Fluorescence Properties and Chemical Composition of Fine Particles in the Background Atmosphere of North China

To understand the aerosol characteristics in a regional background environment, fine-particle (PM2.5, n = 228) samples were collected over a one-year period at the Shangdianzi (SDZ) station, which is a Global Atmospheric Watch regional background station in North China. The chemical and optical characteristics of PM2.5 were analyzed, including organic carbon, elemental carbon, water-soluble organic carbon, water-soluble inorganic ions, and fluorescent components of water-soluble organic matter. The source factors of major aerosol components are apportioned, and the sources of the fluorescent chromophores are further analyzed. The major chemical components of PM2.5 at SDZ were NO3-, organic matter, SO42-, and NH4+. Annually, water-soluble organic carbon contributed 48% +/- 15% to the total organic carbon. Secondary formation (52%) and fossil fuel combustion (63%) are the largest sources of water-soluble organic matter and water-insoluble organic matter, respectively. In addition, three humic-like and one protein-like matter were identified via parallel factor analysis for excitation-emission matrices. The fluorescence intensities of the components were highest in winter and lowest in summer, indicating the main impact of burning sources. This study contributes to understanding the chemical and optical characteristics of ambient aerosols in the background atmosphere.

Automated summary

This study collected PM2.5 samples over a one-year period at the Shangdianzi station in North China to analyze its chemical and optical characteristics. The major chemical components of PM2.5 were identified, and the sources of water-soluble organic matter and water-insoluble organic matter were determined. Additionally, different types of fluorescent components were identified and their intensity varied with seasons, indicating the main impact of burning sources. This study provides insights into the chemical and optical characteristics of ambient aerosols in the background atmosphere.