Integrated assessment on groundwater nitrate by unsaturated zone probing and aquifer sampling with environmental tracers

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• 作者：Lijuan Yuan ; Zhonghe Pang ; Tianming Huang
• 关键词：Soil water nitrate ; Groundwater nitrate ; Isotopes ; Evaporation ; Denitrification
• 刊名：Environmental Pollution
• 出版年：2012
• 出版时间：December, 2012
• 年：2012
• 卷：171
• 期：Complete
• 页码：226-233
• 全文大小：773 K

文摘

By employing chemical and isotopic tracers (¹⁵N and ¹⁸O in NO₃^?), we investigated the main processes controlling nitrate distribution in the unsaturated zone and aquifer. Soil water was extracted from two soil cores drilled in a typical agricultural cropping area of the North China Plain (NCP), where groundwater was also sampled. The results indicate that evaporation and denitrification are the two major causes of the distribution of nitrate in soil water extracts in the unsaturated zone. Evaporation from unsaturated zone is evidenced by a positive correlation between chloride and nitrate, and denitrification by a strong linear relationship between and ln(NO₃^?/Cl). The latter is estimated to account for up to 50 % of the nitrate loss from soil drainage. In the saturated zone, nitrate is reduced at varying extents (100?mg/L and 10?mg/L at two sites, respectively), largely by dilution of the aquifer water.