Regularity and estimation of methane emission from marshland in the Sanjiang Plain

The regularity of CH4 emission from marshland in the Sanjiang Plain was studied by sampling in the open field and analyzing under laboratory condition, the annual emission amount is also estimated. By Grey Relatively Analysis we know that the soil temperature in the 10cm depth of grassroot layer is close related with CH4 emission. CH4 emission has different kinds of diurnal emission modes: before-dawn maximum mode, night maximum mode and irregular fluctuation mode. The seasonal variation trend of CH4 emission rates is going up steadily from May to August and dropping down from September, the maximum lies behind the maximum of temperature. CH4 emission rates of different marshland types are different, the CH4 emission rate of Glyceriaspiculosa-Carex marshland is always higher than that of Carex lasiocarpa marshland. The paper also studies the difference of Ch4! emission rates in different managing modes and analyzes the emission rates between China and USA. The result shows: the average value of C4 emission rates is 17.26 mg/(m2.h), the annual amount of CH4 emission is about 0.75 Tg.