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| Titel |
New insights into agricultural pesticide pollution through a complete and continuous pesticide screening during one growing season in five small Swiss streams |
| VerfasserIn |
Simon Mangold, Tobias Doppler, Simon Spycher, Miriam Langer, Marion Junghans, Manuel Kunz, Christian Stamm, Heinz Singer |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141944
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| Publikation (Nr.) |
 EGU/EGU2017-5504.pdf |
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| Zusammenfassung |
| Agricultural pesticides are regularly found in many surface waters draining agricultural areas.
Due to large fluctuations in concentration over time and the potentially high number of
pesticides, it is difficult to obtain a complete overview of the real pollution level. This
collaborative project between research, federal and cantonal authorities in Switzerland aimed
for a comprehensive assessment of pesticide pollution in five small agricultural streams to
tackle this knowledge gap. The five streams are located in catchments (1.5 to 9 km2) with
intensive agriculture covering a wide range of crops including vegetables, vineyards
and orchards. Twelve-hour composite samples were collected continuously from
March until the end of August 2015 with automatic sampling devices, yielding
360 samples per site. Using precipitation and water level data, we differentiated
between discharge events and low-flow periods. Samples from discharge events where
measured individually whereas samples taken during dry weather were pooled for the
analysis. This procedure resulted in a complete concentration profile over the entire
monitoring period covered by 34 - 60 samples per site. The analysis, using liquid
chromatography coupled to high resolution mass spectrometry involved a target screening
of about 220 pesticides. The measured concentrations were compared to chronic
and acute environmental quality standards (EQS values) resulting in risk quotients
RQs, which are the ratios between measured concentrations and the respective EQS
values.
Despite the small size of the catchments, we observed a large pesticide diversity in all of
them with 68 to 103 detected compounds per study area. At all sites, chronic EQS values
were exceeded. However, the exposure levels varied substantially among catchments.
Maximum chronic RQs per site ranged between 1.1 and 48.8 and the duration of EQS
exceedance varied between 2 weeks and 5.5 months. Additionally, the data reveal (very) high
concentration peaks reaching up to 40 μg L−1 for single active ingredients. Of
15 compounds measured at high concentrations, several measured concentrations
exceeded acute EQS values in three of the five areas for a duration of up to 2.5
months.
Concentration peaks were often linked to discharge events but not exclusively. These
findings demonstrate that rain driven processes were important causes of the observed
concentration levels but that additional (possibly point) sources need to be considered for a
comprehensive understanding of pesticide exposure. Overall, the results from these five
catchments provide an unique insight into the diversity of pesticide pollution of
small streams across a wide range of natural conditions in Switzerland. The spatial
differences indicate that the intensity of pesticide use alone cannot explain the level of
exposure but point to the influence of landscape characteristics such as topography, the
connectivity of field to the stream network or the number of connected farmyards. |
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