Ti,C., Pan,J., Xia,Y. and Yan,X.(2012): A nitrogen budget of mainland China with spatial and temporal variation. Biogeochemistry, 198, 381-394.

『中国本土の時空間変動を伴う窒素収支』


Abstract
 The present study evaluated nitrogen (N) input and output in mainland China using updated data of temporally and spatially-based land use maps and statistical data at national and provincial scales. The total n inputs increased from 3,081 kg km-2 in 1985 to 5,426 kg km-2 in 2007. Chemical fertilizer dominated the N input and showed an increasing trend. Biological n fixation was the second important N input till 1990 and atmospheric deposition became the second most important source after that, accounting for 24.0% in 2007. There was no net n input through food/feed import in 1985, but it accounted for 3.5% of the total n input in 2007. According to a mass balance model, we assumed total N input equal to output. The results showed that more than half of the total N was denitrified or stored in the system. Ammonia volatilization accounted for 18.9-22.9% of the total N input, and N export to water bodies accounted for 17.9-20.7%. About 5.1-7.7% of the N input was emitted to the atmosphere through biomass burning. When calculated per unit area, total N input, n export to water bodies, denitrification and storage could be very well explained by human population density. Nitrogen input and major outputs were also positively related to per capita gross domestic product and the percentage of total land area used as cropland. The N budget is compared to that of some other countries and the environmental impacts of the N cycle is discussed.

Keywords: Nitrogen deposition; Chemical n fertilizer; Ammonia volatilization; Denitrification』

Introduction
Data and methods
 N budget model
 Basic data
 N inputs
  Biological fixation
  Chemical fertilizer
  Atmospheric wet and dry deposition
  Net food and feed import
 N outputs
  NH3 volatilization
  Reactive N export to water bodies
  Biomass burning emissions
  Denitrification and storage
 Uncertainty analyses of N budgets
Results
  Sources of N input
 N output and storages
Discussion
 Factors influencing N budget
 Comparison with N budget in other countries
 Riverine N export of the three major rivers
 Environmental consequences of the N budget
 Uncertainties in N budget
Acknowledgments
References


戻る