Laboratory Study On The Activation Properties Of Typical Atmospheric Water Soluble Organic Nitrogen

Water soluble organic nitrogen（WSON）is an important component of aerosols in the atmosphere,which has an important impact on atmospheric nitrogen deposition,new particle formation,particulate hygroscopic growth,photochemical reactions,etc.,but the current understanding of its activation into clouds is still poorly understood.Therefore,in this study,two types of WSON of amino acids and nitrophenols with environmental representativeness of marine aerosol and urban aerosol were selected,on the basis of extensive study of the hygroscopicity of pure species using vapor sorption analyzer,7representative species were selected and the cloud condensation nucleus counter was used to focus on the activation performance of their pure components and mixed components under supersaturated conditions,so as to increase the understanding of the impact of activation into clouds of two major WSON in the atmosphere.The results of hygroscopicity studies show that the hygroscopicity of different amino acids is quite different,glycine and leucine are almost non-hygroscopic,arginine is less-hygroscopic,and lysine and proline are more-hygroscopic.Nitrophenols are a class of species that are mainly non-hygroscopic and less-hygroscopic.The results of activation experiments prove that WSON represented by amino acids are effective sources of cloud condensation nucleus（CCN）,while nitrophenols are not.The CCN activation of pure WSON species under supersaturated conditions basically corresponds to their hygroscopicity under subsaturated conditions,but there are exceptions,such as glycine.In general,inorganic salts are the most activated,nitrophenols are the weakest,and amino acids are generally between them.The recommendedκ_CCN value of sodium chloride is1.3323.The recommendedκ_CCN values of leucine,glycine,proline,arginine and lysine are 0.0456,0.3746,0.2279,0.1872 and 0.2048,respectively.The recommendedκ_CCNvalues of 4-nitrocatechol and 5-nitrosalicylic acid are 0.0759 and 0.0681,respectively.For pure inorganic salts and most amino acids,theκ_CCN values of pure substances under different supersaturated conditions are consistent,and the relationship between critical dry diameter Dc and supersaturation SS can be better unified on the sameκ_CCN line.For leucine in amino acids and nitrophenols,theκ_CCN values of these there substances at different supersaturations vary with the change of supersaturation.In general,at the same supersaturation,the larger theκ_CCN,the smaller the critical dry diameter Dc.At the same supersaturation,theκ_CCN of the inorganic salts are the largest and the Dc are the smallest.Nitrophenols’κ_CCN are the smallest,the Dc are the largest.Theκ_CCN and Dc of amino acids are between the two species.The activation of mixed components representing different environments is different,the mixed componentκ_CCN values representing marine aerosols are between0.1773-0.7604,the mixed componentκ_CCN values representing urban aerosols are between0.1637-0.4034,indicating that there are regional differences in the activation of aerosols.In the WSON-inorganic salt mixing components,when the mass of the inorganic salt is the main（75%）,theκ_CCN of the inorganic salt contributes greatly to the activation of the particulate.When the mass of WSON is dominant（75%）,theκ_CCN value of particulate is significantly reduced.Theκ_CCN prediction values of the ZSR method have good consistency with the measured values,indicating that the approximateκ_CCN value of the substance can be calculated under the condition of known aerosol components and theκ_CCN value of each component,which can be applied to reduce the uncertainty in model simulation and prediction.Experimental results show that WSON represented by amino acids may have a greater effect on the entire atmospheric life of atmospheric aerosols than currently recognized,including hygroscopic growth under subsaturated conditions and CCN activation under supersaturated conditions.