HR: 0830h
AN: B31C-0313    [PDF]
TI: CO$_{2}$ Fluxes From a Boreal Lake in Relation to Biological Activities
AU: * Huotari, J
EM: jussi.huotari@helsinki.fi
AF: University of Helsinki, Department of Ecological and Environmental Sciences, Niemenkatu 73, Lahti, Ham FIN-15140 Finland
AU: Ojala, A
EM: anne.ojala@helsinki.fi
AF: University of Helsinki, Lammi Biological Station, Paajarventie 320, Lammi, Ham FIN-16900 Finland
AU: Peltomaa, E
EM: elina.peltomaa@helsinki.fi
AF: University of Helsinki, Department of Ecological and Environmental Sciences, Niemenkatu 73, Lahti, Ham FIN-15140 Finland
AU: Rannik, Y
EM: rannik@mappi.helsinki.fi
AF: University of Helsinki, Department of Physical Sciences, P. O. Box 64, Helsinki, Uus FIN-00014 Finland
AU: Keronen, P
EM: petri.keronen@helsinki.fi
AF: University of Helsinki, Department of Physical Sciences, P. O. Box 64, Helsinki, Uus FIN-00014 Finland
AU: Vesala, T
EM: timo.vesala@helsinki.fi
AF: University of Helsinki, Department of Physical Sciences, P. O. Box 64, Helsinki, Uus FIN-00014 Finland
AB: Eddy covariance instrumentation with ultrasonic anemometer (USA-1, Metek, Germany) and closed-path infrared gas analyser (LI-7000, Li-Cor Inc., Lincoln, Nebraska, USA) was set up for continuous CO$_{2}$ flux measurements on a small humic lake in the boreal zone in southern Finland. The measurements were started at the beginning of June 2002 and continued until the lake froze over. The lake was sampled weekly for chemical data and biological stock parameters. Epilimnetic primary production and community respiration was also measured once a week to relate the CO$_{2}$ fluxes to the functioning of the lake ecosystem. Results showed diurnal as well as seasonal differences in CO$_{2}$ fluxes. In summer average hourly fluxes were always slightly negative around noon and early afternoon but in the morning and evening efflux was clear. Largest effluxes coincided with the highest epilimnetic water temperatures. In autumn diurnal variation in CO$_{2}$ flux was smaller and CO$_{2}$ was emitted from the lake throughout the day. However, the flux values at the time of fall turn-over were always fairly small. Also primary productivity and community respiration showed seasonal changes which could be related to the CO$_{2}$ fluxes. Relatively high community respiration confirmed the general role of the lake as a source of CO$_{2}$.
DE: 0315 Biosphere/atmosphere interactions
DE: 1600 GLOBAL CHANGE (New category)
DE: 1699 General or miscellaneous
DE: 1845 Limnology
SC: Biogeosciences [B]
MN: 2003 Fall Meeting