Collaborative Research: Influence of the Riparian Zone on Nitrogen Cycling in Streams of Puerto Rico: Role of Nitrification and Denitrification

合作研究：河岸带对波多黎各溪流中氮循环的影响：硝化和反硝化的作用

• 批准号: 8718395
• 负责人: William Bowden
• 金额: $ 2.47万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-06-15 至 1990-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8718395&HistoricalAwards=false
• 关键词: Collaborative; Research; Influence; Riparian; Zone

This project will investigate fundamental processes that are likely to influence the behavior of nitrogen in tropical rain forest streams. Very little is known about hydrologic interactions between stream water and soil water or the potential influences such interactions could have on the nitrogen cycle in tropical ecosystems. Preliminary data collected in montane rain forest watersheds in Puerto Rico indicae that soil water carries large amounts of dissolved nitrogen as ammonium into the riparian zone. Very little ammonium or nitrate is found in stream water, however, suggesting that nitrogen is removed from solution before it enters bulk stream flow. It is important to determine whether the nitrogen removed from solution is exported from the ecosystem in a gaseous form by nitrification or denitrification or whether it is recycled internally by plant uptake. It is hypothesized that in these tropical streams: 1) available stream-side inorganic nitrogen supports an active nitrification- denitrification couple and that 2) this couple has a major influence on in-stream nitrogen chemistry. Furthermore, it is hypothesized that flow paths through the stream-side zone will have a predictable influence on nitrogen dynamics. To investigate these hypotheses work will be performed: 1) to established transect of observation wells on stream reaches with differing stream-side hydraulic characteristics and measure initial concentrations of inorganic and organic nitrogen at these sites; 2) test the effects of nitrogen enrichments on nitrogen chemistry at these sites; and 3) estimate the potential for nitrification and denitrification in laboratory soil and sediment systems, then quantify specific mechanisms of nitrogen loss with nitrogen-15 tracer techniques. This combination of field measurements, field manipulations, and laboratory experiments will enable us to examine the relative importance and spatial characteristics of nitrification, denitrification, and plant uptake in typical tropical stream ecosystems.

该项目将研究可能影响氮在热带雨林流中的行为的基本过程。 关于溪流水和土壤水之间的水文相互作用，或者这种相互作用可能对热带生态系统中的氮循环产生的水平相互作用知之甚少。 波多黎各山地雨林流域收集的初步数据表明，土壤水作为铵进入河岸带的大量溶解氮。 然而，在溪流中发现的铵或硝酸盐很少，这表明在进入散装流之前，从溶液中除去氮。 重要的是要确定从溶液中去除的氮是通过硝化或反硝化以气态形式从生态系统中导出的，还是通过植物摄取内部回收的氮。 假设在这些热带流中：1）可用的流侧无机氮支持活跃的硝化二硝化夫妇，而2）这对夫妇对流过的氮化学产生了重大影响。 此外，假设穿过溪流区域的流动路径将对氮动力学产生可预测的影响。 将进行这些假设的工作：1）在溪流覆盖范围内建立的观察井的样带，其液压特征不同，并测量了这些位点的无机和有机氮的初始浓度； 2）测试氮富集对这些位点氮化学的影响； 3）估计实验室土壤和沉积物系统中硝化和反硝化的潜力，然后用氮-15示踪技术量化氮损失的特定机制。 现场测量，现场操作和实验室实验的这种组合将使我们能够研究典型的热带流生态系统中硝化，反硝化和植物摄取的相对重要性和空间特征。