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| Titel |
Source identification of nitrate by means of isotopic tracers in the Baltic Sea catchments |
| VerfasserIn |
M. Voss, B. Deutsch, R. Elmgren, C. Humborg, P. Kuuppo, M. Pastuszak, C. Rolff, U. Schulte |
| 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 ; 3, no. 4 ; Nr. 3, no. 4 (2006-12-20), S.663-676 |
| Datensatznummer |
250001172
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| Publikation (Nr.) |
 copernicus.org/bg-3-663-2006.pdf |
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| Zusammenfassung |
| Nitrate input to a river is largely controlled by land use in its catchment.
We compared the information carried by the isotopic signatures of nitrate in
12 Baltic rivers, in relation to the vegetation cover, land use, and
fertilization of agricultural land of their catchments. We found isotope
values in nitrate ranging from −2 to 14‰ for δ15N and 8 to
25‰ for δ18O. The annual variability of riverine nitrate isotope
signatures is presented in detail for one Nordic, the Kemijoki, and two
southern rivers, the Vistula and Oder. Nordic rivers with relatively
pristine vegetation in their catchments show not only low δ15N
values and high δ18O-NO3− but also lower annual
variability than rivers draining densely populated land. Seasonal signals
were found in all the rivers. We used load weighted nitrate isotope data and
data from the three major N sources (farmland/sewage, atmospheric deposition
and from runoff of pristine soils) to theoretically estimate the shares of
nitrate from these sources. The results of an isotope mixing model (IMM-1)
agree reasonably well with the same estimates for agricultural land derived
from a Global Land Cover (GLC) data base, with a deviation varying from
−16% to +26%. The comparison with an emission model (EM) reveals
relatively good agreements for intensively used catchments (−18 to +18%
deviation). Rather unsatisfactory agreement was found between the IMM-1 and
GLC calculations for pristine catchments (−36 to +50% deviation).
Advantages and limitations of the tested model are discussed. |
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