塔里木盆地气溶胶粒度分布研究

使用Series 210收集了塔里木盆地内6个不同地点的气溶胶,获取了该地区气溶胶的粒度分布,并计算了对应的气溶胶数量中位直径。研究发现:在自然情况下,气溶胶分布遵循双峰分布的规律,其中第一峰值通常出现在0.5μm附近,第二峰值出现在3μm附近;由于采样点的气象条件、地表情况等差异所致,不同采样地点的峰位和峰面积有一定的差异;各采样点气溶胶分布规律显示,绝大多数气溶胶粒子粒径小于1μm。自然条件下,大多数采样点气溶胶粒子数量中位直径小于1μm。

气溶胶研究中大流量和小流量安德森采样器间的结果差异

大流量和小流量安德森分级采样器是气溶胶研究中比较经常使用的两种采样器,它们的基本原理虽然相同,但是由于采样量的不同也使得使用这两种采样器所得到的结果不尽相同.为了详细了解在气溶胶研究中这两种采样器的各自优缺点,详细比较了利用这两种采样器进行研究时所得到的结果(包括气溶胶总浓度,粒度分布,季节分布)的差别,并详细探讨了其原因.

铀燃料元件厂的空气净化

分析了放射性粉尘的特性 ,提出以公众导出空气浓度作为排风净化的目标 。

大气气溶胶遥感反演研究综述

随着城市工业化的发展,大气气溶胶污染日益严重,成为大气研究的重点。遥感技术作为科学、快速、大范围的监测手段,在大气研究中应用广泛。从大气辐射传输机理上对气溶胶光学厚度(AOD)、气溶胶浓度、粒度谱以及气溶胶与空气污染等4个主要研究内容进行了阐述,并分析了国内外气溶胶遥感反演的研究进展以及各种反演方法的优缺点。最后,对当前大气气溶胶反演存在的问题和研究趋势进行了讨论和展望。

A method to estimate concentrations of surface-level particulate matter using satellite-based aerosol optical thickness

We propose a new method to estimate surface-level particulate matter(PM)concentrations by using satellite-retrieved Aerosol Optical Thickness(AOT).This method considers the distribution and variation of Planetary Boundary Layer(PBL)height and relative humidity(RH)at the regional scale.The method estimates surface-level particulate matter concentrations using the data simulated by an atmospheric boundary layer model RAMS and satellite-retrieved AOT.By incorporation MODIS AOT,PBL height and RH simulated by RAMS,this method is applied to estimate the surface-level PM 2.5 concentrations in North China region.The result is evaluated by using 16 ground-based observations deployed in the research region,and the result shows a good agreement between estimated PM 2.5 concentrations and observations,and the coefficient of determination R2 is 0.61 between the estimated PM 2.5 concentrations and the observations.In addition,surface-level PM 2.5 concentrations are also estimated by using MODIS AOT,ground-based LIDAR observations and RH measurements.A comparison between the two estimated PM 2.5 concentrations shows that the new method proposed in this paper is better than the traditional method.The coefficient of determination R2 is improved from 0.32 to 0.62.

Role of ammonia in forming secondary aerosols from gasoline vehicle exhaust

Ammonia(NH3) plays vital roles in new particle formation and atmospheric chemistry. Although previous studies have revealed that it also influences the formation of secondary organic aerosols(SOA) from ozonolysis of biogenic and anthropogenic volatile organic compounds(VOCs), the influence of NH3 on particle formation from complex mixtures such as vehicle exhausts is still poorly understood. Here we directly introduced gasoline vehicles exhausts(GVE) into a smog chamber with NH3 absorbed by denuders to examine the role of NH3 in particle formation from GVE. We found that removing NH3 from GVE would greatly suppress the formation and growth of particles. Adding NH3 into the reactor after 3 h photo-oxidation of GVE, the particle number concentration and mass concentrations jumped explosively to much higher levels, indicating that the numbers and mass of particles might be enhanced when aged vehicle exhausts are transported to rural areas and mixed with NH3-rich plumes. We also found that the presence of NH3 had no significant influence on SOA formation from GVE. Very similar oxygen to carbon(O:C) and hydrogen to carbon(H:C) ratios resolved by aerosol mass spectrometer with and without NH3 indicated that the presence of NH3 also had no impact on the average carbon oxidation state of SOA from GVE.

Climatic change features of fog and haze in winter over North China and Huang-Huai Area

This paper revealed the climatic change characteristics of fog and haze of different levels over North China and Huang-Huai area(NCHH).It was found that the haze-prone period has changed from winter into a whole year,and the haze days(HD)in winter have increased significantly.The foggy days(FD)are half of HD.There are little difference on the number of days and trends of fog at various levels.The HD and FD show no obvious positive correlation until the 1980s.Fog has larger spatial scale,showing more in the south than in the north.Haze occurs mainly around large cities with a discrete distribution.In the background of weakened East Asian Winter Monsoon(EAWM)and sufficient particulate matter,the negative correlation between haze and wind speed is weakened,but the positive correlation between haze and moisture conditions(precipitation and humidity)is significantly strengthened.In recent years,small wind and variability appear frequently.Meanwhile,as the stable source and strong moisture absorption of the aerosol particles,the moisture condition becomes one key control factor in the haze,especially wet haze with less visibility.In contrast,the FD presents a stable positive correlation with precipitation and relative humidity,but has no obvious negative correlation with wind speed.

Seasonal characterization of components and size distributions for submicron aerosols in Beijing

Submicron aerosols （PMt） in Beijing were studied using an Aerodyne aerosol mass spectrometer （AMS） from January to Oc tober 2008. This paper presents seasonal variations of different chemical components （sulfate, nitrate, ammonium, chloride and organics） and size distributions of PM1. Results show that mass concentration of PMI was highest in summer, and lowest in autumn. Organics represented the dominant species in all seasons, accounting for 36%58% of PML, and their concentrations were highest in winter. Concentrations of inorganic components, sulfate, nitrate, and ammonium were highest in summer. Based on principal component analysis, organics were deconvolved and quantified as hydrocarbonlike and oxygenated organ ic aerosol （HOA and OOA, respectively）. HOA was highest in winter, accounting for about 70% of organics. However, OOA was highest in summer, and had lower values in autumn and winter. A similar diurnal pattern of various components was ob served, which is higher at nighttime and lower during daytime. HOA increased more dramatically than other species between 17：00 and 21：00 and peaked at noon, which could be related to cooking emissions. OOA, sulfate, nitrate, ammonium and chlo ride varied with the same trend. Their concentrations increased with solar radiation from 9：00 to 13：00, and declined with weakening solar radiation. Size distributions of all species showed apparent peaks in the range 500600 nm. Size distributions of organics were much broader than other species, particularly in autumn and winter. Distributions of sulfate, nitrate and am monium had similar patterns, broadening in winter. Contributions of different species were sizedependent; the finer the parti cle, the greater the contribution of organics. Organics represented more than 60% of particles smaller than 200 nm, contrib uting 50% to PM1 in winter. In spring and summer, HOA was the dominant organic fraction for particles smaller than 200 nm, while OOA contributed more to particles larger than 300 nm. In winter, HOA contributed more than OOA to all PM1 particles.

Measurement of aerosol effective density by single particle mass spectrometry

Single particle mass spectrometry has been widely used to determine the size and chemical compositions of at- mospheric aerosols; however, it is still rarely used for the microphysical properties measurement. In this study, two methods were developed for determining aerosol effective density by a single particle aerosol mass spectrometer （SPAMS）. Method I retrieved effective density through comparison between measured light scattering intensities and Mie theoretical modelled par- tial scattering cross section. Method Ⅱ coupled a differential mobility analyzer （DMA） with SPAMS to simultaneously deter- mine the electric mobility and vacuum aerodynamic diameter, and thus the effective density. Polystyrene latex spheres, ammo- nium sulfate and sodium nitrate were tested by these methods to help validate their effectiveness for determining the aerosol effective density. This study effectively extends SPAMS measurements to include particle size, chemical composition, light scattering, and effective density, and thus helps us better understand the environment and climate effects of aerosols.

Filtration of fine particles in atmospheric aerosol with electrospinning nanofibers and its size distribution

In this study, the size distribution of atmospheric aerosol in Beijing was monitored by the scanning mobility particle sizer spectrometer and the optical particle sizer. The size of particles in atmospheric aerosol was primarily distributed in the range of less than 1 pm. It showed different changes with the mass concentrations of particulate matters with an aerodynamic diameter of 〈2.5 pm （PM2.5） for different sizes of fine particles. The amount of ultrafine particles （less than about 60 nm） decreased while the larger ones （〉60 nm） increased along with the mass concentration of PM2.5 in atmospheric aerosol. This was be- cause of the formation of the secondary atmospheric aerosol. The polylactic acid （PLA） nanofibers were prepared for filtering the aerosol by electrospinning. PLA nanofiber mats were used as the middle layer to design the composite filter membranes. Atmospheric aerosol was used as dust source in the filtration test. The results showed that the filtration efficiency of the com- posite filter media increased along with the thickness of nanofiber mats, which was controlled by the collection time during electrospinning. Filtration efficiency can be improved obviously by compositing with a thin layer of nanofibers.