Fine Particle Emissions from On-Road Vehicles in the Zhujiang Tunnel, China

TLDR

Little is known about the characteristics of particulate matter emissions from vehicles in China, although such information is critical in source apportionment modeling, emission inventories, and health effect studies. The study reports a comprehensive characterization of PM2.5 emissions in the Zhujiang Tunnel, Pearl River Delta, China. The authors performed chemical speciation of PM2.5 into elemental carbon, organic carbon, inorganic ions, trace elements, and organic compounds, and derived separate emission factors for PM2.5 mass, elemental carbon, and organic matter for heavy‑ and light‑duty vehicles. Emission factors for individual species and their relative distributions were quantified for a mixed fleet (19.8% heavy‑duty, 80.2% light‑duty), revealing that trace element abundances varied more than in previous tunnel studies, while trace organic compound characteristics were consistent across studies, indicating that organic PM2.5 emissions are less affected by geography and fleet composition and thus better.

Abstract

Little is known about the characteristics of particulate matter emissions from vehicles in China, although such information is critical in source apportionment modeling, emission inventories, and health effect studies. In this paper, we report a comprehensive characterization of PM2.5 emissions in the Zhujiang Tunnel in the Pearl River Delta region of China. The chemical speciation included elemental carbon, organic carbon, inorganic ions, trace elements, and organic compounds. The emission factors of individual species and their relative distributions were obtained for a mixed fleet of heavy-duty vehicles (19.8%) and light-duty vehicles (80.2%). In addition, separate emission factors of PM2.5 mass, elemental carbon, and organic matter for heavy-duty vehicles and light-duty vehicles also were derived. As compared to the results of other tunnel studies previously conducted, we found that the abundances and distributions of the trace elements in PM2.5 emissions were more varied. In contrast, the characteristics of the trace organic compounds in the PM2.5 emissions in our study were consistent with characteristics found in other tunnel studies and dynamometer tests. Our results suggested that vehicular PM2.5 emissions of organic compounds are less influenced by the geographic area and fleet composition and thereby are more suitable for use in aerosol source apportionment modeling implemented across extensive regions.