Inter- and intra-annual variations of pCO<inf>2</inf> and pO<inf>2</inf> in a freshwater subtropical coastal lake

Publication Type:
Journal Article
Citation:
Inland Waters, 2015, 5 (2), pp. 107 - 116
Issue Date:
2015-01-01
Full metadata record
Files in This Item:
Filename Description Size
\\utsfs.adsroot.uts.edu.au\homes\staff\108848\Desktop\IW-5.2.pdfPublished Version2.2 MB
Adobe PDF
© International Society of Limnology 2015. Inland waters emit significant amounts of carbon dioxide to the atmosphere, but tropical and subtropical lakes are underrepresented in current assessments. Here we present results of a 6-year study of the dynamics of surface partial pressures of carbon dioxide and oxygen (pCO < inf > 2 < /inf > and pO < inf > 2 < /inf > ) in a subtropical lake, Lake Peri, Brazil, to determine how temperature, rainfall, and wind moderate surface concentrations. Both pCO < inf > 2 < /inf > and pO < inf > 2 < /inf > tended to increase during the transitions between seasons when rainfall increased, with pCO < inf > 2 < /inf > averaging 2.5-3-fold higher than atmospheric values. Occasionally during autumn/winter, pCO < inf > 2 < /inf > similarly increased and pO < inf > 2 < /inf > decreased. We infer that the increases in both gases during the transition periods resulted from increasing inputs of allochthonous material into the lake. Those in winter resulted from near-bottom intrusions that intermittently reach the depth of measurement. In autumn/winter, pCO < inf > 2 < /inf > was 3-fold higher (average 1700 μatm) compared to spring/summer (550 μatm), whereas changes in pO < inf > 2 < /inf > did not have a clear seasonal pattern. Overall median net CO < inf > 2 < /inf > evasion was 11 mg C m < sup > -2 < /sup > d < sup > -1 < /sup > . Variability in the extent of rainfall and the associated high intra- and inter-annual variability in CO < inf > 2 < /inf > and CO < inf > 2 < /inf > emissions are in part controlled by atmospheric processes related to the South American Monsoon System and to El Niño Southern Oscillation cycles.
Please use this identifier to cite or link to this item: