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水域营养物质利用模式的两个主要指标，有趣的是，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。我们将制作第一个关于地表水中溶解的硅和氮的同位素组成的数据集。我们将沿着样带从智利的蓬塔阿雷纳斯到南极洲的纽梅耶站，向东到科尔盖伦高原，然后向上到开普敦(南非)。我们还将测量溶解铁、营养物质和叶绿素的浓度以及硅藻Fragilariopsis kerguelsis的大小。这些数据将通过揭示营养物质同位素组成发生变化的空间尺度以及同位素变化与环境因素(如浮游植物生长的铁限制)之间的关系，提高我们对营养物质利用替代指标的理解。观察到的硅藻形态变化将有助于开发一种新的替代物，一种潜在的铁可获得性或生产力制度。

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.