Constrain the source of nucleation mode particles using black carbon coating thickness in urban atmosphere

Abstract

Nucleation mode particles (NMPs, less than 25 nm in diameter) are ubiquitous in the atmosphere and have a negative impact on human health and climate. New particle formation (NPF) from extremely low volatile vapors is the dominating source of NMPs on the global scale, while direct emission from on-road vehicle is also an important source in the urban boundary layer. However, quantifying the contribution of NMPs in urban boundary layer from NPF and direct emission is a challenge owing to the complex source and evolution process of NMPs. Here, black carbon coating thickness, together with a fingerprint organic aerosol marker related to on-road vehicle emission (HOA, hydrocarbon-like organic aerosol), was utilized to distinguish and determine the two main sources of NMPs. Constrained by the approach, the influence of transport from upward-wind to the NMPs was excluded. The statistical results show that the contribution of NPF to NMPs is a dominant source under NPF, non-NPF and haze, whereas direct motor vehicle emissions is suggested as a relative constant contributor.