Department of Chemistry and Biochemistry, ‡Scripps Institution of Oceanography, University of California, San Diego , La Jolla, California 92093, United States.
Anal Chem. 2017 Oct 3;89(19):10162-10170. doi: 10.1021/acs.analchem.7b00933. Epub 2017 Sep 22.
Ocean-derived microbes in sea spray aersosol (SSA) have the potential to influence climate and weather by acting as ice nucleating particles in clouds. Single particle mass spectrometers (SPMSs), which generate in situ single particle composition data, are excellent tools for characterizing aerosols under changing environmental conditions as they can provide high temporal resolution and require no sample preparation. While SPMSs have proven capable of detecting microbes, these instruments have never been utilized to definitively identify aerosolized microbes in ambient sea spray aersosol. In this study, an aerosol time-of-flight mass spectrometer was used to analyze laboratory generated SSA produced from natural seawater in a marine aerosol reference tank. We present the first description of a population of biological SSA mass spectra (BioSS), which closely match the ion signatures observed in previous terrestrial microbe studies. The fraction of BioSS dramatically increased in the largest supermicron particles, consistent with field and laboratory measurements of microbes ejected by bubble bursting, further supporting the assignment of BioSS mass spectra as microbes. Finally, as supported by analysis of inorganic ion signals, we propose that dry BioSS particles have heterogeneous structures, with microbes adhered to sodium chloride nodules surrounded by magnesium-enriched coatings. Consistent with this structure, chlorine-containing ion markers were ubiquitous in BioSS spectra and identified as possible tracers for distinguishing recently aerosolized marine from terrestrial microbes.
海洋来源的微生物存在于海雾气溶胶（SSA）中，它们作为云的冰核颗粒，具有影响气候和天气的潜力。单颗粒质谱仪（SPMS）可以原位生成单颗粒成分数据，是研究环境变化下气溶胶的优秀工具，因为它可以提供高时间分辨率，且无需样品制备。虽然 SPMS 已被证明能够检测微生物，但这些仪器从未被用于明确鉴定环境海雾气溶胶中的气溶胶化微生物。在这项研究中，我们使用气溶胶飞行时间质谱仪分析了在海洋气溶胶参考箱中由天然海水产生的实验室生成的 SSA。我们首次描述了生物 SSA 质谱（BioSS）的特征，其与先前陆地微生物研究中观察到的离子特征非常吻合。BioSS 在最大的超微米颗粒中的比例显著增加，这与气泡破裂喷出微生物的现场和实验室测量结果一致，进一步支持将 BioSS 质谱分配给微生物的结论。最后，通过对无机离子信号的分析，我们提出干燥的 BioSS 颗粒具有异质结构，微生物附着在氯化钠结上，周围是富含镁的涂层。与这种结构一致，BioSS 光谱中普遍存在含氯离子标记物，它们被认为是区分最近气溶胶化的海洋和陆地微生物的可能示踪剂。
