Regional-scale lateral carbon transport and CO2 evasion in temperate stream catchments

Katrin Magin, Celia Somlai-Haase, Ralf B. Schäfer, Andreas Lorke
2017 Biogeosciences Discussions  
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
more » ... km<sup>2</sup> for which CO<sub>2</sub> 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 2.7&amp;thinsp;% of terrestrial NPP (13.9&amp;thinsp;g&amp;thinsp;C&amp;thinsp;m<sup>2</sup>&amp;thinsp;yr<sup>&amp;minus;1</sup>) are exported from the catchments by streams and rivers, in which both CO<sub>2</sub> 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 as well as the catchment-specific total export rate of carbon in the fluvial network. A review of existing studies on aquatic-terrestrial coupling in the carbon cycle suggests that the catchment-specific carbon export varies in a relatively narrow range, despite a broad range of different spatial scales and hydrological characteristics of the study regions.
doi:10.5194/bg-2017-16 fatcat:mspholzgtrbjrim7msjtpbwsci