摘要
地球上９８％的氮素存在于原生岩（火成岩）中，但其对氮素循环贡献甚微；大气圈中的气态氮仅是地球中总氮素质量的１．９％，但实际上是供应所有生命需要的唯一氮源；生物圈中的氮量很小，然而全球植物初级净产物中９０％～９７％的氮在生物圈内循环。氮素在生物圈中的循环主要包括增加、损失和转化３个途径，这种循环因生态系统而不同。
The primary (igneous)rocks of the earth’s crust hold approximately 97.8%ofthe global N. However ,these rocks contribute very little to the cycling of N. Al-though gaseous N in the atmosphere represents only 19% of the earth’s total N mass,ithas apparently contributed virtually the sole source of N for nutrition of all forms oflife. In comparison with N contained in the atmosphere and lithosphere , the quantitiespresent in the biosphere are very small. However,on a global scale ,90～97% N contentof the net primary production of plant is derived from recycling of N within the bio-sphere. The N cycling in the biosphere include 3 ways in the main;additions ,losses andtransformations ,and the cycling varies with different ecosystems.
出处
《西北农业大学学报》
CSCD
1995年第1期93-97,共5页
Journal of Northwest Sci-Tech University of Agriculture and Forestry（Natural Science Edition)
关键词
氮素
循环
氮素分布
地圈
气圈
生物圈
N eycling ,N distribution ,lithosphere ,atmosphere, biosphere
