Measured components in total suspended particulate matter in a Kenyan urban area

Nairobi city has a population of over 1.5 million and is growing at a rate of about 70 persons per day. Various activities in the city such as construction work, industrial processes, use of unroadworthy cars, and dust blown off unpaved roads contribute enormously to suspended particulate matter in the air. In this paper, analysis by gravimetric and energy dispersive X-ray fluorescence (EDXRF) of the suspended particulate matter in the air in the city centre, an industrial area and one residential area was carried out. The total suspended particulate matter (TSP) mean levels ranged from 69.983 to 397.903 μg m⁻³. The following components were measured from the TSP, mean values in μg m⁻³: iron 6.014–7.547, potassium 1.252–6.432, titanium 0.286–1.698, manganese 0.158–1.683, lead 0.395–1.321, bromine 0.122–0.707, zinc 0.159–0.678 and zirconium 0.017–0.245. The values of lead obtained (0.395–1.321 μg m⁻³) fall within the WHO recommendations, but compared to the values reported in some European countries, they are high. Most of the elements had low enrichment factors except for lead (104–353), bromine (429–1533) and zinc (14–79). Bromine and lead were highly correlated to the number of light vehicles (p=0.874 and 0.942, respectively). In addition the ratio of Br:Pb by weight was in the range 0.309–0.535, while the correlation factor for Br:Pb was 0.951, leading to the conclusion that both elements came from leaded gasoline.     

Dispersion of sulphur dioxide around the thermal power plant at Ahmedabad,India

Air quality due to the release of sulphur dioxide from the thermal power plant within the city limits of Ahmedabad has been computed employing a point, area and line dispersion model. To estimate probable air quality, the meteorological data for 3 consecutive days in the middle of each month of 1983 is used. The concentration of sulphur dioxide is computed at a distance of every 500 m in 16 directions up to the city limit. The air quality in the worst case is estimated in downwind distances under unfavourable meteorological conditions.The probable zones of high concentrations of sulphur dioxide over residential, commercial and industrial areas of the city are below the ambient air quality standards set by the U.S. EPA in 1971 almost throughout the year. However, in the months of April and October the zone of high concentration (500 μg m⁻³) exceeds the EPA standard. Also, under the most unfavourable meteorological conditions, the estimated high ground-level concentration of sulphur dioxide can reach up to 1000 μg m⁻³ at a distance of 1.25 km from the thermal power plant. This may be attributed to the effect of fumigation.     

Quantitative analysis of airborne breathable particles: A comparison between different analytical techniques

Air samples, collected over 6 months, have been analysed by scanning electron microscopy (SEM) with the aim to characterize quantitatively the airborne particulate in an urban area. Total suspended particulate (TSP) and Pb concentrations (in μg m⁻³) were estimated by inserting into a simple model the particulate data obtained by SEM.Daily concentration trends were compared with trends measured by gravimetric (TSP) and atomic absorption spectroscopy (Pb) techniques. The correlation coefficients resulted to be 0.8 for TSP and 0.85 for Pb. These results indicate that SEM can be used to have a good evaluation on pollution by airborne breathable particles.     

Spatial and temporal patterns in nitrogen dioxide concentrations in a hot desert region

This paper reports seasonal and spatial variations in the ambient air concentration of nitrogen dioxide throughout the State of Bahrain, from February to December 1992. Monitoring sites were chosen to include urban areas with high traffic density, suburban areas with low traffic density, commercial and industrial areas. Correlations between meteorological parameters and mean NO₂ concentrations were analysed, and NO₂ levels were only significantly correlated with temperature (r = 0.63). Only February, a winter month, showed a significantly lower concentration of NO₂ with an overall mean value of 23 μgm⁻³, whereas in August, a summer month, it was 33 μgm⁻³. The results revealed that in a hot region like Bahrain, NO₂ concentrations do not show significant monthly variations. Also summer-averaged NO₂ values exceeded corresponding spring and winter values. In cold regions opposite patterns were observed. Moreover, the results revealed significant spatial variations in NO₂ concentrations. In suburban areas with low traffic density, the overall mean NO₂ level was 15, with a range of 12–17 μg m⁻³, while in urban areas with high traffic density, the overall mean value was 52 with a range of 44–60 μg m⁻³. The mean NO₂ value in industrial sites with low traffic density was 21 with a range of 14–27 μg m⁻³, whereas in the same areas near major roads, it was 32 with a range of 31–32 μg m⁻³. These results indicate that automobiles exhaust are the dominant source of NO₂ in Bahrain. The highest NO₂ levels were found in roads with high traffic density, which are narrow, with several traffic lights and roundabouts, suggesting the effect of road geometry on NO₂ levels.     

Urban air pollution in Brazil: Acetaldehyde and other carbonyls

We have measured ambient levels of carbonyls in three major urban areas of Brazil: Sao Paulo, Rio de Janeiro and Salvador. The most abundant carbonyls were acetaldehyde (up to 63 μg m⁻³, or 35 ppb) followed by formaldehyde (up to 42 μg m⁻³, or 34 ppb), and acetone (up to 20 ppb). Levels of 10 other aliphatic and aromatic carbonyls were in the range 0–5 ppb. Total carbonyl concentrations were in the range 11–75 ppb. Indoor levels were also measured at several locations in Salvador. High levels of acetaldehyde, 430 μg m⁻³ or 240 ppb, were measured in a highway tunnel.Using carbonyl/CO concentration ratios, mobile source emissions of carbonyls are estimated for the Sao Paulo area. Ambient levels of acetaldehyde and acetaldehyde/formaldehyde concentration ratios in Brazil are compared to those for other urban areas, and are briefly discussed in relation with the large scale use of ethanol as a vehicle fuel.     

Air pollutant concentrations in Varanasi,India

This study reports the diurnal patterns in the concentrations of ozone (O₃), nitrogen dioxide (NO₂), sulphur dioxide (SO₂) and total suspended particulate matter (TSP) in the urban atmosphere of Varanasi city in India during 1989. The city was divided into five zones and three monitoring stations were selected in each zone.Ambient concentrations of NO₂ and SO₂ were maximum during winter but ozone and TSP concentrations were highest during summer. The measured maximum concentrations (2-h average) were 150 and 231 μg m⁻³ (0.078 and 0.086 ppm) for NO₂ and SO₂, respectively, for the winter season. Ozone and TSP concentrations reached a maximum of 160 (0.08 ppm) and 733 μg m⁻³, respectively, in the summer. NO₂ and SO₂ concentrations peaked in the morning and evening. Peak concentrations of O₃ occurred in the afternoon, generally between noon and 4 p.m. Maximum concentrations of O₃, NO₂, SO₂ and TSP were measured in zones I and II, and minimum in zone V.     

Characteristics of atmospheric particles and heavy metals in winter in Chang-Zhu-Tan city clusters, China

To understand the pollution characteristics of atmospheric particles and heavy metals in winter in Chang-Zhu-Tan city clusters, China, total suspended particulate(TSP) and PM10samples were collected in cities of Changsha, Zhuzhou and Xiangtan from December 2011 to January 2012, and heavy metals of Cd, Pb, Cr, and As were analyzed. It shows that the average TSP concentration in Changsha, Zhuzhou and Xiangtan were(183 ± 73),(201 ± 84) and(190 ± 66) μg/m3respectively, and the average PM10 were(171 ± 82),(178 ± 65) and(179 ± 55) μg/m3respectively. The lowest TSP and PM10concentrations occurred at the background Shaping site of Changsha. The average ratio of ρ(PM10)/ρ(TSP) was 91.9%, ranging from 81.3% to 98.9%. Concerning heavy metals, in TSP samples, the concentration of Cr, As, Cd and Pb were 28.8–56.5, 18.1–76.3, 3.9–26.1 and 148.0–460.9 ng/m3, respectively, while in PM10samples, were 16.4–42.1, 15.5–67.9, 3.3–22.2 and 127.9–389.3 ng/m3, respectively. The enrichment factor of Cd was the highest, followed by Pb and As, while that of Cr was the lowest.     

Characterization and source identification of respirable particulate matter in Athens,Greece

Twenty-seven samples of respirable particulate matter (RP) were collected in central Athens during the summer of 1987. The samples were analyzed for the concentration SO₄²⁻ and NO₃⁻ (collected with Teflon and nylon filters and analyzed by ion-chromatography); organic and elemental carbon (collected on quartz fiber filters and analyzed with a thermo-optical method); and 20 elements (collected on Teflon filters and analyzed by proton-induced X-ray emission spectroscopy). Simultaneously collected samples for SO₂ and HNO₃ were also evaluated (collected with annular denuders and analyzed by ion-chromatography). T The average RP concentration measured was 80.7 μg m⁻³, well above the USEPA annual standard for PM₁₀ aerosol. In addition, high levels of organic (16.9 μg m⁻³) and elemental carbon (4.2 μg m⁻³) were found. Correlations between aerosol carbon and Br, Pb, NO and NMHC (all > 0.8) confirm that gasoline and diesel powered vehicles are one of the major sources of pollution in the region. Correlations between RP and Al, Si, K, Ca and Fe also suggest that soil aerosols contribute to the high RP concentrations. Enrichment factors for the RP samples relative to the composition of soil in the Athens basin indentify major contributions from vehicles (Pb and Br) and industrial operations (S, Ti, Mn, Fe, Ni, Cu, Zn). Based on these results, a Chemical Mass Balance receptor model was applied to each of the 27 samples and the contributions to RP from soil (4.5 %), vehicles (20.3 %), steel industries (4.6. %) and cement plant emissions (3.2 %) estimated. Other major components of the RP were SO₄²⁻ (13.0 %) and organic carbon from non-vehicle and industrial sources (15.5 %).     

The personal,indoor and outdoor concentrations of PM-10 measured in an industrial community during the winter

The concentrations of PM-10 were measured for 2 weeks in the winter of 1988 as part of the Total Human Environmental Exposure Study (THEES). Samples were taken simultaneously in a small city, Phillipsburg, NJ for outdoor and indoor microenvironments, and with personal monitors on non-smokers. There were four outdoor sites, eight indoor sites and fourteen individuals wearing personal monitors. The mean concentrations were 66, 48 and 42 μg m⁻³ for the personal, outdoor and indoor sites, respectively, with the personal samplers having 8.8% of the 24h averages above 150 μg m⁻³. The higher outdoor averages with respect to indoors were suspected to be related to more prevalent outdoor sources of coarse particles < 10 μm in diameter, and the lack of residential smokers to contribute to the indoor respirable subfraction. There was one day during the period when all the outdoor sites exceeded the 24 h PM-10 standard. Increased outdoor levels were also reflected in elevated indoor samples and the personal samples on that day. These would be a result of direct outdoor exposures and the penetration of outdoor PM-10 to the indoors.     

滨海城市气溶胶中颗粒态汞的分布特征

与气溶胶颗粒相结合的汞,即颗粒态汞,不仅对人体健康及生态环境产生一定的危害,而且在汞的生物地球化学过程扮演重要角色.以我国东南滨海城市厦门市为研究对象,采集郊区、居民区、旅游区、工业区和背景区四季(2008年10月～2009年8月)的PM2.5、PM10和TSP样品,基于塞曼原子吸收法的俄罗斯LumexRA-915+汞分析仪对大气不同粒径颗粒物中颗粒态汞进行了测试.结果表明,厦门市大气不同粒径颗粒物中汞的含量均表现为冬、春两季的浓度明显高于夏、秋两季;春、夏、秋、冬四季细颗粒物(PM2.5)中的含量分别为(51.46±19.28)、(42.41±12.74)、(38.38±6.08)和(127.23±33.70)pg/m3.不同粒径颗粒物中汞主要分布在PM2.5中,占到颗粒物态汞的42.48%～67.87%,表明细粒子富集汞的能力较强.不同功能区颗粒态汞的浓度分布趋势为背景区居民区旅游区工业区郊区,说明颗粒态汞浓度的空间分布特征与采样点的环境功能密切相关.总体而言,滨海城市大气颗粒态汞含量较低;PM2.5对颗粒态汞的富集明显高于PM10和TSP,表明对颗粒态汞的控制应集中在细颗粒物污染上.     

Soil crust formation by dust deposition at Shaartuz,Tadzhik, S.S.R.

The shrub-steppe area near Shaartuz, Tadzhik, S.S.R., is shown to be a net accumulator of dust despite being an occasional source of dust. For the accumulation of the dust to form the observed surface crust, a net deposition of about 290–490 g m⁻² yr⁻¹ of particles smaller than 20 μm is required, depending on the duration of the deposition period. The particles smaller than 20 μm are mixed with particles brought up from the sandy material below the surface crust by bioturbation and are incorporated into the surface crust. Measurements during the 16 and 20 September 1989 dust storms provided a total deposition of 41.1 g m⁻² of particles smaller than 20 μm. Because 10–30 dust storms are observed at Shaartuz, the measured average dust storm deposition would yield 206–617 g m⁻² yr⁻¹. This range of deposition is of the order of that needed to provide a mass balance for the observed crust formation. Cryptogams (including algae, lichen, and moss) and rainwater are the main agents of incorporation of the aeolian dust into a stable soil crust. The role that the vascular plants played at the Shaartuz site was to reduce the rate of soil movement to levels where the cryptogamic crusting was possible. the observed mechanisms of dust deposition followed by crust incorporation are possibly an important processes in loess formation in Central Asia.     

A chemical characterization of atmospheric aerosol in Sapporo

Monthly mean chemical composition of aerosol with diameter less than 8 μm was identified in Sapporo in 1982. The mass of aerosol was made up of nine components: elemental C, organics, SO₄²⁻, NO₃⁻, NH₄⁺, Cl⁻, Na⁺, soil particles and water. The concentrations of carbonaceous particles (elemental C and organics) was relatively high (12.7–16.0μ m⁻³) in autumn and winter (October–February) due to emission from domestic heating and comprised 36–41% of total aerosol mass. Higher concentration of soil particles was observed in spring (March–May) (9.7–13.1 μg m⁻³) and comprised 22–29% of total aerosol mass due to suspension by strong wind. On the other hand, the concentration of excess SO₄²⁻ (non-sea salt SO₄²⁻), which ranged from 2.6–5.2 μg m⁻³, did not change remarkably with season, and the fraction of excess sulfate increased to 21% in summer (July–August) probably due to photochemical transformation from SO₂. Nitrate concentration was far less than that of SO₄²⁻ throughout the year in Sapporo.     

Characteristics of airborne particles inside southern California museums

The concentrations and chemical composition of suspended particulate matter were measured in both the fine and total size modes inside and outside five southern California museums over summer and winter periods. The seasonally averaged indoor/outdoor ratios for particulate matter mass concentrations ranged from 0.16 to 0.96 for fine particles and from 0.06 to 0.53 for coarse particles, with the lower values observed for buildings with sophisticated ventilation systems which include filters for particulate matter removal. Museums with deliberate particle filtration systems showed indoor fine particle concentrations generally averaging less than 10 μg m⁻³. One museum with no environmental control system showed indoor fine particle concentrations averaging nearly 60 μg m⁻³ in winter and coarse particle concentrations in the 30–40 μg m⁻³ range. Analyses of indoor vs outdoor concentrations of major chemical species indicated that indoor sources of organic matter may exist at all sites, but that none of the other measured species appear to have major indoor sources at the museums studied. Significant fractions of the dark-colored fine elemental (black) carbon and soil dust particles present in outdoor air are able to penetrate to the indoor atmosphere of the museums studied, and may constitute a soiling hazard to works of art displayed in museums.     

Size distribution measurements of suspended particulate matter in Ponce,Puerto Rico

Size distribution measurements using a high volume sampler with a cascade impactor have been obtained for the city of Ponce, Puerto Rico from 1985 to 1987. The data indicate that the concentration of particles < 2 μm in diameter remained constant during the sampling period while the concentration of particles > 7 μm showed time variations. Aerosol from this area is greatly composed of particles > 7 μm in diameter, they accounted for over 45% of the Total Suspended Particulate (TSP) of this area. Over 75% of the aerosol concentration is from particles > 3.3 μm, approximately only 20% of the aerosol concentration is from particles < 2 μm in diameter. A linear relationship was observed between the different particle size and the TSP, except for those particles < 1.1 μm in size. The size distribution and its time variation are explained in terms of local sources such as agriculatural burning, natural contributions and industrial activities, as well as contribution from the Sahara haze that crosses the Atlantic from Africa and reaches the Caribbean region during the summer.     

Patterns of daily exposure to TSP and CO in the Garhwal Himalaya

Daily integrated exposure to TSP and CO was assessed by personal and stationary sampling of air in six microenvironments. Time-budget surveys were conducted to determine how much time four population groups (adult women, children, adult men and youths) spend in these microenvironments. Burning of biofuels in traditional unvented cookstoves is the most important anthropogenic source of pollutants in the study area—a rural and hilly region in the Garhwal Himalaya.Concentrations of pollutants measured at the time of cooking were found to be very high but comparable to those measured in the Indian plains (5.6 mg m⁻³ and 21 ppm for TSP and CO, respectively). The daily exposure of adult women to TSP and CO was estimated to be 37 mg h m⁻³ and 110 ppm h, respectively. Daily exposure, within each of the four population groups, was found to be very uniform across individuals for both the pollutants. Patterns of concentrations and daily exposure, as influenced by the time of the day, season and altitude are discussed.     

Spatial and temporal patterns in summertime sulfate aerosol acidity and neutralization within a metropolitan area

A study of sulfate aerosol acidity in Metropolitan Toronto was conducted during the summer of 1986. Fine-fraction aerosol (<2.5-μm) were collected using Teflon membrane filters and analyzed for major ionic species (H⁺, NH⁺₄, NO⁻₃, SO²⁻₄). Samples were collected for 6 weeks at three study sites: one in the Center City and the others 13 km (WNW) and 20 km (NE) away. There were very strong correlations among the three sites with respect to measured aerosol species (r² > 0.9 for 24-h data). However, spatial variations in the magnitude of aerosol acidity were observed during sulfate episodes. For example, the peak concentrations for all sites occurred on 25–26 July 1986. While the 24-h data for sulfate were quite uniform at the three sites (34, 34 and 35 μg m⁻³), H⁺ concentrations were 9.4, 8.3 and 6.0 μg m⁻³ (as H₂SO₄) for the NE, WNW and Center City sites, respectively. For most of the summertime episodes, the downtown area also had lower aerosol acidity compared to the two sites in suburban areas.     

Trace metals in atmospheric fine particles in one industrial urban city: Spatial variations, sources, and health implications

Trace metals in PM2.5were measured at one industrial site and one urban site during September, 2010 in Ji'nan, eastern China. Individual aerosol particles and PM2.5samples were collected concurrently at both sites. Mass concentrations of eleven trace metals(i.e., Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, and Pb) and one metalloid(i.e., As) were measured by inductively coupled plasma atomic emission spectroscopy(ICP-AES). The result shows that mass concentrations of PM2.5(130 μg/m3) and trace metals(4.03 μg/m3) at the industrial site were 1.3 times and 1.7 times higher than those at the urban site, respectively, indicating that industrial activities nearby the city can emit trace metals into the surrounding atmosphere. Fe concentrations were the highest among all the measured trace metals at both sites, with concentrations of 1.04 μg/m3at the urban site and 2.41 μg/m3at the industrial site, respectively. In addition, Pb showed the highest enrichment factors at both sites, suggesting the emissions from anthropogenic activities existed around the city. Correlation coefcient analysis and principal component analysis revealed that Cu, Fe, Mn, Pb, and Zn were originated from vehicular trafc and industrial emissions at both sites; As, Cr, and part of Pb from coal-fired power plant; Ba and Ti from natural soil. Based on the transmission electron microscopy analysis, we found that most of the trace metals were internally mixed with secondary sulfate/organic particles. These internally mixed trace metals in the urban air may have diferent toxic abilities compared with externally mixed trace metals.     

Vapor adsorption artifact in the sampling of organic aerosol: Face velocity effects

The concentration (μgC m⁻³) of aerosol organic carbon as determined by collection with quartz fiber filters was found to exhibit a significant decrease with increasing filter face velocity. A similar face velocity dependence was found for organic carbon on back-up quartz fiber filters behind either quartz fiber front filters (QQ combination) or Teflon membrane front filters (TQ combination). Additionally, the concentration of organic carbon on the back-up filter in the TQ combination was always greater than on the back-up filter in the QQ combination. The most likely explanation for these observations is the adsorption or organic vapors onto the filter medium itself. The amount of organic carbon adsorbed onto the quartz fiber front filter can be approximated by measuring the amount of organic carbon on a quartz fiber back-up filter behind a Teflon front filter with both filter combinations sampling at the same face velocity. Making the correction in such a manner removes most of the face velocity dependence inthe resultant concentrations. For 24 h sampling in Portland, Oregon, at a face velocity of 40 cm s⁻¹, the correction exceeded 50% for uncorrected organic carbon concentrations of 2 μgC m⁻³ but decreased to 15% at 16 μgC m⁻³.     

厦门海沧区PM2.5中金属元素污染评价及来源分析

为了了解金属元素的污染特征和潜在来源,以及重金属元素的风险水平,本研究于2015年4月至2016年1月采集了厦门海沧区不同类型站点四季大气PM_(2.5)样品348份,用X射线荧光分析仪(XRF)测定了其中K、Ca、Na、Mg、Al、Zn、Cu、Fe、Ti、As、V、Mn、Ba、Co等14种金属元素的质量浓度.本研究分析了码头、生活区、工业区和背景区这4个类型站点PM_(2.5)中金属元素的时空分布特征,综合利用富集因子法和健康风险评价模型进行了金属元素的污染评价,并采用相关性分析、主成分分析和后向气团轨迹初步探讨了金属元素的来源.结果表明,采样期间厦门海沧区PM_(2.5)中14种金属元素总质量浓度在PM_(2.5)中的占比为5.4%~10.6%.金属元素总质量浓度的时空变化特征与PM_(2.5)的较为一致,均表现为春冬季浓度高于夏秋季,海润码头和新阳工业区高于海沧分局和市委党校.而夏季海润码头和海沧分局PM_(2.5)日均值超标率较高的现象,与海润码头作业以及风向有关.新阳工业区Zn的质量浓度最高,市委党校次之;海润码头V的质量浓度最高,夏季海沧分局易出现V的浓度高值;均说明污染源站点(新阳工业区和海润码头)排放的污染物对其附近站点的金属元素质量浓度产生了影响.K质量浓度冬季最高,As超标现象出现在冬季和春季,说明冬季生物质燃烧以及燃煤等燃烧排放对大气污染的影响较为严重.Cu、Zn、As、Co、Na和Mn在各站点的富集因子范围为67~8449,富集均较严重.非致癌重金属Zn、Cu、Mn风险值之和低于一般可接受的风险水平(1×10~(-6)a~(-1)),其中Mn对总风险值的贡献范围为74%~88%.综合相关性分析和主成分分析结果表明,厦门海沧区PM_(2.5)中金属元素主要来源于地面扬尘、机动车排放、燃煤和工业排放以及船舶排放,各来源分别可以解释变量的34.5%、12.5%、10.6%、7.8%.后向气团轨迹表明春、秋和冬季均受到局地气团的影响,而夏季气团运动相对较强;春冬季途经长三角内陆的气团可能导致PM_(2.5)浓度偏高.