on emissions and critical loads have a different influence on the characterisation
factors, depending on the country. The results of statistics show that the change in the atmospheric dispersion model has
a greatest influence on the results, since ecosystem-specific depositions are taken into account for the first time.
Conclusions and recommendations The simple NF methods can be used in a first approximation to assess the impacts of acidification and terrestrial eutrophication
in cases where we do not know where the emissions occur. The OT approach is a more advanced method compared with the NF method,
but its capability to describe spatial aspects is limited. The AE factors are truly impact-oriented characterisation factors
and the information used here represents the current best knowledge about the assessment practice of acidification and terrestrial
eutrophication in Europe. The key message of this study is that there is no shortcut to achieving advanced characterisation
of acidification and terrestrial eutrophication: an advanced methodology cannot develop without atmospheric dispersion models
and information on ecosystem sensitivity. |
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Keywords: | Acidification Atmospheric transport Characterisation Critical loads Europe LCIA Life cycle impact assessment Terrestrial eutrophication |
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