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Titel |
Interacting effects of climate and agriculture on fluvial DOM in temperate and subtropical catchments |
VerfasserIn |
D. Graeber, G. Goyenola, M. Meerhoff, E. Zwirnmann, N. B. Ovesen, M. Glendell, J. Gelbrecht, F. Teixeira de Mello, I. González-Bergonzoni, E. Jeppesen, Brian Kronvang |
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 ; 19, no. 5 ; Nr. 19, no. 5 (2015-05-20), S.2377-2394 |
Datensatznummer |
250120716
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Publikation (Nr.) |
copernicus.org/hess-19-2377-2015.pdf |
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Zusammenfassung |
Dissolved organic matter (DOM) is an important factor in aquatic ecosystems,
which is involved in a large variety of biogeochemical and ecological
processes, and recent literature suggests that it could be strongly affected
by agriculture in different climates. Based on novel monitoring techniques,
we investigated the interaction of climate and agriculture effects on DOM
quantity and quality. To examine this, we took water samples over 2 years
in two paired intensive and extensive farming catchments in each of Denmark
(temperate climate) and Uruguay (subtropical climate). We measured dissolved
organic carbon (DOC) and nitrogen (DON) concentrations and DOC and DON
molecular fractions with size-exclusion chromatography. Moreover, we
characterized DOM quality with absorbance and fluorescence measurements, as
well as parallel factor analysis (PARAFAC). We also calculated the DOC and
DON loads based on daily discharge measurements, as well as measured
precipitation and air temperature. The fluvial DOM in the catchments in
Uruguay was characterized by higher temporal variability of DOC and DON loads
which were clearly to a higher temporal variability of precipitation and a
DOM composition with rather plant-like character relative to the Danish
catchments. Moreover, we found a consistently higher temporal variability of
DOC and DON loads in the intensive farming catchments than in the extensive
farming catchments, with highest temporal variability in the Uruguayan
intensive farming catchment. Furthermore, the composition of DOM exported
from the intensive farming catchments was consistently complex and always
related to microbial processing in both Denmark and Uruguay. This was
indicated by low C : N ratios, several spectroscopic DOM composition indices
and PARAFAC fluorescence components. We propose that the consistent effect of
intensive farming on DOM composition and the temporal variability of DOC and
DON loads is related to similarities in the management of agriculture, which
may have widescale implications for fluvial DOM composition, as well as
related ecological processes and biogeochemical cycles. |
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