Critical Role of Sea Spray Aerosol Production Pathways in Particulate Transfer Across the Sea-Air Interface

Sea spray aerosols (SSA) play a crucial role in transferring particulates from oceanic water to the atmosphere. The production pathways of SSA from bubble bursting include jet drops from bubble cavity collapse, surface film drops from bubble cap disintegration and collision film drops from underwater bubble collision. While the physical formation of these drops has been extensively studied, the mechanisms governing particle enrichment and transfer within these individual drop types remain poorly understood. This study systematically investigates particle enrichment and transfer across the three types of drops. While previous studies suggested only hydrophobic particles could be enriched by SSA, our findings reveal that both hydrophilic and hydrophobic particles can be enriched in all drop types, with surface film drops exhibiting significantly greater enrichment than previously reported. We propose for the first time that particle enrichment occurs during bubble film drainage because particles tend to remain within the thinning film rather than being uniformly drained out, leading to additional concentration within the film. These findings enhance our understanding of mass transfer at water-air interface.海洋飞沫气溶胶（Sea spray aerosols, SSA）在将颗粒物从海洋水体转移至大气的过程中发挥着至关重要的作用。由气泡破裂产生的SSA生成路径包括：气泡腔坍塌产生的射流液滴、气泡帽崩解产生的表面膜液滴，以及水下气泡碰撞产生的碰撞膜液滴。尽管学界已对这些液滴的物理形成过程开展了大量研究，但针对各类液滴内部颗粒物富集与迁移的调控机制，目前仍知之甚少。本研究系统探究了这三类液滴中的颗粒物富集与迁移过程。尽管既往研究认为仅疏水性颗粒物可通过SSA实现富集，但本研究结果显示，所有类型的液滴中均可实现亲水性与疏水性颗粒物的富集，且表面膜液滴的富集程度显著高于既往报道水平。本研究首次提出，颗粒物富集发生于气泡膜排液阶段：颗粒物更倾向于留存于逐渐变薄的膜内，而非被均匀排出，进而导致膜内颗粒物出现额外富集。上述研究结果加深了学界对水-气界面传质过程的认知。