南京北郊气溶胶散射特性观测研究

南京北郊是重工业区,空气污染严重。该文利用浊度仪对大气气溶胶散射系数进行了四季观测,研究了该区气溶胶散射系数、后向散射比、质量散射系数及散射系数与能见度的关系,结果表明,观测期间散射系数波动较大,平均值为344.84 Mm^-1,标准差为215.99 Mm^-1,散射系数季节差异明显,主要受气象条件和外界污染排放的影响;后向散射比平均值为0.139,春季变化剧烈,夏、秋、冬季在波动中缓慢上升,大气中细粒子污染严重且含量有增加的趋势;散射系数与PM_2.5质量浓度相关系数达到0.91,质量散射系数平均值为1.87m²/g;散射系数与能见度之间存在-0.66的相关性,两者呈负幂函数关系。     

珠三角秋冬季节长时间灰霾污染特性与成因

利用珠三角大气超级站2012年10月与2013年1月能见度、不同粒径颗粒物与BC质量浓度、气溶胶光散射系数、O3、相对湿度等在线监测数据,分析秋冬季节2次持续时间超过10 d的长时间灰霾过程污染特性与成因。结果表明,冬季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为13%和67%;PM2.5、PM1占PM10质量浓度分别为66%和39%;较高的PM2.5与BC日均浓度相关系数(R2=0.88)体现了一次排放对颗粒物质量浓度及能见度的显著影响。秋季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为11%和69%,由BC导致的吸光效应较冬季下降了约20%;PM2.5和PM1占PM10质量浓度比例分别为68%和45%,均高于冬季;O3浓度日最大小时值的平均值接近冬季的2倍;二次来源对PM2.5浓度升高和能见度下降起主导作用。来自不同方向的2种气团在珠三角僵持,大气扩散条件差是导致这2次灰霾过程的重要外在条件,应成为灰霾预报预警的重点关注对象。     

Distribution of PM2.5 and PM10-2.5 in PM10 Fraction in Ambient Air Due to Vehicular Pollution in Kolkata Megacity

This research paper aims at establishing baseline PM₁₀ and PM_2.5 concentration levels, which could be effectively used to develop and upgrade the standards in air pollution in developing countries. The relative contribution of fine fractions (PM_2.5) and coarser fractions (PM_10-2.5) to PM₁₀ fractions were investigates in a megacity which is overcrowded and congested due to lack of road network and deteriorated air quality because of vehicular pollution. The present study was carried out during the winter of 2002. The average 24h PM₁₀ concentration was 304 μg/m³, which is 3 times more than the Indian National Ambient Air Quality Standards (NAAQS) and higher PM₁₀ concentration was due to fine fraction (PM_2.5) released by vehicular exhaust. The 24h average PM_2.5 concentration was found 179 μg/m³, which is exceeded USEPA and EU standards of 65 and 50 μg/m³ respectively for the winter. India does not have any PM_2.5 standards. The 24 h average PM_10-2.5 concentrations were found 126 μg/m³. The PM_2.5 constituted more than 59% of PM₁₀ and whereas PM₁₀-PM_2.5 fractions constituted 41% of PM₁₀. The correlation between PM₁₀ and PM_2.5 was found higher as PM_2.5 comprised major proportion of PM₁₀ fractions contributed by vehicular emissions.     

超低排放下燃煤电厂颗粒物排放特征分析研究

选取6家经过超低排放改造的燃煤电厂,对湿法脱硫(WFGD)和湿式电除尘器(WESP)进出口烟气中TPM、PM_(10)、PM_(2.5)、PM_1进行测试,分析研究超低排放下燃煤电厂颗粒物的排放特征及电除尘器后净化设备对颗粒物的脱除效果。结果表明,6家电厂TPM、PM_(10)、PM_(2.5)、PM_1排放浓度分别为0.75~2.36、0.71~2.12、0.65~1.96、0.51~1.57 mg/m~3。分析烟气中颗粒物粒径分布可知,除尘器后,PM10占TPM质量比低于40%,且比例随烟气经过WFGD和WESP而逐渐降低。WFGD对PM2.5有较好的脱除效果,而WESP对PM1脱除效果显著。为满足超低排放标准,6家电厂除尘器后脱除设备综合除尘效率大多在85%以上。计算得到6家电厂TPM、PM_(10)、PM_(2.5)、PM_1排放因子,与超低排放改造之前同等级燃煤电厂相比,6家电厂不同粒径颗粒物排放因子均显著降低,也远低于西方发达国家燃煤电厂颗粒物排放因子。     

Indoor and outdoor PM mass and number concentrations at schools in the Athens area

Simultaneous indoor and outdoor PM₁₀ and PM_2.5 concentration measurements were conducted in seven primary schools in the Athens area. Both gravimetric samplers and continuous monitors were used. Filters were subsequently analyzed for anion species. Moreover ultrafine particles number concentration was monitored continuously indoors and outdoors. Mean 8-hr PM₁₀ concentration was measured equal to 229 ± 182 μg/m³ indoors and 166 ± 133 μg/m³ outdoors. The respective PM_2.5 concentrations were 82 ± 56 μg/m³ indoors and 56 ± 26 μg/m³ outdoors. Ultrafine particles 8-h mean number concentration was measured equal to 24,000 ± 17,900 particles/cm³ indoors and 32,000 ± 14,200 particles/cm³ outdoors. PM₁₀ outdoor concentrations exhibited a greater spatial variability than the corresponding PM_2.5 ones. I/O ratios were close or above 1.00 for PM₁₀ and PM_2.5 and smaller than 1.00 for ultrafine particles. Very high I/O ratios were observed when intense activities took place. The initial results of the chemical analysis showed that accounts for the 6.6 ± 3.5% of the PM₁₀ and for the 3.1 ± 1.4%.The corresponding results for PM_2.5 are 12.0 ± 7.7% for and 3.1 ± 1.9% for . PM_2.5 indoor concentrations were highly correlated with outdoor ones and the regression line had the largest slope and a very low intercept, indicative of no indoor sources of fine particulate . The results of the statistical analysis of indoor and outdoor concentration data support the use of as a proper surrogate for indoor PM of outdoor origin.     

PM2.5 and PM10 Concentrations from the Qalabotjha Low-Smoke Fuels Macro-Scale Experiment in South Africa

This article presents results from the particulate monitoringcampaign conducted at Qalabotjha in South Africa during the winter of 1997. Combustion of D-grade domestic coal and low-smoke fuels were compared in a residential neighborhood to evaluate the extent of air quality improvement by switchinghousehold cooking and heating fuels.Comparisons are drawn between the gravimetric results from the two types of filter substrates (Teflon-membrane and quartz-fiber) as well as between the integrated and continuous samplers. It is demonstrated that the quartz-fiber filters reported 5 to 10% greater particulate mass than the Teflon-membrane filters, mainly due to the adsorption of organic gases onto the quartz-fiber filters. Due to heating of sampling stream to 50 °C in the TEOM continuous sampler and the high volatile content of the samples, approximately 15% of the particulate mass was lost during sampling.The USEPA 24-hr PM_2.5 and PM₁₀ National Ambient Air Quality Standards (NAAQS) of 65 g m^-3 and 150 g m^-3, respectively, were exceeded on several occasions during the 30-day field campaign. Average PMconcentrations are highest when D-grade domestic coal was used, and lowest between day 11 and day 20 of the experiment when a majority of the low-smoke fuels were phased in. Source impacts from residential coal combustion are also found to be influenced by changes in meteorology, especially wind velocity.PM_2.5 and PM₁₀ mass, elements, water-soluble cations (sodium, potassium, and ammonium), anions (chloride, nitrate, and sulfate), as well as organic and elemental carbonwere measured on 15 selected days during the field campaign. PM_2.5 constituted more than 85% of PM₁₀ at three Qalabotjha residential sites, and more than 70% of PM₁₀ at the gradient site in the adjacent community of Villiers. Carbonaceous aerosol is by far the most abundant component, accounting for more than half of PM mass at the three Qalabotjha sites, and for more than a third of PM mass at the gradient site. Secondary aerosols such as sulfate, nitrate,and ammonium are also significant, constituting 8 to 12% of PM mass at the three Qalabotjha sites and 15 to 20% at the Villiers gradient site.     

Ambient Air Quality Status in Raniganj-Asansol Area, India

This investigation presents the assessment of ambient air quality with respect to suspended particulate matter (SPM), sulphur dioxide (SO₂) and oxides of nitrogen (NO_X) at four sites (RGC, SRS, BBC and BCC) in the Raniganj-Asansol area in West Bengal, India. Ambient air was monitored with a sampling frequency of twenty four hours (3 × 8 hours) at each site on every alternate day (3 days a week) covering a period of one year. A total of 429 samples were collected from RGC, 429 from SRS and 435 each from the BBC and BCC sites. Meteorological parameters such as temperature, relative humidity, wind-speed and wind-direction were also recorded simultaneously during the sampling period. Monthly and seasonal variation of these pollutants have been observed and recorded. The annual average and range values have also been calculated. Results of the investigation indicates that the 95th percentile values of SPM levels exceed the limits (200 g m^-3) at RGC, SRS and BBC sites and is within the limit of 500 g m^-3 at the BCC sites. The 95th percentile values of SO₂ levels did not exceed the reference level at any of the monitoring stations. The 95th percentile values of NO_X are found to be exceeding the limit (80 g m^-3) at RGC, SRS and BBC sites but is within the prescribed limit of 120 g m^-3 at the BCC site. Further, it has been observed that the concentrations of the pollutants are high in winter in comparison to the summer or the monsoon seasons. Results of the investigation indicates that industrial activities, indiscriminate open air burning of coal by the local inhabitants for cooking as well as coking purposes, vehicular traffic, etc. are responsible for the high concentration of pollutants in this area.     

Acidic and basic properties and buffer capacity of airborne particulate matter in an urban area of Beijing

Particles with aerodynamic diameters <10  $\upmu $ m (PM₁₀) and particles with aerodynamic diameters <2.5  $\upmu $ m (PM_2.5) were sampled during summer 2006 in Beijing and mass concentrations, water-soluble ionic compounds concentrations, and acidic buffer capacity were analyzed. Results show that the mass concentration ranges of PM₁₀ and PM_2.5 were from 56.4 to 226.6  $\upmu $ g/m³ and from 31.3 to 200.7  $\upmu $ g/m³ during sampling days, respectively. Concentrations of F^???, Cl^???, NO $_{3}^{\,\,-}$ , NO $_{2}^{\,\,-}$ , SO $_{4}^{\,\,2-}$ , Ac^???, Ca^2?+?, Na^?+?, K^?+?, Mg^2?+?, and NH $_{4}^{\,\,+}$ in particles were analyzed by ion chromatography. Microtitration was adapted to determine the acidic?Cbasic property and the change of the buffering systems in different pH of the aqueous solution in which the PM is suspended. The major alkalinity and buffer capacity of particles were analyzed and calculated. The average carbonate buffer capacity was 0.3 mmol/g in PM_2.5 and 0.7 mmol/g in PM₁₀. The average acetic acid buffer capacity was 0.1 mmol/g in PM_2.5 and 0.3 mmol/g in PM₁₀. Carbonate and acetic acid are the main species for the buffer capacity in the particle phase. The average mass of carbonate was 71.0 mg/g in PM₁₀ and 46.7 mg/g in PM_2.5. The average mass of acetic acid was 11.2 mg/g in PM_2.5 and 20.0 mg/g in PM₁₀.     

Air Pollution Concentrations of PM2.5, PM10 and NO2 at Ambient and Kerbsite and Their Correlation in Metro City – Mumbai

Ambient concentrations of PM_2.5 and PM₁₀ are of concern with respect to effects on human health and environment. Increased levels of mortality and morbidity have been associated with respirable particulate air pollution. In India, it is not yet mandatory to monitor PM_2.5 levels therefore very limited information is available on PM_2.5 levels. To understand the fine particle pollution and also correlate with PM₁₀ which are monitored regularly in compliance with ambient air quality standards. This study was carried out to monitor PM_2.5, PM₁₀, and NO₂ for about one year in a residential cum commercial area of Mumbai city with a view to understand their correlation. The average PM_2.5 concentration at ambient and Kerbsite was 43 and 69 μg/m³. The correlation coefficients between PM_2.5 and PM₁₀ at ambient and Kerbsite were 0.83 and 0.85 respectively thus indicating that most of the PM_2.5 and PM₁₀ are from similar sources. TSP, PM₁₀ levels exceeded Central Pollution Control Board(CPCB) standard during winter season. PM_2.5 levels also exceeded 24 hourly average USEPA standard during winter season indicating unhealthy air quality.     

南京市大气颗粒物中多环芳烃变化特征

逐月采集南京市大气中不同粒径的颗粒物,采用HPLC分析了2010年每个月PM_(10)和PM_(2.5)颗粒物样品中的多环芳烃(PAHs)的种类和浓度水平。结果表明:PM_(10)中PAHs年均值为25.07 ng/m~3,范围为11.03~53.56 ng/m3;PM_(2.5)中PAHs年均值为19.04 ng/m~3,范围为10.82~36.43 ng/m~3。PM_(10)和PM_(2.5)中PAHs总体浓度有着相似的变化趋势,呈现凹形变化曲线;在南京市大气颗粒物中吸附的PAHs大部分以5~6环的高环数组分为主,大部分PAHs和∑PAHs的相关性较好,年度变化幅度不大,分析结果表明,颗粒物中PAHs的来源与稳定的排放源相关,机动车排放不容忽视,与北方城市燃煤污染有着较大的区别。     

基于灰关联分析的天津市气溶胶消光特征研究

根据天津市秋季(2006年10月10日～20日)消光系数(bext)、PM2.5、SO2、NOX、NO2、O3质量浓度及相对湿度监测结果,利用灰色关联分析法分析大气消光系数同空气中的几种主要污染要素的相关性。结果表明,与消光系数有关的几种主要指标的灰关联度序为PM2.5NOXRHNO2O3,其中PM2.5与消光系数的灰关联系数达到0.905,远高于其他相关指标。同时对PM2.5和消光系数相关分析表明,监测期间天津市PM2.5质量消光系数为6.04m2/g。     

广州市春季一次沙尘天气过程综合观测

2017年4月21—23日广州市经历了一次远距离传输的沙尘天气过程,为了解沙尘过程对广州市空气质量的影响,基于广州市大气超级站,利用单颗粒气溶胶质谱(SPAMS)、气溶胶激光雷达观测数据并结合HYSPLIT后向轨迹模型分析了沙尘过程细颗粒物组分及污染来源贡献变化和沙尘气溶胶的来源及路径。结果表明:受沙尘过境影响,PM_(10)浓度大幅升高,PM_(2.5)/PM_(10)最小值仅为12.1%;沙尘过境期间影响近地面颗粒物的沙尘高度主要分布在1 km以下区域,近地面颗粒物消光系数均值为100.11 Mm~(-1),探测到最大退偏振比为0.28。SPAMS研究发现沙尘过境期间含硅酸盐颗粒物(SI)的细颗粒物数浓度比例达25.9%,是沙尘过境前的1.4倍;PM_(2.5)中扬尘贡献率明显增大,达到了17.3%,是沙尘过境前的1.9倍。后向轨迹模型HYSPLIT显示此次沙尘为典型的北方沙尘传输,沙尘源自中国西北地区,传输方向为自西北输送至华东地区后,转为东南方向影响广州市。     

大同市大气颗粒物浓度与水溶性离子季度分布特征

为研究大同市大气颗粒物质量浓度与水溶性离子组成特征,于2013年2、7、9、12月,分别对大同市及其对照点庞泉沟国家大气背景点进行了PM2.5及PM10的采样,通过超声萃取-IC法测定了样品中的9种水溶性离子,结果表明,大同市大气颗粒物污染1、4季度重于2、3季度,PM2.5季度均值全年均未超标,PM10仅第1季度超标1.4倍,污染状况总体良好,PM2.5与PM10相关系数R为0.75,说明大同市颗粒物污染有较为相近的来源,且不同季节均以粗颗粒物为主;大同市PM2.5中水溶性离子浓度分布为SO2-4、NO-3、NH+4Cl-、Ca2+K+、Na+F-、Mg2+,PM10中Ca2+浓度仅次于SO2-4、NO-3,控制扬尘将有效降低PM10的浓度;PM2.5及PM10中的9种水溶性离子在不同季度的浓度与颗粒物浓度分布规律类似,1、4季度较高,2、3季度较低;由阴阳离子平衡计算结果可知,相关性方程的斜率K为1.045,表明大同市大气颗粒物中阳离子相对亏损,大气细粒子组分偏酸性。NO-3与SO2-4浓度比值均小于1,大同市以硫酸型污染为主,大气中的SO2-4主要来源于人类活动排放。     

Effect of Common Pesticides Used in the Niger Delta Basin of Southern Nigeria on Soil Microbial Populations

The effects of eleven pesticides on the populations of bacteria, actinomycetes, fungi and protozoa was investigated by treating a garden soil with their recommended rates. The microbial populations were estimated using the standard plate-count technique. Of the ll pesticides investigated, phenylmercuric acetate (agrosan) at 50 g g^-1 inhibited bacterial density the most, i.e. from 4,600,000 to 220 cells g^-1. The pesticides were Pentachloronitrobenzene (PCNB), tetramethylmethylthiuram disulphide (thiram),1- naphthylmethylcarbamate (Vetox 85), 1,2,3,4,5,6-hexachlorocyclohexane (Gammalin 20), phenylmercuric acetate (Agrosan), tetrachloroterephthalic acid (Dacthal), 4-nitrophenyl –2-nitro-4-trifluoromethylphenyl ether (Preforan), 2-ethyl-6-methyl –N-2-methoxy –1-methyl ethyl-chloroacetanide (Dual), Benlate, Brestan and Gramoxone. Pentachloronitrobenzene (PCNB) at 240,000 g g^-1 reduced bacterial population from 4,600,000 to 2,100 cells g^-1, whereas tetramethylthiuram disulphide (thiram) at 100 g g^-1 suppressed it by 2 log orders of magnitude. Soil application of 1-naphthylmethylcarbamate (Vetox 85) at 100 g g^-1 and 1,2,3,4,5,6,-hexachlorocyclohexane (Gamalin 20) at 1,300 g g^-1 repressed the bacterial numbers by 2 log orders of magnitude each. Pentachloronitrobenzene reduced the actinomycetes density from 340,000 to 320 cells g^-1 and completely eliminated all fungal and protozoan propagules from the soil. The Gammalin 20 completely wiped out all the fungi, whereas phenylmercuric acetate totally eliminated all the protozoa and reduced the fungal population from 34,000 to 60 cells g^-1. In general, protozoa and fungi were more susceptible to fungicides than bacteria and actinomycetes. Pentachloronitrobenzene, 1,2,3,4,5,6,-hexachlorocyclohexane and phenylmercuric acetate were toxic particularly to soil microorganisms, whereas the herbicides dacthal, Preforan and Dual were quite harmless in soil at application rates of 0.1, 0.06 and 0.02 g g^-1 respectively.     

Specific absorption and backscattering coefficients of the main water constituents in Poyang Lake, China

Obtaining and analyzing the specific inherent optical properties (SIOPs) of water bodies is necessary for bio-optical model development and remote sensing-based water quality retrievals and, further, for related ecological studies of aquatic ecosystems. This study aimed to measure and analyze the specific absorption and backscattering coefficients of the main water constituents in Poyang Lake, China. The specific absorption and/or backscattering coefficients of the main water constituents at 85 sampling sites (47 in 2010 and 38 in 2011) were measured and analyzed as follows: (1) the concentrations of chlorophyll a (C _CHL), suspended particulate matter (C _SPM) (including suspended particulate inorganic matter (C _SPIM) and suspended particulate organic matter (C _SPOM)), and the absorption coefficients of total particulate (a _p), phytoplankton (a _ph), and non-pigment particulate (a _d) were measured in the laboratory; (2) the total backscattering coefficients at six wavelengths of 420, 442, 470, 510, 590, and 700 nm, including the contribution of pure water, were measured in the field with a HydroScat-6 backscattering sensor, and the backscattering coefficients without the contribution of pure water (b _b) were then derived by subtracting the backscattering coefficients of pure water from the total backscattering coefficients; (3) the specific absorption coefficients of total particulate ( $ a_{\mathrm{p}}^{ * } $ ), phytoplankton ( $ {a_{{\mathrm{ph}}}}^{ * } $ ), and non-pigment particulate ( $ a_{\mathrm{d}}^{ * } $ ) were calculated by dividing a _p, a _ph, and a _d by C _SPM, C _CHL, and C _SPIM, respectively, while the specific backscattering coefficients of total suspended particulate matter ( $ b_{\mathrm{b}}^{ * } $ ) were calculated by dividing b _b by C _SPM; and (4) the $ {a_{{\mathrm{ph}}}}^{ * } $ , $ a_{\mathrm{d}}^{ * } $ , $ a_{\mathrm{p}}^{ * } $ and $ b_{\mathrm{b}}^{ * } $ of the remaining samples (46 in 2010 and 36 in 2011) were visualized and analyzed, and their relations to C _CHL, C _SPIM or C _SPM were studied, respectively. The main results are summarized as follows: (1) the $ {a_{{\mathrm{ph}}}}^{ * } $ values at 440 nm were 0.0367–0.7203 m²?mg^?1 with a mean of 0.1623?±?0.1426 m²?mg^?1 in 2010 and 0.0319–0.7735 m²?mg^?1 with a mean of 0.3145?±?0.1961 m²?mg^?1 in 2011; there existed significant, negative, and moderate correlations between $ {a_{{\mathrm{ph}}}}^{ * } $ and C _CHL at 400–700 nm in 2010 and 2011 (p?<?0.05); (2) The $ a_{\mathrm{d}}^{ * } $ values at 440 nm were 0.0672–0.2043 m²?g^?1 with a mean of 0.1022?±?0.0326 m²?g^?1 in 2010 and 0.0559–0.1347 m²?g^?1 with a mean of 0.0953?±?0.0196 m²?g^?1 in 2011; there existed negative correlations between $ a_{\mathrm{d}}^{ * } $ and C _SPIM, while the correlations showed overall decreasing and increasing trends before and after around 575 nm with increasing wavelengths, respectively; (3) The $ a_{\mathrm{p}}^{ * } $ values at 440 nm were 0.0690–0.1929 m²?g^?1 with a mean of 0.1036?±?0.0298 m²?g^?1 in 2010 and 0.0571–0.1321 m²?g^?1 with a mean of 0.1014?±?0.0191 m²?g^?1 in 2011, and the negative correlations between $ a_{\mathrm{p}}^{ * } $ and C _SPM were found in both years; (4) The $ b_{\mathrm{b}}^{ * } $ at the six wavelengths generally decreased with increasing wavelengths, while the $ b_{\mathrm{b}}^{ * } $ values at 420 nm were lower than those at 442 nm for some samples; the correlation between $ b_{\mathrm{b}}^{ * } $ and C _SPM increased with increasing wavelength. Such results can only represent the SIOPs during the sampling time periods, and more measurements and analyses considering different seasons need to be carried out in the future to comprehensively understand the SIOPs of Poyang Lake.     

西宁市非采暖季和采暖季PM2.5中14种金属元素特征

于2012年11月采暖季和2013年9月非采暖季,在青藏高原典型城市西宁市4个采样点采集细颗粒物(PM_(2.5))样品,共获得40个有效样品。用微波消解-ICP-MS法、原子荧光法分析了样品中14种重点防控金属。结果表明:14种重点防控金属中Ag、Tl平均质量浓度为0.10~0.50 ng/m~3,Co、Sb、Hg平均质量浓度为0.50~4.00 ng/m~3,V、Cd、Cr、Ni、Cu、As平均质量浓度为4.00~50.0 ng/m~3,Mn、Pb、Zn平均质量浓度为50.0~2 000 ng/m~3。采样期间,采暖季相比非采暖季,PM_(2.5)质量浓度有下降趋势,不同采样区金属元素浓度有增有减。富集因子分析结果表明,重点防控金属元素在非采暖季主要来源于土壤风沙扬尘、机动车尾气和工业排放,采暖季主要来源于土壤风沙扬尘、燃煤、燃油、机动车尾气和工业排放。非采暖季Zn、Ag、Cd、Hg、Tl和Pb富集因子较高,采暖季Zn、As、Ag、Cd、Sb、Hg、Tl、Pb富集因子较高,更容易受到人为源的影响。     

Airborne Dust Particle Counting Techniques

The paper briefly describes an electro-optical system for counting of dust particles, which is based on the scattering phenomena.Utilizing the scattering of light by various size particles present in the environment, various particle counting techniques have been developed in order to measure the scattered intensity of light. Light scatters in all directions but much more in the so-called near forward direction 17^∘ off axis, at 163^∘ from the light source in the visible range.On the basis of two techniques, the right angle and forward angle scattering, opto-mechanical systems have been developed which measure scattered intensity and particulate matter. The forward scattering Nephelometer is more sensitive and therefore is more suitable for pollution monitoring than the right angle scattering Nephelometer. Whereas the right angle scattering Nephelometer has the utility in extremely low concentration in ppb level owing to the excellent light trap efficiency in comparison to forward scattering Nephelometer. In this paper measurement techniques and measurement results associated with design and development of a real time particle analyser are also discussed.     

不同气团来源对广州细颗粒物理化特性的影响

利用2006年7月广州细颗粒物质量浓度、数谱分布与化学组成的观测数据与气团后向轨迹聚类分析结果,系统分析了不同气团来源对广州细颗粒物理化特性的影响。观测期间,广州气团来源可分成来自远海、近海、西面陆地和北面陆地4种类型。细颗粒物总数浓度水平在4种类型中基本相当。当气团来自远海时,二次转化影响较小,PM2.5质量浓度较低,颗粒物数浓度从大到小依次为老化爱根核模态新鲜爱根核模态度积聚模态;受到海洋气团的影响,Cl-在PM2.5中比例为4种类型中最大。气团来自近海时,颗粒物二次生成与老化现象突出,数谱峰值出现在积聚模态,而其他类型出现在爱根核模态;SO2-4、OC与NO-3之和在PM2.5中的比例大于50%,为4种类型中最高。气团来自西面陆地和北面陆地时,细颗粒物受陆地传输老化气团和本地来源影响均较明显。来自北面陆地时,250 nm以上颗粒物数浓度明显升高,是PM2.5平均浓度远高于其他类型的直接原因之一。     

超声提取-气相色谱质谱法测定大气PM2.5中正构烷烃

建立了超声提取-气相色谱质谱法测定大气PM2.5中32种正构烷烃方法,经离子温度优化、前处理比较、空白滤膜考察等获得了最佳的实验条件。研究发现,高、中、低3种浓度标准曲线的相关系数均在0.995以上,3种浓度的空白样品加标回收率分别为72.2%~117.8%、73.5%~104.4%、73.8%~109.5%,精密度均小于10%,实际样品加标回收率为75.7%~108.9%。当采样体积为24 m3时,各目标化合物的方法检出限为0.046~2.6 ng/m~3;经正构烷烃浓度范围为0.17~64.3 ng/m~3的1月及浓度范围为0.53~7.67 ng/m~3的6月的实际样品验证,该方法的检出限和测量范围也可较好的满足实际样品的测定。     

Formation and Emission of N2O and CH4 from Compost Heaps of Organic Household Waster

Composting can be a source of N₂O andCH₄ production. In this investigation, differentcompost heaps of organic household waste weremonitored with the focus on potential formation ofCH₄ and N₂O in the heaps and emission ofthese gases from the heaps. The studied compost heapshad different compost ages, turning intervals andcompost sizes. The analysed compost gases containedbetween 1–3421 L of N₂O-N L^-1 and 0–470 mL of CH₄ L^-1. The emission rates ofN₂O and CH₄ from the compost heaps werebetween 1–1464 mg N₂O m^-2 day^-1 and0–119 000 mg CH₄ m^-2 day^-1. These verylarge differences in compost gas composition andemission indicate the importance of compostmanagement. The results also give an understanding ofwhere in the composting process an increasing emissionof N₂O and CH₄ can occur.