A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters

• Published in: Die Naturwissenschaften Vol. 105; no. 3-4; pp. 25 - 9
• Main Authors: Engel, Fabian, Farrell, Kaitlin J., McCullough, Ian M., Scordo, Facundo, Denfeld, Blaize A., Dugan, Hilary A., de Eyto, Elvira, Hanson, Paul C., McClure, Ryan P., Nõges, Peeter, Nõges, Tiina, Ryder, Elizabeth, Weathers, Kathleen C., Weyhenmeyer, Gesa A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2018; Springer Nature B.V
• Subjects: Activated carbon; Aquatic ecosystems; Biomedical and Life Sciences; Carbon - chemistry; Carbon cycle; Carbon dioxide; Carbon sources; Classification; Climate change; Concepts & Synthesis; Dissolved inorganic carbon; earth system dels; Earth system models; Ecology - methods; Ecosystem; Environment; Environmental changes; Exports; Global carbon cycle; Hydrologic CO2 transport; Inland waters; Lake carbon cycling; Lake classification; Lake functioning; Lake primary production; Lakes; Lakes - chemistry; Life Sciences; Mineralization; Models, Theoretical; Open channels; Primary production; Rainfall; Terrestrial ecosystems; Terrestrial environments; Earth system models; Lake primary production; Global carbon cycle; Lake carbon cycling; transport; Hydrologic CO; Lake functioning; Hydrologic CO2 transport
• DOI: 10.1007/s00114-018-1547-z
• ISSN: 0028-1042; 1432-1904

The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO 2 ) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO 2 production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO 2 production by mineralization as well as CO 2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of 0.70 − 0.31 + 0.27 to 1.52 − 0.90 + 1.09 Pg C yr −1 depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO 2 sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO 2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.