Chemical characterization of organic compounds involved in iodine-initiated new particle formation from coastal macroalgal emission

Abstract

Abstract. Iodine-initiated new particle formation (I-NPF) has long been recognized in coastal hotspot regions. However, no prior work has studied the exact chemical composition of organic compounds and their role in coastal I-NPF. Here we present an important complementary study to the ongoing laboratory and field research on iodine nucleation in the coastal atmosphere. Oxidation and NPF experiments with vapor emissions from real-world coastal macroalgae were simulated in a bag reactor. On the basis of comprehensive mass spectrometry measurements, we reported for the first time a variety of volatile precursors and their oxidation products in gas and particle phases in such a highly complex system. Organic compounds overwhelmingly dominated over iodine in the new particle growth initiated by iodine species. The identity and transformation mechanisms of organic compounds were proposed in this study to provide a more complete story of coastal NPF from low-tide macroalgal emission.