Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closedchamber method in 1992 and 1993 and CH_4 emission from this region (total area of paddy soils was about1.88 milli...Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closedchamber method in 1992 and 1993 and CH_4 emission from this region (total area of paddy soils was about1.88 million hectares, of which 0.63 million hectares are distributed in the south of Jiangsu Province) wasestimated on the basis of the mean CH_4 fluxes observed. The results showed that the mean CH_4 flaxes fromlate rice and single cropping rice field were quite similar under the prevailing cultivation practices in theregion, being around 5 mg CH_4/m￣2/h (4.31-5.31 mg CH_4/m￣2/h for various cultivars of the late rice and3.20-6.22 mg CH_4/m￣2/h for various treatments of the single cropping rice). Total CH_4 emission from paddysoils in the region was estimated to be 0.185-0.359 Tg CH_4 per year. Continuously flooding the soil witha water layer till ripening caused higher mean CH_4 flux; and addition of nitrification inhibitor (thiourea)stimulated CH_4 emission. There was no simple relationship between CH_4 flux and either soil temperature orsoil Eh.展开更多
A high-resolution 2ooo-year methane record has been constructed from an ice core recovered at 7200 m a.s.1, on the Dasuopu Glacier in the central Himalayas. This sub-tropical methane record reveals an increasing trend...A high-resolution 2ooo-year methane record has been constructed from an ice core recovered at 7200 m a.s.1, on the Dasuopu Glacier in the central Himalayas. This sub-tropical methane record reveals an increasing trend in the concentration of methane during the industrial era that is similar to observations from polar regions. However, we also observed the differences in the atmospheric methane mixing ratio between this monsoon record and those from polar regions during pre-industrial times. In the time interval o N 1850 A.D., the average methane concentration in the Dasuopu ice core was 782±40 ppbv and the maximum temporal variation exceeded 200 ppbv. The difference gradient of methane concentration in Dasuopu ice core with Greenland and Antarctica cores are 66±40 ppbv and 107±40 ppbv, respectively. This suggests that the tropical latitudes might have acted as a major global methane source in preindustrial times. In addition, the temporal fluctuation of the pre-industrial methane records suggests that monsoon evolution incorporated with high methane emission from south Asia might be responsible for the relatively high methane concentration observed in the Dasuopu ice core around A.D. 800 and A.D. 1600. These results provide a rough understanding of the contribution of tropical methane source to the global methane budget and also the relationship betweenatmospheric methane and climate change.展开更多
Because of their diversity and abundance in a wide range of environments, particularly in cold regions, cold-adaptive archaea are expected to play a pivotal role in material recycling in cold environments. Methanogeni...Because of their diversity and abundance in a wide range of environments, particularly in cold regions, cold-adaptive archaea are expected to play a pivotal role in material recycling in cold environments. Methanogenic archaea are ubiquitous on earth and produce a large amount of methane （CH4） as their main carbon metabolite. Methanogens are the most laboratory amenda- ble archaea. The few psychrophilic archaea that have been cultured to date are mainly affiliated with methanogens, thus make them a good model for investigating mechanisms of archaeal cold adaptation. Studies of psychrotolerant methanogens have been ongoing since the 1990s. Using Methanocoecoides burtonii, a methanogen isolated from Ace Lake in Antarctica, exten- sive studies on the genomic characteristics associated with cold adaptation have been carried out by the Cavicchioli laboratory. We recently analyzed the genome of another psychrophilic methanogen and identified the gene repertoire associated with cold adaptation. This review summarizes recent studies of psychroactive methanogens, particularly their diversity, the genomics and proteomics associated with their cold adaptation, and the cellular components and proteins likely involved in their cold protec- tion.展开更多
文摘Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closedchamber method in 1992 and 1993 and CH_4 emission from this region (total area of paddy soils was about1.88 million hectares, of which 0.63 million hectares are distributed in the south of Jiangsu Province) wasestimated on the basis of the mean CH_4 fluxes observed. The results showed that the mean CH_4 flaxes fromlate rice and single cropping rice field were quite similar under the prevailing cultivation practices in theregion, being around 5 mg CH_4/m￣2/h (4.31-5.31 mg CH_4/m￣2/h for various cultivars of the late rice and3.20-6.22 mg CH_4/m￣2/h for various treatments of the single cropping rice). Total CH_4 emission from paddysoils in the region was estimated to be 0.185-0.359 Tg CH_4 per year. Continuously flooding the soil witha water layer till ripening caused higher mean CH_4 flux; and addition of nitrification inhibitor (thiourea)stimulated CH_4 emission. There was no simple relationship between CH_4 flux and either soil temperature orsoil Eh.
基金supported by the National Natural Science Foundation of China (40671044)the Ministry of Science and Technology of China (2005CB422004)
文摘A high-resolution 2ooo-year methane record has been constructed from an ice core recovered at 7200 m a.s.1, on the Dasuopu Glacier in the central Himalayas. This sub-tropical methane record reveals an increasing trend in the concentration of methane during the industrial era that is similar to observations from polar regions. However, we also observed the differences in the atmospheric methane mixing ratio between this monsoon record and those from polar regions during pre-industrial times. In the time interval o N 1850 A.D., the average methane concentration in the Dasuopu ice core was 782±40 ppbv and the maximum temporal variation exceeded 200 ppbv. The difference gradient of methane concentration in Dasuopu ice core with Greenland and Antarctica cores are 66±40 ppbv and 107±40 ppbv, respectively. This suggests that the tropical latitudes might have acted as a major global methane source in preindustrial times. In addition, the temporal fluctuation of the pre-industrial methane records suggests that monsoon evolution incorporated with high methane emission from south Asia might be responsible for the relatively high methane concentration observed in the Dasuopu ice core around A.D. 800 and A.D. 1600. These results provide a rough understanding of the contribution of tropical methane source to the global methane budget and also the relationship betweenatmospheric methane and climate change.
文摘Because of their diversity and abundance in a wide range of environments, particularly in cold regions, cold-adaptive archaea are expected to play a pivotal role in material recycling in cold environments. Methanogenic archaea are ubiquitous on earth and produce a large amount of methane （CH4） as their main carbon metabolite. Methanogens are the most laboratory amenda- ble archaea. The few psychrophilic archaea that have been cultured to date are mainly affiliated with methanogens, thus make them a good model for investigating mechanisms of archaeal cold adaptation. Studies of psychrotolerant methanogens have been ongoing since the 1990s. Using Methanocoecoides burtonii, a methanogen isolated from Ace Lake in Antarctica, exten- sive studies on the genomic characteristics associated with cold adaptation have been carried out by the Cavicchioli laboratory. We recently analyzed the genome of another psychrophilic methanogen and identified the gene repertoire associated with cold adaptation. This review summarizes recent studies of psychroactive methanogens, particularly their diversity, the genomics and proteomics associated with their cold adaptation, and the cellular components and proteins likely involved in their cold protec- tion.
