Research And Application Of Quantitative Method Of Organosulfates In Atmospheric Particles

In recent years, foreign scholars have detected a new kind of substances-organosulfate in the atmospheric particles, and found that they accounted forrelatively large proportion of atmospheric particles in heavily sulfur dioxidecontaminated areas. In China, sulfur dioxide pollution has been serious for a longtime. Therefore, there is a greater significance to investigate the contribution oforganosulfaes impacted by sulfur dioxide to atmospheric particles. With the aim oforganosulfates in atmospheric particles, this study has established a determinationmethod of organic carbon in organosulfates throμgh detecting the sulfuric acid rootin it, and provided necessary technical foundation for evaluating the contribution oforganosulfaets to atmospheric particles.The main research contents are as follows: organosulfates are treated as agroup and studied on the basis of their common functional group（sulfuric acid root）.The study includes establishing and optimizing an indirect spectrophotometricmethod to determine the content of sulfuric acid root; establishing the dissociationconditions of organosulfates to obtain total sulfuric acid root in particulate mattersand then the sulfuric acid root in organosulfates indirectly. The formation ofsecondary organic aerosol is simulated in a teflon bag, which contains differentconcentrations of sulfur dioxide and particles released from the biomass combustion.The results of the simulation are used to obtain the relation between the contents ofsulfur and organic carbon in organosulfates. The atmospheric particles are collected.According to the relation obtained from the research and measured content of sulfurin organosulfates in field particle samples, the content of organic carbon inorganosulfates（OCs-related）in field particles can be obtained. A ratio method is usedto study the contribution of organosulfates and inorganic sulfates formed by sulfurdioxide to particulate matters sampled in real atmosphere.The main experimental results are as follows. The indirect spectrophotometricmethod is mainly based on three chemical reactions, among which there is a positivecorrelation between sulfate and absorbance of the final colored product. Thestandard curve of indirect spectrophotometric method and the linear range areobtained. The optimum conditions of this obtained standard curve are alsoconfirmed. The recovery rates and relative standard deviation of this method indetermination of inorganic sulfate are obtained. Sodium dodecyl sulfate is choosedas the standard for organosulfates. The effective dissociation conditions fororganosulfates is confirmed. In the mixture of sodium sulfate and sodium dodecylsulfate, the recovery rates and relative standard deviation of this method in determination of total sulfuric acid root and inorganic sulfuric acid root are obained.The linear regression equation of organic carbon corresponding to the content ofsulfur in organosulfates is obtained, the correlation is well. Molar ratio of carbon tosulfur in organosulfates generated from biomass combustion products reacting withSO2is also calclated. In PM2.5collected at University Town of Shenzhen, watersoluble organic carbon, sulfuric acid root and organic carbon in organosulfates areanalyzed to evaluate the contribution of organosulfates to components in PM2.5.Even for such low amount of organosulfates, the indirect spectrophotometric methodis still able to detect sulfuric acid root in organosulfates. This result indicates thatthis method has wide application prospects in determination of organosulfates inatmospheric particles especially in heavy SO2polluted aeras.