SP1.1 Dynamic enrichment processes of organic matter in the SML

海洋表面微层（SML）是海洋最上层的薄层，是空气和海洋之间相互作用的一部分，如气体交换，大气沉积和气溶胶排放。SML中的有机物（OM）富集改变了海气交换过程，但是哪些OM组分变得选择性富集，以及它们为什么和何时富集，在很大程度上仍然是未知的（Engel等人，2017年）。我们过去的研究表明，来源于光合自养生产的生物聚合物是SML的重要组分，并通过充当生物表面活性剂来影响空气-海洋交换（Galgani等人，2016; Engel等人，2018）和作为主要有机气溶胶的来源（Trueblood等人，2021年）。因此，我们的项目的动机是阐明和描述的动态富集过程的OM在SML，特别强调解决OM的来源。与我们的建模方法的目标是巩固我们的机械理解之间的联系浮游生物生长条件，生产和释放的生化物质，包括潜在的表面活性剂，和积累的OM内的SML。这种模型的开发将大大受益于BASS联合体各种子项目的成果和调查结果。相反，这是我们的动机，建立一个模型，成为适用的综合工具的解释和整合的领域，中观生态系统和实验室测量的OM富集在SML。与研究单位BASS-SP1. 1的相关性将破译SML中OM的来源、数量和生化组成，从而为所有BASS子项目提供重要信息。海洋表层有机质的主要来源是光合作用产物和新鲜产生的有机质的主要生化成分;即，碳水化合物、氨基酸和脂质在SML内受到微生物处理（SP1.2）和光反应（SP1.3、SP1.4），并且还补充溶解有机物（DOM）池（SP1.5）。SP1.1中的模型开发建立了OM的产生与其在SML中的富集之间的联系，并旨在通过解释海洋表层（SP2.2）和浮力（SP2.3）的动量通量变化来解决对海气交换（SP2.1）的相应影响。建议的SML子模型将根据SP1.4和SP2.3的结果进行改进。模型敏感性分析的结果将提供有关各种有机物的表面活性特性及其对海气交换过程的影响的补充信息，这些信息将在BASS内进行评估。

The sea-surface microlayer (SML) is the uppermost thin layer of the ocean and part of any interaction between the air and sea, such as gas exchange, atmospheric deposition, and aerosol emission. Organic matter (OM) enrichment in the SML modifies air-sea exchange processes, but which OM components become selectively enriched, as well as why and when they do, has remained largely unknown (Engel et al., 2017). Our past research showed that biopolymers derived from photoautotrophic production are important components of the SML and influence air-sea exchange by acting as biosurfactants (Galgani et al., 2016; Engel et al., 2018) and as a source of primary organic aerosols (Trueblood et al., 2021). Therefore, our project’s motivation is to elucidate and describe the dynamic enrichment processes of OM in the SML, with a particular emphasis on resolving OM sources. With our modelling approach the goal is to consolidate our mechanistic understanding of the linkages between plankton growth conditions, production, and the release of biochemicals, including potential surfactants, and the accumulation of OM within the SML. Such model development will greatly benefit from outcomes and findings of diverse subprojects of the BASS consortium. Conversely, it is our motivation to establish a model that becomes applicable as a synthesis tool for the interpretation and integration of field, mesocosm and laboratory measurements of OM enrichment in the SML. Relevance to the research unit BASS – SP1.1 will decipher the sources, amount, and biochemical composition of OM in the SML and thus, provide important information for all BASS subprojects. The primary origin of OM in the surface ocean is photosynthetic production and the major biochemical components of freshly produced OM; i.e., carbohydrates, amino acids, and lipids are subject to microbial processing (SP1.2) and photoreactions within the SML (SP1.3, SP1.4) and also replenish the pool of dissolved organic matter (DOM) (SP1.5). The model development in SP1.1 establishes a linkage between the production of OM and its enrichment within SML, and aims to resolve the corresponding effects on air-sea gas exchange (SP2.1) by accounting for changes in momentum flux on ocean surface layers (SP2.2) as well as in buoyancy (SP2.3). The proposed SML sub-model will be refined based on results from SP1.4 and SP2.3. Results from model sensitivity analyses will provide complementary information about surface-active properties of various OM and their impacts on air-sea exchange processes, which will be evaluated within BASS.