Elucidating the influence of oceanic biological activity on the organic composition of sea spray aerosol (SSA) is crucial to understanding marine cloud properties relevant to climate. Numerous marine field studies designed to address this topic have yielded conflicting results mainly as a result of the inability to distinguish primary SSA composition from terrestrial and marine secondary organic aerosols. In this study, two laboratory-induced phytoplankton blooms were conducted in an isolated system without background aerosol contributions. Values for δ¹³C were measured for SSA (δ¹³C_SSA) along with seawater particulate and dissolved organic carbon (δ¹³C_POC and δ¹³C_DOC) to track changes in carbon transfer and composition between seawater and SSA. Contrary to common assumptions, δ¹³C_SSA values were not equivalent to δ¹³C_DOC. The consistently less negative δ¹³C_SSA values indicate that nascent δ¹³C_SSA reflects specific changes in relative contributions to SSA from the available seawater carbon pools, as a function of biological activity. A dual-source isotopic mixing model revealed that the difference between δ¹³C_SSA and δ¹³C_DOC was explained by increased relative contributions of “freshly produced” organic carbon (OC) to SSA, with the largest contribution of “freshly produced” OC occurring 2–3 days after the maximum chlorophyll-a concentrations. This finding is consistent with previous mesocosm studies, showing that organic enrichment in SSA requires processing by heterotrophic bacteria after periods of high primary productivity. This work examining the biological influences on SSA organic composition and nascent δ¹³C_SSA values provides new insights into ocean-to-SSA carbon transfer dynamics, which can be used in future field studies to improve estimates of anthropogenic influences on the carbon composition of the marine environment.

中文翻译：

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上δ生物影响¹³初生海C和有机构成喷雾气溶胶

阐明海洋生物活动对海浪气溶胶（SSA）有机组成的影响对于了解与气候有关的海洋云的性质至关重要。旨在解决该问题的许多海洋领域研究均产生了相互矛盾的结果，这主要是由于无法将主要SSA成分与陆地和海洋次生有机气溶胶区分开来。在这项研究中，在没有背景气溶胶作用的隔离系统中进行了两次实验室诱导的浮游植物水华。为δ值¹³测量了SSA（δ13 C ¹³ C ^ _SSA）与海水的微粒沿和溶解的有机碳（δ ¹³ C ^ _POC和δ ¹³ C ^ _DOC），以追踪海水与SSA之间的碳转移和组成变化。与一般的假设，δ ^13个Ç _SSA值不等于δ ¹³ Ç _DOC。一贯少负δ ¹³ C ^ _SSA值表明初生δ ¹³ Ç _SSA反映了从可用海水碳池SSA相对贡献的具体变化，作为生物活性的函数。双源同位素混合模型表明，δ之间的差¹³ Ç _SSA和δ ¹³ C ^ _DOC可以通过“新鲜生产的”有机碳（OC）对SSA的相对贡献增加来解释，其中“新鲜生产的” OC的最大贡献发生在最大叶绿素a浓度后2-3天。这一发现与以前的中观研究一致，表明SSA中的有机富集需要经过高初级生产力时期后由异养细菌进行处理。这项工作检查上SSA有机组合物和新生δ生物影响^13个Ç _SSA值提供新的见解海洋到SSA碳转移动力学，其可以在以后的实地研究被用来改善上的碳组合物人为影响的估计海洋环境。