This study of Mikasa City in 2001, which analyzed N flow between N production and N load in seven agricultural and settlement subsystems, i.e., paddy, onion, wheat, vegetable, dairy, chicken, and citizen subsystems, a...This study of Mikasa City in 2001, which analyzed N flow between N production and N load in seven agricultural and settlement subsystems, i.e., paddy, onion, wheat, vegetable, dairy, chicken, and citizen subsystems, aimed to compare N flow in each subsystem, to determine the main sources of the N load, and to evaluate the influence of agricultural production and food consumption on N cycling in a rural area. The results showed that in Mikasa city, 38.5% of the N load came from point sources and the remainder from non-point sources with intensive vegetable farming imparting a serious N load. Because of the internal N cycling in the dairy subsystem, chemical fertilizer application was reduced by 70.2%, and 23.72 Mg manure N was recycled to the field; therefore, the N utilization efficiency was raised from 18.1% to 35.1%. If all the manure N in the chicken subsystem was recycled, chemical fertilizer application would be reduced by 8.1% from the present level, and the point sources of N pollution would be reduced by 20.8%.展开更多
Ecological city(eco-city) and its planning approach are emerging concepts in urban study,urban planning,ecological economics,environmental policy and corporate environmental management.However,opinions remain divided ...Ecological city(eco-city) and its planning approach are emerging concepts in urban study,urban planning,ecological economics,environmental policy and corporate environmental management.However,opinions remain divided over the connotation and denotation of the term"ecological city",what key issues ecocity planning can solve,and its specific contents.In this study,we present 10 basic propositions that define the eco-city and clarify its key parameters,thereby providing the basis for discussing the assumptions and principles underlying different approaches to sustainable urban development.We then summarize the concept and principles of an eco-city,and define the main requirements for ecocity planning.We conclude that an eco-city is a city in which the urban population,scale of land use and intensity of human activities are limited to the regional resource and environmental carrying capacity,which does not cause increasing or irreversible damage to the regional ecosystem's structure,functions and processes.展开更多
基金Project supported by the Science Research Foundation, Japan (No. 11460028).
文摘This study of Mikasa City in 2001, which analyzed N flow between N production and N load in seven agricultural and settlement subsystems, i.e., paddy, onion, wheat, vegetable, dairy, chicken, and citizen subsystems, aimed to compare N flow in each subsystem, to determine the main sources of the N load, and to evaluate the influence of agricultural production and food consumption on N cycling in a rural area. The results showed that in Mikasa city, 38.5% of the N load came from point sources and the remainder from non-point sources with intensive vegetable farming imparting a serious N load. Because of the internal N cycling in the dairy subsystem, chemical fertilizer application was reduced by 70.2%, and 23.72 Mg manure N was recycled to the field; therefore, the N utilization efficiency was raised from 18.1% to 35.1%. If all the manure N in the chicken subsystem was recycled, chemical fertilizer application would be reduced by 8.1% from the present level, and the point sources of N pollution would be reduced by 20.8%.
基金supported by the Knowledge Innovation Project of Chinese Academy of Sciences (grant no. KZCX2-YW-422)
文摘Ecological city(eco-city) and its planning approach are emerging concepts in urban study,urban planning,ecological economics,environmental policy and corporate environmental management.However,opinions remain divided over the connotation and denotation of the term"ecological city",what key issues ecocity planning can solve,and its specific contents.In this study,we present 10 basic propositions that define the eco-city and clarify its key parameters,thereby providing the basis for discussing the assumptions and principles underlying different approaches to sustainable urban development.We then summarize the concept and principles of an eco-city,and define the main requirements for ecocity planning.We conclude that an eco-city is a city in which the urban population,scale of land use and intensity of human activities are limited to the regional resource and environmental carrying capacity,which does not cause increasing or irreversible damage to the regional ecosystem's structure,functions and processes.
