Lake                        Erssjön               Följesjön

Area (ha)               6.2                     3.8

Mean depth (m)      1.7                     0.5

The CH₄ emissions were measured using floating chambers made of plastic buckets (0.077 m², 7489 mL) covered in aluminum tape to reflect the sunlight and heat. The chambers edges were submerged about 3 cm into the water, styrofoam was attached on the sides as a collar to make it float properly under different weather situations. In Lake Erssjön, plastic bottles were used to anchor the chambers, in Lake Följesjön no anchors were used instead the floating chambers were attached to the nearby boardwalk.

The floating chambers in Lake Erssjön were spatially placed in depth dependent transects. The spots were placed in seven transects with 2-4 spots in each, at depth interval of 0-1 m, 1-2 m, 2-3 m and >3 m. In Lake Följesjön one transect with four spots were chosen. Deployment time for the chambers lasted for either 24 or 48 hours.

All complementary measuerments were taken at a fixed spot in both lakes, every third week if nothing else is mentioned.

• Air samples before/after chamber deployment
• Water temperature (At every chamber)
• O₂ (% and mg/l)
• Water samples
  • CH₄ concentration (spatial distributed)
  • Ammonium (NH₄)
  • Nitrate (NO₃)
  • Phosphorus (P)
  • Nitrogen (N)
  • Dissolved organic carbon (DOC)
• Depth profiles in Lake Erssjön
  • CH₄ concentration
  • O₂ (% and mg/l)
  • Water temperature
• O₂ continuously every 15 minutes in Lake Erssjön
• Weather continuously every 30 minutes