Using a dark enclosed chamber technique, the fluxes of CO2, N2O and CH4 from nature and disturbed grassland were measured on the spot in Inner Mongolian Temperate Grassland along the annual rainfall gradient section r...Using a dark enclosed chamber technique, the fluxes of CO2, N2O and CH4 from nature and disturbed grassland were measured on the spot in Inner Mongolian Temperate Grassland along the annual rainfall gradient section ranging from 450 to 200 mm. The results showed that the measured mean fluxes of CO2, N2O and CH4were (1 180.4 ±308.7), (0.010 ± 0.004) and (-0.039 ± 0.016) mg · m-2/h, respectively. The decrease of the fluxes of CO2, N2O and CH4 follows with that of annual rainfall gradient in the measurement area. Human activities, such as grazing and reclamation are also critical factors to affect the fluxes of these gases from grassland. Daily continuous measurement of CO2, N2O and CH4 fluxes showed a strong diurnal variation with higher emission in the daytime. A good relationship between the fluxes of CO2, N2O, CH4 and temperature was exposed in this study.展开更多
Aquaculture ponds are dominant features of the landscape in the coastal zone of China.Generally,aquaculture ponds are drained during the non-culture period in winter.However,the effects of such drainage on the product...Aquaculture ponds are dominant features of the landscape in the coastal zone of China.Generally,aquaculture ponds are drained during the non-culture period in winter.However,the effects of such drainage on the production and flux of greenhouse gases（GHGs）from aquaculture ponds are largely unknown.In the present study,field-based research was performed to compare the GHG fluxes between one drained pond（DP,with a water depth of 0.05 m）and one undrained pond（UDP,with a water depth of 1.16 m）during one winter in the Min River estuary of southeast China.Over the entire study period,the mean CO2flux in the DP was（0.75±0.12）mmol/（m^2·hr）,which was significantly higher than that in the UDP of（-0.49±0.09）mmol/（m^2·hr）（p0.01）.This indicates that drainage drastically transforms aquaculture ponds from a net sink to a net source of CO2in winter.Mean CH4and N2O emissions were significantly higher in the DP compared to those in the UDP（CH4=（0.66±0.31）vs.（0.07±0.06）mmol/（m^2·hr）and N2O=（19.54±2.08）vs.（0.01±0.04）μmol/（m^2·hr））（p〈0.01）,suggesting that drainage would also significantly enhance CH4and N2O emissions.Changes in environmental variables（including sediment temperature,p H,salinity,redox status,and water depth）contributed significantly to the enhanced GHG emissions following pond drainage.Furthermore,analysis of the sustained-flux global warming and cooling potentials indicated that the combined global warming potentials of the GHG fluxes were significantly higher in the DP than in the UDP（p〈0.01）,with values of739.18 and 26.46 mg CO2-eq/（m^2·hr）,respectively.Our findings suggested that drainage of aquaculture ponds can increase the emissions of potent GHGs from the coastal zone of China to the atmosphere during winter,further aggravating the problem of global warming.展开更多
森林在调控温室气体排放方面有重要作用,随着人工林的迅速发展,其温室气体通量和对施肥的响应逐渐引起广泛关注。为了解施氮对桉树人工林生长季和非生长季土壤温室气体通量的影响,在广西东门林场尾巨桉人工林样地设置低(84.2 kg N·...森林在调控温室气体排放方面有重要作用,随着人工林的迅速发展,其温室气体通量和对施肥的响应逐渐引起广泛关注。为了解施氮对桉树人工林生长季和非生长季土壤温室气体通量的影响,在广西东门林场尾巨桉人工林样地设置低(84.2 kg N·hm-2)、中(166.8 kg N·hm-2)、高(333.7 kg N·hm-2)3个施氮水平和不施氮对照,采用静态箱-气相色谱法监测土壤CO2、N2O和CH4通量。结果表明:(1)不同施氮处理的桉树人工林土壤CO2、CH4和N2O年均排放通量分别为214~271 mg CO2·m-2·h-1、-47^-37 kg CH4·m-2·h-1和16~203 kg N2O·m-2·h-1;土壤CO2排放通量在生长季高于非生长季,CH4和N2O通量未表现出明显季节变化。(2)施氮显著增加了土壤CO2和N2O年均排放通量,其促进效应主要集中在生长季(施氮后的4个月,即6—9月),且随时间增加,效应减弱。(3)施氮显著降低了土壤CH4年均吸收通量。因此,在维持桉树人工林生产力的基础上,结合季节变化,合理调控施氮量将有助于减少桉树林土壤温室气体排放。展开更多
文摘Using a dark enclosed chamber technique, the fluxes of CO2, N2O and CH4 from nature and disturbed grassland were measured on the spot in Inner Mongolian Temperate Grassland along the annual rainfall gradient section ranging from 450 to 200 mm. The results showed that the measured mean fluxes of CO2, N2O and CH4were (1 180.4 ±308.7), (0.010 ± 0.004) and (-0.039 ± 0.016) mg · m-2/h, respectively. The decrease of the fluxes of CO2, N2O and CH4 follows with that of annual rainfall gradient in the measurement area. Human activities, such as grazing and reclamation are also critical factors to affect the fluxes of these gases from grassland. Daily continuous measurement of CO2, N2O and CH4 fluxes showed a strong diurnal variation with higher emission in the daytime. A good relationship between the fluxes of CO2, N2O, CH4 and temperature was exposed in this study.
基金supported by the National Science Foundation of China (Nos. 41671088 and 41371127)the Program for Innovative Research Team of Fujian Normal University (No. IRTL1205)+2 种基金the Natural Science Foundation of Fujian Province, China (No. 2014J05046)the Study-Abroad Grant Project for Graduates of the School of Geographical Sciences, (No. GY201601)the Graduated Student Science and Technology Innovation Project of the School of Geographical Science,Fujian Normal University (No. GY201601)
文摘Aquaculture ponds are dominant features of the landscape in the coastal zone of China.Generally,aquaculture ponds are drained during the non-culture period in winter.However,the effects of such drainage on the production and flux of greenhouse gases（GHGs）from aquaculture ponds are largely unknown.In the present study,field-based research was performed to compare the GHG fluxes between one drained pond（DP,with a water depth of 0.05 m）and one undrained pond（UDP,with a water depth of 1.16 m）during one winter in the Min River estuary of southeast China.Over the entire study period,the mean CO2flux in the DP was（0.75±0.12）mmol/（m^2·hr）,which was significantly higher than that in the UDP of（-0.49±0.09）mmol/（m^2·hr）（p0.01）.This indicates that drainage drastically transforms aquaculture ponds from a net sink to a net source of CO2in winter.Mean CH4and N2O emissions were significantly higher in the DP compared to those in the UDP（CH4=（0.66±0.31）vs.（0.07±0.06）mmol/（m^2·hr）and N2O=（19.54±2.08）vs.（0.01±0.04）μmol/（m^2·hr））（p〈0.01）,suggesting that drainage would also significantly enhance CH4and N2O emissions.Changes in environmental variables（including sediment temperature,p H,salinity,redox status,and water depth）contributed significantly to the enhanced GHG emissions following pond drainage.Furthermore,analysis of the sustained-flux global warming and cooling potentials indicated that the combined global warming potentials of the GHG fluxes were significantly higher in the DP than in the UDP（p〈0.01）,with values of739.18 and 26.46 mg CO2-eq/（m^2·hr）,respectively.Our findings suggested that drainage of aquaculture ponds can increase the emissions of potent GHGs from the coastal zone of China to the atmosphere during winter,further aggravating the problem of global warming.
文摘森林在调控温室气体排放方面有重要作用,随着人工林的迅速发展,其温室气体通量和对施肥的响应逐渐引起广泛关注。为了解施氮对桉树人工林生长季和非生长季土壤温室气体通量的影响,在广西东门林场尾巨桉人工林样地设置低(84.2 kg N·hm-2)、中(166.8 kg N·hm-2)、高(333.7 kg N·hm-2)3个施氮水平和不施氮对照,采用静态箱-气相色谱法监测土壤CO2、N2O和CH4通量。结果表明:(1)不同施氮处理的桉树人工林土壤CO2、CH4和N2O年均排放通量分别为214~271 mg CO2·m-2·h-1、-47^-37 kg CH4·m-2·h-1和16~203 kg N2O·m-2·h-1;土壤CO2排放通量在生长季高于非生长季,CH4和N2O通量未表现出明显季节变化。(2)施氮显著增加了土壤CO2和N2O年均排放通量,其促进效应主要集中在生长季(施氮后的4个月,即6—9月),且随时间增加,效应减弱。(3)施氮显著降低了土壤CH4年均吸收通量。因此,在维持桉树人工林生产力的基础上,结合季节变化,合理调控施氮量将有助于减少桉树林土壤温室气体排放。
