Emission and Atmospheric Transport of Particulate PAHs in Northeast Asia

TLDR

Seasonal variations in PAH concentrations across Northeast Asia arise from changes in Chinese emissions and transboundary transport driven by meteorology. The study combined particulate PAH measurements with the REAS‑POP emission inventory and the RAQM2‑POP chemical transport model to assess emissions, concentrations, and transport. Model simulations matched observations, confirming the REAS‑POP/RAQM2‑POP framework, while Beijing’s PAH levels were ~100‑fold higher than Noto’s and Noto exhibited a pronounced winter‑spring peak from coal‑related sources that diminished in summer when mobile‑source contributions rose.

Abstract

The emission, concentration levels, and transboundary transport of particulate polycyclic aromatic hydrocarbons (PAHs) in Northeast Asia were investigated using particulate PAH measurements, the newly developed emission inventory (Regional Emission inventory in ASia for Persistent Organic Pollutants version, REAS-POP), and the chemical transport model (Regional Air Quality Model ver2 for POPs version, RAQM2-POP). The simulated concentrations of the nine particulate PAHs agreed well with the measured concentrations, and the results firmly established the efficacy of REAS/RAQM2-POP. It was found that the PAH concentrations in Beijing (China, source region), which were emitted predominantly from domestic coal, domestic biofuel, and other transformations of coal (including coke production), were approximately 2 orders of magnitude greater than those monitored at Noto (Japan, leeward region). In Noto, the PAH concentrations showed seasonal variations; the PAH concentrations were high from winter to spring due to contributions from domestic coal, domestic biofuel, and other transformations of coal, and low in summer. In summer, these contribution were decrease, instead, other sources, such as the on-road mobile source, were relatively increased compared with those in winter. These seasonal variations were due to seasonal variations in emissions from China, as well as transboundary transport across the Asian continent associated with meteorological conditions.