Using 15N- and 18O-Values To Identify Nitr

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• 作者：Cong-Qiang Liu ; Si-Liang Li ; Yun-Chao Lang ; Hua-Yun Xiao
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：November 15, 2006
• 年：2006
• 卷：40
• 期：22
• 页码：6928 - 6933
• 全文大小：190K
• 年卷期：v.40,no.22(November 15, 2006)
• ISSN：1520-5851

文摘

Nitrate pollution of the karstic groundwater is anincreasingly serious problem with the development ofGuiyang, the capital city of Guizhou Province, southwestChina. The higher content of NO₃^- in groundwater comparedto surface water during both summer and winter seasonsindicates that the karstic groundwater system cannoteasily recover once contaminated with nitrate. In order toassess the sources and conversion of nitrate in thegroundwater of Guiyang, we analyzed the major ions, ¹⁵N-NH₄⁺, ¹⁵N-NO₃^-, and ¹⁸O-NO₃^- in surface and groundwatersamples collected during both summer and winterseasons. The results show that nitrate is the major dominantspecies of nitrogen in most water samples and there isa big variation of nitrate sources in groundwater betweenwinter and summer season, due to fast response ofgroundwater to rain or surface water in the karst area.Combined with information on NO₃^-/Cl^-, the variations ofthe isotope values of nitrate in the groundwater showa mixing process of multiple sources of nitrate, especiallyin the summer season. Chemical fertilizer and nitrificationof nitrogen-containing organic materials contribute nitrateto suburban groundwater, while the sewage effluentsand denitrification mainly control the nitrate distribution inurban groundwater.