Assessment of the Sources of Nitrate in the Changjiang River, China Using a Nitrogen and Oxygen Isotopic Approach

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• 作者：Si-Liang Li ; Cong-Qiang Liu ; Jun Li ; Xiaolong Liu ; Benjamin Chetelat ; Baoli Wang ; Fushun Wang
• 刊名：Environmental Science & Technology
• 出版年：2010
• 出版时间：March 1, 2010
• 年：2010
• 卷：44
• 期：5
• 页码：1573-1578
• 全文大小：252K
• 年卷期：v.44,no.5(March 1, 2010)
• ISSN：1520-5851

文摘

The Changjiang River is the largest freshwater river in China. Here, the sources and variability in nitrate of the Changjiang River are assessed for the first time using dual isotopic approach. Water samples were collected once in August 2006 from the main channel of the Changjiang and its major tributaries. The concentrations and isotopic composition of nitrate were then analyzed for the waters in the Changjiang River. The δ¹⁵N and δ¹⁸O of NO₃⁻ ranges from 7.3‰ to 12.9‰ and 2.4‰ to 11.2‰ in the Changjiang River waters, respectively. The ranges of isotopic compositions of nitrate suggested that nitrification (including “modified fertilizer”) and urban sewage effluent are the major sources of nitrate in the Changjiang River. The high δ¹⁸O-NO₃⁻ values were observed in the water of the upper reaches, indicated that the current drought might be one important reason for shifting of isotopes in the special sampling period. In addition, there was a strong positive relationship between δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻, which indicated that denitrification added to the enrichment of heavy isotopes of nitrate.