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Abstract

Little is known about the stable carbon isotopes of CH4 emission (�?´13CH4emitted) from permanently flooded rice field and double-rice field. CH4 fluxes and corresponding �?´13CH4emitted under various field managements (mulching, water regime, tillage, and nitrogen (N) fertilization) were simultaneously measured in three typical Chinese rice fields, a permanently ï¬�?ooded rice field in Ziyang City, Sichuan Province, Southwest China, a double-rice cropping field in Yingtan City, Jiangxi Province, Southeast China, and a rice-wheat rotation field in Jurong City, Jiangsu Province, East China, from 2010 to 2012. Results showed different seasonal variations of �?´13CH4emitted from the three fields during the rice-growing season. The values of �?´13CH4emitted were negatively correlated with corresponding CH4 emissions in seasonal variation and mean, indicating the importance of CH4 production, oxidation and transport associated with isotopic fractionation effects to the�?´13CH4emitted. Seasonal variations of �?´13CH4emitted were slightly impacted by mulching cultivation, tillage and N application but highly controlled by drainage. Meanwhile, tillage and N application, especially mulching cultivation, played important roles in mean CH4 emissions and corresponding �?´13CH4emitted, resulting in low emissions with high values of �?´13CH4. Totally, mean values of �?´13CH4emitted from the three fields were similar, mostly ranging from â�?�?60% to â�?�?50%, which is in good agreement with previously published data from India and America. The results demonstrated that seasonal variations of �?´13CH4emitted mainly depended on the changes in CH4 emission from paddy fields and further indicated that the methanogenic pathways, fraction of CH4 oxidation, and transport isotope fractionation influenced by field managements had important effects on �?´13CH4emitted.

Biography

Guangbin Zhang major study was the processes of CH4 emission from rice fields with the stable carbon isotope technique combining with microbes (methanogens and methanotrophs) analyses. Recently, he had carried out field experiments to study the mechanism of CH4 emission from a special kind of rice fields that are permanently flooded with highest fluxes in southeast of China. In addition, pot and incubation experiments were performed to investigate the effect of nitrogen fertilization on production, oxidation and emission of the CH4 by measuring the stable carbon isotopes, methanogens and methanotrophs. Meanwhile, integrated effects of nitrogen fertilization and straw application on N2O emission from paddy soils were observed. He is very interested in Soil Ecology, Microbiology, Biogeochemistry, Environmental and Soil Chemistry, and his focus is on the cycling of C and N in the agricultural ecosystem and the responses to global climate change (CO2 concentration and temperature enrichment).