Nitrous oxide emissions to the atmosphere from an artificially oxygenated lake

Nitrous oxide (N2O) production at the sediment surface of eutrophic Lake Baldegg was quantified with three independent methods: pore‐water samplers, benthic chambers, and mass balances of the aerated‐oxygenated hypolimnion. N2O production at the sediment surface was the most important source in this lake and led to an accumulation in the hypolimnion during summer stratification. Highest rates of N2O emission to the atmosphere (24 µmol m−2 d−1) were observed after the onset of winter overturn, when hypolimnetic water enriched in N2O came in contact with the atmosphere. During summer stratification N2O emissions to the atmosphere decreased to ∼4 µmol m−2 d−1. The winter fluxes are close to the highest reported N2O emissions from marine systems.