Beyond stomata: Interspecific heterogeneity and structural controls of urban ozone deposition

Abstract. Urban environments are critical ozone (O3) hotspots where intense precursor emissions and high population densities escalate human exposure risks. Current deposition models typically rely on coarse land-use classifications, failing to capture the species-level heterogeneity at the city scale. We quantified O3 dry deposition across 20 common tree species in a subtropical megacity using a modified micrometeorological gradient method to derive species-resolved resistance parameters. Field measurements identified substantial interspecific variation: daytime canopy concentration gradients peaked at 10.02 ± 0.86 ppb (Platanus acerifolia). While standardized stomatal conductance correlates with the inverted minimum stomatal resistance (1/Rs, min, R2 = 0.36, P < 0.001), this relationship provides partial physiological support for the inferred resistance parameters. Sensitivity analysis showed that model-estimated deposition velocity was most sensitive to LAI, followed by wind speed and roughness length. Notably, a 20 % LAI increase reduced estimated deposition velocity by 17.55 % under the prescribed sensitivity experiments. These findings highlight species-level differences in O3 deposition and the coupled roles of canopy structure, aerodynamic transport, and physiological regulation. The resulting resistance estimates provide observational constraints for species-resolved parameterization in atmospheric deposition models, although their transferability requires further validation.