An Isotopic Tracer Experiment at the Ecosystem Scale

彼得森需要更好地了解河口的氮循环，以帮助解释氮素输入的人为变化如何影响沿海系统。我们建议通过在帕克河-普勒姆岛河口上游添加富含15N的溶解无机氮来对河口氮素动力学的概念和数值模型进行实验测试，帕克河-普勒姆岛河口是美国国家科学基金会资助的陆地边缘生态系统研究(LMER)计划的所在地。以前在森林流域、湖泊和河流上进行的整个系统的标记实验已经证明了示踪剂添加方法的可行性、有效性和成本效益。在派克河-梅子岛海湾河口，对添加的氮示踪剂分布的密集测量将得出氮在水、食物网组成部分和沉积物中的通量和停留时间的估计。15N添加试验将提供信息，以测试和改进河口N流的复杂模型，否则很难验证这些模型。该产品将极大地提高人们对氮在河流盐沼河口的运输、转化和去向的了解。

Peterson Improved understanding of the nitrogen cycle in estuaries is needed to help explain how anthropogenic changes in nitrogen inputs are affecting coastal systems. We propose to experimentally test conceptual and numerical models of nitrogen dynamics in an estuary by adding 15N-enriched dissolved inorganic nitrogen to the upper reaches of the Parker River-Plum Island Estuary, the site of and ongoing NSF-funded Land Margin Ecosystem Research (LMER) program. Previous whole system labeling experiments in forested watersheds, lakes and rivers have demonstrated there feasibility, power and cost effectiveness of the tracer addition approach. In the Parker River-Plum Island Sound estuary, intensive measurements of the distribution of the added nitrogen tracer will yield estimates of fluxes and residence times of nitrogen in water, food web components and sediments. The 15N addition experiment will provide information to test and refine complex models estuarine N flow that are otherwise very difficult to validate. The product will be greatly improved understanding of the transport, transformation, and fate of nitrogen in riverine saltmarsh estuaries.