Department of Physics, Chemistry and Biology (IFM)

Lake Erssjön showed strong seasonal patterns in pCO_2, where the pCO₂ increased from a mean of  2090 ppm (SD=1049) between May to late July (period 1-4), to a mean of 5720 ppm (SD=1403) during mid to late August and early to mid-September (period 5 and 6) (the boxplots in the figure). Mean pCO₂ was highest in early September (mean= 6469 ppm, SD= 1494). The pCO₂ varied between days within a measurement period, but showed a larger variation and increase in pCO₂ towards late July (the end within period 4) (the lines in the Figure). 

The same seasonal pattern was also seen in the CO₂ flux in Lake Erssjön, where the measurements in mid-August to late September (measurement 5 to 7) showed markedly higher emissions (mean=111, SD= 52.5 mmol m^-2  day^-1), than the fluxes measured in the previous measurements (mean= 25,7, SD=16.9 mmol m^-2  day^-1). Lake Följesjön had constant high mean emissions throughout the season. There was a tendency for emitting more CO₂ from June to August (mean= 126, SD=67.9 mmol m^-2 day^-1), than in May and September (mean= 50.6, SD=0.9 mmol m^-2 day^-1).