Based on the aircraft observations in the summer of 2003, we have studied the aerodynamic size distributions of airborne particles at altitudes ranging from 400 m to 2800 m over the central and southern areas of Jiang...Based on the aircraft observations in the summer of 2003, we have studied the aerodynamic size distributions of airborne particles at altitudes ranging from 400 m to 2800 m over the central and southern areas of Jiangsu province located in Yangtse River Delta of China. The sizes of airborne particles are measured to be in a range of 0.47- 30 μm with 57 channels, and their number concentrations, surface area concentrations and mass concentrations are also measured. The results show that the concentrations of airborne particles are very low above an altitude of 2000 m and the size distributions present a specific multi-peak mode by using insufficient samples. Below 1000 m, however, the concentrations of particles increase obviously, and their size distribution is similar to that at the ground level. The study also indicates that the concentrations, size distributions and median diameters of airborne particles above and below the boundary layer are very different, displaying different pollution features. Meanwhile, the results also show that the pollution level of airborne particles has a descending tendency with altitude increasing.展开更多
A spectrometer combining electrical mobility sizing and aerodynamic sizing was developed to measure aerosol size distributions in the range of 3 nm to 10 μm. It includes three instruments which cover different size r...A spectrometer combining electrical mobility sizing and aerodynamic sizing was developed to measure aerosol size distributions in the range of 3 nm to 10 μm. It includes three instruments which cover different size ranges （a nano scanning mobility particle sizer （NSMPS, 3 - 60 nm）, a regular scanning mobility particle sizer （RSMPS, 40 - 700nm）, and an aerodynamic particle sizer （APS, 550nm- 10 μm））. High voltage and sheath flow of the NSMPS and RSMPS were supplied using two home-built control boxes. A LabVIEW program was developed for spectrometer automatic operation. A linear inversion method was applied to correct particle multiple charging effects and to integrate data from the three instruments into a wide-range size distribution. Experi- ments were conducted to compare distributions in the overlap size ranges measured by three instruments. Good agreement between the NSMPS and RSMPS was achieved after correcting for the difference in counting efficiencies of the two particle counters. Aerodynamic size distribu- tions reported by the APS were converted to mobility size distributions by applying an effective density method. Distributions measured by the RSMPS and APS were consistent in the overlap size range of 550 - 700 nm. A full spectrum in the size range of 3nm to 10~tm was demonstrated by measuring aerosol generated using a mixture of different sized polystyrene latex spheres.展开更多
ISO 16890:2016一般通风用空气过滤器标准是在欧美现有标准的基础上创建的用以确定空气过滤器对细颗粒物PM2.5等的计重过滤效率为目标的标准。该标准认为在给定的粒径范围内空气动力学当量直径可视为等同于光学当量直径,据此以空气过滤...ISO 16890:2016一般通风用空气过滤器标准是在欧美现有标准的基础上创建的用以确定空气过滤器对细颗粒物PM2.5等的计重过滤效率为目标的标准。该标准认为在给定的粒径范围内空气动力学当量直径可视为等同于光学当量直径,据此以空气过滤器对人工气溶胶的计径计数效率和典型大气气溶胶体积分布数学模型,计算得到对PM2.5等的计重过滤效率。欧洲并拟以此标准取代EN 779等现行标准。对ISO 16890:2016标准的相关问题进行了探讨,并对我国制定相关标准提出了一些看法和建议。展开更多
ISO 16890:2016《一般通风用空气过滤器》系列标准是首个测试并报告空气过滤器对大气悬浮颗粒物的质量过滤效率(ePMx)及分级的国际标准。结合ISO 16890:2016标准的主要创新或关键点,系统介绍了该标准的基本思路,并阐述了笔者对该标准的...ISO 16890:2016《一般通风用空气过滤器》系列标准是首个测试并报告空气过滤器对大气悬浮颗粒物的质量过滤效率(ePMx)及分级的国际标准。结合ISO 16890:2016标准的主要创新或关键点,系统介绍了该标准的基本思路,并阐述了笔者对该标准的一些认识和观点。就当前国内行业配合该标准的实施宜做的准备提出了建议。展开更多
文摘Based on the aircraft observations in the summer of 2003, we have studied the aerodynamic size distributions of airborne particles at altitudes ranging from 400 m to 2800 m over the central and southern areas of Jiangsu province located in Yangtse River Delta of China. The sizes of airborne particles are measured to be in a range of 0.47- 30 μm with 57 channels, and their number concentrations, surface area concentrations and mass concentrations are also measured. The results show that the concentrations of airborne particles are very low above an altitude of 2000 m and the size distributions present a specific multi-peak mode by using insufficient samples. Below 1000 m, however, the concentrations of particles increase obviously, and their size distribution is similar to that at the ground level. The study also indicates that the concentrations, size distributions and median diameters of airborne particles above and below the boundary layer are very different, displaying different pollution features. Meanwhile, the results also show that the pollution level of airborne particles has a descending tendency with altitude increasing.
基金We thank Dr. James Smith for his assistance on designing the control box and Ms. Zhiying Xie for her help on setting up the spectrometer. Financial supports from the National Natural Science Foundation of China （Grant Nos： 41227805, 21107060, 21190054 and 21221004）, National Key Basic Research and Development Program of China （Grant No： 2013CB228505）, and Beijing Natural Science Foundation （8122025） are acknowledged.
文摘A spectrometer combining electrical mobility sizing and aerodynamic sizing was developed to measure aerosol size distributions in the range of 3 nm to 10 μm. It includes three instruments which cover different size ranges （a nano scanning mobility particle sizer （NSMPS, 3 - 60 nm）, a regular scanning mobility particle sizer （RSMPS, 40 - 700nm）, and an aerodynamic particle sizer （APS, 550nm- 10 μm））. High voltage and sheath flow of the NSMPS and RSMPS were supplied using two home-built control boxes. A LabVIEW program was developed for spectrometer automatic operation. A linear inversion method was applied to correct particle multiple charging effects and to integrate data from the three instruments into a wide-range size distribution. Experi- ments were conducted to compare distributions in the overlap size ranges measured by three instruments. Good agreement between the NSMPS and RSMPS was achieved after correcting for the difference in counting efficiencies of the two particle counters. Aerodynamic size distribu- tions reported by the APS were converted to mobility size distributions by applying an effective density method. Distributions measured by the RSMPS and APS were consistent in the overlap size range of 550 - 700 nm. A full spectrum in the size range of 3nm to 10~tm was demonstrated by measuring aerosol generated using a mixture of different sized polystyrene latex spheres.
