Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 10, issue 2
Biogeosciences, 10, 1193–1207, 2013
https://doi.org/10.5194/bg-10-1193-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 10, 1193–1207, 2013
https://doi.org/10.5194/bg-10-1193-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 25 Feb 2013

Research article | 25 Feb 2013

Warming increases carbon and nutrient fluxes from sediments in streams across land use

S.-W. Duan and S. S. Kaushal S.-W. Duan and S. S. Kaushal
  • Department of Geology and Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, 20742, USA

Abstract. 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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