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输送至大气的过程中发挥着关键作用。SSA的气泡破裂生成路径主要包含三类：由气泡腔坍塌形成的射流液滴、由气泡帽解体产生的表面膜液滴，以及水下气泡碰撞引发的碰撞膜液滴。尽管学界已针对这类液滴的物理形成机制开展了广泛研究，但针对各类单个液滴类型内部颗粒物富集与输运的调控机制，目前仍知之甚少。本研究系统探究了三类液滴中的颗粒物富集与输运过程。既往研究曾提出，仅疏水性颗粒物可通过SSA实现富集，而本研究结果显示，亲水性与疏水性颗粒物均可在所有类型的液滴中实现富集，且表面膜液滴的颗粒物富集程度显著高于既往报道的水平。本研究首次提出，颗粒物富集过程发生于气泡膜排液阶段：由于颗粒物更易留存于逐渐变薄的膜层中而非被均匀排出，进而导致膜层内产生额外的浓度富集。上述研究结果深化了我们对水-气界面质量传递过程的认知。