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| Titel |
Dam tailwaters compound the effects of reservoirs on the longitudinal transport of organic carbon in an arid river |
| VerfasserIn |
A. J. Ulseth, R. O. Hall |
| 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 ; 12, no. 14 ; Nr. 12, no. 14 (2015-07-28), S.4345-4359 |
| Datensatznummer |
250118033
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| Publikation (Nr.) |
 copernicus.org/bg-12-4345-2015.pdf |
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| Zusammenfassung |
| Reservoirs on rivers can disrupt organic carbon (OC) transport and
transformation, but less is known how river reaches directly below dams
contribute to OC processing. We compared how reservoirs and their associated
tailwaters affected OC quantity and quality by calculating particulate
OC (POC) and dissolved OC (DOC) fluxes, and measuring composition and
bioavailability of DOC. We sampled the Yampa River near Maybell, Colorado,
USA, and the Green River above and below Fontenelle and Flaming Gorge
reservoirs as well as their respective tailwaters from early snowmelt to base flow
hydrological conditions. In unregulated reaches (Yampa River, Green River
above Fontenelle reservoir), DOC and POC concentrations increased with
snowmelt discharge. POC and DOC concentrations also increased with stream
discharge below Fontenelle reservoir, but there was no relationship between
DOC and stream flow below Flaming Gorge reservoir. The annual load of POC
was 3-fold lower below Fontenelle Reservoir and nearly 7-fold lower below
Flaming Gorge reservoir, compared to their respective upstream sampling
sites. DOC exported to downstream reaches from both reservoirs was less
bioavailable, as measured with bioassays, than DOC upriver of the
reservoirs. Lastly, tailwater reaches below the reservoirs generated OC,
exporting potentially 1.6–2.2 g C m−2 d−1 of OC to downstream
ecosystems. Therefore, the effect of impounding rivers on C fluxes is
greater than the impact of the reservoirs alone given the additive effect of
tailwater reaches below dams, which may produce and export comparable
amounts of likely autochthonous carbon to downstream reaches. |
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