Vegetation near bird and seal rookeries typically has high δ15N signatures and these high values are linked to the enriched δ15N values of rookery soils. However, Antarctic cryptogams are mostly dependent on atmospheric ammonia (NH3) and volatized NH3 from rookeries is severely depleted in δ15N-NH3. So there is an apparent discrepancy between the isotopically depleted source (NH3) and δ15N-enriched vegetation. In this article, we aim to resolve this discrepancy to better understand the mechanisms and processes involved in isotopic changes during nitrogen transfer between Antarctic marine and terrestrial ecosystems. Under laboratory conditions, we quantified whether volatized NH3 affects the isotopic signature of cryptogams. NH3 volatilizing from penguin guano and elephant seal dung was depleted (44–49‰) in δ15N when captured on acidified filters, compared to the source itself. Cryptogams exposed to the volatized NH3 were enriched (18.8–23.9‰) in δ15N. The moss Andreaea regularis gained more nitrogen (0.9%) than the lichen Usnea antarctica (0.4%) from volatilized NH3, indicating a potential difference in atmospheric NH3 acquisition that is consistent with existing field differences in nitrogen concentrations and δ15N between mosses and lichens in general. This study clarifies the δ15N enrichment of cryptogams resulting from one of the most important nitrogen pathways for Antarctic vegetation.

中文翻译：

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氮同位素分馏解释了企鹅和海豹群落中挥发的氨对南极隐花鱼的 15N 富集

鸟类和海豹栖息地附近的植被通常具有高 δ15N 特征，这些高值与栖息地土壤中富含的 δ15N 值有关。然而，南极隐花鱼主要依赖于大气中的氨 (NH3)，来自栖息地的挥发 NH3 严重耗尽了 δ15N-NH3。因此，同位素耗尽源（NH3）和富含δ15N的植被之间存在明显差异。在本文中，我们旨在解决这一差异，以更好地了解南极海洋和陆地生态系统之间氮转移过程中同位素变化所涉及的机制和过程。在实验室条件下，我们量化了挥发的 NH3 是否影响密码花的同位素特征。当在酸化过滤器上捕获时，从企鹅粪便和象海豹粪便中挥发的 NH3 在 δ15N 中被消耗 (44–49‰)，与源本身相比。暴露于挥发 NH3 的隐花藻富含 (18.8–23.9‰) δ15N。苔藓 Andreaea regularis 从挥发的 NH3 中获得的氮 (0.9%) 比地衣 Usnea antarctica (0.4%) 多，表明大气 NH3 获取的潜在差异与现有的苔藓和地衣之间的氮浓度和 δ15N 的现场差异一致. 这项研究阐明了由南极植被最重要的氮途径之一引起的隐花植物的 δ15N 富集。表明大气 NH3 获取的潜在差异与一般苔藓和地衣之间氮浓度和 δ15N 的现有场差异一致。这项研究阐明了由南极植被最重要的氮途径之一引起的隐花植物的 δ15N 富集。表明大气 NH3 获取的潜在差异与一般苔藓和地衣之间氮浓度和 δ15N 的现有场差异一致。这项研究阐明了由南极植被最重要的氮途径之一引起的隐花植物的 δ15N 富集。