基于MODIS AOD数据的南京市大气能见度估算

以南京市为研究区,利用MODIS气溶胶产品数据(MOD04L2)获取研究区气溶胶标高数据,结合地面气象站点能见度观测数据,构建研究区不同季节能见度估算模型,估算南京市2013年能见度时空分布。研究结果表明,研究区能见度模型估算值与实测值总体趋势较为一致,分季节模型能见度估算均值相对误差为14.3%;南京市2013年能见度年均值为6.07km,大致呈现出由市区向周边郊区逐渐升高的趋势;研究区不同季节能见度差异明显,夏季能见度显著高于其他3个季节,在该季节全市能见度均值达到9.93km,约为其余3个季节均值的2倍左右,气候状况与经济社会发展布局是影响研究区能见度时空差异的主要因素。     

Measurement of particulate aliphatic and polynuclear aromatic hydrocarbons in Santiago de Chile: source reconciliation and evaluation of sampling artifacts

Using a novel sampler, particulate organic compounds were collected in Santiago de Chile from June 9 to August 10, 1997. This sampler consists of a diffusion denuder to remove gas-phase organics prior to particle collection, a Teflon filter, and a PUF cartridge downstream of the filter. PAHs and n-alkanes were measured using gas chromatography/mass spectrometry analysis. Volatilization of particles collected on the Teflon filter varied from 15 to 85% for both n-alkanes and PAHs, with strong dependence on molecular weight. The relative distribution of n-alkanes and the values of molecular diagnostic ratios, such as Carbon preference index, indicated a mixed origin with strong anthropogenic input. Indeed, CPI values ranged from 0.66 to 1.96 (for the whole range of n-alkanes). The percent contribution of leaf “wax” n-alkanes (4.55–20.83%) indicated the low contribution of biogenic sources. In addition, the distribution pattern of PAHs was characteristic of anthropogenic emissions. The dominant contribution of combustion-related PAHs (CPAHs), 74–84%, indicated that vehicular emissions was the major source of PAHs.     

Reduction of sampling and analytical errors for electron microscopic analysis of atmospheric aerosols

Electron microscopy-energy dispersive spectroscopy (EM/EDS) can be used to determine the elemental composition of individual particles. However, the accuracy with which atmospheric particle compositions can be quantitatively determined is not well understood. In this work we explore sources of sampling and analytical bias and methods of reducing bias. Sulfuric acid [H₂SO₄] and ammonium sulfate [(NH₄)₂SO₄] particles were collected on beryllium, silicon, and carbon substrates with similar deposition densities. While [(NH₄)₂SO₄] particles were observed on all substrates, [H₂SO₄] and ammonia-treated [H₂SO₄] particles could not be found on beryllium substrates. Interactions between the substrate and sulfuric acid particles are implicated. When measured with EM/EDS, [H₂SO₄] particles exposed to ammonia overnight were found having lower beam damage rates (0.000 ± 0.002 fraction s⁻¹) than those without any treatment (0.023 ± 0.006 fraction s⁻¹) For laboratory-generated [C₁₀H₆(SO₃Na)₂] particles, the composition determined using the experimental k-factors evaluated from independent particle standards of similar composition and size shows an error less than 20% for all constituents, while greater than 78% errors were found when k-factors were calculated from the theory. This study suggests (1) that sulfate beam damage can be reduced by exposure of atmospheric particle samples to ammonia before analysis, (2) that beryllium is not a suitable substrate for atmospheric particle analysis, and (3) calibration (k-factor determination) using particle standards of similar size and composition to particles present in the atmosphere shows promise as a way of improving the accuracy of quantitative EM analysis.     

北京西三环地区大气颗粒物中多环芳烃的分布

2012年3-8月对北京西三环地区大气颗粒物进行分级采样,利用气相色谱(GC)/质谱(MS)联用仪对颗粒物中多环芳烃(PAHs)含量进行测定.结果表明,检出的16种PAHs总质量浓度(∑16PAHs)平均为46.73ng/m3;苯并[a]蒽(BaA)等6种单体浓度与∑16PAHs呈良好线性关系;PAHs粒径分布特征表明,其更易富集在细颗粒物上;不同环数PAHs分布特征为:3环＞4环＞5环＞6环＞2环,随着颗粒粒径减小,高环数PAHs含量增加.温度、湿度和紫外线(UV)指数与∑16PAHs呈负相关.通过特征化合物比值分析法对PAHs进行源解析发现,采样期间PAHs主要来源为燃烧源,交通源影响微弱.     

Gas and Aerosol Loadings at Holme Moss 1996–1998 Measurements and Analysis Using Back-Trajectory Clustering

A continuous two-year atmospheric datasetcomprising gas and aerosol loadings from amountain site in northern England (Holme Moss,W1°5130 N53°320) is presented. The data are analysed with respect to three-dayback-trajectories that are grouped according to aclustering technique that allows speed, directionand curvature of the airmass track to beconsidered. The technique is successful inseparating the data into chemically distinctsubsets. Up to 29% of the variance in the datais explained by back-trajectory clusters. Slow trajectories are associated with highloadings especially for the oxides of nitrogen,which may imply a local source for much of thesuspended pollutant. The data suggest thatproduction of nitrate and sulphate is limited byoxidant availability at least in the winter. Itmay be possible to optimise the analytical powerof the technique by increasing the importance ofrecent airmass track in determining clusterallocation. This applies especially to the totalsulphur loading.     

Identification,Abundance and Origin of Aliphatic Hydrocarbons in the Fine Atmospheric Particulate Matter of Athens,Greece

The organic chemical composition of the fine fraction of atmospheric particulate matter in Athens has been studied, in order to establish emission sources. The results of the analyses of the aliphatic fraction indicate that all samples contain n-alkanes ranging from C₁₄ to C₃₂, with C₂₅, C₂₆, C₂₇ and C₂₉ being the more abundant congeners. Fossil fuels biomarkers such as extended tricyclic terpanes (hopanes, steranes) and isoprenoid hydrocarbons (pristane, phytane) were observed in our samples on a daily basis. Source reconciliation was conducted using molecular diagnostic ratios (such as the carbon preference index – CPI). The mean CPI value (1.84) indicates the mixed origin of the Athenian fine particles. The notable presence of an unresolved complex mixture or “hump” of hydrocarbons in our gas chromatograms is indicative of petrogenic hydrocarbon inputs. An approximate measure of this kind of contamination is the ratio of the concentrations of unresolved components to the resolved n-alkanes and other major compounds (U:R). The high U:R value of 25.25 further confirmed the major contribution of fossil fuels. Yet, the percent contribution of leaf wax n-alkanes (25.15%) indicated the parallel contribution of biogenic sources. This work supports the conclusion that vehicular emissions were the major source of aliphatic organic compounds with a smaller contribution of biogenic n-alkanes during the study period in Athens.     

ICAROS: An Integrated Computational Environment for the Assimilation of Environmental Data and Models for Urban and Regional Air Quality

Integrated environmental management in urban areas is nowadaysconsidered a sine qua non objective of Community and nationalenvironmental and development policies. A large amount ofscientific information on the state of the environment is nowavailable from a large pool of data sources. This work presentsan innovative method for integration of these data sources andeffective coupling of environmental information with appropriatemodels and decision-support tools. State-of-the-art Earthobservation techniques, ground-based air quality measurements,atmospheric transport and chemical modelling, and multi-criteriadecision-aid systems are used in an integrated information fusionenvironment in support of environmental and health impactassessment and decision-making at the urban and regional scales. Results of the pilot application of the method in the area ofLombardy in Northern Italy demonstrate the validity andusefulness of this novel approach.     

二氧化钛气溶胶颗粒在石英玻璃纤维上的沉积

利用雾化挥发发生原理制备二氧化钛气溶胶,将二氧化钛气溶胶颗粒负载在石英玻璃纤维上,制备二氧化钛-石英玻璃纤维功能性空气过滤材料。实验研究了二氧化钛气溶胶发生相关参数、石英玻璃纤维直径分布、透过率曲线、最易透过粒径,并对二氧化钛气溶胶颗粒在石英玻璃纤维上的负载过程和负载形态进行了探讨。研究结果表明,发生的二氧化钛气溶胶具有可控的粒径分布和较好的分散性;中值粒径128 nm的二氧化钛气溶胶颗粒能够稳定负载在3 μm的石英玻璃纤维上;二氧化钛在石英玻璃纤维上的沉积量受沉积时间的影响,沉积过程中阻力开始变化不大,随后在沉积饱和点后阻力迅速增大,滤料填充度越高沉积饱和点出现时间越早;二氧化钛粒子在纤维表面的负载形态除颗粒、团簇外,还有三维的树枝状空间结构。     

锂离子电池电解液火灾的烟雾探测方法研究

基于散射不对称比的气溶胶识别方法,采用单个入射波长和两个散射角的方式测定了电解液火灾、正庚烷火、棉绳阴燃三种火灾烟雾和D90粉尘的前后向散射不对称比.结果表明,在红外L ED光源作用下,前向散射角为45°和后向散射角为135°时,不同类型气溶胶的散射不对称比的均值和变化率存在差异,这可以用于区分火灾烟雾和干扰气溶胶.此...     

中国3个AERONET站点气溶胶大小的识别及特征分析

?ngstr?m波长指数a是判断气溶胶粒子大小的重要参数,但当气溶胶尺度分布不满足Junge分布时,仅用a不能很好的反映气溶胶粒子的尺度信息.利用Mie散射理论和AERONET站点实测资料分析说明在0.750.6;当a2>0.3时,多以粗粒子为主,Vfine/Vtotal<0.4.利用Gobbi气溶胶图解法分析显示SACOL站AOD的大值主要是由于沙尘气溶胶的影响造成的;香河站沙尘和细粒子气溶胶都会产生大值AOD,并且图解法可以很好的区分这两种情况;太湖站受沙尘的影响较小,大值AOD绝大多数是由于细粒子气溶胶造成的.