Methane emissions from two tundra wetlands in eastern Antarctica

During the summertime of 2005/2006 net methane (CH4)(CH4) fluxes and environmental variables were investigated in two tundra wetlands Wolong Marsh and Tuanjie Marsh of eastern Antarctica, using the closed chamber technique. At Wolong   Marsh, the measurements were made at four wet tundra sites, four mesic tundra sites, and two dry sites. CH4CH4 flux for wet tundra sites averaged 163.4μgm-2h-1 and for the mesic sites 132.4μgm-2h-1. For the dry sites, all the CH4CH4 fluxes showed the negative values with an average of -99.9μgm-2h-1. At Tuanjie   Marsh, flux measurements were made at two open ponds, two shallow fens and two dry sites. The average CH4CH4 flux for the pond sites was 170.4μgm-2h-1 and for the fen sites 134.7μgm-2h-1. For the dry sites CH4CH4 fluxes were approximately one order of magnitude lower than those for pond and fen sites and averaged 18.4μgm-2h-1. Spatial variations in CH4CH4 flux were primarily driven by the water table position at two tundra wetlands, whereas temporal variations in CH4CH4 flux from wet and mesic sites were related with the thermal regime of tundra soil layers. The fluxes from six observation sites showed a consistent diurnal cycle with the peak at 14:00 and the lowest at 2:00 (local time), which was correlated with ground temperature at the depth of 0–10 cm. The CH4CH4 emissions from coastal wetlands could constitute an important part of the annual CH4CH4 budget for Antarctic tundra ecosystems.