ABSTRACT Coastal ecosystems are under increasing stress from anthropogenic nutrient loading; which is most often assessed through water quality measurements. Here, 136 published studies on the use of δ15N to identify nutrient loading in coastal systems were analyzed to identify key strengths and challenges when using this isotope technique. δ15N has been used successfully for this purpose around the globe for over 40 years. Studies have mainly used benthic macroalgae and sediment samples in estuaries and coral reefs of North America and Oceania. Strengths of this technique include timely identification of nutrient loading and its sources, even when inputs are pulsed or assimilated by biota, the benefits of varying isotope turnover rates in different types of samples, sporadic sampling efforts, simple collection and preparation of samples, and relatively low analysis costs. The shortcomings of this technique have led to a loss in popularity in recent times, mainly from isotopic overlap of potential sources and the effects of other confounding factors on isotopic compositions. These challenges can be compensated by simultaneous measurement of other key variables including additional isotopes (δ13C, δ34S), water column nutrient concentrations, and fecal coliforms, highlighting great potential to use this tool.

中文翻译：

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δ15N 在确定沿海系统人为营养负荷方面的优势和挑战

摘要 沿海生态系统正受到人为营养负荷日益增加的压力；这通常是通过水质测量来评估的。在这里，对 136 份关于使用 δ15N 确定沿海系统营养负荷的已发表研究进行了分析，以确定使用这种同位素技术时的关键优势和挑战。40 多年来，δ15N 已在全球范围内成功用于此目的。研究主要使用北美和大洋洲的河口和珊瑚礁中的底栖大型藻类和沉积物样本。这种技术的优势包括及时识别营养负荷及其来源，即使输入被生物群脉冲或同化，不同类型样品中不同同位素周转率的好处，零星取样工作，样品的简单收集和制备，和相对较低的分析成本。这种技术的缺点导致近来不受欢迎，主要是由于潜在来源的同位素重叠和其他混杂因素对同位素组成的影响。这些挑战可以通过同时测量其他关键变量来弥补，包括额外的同位素（δ13C、δ34S）、水柱养分浓度和粪便大肠菌群，突出了使用该工具的巨大潜力。