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| Titel |
Model-based estimation of pesticides and transformation products and their export pathways in a headwater catchment |
| VerfasserIn |
M. Gaßmann, C. Stamm, O. Olsson, J. Lange, K. Kümmerer, M. Weiler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 12 ; Nr. 17, no. 12 (2013-12-23), S.5213-5228 |
| Datensatznummer |
250086040
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| Publikation (Nr.) |
 copernicus.org/hess-17-5213-2013.pdf |
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| Zusammenfassung |
| Pesticides applied onto agricultural fields are frequently found in adjacent
rivers. To what extent and along which pathways they are transported is
influenced by intrinsic pesticide properties such as sorption and
degradation. In the environment, incomplete degradation of pesticides leads
to the formation of transformation products (TPs), which may differ from the
parent compounds regarding their intrinsic fate characteristics. Thus, the
export processes of TPs in catchments and streams may also be different. In
order to test this hypothesis, we extended a distributed hydrological model
by the fate and behaviour of pesticides and transformation products and
applied it to a small, well-monitored headwater catchment in Switzerland.
The successful model evaluation of three pesticides and their TPs at three
sampling locations in the catchment enabled us to estimate the quantity of
contributing processes for pollutant export. Since all TPs were more mobile
than their parent compounds (PCs), they exhibited larger fractions of export
via subsurface pathways. However, besides freshly applied pesticides,
subsurface export was found to be influenced by residues of former
applications. Export along preferential flow pathways was less dependent on
substance fate characteristics than soil matrix export, but total soil water
flow to tile drains increased more due to preferential flow for stronger
sorbing substances. Our results indicate that runoff generation by matrix
flow to tile drains gained importance towards the end of the modelling
period whereas the contributions from fast surface runoff and preferential
flow decreased. Accordingly, TPs were to a large extent exported under
different hydrological conditions than their PCs, due to their delayed
formation and longer half-lives. Thus, not only their different intrinsic
characteristics but also their delayed formation could be responsible for
the fact that TPs generally took different pathways than their PCs. We
suggest that these results should be considered in risk assessment for the
export of agricultural chemicals to adjacent rivers and that models should
be extended to include both PCs and TPs. |
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