Aerosol physicochemical properties during two dust storms (DS1: March 30-31, and DS2: May 7-8) are measured in 2021 in Nanjing, aiming to investigate the impacts of dust storms on aerosol chemical compositions and optical hygroscopicity in the Yangtze River Delta (YRD). During DS1, the dust air masses are transported in the lower atmosphere and pass through the inlands and sea areas before reaching the YRD region. During DS2, the dust air masses are transported in the upper atmosphere and pass through the inlands only. Both them lead to an increase in black carbon (BC) mass fraction and a decrease in nitrate mass fraction in particles with diameters less than 2.5 μm near the surface. However, the impacts of DS1 and DS2 on the mass fractions of organics or sulfate are adverse. More coarse-mode dust aerosols in DS1 lead to a significant increase in aerosol scattering coefficient (σ_sp). The sulfate and weak-hygroscopicity aerosols (organics and BC) are also important to the change of σ_sp. During dust periods the enlarged mass ratio of sulfate to nitrate (greater than 4) promote aerosol deliquescence although dust aerosols can significantly weaken aerosol optical hygroscopicity. Different parameterization schemes are provided to fit aerosol light scattering enhancement factor (f(RH)) for dust and no-dust periods. The f(RH) closure study reveals an important impact of dust on the estimation of f(RH) based on aerosol chemical composition data. The dust air masses transported by different pathways have different impact on aerosol chemical compositions and optical hygroscopicity in the YRD region.

气溶胶,吸湿性,长三角,传输路径