Temporal and spatial variations of nitrous oxide fluxes from the littoral zones of three alga-rich lakes in coastal Antarctica

Abstract

Abstract Nitrous oxide (N 2 O) fluxes across air–water interface were investigated in the littoral zones of three alga-rich lakes (Lake Mochou , Lake Tuanjie and Lake Daming ) in east Antarctica during the summers of 2007/2008 and 2008/2009. In the littoral zones of these three lakes, the mean N 2 O fluxes were 3.1 ± 6.7 μgN 2 O–N m −2 h −1 , 2.5 ± 2.8 μgN 2 O–N m −2 h −1 and 7.2 ± 6.9 μgN 2 O–N m −2 h −1 , respectively. The fluxes showed a large temporal and spatial variation in lake littoral zones. On the whole, lake littoral zones were the emission sources for atmospheric N 2 O although negative fluxes occurred on most of the observation sites. The mean flux significantly correlated with NO 3 − –N concentration in the sediments at each site, suggesting that spatial variations of N 2 O fluxes have a connection with NO 3 − –N concentration. The seasonal pattern of the flux was positively related to daily radiation and air temperature and negatively to water depth, indicating that these factors and alga activity had an important effect on N 2 O emissions. The summertime N 2 O budget across air–water interface was estimated to be 6.7 mg N 2 O–N m −2 , 5.4 mg N 2 O–N m −2 and 15.6 mg N 2 O–N m −2 from the littoral zones of Lake Mochou , Lake Tuanjie and Lake Daming , respectively. Our results indicated that lake littoral N 2 O emissions could have a regional importance in coastal Antarctica.