Postdoctoral Fellowship: OPP-PRF: Deciphering the Role of Phytoplankton Community Composition in Southern Ocean Carbon Fluxes

碳主要通过溶解在海洋中或被陆地植物用于光合作用而离开大气。虽然调节南大洋碳通量的物理过程相对较好，但控制碳通量的生物过程受到的限制较少，部分原因是浮游植物空间和时间变异性的不确定性。确定南大洋浮游植物群落组成的特征很重要，因为不同类型的浮游植物会使用不同数量的碳。南大洋碳通量变化的预测受到阻碍，因为大多数模型在对碳通量进行参数化时没有区分不同类型的浮游植物。这项研究将提高人们对不同浮游植物物种如何改变进入表层海洋并被输出到南大洋深处的碳的数量的理解，从而限制气候预测。研究人员将通过绘制浮游植物群落组成图和描述每个分类群占主导地位的物理环境(例如，混合层深度、冰盖、一年中的时间、大量营养素浓度、海洋温度、区域)来解决这一问题。使用大气再分析、基于船舶的测量和生物地球化学SOCCOM浮标剖面的组合，研究人员将估计有多少碳进入海洋，有多少碳输出到深海，以及浮游植物的总量。最后，他们将结合浮游植物群落的组成来分析这些估计，以量化每个类群将碳输出到深海的效率。将模拟的浮游植物群落组成与海洋碳通量的估计相结合，将使研究人员能够探索浮游植物多样性在南大洋碳通量中的作用。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Carbon primarily leaves the atmosphere by dissolving in the ocean or by being used in photosynthesis by land plants. While the physical processes that modulate Southern Ocean carbon fluxes are relatively well understood, the biological processes controlling the fluxes are less constrained, due in part to uncertainties in phytoplankton spatial and temporal variability. Characterizing the phytoplankton community composition of the Southern Ocean is important because different types of phytoplankton will use different amounts of carbon. Projections of changes in Southern Ocean carbon flux are hampered since most models do not differentiate different types of phytoplankton when parameterizing carbon fluxes. This research will improve understanding of how different phytoplankton species will change the amount of carbon entering the surface ocean and being exported to depth in the Southern Ocean, constraining climate projections. The researchers will tackle this problem by mapping phytoplankton community composition and characterizing the physical environment (e.g., mixed layer depth, ice cover, time of year, macronutrient concentrations, ocean temperature, region) in which each taxa dominates. Using a combination of atmospheric reanalyses, ship-based measurements, and profiling biogeochemical SOCCOM floats, researchers will then estimate how much carbon enters the ocean, how much carbon is exported to the deep ocean, and the total amount of phytoplankton. Finally, they will analyze these estimates in concert with phytoplankton community composition to quantify how efficiently each taxa exports carbon to the deep ocean. Synthesizing modeled phytoplankton community composition with estimates of carbon fluxes in the ocean will enable researchers to explore the role of phytoplankton diversity in Southern Ocean carbon fluxes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.