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Spatial variations in methane emissions from natural wetlands in China
Zhang, X. & Jiang, H.
Abstract
Natural wetlands are thought to be one of the
largest natural sources of atmospheric methane concentrations.
Although numerous studies referred to the rate of
methane fluxes in different geophysical regions, only a few
had estimates of the overall geographical methane
emissions in China. This study estimated the spatial
variations of annual methane emissions with the pixel size
of 1 km 9 1 km from natural wetlands, excluding water
surface, in China. The natural wetland areas were extracted
from the database of the 2000 land covers, and geophysical
divisions were used to represent different climate conditions.
Methane emission in every geophysical region was
calculated based on methane release factors obtained from
an extensive overview of published literature and the data
of elevation and vegetation proportion. The estimated
annual methane emissions ranged from 0 to 5,702.8 kg per
pixel within the area of 1 km2, and the spatial variation in
methane emissions was strongly correlated with proportion
of wetlands in the area. The total methane emission from
natural wetland in China ranged from 3.48 to 7.16 Tg
(terrogram, unit of weight) per year, with the mean value of
4.94 Tg per year, based on the area 133,000 km2 of natural
wetlands. Specifically, the wetland in Northeast China had
the highest contribution in China (39 %). Inner Mongolia
and Qinghai-Tibet highland represented for about 25 and
21 %, respectively. The other 15 % of the measured
methane was released in Northwest, North, Central, and
South China.
Keywords
Methane release; Geophysical region; Plant types; Wetland distribution
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