Investigation of the heterogeneous ice nucleation potential of sea spray aerosol

Abstract

Bubble bursting at the ocean surface generates smaller film-burst particles and larger jet drop particles that differ in composition. The chemical composition of sea spray aerosols is an important parameter for the evaluation of their impact on the global climate system. This study investigates the role of particle chemistry on the heterogeneous ice nucleation potential of laboratory-generated sea spray aerosols. Cultures of Procholorococcus, a highly abundant marine phytoplankton species, were used as a model source of organic sea spray aerosols. Results show that smaller particles generated from the lysed Procholorococcus cultures were organically enriched and effectively activated as ice nucleating particles at warmer temperatures and lower supersaturations than larger particles. The role of chemical composition in the activation of the particles was studied by measuring the nucleation abilities of single component organic molecules that mimic proteins, lipids, and carbohydrates in Procholorococcus. Amylopectin, agarose, and aspartic acid exhibited nucleation behaviors similar to particles generated from Procholorococcus cultures. Therefore, carbohydrates and proteins with numerous and well-ordered hydrophilic functional groups may determine the ice nucleation potential of organic sea spray aerosols.