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| Titel |
Land use effect and hydrological control on nitrate yield in subtropical mountainous watersheds |
| VerfasserIn |
J.-C. Huang, T.-Y. Lee, S.-J. Kao, S.-C. Hsu, H.-J. Lin, T.-R. Peng |
| 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. 3 ; Nr. 16, no. 3 (2012-03-06), S.699-714 |
| Datensatznummer |
250013205
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| Publikation (Nr.) |
 copernicus.org/hess-16-699-2012.pdf |
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| Zusammenfassung |
Nitrate export in small subtropical watersheds is rarely observed and the
estimation of individual land use nitrate yield from a mixed combination
within catchments has scarcely been studied. In this study the nitrate
concentrations at 16 nested catchments in the Chi-Chia-Wan watershed in
Central Taiwan were measured during 2007–2008. A 3-layer TOPMODEL was
applied to estimate daily discharge for ungauged sub-catchments. The
observed nitrate concentrations and the simulated discharges were used for
nitrate flux estimations through four flux methods. Meanwhile, a new
deconvolution computation was developed to resolve the nitrate yield of each
land use from within the mixed combinations.
The results showed that the observed mean NO3-N concentration in relatively
pristine catchments was approximately 0.145 ± 0.103 mg l−1, which is
comparable with other forestry catchments around the world. However, the
higher rainfall/runoff, substantial N deposition, and other nitrogen sources
resulted in significantly higher annual export of approximately 238–1018 kg-N km−2 yr−1.
Our deconvolution computation showed that the background
yield of natural forestry was ~351 ±62 kg-N km−2 yr−1. On the
other hand, the extremely high nitrate yield of active farmland was ~308,
170 ± 19 241 kg-N km−2 yr−1 due to over-fertilization. The
deconvolution computation technique is capable of tracing the mixed signals
at the outlet back to the nitrate productions from varied land use patterns.
It advances the application of river monitoring network. The typical values
of nitrate yields can serve as a guideline for land management. Comparing
the nitrogen input and output, we found some nitrogen missing in the cycling
which may indicate certain removal processes and we therefore suggest
further study to be carried out to fully understand nitrogen cycling in
subtropics. |
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