1007 / 2024-09-20 02:36:12

Different Mechanisms and CCN Contribution of Atmospheric New Particle Formation Influenced by Marine and Continental Air Mass in Hangzhou Bay, a Coastal Area, China

New particle formarion, marine air mass, DMS, growth,CCN

Atmospheric new particle formation (NPF) is a widespread phenomenon both in continental and marine boundary layer, promote PM_2.5 formation and regulate climate through activating to cloud condensation nuclei (CCN). What are the features of the NPF in coastal area where continental and marine air mass interact frequently resulting in a mixture of gaseous precursors from different sources? How about the mechanisms and CCN contribution of NPF controlled by distinct types of gaseous precursors from continental and marine atmospheres? Twice intensive field campaigns were conducted at Haiyan site, as a coastal background receptor site, in a coastal area of Hangzhou Bay with massive petroleum chemistry industry emission, both in autumn (2023) and spring (2024), focusing on the mechanisms of nucleation, growth and CCN contribution of new particles influenced by different air masses and gaseous precursor sources.

The preliminary results show while continental air mass dominant, anthropogenic precursors mainly from industrial emissions, e.g. SO₂, NH₃ and anthropogenic volatile organic compounds (AVOCs) easily induce intense NPF with high formation rate and growth rate. Higher concentrations of SO₂ and NH₃ led to a sulfuric acid and base involved nucleation mechanism, and massive AVOCs oxygenated products grew new particles to CCN-related size range swiftly by condensation. Contrastingly, when shifting to marine air mass-controlled period, NPF was generally interrupted quickly due to lower concentration of anthropogenic precursors. When primary productivity in surrounding sea surface became lager in spring, moderate nucleation could be observed even under the control of marine air mass. Due to higher concentrations of gaseous dimethyl sulfide (DMS) and particle phase iodine during the nucleation, oxygenated products from marine precursors involved nucleation mechanism was speculated. However, new particles were not observed to grow across ~10 nm and activate to CCN at Haiyan site because of the pristine AVOCs condition in these circumstances. Nevertheless, new particle growth was enhanced along the transport to inner land by mixing with higher concentration of anthropogenic emissions. Moreover, when controlled by marine air mass mixing with industrial emissions from surrounding inlands indicated by a synchronous elevation of DMS and AVOCs (e.g. CH₃Cl), NPF with surprisingly fast nucleation and growth could also take place.

This study highlights anthropogenic precursors in continental air mass and marine precursors from air-sea exchange processes could induce nucleation with different mechanisms and CCN contribution, thus it illustrates the possibility of enhanced NPF due to the interaction of various gaseous precursors from marine and anthropogenic sources.