Page 224 - Materials Chemistry, Second Edition

208 4 Life Cycle Impact Assessment

Example 1: Climate change (greenhouse effect) 73)

Primary impact: Increased radiation absorption by molecules of the atmosphere
within the infrared (IR) window of approximately 10–15 μm (radiative forc-
ing).
Secondary impact: Increase in the average temperature of the troposphere.
Tertiary impact: Melting of glaciers and arctic ice, climate instabilities, shift
of climate zones, rise of the Sea level, spreading of diseases, changes in
ecosystems, and so on.
It is important to note that while the primary effect is a well measurable phe-
nomenon, the secondary impact can be more or less adequately described by
the atmospheric life time of the GHGs including scenario-like assumptions, but
tertiary effects can only be poorly quantified. The lesson to be learned is that GHGs
that were quantified in the inventory have to be as closely correlated to primary
and secondary effects as possible, and not to the far more uncertain tertiary effects.
These are the basics of the so-called midpoint-method.

Example 2: Acidification

Primary impact: Deposition of airborne acids on lakes, (bare) soil, trees (leaves,
roots, etc.) and other vegetation.
Secondary impact: Change of pH value in case of insufficient buffering.
Tertiary impacts: Fish mortality by acid or by the release of Al 3+ ions; contribution
to the ‘new type of forest damage’, damage to the vegetation by mineral
+
+
2+
depletion of the soils (e.g. Na ,K and Mg ), contamination of groundwater
by (re)mobilised heavy metals, and so on. Change of aquatic and terrestrial
ecosystems.
The position of the (mid-point) indicator is chosen as ‘closest possible to releases’.
Subsequent quantification is done by stoichiometric conversion of inventory items
+
to the mass of protons set free (H ) or the equivalent mass of SO as anhydride
2
of sulphurous acid (H SO ) and precursor to sulphuric acid (H SO )inthe
2 3 2 4
atmosphere. Equivalence factors can clearly be determined from the chemical
+
formulas unambiguously. The different quantifications proposed (H or SO -
2
equivalents) have identical validity, they merely differ by numerical values. Other
possibilities of quantification and regionalisation are introduced in Section 4.5.2.5.

73) IPCC (1990, 1992, 1995a,b,c, 1996a,b, 2001, 2007).