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| Titel |
Nitrate leaching from short-hydroperiod floodplain soils |
| VerfasserIn |
B. Huber, J. Luster, S. M. Bernasconi, J. Shrestha, E. Graf Pannatier |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 11 ; Nr. 9, no. 11 (2012-11-09), S.4385-4397 |
| Datensatznummer |
250007382
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| Publikation (Nr.) |
 copernicus.org/bg-9-4385-2012.pdf |
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| Zusammenfassung |
| Numerous studies have shown the importance of riparian zones to reduce
nitrate (NO3−) contamination coming from adjacent agricultural
land. Much less is known about nitrogen (N) transformations and nitrate
fluxes in riparian soils with short hydroperiods (1–3 days of inundation)
and there is no study that could show whether these soils are a N sink or
source.
Within a restored section of the Thur River in NE Switzerland, we measured
nitrate concentrations in soil solutions as an indicator of the net nitrate
production. Samples were collected along a quasi-successional gradient from
frequently inundated gravel bars to an alluvial forest, at three different
depths (10, 50 and 100 cm) over a one-year period. Along this gradient we
quantified N input (atmospheric deposition and sedimentation) and N output
(leaching) to create a nitrogen balance and assess the risk of nitrate
leaching from the unsaturated soil to the groundwater.
Overall, the main factor explaining the differences in nitrate
concentrations was the field capacity (FC). In subsoils with high FCs and
VWC near FC, high nitrate concentrations were observed, often exceeding the
Swiss and EU groundwater quality criterions of 400 and 800 μmol L−1, respectively. High sedimentation rates of river-derived nitrogen
led to apparent N retention up to 200 kg N ha−1 yr−1 in the
frequently inundated zones. By contrast, in the mature alluvial forest,
nitrate leaching exceeded total N input most of the time. As a result of the
large soil N pools, high amounts of nitrate were produced by nitrification
and up to 94 kg N-NO3− ha−1 yr−1 were leached into the
groundwater. Thus, during flooding when water fluxes are high, nitrate from
soils can contribute up to 11% to the total nitrate load in groundwater. |
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