Mapping Si and N Isotopes in Southern Ocean Surface Waters in Relation to Fe and Nutrient Concentrations and Diatom Valve Morphology

硅藻的硅（Si）和氮（N）稳定同位素组成是重建过去南大洋表层沃茨营养盐利用模式的两个主要替代物，这很有趣，因为南大洋浮游植物的生长影响大气二氧化碳水平，从而影响全球气候。我们将产生第一个关于地表沃茨中溶解的Si和N的同位素组成的数据集。我们将沿着一条从蓬塔阿雷纳斯（智利）到诺伊迈尔站（南极洲），向东到凯尔盖朗高原，然后到开普敦（南非）的横断面进行采样。我们还将测量溶解铁，营养和叶绿素浓度和硅藻的大小，Fragilariopsis kerguelensis。这些数据将提高我们的理解，揭示了空间尺度的营养物质的同位素组成的变化，以及如何同位素变化与环境因素，如浮游植物生长的铁限制的营养使用代理。观察到的硅藻形态的变化将有助于开发一个新的代理，一个潜在的铁的可用性或生产力制度。

The silicon (Si) and nitrogen (N) stable isotopic composition of diatoms are the two main proxies for reconstructing patterns of nutrient utilization in past Southern Ocean surface waters, interesting because the growth of Southern Ocean phytoplankton influences atmospheric carbon dioxide levels and thus global climate. We will produce the first dataset on the isotopic composition of dissolved Si and N in surface waters. We will sample along a transect from Punta Arenas (Chile) to Neumayer Station (Antarctica), east to the Kerguelen Plateau, and then up to Cape Town (South Africa). We will also measure dissolved iron, nutrient, and chlorophyll concentrations and the size of the diatom, Fragilariopsis kerguelensis. These data will improve our understanding of the nutrient use proxies by revealing the spatial scale over which variations in the isotopic composition of nutrients occur and how isotopic variations relate to environmental factors such as the iron limitation of phytoplankton growth. Observed changes in diatom morphology will aid development of a new proxy, one potentially for iron availability or productivity regime.