广州冬季PM10和PM2.5中有机碳与元素碳浓度水平及分布特征

于2002年1月至2月在广州市3个点采集不同粒径(PM2.5和PM10)大气气溶胶样品,测定了PM2.5,PM10及其中的有机碳(OC)和元素碳(EC)浓度,探讨了广州市冬季碳气溶胶的污染特征.结果表明,PM2 5和PM10平均浓度分别为105.9 μg/m3及161.7 μg/m3,其中PM25中的OC,EC浓度分别为22.6μg/m3和8.3μg/m3,PM10中的OC,EC浓度分别为29.4和10.4 μg/m3.PM2.5和PM10的总碳气溶胶含量分别为40.5%和35.7%.PM2.5和PM10中OC/EC的比值平均为2.7,这与大多数城市大气的OC/EC比值接近.OC与EC的相关性很好(R＞0.9),表明OC与EC的排放源相同.估算的PM2.5中次生有机碳(SOC)平均浓度为12.1μg/m3,占PM2.5中总OC浓度的49.6%;PM10的SOC平均浓度为14.3 μg/m3,占PM10中总OC的44.8%.     

Comparison of Sampling Methods for Carbonaceous Aerosols in Ambient Air

Measurement methods for fine particle carbon were compared under field sampling conditions. Sampling methods included filtration, impaction, and adsorption-corrected filtration. Systems were operated side-by-side for nine consecutive days in the Los Angeles Basin. Analytical methods were compared separately. For organic carbon and total carbon, ambient measurements showed greater variability than could be accounted for by differences in analytical methods, and these differences are attributed to sampling methodology. The highest reported concentrations were obtained by quartz filter sampling; the lowest were from the sum of the impactor stages (excluding the quartz afterfilters). Positive artifact from the adsorption of gaseous vapors on quartz fiber filters was significant. However, correction for vapor adsorption by subtraction of the carbon value on the second of two filters in series did not completely eliminate the dependence of the apparent total aerosol carbon concentration on filter face velocity or sample duration     

Variability of Particle Number,Black Carbon,and PM10, PM2.5, and PM1 Levels and Speciation: Influence of Road Traffic Emissions on Urban Air Quality

Measurements of particle number concentration (N), black carbon (BC), and PM ₁₀ , PM _2.5 , and PM ₁ levels and speciation were carried out at an urban background monitoring site in Barcelona. Daily variability of all aerosol monitoring parameters was highly influenced by road traffic emissions and meteorology. The levels of N, BC, PM _X , CO, NO, and NO ₂ increased during traffic rush hours, reflecting exhaust, and non-exhaust traffic emissions and then decreased by the effect of breezes and the reduction of traffic intensity. PM _2.5–10 levels did not decrease during the day as a result of dust resuspension by traffic and wind. N showed a second peak, registered in the afternoon and parallel to O ₃ levels and solar radiation intensity, that may be attributed to photochemical nucleation of precursor gases. An increasing trend was observed for PM ₁ levels from 1999 to 2006, related to the increase in the traffic flow and the diesel fleet in Barcelona. PM composition was highly influenced by road traffic emissions, with exhaust emissions being an important source of PM ₁ and dust resuspension processes of PM _2.5–10 , respectively.     

Spatio-temporal variability in atmospheric abundances of EC,OC and WSOC over Northern India

The atmospheric abundances of elemental carbon (EC), organic carbon (OC) and water-soluble organic carbon (WSOC) have been measured in aerosol samples collected during wintertime (December–March) from selected sites (urban, rural and high-altitude) in northern India. A characteristic feature of their abundance pattern, at urban sites, is reflected in the OC/EC ratios (range: 2.4–14.5, Av=7.8±2.4, n=77) indicating dominant contribution from biomass burning sources (wood-fuel and agriculture waste). This is in sharp contrast to the OC/EC ratios at a rural site (range: 2.1–4.0, Av=3.1±0.6, n=7) influenced by emissions from coal-fired industries. The long-term measurements made from a high-altitude site (～2000 m amsl) reveal significantly lower abundances of EC and OC; suggesting that boundary layer dynamics (during wintertime) play an important role in efficient trapping of pollutants within the Indo-Gangetic Plain (northern India). The WSOC/OC ratios are fairly uniform (～0.35) in aerosols over urban sites but relatively enhanced contribution of WSOC and higher ratios (～0.5) at a high-altitude site emphasizes the significance of secondary organic aerosols. The comprehensive data set on EC, OC and WSOC/OC ratios from northern India is crucial to improve model parameterization of carbonaceous aerosols for atmospheric scattering and absorption of solar radiation on a regional scale.     

Comparison of Measured Particle Lung-Deposited Surface Area Concentrations by an Aerotrak 9000 Using Size Distribution Measurements for a Range of Combustion Aerosols

Surface area in addition to mass concentration is increasingly being emphasized as an important metric representing potential adverse health effects from exposure to inhaled particles. Lung-deposited surface area (SA) concentrations for a variety of aerosols: coal, biomass, cigarette, incense, candle, and TiO₂ were measured using an AeroTrak 9000 (TSI Incorporated) and compared with those calculated from number size distributions from a scanning mobility particle sizer (SMPS). Three methodologies to compute the SA concentrations using the International Commission on Radiological Protection's (ICRP) Lung Deposition model and an SMPS were compared. The first method calculated the SA from SMPS size distributions, while the second method used lognormal size distribution functions. A third method generated a closed-form equation using the method of moments. All calculated SMPS SA data against which the measured SA data were compared were generated using the first method only; however, the SA concentrations calculated from each of the three methods demonstrated strong correlations with each other. Overall, results between measured and calculated lung-deposited SA indicated strong positive linear associations (R ² 0.78 - >0.99), moderately dependent on the type of aerosol. In all cases, the measured SA concentrations slightly underestimated those calculated from the SMPS data, with the exception of coal combustion particles. Although some dependency on aerosol material exists, the instrument measuring lung-deposited SA demonstrated consistent reliability across a range of concentrations for a range of materials. For optimal results however, applying a correction factor (CF) before taking the instrument to the field is recommended.

Copyright 2013 American Association for Aerosol Research     

Quantification of Hourly Speciated Organic Compounds in Atmospheric Aerosols,Measured by an In-Situ Thermal Desorption Aerosol Gas Chromatograph (TAG)

The Thermal desorption Aerosol Gas chromatograph (TAG) is a recently developed instrument for the in-situ, hourly measurement of speciated organic compounds in atmospheric aerosols. This paper presents a method for the in-field calibration of this instrument, with the objective of providing quantitative concentrations for a large suite of low polarity organic compounds. A new collection and thermal desorption cell was developed that incorporates an injection port for in-situ calibrations with liquid standard mixtures. Two classes of injection standards, instrument tracking and auxiliary, provide the means to calibrate the instrument in the field for a wide range of compounds. A routinely injected tracking standard suite of compounds generates a time-dependent correction of detector drift through the course of a measurement study that accounts for the bulk of the change in response of the TAG instrument. Injection response data for the tracking standard is also used to measure instrument precision and limits of quantitation. Auxiliary standards extend the range of compounds calibrated through use of relative response factors. The accuracy of this in-situ calibration approach is assessed through comparisons of TAG analyzed reference filter punches to published NIST assay values. A subset of compound classes, alkanes and PAHs, are used to illustrate the method and provide a means of reducing an 11-day period of data collected in Riverside, CA during the fall of 2005.     

Reconstructing Primary and Secondary Components of PM2.5 Composition for an Urban Atmosphere

Total 360 samples (of 8 h each) of PM_2.5 were collected from six sampling sites for summer and winter seasons in Kanpur city, India. The collected PM_2.5 mass was subjected to chemical speciation for: (1) ionic species (NH⁺ ₄, SO^2– ₄, NO^– ₃, and Cl^–), (2) carbon contents (EC and OC), and (3) elemental contents (Ca, Mg, Na, K, Al, Si, Fe, Ti, Mn, V, Cr, Ni, Zn, Cd, Pb, Cu, As, and Se). Primary and secondary components of PM_2.5 were assessed from speciation results. The influence of marine source to PM_2.5 was negligible, whereas the contribution of crustal dust was significant (10% in summer and 7% in winter). A mass reconstruction approach for PM_2.5 could distinctly establish primary and secondary components of measured PM_2.5 as: (1) Primary component (27% in summer and 24% in winter): crustal, elemental carbon, and organic mass, (2) Secondary component (45% in summer and 50% in winter): inorganic and organic mass, and (3) others: unidentified mass (27% in summer and 26% in winter). The secondary inorganic component was about 34% in summer (NH⁺ ₄: 9%; SO^2– ₄: 16%; NO^– ₃: 9%) and 32% in winter (NH⁺ ₄: 8%; SO²⁺ ₄: 13%; NO^– ₃: 11%). The secondary organic component was 12% in summer and 18% in winter. In conclusion, secondary aerosol formation (inorganic and organic) accounted for significant mass of PM _2.5 (about 50%) and any particulate control strategy should also include control of primary precursor gases.     

Effect of Aerosol Generation Method on Measured Saturation Pressure and Enthalpy of Vaporization for Dicarboxylic Acid Aerosols

To date, most studies of the thermodynamic properties of organic aerosols have utilized test aerosols generated by spray atomization followed by a diffusion drying step. Some evidence points to possible biases in measured thermodynamic properties stemming from the presence of residual solvent (water or alcohol) in the dried aerosol. In the current study we compared measurements of thermodynamic properties of organic aerosols generated by atomization of aqueous solutions to those generated by homogeneous condensation using a modified Sinclair-La Mer generator. In particular, using the Integrated Volume Method (Saleh et al. 2008 Saleh, R., Walker, J. and Khlystov, A. 2008. Determination of Saturation Pressure and Enthalpy of Vaporization of Semi-Volatile Aerosols: The Integrated Volume Method. J. Aerosol Sci., 39: 876[Crossref], [Web of Science ®] , [Google Scholar]), we measured and compared the saturation pressure (P _sat ) at 298 K and enthalpy of vaporization (ΔH) of C-6 (adipic) and C-9 (azelaic) dicarboxylic acid aerosol generated using these techniques. We found that P _sat and ΔH exhibited no statistically significant difference across the tested aerosol generation methods, indicating that any residual solvent carried by the particles had no impact on the measurements. For adipic acid, we obtained P _sat of 3.3 × 10^?5 (±0.9 × 10^?5) Pa and ΔH of 132 (±8) kJ/mol with atomization, and P _sat of 4.2 × 10^{? 5} (±2.2 × 10^?5) Pa and ΔH of 126 (±21) kJ/mol with homogeneous condensation; for azelaic acid, we obtained P _sat of 1.4 × 10^?5 (±0.5 × 10^?5) Pa and ΔH of 145 (±15) kJ/mol with atomization, and P _sat of 0.9 × 10^{? 5} (±0.3 × 10^{? 5}) Pa and ΔH of 158 (±17) kJ/mol with homogeneous condensation. In addition, SEM images of the acids generated by the two methods showed no obvious difference in surface morphology.     

Design,Calibration, and Field Test of a Cyclone for PM 1 Ambient Air Sampling

Ambient air sampling at a flow rate of 16.7 Lpm (1 m 3 /h) has been well established with the adoption, within the USA, of the EPA regulations governing PM 2.5 sampling. Subsequent to the adoption of the new regulation, problems were encountered with the impactor technique utilized for establishing a PM 2.5 cut ( D 50 = 2.5 w m aerodynamic equivalent diameter, A.E.D.). In order to avoid the depression in the cut point engendered by a buildup of collected material on the impactor stage and to extend the operating interval between cleanings, a cyclone was developed to replace the impactor. Although not an adopted standard, PM 1 has a practical appeal in that it represents the smallest cut point that can practically be assessed for long periods of time at high flow rates utilizing inertial techniques. Further relevance is attributed to this cut by interest in particulate matter related to diesel engine emissions. A new version of the sharp cut cyclone (SCC) was constructed with the aim of obtaining a cut point at D 50 = 1 w m at a flow rate of 16.7 Lpm. The dimensions of the cyclone were calculated using the SCC design model by Kenny and Gussman. Field studies were conducted to validate the PM 1 cyclone and to compare the results to colocated PM 10 and PM 2.5 concentration measurements.     

采暖期北京大气PM10水溶性离子成分分析研究

本文利用大气细粒子的快速捕集及化学成分在线分析系统、离子色谱、RP1400a,研究了北京大气2004年1月3～12日可溶性PM10气溶胶颗粒中阴阳离子的组分和浓度变化范围、以及PM10在北京大气中的质量浓度,结果表明北京大气PM10中可溶性阴离子主要有Cl-,NO2-,NO3-,SO42-组成,阳离子主要有Na+,NH4+,K+,Ga2+,Mg2+组成.Cl-,NO3-,SO42-的变化趋势有较好的一致性,NO2-的变辐不大,浓度比较稳定,SO42-的组分最高.阳离子除NH4+外平均浓度都低于2 ug/m3,NH4+浓度的日变化趋势与NO3-和SO42-浓度变化趋势具有一致性.北京大气PM10浓度偏高,空气污染严重.     

Light Degrading Properties of Size-Fractionated PM 10 Aerosol Samples Collected from an Industrial Area in Brisbane,Australia

Thirty-seven days of PM 10 aerosol samples (particles with aerodynamic diameter <10 w m) were collected in an industrial area in Brisbane during April to June 1999 to study the light extinction efficiencies of urban aerosols in different size ranges. The light scattering coefficient of the air was measured by nephelometry. The light absorption coefficient of the aerosol samples was measured by the integrating plate laser absorption method. Multiple linear regression techniques were used to investigate the relationships between the visibility degrading properties and the chemical composition of the aerosol samples. The results are comparable with those from other visual air quality studies. The absorption of light by fine (PM 2.5 ) aerosols is mainly due to elemental carbon (EC) particles smaller than 0.5 w m. The b 0 ap values of EC particles in different size ranges are 9.08 (< 2.7 w m) and 0.32 (2.7-10 w m)m 2 g -1 , respectively. The absorption of light by coarse (PM 2.5-10 ) aerosols is mainly due to soil ( b 0 ap = 0.17) and organic ( b 0 ap = 1.11) particles. The scattering of light is highly related to the concentration of fine particles in the air (mass scattering efficiency b 0 sp = 1.65) and is mainly due to the fine sulphate ( b 0 sp = 10.9), soil ( b 0 sp = 2.73), and EC ( b 0 sp = 3.89) particles. On average, fine EC (44%), sulphate (20%) and soil (7%) particles, NO 2 (9%), and Rayleigh scattering (19%) were the largest contributors of visibility degradation for the sampling days in this study.     

Characterization of Single Particles in Urban Atmospheric Aerosols Over Nagoya Based on Mass Spectral Analysis

Mass spectral analysis of single aerosol particles was performed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) in the urban area of Nagoya, Japan, for five days in the autumn of 2010. An ion-series analysis was applied to the single-particle mass spectra; the sum of the masses at Δ of 1, 3, 4, and 5 divided by the total mass of organics (f_Δ1,3-5) was used as an indicator of the degree of oxygenation of the organics. The organic mass fraction (F_org) and f_Δ1,3-5 of single particles varied substantially, and the results for the entire period indicate that two groups of particles with high and low f_Δ1,3-5 were present. The organics in particles with high F_org were less oxygenated, whereas those with low F_org were more oxygenated; these different particles were associated with hydrocarbon-like organic aerosols (HOA) and low-volatility oxygenated organic aerosols (LV-OOA), respectively, based on the PMF analysis of the MS mode data. The size distributions of the two types of particles overlapped substantially. The degree of the overlap depends on the equivalent particle diameter used, indicating the importance of single-particle analysis in understanding the size-composition relationship in detail. Alteration of the aerosol mixing state was clearly indicated by the changes in f_Δ1,3-5 and F_org; the homogeneous conditions changed to externally mixed conditions from the evening until noon of the next day. Possible causes of this alteration include the condensation of oxygenated organics and ammonium nitrate onto pre-existing particles. This study demonstrated the usefulness of single-particle analysis based on electron-ionization aerosol mass spectrometry.

Copyright 2015 American Association for Aerosol Research     

关于环境空气连续采样过程影响因素的探讨

以SO2采样为例对影响环境空气连续采样过程的有关影响因素进行了探讨,分析了影响监测结果的一些原因或可能。强调空气连续监测质量保证工作的重点要从实验室环节转到现场采样等环节上来。     

冬季重庆市主城区PM_(2.5)时空分布特征研究

利用2014年12月1日至2015年2月28日重庆市主城区17个国控点PM2.5的在线监测数据分析重庆市主城区冬季PM2.5的时间分布特征和空间分布特征。结果表明,冬季重庆市主城区周三PM2.5浓度最低,周六周日浓度最高;日变化趋势呈现两峰两谷,两峰分别出现在12时和21时,两谷出现在7时和16时,夜晚21时浓度最高,上午7时浓度最低;主城区东北部和西南部PM2.5浓度较高,西北和东南部浓度低。     

南充市车流量对城市空气质量的影响分析

根据南充市城区SO2、NO2、PM10和PM2.5小时浓度数据,结合四种主要交通方式的车流量,分析车流量与空气质量相关性及其影响。结果表明,南充市城区每日车流量变化趋势呈现"四峰"现象,在08:00-09:00、11:00-12:00和14:00-15:00三个时段分别达到2650、2360和2677辆,第四个峰值可能在19:00或者之后;车流量以私家车和出租车为主,分别占总车流量的45%±4%和26%±3%。SO2、NO2质量浓度值基本稳定,为0.020 mg/m3左右,PM10和PM2.5的日平均浓度随日平均车流量变化比较明显,机动车流量对PM10、NO2的影响比SO2、PM2.5大。     

PM 1 , Intermodal (PM 2.5-1 ) Mass,and the Soil Component of PM 2.5 in Phoenix,AZ, 1995-1996

Concentrations of size-resolved airborne particulate matter measured in Phoenix, Arizona in 1995-1996 indicate a strong linear relationship between the soil components of PM 2.5 and the intermodal PM concentration and similarly between the nonsoil components of PM 2.5 and the PM 1 concentration. Moreover, the ratio of PM 1 to intermodal PM varies considerably at all reported concentrations of PM 2.5 , and this variation appears to be systematically related to the proportion of PM 2.5 comprised of soil components.     

哈尔滨市大气中TSP、PM_(10)和PM_(2.5)相关性分析

对哈尔滨市大气环境中的TSP、PM10、PM2.5进行了采集和质量浓度的分析。实验结果表明:细颗粒(PM2.5)所占比例全年变化比较明显,1月、10月、11月和12月含量较高,均占到总量的55%以上,同时PM2.5/PM10也处于全年最高值,说明此期间细颗粒污染较为严重,环境危害较大;PM10含量全年变化相对稳定,PM10/TSP变化幅度仅为0.71~0.79,说明全年颗粒物质量分布的变化主要由PM2.5和PM2.5-10引起。根据TSP和PM10、PM10和PM2.5之间的相对关系曲线可以看出,两种大气颗粒物均来自相似的污染源,且污染源排放大气颗粒物的粒度分布长期比较稳定,而PM10和PM2.5的相关系数R值为0.973,也具备一定的相关性,可认为两者的变化趋势是一致的。     

城市住宅小区再生水的利用分析

城市住宅小区再生水利用是水污染防治和节水的重要途径。本文对城市住宅小区再生水利用特点、工艺技术、利用途径和方式、存在问题等进行了初步探讨,就城市住宅小区再生水利用在技术使用、运营管理等方面的问题提出相应建议。