Department of Chemistry and Biochemistry and ‡Scripps Institution of Oceanography, University of California , San Diego, La Jolla, California 92093, United States.
Environ Sci Technol. 2017 Apr 4;51(7):3660-3668. doi: 10.1021/acs.est.6b06399. Epub 2017 Mar 27.
Knowledge of the surface composition of sea spray aerosols (SSA) is critical for understanding and predicting climate-relevant impacts. Offline microscopy and spectroscopy studies have shown that dry supermicron SSA tend to be spatially heterogeneous particles with sodium- and chloride-rich cores surrounded by organic enriched surface layers containing minor inorganic seawater components such as magnesium and calcium. At the same time, single-particle mass spectrometry reveals several different mass spectral ion patterns, suggesting that there may be a number of chemically distinct particle types. This study investigates factors controlling single particle mass spectra of nascent supermicron SSA. Depth profiling experiments conducted on SSA generated by a fritted bubbler and total ion intensity analysis of SSA generated by a marine aerosol reference tank were compared with observations of ambient SSA observed at two coastal locations. Analysis of SSA produced by utilizing controlled laboratory methods reveals that single-particle mass spectra with weak sodium ion signals can be produced by the desorption of the surface of typical dry SSA particles composed of salt cores and organic-rich coatings. Thus, this lab-based study for the first time unifies findings from offline and online measurements as well as lab and field studies of the SSA particle-mixing state.
了解海雾气溶胶（SSA）的表面成分对于理解和预测与气候相关的影响至关重要。离线显微镜和光谱学研究表明，干燥的超微米 SSA 往往是空间不均匀的颗粒，富含钠和氯的核心被富含有机物质的表面层包围，表面层含有少量的无机海水成分，如镁和钙。与此同时，单颗粒质谱揭示了几种不同的质谱离子模式，这表明可能存在许多化学上不同的颗粒类型。本研究调查了控制初生超微米 SSA 单颗粒质谱的因素。在通过玻璃滤器生成的 SSA 上进行的深度剖析实验，以及对通过海洋气溶胶参考箱生成的 SSA 的总离子强度分析，与在两个沿海地点观察到的环境 SSA 的观测结果进行了比较。利用受控实验室方法产生的 SSA 的分析表明，由典型的干燥 SSA 颗粒的表面解吸可以产生具有较弱钠离子信号的单颗粒质谱，这些颗粒由盐核和富含有机物质的涂层组成。因此，这项基于实验室的研究首次将离线和在线测量以及实验室和现场研究的 SSA 颗粒混合状态的结果统一起来。
