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| Titel |
Spatial variability of herbicide mobilisation and transport at catchment scale: insights from a field experiment |
| VerfasserIn |
T. Doppler, L. Camenzuli, G. Hirzel, M. Krauss, A. Lück, C. Stamm |
| 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 ; 16, no. 7 ; Nr. 16, no. 7 (2012-07-06), S.1947-1967 |
| Datensatznummer |
250013358
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| Publikation (Nr.) |
 copernicus.org/hess-16-1947-2012.pdf |
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| Zusammenfassung |
During rain events, herbicides can be transported from their
point of application to surface waters, where they may harm
aquatic organisms. Since the spatial pattern of mobilisation
and transport is heterogeneous, the contributions of different
fields to the herbicide load in the stream may vary
considerably within one catchment. Therefore, the prediction
of contributing areas could help to target mitigation measures
efficiently to those locations where they reduce herbicide
pollution the most.
Such spatial predictions require sufficient insight into the
underlying transport processes. To improve the understanding
of the process chain of herbicide mobilisation on the field
and the subsequent transport through the catchment to the
stream, we performed a controlled herbicide application on
corn fields in a small agricultural catchment (ca.
1 km2) with intensive crop production in the Swiss
Plateau. Water
samples were collected at different locations in the catchment
(overland flow, tile drains and open channel) for two months after application in 2009, with a high
temporal resolution during rain events. We also analysed soil
samples from the experimental fields and measured discharge,
groundwater level, soil moisture and the occurrence of
overland flow at several locations. Several rain events with
varying intensities and magnitudes occurred during the study
period. Overland flow and erosion were frequently observed in
the entire catchment. Infiltration excess and saturation
excess overland flow were both observed. However, the main
herbicide loss event was dominated by infiltration
excess.
Despite the frequent and wide-spread occurrence of overland
flow, most of this water did not reach the
channel directly, but was retained in small depressions in the
catchment. From there, it reached the stream via macropores
and tile drains. Manholes of the drainage system and storm
drains for road and farmyard runoff acted as additional
shortcuts to the stream.
Although fast flow processes such as overland and macropore flow
reduce the influence of the herbicide's chemical properties on transport due to short
travel times, sorption properties influenced the herbicide
transfer from ponding overland flow to tile drains (macropore
flow). However, no influence of sorption was observed during
the mobilisation of the herbicides from soil to overland
flow. These observations on the role of herbicide
properties contradict previous
findings to some degree. Furthermore, they demonstrate that valuable insight can be gained
by making spatially detailed observations along the flow paths. |
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