Hygroscopic Properties Of Aerosol Particles Composed Of Multicomponent Organic Mixtures And Its Internal Mixtures With Inorganic Salts

The aerosol particles in atmosphere play a significant role on the Earth's environment.The water uptake of aerosol particles could not only affect the phase state of particles,but also influence their dry and wet deposition,atmospheric visibility,the formation of cloud condensation nuclei and human health.The atmospheric aerosols are composed of the organic materials and inorganic salts.The organic component can usually occupy 20-90% of atmospheric fine particulate matter while water soluble organic compounds(WSOC)take up a significant proportion in the organic components.Water soluble organic compounds can significantly alter aerosols' hygroscopicity.First,I introduce the existing hygroscopic tandem d ifferential mobility analyzer(H-TDMA)system in the laboratory.According to the problems occur in the system,related optimal adjustments have been made so that the system can accurately and reliably measure the aerosols' hygroscopic behavior within the range of 5%-90% RH.The hygroscopic behaviors of atmospherically relevant multicomponent water soluble organic compounds(WSOCs)and their effects on ammonium sulfate and sodium chloride were investigated using a HTDMA.The measured hygroscopic growth was compared with predictions from Extended-Aerosol Inorganics Model(E-AIM)and Zdanovskii-Stokes-Robinson(ZSR)method.The equal mass multicomponent WSOCs mixture containing levoglucosan,succinic acid,phthalic acid and humic acid showed gradual water uptake without obvious phase change over the whole RH range.It was found that the organic content played an important role in the water uptake of mixed particles.When organic content was dominant in the mixture(75%),the measured hygroscopic growth was higher than predictions from E-AIM or ZSR relation especially under high RH conditions.With mass fraction of organics not larger than 50%,the hygroscopic growth of mixtures was in good agreement with model predictions.The influence of interactions between inorganic and organic component on the hygroscopicity of mixed particles was related to the salt type and organic content.These results could contribute to understanding of the hygroscopic behaviors of multicomponent aerosol particles.