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Spatiotemporal variability of lake pCO 2 and CO 2 fluxes in a hemiboreal catchment
Author(s) -
Natchimuthu Sivakiruthika,
Sundgren Ingrid,
Gålfalk Magnus,
Klemedtsson Leif,
Bastviken David
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2016jg003449
Subject(s) - spatial variability , environmental science , carbon dioxide , dissolved organic carbon , atmosphere (unit) , hydrology (agriculture) , atmospheric sciences , upwelling , oceanography , geology , chemistry , meteorology , geography , statistics , mathematics , geotechnical engineering , organic chemistry
Globally, lakes are frequently supersaturated with carbon dioxide (CO 2 ) and are major emitters of carbon to the atmosphere. Recent studies have generated awareness of the high variability in pCO 2aq (the partial pressure corresponding to the concentration in water) and CO 2 fluxes to the atmosphere and the need for better accounting for this variability. However, studies simultaneously accounting for both spatial and temporal variability of pCO 2aq and CO 2 fluxes in lakes are rare. We measured pCO 2aq (by both manual sampling and mini loggers) and CO 2 fluxes, covering spatial variability in open water areas of three lakes of different character in a Swedish catchment for 2 years. Spatial pCO 2aq variability within lakes was linked to distance from shore, proximity to stream inlets, and deepwater upwelling events. Temporally, pCO 2aq variability was linked with variability in dissolved organic carbon, total nitrogen, and dissolved oxygen. While previous studies over short time periods (1 to 6 h) observed gas transfer velocity ( k ) to be more variable than pCO 2aq , our work shows that over longer time (days to weeks) pCO 2aq variability was greater and affected CO 2 fluxes much more than k . We demonstrate that ≥8 measurement days distributed over multiple seasons in combination with sufficient spatial coverage (≥8 locations during stratification periods and 5 or less in spring and autumn) are a key for representative yearly whole lake flux estimates. This study illustrates the importance of considering spatiotemporal variability in pCO 2aq and CO 2 fluxes to generate representative whole lake estimates.