A generalized wave-activity density,which is defined as an absolute value of production of three-dimensional vorticity vector perturbation and gradient of general potential temperature perturbation,is introduced and i...A generalized wave-activity density,which is defined as an absolute value of production of three-dimensional vorticity vector perturbation and gradient of general potential temperature perturbation,is introduced and its wave-activity law is derived in Cartesian coordinates. Constructed in an agoestrophic and nonhydrostatic dynamical framework,the generalized wave-activity law may be applicable to diagnose mesoscale weather systems leading to heavy rainfall. The generalized wave-activity density and wave-activity flux divergence were calculated with the objective analysis data to investigate the character of wave activity over heavy-rainfall regions.The primary dynamical processes responsible for disturbance associated with heavy rainfall were also analyzed. It was shown that the generalized wave-activity density was closely correlated to the observed 6-h accumulative rainfall. This indicated that the wave activity or disturbance was evident over the frontal and landfall-typhoon heavy-rainfall regions in middle and lower troposphere. For the landfall-typhoon rainband,the portion of generalized wave-activity flux divergence,denoting the interaction between the basic-state cyclonic circulation of landfall typhoon and mesoscale waves,was the primary dynamic process responsible for the evolution of generalized wave-activity density.展开更多
Carbon dioxide, methane and nitrous oxide are the major Greenhouse Gases (GHG’s), which emit from landfill areas and contribute significantly to global warming. Moreover, that the global warming potential of methane ...Carbon dioxide, methane and nitrous oxide are the major Greenhouse Gases (GHG’s), which emit from landfill areas and contribute significantly to global warming. Moreover, that the global warming potential of methane is 21 times higher than that of carbon dioxide and it has highest generation (60%) than other gases. Therefore, there is immense concern for its abatement or utilization from landfill areas. Compared to the west, the composition of municipal solid waste (MSW) in developing countries has higher (40% - 60%) organic waste. This would have potential to emit higher GHG’s from per ton of MSW compared to developed world. Beside that landfills areas in India are not planned or en- gineered generally low lying open areas, where MSW is indiscriminate disposed. This leads to uncontrolled emission of trace gases, foul smell, bird menace, ground and surface water pollution etc. Due to scarcity of land in big cities, mu- nicipal authorities are using same landfill for nearly 10 - 20 years. Hence, the possibility of anaerobic emission of GHG’s further increases. In the present paper we had quantified the methane emission from three MSW landfill areas of Delhi i.e., Gazipur, Bhalswa and Okhla. The results showed that the range of methane emission various in winter from 12.94 to 58.41 and in Summer from 82.69 - 293 mg/m2/h in these landfill areas. The paper has also reviewed the literature on methane emission from India and the status of landfill areas in India.展开更多
The increasing global demand for food production,often causing excessive use of chemical fertilizers,has led to the deterioration of soil health.Immediate action is required to restore soil health in a sustainable man...The increasing global demand for food production,often causing excessive use of chemical fertilizers,has led to the deterioration of soil health.Immediate action is required to restore soil health in a sustainable manner.This review advocates switching to use of organic matter(manure and compost)that contains vital nutrients for plant growth and helps restore soil health.Humic substances(HSs),derived from degraded plant remains and found ubiquitously in nature,are an important source of organic matter.The application of HSs to soil enhances essential nutrient supply and assimilation of atmospheric CO_(2)due to increasing biomass yield.Promoting HS application globally can help lower atmospheric CO_(2)concentrations and create a sustainable agricultural practice.However,the process of humification and the molecular structure of HSs remain poorly understood subjects in soil science.Therefore,it is imperative to understand the mechanisms underlying various roles of HSs in agroecosystems.This review offers an insight into the various structural and functional aspects of HSs,particularly fulvic acid and humic acid.The dynamic and interactive nature of HSs creates a framework for sustainable agriculture.展开更多
基金National Basic Research Program of China (2009CB421505)National Natural Sciences Foundations of China (40875032)
文摘A generalized wave-activity density,which is defined as an absolute value of production of three-dimensional vorticity vector perturbation and gradient of general potential temperature perturbation,is introduced and its wave-activity law is derived in Cartesian coordinates. Constructed in an agoestrophic and nonhydrostatic dynamical framework,the generalized wave-activity law may be applicable to diagnose mesoscale weather systems leading to heavy rainfall. The generalized wave-activity density and wave-activity flux divergence were calculated with the objective analysis data to investigate the character of wave activity over heavy-rainfall regions.The primary dynamical processes responsible for disturbance associated with heavy rainfall were also analyzed. It was shown that the generalized wave-activity density was closely correlated to the observed 6-h accumulative rainfall. This indicated that the wave activity or disturbance was evident over the frontal and landfall-typhoon heavy-rainfall regions in middle and lower troposphere. For the landfall-typhoon rainband,the portion of generalized wave-activity flux divergence,denoting the interaction between the basic-state cyclonic circulation of landfall typhoon and mesoscale waves,was the primary dynamic process responsible for the evolution of generalized wave-activity density.
文摘Carbon dioxide, methane and nitrous oxide are the major Greenhouse Gases (GHG’s), which emit from landfill areas and contribute significantly to global warming. Moreover, that the global warming potential of methane is 21 times higher than that of carbon dioxide and it has highest generation (60%) than other gases. Therefore, there is immense concern for its abatement or utilization from landfill areas. Compared to the west, the composition of municipal solid waste (MSW) in developing countries has higher (40% - 60%) organic waste. This would have potential to emit higher GHG’s from per ton of MSW compared to developed world. Beside that landfills areas in India are not planned or en- gineered generally low lying open areas, where MSW is indiscriminate disposed. This leads to uncontrolled emission of trace gases, foul smell, bird menace, ground and surface water pollution etc. Due to scarcity of land in big cities, mu- nicipal authorities are using same landfill for nearly 10 - 20 years. Hence, the possibility of anaerobic emission of GHG’s further increases. In the present paper we had quantified the methane emission from three MSW landfill areas of Delhi i.e., Gazipur, Bhalswa and Okhla. The results showed that the range of methane emission various in winter from 12.94 to 58.41 and in Summer from 82.69 - 293 mg/m2/h in these landfill areas. The paper has also reviewed the literature on methane emission from India and the status of landfill areas in India.
文摘The increasing global demand for food production,often causing excessive use of chemical fertilizers,has led to the deterioration of soil health.Immediate action is required to restore soil health in a sustainable manner.This review advocates switching to use of organic matter(manure and compost)that contains vital nutrients for plant growth and helps restore soil health.Humic substances(HSs),derived from degraded plant remains and found ubiquitously in nature,are an important source of organic matter.The application of HSs to soil enhances essential nutrient supply and assimilation of atmospheric CO_(2)due to increasing biomass yield.Promoting HS application globally can help lower atmospheric CO_(2)concentrations and create a sustainable agricultural practice.However,the process of humification and the molecular structure of HSs remain poorly understood subjects in soil science.Therefore,it is imperative to understand the mechanisms underlying various roles of HSs in agroecosystems.This review offers an insight into the various structural and functional aspects of HSs,particularly fulvic acid and humic acid.The dynamic and interactive nature of HSs creates a framework for sustainable agriculture.
