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2021 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 126, no 10, article id e2021JG006246Article in journal (Refereed) Published
Abstract [en]
Lakes are generally supersaturated in carbon dioxide (CO2) and emitters of CO2 to the atmosphere. However, estimates of CO2 flux (FCO2) from lakes are seldom based on direct flux measurements and usually do not account for nighttime emissions, yielding risk of biased assessments. Here, we present direct FCO2 measurements from automated floating chambers collected every 2-3 hr and spanning 115 24 hr periods in three boreal lakes during summer stratification and before and after autumn mixing in the most eutrophic lake of these. We observed 40%-67% higher mean FCO2 in daytime during periods of surface water CO2 supersaturation in all lakes. Day-night differences in wind speed were correlated with the day-night FCO2 differences in the two larger lakes, but in the smallest and most wind-sheltered lake peaks of FCO2 coincided with low-winds at night. During stratification in the eutrophic lake, CO2 was near equilibrium and diel variability of FCO2 insignificant, but after autumn mixing FCO2 was high with distinct diel variability making this lake a net CO2 source on an annual basis. We found that extrapolating daytime measurements to 24 hr periods overestimated FCO2 by up to 30%, whereas extrapolating measurements from the stratified period to annual rates in the eutrophic lake underestimated FCO2 by 86%. This shows the importance of accounting for diel and seasonal variability in lake CO2 emission estimates.
Place, publisher, year, edition, pages
Hoboken, United States: Wiley-Blackwell, 2021
Keywords
carbon dioxide fluxes; diel variability; automated flux chambers; lake greenhouse gas emissions; autumn mixing
National Category
Physical Geography
Identifiers
urn:nbn:se:liu:diva-181023 (URN)10.1029/2021JG006246 (DOI)000711969900032 ()2-s2.0-85118228286 (Scopus ID)
Note
Funding Agencies: Knut & Alice Wallenberg Foundation [2016.0083]; European Research Council (ERC) [725546]; Swedish Research Council, European Commission [2017-00635, 2016-04829]; FORMAS (the Swedish Research Council for Sustainable Development) [2018-01794]
2021-11-162021-11-162022-08-25Bibliographically approved