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| Titel |
Warming increases carbon and nutrient fluxes from sediments in streams across land use |
| VerfasserIn |
S.-W. Duan, S. S. Kaushal |
| 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 ; 10, no. 2 ; Nr. 10, no. 2 (2013-02-25), S.1193-1207 |
| Datensatznummer |
250018116
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| Publikation (Nr.) |
 copernicus.org/bg-10-1193-2013.pdf |
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| Zusammenfassung |
| Rising water temperatures due to climate and land use change can accelerate
biogeochemical fluxes from sediments to streams. We investigated impacts of
increased streamwater temperatures on sediment fluxes of dissolved organic
carbon (DOC), nitrate, soluble reactive phosphorus (SRP) and sulfate.
Experiments were conducted at 8 long-term monitoring sites across land use
(forest, agricultural, suburban, and urban) at the Baltimore Ecosystem Study
Long-Term Ecological Research (LTER) site in the Chesapeake Bay watershed.
Over 20 yr of routine water temperature data showed substantial variation
across seasons and years. Lab incubations of sediment and overlying water
were conducted at 4 temperatures (4 °C, 15 °C,
25 °C, and 35 °C) for 48 h. Results indicated: (1) warming
significantly increased sediment DOC fluxes to overlying water across land
use but decreased DOC quality via increases in the humic-like to protein-like
fractions, (2) warming consistently increased SRP fluxes from sediments to
overlying water across land use, (3) warming increased sulfate fluxes from
sediments to overlying water at rural/suburban sites but decreased sulfate
fluxes at some urban sites likely due to sulfate reduction, and (4) nitrate
fluxes showed an increasing trend with temperature at some forest and urban
sites but with larger variability than SRP. Sediment fluxes of nitrate, SRP
and sulfate were strongly related to watershed urbanization and organic
matter content. Using relationships of sediment fluxes with temperature, we
estimate a 5 °C warming would increase mean sediment fluxes of SRP,
DOC and nitrate-N across streams by 0.27–1.37 g m−2 yr−1,
0.03–0.14 kg m−2 yr−1, and
0.001–0.06 kg m−2 yr−1. Understanding warming impacts on
coupled biogeochemical cycles in streams (e.g., organic matter
mineralization, P sorption, nitrification, denitrification, and sulfate
reduction) is critical for forecasting shifts in carbon and nutrient loads in
response to interactive impacts of climate and land use change. |
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