title: An urban boreal lake basin as a source of CO₂ and CH₄.
abstract: Up to now, carbon gas fluxes from urban lakes in the boreal zone have seldom been studied. In summer 2005 we investigated fluxes from an urban boreal lake basin in southern Finland with long history of eutrophication and anoxia. Hypolimnetic CO₂ and CH₄ concentrations were high compared to other boreal lakes. During the open-water period, the lake basin acted as a source of CO₂ and CH₄ with fluxes of 2.10 mol m(-2 )and 0.04 mol m(-2), respectively. Despite the high oxidation rate (83%), CH₄ flux was higher than in other lakes and CH₄ contributed 33% [ corrected] to Global Warming Potential. The ratio of carbon emission to accumulation was 4, i.e. emissions were an important route for carbon departure but less so than in rural lakes. Since the lake oxygen conditions affected nutrient availability, there was a positive feedback from hypolimnion to carbon uptake, which was reflected in gas concentrations.
authors.affiliation: University of Helsinki, Department of Environmental Sciences, Niemenkatu 73, FIN-15140 Lahti, Finland. jessica.lopezbellido@helsinki.fi
authors.forename: Jessica
authors.initials: J
authors.lastname: López Bellido
authors.forename: Elina
authors.initials: E
authors.lastname: Peltomaa
authors.forename: Anne
authors.initials: A
authors.lastname: Ojala
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis*; D002947:Cities; D055669:Ecological and Environmental Phenomena; D004784:Environmental Monitoring; D005618:Fresh Water / Q000737:chemistry* / Q000382:microbiology; D008697:Methane / Q000032:analysis*; D010100:Oxygen / Q000032:analysis; D013696:Temperature; D014507:Urbanization; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014887:Weather
chemical_list: D000393:Air Pollutants; D014874:Water Pollutants, Chemical; D002245:Carbon Dioxide; D008697:Methane; D010100:Oxygen