PM_2.5 (particulate matter with an aerodynamic diameter less than or equal to 2.5μm), is a primary indicator of air pollution. Concentrations of water-soluble inorganic ions (NO₃^‒, SO₄^2‒, Cl^‒, Na⁺, Mg²⁺, K⁺, Ca²⁺ and NH₄⁺) in daily PM_2.5 samples were collected and analyzed in Haikou from September 2021 to August 2022. The air mass backward trajectories were calculated by using the National Oceanic and Atmospheric Administration (NOAA) Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. In winter, air pollution from the China mainland was the main contributor. In summer, the local emission was the main source of PM_2.5.
 

热带岛屿,气溶胶,化学