N2O as a sensitive indicator of denitrification in groundwaters

N2O 作为地下水反硝化的敏感指标

• 批准号: 357056-2007
• 负责人: Robertson, William
• 金额: $ 5.25万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Strategic Projects Supplemental Competition
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=365994
• 关键词: N2O; sensitive; indicator; denitrification; groundwaters

This proposal aims to determine the use of N2O as a sensitive indicator of denitrification in groundwater aquifers that are contaminated with nitrate (NO3-). NO3- is the most widespread contaminant of groundwater in Canada, largely due to the extensive addition of nitrogen (N) to agricultural lands through the application of synthetic fertilizers and animal wastes. N inputs to agricultural lands have increased dramatically within the last 30 years and this trend is expected to continue. Septic systems are also a major source of NO3- to groundwater aquifers. The drinking water limit for NO3- in Canada is 10 mg N/L and the Canadian aquatic life guideline for NO3- is 2.9 mg N/L. NO3- concentrations in excess of the limits threaten human health and aquatic life. Groundwater provides the baseflow to streams and rivers, thus NO3- contamination of groundwater directly affects the quality of surface water resources and the ecosystem health. In order to accurately assess and predict the fate of NO3- in groundwaters, detailed information is require on the processes that affect is concentration in the sub-surface. One of the most important NO3- removal processes in groundwater is denitrification, which reduces NO3- to harmless nitrogen gas (N2). Understanding the potential for denitrification in groundwater, and its rate, are thus central components in the development of effective N management strategies for sources of N to the sub-surface. Nitrous oxide (N2O) is produced as a bi-product of the denitrification of NO3- to N2. Routine analysis of dissolved N2O can be done at concentrations that are10,000 times lower than for typical nitrate analysis. Therefore, the detection of denitrification in groundwater by the accumulation of excess N2O is far more sensitive than analysing for the disappearance of NO3-. The use of N2O to assess denitrification activity in groundwater systems has not been previously explored. Results of this proposal will have implications for groundwater management, especially in designing wellhead protections schemes. It is expected that this research will produce a new method for the identification of denitrification activity in aquifers where analysis of NO3- concentrations would otherwise be inconclusive.

该建议旨在确定在被硝酸盐污染的地下水含水层中使用N2O作为敏化的敏感指标（NO3-）。 No3-是加拿大地下水中最广泛的污染物，这在很大程度上是由于通过应用合成肥料和动物废物广泛地增加了氮（N）为农业土地。在过去30年中，对农业用地的n投入急剧增加，预计这种趋势将继续下去。化粪池系统也是地下水含水层的主要来源。加拿大NO3的饮用水限制为10 mg N/L，NO3-的加拿大水生寿命指南为2.9 mg N/L。 NO3浓度超出了限制，威胁着人类健康和水生生命。地下水为溪流和河流提供了基础流，因此地下水不污染直接影响地表水资源和生态系统健康的质量。为了准确评估和预测地下水中NO3-的命运，对影响的过程需要详细信息。地下水中最重要的NO3去除过程之一是反硝化，它将NO3降低至无害的氮气（N2）。因此，了解地下水中硝化的潜力及其速率是开发有效的N管理策略n源为n源的核心组成部分。一氧化二氮（N2O）作为No3至N2的硝化的培养基产生。溶解的N2O的常规分析可以以比典型的硝酸盐分析低10,000倍的浓度进行。因此，与分析NO3-的消失相比，通过过量N2O的积累来检测地下水中的反硝化。以前尚未探讨使用N2O评估地下水系统中的非硝化活性的方法。该提案的结果将对地下水管理产生影响，尤其是在设计井口保护方案时。可以预期，这项研究将产生一种新方法，用于鉴定含水层中的硝化活性，在含水层的分析中，否则对NO3浓度的分析将是不确定的。