Dynamics of stream nitrate sources and flow pathways during stormflows on urban, forest and agricultural watersheds in central Pennsylvania, USA
Dynamics of stream nitrate sources and flow pathways during stormflows on urban, forest and agricultural watersheds in central Pennsylvania, USA
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DOI：
10.1002/hyp.7423
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发表时间：
2009-11-15
影响因子：
3.2
通讯作者：
DeWalle, David R.
中科院分区：
文献类型：
--
作者：
Buda, Anthony R.;DeWalle, David R.
了解风暴事件对硝酸盐（NO3-）动态的影响对于有效管理NO3-污染非常重要。在这项研究中，在宾夕法尼亚州中部一个201 km（2）的混合土地利用流域Spring Creek建立了5个代表从抗侵蚀砂岩覆盖的森林高地向喀斯特低地的下游发展的地点，这些高地具有农业、城市和混合土地利用。USA.在每个站点，在2005年的6次风暴事件中监测了河水，以评估从基流到峰流的NO3-（三角洲N-15-NO3-和三角洲O-18-NO3-）和水（三角洲O-18-H2O）的稳定同位素变化。事件NO3-和事件水的峰流量分数，然后使用双组分混合模型计算，以阐明NO3-流动途径之间的差异，五个网站。对于森林高地网站，风暴的大小似乎会影响NO3-源和流动途径。在小风暴（35毫米降雨量），事件NO3-分数小于事件的水分数在峰流量表明，NO3-被冲洗从存储源通过浅地下水流路径。对于城市化的网站，大气NO3-的冲刷是一个重要的NO3-源在洪峰流量，特别是在短时间的风暴事件水的贡献表明，盛行的漫流。在岩溶低地，非常低的分数的事件水，甚至更低的分数的事件NO3-在峰流量建议在风暴期间的地下水流途径的主导地位。这些地下水的流动路径可能会将储存的NO3-源冲入溪流，而喀斯特低地的深层土壤也可能促进NO3-同化。这项研究的结果说明了如何NO3-同位素和三角洲O-18-H2O可以结合起来，显示森林高地，岩溶山谷和完全城市化的流域之间的水和NO3-输送的关键差异。版权所有（C）2009约翰威利父子有限公司
Understanding the influence of storm events on nitrate (NO3-) dynamics is important for efficiently managing NO3- pollution. In this study, five sites representing a downstream progression of forested uplands underlain by resistant sandstone to karst lowlands with agricultural, urban and mixed land-use were established in Spring Creek, a 201 km(2) mixed land-use watershed in central Pennsylvania. USA. At each site, stream water was monitored during six storm events in 2005 to assess changes in stable isotopes of NO3- (delta N-15-NO3- and delta O-18-NO3-) and water (delta O-18-H2O) from baseflow to peakflow. Peakflow fractions of event NO3- and event water were then computed using two-component mixing models to elucidate NO3- flow pathway differences among the five sites. For the forested upland site, storm size appeared to affect NO3- sources and flow pathways. During small storms (35 mm rainfall), event NO3- fractions were less than event water fractions at peakflow suggesting that NO3- was flushed from stored sources via shallow subsurface flow pathways. For the urbanized site, wash-off of atmospheric NO3- was an important NO3- source at peakflow, especially during short-duration storms where event water contributions indicated the prevalence of overland flow. In the karst lowlands, very low fractions of event water and even lower fractions of event NO3- at peakflow suggested the dominance of ground water flow pathways during storms. These ground water flow pathways likely flushed stored NO3- sources into the stream, while deep soils in the karst lowlands also may have promoted NO3- assimilation. The results of this study illustrated how NO3- isotopes and delta O-18-H2O could be combined to show key differences in water and NO3- delivery between forested uplands, karst valleys and fully urbanized watersheds. Copyright (C) 2009 John Wiley & Sons, Ltd.