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

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 (CO2) 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 CO2 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 CO2 production by mineralization as well as CO2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of [Formula: see text] to [Formula: see text] 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 CO2 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 CO2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.

Fil: Engel, Fabian. Uppsala University; Suecia

Fil: Farrell, Kaitlin J.. University of Georgia; Estados Unidos. Virginia Tech University; Estados Unidos

Fil: McCullough, Ian M.. University of California; Estados Unidos

Fil: Scordo, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina

Fil: Denfeld, Blaize A.. Universidad de Umea; Suecia

Fil: Dugan, Hilary A.. University of Wisconsin; Estados Unidos

Fil: de Eyto, Elvira. Marine Institute; Irlanda

Fil: Hanson, Paul C.. University of Wisconsin; Estados Unidos

Fil: McClure, Ryan P.. Virginia Tech University; Estados Unidos

Fil: Nõges, Peter. Estonian University of Life Sciences. Centre for Limnology; Estonia

Fil: Nõges, Tiina. Estonian University of Life Sciences. Centre for Limnology; Estonia

Fil: Ryder, Elizabeth. Dundalk Institute of Technology; Irlanda

Fil: Weathers, Kathleen C.. Cary Institute Of Ecosystem Studies; Estados Unidos

Fil: Weyhenmeyer, Gesa A.. Uppsala University; Suecia