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| Titel |
Effect on nitrate concentration in stream water of agricultural practices in small catchments in Brittany: I. Annual nitrogen budgets |
| VerfasserIn |
L. Ruiz, S. Abiven, P. Durand, C. Martin, F. Vertès, V. Beaujouan |
| 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 ; 6, no. 3 ; Nr. 6, no. 3, S.497-506 |
| Datensatznummer |
250003566
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| Publikation (Nr.) |
 copernicus.org/hess-6-497-2002.pdf |
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| Zusammenfassung |
| The
hydrological and biogeochemical monitoring of catchments has become a common
approach for studying the effect of the evolution of agricultural practices on
water resources. In numerous studies, the catchment is used as a “mega-lysimeter�?
to calculate annual input-output budgets. However, the literature reflects two
opposite interpretations of the trends of nitrate concentration in streamwater.
For some authors, essentially in applied studies, the mean residence time of
leached nitrate in shallow groundwater systems is much less than one year and
river loads reflect annual land use while for others, nitrate is essentially
transport limited, independent of soil nitrate supply in the short term and
annual variations reflect changes in climatic conditions. This study tests the
effect of agricultural land-use changes on inter-annual nitrate trends on stream
water of six small adjacent catchments from 0.10 to 0.57 km2 in area, on
granite bedrock, at Kerbernez, in Western Brittany (France). Nitrate
concentrations and loads in streamwater have been monitored for nine years (1992
to 2000) at the outlet of the catchments. An extensive survey of agricultural
practices from 1993 to 1999 allowed assessment of the nitrogen available for
leaching through nitrogen budgets. For such small catchments, year-to-year
variations of nitrate leaching can be very important, even when considering the
‘memory effect’ of soil, while nitrate concentrations in streamwater appear
relatively steady. No correlation was found between the calculated mean nitrate
concentration of drainage water and the mean annual concentration in streams,
which can even exhibit opposite trends in inter-annual variations. The climatic
conditions do not affect the mean concentration in streamwater significantly.
These results suggest that groundwater plays an important role in the control of
streamwater nitrate concentration.
Keywords: nitrate, diffuse pollution, agricultural catchment, nitrogen budget,
leaching, Kerbernez catchments |
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