Biogeosciences, 14, 5003-5014, 2017
https://doi.org/10.5194/bg-14-5003-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
08 Nov 2017
Regional-scale lateral carbon transport and CO2 evasion in temperate stream catchments
Katrin Magin, Celia Somlai-Haase, Ralf B. Schäfer, and Andreas Lorke Institute for Environmental Sciences, University of Koblenz-Landau, Fortstr. 7, 76829 Landau, Germany
Abstract. Inland waters play an important role in regional to global-scale carbon cycling by transporting, processing and emitting substantial amounts of carbon, which originate mainly from their catchments. In this study, we analyzed the relationship between terrestrial net primary production (NPP) and the rate at which carbon is exported from the catchments in a temperate stream network. The analysis included more than 200 catchment areas in southwest Germany, ranging in size from 0.8 to 889 km2 for which CO2 evasion from stream surfaces and downstream transport with stream discharge were estimated from water quality monitoring data, while NPP in the catchments was obtained from a global data set based on remote sensing. We found that on average 13.9 g C m−2 yr−1 (corresponding to 2.7 % of terrestrial NPP) are exported from the catchments by streams and rivers, in which both CO2 evasion and downstream transport contributed about equally to this flux. The average carbon fluxes in the catchments of the study area resembled global and large-scale zonal mean values in many respects, including NPP, stream evasion and the carbon export per catchment area in the fluvial network. A review of existing studies on aquatic–terrestrial coupling in the carbon cycle suggests that the carbon export per catchment area varies in a relatively narrow range, despite a broad range of different spatial scales and hydrological characteristics of the study regions.

Citation: Magin, K., Somlai-Haase, C., Schäfer, R. B., and Lorke, A.: Regional-scale lateral carbon transport and CO2 evasion in temperate stream catchments, Biogeosciences, 14, 5003-5014, https://doi.org/10.5194/bg-14-5003-2017, 2017.
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We analyzed the relationship between terrestrial net primary production (NPP) and the rate at which carbon is exported from catchments in a temperate stream network. The carbon exported by streams and rivers corresponds to 2.7 % of the terrestrial NPP. CO2 evasion and downstream transport contribute about equally to this flux. A review of existing studies suggests that the catchment-specific carbon export varies in a relatively narrow range across different study regions and spatial scales.
We analyzed the relationship between terrestrial net primary production (NPP) and the rate at...
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