Sinnett Gregory, Lenain Luc, Braham Emna, Chaudhry Nabihah A, Dinasquet Julie
Scripps Institution of Oceanography, University of California, San Diego, California 92093, United States.
Marine Physical Laboratory, University of California, San Diego, California 92093, United States.
Environ Sci Technol. 2025 Apr 15;59(14):7348-7356. doi: 10.1021/acs.est.4c14473. Epub 2025 Apr 3.
Sea-spray aerosol (SSA) plays a crucial role in climate processes by influencing radiative forcing, cloud formation, and precipitation. While SSA particles with diameters between 0.1 and 10 μm are commonly studied, larger aerosols (>20 μm) have been observed over terrestrial and oceanic regions but are generally overlooked. Large bioaerosols can be formed by pollen, fungal spores, and cell debris. However, the abundance, dynamics, and composition of large marine aerosols remain poorly understood. This study observed wave and atmospheric conditions driving aerosol production, the resulting SSA abundance, and sizes (up to 90 μm), and collected collocated SSA samples for microscopy analysis during a two-month time period. SSA above 20 μm were frequently observed, containing a diverse range of intact phytoplankton cells, including small flagellates (2 μm), to diatoms, and colonial cells (above 40 μm). The abundance of small flagellates suggests that sea-to-air transfer may be an important, yet overlooked, dispersal mechanism for these groups. To the best of our knowledge, this is the first evidence of direct airborne observation (rather than deposition) of large intact phytoplankton cells. These findings highlight the ubiquity of large marine aerosols and their capacity to carry intact phytoplankton cells.
海喷雾气溶胶（SSA）通过影响辐射强迫、云形成和降水在气候过程中发挥关键作用。虽然通常研究直径在0.1至10微米之间的SSA颗粒，但在陆地和海洋区域已观测到更大的气溶胶（>20微米），但通常被忽视。大生物气溶胶可由花粉、真菌孢子和细胞碎片形成。然而，大型海洋气溶胶的丰度、动态和组成仍知之甚少。本研究在两个月的时间内观测了驱动气溶胶产生的波浪和大气条件、由此产生的SSA丰度和大小（最大90微米），并采集了并置的SSA样本进行显微镜分析。经常观测到直径大于20微米的SSA，其中包含各种完整的浮游植物细胞，从小鞭毛藻（2微米）到硅藻，再到群体细胞（大于40微米）。小鞭毛藻的丰度表明，海-气传输可能是这些群体的一种重要但被忽视的扩散机制。据我们所知，这是首次直接在空气中观测到大型完整浮游植物细胞（而非沉积）的证据。这些发现突出了大型海洋气溶胶的普遍性及其携带完整浮游植物细胞的能力。
