Preliminary budget of methane emissions from natural wetlands in China

Natural wetland excluding lake and floodplain in China at present covers an area of around 94,000 km2 and are mainly located in Qinghai-Tibet Highland ( 50%) and northeast China ( 30%), which can be divided into the peatlands ( 42,000 km2), freshwater marsh ( 25,000 km2), swamp ( 2,500 km2), and salt marsh ( 24,000 km2). The CH4 flux measured in 2001 and 2002 from the peatland in Qinghai-Tibet Highland and the freshwater marsh in Sanjiang Plain ranged from 0.16 to 10.0 and 1.18 to 54.6 mg CH4 m−2 h−1, and averaged 2.96 and 19.6 mg CH4 m−2 h−1, respectively. Based on our in situ measurement and the available data measured in the previous studies, the preliminarily estimated budget of CH4 emissions from natural wetlands in China was 1.48 Tg CH4 over the growing season and 1.76 Tg CH4 yr−1.