Acta Geographica Sinica ›› 2001, Vol. 56 ›› Issue (5): 505-514.doi: 10.11821/xb200105001

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Nitrogen Biogeochemical Cycling in the Changjiang Drainage Basin and its Effect on Changjiang River Dissolved Inorganic Nitrogen: Temporal Trend for the Period 1968~1997

YAN Wei jin1, ZHANG Shen1, WANG Jia hui 2   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. Geology University of China, Beijing 100083, China
  • Received:2001-04-12 Revised:2001-06-27 Online:2001-09-15 Published:2001-09-15
  • Supported by:
    The knowledge-innovation project of CAS,No.KZCX2-207;The knowledge-innovation project of the Institute of Geographic Sciences and Natural Resources Research,CAS,No.CX10G-A00-06;National Natural Science Foundation of China,No.49801019

Abstract: In this paper, we present estimates of nitrogen (N) biogeochemical cycling in the Changjiang drainage basin, including N inputs, outputs and internal transfer for the period 1968 1997. The total N input, output and internal storage are approximately 10.0?10 9, 6.7?10 9, and 3.5?10 9 kg, respectively, in 1997, which is about fourfold, fivefold, and threefold of these in 1968, respectively. In terms of N inputs, N fixation was often a dominant input before 1977, providing about 1.0?10 9 kg year 1 ; while N fertilizer dominated N input after 1983, supplying an additional input of some 5.0?10 9 kg year 1 . In terms of N output, we estimate that the river dissolved inorganic nitrogen (DIN) concentration and flux have increased by about 10 fold from 1968 to 1997, reaching 1.60 mg L 1 and 1.40?10 9 kg, respectively, in 1997. Our study shows that about 25.0% of the total N input is transported through the river, while some 33% of the input is emitted by denitrification and volatilization, and the remaining 42% of the input is stored within the basin. The integrated N input, budget and storage have been linked to the increasing temporal trends of Changjiang River DIN. It is demonstrated that integrated N input, especially N fertilizer application, rather than human population density in the basin is the preferable predictor of the river DIN concentration and flux. Therefore, how N fertilizer is effectively applied is of crucial importance to the sustainable development of agriculture in the basin.

Key words: nitrogen, dissolved inorganic nitrogen, biogeochemical cycling, chemical fertilizer, Changjiang River, basin

CLC Number: 

  • X142