Evaluation of atmospheric particulate matter removal and influencing factors of common urban trees in Fuzhou, China

Five common urban tree species in Fuzhou, China, were selected to quantify the dry deposition of atmospheric particles and related water-soluble ions per unit leaf area using a three-layer membrane filtration method. Particulate matter (PM) measured included total suspended particles (TSP), PM ₁₀ ( d _p ≤ 10 µm), and PM _2.5 ( d _p ≤ 2.5 µm), while water-soluble ions included NO ₃ ⁻ and SO ₄ ²⁻ . The average dry deposition fluxes on leaf surfaces were 1.09, 0.058, 0.011, 0.021, and 0.027 mg/(m ² ·h) for TSP, PM ₁₀ , PM _2.5 , NO ₃ ⁻ , and SO ₄ ²⁻ , respectively. Corresponding average dry deposition rates were 0.61, 0.06, 0.021, 0.179, and 0.173 cm/s. Three-way analysis of variance showed that TSP flux exhibited significant interactions among time, region, and tree species. Sulfate interception trends indicated that Bischofia javanica captured more SO ₄ ²⁻ than other species, suggesting potential long-range transport of SO ₂ in December. Over the dry deposition periods (81–432 h), leaf surfaces did not reach saturation. Spearman correlation analysis revealed that dry deposition fluxes were positively correlated with atmospheric concentrations, with stronger correlations for larger particles. TSP deposition rates were weakly negatively correlated with temperature, relative humidity, and wind speed, with only temperature and relative humidity being significant. In contrast, PM ₁₀ and PM _2.5 deposition rates were positively correlated with relative humidity and negatively correlated with wind speed.