Page 283 - Materials Chemistry, Second Edition

4.5 Impact Categories, Impact Indicators and Characterisation Factors 267

agriculture, the connection between the technosphere and environment is close
and the necessary distinction is often delicate.
4.5.2.6.3 Characterisation/Quantification By simply equating the EP and the
phosphate equivalents according to Table 4.14 the following is valid:

EP = ∑ (m × EP ) (kg PO 4 3– -equivalents) (4.23)
i
i
i
where m = load of the substance i contributing to eutrophication per fU.
i
4.5.2.6.4 Terrestrial Eutrophication The characterisation according to
Equation 4.23 does not differentiate between aquatic and terrestrial eutrophication
and therefore represents the simplest method. The advantage of clarity of this
computation is a result of strong simplifications on the impact side. Therefore,
attempts have been made to sacrifice part of the simplicity for an approach to reality,
for example, by the ‘Nordic Guidelines’. 261) A division of the impact category into
aquatic and terrestrial seems to be the most promising. 262) As most emissions into
the inland air are deposited on soils, emissions into air of compounds containing N
mostly as NO and NH are the most important input to the soil and can therefore
x 3
be assigned to terrestrial eutrophication. For water bodies relevant emissions into
water (phosphate, ammonium, COD/BOD, etc.) should be considered.
If this division is made, the EP of the soil nutrients are often expressed as
nitrate equivalents (EP nitrate = 1). This formal conversion merely serves as a
better distinctness and indicates the fundamental contribution of nitrate as the
most frequent limiting element in soil. Phosphate however can also be used as
reference.
For a calculation of terrestrial eutrophication only emissions to air with an over-
fertilising impact are considered. For a separate assessment of this subcategory,
the eutrophication of water is quantified only by emissions into water including
COD. For the classification step in impact assessment this has to be kept in
mind! According to Table 4.14 mainly the nitrogen oxides NO, NO and their sum
2
NO (calculated as NO ) are considered for terrestrial eutrophication calculation.
x 2
Ammonia (NH ) is also part of terrestrial eutrophicating emissions into the air,
3
but in the air is quickly transformed into NO or in water into the ammonium
x
+
ion (NH ). The amount of nitrogen that reaches surface-near air by way of NH 3
4
should not, however, be neglected.
Characterisation of terrestrial eutrophication is also calculated according to
Equation 4.23 but separately assigned.
4.5.2.6.5 Regionalisation A discussion of regionalisation is closely linked to the
discussion of the impact categories ‘formation of photo oxidants (summer smog)’
and ‘acidification’. The basic set of problems remains the same. Transport by air can
in principle be calculated with identical models (RAINS, EMEP, etc.). Transport
by water abides to different rules. The most important entry of fertilisers into

261) Lindfors et al. (1994, 1995), Finnveden and Potting (2001) and Guin´ ee et al. (2002).
262) Lindfors et al. (1994, 1995) and Udo de Haes (1996).