PHOsphorus Speciation in mineral Dust and Marine Aerosol Particles

维持海洋食物链和生物的浮游植物等海洋微生物的生长需要磷等宏观营养物质。另一方面，浮游植物物种向大气中排放与气候有关的有机化合物，例如DMS，这些化合物可以被氧化为硫酸，这可能随后导致新粒子的形成，这些粒子可以作为云的凝结核。因此，关于磷对这些微生物的有效性的信息对于理解海洋-大气相互作用非常重要。大气沉积是公海磷的主要来源；然而，仍然需要关于大气磷浓度通量、生物有效性和来源的信息，以了解它们在海洋中的命运，特别是在热带北大西洋和东南大西洋区域。现有的为数不多的数据主要是短期巡航测量，它们在理解季节周期和长期预测方面的应用有限。为了增进我们对这些海洋区域磷的来源和控制磷有效性和生物有效性的因素的了解，应对大气中的磷进行长期测量，包括尺寸分辨的和散装的气溶胶颗粒。此外，还将开发和优化分析方法(基于三种技术的组合)，以提高测定细颗粒中可溶磷和总磷的检测灵敏度，因为这种颗粒尺寸分数通常会遇到低负载。所获得的数据应用于调查这些区域中磷的主要来源，矿物粉尘、生物质燃烧、人为燃烧气溶胶等来源对磷的影响；这些区域中磷的形态(有机和无机成分)、溶解性、生物有效性、大气处理以及磷的季节变化。此外，应采用区域沙尘模式模拟，以更好地描述这些区域内的气溶胶输送和沉积。所获得的结果将有助于海洋-大气联合模式和理解控制大气磷在海洋中去向的关键因素。

Macro-nutrients such as phosphorous are required for the growth of oceanic microorganisms such as phytoplankton that sustain the oceans food chain and biology. On the other hand, phytoplankton species emit climate-relevant organic compounds, e.g, DMS to the atmosphere that can be oxidized to sulphuric acid, which may subsequently lead to the formation of new particles that can act as cloud condensation nuclei. Information about phosphorus availability to these microorganisms is, thus, very important for the understanding of the ocean-atmosphere interactions. Atmospheric deposition is the main source of phosphorus to the open ocean; however, information about atmospheric phosphorus concentration fluxes, bioavailability and sources which is necessary to understand their fate in the oceans especially in the regions of the tropical North and South-eastern Atlantic is still needed. The few available data are mainly short-term cruise measurements which are limited in their application to the understanding of seasonal cycles and long-term predictions. To improve our knowledge on the sources and factors controlling phosphorus availability and bioavailability in these oceanic regions, long-term measurements of atmospheric phosphorus in both size-resolved and bulk aerosol particles shall be performed. Furthermore, analytical methods will be developed and optimized (based on the combination of three techniques) to enhance the detection sensitivity for the determination of soluble and total phosphorus in fine mode particles due to the low loadings often encountered in this particle size fraction. The acquired data shall be used to investigate the main sources of phosphorus in these regions, the role of sources such as mineral dust, biomass burning; anthropogenic combustion aerosols on the; speciation (organic and inorganic composition), solubility, bioavailability, atmospheric processing, and the seasonal variation of phosphorus in these regions. In addition, a regional dust model simulation shall be applied to better describe the aerosol transport and deposition in these regions. The obtained results will be useful for combined ocean-atmosphere models and the understanding of the key factors controlling the fate of atmospheric phosphorus in the oceans.