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	Long-term changes in nutrient concentrations of the Changjiang River and principal tributaries
	Duan S. W. ; Xu F. ; Wang L. J.
	2007
关键词	Changjiang River nitrogen phosphorus silicon Si : N yangtze-river nitrogen-retention mississippi river inorganic nitrogen world rivers mass-balance china lake phosphorus transport
英文摘要	We present long-term nutrient data on the Changjiang River ( Yangtze River) at six hydrological stations and eight principal tributaries during the period 1958-1985. Three patterns of temporal changes were observed in nitrate (NO(3)(-)) and nitrite (NO(2)(-)): minimal variations in the upper catchment area, rapid increases in the middle watershed towards the end of the 1970s, and a gradual increase in the lower drainage basin. Prior to the 1970s, the level of NO(3)(-) throughout the Changjiang River system remained fairly constant. In the 1980s, however, this changed, with the lowest values in the upper Changjiang changing rapidly to the highest in the middle reaches and then declining slowly but steadily in the lower courses. Compared to NO(3)(-) and NO(2)(-); ammonium (NH(4)(+)) and soluble reactive phosphorus (SRP) showed smaller increases or no long-term variations, while dissolved silica (DSi) concentration generally decreased at most stations. These three patterns of NO(3)(-) and NO(2)(-) changes in the Changjiang River system were reflective of the difference in chemical fertilizer use and landscape features (e. g., slope, soil type and water body area) of the drainage basins of the primary tributaries. The decreases in DSi were most likely attributed to a reduction in suspended sediment loading due to dam constructions and increasing diatom consumption. The increase in NO(3)(-) and NO(2)(-) with a reduction in DSi concentrations in the Changjiang River could have significant effects on the stoichiometric balance of nutrients delivered to the East China Sea and the ecosystem in this dynamic region.
出处	Biogeochemistry
卷	85
期	2
页	215-234
收录类别	SCI
语种	英语
ISSN号	0168-2563
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/24093]
专题	地理科学与资源研究所_历年回溯文献
推荐引用方式 GB/T 7714	Duan S. W.,Xu F.,Wang L. J.. Long-term changes in nutrient concentrations of the Changjiang River and principal tributaries. 2007.

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