Climate Effects on Stream Nitrate Concentrations at 16 Forested Catchments in South Central Ontario

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• 作者：Shaun A. Watmough ; M. Catherine Eimers ; Julian Aherne ; and Peter J. Dillon
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：April 15, 2004
• 年：2004
• 卷：38
• 期：8
• 页码：2383 - 2388
• 全文大小：131K
• 年卷期：v.38,no.8(April 15, 2004)
• ISSN：1520-5851

文摘

Increased nitrate (NO₃) concentrations in streamwatersdraining forested catchments are reportedly an early indicatorof nitrogen (N) saturation. Nitrate concentrations instreams draining 16 forested catchments in south centralOntario were monitored over a 16-year period, duringwhich time N bulk deposition was relatively constant (~9kg ha^-1 yr^-1). Mean annual NO₃ concentrations instreams were both highly variable among catchments andamong years, although patterns of annual concentrationwere similar among many catchments. Coherence analysisidentified two stream groupings. Shallow soils, moderateslopes, low NO₃ concentration, and a large wetland componentcharacterized the first group. The second group hadprimarily upland characteristics including deeper soils,steeper slopes, higher NO₃ concentrations, and a muchsmaller wetland component. Patterns in NO₃ concentrationin wetland-influenced streams appeared to be related tosummer drought and cumulative frost depth, whereas NO₃concentrations in upland-draining streams appeared tobe related to both mean annual air temperature and summerdrought. Because a number of different climate parametersas well as the physical character of the catchmentsapparently influence NO₃ export, NO₃ concentrations instreams are not a good indicator of N saturation in thisregion.