Sources of methane in China

Continuous measurements of the methane flux from rice fields in Hangzhou，eastern China，arid Leshan，Sichuan Province，were carried out for 3 years．The results show that the methane flux from rice fields has a strong diurnal variation which may be explained by the soil temperature effects and rice plant growing activities，and that the day-mean flux has a large seasonal variation which may be related to soil temperature and the availability of organic substrate in the soil．An overall sources of methane for China are estimated while the rice fields are major sources，and the sewage tmatment is an important source of methane in China that has not been measure．Sewage in China is often treated in cesspools，which are similar to the biogas pits．However，no methane is recovered from such cesspools．We estimate that the total flux of methane from such sources may be of the oidcr of 10 Tg/a．The total emissions of methane from sources in China are estmmted to be about 40±lOTg/a．