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Title:
Secondary Spatial range of Transformation products:
A New Proxy Measure for the Spatial Extent of the
Overall Chemical Impact of a Pollutant
Abstract
The release of a chemical in the environment may cause adverse
effects. These effects result from the exposure to the chemical
released, but also from the exposure to its transformation products.
Accordingly, the direct impact is defined here as the sum of
the effects caused by the chemical released, whereas the overall
impact is the sum of the effects caused by the chemical released
and its transformation products. In the first part of this work,
the status of transformation products in the current practice
of chemical assessment is briefly reviewed, with the legislation
of the European Union (Directives 67/548/EEC, 93/67/EEC, 91/414/EEC
and Regulation1488/98) taken as representative example. As it
turns out, relevant transformation products of pesticides must
be assessed at the same level as their precursors, but transformation
products of non-pesticides are usually not assessed at all. In
the second part, it is shown that transformation products can
be perfectly integrated in an assessment based on spatial range.
The spatial range of a chemical is a proxy measure of the spatial
extent of its impact. This concept was proposed by Scheringer,
Berg and Müller-Herold. So far, only the spatial extent
of the direct impact has been estimated, and the corresponding
spatial range was called characteristic spatial range. The goal
of this thesis is to estimate the spatial extent of the overall
impact. The approach chosen is based on the analytic method developed
by Müller-Herold and Nickel for the calculation of characteristic
spatial range. The model framework covers global long-range transport
and first-order reactions. The result obtained is a closed formula
for secondary spatial range, expressed as a function of the respective
characteristic ranges of a precursor and its first-generation
transformation product. Secondary spatial range is interpreted
as a proxy measure of the spatial extent of the overall impact.
You can download the
whole dissertation (1.3MB) or only the summary , in English
or in French,
as PDF-files.
The main results of this dissertation will appear in a forthcoming
issue of Ecological Modelling (see abstract).
An excel spreadsheet for the calculation of characteristic
and secondary spatial range can be downloaded here.
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