Carbonyl compounds and dissolved organic carbon in rainwater of an urban atmosphere

This study investigates the occurrence of carbonyl compounds in rainwater at the city of Thessaloniki, Northern Greece. The concentrations of carbonyl compounds (as sum of 14 compounds) ranged from 21.8 to 592 μg/L, mean concentration 119 μg/L. Formaldehyde, acetaldehyde, hexanal, glyoxal, and methylglyoxal were the dominant compounds. DOC concentrations in rainwater ranged from 0.46 to 21.3 mg/L. UV–Vis and fluorescence spectra characteristics showed variation among rain events. Carbonyl compounds were negatively correlated with temperature exhibited relatively higher concentrations in cold season. They also influenced by storm origin with higher concentrations under terrestrial air masses. Calm conditions enhance the concentrations of DOC. Wash out is an effective removal mechanism of DOC.     

Quantification of sources of PCBs to the atmosphere in urban areas: A comparison of cities in North America, Western Europe and former Yugoslavia

We present estimated emission source strengths of seven polychlorinated biphenyl (PCB) congeners for Banja Luka, a city that was affected by the civil war in Bosnia and Hercegovina (former Yugoslavia) in the 1990s. These emission estimates are compared to PCB emission rates estimated for the cities of Zurich, Switzerland, and Chicago, USA using an approach that combines multimedia mass balance modeling and measurement data. Our modeled per-capita emission estimates for Banja Luka are lower by a factor of ten than those for Zurich and Chicago, which are similar. This indicates that the sources of PCB emissions in Banja Luka are likely to be weaker than in the Western European and North American cities which show relatively high PCB emissions. Our emission rates from the three cities agree within a factor of ten with emission estimates from a global PCB emission inventory derived from production and usage estimates and emission factors.     

Volatile organic compounds (VOCs) in urban atmosphere of Hong Kong

The assessment of volatile organic compounds (VOCs) has become a major issue of air quality network monitoring in Hong Kong. This study is aimed to identify, quantify and characterize volatile organic compounds (VOCs) in different urban areas in Hong Kong. The spatial distribution, temporal variation as well as correlations of VOCs at five roadside sampling sites were discussed. Twelve VOCs were routinely detected in urban areas (Mong Kok, Kwai Chung, Yuen Long and Causeway Bay). The concentrations of VOCs ranged from undetectable to 1396 microg/m3. Among all of the VOC species, toluene has the highest concentration. Benzene, toluene, ethylbenzene and xylenes (BTEX) were the major constituents (more than 60% in composition of total VOC detected), mainly contributed from mobile sources. Similar to other Asian cities, the VOC levels measured in urban areas in Hong Kong were affected both by automobile exhaust and industrial emissions. High toluene to benzene ratios (average T/B ratio = 5) was also found in Hong Kong as in other Asian cities. In general, VOC concentrations in the winter were higher than those measured in the summer (winter to summer ratio > 1). As toluene and benzene were the major pollutants from vehicle exhausts, there is a necessity to tighten automobile emission standards in Hong Kong.     

Seasonal variation and source estimation of organic compounds in urban aerosol of Augsburg, Germany

This study reports a general assessment of the organic composition of the PM_2.5 samples collected in the city of Augsburg, Germany in a summer (August-September 2007) and a winter (February-March 2008) campaign of 36 and 30 days, respectively. The samples were directly submitted to in-situ derivatisation thermal desorption gas chromatography coupled with time of flight mass spectrometry (IDTD-GC-TOFMS) to simultaneously determine the concentrations of many classes of molecular markers, such as n-alkanes, iso- and anteiso-alkanes, polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs, n-alkanoic acids, alcohols, saccharides and others.The PCA analysis of the data identified the contributions of three emission sources, i.e., combustion sources, including fossil fuel emissions and biomass burning, vegetative detritus, and oxidized PAHs. The PM chemical composition shows seasonal trend: winter is characterized by high contribution of petroleum/wood combustion while the vegetative component and atmospheric photochemical reactions are predominant in the hot season.     

Age- and sex-based comparative distribution of selected metals in the scalp hair of an urban population from two cities in Pakistan

Concentrations of Cu, Zn, Pb and Ni in the scalp hair of male and female donors, with an age range of 6-60 years, were determined by ICP atomic emission spectroscopy. The donors were drawn from the densely populated city of Lahore and the relatively less-populated capital city of Islamabad for comparative evaluation of the metal levels in relation to age, sex and location. Linear regression analyses and correlation between paired metals indicated a positive correlation between Cu and Zn for both sexes ( [Formula: see text] ) and between Pb and Ni ( [Formula: see text] ) for males and females of Lahore. Metal concentrations varied between the two cities and the two sexes. The highest mean concentration was found for Zn at 180.5 microg g(-1) for males and 202.4 microg g(-1) for females from Lahore, while for counterparts from Islamabad the values were 105.2 microg g(-1) and 206.6 microg g(-1). Copper showed an identical mean concentration (20.8 microg g(-1)) in the hair of both males and females from Lahore; however, relatively lower mean concentrations (7.7 and 10.8 microg g(-1)) were observed for donors from Islamabad. Mean Pb concentrations in hair of male donors from Lahore and Islamabad were 9.4 and 7.0 microg g(-1), respectively; in female groups the concentrations were 14.3 and 5.7 microg g(-1), respectively. Ni showed the lowest concentration range (4.3-4.5 microg g(-1)) of all the four metals for subjects from Lahore, and this was higher than the corresponding range (2.0-3.2 microg g(-1)) for subjects from Islamabad. The findings are discussed in relation to the available data from the literature.     

Seasonal variation of the size distribution of urban particulate matter and associated organic pollutants in the ambient air

Size-segregated samples of urban particulate matter (<0.95, 0.95–1.5, 1.5–3.0, 3.0–7.5, >7.5 μm) were collected in Thessaloniki, northern Greece, during winter and summer of 2007–2008, in order to study the size distribution of organic compounds such as polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs) including n-alkanes and the isoprenoids pristane and phytane, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). All organic compounds were accumulated in the particle size fraction <0.95 μm particularly in the cold season. Particulate matter displayed a bimodal normalized distribution in both seasons with a stable coarse mode located at 3.0–7.5 μm and a fine mode shifting from 0.95–1.5 μm in winter to <0.95 μm in summer. Unimodal normalized distributions, predominant at 0.95–1.5 μm size range, were found for most organic compounds in both seasons, suggesting gas-to-particle transformation after emission. A second minor mode at larger particles (3.0–7.5 μm) was observed for C₁₉ and certain OCPs suggesting redistribution due to volatilization and condensation.     

Oxygenated volatile organic compounds (OVOCs) at an urban background site in Zürich (Europe): Seasonal variation and source allocation

Twenty-one oxygenated volatile organic compounds (OVOCs) were measured in four seasonal campaigns at an urban background site in Zürich (Switzerland) with a newly developed double adsorbent sampling unit coupled to a gas chromatograph–mass spectrometer (GC–MS). In addition, selected non-methane hydrocarbons (NMHCs) were measured, as well as formaldehyde in the summer and winter campaign. The most abundant compound measured in all seasons was ethanol, with peak values of more than 60 ppb. Its seasonal variation with a lower mean value in summer compared to that in winter implied mostly anthropogenic sources. In contrast, compounds with additional biogenic sources, or compounds known to be produced in the troposphere by oxidation processes, had seasonal maxima in summer (e.g. methanol, acetone, formaldehyde, methacrolein and 2-butenone (methyl vinyl ketone, MVK)).For the OVOCs it was estimated that local sources contributed 40% and 49% to the mixing ratios of the measured compounds in summer and in winter, respectively. Combustion was estimated to contribute 75% to these local sources independent of the season. About 50% of both the OVOC and NMHC levels in Zürich could be explained by the regional background, which included regional biogenic and anthropogenic sources in addition to secondary production. Industrial sources were identified for acetone, butanone (methyl ethyl ketone, MEK), n-propanol, iso-propanol, n-butanol, ethyl acetate and butyl acetate.     

Ambient levels of volatile organic compounds in the atmosphere of Greater Cairo

Ambient volatile organic compounds (VOCs) samples were collected at three locations, two in urban areas in Greater Cairo (Ramsis and Haram) and background one in rural area in Menofiya province (Kafr El-Akram), during the period of June, 2004–August, 2004. The highest concentrations of VOCs were found in Ramsis, whereas the lowest concentrations were detected in Kafr El-Akram, and the difference in mean concentrations were statistically significant (p<0.001). Among all of the measured VOCs species, the contribution of individual VOC to the total VOCs concentration were very similar in Ramsis and Haram locations, toluene was the most abundant compound followed by (m, p)-xylene. This similarity implies a similar emission sources of VOCs in both urban locations, vehicle exhausts are the dominant one. Greater Cairo has high levels of volatile aromatic hydrocarbons compared with many polluted cities in the world. The BTEX (benzene: toluene: ethylbenzene: xylenes) concentration ratios were (2.01:4.94:1:4.95), (2.03:4.91:1:4.87) and (2.31:2.98:1:2.59) in Ramsis, Haram and Kafr El-Akram, respectively. The average toluene/benzene (T/B), (m, p)-xylene/benzene ((m, p)-X/B) and o-xylene/benzene (o-X/B) concentration ratios were 2.45, 1.61and 0.85, respectively in Ramsis and 2.42, 1.61 and 0.78, respectively in Haram. The ratios in both urban locations were of the same magnitude and close to those obtained from automotive exhausts, indicating that the ambient BTEX originate mainly from motor vehicle emissions. However, the (T/B), ((m, p)-X/B) and (o-X/B) concentration ratios were 1.29, 0.71 and 0.41 in Kafr El-Akram, respectively. These ratios were lower than those found in Ramsis and Haram locations and in automotive exhaust, suggesting that the BTEX in Kafr El-Akram do not come from a local source and are exclusively results from the diffusion and dispersion of VOCs produced from the traffic density in the surrounding cities. Significant positive correlation coefficients (p<0.001) were found between the concentrations of BTEX compounds at the three sampling locations. The diurnal variation of VOCs concentrations in Ramsis location showed two daily peaks linked to traffic density.     

Concentrations and fluxes of organic compounds in the atmosphere of the Swedish west coast

Measurements of organic compounds in air and deposition have been carried out in parallel on the Swedish west coast. In this investigation the importance of long-range transport for the occurrence of organic compounds in deposition has been studied. Air samples were collected using a high volume sampler (HVS) and the deposition was sampled on a 1 m² Teflon-coated horizontal surface with runoff for the precipitation to an adsorbent. The samples were analyzed in order to identify and quantify different semivolatile compounds such as PAH and petrogenic hydrocarbons and chlorinated compounds such as PCB, HCH and HCB. Qualitative differences between the content of organic compounds in air and deposition during periods with varying levels of air pollution and different meteorological conditions have been studied and a comparison with other air pollutants, such as soot, has been carried out. The results of the measurements show that deposition of PAH and other hydrocarbons takes place continuously but the greatest amounts are measured in the deposition in connection with episodes together with heavy precipitation. The highest concentrations of PCB and HCH in the air were obtained during a warm dry period in May and the greatest amounts were deposited in a period in May with heavy precipitation.     

On the origin of water-soluble organic tracer compounds in fine aerosols in two cities: the case of Los Angeles and Barcelona

Water-soluble organic compounds (WSOCs), represented by anhydro-saccharides, dicarboxylic acids, and polyols, were analyzed by gas chromatography interfaced to mass spectrometry in extracts from 103 PM₁ and 22 PM_2.5 filter samples collected in an urban background and road site in Barcelona (Spain) and an urban background site in Los Angeles (USA), respectively, during 1-month intensive sampling campaigns in 2010. Both locations have similar Mediterranean climates, with relatively high solar radiation and frequent anti-cyclonic conditions, and are influenced by a complex mixture of emission sources. Multivariate curve resolution-alternating least squares analyses were applied on the database in order to resolve differences and similarities in WSOC compositions in the studied sites. Five consistent clusters for the analyzed compounds were obtained, representing primary regional biomass burning organic carbon, three secondary organic components (aged SOC, isoprene SOC, and α-pinene SOC), and a less clear component, called urban oxygenated organic carbon. This last component is probably influenced by in situ urban activities, such as food cooking and traffic emissions and oxidation processes.     

Hourly and daily patterns of particle-phase organic and elemental carbon concentrations in the urban atmosphere

Two semicontinuous elemental and organic carbon analyzers along with daily integrated samplers, which were used for laboratory elemental and organic carbon analysis, were operated to measure PM2.5 organic carbon (OC) and elemental carbon (EC) for the entire year of 2002 at the St. Louis Midwest Supersite. The annual-average denuded OC and EC concentrations were 3.88 and 0.7 microg/m3, respectively. A comparison of the 24-hr average denuded and undenuded OC measurements showed a positive bias for the undenuded OC measurement that was best represented by a positive intercept of 0.34 +/- 0.1 microg/m3 and a slope of 1.06 +/- 0.02, with an R2 of 0.91. The full year of daily EC and OC measurements was used to demonstrate that a one-in-six-day sampling strategy at this site accurately represents the annual average concentrations. Although fine particle OC concentrations did not correlate with day of the week, EC concentrations showed a significant weekly pattern, with the highest concentration during the middle of the workweek and the lowest concentration on Sundays. Hourly EC and OC measurements yielded average diurnal patterns for the EC to OC ratio that peaked during morning rush hour traffic on weekdays but not on weekends.     

The distribution of particle-phase organic compounds in the atmosphere and their use for source apportionment during the Southern California Children''s Health Study

Atmospheric particulate matter (PM) samples from 12 sites in southern California, collected as part of the Southern California Children's Health Study (SCCHS), were analyzed using gas chromatography/mass spectrometry (GC/MS) techniques. Ninety-four organic compounds were quantified in these samples, including n-alkanes, fatty acids, polycyclic aromatic hydrocarbons (PAH), hopanes, steranes, aromatic diacids, aliphatic diacids, resin acids, methoxyphenols, and levoglucosan. Annual average concentrations of all detected compounds, as well as average concentrations for three seasonal periods, were determined at all 12 sites for the calendar year of 1995. These measurements provide important information about the seasonal and spatial distribution of particle-phase organic compounds in southern California. Also, co-located samples from one site were analyzed to assess precision of measurement. Excellent agreement was observed between annual average concentrations for the broad range of organic compounds measured in this study. Measured concentrations from the 12 sampling sites were used in a previously developed molecular-marker source apportionment model to quantify the primary source contributions to the PM10 organic carbon and mass concentrations at these 12 sites. Source contributions to atmospheric PM from six important air pollution sources were quantified: gasoline-powered motor vehicle exhaust, diesel vehicle exhaust, wood smoke, vegetative detritus, tire wear, and natural gas combustion. Important trends in the seasonal and spatial patterns of the impact of these six sources were observed. In addition, contributions from meat smoke were detected in selected samples.     

Seasonal and spatial occurrence and distribution of atmospheric polycyclic aromatic hydrocarbons (PAHs) in rural and urban areas of the North Chinese Plain

Passive air sampling (PAS) was employed to study the occurrence of gaseous and particle-bound PAHs in the North Chinese Plain. The averaged concentrations of gaseous and particle-bound PAHs were 485 ± 209 ng/m³ and 267 ± 161 ng/m³, respectively. The PAHs concentrations at urban sites were generally higher than those at rural ones with ratios <1.5 in spring, summer and fall, but differences between them were not significant for the wintertime and annually averaged concentrations. This urban-rural distribution pattern was related to the PAHs emission sources. PAHs spatial variation can be partially (49%) explained by emission with a simple linear regression method. Both the gaseous and particle-bound PAHs were highest in winter and lowest in summer, with winter/summer ratios of 1.8 and 8, respectively. Emission strength was the most important factor for the seasonality.     

A comparison of extinction and size distribution data measured at two urban sites in the U.S. and Europe

Extinction coefficients and mass size distributions were measured at St. Louis, MO. and at Vienna, Austria with the same instrumentation (an 11-wavelength automated telephotometer and an 8-stage low pressure cascade impactor, both designed at the University of Vienna). A comparison between the sites gave lower extinction coefficients, mean aerodynamic diameters, standard deviations and mass concentrations of the accumulation mode at the St. Louis site and a similar dependence of extinction on relative humidity.     

Persistent organic pollutants in the atmosphere from urban and industrial environments in the Rhine Valley: PCBs, PCDD/Fs

Polychlorinated biphenyls (PCBs) and polychlorinated dibenzodioxin and furan (PCDD/F) concentrations in the atmosphere were analysed using passive air samplers (PAS) close to the Rhine River between France and Germany. Collectors were placed in industrial, urban, rural and remote areas (Vosges Mountains) between March 2009 and August 2010, and the mean PCB concentrations (sum of 22 congeners) were 3.3, 3.9, 4.1 and 1.4 ng?PAS^?1?day^?1, respectively. Two events during the sampling period were observed in April 2009 and February–March 2010 with the highest PCB concentrations found in the industrial area (19.6 ng?PAS^?1?day^?1). PCDD/F level were measured during these periods, and the maximum concentration observed was from 37.5 fg?WHO?PAS^?1?day^?1     

Priority volatile organic compounds in surface waters of the southern North Sea

The occurrence of 25 volatile organic compounds (VOCs) was studied from April 1998 to October 2000 in the southern North Sea. Target VOCs were selected from lists of priority pollutants for the marine environment and included, e.g., chlorinated short-chain hydrocarbons (CHCs), monocyclic aromatic hydrocarbons (MAHs), and chlorinated monocyclic aromatic hydrocarbons (CMAHs). Water samples were taken from the Channel, the Belgian Continental Shelf, the mouth of the Scheldt estuary and the Southern Bight, and were analysed by purge-and-trap and high-resolution gas chromatography-mass spectrometry. All data were produced by analyses deemed 'in control' by a rigorous quality assurance/quality control program provided by QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe). Chloroform and trichloroethene were commonly detected at concentrations up to 1900 and 270 ng l(-1), respectively. The other CHCs were generally found below 5 ng l(-1), and rarely exceeded 10 ng l(-1). Concentrations of MAHs were at least one order of magnitude higher than those of the CHCs. The higher levels were attributed to anthropogenic emissions from oil-related activities in coastal areas. CMAHs, except chlorobenzene and 1,4-dichlorobenzene, were hardly detected in North Sea waters. The levels of several CHCs and MAHs were shown to decrease compared to previous investigations in 1994-1995, probably as a result of on-going emission reduction efforts. The occurrence of 1,1,1-trichloroethane, for instance, was substantially reduced since the Montreal Protocol was implemented in 1995.     

Seasonal and spatial distribution of metals in surface sediment of an urban estuary

Aquatic pollution by metals is of concern because of various toxic effects to marine life. The Tolka Estuary, Co. Dublin, Ireland, is a typical Irish urban estuary. It has a significant metal loading originating from the urban environment. Results of a 25month analysis of cadmium, copper, lead and zinc spatial and temporal distribution over 10 sample locations in this estuary are presented in this paper. Metal concentrations were analysed using differential pulse polarography. Significant seasonal and spatial trends in metal distribution were observed over the 25months. Sediment metal concentrations gradually increased (30-120%) in spring to a maximum at the end of summer which was followed by a decrease in winter months (30-60%). Sediment organic matter (OM) concentrations exhibited similar seasonal trends and a positive correlation between OM and metal distributions was observed, implying OM had an influence on metal distributions over time.     

The occurrence of chlorinated and other organic trace compounds in urban air

The concentrations of 42 chlorinated hydrocarbons (boiling point range from 61 °C to 400 °C) and those of 16 selected volatile hydrocarbons were simultaneously measured in ambient air during the period of one year. The measurements were carried out at 12 sites with different air qualities in the city of Hamburg (FRG). Annual means, medians and peak concentrations are presented. Analyses of the concentration distributions and a comparison with emission data show that traffic is the dominant source of hydrocarbons, whereas chlorinated hydrocarbons are predominantly emitted by industrial sources. This results in a fairly uniform urban pattern of hydrocarbons, but highly variable concentrations of low boiling halogenated compounds.     

Effect of dissolved organic carbon on the environmental distribution of nonpolar organic compounds

The effect of dissolved organic carbon on the process of pollutant sorption to aquatic sediments was studied using sediments from the Boonton Reservoir/Rockaway River system in northern New Jersey. Addition of DOC to the aqueous phase reduced the sorption of DDT to sediments, but had no effect on the sorption of Lindane. The effect of the DOC is to increase the amount of DDT in the soluble phase and enable transport of the compound throughout an aquatic system. The apparent influence of DOC on the equilibrium distribution of organic compounds is illustrated by modifying an existing environmental model.     

A detailed investigation of ambient aerosol composition and size distribution in an urban atmosphere

This research was executed between March 2009 and March 2010 to monitor particulate matter size distribution and its composition in Istanbul. Particulate matter composition was determined using ion chromatography and inductively coupled plasma optical emission spectrometry. The sampling point is adjacent to a crowded road and the Bosporus Strait. Two prevailing particulate modes are found throughout PM₁₀ by sampling with a nine-stage low-volume cascade impactor. First mode in the fine mode is found to be between 0.43 and 0.65 μm, whereas the other peak was observed between 3.3 and 4.7 μm, referring to the coarse mode. The mean PM₁₀ concentration was determined as 41.2 μg/m³, with a standard deviation of 16.92 μg/m³. PM_0.43 had the highest mean concentration value of 10.67 μg/m³, making up nearly one fourth of the total PM₁₀ mass. For determining the effect of traffic on particulate matter (PM) composition and distribution, four different sampling cycles were applied: entire day, nighttime, rush hour, and rush hour at weekdays. SO ₄ ^?2 and organic carbon/elemental carbon proportions are found to be lower in night samples, representing a decrease in traffic. The long-range transports of dust storms were observed during the sampling periods. Their effects were determined analytically and their route models were run by the HYSPLIT model and validated through satellite photographs taken by the NASA Earth Observatory.