Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 6 10 2009 10.5194/bg-6-2245-2009 http://www.biogeosciences.net/6/2245/2009/ http://www.biogeosciences.net/6/2245/2009/bg-6-2245-2009.html http://www.biogeosciences.net/6/2245/2009/bg-6-2245-2009.pdf 2245 2263 2009-10-26 Nutrient budgets for large Chinese estuaries S. M. Liu sumeiliu@ouc.edu.cn G.-H. Hong J. Zhang X. W. Ye X. L. Jiang Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China Korea Ocean Research and Development Institute, Ansan P.O. Box 29, Kyonggi 425-600, Republic of Korea State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China now at: Qingdao Entry-Exit Inspection and Quarantine Bureau of the People's Republic of China, Qingdao, 266001, China Chinese rivers deliver about 5–10% of global freshwater input and 15–20% of the global continental sediment to the world ocean. We report the riverine fluxes and concentrations of major nutrients (nitrogen, phosphorus, and silicon) in the rivers of the contiguous landmass of China and Korea in the northeast Asia. The rivers are generally enriched with dissolved inorganic nitrogen (DIN) and depleted in dissolved inorganic phosphate (PO₄^3−) with very high DIN: PO₄^3− concentration ratios. DIN, phosphorus, and silicon levels and loads in rivers are mainly affected by agriculture activities and urbanization, anthropogenic activities and adsorption on particulates, and rock types, climate and physical denudation intensity, respectively. Nutrient transports by rivers in the summer are 3–4 times higher than those in the winter with the exception of NH₄⁺. The flux of NH₄⁺ is rather constant throughout the year due to the anthropogenic sources such as the sewer discharge. As nutrient composition has changed in the rivers, ecosystems in estuaries and coastal sea have also changed in recent decades. 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