Local and regional air pollution in Ireland during an intensive aerosol measurement campaign

An intensive two month measurement campaign has been performed during a two year study of major component composition of urban PM10 and PM2.5 in Ireland (J. Yin, A. G. Allen, R. M. Harrison, S. G. Jennings, E. Wright, M. Fitzpatrick, T. Healy, E. Barry, D. Ceburnis and D. McCusker, Atmos. Res., 2005, 78(3-4), 149-165). Measurements included size-segregated mass, soluble ions, elemental carbon (EC) distributions, fine and coarse fraction organic carbon (OC) and major gases along with standard meteorological measurements. The study revealed that urban emissions in Ireland had mainly a local character and therefore were confined within a limited area of 20-30 km radius, without significantly affecting regional air quality. Gaseous measurements have shown that urban emissions in Ireland had clear, but fairly limited influence on the regional air quality due to favorable mixing conditions at higher wind speeds, in particular from the western sector. Size-segregated mass and chemical measurements revealed a clear demarcation size between accumulation and coarse modes at about 0.8 microm which was constant at all sites. Carbonaceous compounds at the urban site accounted for up to 90% of the particle mass in a size range of 0.066-0.61 microm. Nss SO4(2-) concentrations in PM2.5 were only slightly higher at the urban site compared to the rural or coastal sites, while NO3- and NH4+ concentrations were similar at the urban and coastal sites, but were a factor of 2 to 3 higher than at the rural site. OC was highly variable between the sites and revealed clear seasonal differences. Natural or biogenic OC component accounted for <10% in winter and up to 30% in summer of the PM2.5 OC at urban sites. A contribution of biogenic OC component to PM2.5 OC mass at rural site was dominant.     

Chemical compositions and sources of atmospheric PM10 in heating, non-heating and sand periods at a coal-based city in northeastern China

Mass concentrations and chemical components (18 elements, 9 ions, organic carbon [OC] and elemental carbon [EC]) in atmospheric PM(10) were measured at five sites in Fushun during heating, non-heating and sand periods in 2006-2007. PM(10) mass concentrations varied from 62.0 to 226.3 μg m(-3), with 21% of the total samples' mass concentrations exceeding the Chinese national secondary standard value of 150 μg m(-3), mainly concentrated in heating and sand periods. Crustal elements, trace elements, water-soluble ions, OC and EC represented 20-47%, 2-9%, 13-34%, 15-34% and 13-25% of the particulate matter mass concentrations, respectively. OC and crustal elements exhibited the highest mass percentages, at 27-34% and 30-47% during heating and sand period. Local agricultural residuals burning may contribute to EC and ion concentrations, as shown by ion temporal variation and OC and EC correlation analysis. Heavy metals (Cr, Ni, Zn, Cu and Mn) from coal combustion and industrial processes should be paid attention to in heating and sand periods. The anion/cation ratios exhibited their highest values for the background site with the influence of stationary sources on its upper wind direction during the sand period. Secondary organic carbon were 1.6-21.7, 1.5-23.0, 0.4-17.0, 0.2-33.0 and 0.2-21.1 μg m(-3), accounting for 20-77%, 44-88%, 4-77%, 8-69% and 4-73% of OC for the five sampling sites ZQ, DZ, XH, WH and SK, respectively. From the temporal and spatial variation analysis of major species, coal combustion, agricultural residual burning and industrial emission including dust re-suspended from raw material storage piles were important sources for atmospheric PM(10) in Fushun at heating, non-heating and sand periods, respectively. It was confirmed by principal component analysis that coal combustion, vehicle emission, industrial activities, soil dust, cement and construction dust and biomass burning were the main sources for PM(10) in this coal-based city.     

Characteristics of Carbonaceous Aerosol at Taichung Harbor, Taiwan during Summer and Autumn Period of 2005

In recent years, suspended particle pollution has become a serious problem in Taiwan. The carbonaceous materials EC and OC are play important roles in various atmospheric processes. The primary OC/EC ratio approach is applied to assess the contribution of secondary organic aerosol (SOA) to the PM_2.5 and PM₁₀ mass at the Taichung harbor sampling site. The results indicated that the average EC and OC concentration were 1.06 and 6.50 μg m⁻³, respectively, in fine particulate. And the average EC and OC concentration were 4.04 and 40.32 μg m⁻³, respectively, in coarse particulate at Taichung Harbor sampling site. In addition, and the average EC/OC rations was 8.72 in fine particle, respectively, at Taichung Harbor, Taiwan during summer and autumn period of 2005. The fine particle exhibited high particulate concentrations in October, and lower concentration particulate occurred in August. And in this study OC and EC concentrations in this study are compared with those in other cities. The results of EC and OC concentration in this study are also compare with those other cities.     

Particle-bound polycyclic aromatic hydrocarbons in an urban, industrial and rural area in the western Mediterranean

Particle-bound PAHs were measured at three sites in southeastern Spain (an urban background location, a suburban-industrial site in the vicinity of two cement plants and a rural area) in order to investigate the influence of the type of location on PAH concentrations. A clear influence of cement production on particulate PAH levels could not be established since for the urban background and suburban-industrial sites the average concentrations of total PAHs in the PM2.5 fraction were very similar (1.085 and 1.151 ng m(-3), respectively), with benzo[b+k]fluoranthene and chrysene as the predominant compounds. Diagnostic ratios, used to identify PAH emission sources, pointed to traffic as the main source of particulate PAH at both locations. As expected, PAH levels at the rural site were significantly lower (0.408 ng m(-3) in the PM10 fraction) due to increasing distance from the emission sources. PAH seasonal variations at the urban background and suburban-industrial sites were the same as reported in many previous studies. Average winter to summer ratios for total PAHs were 4.4 and 4.9 for the urban background and industrial sites, in that order. This seasonal cycle could be partially explained by the higher temperature and solar radiation during summer enhancing PAH evaporation from the particulate phase and PAH photochemical degradation, respectively. The study of PAH distribution between the fine and coarse fraction at the urban site revealed that on average around 80% of total PAHs were associated with fine particles.     

宁波PM10中有机碳和元素碳的季节变化及来源分析

为了探讨宁波市大气颗粒物中浓度水平与季节变化,2010年1、5、8、11月分季节采集了宁波市大气中PM10样品,在宁波连续观测了PM10以及有机碳(OC)、元素碳(EC)的浓度变化,并探讨宁波全年各季碳气溶胶污染变化特征;PM10中OC和EC相关性较好,说明OC与EC的来源相同,各采样点PM10中OC/EC的各季均值大部分超过2.0,表明宁波空气中存在一定的二次污染。宁波秋季SOC占OC含量高于其他季节。从PM10中8个碳组分丰度初步判断宁波市颗粒物中碳的主要来源是汽车尾气、道路扬尘及燃煤。     

Chemical composition of ambient particulate matter and redox activity

Exposure to ambient particulate matter (PM) has been associated with a number of adverse health effects. Increasing studies have suggested that such adverse health effects may derive from oxidative stress, initiated by the formation of reactive oxygen species (ROS) within affected cells. The study aimed to assess physical characteristics and chemical compositions of PM and to correlate the results to their redox activity. PM_2.5 (mass aerodynamic diameter ≤2.5 μm) and ultrafine particles (UFPs, mass media aerodynamic diameter <0.1 μm) were collected in an urban area, which had heavy traffic and represented ambient air pollution associated with vehicle exhaust. Background samples were collected in a rural area, with low traffic flow. Organic carbon (OC), elemental carbon (EC), polycyclic aromatic hydrocarbons (PAHs), and metals were analyzed. The dithiothreitol activity assay was used to measure the redox activity of PM. Results showed that UFPs have higher concentrations of OC, EC, and PAHs than those of PM_2.5. Several metals, including Fe, Cu, Zn, Ti, Pb, and Mn, were detected. Among them, Cu had the highest concentrations, followed by Fe and Zn. Organic carbon constituted 22.8% to 59.7% of the content on the surface of PM_2.5 and UFPs. Our results showed higher redox activity on a per PM mass basis for UFPs as compared to PM_2.5. Linear multivariable regression analyses showed that redox activity highly correlated with PAH concentrations and organic compounds, and insignificantly correlated with EC and metals, except soluble Fe, which increased redox activity in particle suspension due to the presence of ROS.     

Estimation of the contributions of long range transported aerosol in East Asia to carbonaceous aerosol and PM concentrations in Seoul, Korea using highly time resolved measurements: a PSCF model approach

The contributions of long range transported aerosol in East Asia to carbonaceous aerosol and particulate matter (PM) concentrations in Seoul, Korea were estimated with potential source contribution function (PSCF) calculations. Carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)), PM(2.5), and PM(10) concentrations were measured from April 2007 to March 2008 in Seoul, Korea. The PSCF and concentration weighted trajectory (CWT) receptor models were used to identify the spatial source distributions of OC, EC, PM(2.5), and coarse particles. Heavily industrialized areas in Northeast China such as Harbin and Changchun and East China including the Pearl River Delta region, the Yangtze River Delta region, and the Beijing-Tianjin region were identified as high OC, EC and PM(2.5) source areas. The conditional PSCF analysis was introduced so as to distinguish the influence of aerosol transported from heavily polluted source areas on a receptor site from that transported from relatively clean areas. The source contributions estimated using the conditional PSCF analysis account for not only the aerosol concentrations of long range transported aerosols but also the number of transport days effective on the measurement site. Based on the proposed algorithm, the condition of airmass pathways was classified into two types: one condition where airmass passed over the source region (PS) and another condition where airmass did not pass over the source region (NPS). For most of the seasons during the measurement period, 249.5-366.2% higher OC, EC, PM(2.5), and coarse particle concentrations were observed at the measurement site under PS conditions than under NPS conditions. Seasonal variations in the concentrations of OC, EC, PM(2.5), and coarse particles under PS, NPS, and background aerosol conditions were quantified. The contributions of long range transported aerosols on the OC, EC, PM(2.5), and coarse particle concentrations during several Asian dust events were also estimated. We also investigated the performance of the PSCF results obtained from combining highly time resolved measurement data and backward trajectory calculations via comparison with those from data in low resolutions. Reduced tailing effects and the larger coverage over the area of interest were observed in the PSCF results obtained from using the highly time resolved data and trajectories.     

Results of An Indoor Size Fractionated PM School Sampling Program in Libby, Montana

Libby, Montana is the only PM_2.5 nonattainment area in the western United States with the exceptions of parts of southern California. During January through March 2005, a particulate matter (PM) sampling program was conducted within Libby’s elementary and middle schools to establish baseline indoor PM concentrations before a wood stove change-out program is implemented over the next several years. As part of this program, indoor concentrations of PM mass, organic carbon (OC), and elemental carbon (EC) in five different size fractions (>2.5, 1.0–2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) were measured. Total measured PM mass concentrations were much higher inside the elementary school, with particle size fraction (>2.5, 0.5–1.0, 0.25–0.5, and <0.25 μm) concentrations between 2 and 5 times higher when compared to the middle school. The 1.0–2.5 μm fraction had the largest difference between the two sites, with elementary school concentrations nearly 10 times higher than the middle school values. The carbon component for the schools’ indoor PM was found to be predominantly composed of OC. Measured total OC and EC concentrations, as well as concentrations within individual size fractions, were an average of two to five times higher at the elementary school when compared to the middle school. For the ultrafine fraction (<0.25), EC concentrations were similar between each of the schools. Despite the differences in concentrations between the schools at the various fraction levels, the OC/EC ratio was determined to be similar.     

Chemical Composition and Sources of PM10 and PM2.5 Aerosols in Guangzhou, China

Aerosol samples of PM10 and PM2.5 are collected in summertime at four monitoring sites in Guangzhou, China. The concentrations of organic and elemental carbons (OC/EC), inorganic ions, and elements in PM10 and PM2.5 are also quantified. Our study aims to: (1) characterize the particulate concentrations and associated chemical species in urban atmosphere (2) identify the potential sources and estimate their apportionment. The results show that average concentration of PM2.5 (97.54 μg m⁻³) in Guangzhou significantly exceeds the National Ambient Air Quality Standard (NAAQS) 24-h average of 65 μg m⁻³. OC, EC, Sulfate, ammonium, K, V, Ni, Cu, Zn, Pb, As, Cd and Se are mainly in PM2.5 fraction of particles, while chloride, nitrate, Na, Mg, Al, Fe, Ca, Ti and Mn are mainly in PM2.5-10 fraction. The major components such as sulfate, OC and EC account for about 70–90% of the particulate mass. Enrichment factors (EF) for elements are calculated to indicate that elements of anthropogenic origins (Zn, Pb, As, Se, V, Ni, Cu and Cd) are highly enriched with respect to crustal composition (Al, Fe, Ca, Ti and Mn). Ambient and source data are used in the multi-variable linearly regression analysis for source identification and apportionment, indicating that major sources and their apportionments of ambient particulate aerosols in Guangzhou are vehicle exhaust by 38.4% and coal combustion by 26.0%, respetively.     

Seasonal Variations of PM10 and TSP in Residential and Industrial Sites in an Urban Area of Kolkata, India

The objective of the study is to investigate seasonal and spatial variations of PM₁₀ (particulate matter with aerodynamic diameter less than or equal to 10 μm) and TSP (total suspended particulate matter) of an Indian Metropolis with high pollution and population density from November 2003 to November 2004. Ambient concentration measurements of PM₁₀ and TSP were carried out at two monitoring sites of an urban region of Kolkata. Monitoring sites have been selected based on the dominant activities of the area. Meteorological parameters such as wind speed, wind direction, rainfall, temperature and relative humidity were also collected simultaneously during the sampling period from Indian Meteorological Department, Kolkata. The 24 h average concentrations of PM₁₀ and TSP were found in the range 68.2–280.6 μg/m³ and 139.3–580.3 μg/m³ for residential (Kasba) area, while 62.4–401.2 μg/m³ and 125.7–732.1 μg/m³ for industrial (Cossipore) area, respectively. Winter concentrations of particulate pollutants were higher than other seasons, irrespective of the monitoring sites. It indicates a longer residence time of particulates in the atmosphere during winter due to low winds and low mixing height. Spread of air pollution sources and non-uniform mixing conditions in an urban area often result in spatial variation of pollutant concentrations. The higher particulate pollution at industrial area may be attributed due to resuspension of road dust, soil dust, automobile traffic and nearby industrial emissions. Particle size analysis result shows that PM₁₀ is about 52% of TSP at residential area and 54% at industrial area.     

Overview of particulate exposures in the US trucking industry

As part of a large epidemiologic study of lung cancer, 55,000 subjects, we have conducted a nation-wide survey of particulate exposures in the US trucking industry. The goal is to differentiate the risks from various types of particulate exposures, such as traffic emissions and general air pollution. We hypothesize that exposures defined by job and work site characteristics can be linked with subjects using their personal job histories. This report covers exposures at 36 randomly chosen large truck freight terminals in the US. Measurements were made of PM2.5, elemental carbon (EC), and organic carbon (OC) upwind of the terminal (background) and in work areas, and by personal samples. Significant differences in exposure intensity, microg m(-3), were found for work locations and jobs relative to background levels (GM[GSD]) at terminal sites: PM2.5 9.8[2.34], EC 0.5[3.24], and OC 5.0[1.76]. Using EC as a marker for diesel particles, work locations varied significantly: office 0.3[3.7], dock area 0.7[2.89] and shop area 1.5[3.52]), as did job titles (non-smokers): clerk 0.1[9.98], dock worker 0.8[2.13], and mechanic 2.0[3.82]. Cigarette smoking contributed substantially to personal exposures, approximately doubling PM2.5 and OC, but having less of an effect on EC. Large differences were seen across the terminal sites due to differences in local regional air pollution levels from traffic and other sources. We conclude that it will be possible to estimate current exposures of the cohort using an exposure assignment matrix based on job title, work location, and terminal site. This distribution overlaps substantially with the general public's exposure to these sources.     

Assessment of diesel particulate matter exposure in the workplace: freight terminals

A large study has been undertaken to assess the exposure to diesel exhaust within diesel trucking terminals. A critical component of this assessment is an analysis of the variation in carbonaceous particulate matter (PM) across trucking terminal locations; consistency in the primary sources can be effectively tracked by analyzing trends in elemental carbon (EC) and organic molecular marker concentrations. Ambient samples were collected at yard, dock and repair shop work stations in 7 terminals in the USA and 1 in Mexico. Concentrations of EC ranged from 0.2 to 12 microg m(-3) among the terminals, which corresponds to the range seen in the concentration of summed hopanes (0.5 to 20.5 ng m(-3)). However, when chemical mass balance (CMB) source apportionment results were presented as percent contribution to organic carbon (OC) concentrations, the contribution of mobile sources to OC are similar among the terminals in different cities. The average mobile source percent contribution to OC was 75.3 +/- 17.1% for truck repair shops, 65.4 +/- 20.4% for the docks and 38.4 +/- 9.5% for the terminal yard samples. A relatively consistent mobile source impact was present at all the terminals only when considering percentage of total OC concentrations, not in terms of absolute concentrations.     

Analysis of acidic components, heavy metals and PAHS of particulate in the Changwon–Masan area of Korea

This study is an analysis of the concentrations and components of heavy metals in PM_2.5 and the total suspended particulate (TSP) collected at a mechanical industrial complex (IC) site in Changwon and at a residential site in Masan, Korea. Particulate was collected during two sampling periods, from the late summer to the early fall and from the middle to late fall, at the IC site and one sampling period, from the middle fall to the early winter, at the residential site. PM_2.5 and TSP samples were taken by an annular denuder system and a hi-volume air sampler, respectively. The authors also identified the concentrations and components of heavy metals extracted from the PM_2.5 and TSP filters, the acidic components extracted from the PM_2.5 filters, and the polycyclic aromatic hydrocarbons (PAHs) extracted from polyurethane foam (PUF) plug. The average concentrations of the PM_2.5 collected at the IC and residential sites were very similar. Major sources of PM_2.5 at the study sites, however, were air emissions from vehicles and industry as well as emissions from residential heating and soil origins, respectively. The higher concentrations of the TSP at the IC site, as compared to those at the residential site, were due to either increased suspended dust from vehicle emissions or re-suspended road dust because of increased vehicle speeds near the IC site. Heavy metal concentrations in the TSPs were higher than those in the PM_2.5. The heavy metal concentrations in the PM_2.5 and TSP at the IC site with heavy traffic were substantially greater than those at the residential site. The concentrations of TSP and heavy metals and PAHs in PM during the period of the middle to late fall was much higher than those during the period of the late summer to early fall at the IC site. This is because of the difference in meteorological characteristics and energy uses between two periods. The residential site also showed higher concentrations of acidic anions while the IC site showed higher concentrations of acidic cation. Secondary aerosols or particulates, such as ammonium nitrate or ammonium nitrite, might have been important constituents of the PM_2.5 at the residential site. The PAHs in the TSP collected at the IC site was greatly affected by traffic and industry emissions consisting mostly of high molecular weight PAHs with two to four rings. PAHs in the TSP at the site, however, were affected by residential heating and air emissions from small chemical plants having higher concentrations of low molecular weight PAHs with five to six rings.     

Sampling techniques for the assessment of anthropogenic vapour and particulate mercury in the Brazilian Amazon atmosphere

A system, based on annular gold-coated denuders, was optimized and used in the atmospheric sampling of mercury in urban and rural sites of the Alta Floresta, a region in the Brazilian Amazon. Results showed that vapour phase mercury (Hgv) is dominant in samples collected in both sites. However, particulate mercury (Hg) may sometimes be significant at the urban site, with values representing up to 77% of the total Hg collected during sampling, but may also be insignificant at the same site, depending on the gold commercialization activity and, probably, on the meteorological conditions during the sampling period. The presence of mercury in both the vapour and particulate phases in the atmosphere of the urban site can explain the high mercury concentrations found in urban dust reported for some cities in the Amazon, and also the relatively high Hg concentrations found in soils adjacent to the urban centre of Alta Floresta. It appears that the urban dust of "garimpo" areas in the Amazon can act as an efficient adsorber of Hgv emitted by gold dealer operations during the purification process. Mercury emissions from gold dealer shops in the Amazon have been considered as a human health risk through the inhalation of Hg vapour. However, although true for indoor sites, the significant contribution of particulate phase Hg shown in this study in outdoor urban sites calls for a re-evaluation of the risk assessment estimates performed up to now in urban centres in the Amazon.     

Aerosol chemical characteristics of an island site in the Bay of Bengal (Bhola-Bangladesh)

Aerosol constituents (elemental carbon, organic carbon, soluble ions including organic acids, and selected trace metals) were investigated from samples of a field campaign taking place at Bhola Island in the Bay of Bengal (Bangladesh). The campaign took place in the pre-monsoon season (May 2001) using low volume samplers. Carbonaceous material comprised the majority of the analysed components. The average concentrations of EC and OC were 2.8 and 4.6 microg m(-3), respectively. Oxalic acid was the most abundant dicarboxylic acid (average 268 ng m(-3)) followed by malonic and malic acid. The contribution of carboxylic acids-carbon to organic carbon was 2.0%. Average concentrations observed for sulfate and nitrate were 3.7 microg m(-3) and 1.5 microg m(-3). Two different types of aerosol were identified at the rural background site on Bhola Island during southerly synoptic flow by means of trajectory analysis: air masses were transported from the Bay of Bengal to the sampling site in all cases. However, during "Period 1" they experienced longer residence times over the Indian Ocean, while the "Period 2" trajectories came along the Indian coast or passed over the Indian continent. During Period 1 the concentration levels of soluble ions were a factor of 4-6 lower than during Period 2. The concentrations of EC, OC and K differed less than a factor of 1.5 between the two periods. The Period 1 aerosol showed similarities to the haze layers observed during winter-monsoon conditions south of India during the INDOEX experiment. Based on EC/TC and K/EC ratios we find that around 80% of the carbonaceous aerosol from Period 1 in Bhola is from fossil fuel and only around 50% from Period 2. Absolute concentrations of carbonaceous species, soluble ions and trace metals indicate that the background site on Bhola Island is affected by emissions from urbanized regions of Southeast Asia.     

TSP, PM depositions, and trace elements in the vicinity of a cement plant and their source apportionments using chemical mass balance model in Izmir, Turkey

Total suspended particles mass concentrations (TSP) and bulk depositions of particulate matter (PM depositions) were measured around a cement plant located in the multi-impacted area to assess the affect of the plant on the ambient air in the vicinity in Izmir, Turkey. TSP samples were collected five times a month whereas PM depositions were sampled monthly at four sites between August 2003 and January 2004. The concentrations of Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V, and Zn in TSP and PM depositions (except Cu) were reported. Chemical mass balance (CMB) receptor model with local source profiles was run in order to calculate the source contributions of the PM sources to the concentrations of TSP, PM depositions, and trace elements. Traffic was found to be the major contributor to TSP whereas PM depositions dominantly result from area sources including several stone quarries, concrete plants, lime kilns, and asphalt plants in the region. CMB model results indicate that the cement plant is a significant contributor to TSP, PM depositions, and trace elements, particularly Cd.     

Summer time haze characteristics of the urban atmosphere of Gwangju and the rural atmosphere of Anmyon, Korea

An extensive visibility monitoring was carried out simultaneously in the urban area of Gwangju and the rural area of Anmyon, Korea. This study examines patterns of visibility impairment and haze-forming pollutant concentrations on both sites resulting from natural and anthropogenic sources of gases and particles. Optical visibility measurements by a transmissometer, a nephelometer and an aethalometer provide aerosol light extinction, scattering, and absorption coefficients for both sites. In order to investigate the physico-chemical characteristics of atmospheric aerosols, aerosol samples were collected by various aerosol samplers at GJVMS (Gwangju Visibility Monitoring Station) and at KGAWO (Korea Global Atmosphere Watch Observatory), respectively. In addition, haze characteristics causing visibility impairment at those two sites were analyzed to obtain source contributions by regionally transported aerosols using grid analysis and display system (GrADS) from NECP reanalysis data. During the intensive monitoring period, ammonium sulfate was dominantly responsible for the fine particle mass loading at GJVMS, whereas organic carbon was the largest contributor at KGAWO. Light scattering by particles accounted for 52.8 to 81.3% of the range at the urban site, GJVMS and for 72.1 to 94.2% of the range at the rural site, KGAWO. Light absorption by the EC and NO₂ was between 14.5 and 34.8% at GJVMS, which was higher than the observed 1.1 ∼ 6.8% at KGAWO, respectively. Light scattering by aerosol was higher in the rural area than in the urban area. And organic carbon concentration was observed to be significantly higher than the concentration of elemental carbon at KGAWO. These haze-forming carbonaceous particles originate from anthropogenic pollutants at the urban atmosphere but they can be produced by natural environments such as marine and forest at the rural atmosphere.     

Characterization of Volatile Organic Compounds (VOCs) and Their Sources in the Air of Izmir, Turkey

Air samples were collected in Izmir, Turkey at two (suburban and urban) sites during three sampling programs in 2002 and 2004 to determine the ambient concentrations of several monoaromatic, chlorinated and oxygenated volatile organic compounds (VOCs). Samples were analyzed for 60 VOCs using gas chromatography/mass spectrometry and 28 compounds were detected in most samples. On the average, urban air VOC concentrations were about four times higher than those measured at the suburban site. Toluene (40.6%) was the most abundant compound in suburban site and was followed by benzene (7.4%), o,m-xylene (6.5%), and 1,2-dichloroethane (5.1%). In urban site, toluene (30.5%), p-xylene (14.9%), o,m-xylene (11.4%), and ethyl benzene (7.2%) were the dominating compounds in summer. In winter, toluene (31.1%), benzene (23.9%), 1,2-dichloroethane (9.5%), and o,m-xylene (8.2%) were the most abundant compounds. Receptor modeling (positive matrix factorization) has been performed to estimate the contribution of specific source types to ambient concentrations. Six source factors (gasoline vehicle exhaust, diesel vehicle exhaust+residential heating, paint production/application, degreasing, dry cleaning, and an undefined source) were extracted from the samples collected in the urban site. Three source factors (gasoline vehicle exhaust, diesel vehicle exhaust, and paint production/application) were identified for the suburban site.     

2014-2018年南京PM2.5中碳组分污染特征分析

利用在线高分辨率仪器对2014-2018年南京市PM2.5中有机碳(OC)、元素碳(EC)进行了连续监测,结果表明:离线分析法与在线分析法对OC、EC的测定结果具有很好的线性相关性,离线分析的EC、OC浓度高于在线自动监测值;2014-2018年南京OC与EC的平均质量浓度分别为(6. 38±3. 91)μg/m^3和(3. 12±1. 76)μg/m^3,整体呈下降趋势,冬季OC与EC均较高,夏季两者质量浓度较低。OC和EC均呈现夜间高、白天低的日变化规律,OC与EC第一个峰值均出现在08:00左右,OC第二个峰值出现在20:00前后;夏季OC与EC相关性最低,冬季最高,NO2、CO与OC、EC的相关性总体高于SO2,表明燃料燃烧对碳气溶胶有一定贡献,但没有交通源的贡献显著,夏季O3与OC呈现一定程度的正相关性。利用最小相关系数法(MRS)计算大气OC中一次有机碳(POC)和二次有机碳(SOC),结果显示OC中以POC为主,但SOC呈逐年上升趋势,2018年SOC质量浓度达1. 96μg/m3,在OC中占比达31. 9%,后续颗粒物污染治理的重点可能应关注VOCs。     

External Contribution to Urban Air Pollution

Elevated particulate matter concentrations in urbanlocations have normally been associated with local trafficemissions. Recently it has been suggested that suchepisodes are influenced to a high degree by PM₁₀sources external to urban areas. To further corroboratethis hypothesis, linear regression was sought betweenPM₁₀ concentrations measured at eight urban sites inthe U.K., with particulate sulphate concentration measuredat two rural sites, for the years 1993–1997. Analysis ofthe slopes, intercepts and correlation coefficientsindicate a possible relationship between urban PM₁₀and rural sulphate concentrations. The influences of winddirection and of the distance of the urban from the ruralsites on the values of the three statistical parametersare also explored. The value of linear regression as ananalysis tool in such cases is discussed and it is shownthat an analysis of the sign of the rate of change of theurban PM₁₀ and rural sulphate concentrations providesa more realistic method of correlation. The resultsindicate a major influence on urban PM₁₀ concentrations from the eastern side of the UnitedKingdom. Linear correlation was also sought using PM₁₀ data from nine urban sites in London and nearby ruralRochester. Analysis of the magnitude of the gradients andintercepts together with episode correlation analysisbetween the two sites showed the effect of transportedPM₁₀ on the local London concentrations. This articlealso presents methods to estimate the influence of ruraland urban PM₁₀ sources on urban PM₁₀ concentrations and to obtain a rough estimate of thetransboundary contribution to urban air pollution from thePM₁₀ concentration data of the urban site.