title: Role of a productive lake in carbon sequestration within a calcareous catchment.
abstract: For a long time, lakes were considered unimportant in the global carbon (C) cycle because of their small total area compared to the ocean. Over the last two decades, a number of studies have highlighted the important role of lakes in both sequestering atmospheric C and modifying the C flux from the catchment by degassing CO2 and methane and burying calcite and organic matter in the sediment. Based on a full C mass balance, high frequency measurements of lake metabolism and stable isotope analysis of a large shallow eutrophic lake in Estonia, we assess the role alkaline lakes play in augmenting the strength of terrestrial carbonate weathering as a temporary CO2 sink. We show that a large part of organic C buried in the sediments in this type of lakes originates from the catchment although a direct uptake from the atmosphere during periods of intensive phytoplankton growth in eutrophic conditions contributes to the carbon sink.
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia. Electronic address: peeter.noges@emu.ee.
authors.forename: Peeter
authors.initials: P
authors.lastname: Nõges
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia.
authors.forename: Fabien
authors.initials: F
authors.lastname: Cremona
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia.
authors.forename: Alo
authors.initials: A
authors.lastname: Laas
authors.affiliation: Institute of Geology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia.
authors.forename: Tõnu
authors.initials: T
authors.lastname: Martma
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia.
authors.forename: Eva-Ingrid
authors.initials: EI
authors.lastname: Rõõm
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia; Estonian Marine Institute, University of Tartu, Mäealuse 14, 12618 Tallinn, Estonia.
authors.forename: Kaire
authors.initials: K
authors.lastname: Toming
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia.
authors.forename: Malle
authors.initials: M
authors.lastname: Viik
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia.
authors.forename: Sirje
authors.initials: S
authors.lastname: Vilbaste
authors.affiliation: Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61117 Rannu, Tartu County, Estonia.
authors.forename: Tiina
authors.initials: T
authors.lastname: Nõges
mesh_terms: D002244:Carbon / Q000032:analysis*; D057486:Carbon Cycle; D057965:Carbon Sequestration; D017753:Ecosystem; D004957:Estonia; D060106:Lakes / Q000737:chemistry*; D008697:Methane
chemical_list: D002244:Carbon; D008697:Methane
keywords: Algal C-uptake; Calcite precipitation; Carbon burial; Carbonate weathering; Eutrophic alkaline lake; Stable isotope analysis