Molecular insights into new particle formation across urban and polar environments

• Main Author: Brean, James
• Other Authors: Harrison, Roy, Shi, Zongbo, nerc
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: GE Environmental Sciences; QD Chemistry; Antarctic; Antarctic Peninsula; The Antarctic; Antarc*; Sea ice
• Online Access: http://etheses.bham.ac.uk//id/eprint/10645/1.hassmallThumbnailVersion/Brean2021PhD.pdf; http://etheses.bham.ac.uk//id/eprint/10645/; http://etheses.bham.ac.uk//id/eprint/10645/1/Brean2021PhD.pdf

New particle formation (NPF) is a process involving formation of thermodynamically stable molecular clusters and their subsequent growth to larger sizes. NPF modulates the earth’s radiative budget and poses potentially significant health effects, however, the mechanisms driving NPF globally are still uncertain due to limited molecular scale measurements. Urban measurements in both Beijing and Barcelona show highly oxygenated multifunctional organic molecules in high mixing ratios, arising primarily from anthropogenic VOC precursors. Efficient autoxidation due to high temperatures is offset by rapid peroxy radical termination due to high NO\(_x\) mixing ratios. Nucleation is seen to proceed by the nucleation of sulphuric acid, alkylamines, and HOMs in conjunction in Barcelona. An investigation of these mechanisms in the remote polar environment of the Antarctic Peninsula shows nucleation driven by sulphuric acid and amines, with elevations to both the sulphuric acid precursors and amines arising from the melt of sea ice. Particle formation rates are around two orders of magnitude more rapid in the urban environment than in the polar, and particle growth rates are around a single order of magnitude greater. This thesis demonstrates underappreciated roles of both anthropogenic VOC emissions in urban NPF and amine sources in polar regions in facilitating efficient NPF.