- Email: [email protected]
Organic composition of Seville aerosols
Organic Geochemistry Organic Geochemistry 37 (2006) 2019–2025 www.elsevier.com/locate/orggeochem
Organic composition of Seville aerosols J. Reyes, B. Hermosin, C. Saiz-Jimenez
*
Instituto de Recursos Naturales y Agrobiologia, CSIC, Apartado 1052, 41080 Sevilla, Spain Available online 12 October 2006
Abstract The organic species present in the aerosols of the Seville atmosphere, sampled at different periods of the year, under distinct traffic regimes, are presented. The compounds are related to incomplete fuel combustion in vehicular exhausts. 2006 Elsevier Ltd. All rights reserved.
1. Introduction Urban air pollution is a major concern throughout Europe as industrial wastes, traffic congestion and over-crowding in cities create pollutants that significantly contribute to environmental damage and health problems. Urban aerosols generally consist of a mixture of lipid materials emitted locally along with the aged material that has been carried into the urban area by winds. Urban atmospheric environments contain many organic pollutants which are related to incomplete fuel combustion in domestic heating, industrial plants and vehicular exhausts, such as long-chain alkanes, monocarboxylic and dicarboxylic acids, polycyclic aromatic hydrocarbons (PAH), and terpenoids (Simoneit and Mazurek, 1981). In addition to organic compounds, carbonaceous matter (mainly elemental carbon) is common in urban environments. Buildings and monuments act as repositories of these airborne organic pollutants, which are entrapped at the stone surfaces as part of the developing black crusts. *
Corresponding author. E-mail address: [email protected] (C. Saiz-Jimenez).
Traffic congestion and air pollution are a major problem in the city of Seville with a historic centre with very narrow streets. For more than five decades, exhaust emissions from gasolineand diesel-powered vehicles contributed to the deterioration of the cathedral of Seville through the formation of black crusts (Saiz-Jimenez, 1993), a phenomenon that has also been described in other European cathedrals (Hermosin et al., 2004). In the last 25 years several reports on this topic and exhaustive analyses of deteriorated building materials from the cathedral of Seville were presented (Saiz-Jimenez and Bernier, 1981; Saiz-Jimenez and Garcia del Cura, 1991; Fobe et al., 1995). However, the characterization of the organic components of the aerosols, and its comparison with the organic fractions extracted from the black crusts formed on the building surfaces is far from complete (Grimalt et al., 1991). In this paper, we report on the organic compounds present in aerosols collected in a station located in the cathedral of Seville, at different periods and traffic regimes. These compounds are compared with those deposited on the stone surface of the same monument.
0146-6380/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.orggeochem.2006.08.006
2020
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025
2. Materials and methods 2.1. Sample collection Aerosols were collected in a high volume air sampler (Staplex Co., New York, USA, model TFIA-2) operating at a flow rate of 2 m3/min. The sampler was installed in the roof of the Assumption portal, cathedral of Seville, at about 20 m height, and facing the traffic-congested Constitution Avenue. Different traffic regimes were considered: Sampling A, in regular traffic conditions: from 11 to 14 June 2002 from 9.00 to 20.00. Vehicular traffic included buses, cars and mopeds. Sampling B, under partially restricted traffic conditions: from 24 to 30 March 2002, from 9.00 to 17.00. Vehicular traffic permitted only for cars and mopeds during the morning. Sampling C, under no traffic: from 24 to 30 March 2002. Sampling was carried out from 17.00 to 2.00, except for 29 March in which sampling continued from 2.00 to 8.00. No vehicular traffic, but continuous religious processions carrying thousands of candles occupied the street. Black crusts were collected from the Baptism portal during the cleaning and restoration works carried out in 2000 (sample D). This portal is at some 35 m from sampling station. The sampling area was located at 20 m height.
using a 30 m · 0.25 mm TRB-5HT column (film thickness 0.1 lm). The GC oven was programmed from 80 to 120 C at 30 C/min and then to 320 C. The final temperature was held for 20 min. In the analytical procedure followed in this work, the carboxylic acids were recovered as the corresponding methyl esters, and the hydroxyls as methoxyls. Throughout this paper they are referred to as acids and hydroxyls – their original forms – rather than as derivatized methyl esters and methoxyls. The compounds were identified by comparison of their mass spectra with a self-compiled data bank of compounds from a variety of samples (Saiz-Jimenez, 1993, 2003; Gavin˜o et al., 2004). In some cases, identification was achieved by computer analysis from a National Bureau of Standards library of about 107,886 spectra, with the computer matching being checked against standards whenever possible. 3. Results and discussion Great concentrations of gases and aerosols are reached in Constitution Avenue, a very narrow street delimited by the western fac¸ade of the cathedral of Seville (Fig. 1). This street routes all traffic to the city centre. A 1997 study estimated average daily traffic as 2200 buses, 7000 motorcycles and 13,600 cars (Saiz-Jimenez et al., 2004). Nowadays the figures could likely be higher. However, every
2.2. Analysis of compounds The analytical procedure for identification of compounds present in aerosols and black crusts was as follows. The bulk samples collected on the air filter were extracted in a Soxhlet apparatus with dichloromethane-methanol (2:1) for 72 h. The extracts were evaporated under vacuum at low temperature (below 40 C) and redissolved in dichloromethane-methanol (2:1). The resulting extract was fractionated using a silica column, eluted with hexane (fraction I), hexane-dichloromethane (1:1) (fraction II), dichloromethane (fraction III), and finally with methanol (fraction IV). Compounds present in fractions III and IV were methylated with trimethylsilyldiazomethane (TMSCHN2). In this paper, we will report on the study of fraction I containing the most characteristic series of compounds and molecular markers. For analysis, 2 ll of each fraction were injected in a Fisons gas chromatography–mass spectrometry (GC–MS) instrument, model GC 8000/MD 800,
Fig. 1. Constitution Avenue, a narrow street delimited by the western fac¸ade of the cathedral of Seville.
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025
year, during a few weeks near Holy Week, the Sevillian municipality introduces traffic regulations resulting in partial or total closure of the street to permit religious processions. A study of the chemical composition of aerosols sampled at different periods of the year under distinct traffic regimes is, therefore, possible. The inorganic data obtained in that sampling were reported by Cachier et al. (2004) who found that elemental carbon (EC) in Seville aerosols (sampling in the same station used in this study) was three times higher than in Florence cathedral and twice that in Paris (Saint Eustache church) or Milan cathedral. This was explained by the fact that Seville is heavily influenced by heavy-duty diesel buses which are known to produce predominantly fine EC particles. A preliminary sampling tour around the cathedral of Seville while recording particle number with a portable condensation nuclei counter showed that the background level was about 20,000 particles/ cm3 (Fig. 2). However, Constitution Avenue revealed concentrations as high as 329,000 particles/cm3. The high values corresponded to diesel bus routes on the street. This experiment illustrates the heavy air pollution and the deleterious effect of traffic channelling in the narrow Constitution Avenue, which enhances particulate pollution (Cachier et al., 2004).
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After sampling with the high volume air sampler, the filters were extracted with solvents and the total extracts analysed by GC–MS. The total ion current chromatogram traces (not shown) confirmed that the extracts contained a complex mixture of compounds dominated by n-fatty acids (C12–C18), aliphatic dicarboxylic acids (C8, C9), aromatic compounds (benzenecarboxylic acids) and nicotine. In addition, the series of n-alkanes (C13–C29) was evident. Many other compounds present in minor or trace amounts could be discerned. A further fractionation was necessary in order to separate specific series of compounds for source apportionments and to avoid overlapping and/or complex unresolved mixtures. Although four different fractions were obtained from the total extracts by column chromatography, here we will refer only to fraction I, which has significant diagnostic interest (e.g., biomarkers). Fig. 3 shows a selected ion mass chromatogram (m/z 85) for fraction I, indicating the distribution of n-alkanes in sampling A (no traffic restrictions), B (partial traffic restrictions) and C (no traffic). The traces are dominated (in decreasing order) by a large unresolved complex mixture (UCM) or ‘‘hump’’, with the main resolved components being n-alkanes. Isoprenoid hydrocarbons (pristane and phytane) were identified as well. While a similar
Fig. 2. Particle density around the cathedral. Bar denotes the Constitution Avenue transect. Higher peaks correspond to the transit of buses.
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RT Fig. 3. Ion mass chromatogram (m/z 85) of aerosols sampled at different traffic regimes (A–C) and cathedral black crusts (D). Numbers indicate carbon atoms of the corresponding n-alkane. P is pristane and F phytane.
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025
n-alkane distribution was observed in all the three chromatograms, differences in maximum at C29 for A, and at C27 for B and C, and in the intensity of the UCM formed by the presence of many overlapping peaks were evident. Similar patterns of n-alkanes maximising at C29 were reported for urban areas in Western United States aerosols (Simoneit, 1986). Fig. 3D shows the ion mass chromatogram trace (m/z 85) for fraction I obtained from black crusts collected from the Baptism portal. There, a bimodal distribution of n-alkanes was observed. The first part maximized at n-C21, and the second part of the series had a maximum at n-C29. Patterns of n-alkanes maximising at C21 were reported for diesel and gasoline engine exhausts and patterns maximising at C29 were typical of urban aerosols (Simoneit, 1985). Lubricating oil used in Sevillian buses showed a pattern maximising at C30 but diesel soot from the same buses presented a maximum at C20 (data not shown). The pronounced unresolved naphthenic hump in the aerosols obtained with no traffic restriction (A) was similar to that obtained from lubricating oils. These data indicated that n-alkanes present in black crusts seems to have a double imprint, from aerosols originated from uncombusted petroleum derivatives (gasoline, diesel) whereas the naphthenic hump with associated triterpenoid markers (see below) originated from lubricating oils. Other series of compounds found in fraction I of aerosol extracts and black crusts, such as alkylcyclohexanes, alkylbenzenes and alkylnaphthalenes will not be discussed here, as they are not source-specific, and are generally found in every combustion emission. Hopanes are molecular fossils present in crude petroleum. They have been used to trace the sources or identify the origin of petroleum derivatives. Simoneit (1985) proposed that hopanes could be used as tracers for motor vehicle exhaust particles in the atmosphere. Hopanes are present in the lubricating oil used by both gasoline- and diesel-powered motor vehicles (Cass, 1998) and have been reported to be common components of aerosols and black crusts (Saiz-Jimenez, 1993, 2003). Hopanes (Fig. 4) also eluted in fraction I of the aerosol extracts. These biomarkers were relatively easy to detect using ion monitoring at m/z 191, in spite of their low contributions to the fraction. The hopanes identified in the aerosols were 18a(H)22,29,30-trisnorhopane (1), 17a(H)-22,29,30-trisnorhopane (2), 17a(H),21b(H)-30-norhopane (3),
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17a(H),21b(H)-hopane (4), 17a(H),21b(H)-homohopane 22S (5), 17a(H),21b(H)-homohopane 22R (6), 17a(H),21b(H)-bishomohopane 22S (7), 17a(H), 21b(H)-bishomohopane 22R (8), 17a(H),21b(H)-trishomo hopane 22S (9), 17a(H),21b(H)-trishomohopane 22R (10), 17a(H),21b(H)-tetrakishomohopane 22S (11), 17a(H),21b(H)-tetrakishomohopane 22R (12), 17a(H),21b(H)-pentakishomohopane 22S (13), and 17a(H),21b(H)-pentakishomohopane 22R (14). This pattern of hopanes was similar to those reported for aerosol particles (Simoneit, 1985), crude oil (Philp, 1985), automobile and diesel engine exhausts (Fraser et al., 1999) and black crusts (Saiz-Jimenez, 1993, 2003). The presence of minor amounts of the isoprenoid hydrocarbons pristane and phytane and the hopanes indicates a petroleum source for these compounds. Interestingly, hopanes were not detected in fraction I of aerosols obtained when there was no traffic in the area (C) which clearly confirms that this series of compounds was emitted by motor vehicles. Grimalt et al. (1991) reported the close similarity between the organic composition of black crusts from the Holy Family church in Barcelona, Spain, and airborne particulates, collected by glass fibre filtration, and gas-phase organic compounds, obtained by polyurethane foam adsorption. These facts and the finding of carbonaceous particles entrapped in the voids of gypsum crystals (SaizJimenez and Bernier, 1981) demonstrated that the organic compounds present in the black crusts, covering the building stones in urban environments, are the result of a direct input of air pollutants, the buildings acting as non-selective surfaces passively entrapping all deposited aerosols and particulate matter, from whose analysis a source can be traced. A study of Sagebiel et al. (1997) illustrated the importance of diesel vehicles in the production of particulate emissions, as it was reported that 31 diesel vehicles whose age averaged 22 years showed average emissions of 944 mg/km, with one vehicle emitting at a rate of 10,500 mg/km. For comparison, emission rates of total particles were below 6 mg/km for most production catalyst vehicles. The black crusts from the cathedral of Seville, and also those studied in other different European monuments (Fobe et al., 1995; Hermosin et al., 2004), contain molecular markers that are characteristic of petroleum derivatives and generated by the traffic. In fact, a strong correspondence between the lipids present in urban aerosols and those of cathedral black crusts was found, thus confirming
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RT Fig. 4. Hopanes identified in aerosols sampled under partial restricted traffic conditions (sampling B) and cathedral black crusts (sample D). Hopanes (trace not shown) were absent in aerosols collected under no traffic regime (sampling C). Identification of peaks in the text.
the strong impact of traffic on black crust formation and on the deterioration of monuments. Diesel soot has a considerable influence in the composition of the atmosphere of Seville and, subsequently, in the blackening of urban monuments, which is of particular concern in Mediterranean countries where an aging fleet composed of old diesel engines are used for public transport and freight. The compositional changes of aerosols through the year, and particularly in periods of traffic restriction, corroborate this assertion. Acknowledgements This work was supported by the European Commission, Project EVK4-CT2000-00029 (CARA-
MEL), and the former Spanish Ministry of Science and Technology, now Ministry of Education and Science, project BTE2001-1277. Guest Associate Editors—F.J. Gonzalez-Vila and J.A. Gonzalez-Perez References Cachier, H., Sarda-Este`ve, R., Oikonomou, K., Sciare, J., Bonazza, A., Sabbioni, C., Greco, M., Reyes, J., Hermosin, B., SaizJimenez, C., 2004. Aerosol characterization and sources in different European urban atmospheres: Paris, Seville, Florence and Milan. In: Saiz-Jimenez, C. (Ed.), Air Pollution and Cultural Heritage. Balkema Publishing, Leiden, pp. 3–14. Cass, G.R., 1998. Organic molecular tracers for particulate air pollution sources. Trends in Analytical Chemistry 17, 356–366.
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025 Fobe, B.O., Vleugels, G.J., Roekens, E.J., van Grieken, R.E., Hermosin, B., Ortega-Calvo, J.J., Sanchez del Junco, A., SaizJimenez, C., 1995. Organic and inorganic compounds in limestone weathering crusts from cathedrals in southern and western Europe. Environmental Science and Technology 29, 1691–1701. Fraser, M.P., Cass, G.R., Simoneit, B.R.T., 1999. Particulate organic compounds emitted from motor vehicle exhaust and in the urban atmosphere. Atmospheric Environment 33, 2715–2724. Gavin˜o, M., Hermosin, H., Verges-Belmin, V., Nowik, W., SaizJimenez, C., 2004. The black crust composition from Saint Denis Basilica, France, as revealed by gas chromatography– mass spectrometry. Journal of Separation Science 27, 513– 523. Grimalt, J.O., Rosell, A., Simo, R., Saiz-Jimenez, C., Albaiges, J., 1991. A source correlation study between the organic components present in the urban atmosphere and in gypsum crusts from old building surfaces. In: Manning, D.A.C. (Ed.), Organic Geochemistry. Advances and Applications in the Natural Environment. Manchester University Press, Manchester, pp. 513–515. Hermosin, B., Gavin˜o, M., Saiz-Jimenez, C., 2004. Organic compounds in black crusts from different European monuments: a comparative study. In: Saiz-Jimenez, C. (Ed.), Air Pollution and Cultural Heritage. Balkema Publishing, Leiden, pp. 47–55. Philp, R.P., 1985. Biological markers in fossil fuel production. Mass Spectrometry Reviews 4, 1–54. Sagebiel, J.C., Zielinska, B., Walsh, P.A., Chow, J.C., Cadle, S.H., Mulawa, P.A., Knapp, K.T., Zweidinger, R.B., Snow, R., 1997. PM-10 exhaust samples collected during IM-240
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dynamometer test on in-service vehicles in Nevada. Environmental Science and Technology 31, 75–83. Saiz-Jimenez, C., 1993. Deposition of airborne organic pollutants on historic buildings. Atmospheric Environment 27B, 77–85. Saiz-Jimenez, C., 2003. Organic pollutants in the built environment and their effect on the microorganisms. In: Brimblecombe, P. (Ed.), The Effect of Air Pollution on the Built Environment. Imperial College Press., London, pp. 183–225. Saiz-Jimenez, C., Bernier, F., 1981. Gypsum crust on building stones. A scanning electron microscopy study. Sixth Triennial Meeting ICOM, Committee for Conservation, Paper 81/10/5, 9 p. Saiz-Jimenez, C., Garcia del Cura, M.A., 1991. Sulfated crusts: a microscopic, inorganic and organic analysis. In: Baer, N.S., Sabbioni, C., Sors, A.I. (Eds.), Science. Technology and European Cultural Heritage. C.E.C.-Butterworth-Heinemann, Oxford, pp. 527–530. Saiz-Jimenez, C., Brimblecombe, P., Camuffo, D., Lefe`vre, R.A., Van Grieken, R., 2004. Damages caused to European monuments by air pollution: assessment and preventive measures. In: Saiz-Jimenez, C. (Ed.), Air Pollution and Cultural Heritage. Balkema Publishing, Leiden, pp. 91–109. Simoneit, B.R.T., 1985. Application of molecular marker analysis to vehicular exhaust for source reconciliations. International Journal of Environmental Analytical Chemistry 22, 203–233. Simoneit, B.R.T., 1986. Characterization of organic constituents in aerosols in relation to their origin and transport: a review. International Journal of Environmental Analytical Chemistry 23, 207–237. Simoneit, B.R.T., Mazurek, M.A., 1981. Air pollution: the organic components. CRC Critical Reviews in Environmental Control 11, 219–276.
Organic composition of Seville aerosols J. Reyes, B. Hermosin, C. Saiz-Jimenez
*
Instituto de Recursos Naturales y Agrobiologia, CSIC, Apartado 1052, 41080 Sevilla, Spain Available online 12 October 2006
Abstract The organic species present in the aerosols of the Seville atmosphere, sampled at different periods of the year, under distinct traffic regimes, are presented. The compounds are related to incomplete fuel combustion in vehicular exhausts. 2006 Elsevier Ltd. All rights reserved.
1. Introduction Urban air pollution is a major concern throughout Europe as industrial wastes, traffic congestion and over-crowding in cities create pollutants that significantly contribute to environmental damage and health problems. Urban aerosols generally consist of a mixture of lipid materials emitted locally along with the aged material that has been carried into the urban area by winds. Urban atmospheric environments contain many organic pollutants which are related to incomplete fuel combustion in domestic heating, industrial plants and vehicular exhausts, such as long-chain alkanes, monocarboxylic and dicarboxylic acids, polycyclic aromatic hydrocarbons (PAH), and terpenoids (Simoneit and Mazurek, 1981). In addition to organic compounds, carbonaceous matter (mainly elemental carbon) is common in urban environments. Buildings and monuments act as repositories of these airborne organic pollutants, which are entrapped at the stone surfaces as part of the developing black crusts. *
Corresponding author. E-mail address: [email protected] (C. Saiz-Jimenez).
Traffic congestion and air pollution are a major problem in the city of Seville with a historic centre with very narrow streets. For more than five decades, exhaust emissions from gasolineand diesel-powered vehicles contributed to the deterioration of the cathedral of Seville through the formation of black crusts (Saiz-Jimenez, 1993), a phenomenon that has also been described in other European cathedrals (Hermosin et al., 2004). In the last 25 years several reports on this topic and exhaustive analyses of deteriorated building materials from the cathedral of Seville were presented (Saiz-Jimenez and Bernier, 1981; Saiz-Jimenez and Garcia del Cura, 1991; Fobe et al., 1995). However, the characterization of the organic components of the aerosols, and its comparison with the organic fractions extracted from the black crusts formed on the building surfaces is far from complete (Grimalt et al., 1991). In this paper, we report on the organic compounds present in aerosols collected in a station located in the cathedral of Seville, at different periods and traffic regimes. These compounds are compared with those deposited on the stone surface of the same monument.
0146-6380/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.orggeochem.2006.08.006
2020
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025
2. Materials and methods 2.1. Sample collection Aerosols were collected in a high volume air sampler (Staplex Co., New York, USA, model TFIA-2) operating at a flow rate of 2 m3/min. The sampler was installed in the roof of the Assumption portal, cathedral of Seville, at about 20 m height, and facing the traffic-congested Constitution Avenue. Different traffic regimes were considered: Sampling A, in regular traffic conditions: from 11 to 14 June 2002 from 9.00 to 20.00. Vehicular traffic included buses, cars and mopeds. Sampling B, under partially restricted traffic conditions: from 24 to 30 March 2002, from 9.00 to 17.00. Vehicular traffic permitted only for cars and mopeds during the morning. Sampling C, under no traffic: from 24 to 30 March 2002. Sampling was carried out from 17.00 to 2.00, except for 29 March in which sampling continued from 2.00 to 8.00. No vehicular traffic, but continuous religious processions carrying thousands of candles occupied the street. Black crusts were collected from the Baptism portal during the cleaning and restoration works carried out in 2000 (sample D). This portal is at some 35 m from sampling station. The sampling area was located at 20 m height.
using a 30 m · 0.25 mm TRB-5HT column (film thickness 0.1 lm). The GC oven was programmed from 80 to 120 C at 30 C/min and then to 320 C. The final temperature was held for 20 min. In the analytical procedure followed in this work, the carboxylic acids were recovered as the corresponding methyl esters, and the hydroxyls as methoxyls. Throughout this paper they are referred to as acids and hydroxyls – their original forms – rather than as derivatized methyl esters and methoxyls. The compounds were identified by comparison of their mass spectra with a self-compiled data bank of compounds from a variety of samples (Saiz-Jimenez, 1993, 2003; Gavin˜o et al., 2004). In some cases, identification was achieved by computer analysis from a National Bureau of Standards library of about 107,886 spectra, with the computer matching being checked against standards whenever possible. 3. Results and discussion Great concentrations of gases and aerosols are reached in Constitution Avenue, a very narrow street delimited by the western fac¸ade of the cathedral of Seville (Fig. 1). This street routes all traffic to the city centre. A 1997 study estimated average daily traffic as 2200 buses, 7000 motorcycles and 13,600 cars (Saiz-Jimenez et al., 2004). Nowadays the figures could likely be higher. However, every
2.2. Analysis of compounds The analytical procedure for identification of compounds present in aerosols and black crusts was as follows. The bulk samples collected on the air filter were extracted in a Soxhlet apparatus with dichloromethane-methanol (2:1) for 72 h. The extracts were evaporated under vacuum at low temperature (below 40 C) and redissolved in dichloromethane-methanol (2:1). The resulting extract was fractionated using a silica column, eluted with hexane (fraction I), hexane-dichloromethane (1:1) (fraction II), dichloromethane (fraction III), and finally with methanol (fraction IV). Compounds present in fractions III and IV were methylated with trimethylsilyldiazomethane (TMSCHN2). In this paper, we will report on the study of fraction I containing the most characteristic series of compounds and molecular markers. For analysis, 2 ll of each fraction were injected in a Fisons gas chromatography–mass spectrometry (GC–MS) instrument, model GC 8000/MD 800,
Fig. 1. Constitution Avenue, a narrow street delimited by the western fac¸ade of the cathedral of Seville.
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025
year, during a few weeks near Holy Week, the Sevillian municipality introduces traffic regulations resulting in partial or total closure of the street to permit religious processions. A study of the chemical composition of aerosols sampled at different periods of the year under distinct traffic regimes is, therefore, possible. The inorganic data obtained in that sampling were reported by Cachier et al. (2004) who found that elemental carbon (EC) in Seville aerosols (sampling in the same station used in this study) was three times higher than in Florence cathedral and twice that in Paris (Saint Eustache church) or Milan cathedral. This was explained by the fact that Seville is heavily influenced by heavy-duty diesel buses which are known to produce predominantly fine EC particles. A preliminary sampling tour around the cathedral of Seville while recording particle number with a portable condensation nuclei counter showed that the background level was about 20,000 particles/ cm3 (Fig. 2). However, Constitution Avenue revealed concentrations as high as 329,000 particles/cm3. The high values corresponded to diesel bus routes on the street. This experiment illustrates the heavy air pollution and the deleterious effect of traffic channelling in the narrow Constitution Avenue, which enhances particulate pollution (Cachier et al., 2004).
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After sampling with the high volume air sampler, the filters were extracted with solvents and the total extracts analysed by GC–MS. The total ion current chromatogram traces (not shown) confirmed that the extracts contained a complex mixture of compounds dominated by n-fatty acids (C12–C18), aliphatic dicarboxylic acids (C8, C9), aromatic compounds (benzenecarboxylic acids) and nicotine. In addition, the series of n-alkanes (C13–C29) was evident. Many other compounds present in minor or trace amounts could be discerned. A further fractionation was necessary in order to separate specific series of compounds for source apportionments and to avoid overlapping and/or complex unresolved mixtures. Although four different fractions were obtained from the total extracts by column chromatography, here we will refer only to fraction I, which has significant diagnostic interest (e.g., biomarkers). Fig. 3 shows a selected ion mass chromatogram (m/z 85) for fraction I, indicating the distribution of n-alkanes in sampling A (no traffic restrictions), B (partial traffic restrictions) and C (no traffic). The traces are dominated (in decreasing order) by a large unresolved complex mixture (UCM) or ‘‘hump’’, with the main resolved components being n-alkanes. Isoprenoid hydrocarbons (pristane and phytane) were identified as well. While a similar
Fig. 2. Particle density around the cathedral. Bar denotes the Constitution Avenue transect. Higher peaks correspond to the transit of buses.
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A
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RT Fig. 3. Ion mass chromatogram (m/z 85) of aerosols sampled at different traffic regimes (A–C) and cathedral black crusts (D). Numbers indicate carbon atoms of the corresponding n-alkane. P is pristane and F phytane.
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025
n-alkane distribution was observed in all the three chromatograms, differences in maximum at C29 for A, and at C27 for B and C, and in the intensity of the UCM formed by the presence of many overlapping peaks were evident. Similar patterns of n-alkanes maximising at C29 were reported for urban areas in Western United States aerosols (Simoneit, 1986). Fig. 3D shows the ion mass chromatogram trace (m/z 85) for fraction I obtained from black crusts collected from the Baptism portal. There, a bimodal distribution of n-alkanes was observed. The first part maximized at n-C21, and the second part of the series had a maximum at n-C29. Patterns of n-alkanes maximising at C21 were reported for diesel and gasoline engine exhausts and patterns maximising at C29 were typical of urban aerosols (Simoneit, 1985). Lubricating oil used in Sevillian buses showed a pattern maximising at C30 but diesel soot from the same buses presented a maximum at C20 (data not shown). The pronounced unresolved naphthenic hump in the aerosols obtained with no traffic restriction (A) was similar to that obtained from lubricating oils. These data indicated that n-alkanes present in black crusts seems to have a double imprint, from aerosols originated from uncombusted petroleum derivatives (gasoline, diesel) whereas the naphthenic hump with associated triterpenoid markers (see below) originated from lubricating oils. Other series of compounds found in fraction I of aerosol extracts and black crusts, such as alkylcyclohexanes, alkylbenzenes and alkylnaphthalenes will not be discussed here, as they are not source-specific, and are generally found in every combustion emission. Hopanes are molecular fossils present in crude petroleum. They have been used to trace the sources or identify the origin of petroleum derivatives. Simoneit (1985) proposed that hopanes could be used as tracers for motor vehicle exhaust particles in the atmosphere. Hopanes are present in the lubricating oil used by both gasoline- and diesel-powered motor vehicles (Cass, 1998) and have been reported to be common components of aerosols and black crusts (Saiz-Jimenez, 1993, 2003). Hopanes (Fig. 4) also eluted in fraction I of the aerosol extracts. These biomarkers were relatively easy to detect using ion monitoring at m/z 191, in spite of their low contributions to the fraction. The hopanes identified in the aerosols were 18a(H)22,29,30-trisnorhopane (1), 17a(H)-22,29,30-trisnorhopane (2), 17a(H),21b(H)-30-norhopane (3),
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17a(H),21b(H)-hopane (4), 17a(H),21b(H)-homohopane 22S (5), 17a(H),21b(H)-homohopane 22R (6), 17a(H),21b(H)-bishomohopane 22S (7), 17a(H), 21b(H)-bishomohopane 22R (8), 17a(H),21b(H)-trishomo hopane 22S (9), 17a(H),21b(H)-trishomohopane 22R (10), 17a(H),21b(H)-tetrakishomohopane 22S (11), 17a(H),21b(H)-tetrakishomohopane 22R (12), 17a(H),21b(H)-pentakishomohopane 22S (13), and 17a(H),21b(H)-pentakishomohopane 22R (14). This pattern of hopanes was similar to those reported for aerosol particles (Simoneit, 1985), crude oil (Philp, 1985), automobile and diesel engine exhausts (Fraser et al., 1999) and black crusts (Saiz-Jimenez, 1993, 2003). The presence of minor amounts of the isoprenoid hydrocarbons pristane and phytane and the hopanes indicates a petroleum source for these compounds. Interestingly, hopanes were not detected in fraction I of aerosols obtained when there was no traffic in the area (C) which clearly confirms that this series of compounds was emitted by motor vehicles. Grimalt et al. (1991) reported the close similarity between the organic composition of black crusts from the Holy Family church in Barcelona, Spain, and airborne particulates, collected by glass fibre filtration, and gas-phase organic compounds, obtained by polyurethane foam adsorption. These facts and the finding of carbonaceous particles entrapped in the voids of gypsum crystals (SaizJimenez and Bernier, 1981) demonstrated that the organic compounds present in the black crusts, covering the building stones in urban environments, are the result of a direct input of air pollutants, the buildings acting as non-selective surfaces passively entrapping all deposited aerosols and particulate matter, from whose analysis a source can be traced. A study of Sagebiel et al. (1997) illustrated the importance of diesel vehicles in the production of particulate emissions, as it was reported that 31 diesel vehicles whose age averaged 22 years showed average emissions of 944 mg/km, with one vehicle emitting at a rate of 10,500 mg/km. For comparison, emission rates of total particles were below 6 mg/km for most production catalyst vehicles. The black crusts from the cathedral of Seville, and also those studied in other different European monuments (Fobe et al., 1995; Hermosin et al., 2004), contain molecular markers that are characteristic of petroleum derivatives and generated by the traffic. In fact, a strong correspondence between the lipids present in urban aerosols and those of cathedral black crusts was found, thus confirming
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J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025 3
B 4 7
5 6 2
1
9
8
10 11
13 12
14
3
D
4
5 6 1
7 13
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8
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RT Fig. 4. Hopanes identified in aerosols sampled under partial restricted traffic conditions (sampling B) and cathedral black crusts (sample D). Hopanes (trace not shown) were absent in aerosols collected under no traffic regime (sampling C). Identification of peaks in the text.
the strong impact of traffic on black crust formation and on the deterioration of monuments. Diesel soot has a considerable influence in the composition of the atmosphere of Seville and, subsequently, in the blackening of urban monuments, which is of particular concern in Mediterranean countries where an aging fleet composed of old diesel engines are used for public transport and freight. The compositional changes of aerosols through the year, and particularly in periods of traffic restriction, corroborate this assertion. Acknowledgements This work was supported by the European Commission, Project EVK4-CT2000-00029 (CARA-
MEL), and the former Spanish Ministry of Science and Technology, now Ministry of Education and Science, project BTE2001-1277. Guest Associate Editors—F.J. Gonzalez-Vila and J.A. Gonzalez-Perez References Cachier, H., Sarda-Este`ve, R., Oikonomou, K., Sciare, J., Bonazza, A., Sabbioni, C., Greco, M., Reyes, J., Hermosin, B., SaizJimenez, C., 2004. Aerosol characterization and sources in different European urban atmospheres: Paris, Seville, Florence and Milan. In: Saiz-Jimenez, C. (Ed.), Air Pollution and Cultural Heritage. Balkema Publishing, Leiden, pp. 3–14. Cass, G.R., 1998. Organic molecular tracers for particulate air pollution sources. Trends in Analytical Chemistry 17, 356–366.
J. Reyes et al. / Organic Geochemistry 37 (2006) 2019–2025 Fobe, B.O., Vleugels, G.J., Roekens, E.J., van Grieken, R.E., Hermosin, B., Ortega-Calvo, J.J., Sanchez del Junco, A., SaizJimenez, C., 1995. Organic and inorganic compounds in limestone weathering crusts from cathedrals in southern and western Europe. Environmental Science and Technology 29, 1691–1701. Fraser, M.P., Cass, G.R., Simoneit, B.R.T., 1999. Particulate organic compounds emitted from motor vehicle exhaust and in the urban atmosphere. Atmospheric Environment 33, 2715–2724. Gavin˜o, M., Hermosin, H., Verges-Belmin, V., Nowik, W., SaizJimenez, C., 2004. The black crust composition from Saint Denis Basilica, France, as revealed by gas chromatography– mass spectrometry. Journal of Separation Science 27, 513– 523. Grimalt, J.O., Rosell, A., Simo, R., Saiz-Jimenez, C., Albaiges, J., 1991. A source correlation study between the organic components present in the urban atmosphere and in gypsum crusts from old building surfaces. In: Manning, D.A.C. (Ed.), Organic Geochemistry. Advances and Applications in the Natural Environment. Manchester University Press, Manchester, pp. 513–515. Hermosin, B., Gavin˜o, M., Saiz-Jimenez, C., 2004. Organic compounds in black crusts from different European monuments: a comparative study. In: Saiz-Jimenez, C. (Ed.), Air Pollution and Cultural Heritage. Balkema Publishing, Leiden, pp. 47–55. Philp, R.P., 1985. Biological markers in fossil fuel production. Mass Spectrometry Reviews 4, 1–54. Sagebiel, J.C., Zielinska, B., Walsh, P.A., Chow, J.C., Cadle, S.H., Mulawa, P.A., Knapp, K.T., Zweidinger, R.B., Snow, R., 1997. PM-10 exhaust samples collected during IM-240
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dynamometer test on in-service vehicles in Nevada. Environmental Science and Technology 31, 75–83. Saiz-Jimenez, C., 1993. Deposition of airborne organic pollutants on historic buildings. Atmospheric Environment 27B, 77–85. Saiz-Jimenez, C., 2003. Organic pollutants in the built environment and their effect on the microorganisms. In: Brimblecombe, P. (Ed.), The Effect of Air Pollution on the Built Environment. Imperial College Press., London, pp. 183–225. Saiz-Jimenez, C., Bernier, F., 1981. Gypsum crust on building stones. A scanning electron microscopy study. Sixth Triennial Meeting ICOM, Committee for Conservation, Paper 81/10/5, 9 p. Saiz-Jimenez, C., Garcia del Cura, M.A., 1991. Sulfated crusts: a microscopic, inorganic and organic analysis. In: Baer, N.S., Sabbioni, C., Sors, A.I. (Eds.), Science. Technology and European Cultural Heritage. C.E.C.-Butterworth-Heinemann, Oxford, pp. 527–530. Saiz-Jimenez, C., Brimblecombe, P., Camuffo, D., Lefe`vre, R.A., Van Grieken, R., 2004. Damages caused to European monuments by air pollution: assessment and preventive measures. In: Saiz-Jimenez, C. (Ed.), Air Pollution and Cultural Heritage. Balkema Publishing, Leiden, pp. 91–109. Simoneit, B.R.T., 1985. Application of molecular marker analysis to vehicular exhaust for source reconciliations. International Journal of Environmental Analytical Chemistry 22, 203–233. Simoneit, B.R.T., 1986. Characterization of organic constituents in aerosols in relation to their origin and transport: a review. International Journal of Environmental Analytical Chemistry 23, 207–237. Simoneit, B.R.T., Mazurek, M.A., 1981. Air pollution: the organic components. CRC Critical Reviews in Environmental Control 11, 219–276.