Global Change Abstracts The Swiss Contribution - SCNAT

Global Change Abstracts – The Swiss Contribution | Oceans and Fresh Water Systems
hydrological soil information is not available at a
European scale, we reclassified the Soil Geographical
Database of Europe (SGDBE) at 1:1 million in a
hydrological manner by adopting the Hydrology Of
Soil Types (HOST) system developed in the UK. The
HOST classification describes dominant pathways
of water movement through soil and was related to
the base flow index (BFI) of a catchment (the longterm
proportion of base flow on total stream flow).
In the original UK study, a linear regression of the
coverage of HOST classes in a catchment explained
79% of BFI variability. We found that a hydrological
soil classification can be built based on the information
present in the SGDBE. The reclassified SGDBE
and the regression coefficients from the original UK
study were used to predict BFIs for 103 catchments
spread throughout Europe. The predicted BFI explained
around 65% of the variability in measured
BFI in catchments in Northern Europe, but the explained
variance decreased from North to South.
We therefore estimated new regression coefficients
from the European discharge data and found that
these were qualitatively similar to the original estimates
from the UK. This suggests little variation
across Europe in the hydrological effect of particular
HOST classes, but decreasing influence of soil
on BFI towards Southern Europe. Our preliminary
study showed that pedological information is useful
for characterising soil hydrology within Europe and
the long-term discharge regime of catchments in
Northern Europe. Based on these results, we draft a
roadmap for a refined hydrological classification of
European soils.
Hydrology and Earth System Sciences, 2007, V11,
N4, pp 1501-1513.
08.1-278
Selecting scenarios to assess exposure of surface
waters to veterinary medicines in Europe
Schneider M K, Stamm C, Fenner K
Switzerland
Water Resources , Agriculture, Soil Sciences
Registering a veterinary medicinal product (VMP) in
the European Union requires assessing its potential
to contaminate surface waters (SW) on a European
scale. VMP are spread to land in manure or excreted
during grazing and may enter SW through runoff,
erosion, or leaching. Since the factors driving these
processes vary largely across Europe, it is necessary
to identify characteristic conditions, so-called scenarios,
un(er which VMP enter SW. These scenarios
may guide the parameterization of mechanistic fate
models to predict environmental concentrations for
environmental risk assessment. A number of such
scenarios for pesticides and VMP have been developed
rather pragmatically. Here, we describe how a
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geo-referenced European database of driving factors
was used to divide the European environment into
groups with similar conditions for SW contamination
by VMP. Out of these groups, relevant exposure
scenarios in Europe were selected by a simple scoring
system. Comparing these to the existing scenarios
showed that a number of situations are not well
covered. The newly identified scenarios are primarily
located in hilly areas of Central Europe and the
Mediterranean, and in Eastern European plains with
a continental climate. We recommend that they are
included in the technical guidelines for higher-tier
assessment of VMP.
Environmental Science Technology, 2007, V41,
N13, JUL 1, pp 4669-4676.
08.1-279
Assessing iron-mediated oxidation of toluene
and reduction of nitroaromatic contaminants
in anoxic environments using compound- specific
isotope analysis
Tobler N B, Hofstetter T B, Schwarzenbach R P
Switzerland
Geochemistry & Geophysics , Microbiology , Marine
& Freshwater Biology
We evaluated compound-specific isotope analysis
(CSIA) as a tool to assess the coupling of microbial
toluene oxidation by Fe(III)- reducing
bacteria and abiotic reduction of nitroaromatic
contaminants by biogenic mineral-bound Fe(II)
species. Examination of the two processes in
isolated systems revealed a reproducible carbon
isotope fractionation for toluene oxidation by
Geobacter metallireducens with a solid Fe(111)
phase as terminal electron acceptor. We found a
carbon isotope enrichment factor, epsilon(C), of
-1.0 +/- 0.1%o, which corresponds to an apparent
kinetic isotope effect (AKIE(C)) of 1.0073 +/- 0.0009
for the oxidative cleavage of a C-H bond. Nitrogen
isotope fractionation of the reduction of nitroaromatic
compounds (NAC) by mineral-bound Fe(11)
species yielded a nitrogen isotope enrichment factor,
EN, of -39.7 +/- 3.4%o for the reduction of an
aromatic NO 2-group (AKIE(N) = 1.0413 +/- 0.0037)
that was constant for variable experimental conditions.
Finally, AKIE values for C and N observed
in coupled experiments, where reactive Fe(11) was
generated through microbial activity, were identical
to those obtained in the isolated experiments.
This study provides new evidence on isotope fractionation
behavior during contaminant transformation
and promotes the use of CSIA for-the elucidation
of complex contaminant transformation
pathways in the environment.
Environmental Science Technology, 2007, V41,
N22, NOV 15, pp 7773-7780.