Nitrification and denitrification are two key links of nitrogen flow cycle in soil.N2O and N2,generated from biochemical process of nitrogen,can cause not only the nitrogen losses and reduction of nitrogen use efficie...Nitrification and denitrification are two key links of nitrogen flow cycle in soil.N2O and N2,generated from biochemical process of nitrogen,can cause not only the nitrogen losses and reduction of nitrogen use efficiency,but also the boosted concentration of greenhouse gases,severely endangering the environment.Accordingly,nitrification-denitrification has been more and more concerned from whether an agricultural view,or an environmental one.Referring to the related literatures published at home and abroad in recent years,we overviewed the denitrification-caused N loss and N2O emission in various agro-ecosystems,and based on which we put forward countermeasures to reduce the denitrification-caused N loss and N2O emission and its research prospects in the future.展开更多
With the rapid development of modem industry and increase of consumption of the coal, petroleum and natural gas etc., emission of nitrogen oxide （NOx） from flue gas has air environment quality worsen day by day. Thi...With the rapid development of modem industry and increase of consumption of the coal, petroleum and natural gas etc., emission of nitrogen oxide （NOx） from flue gas has air environment quality worsen day by day. This research work is experimental study on removal low concentration NOx of flue gas by using solid absorbents. The experiment result shown that denification rate by modified activated carbon is higher than that of modified zeolite and rectorite. Average denitrification rate is 65.47% and maximum denitrification rate is 95.82% for activated carbon; average denitrification rate is respectively as 43.29% and 36.18%, maximum denitrification rate is respectively as 87.51% and 79.47% for modified zeolite and rectorite. Experiment results indicated that NO adsorption process of activated carbon can be described by Freudlich adsorption mode, K=0.143 and n=2.842 and Freudlich adsorption isotherm equation is： q = 0.143MO^0.3519.展开更多
Land-use patterns can affect various nutrient cycles in stream ecosystems, but little information is available about the effects of urban development on denitrification processes at the watershed scale. In the present...Land-use patterns can affect various nutrient cycles in stream ecosystems, but little information is available about the effects of urban development on denitrification processes at the watershed scale. In the presented study, we investigated the controlling factors of denitrification rates within the streams of the Han River Basin, Korea, with different land-use patterns, in order to enhance the effectiveness of water resource management strategies. Ten watersheds were classified into three land-use patterns （forest, agriculture and urban） using satellite images and geographic information system techniques, and in-situ denitrification rates were determined using an acetylene blocking method. Additionally, sediment samples were collected from each stream to analyze denitrifier communities and abundance using molecular approaches. In-situ denitrification rates were found to be in the order of agricultural streams （289.6 mg N20-N m-2 d-1） 〉 urban streams （157.0 mg N20-N m-2 d-1） 〉 forested streams （41.9 mg N20-N m-2 d-l）. In contrast, the average quantity of denitrifying genes was the lowest in the urban streams. Genetic diversity of denitrifying genes was not affected by watershed land-use pattern, but exhibited stream-dependent pattern. More significance factors were involved in denitrification in the sites with higher denitrification rates. Multiple linear regression analysis revealed that clay, dissolved organic carbon and water contents were the main factors controlling denitrification rate in the agricultural streams, while dissolved organic carbon was the main controlling factor in the urban streams. In contrast, temperature appeared to be the main controlling factor in the forested streams.展开更多
基金Supported by Key Natural Science Foundation of Fujian Province(2008J0120)Natural Science Foundation of Fujian Province(2006J0009)+1 种基金Non-profit Program from Science and Technology Department of Fujian Province(2009R10032-1 and 2010R1024-2)Special Fund for the Establishment of S&T Innovation Teams in Fujian Academy of Agricultural Sciences from Financial Department of Fujian Province(STIF-Y01)
文摘Nitrification and denitrification are two key links of nitrogen flow cycle in soil.N2O and N2,generated from biochemical process of nitrogen,can cause not only the nitrogen losses and reduction of nitrogen use efficiency,but also the boosted concentration of greenhouse gases,severely endangering the environment.Accordingly,nitrification-denitrification has been more and more concerned from whether an agricultural view,or an environmental one.Referring to the related literatures published at home and abroad in recent years,we overviewed the denitrification-caused N loss and N2O emission in various agro-ecosystems,and based on which we put forward countermeasures to reduce the denitrification-caused N loss and N2O emission and its research prospects in the future.
文摘With the rapid development of modem industry and increase of consumption of the coal, petroleum and natural gas etc., emission of nitrogen oxide （NOx） from flue gas has air environment quality worsen day by day. This research work is experimental study on removal low concentration NOx of flue gas by using solid absorbents. The experiment result shown that denification rate by modified activated carbon is higher than that of modified zeolite and rectorite. Average denitrification rate is 65.47% and maximum denitrification rate is 95.82% for activated carbon; average denitrification rate is respectively as 43.29% and 36.18%, maximum denitrification rate is respectively as 87.51% and 79.47% for modified zeolite and rectorite. Experiment results indicated that NO adsorption process of activated carbon can be described by Freudlich adsorption mode, K=0.143 and n=2.842 and Freudlich adsorption isotherm equation is： q = 0.143MO^0.3519.
基金Supported by the National Research Foundation of Korea(No.2013056833)
文摘Land-use patterns can affect various nutrient cycles in stream ecosystems, but little information is available about the effects of urban development on denitrification processes at the watershed scale. In the presented study, we investigated the controlling factors of denitrification rates within the streams of the Han River Basin, Korea, with different land-use patterns, in order to enhance the effectiveness of water resource management strategies. Ten watersheds were classified into three land-use patterns （forest, agriculture and urban） using satellite images and geographic information system techniques, and in-situ denitrification rates were determined using an acetylene blocking method. Additionally, sediment samples were collected from each stream to analyze denitrifier communities and abundance using molecular approaches. In-situ denitrification rates were found to be in the order of agricultural streams （289.6 mg N20-N m-2 d-1） 〉 urban streams （157.0 mg N20-N m-2 d-1） 〉 forested streams （41.9 mg N20-N m-2 d-l）. In contrast, the average quantity of denitrifying genes was the lowest in the urban streams. Genetic diversity of denitrifying genes was not affected by watershed land-use pattern, but exhibited stream-dependent pattern. More significance factors were involved in denitrification in the sites with higher denitrification rates. Multiple linear regression analysis revealed that clay, dissolved organic carbon and water contents were the main factors controlling denitrification rate in the agricultural streams, while dissolved organic carbon was the main controlling factor in the urban streams. In contrast, temperature appeared to be the main controlling factor in the forested streams.
