Environ. Sci. Technol. 2001, 35, 306-311
Organic Aerosols in Urban and Waste Landfill of Algiers Metropolitan Area: Occurrence and Sources NOUREDDINE YASSAA Laboratoire d’Analyse Organique Fonctionnelle, Institut de Chimie, U.S.T.H.B., BP 32, El-Alia, Bab-Ezzouar, Algiers, Algeria BRAHIM YOUCEF MEKLATI* Centre de Recherche Scientifique et Technique en Analyses Physico-Chimiques (C.R.A.P.C), BP 248, Alger RP, 16004, Algiers, Algeria ANGELO CECINATO* AND FABIO MARINO Istituto sull’Inquinamento Atmosferico del C.N.R., Area della Ricerca di Roma, Via Salaria Km 29.300, C.P.10, 00016, Monterotondo Scalo RM, Italy
In both downtown Algiers and the waste landfill of Oued Smar, the concentrations of particulate organic compounds comprising n-alkanes, n-alkanoic acids, n-alkan-2-ones, polycyclic aromatic hydrocarbons (PAHs), oxygenated (OPAHs), and nitrated polycyclic aromatic hydrocarbons (NPAHs) in ambient air were measured from May 1998 to February 1999. All the components except OPAHs had a tendency to strongly increase in colder weather. Motor vehicles were found to be the main source of airborne particles in downtown Algiers, while the combustion and pyrolysis processes and bacterial activity seemed to concur to the air pollution at the Oued Smar waste landfill. The biogenic emission, which was restricted to the lighter fraction of the n-alkanes and n-alkanoic acids, appeared to contribute at a lesser extent. The in-situ generation of some OPAHs and NPAHs seemed to contribute to air pollution, especially during the summertime. As expected, the ambient concentrations of NPAHs and OPAHs were lower than those of their parent PAHs. The seasonal variations in ambient NPAH and OPAH concentrations are due partly to fluctuations of precursors including NOx, O3, and OH radicals. In general, the wintertime concentrations of the organic pollutants in Algiers were similar to those measured in Europe and especially over the Mediterranean Basin. Further investigations have been planned in order to obtain a thorough knowledge of the air pollution as well as the organic content of materials burning at the Oued Smar waste landfill. In particular, our concern will be addressed to sources of toxic components, to formulate strategies suitable for reducing health risk for the populations living in the region of Algiers.
Introduction Air pollution related to aerosols has recently been a concern of scientists and Public Agencies since an increased health * Corresponding authors phone: (213)02-247406 (B.Y.M.) or (39)06-90672265 (A.C.); fax: (213)02-247406 (B.Y.M.) or (39) 06-90672660 (A.C.); e-mail:
[email protected] (A.C.). 306
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risk for humans has been proven to arise from exposure to fine particles in general and specifically to their organic components. In that perspective, a key role is played by polycyclic aromatic hydrocarbons (PAHs), a class of ubiquitous contaminants, some of which have strong mutagenic and carcinogenic potencies. PAHs are byproducts from the incomplete combustion or pyrolysis of any organic material. House heating, coke and energy production, waste incineration, and motor vehicles are the major sources of PAHs existing in the atmosphere. Also PAH derivatives containing oxygen or nitro groups (OPAHs and NPAHs, respectively) have been recognized as powerful mutagens and carcinogens (1-3). They are among the main components of soot emitted from diesel and gasoline engines (4). OPAHs and NPAHs are present also in atmospheric aerosols, overall adsorbed onto the particle surface. They are formed during the combustion of fossil fuels as well as the decomposition of parent hydrocarbons induced by oxidants, which occur in ambient air (2, 5-11). Although n-alkanes and n-alkanoic acids present in the aerosols are originated by both anthropic and natural sources, nevertheless the input due to vegetation can be recognized through the congeners distribution among the respective class. In fact, an odd-to-even carbon number preference was observed for alkanes peaking in the C27-C31 range, while the contrary was found peculiar of acids (12). Concurrent production and sink behaviors of any atmospheric component leads organic particles to affect the whole environment and to allow that contaminant to reach vegetables and other foodstuffs (13). Until today, investigations dealing with the presence of organic microcomponents of aerosols in the Mediterranean Basin were restricted solely to the northern coasts and to developed countries (10, 14), while any reliable inventory of POM sources fails yet in emerging countries, in particular those of the African coasts. Algeria is located in the North of Africa and looks on the Mediterranean Sea along its big coast; finally, its domain is 1200 km broad. During the last two decades, the metropolitan agglomeration of Algiers has experienced a big increase of motor vehicles, which caused a dramatic worsening of the air quality and related effects (e.g., high levels of gas mixtures and fine aerosols affecting visibility, human health, material damage, etc.). Besides that, not far from the city of Algiers lies the open-air municipal landfill of Oued Smar, which is not yet subjected to any control from Public Authorities. Therefore, uncontrolled accumulation of wastes, degradation, and exhausts of refuses coming from private houses, industries, and hospitals concur to a global budget of pollution, affecting the air quality on both a local and a regional scale. In fact, dirty fogs are often observed, which envelop the Algiers region. These events occur mainly during the night or at sunrise, whenever the meteorological stability is well-developed (concurrently with sweet winds blowing and strong thermal inversion dominating the area). This situation is very usual, and inhabitants and workers exposed to Algiers pollution experience increased adverse effects, in particular respiratory difficulties, irritation of eyes, and gorge. Children, the elderly, and the sick suffer the main vulnerability to air pollution. To determine levels of pollution in the city of Algiers and also to highlight the different content of the organic aerosols between downtown and the Oued Smar landfill, we carried out a monitoring campaign from May 1998 to February 1999. The composition of PAH, OPAH, NPAH, n-alkane, linear alkyl monocarboxylic acid, and ketone fractions was investigated 10.1021/es991316d CCC: $20.00
2001 American Chemical Society Published on Web 12/13/2000
FIGURE 1. General view of Algiers Bay and detailed position of the two sampling sites investigated in the city of Algiers. and tentatively related to the sources of pollution.
Experimental Section Sampling Sites. Figure 1 provides the general view of Algiers Bay as well as a detailed siting of both the locations investigated. Aerosols were collected in downtown Algiers, where the motor vehicle exhaust was recognized as the main source of both NOx, volatile organic compounds (15-17), and black carbon. The global budget of pollutants is enough high to depress the quality of life of living things (humans and biota). In that respect, it is worth noting that about 560 000 motor vehicles circulate everyday in Algiers, with 71% of them 10 years old or more. All of them require dirty fuels such as leaded gasoline and petrol oil. For our experiment inside the city, we sampled atmospheric aerosols at about 200 m from the sea, 5 m from a road with rushing traffic, and about 3 m from ground level. The Oued Smar Municipal Landfill was chosen as subject of our investigation because it is the largest one existing in Algeria. It is located at about 13 km from downtown Algiers, east of the city and also in the west part of the same industrial zone; it covers a surface of about 37.5 ha. The landfill represents an important emission source for a number of atmospheric pollutants comprising gaseous species compounds (volatile organics, SO2, NOx, CO, NH3) as well as solids (dusts, ashes, soot). According to a recent estimation (18), 4000 ton/day of wastes is usually stored there. House wastes account for 1600 ton/day, and the industrial ones, including toxic or dangerous substances, account for the remaining (18). All refuses are burnt in open air; neither combustion parameters nor the release of exhaust are subject to any control. Within our investigation, aerosol samples were collected about 50 m from the municipal waste landfill and at 2 m above the ground. Sampling and Analysis of Aerosols. Aerosols were collected by means of a medium-volume sampling apparatus (16 L/min) provided with a size-selective inlet suitable to enrich from air only particles smaller than 10 µm and a counter measuring the air volume passed through the particle filter over the sampling period. The particles were enriched from air onto a PTFE inert membrane (Teflo R2PL047-type; provided by Gelman Scientific, Ann Arbor, MI; 47 mm o.d., 1 mm pore size), and then filters were wrapped in aluminum foil and stored at 4 °C until subjected to chemical determinations (19, 20). Each sampling started at 7.00 a.m. and lasted 24 h. The soluble organic fraction of aerosols was extracted from enriched filters by refluxing a dichloromethane-acetone mixture (DCM-ACE, 3:1 v/v, 40 mL) in a mini-Soxhlet
FIGURE 2. Flowchart of analytical procedures for the particulate organic matter (POM) determination. apparatus for 16 h. Solvents were evaporated using a gentle flow of N2 at room temperature, and then the extract was fractionated by following the procedure outlined in Figure 2. Briefly (10), the organic extract was first dissolved in a toluene solution containing known concentrations of internal standards suitable for determining n-alkanes, NPAHs and PAHs, i.e., (i) 1-bromotetradecane and 1-bromoeicosane, (ii) perdeuterated 1-nitropyrene (1-NPY-d9), and (iii) o-terphenyl (OTP) and m-triphenylbenzene (TPB), respectively. An aliquot of each sample extract (4/5th of the total) was eluted through a neutral alumina column in order to separate nonpolar aliphatic species from the bulk of polycyclic aromatic hydrocarbons and polar compounds. Two fractions were collected by eluting the extract with n-hexane (n-C6) and DCM in sequence. The second eluate was further separated by normal-phase HPLC in three subfractions containing the following: (i) PAHs, (ii) NPAHs, and (iii) OPAHs with ketones, respectively. The rest of sample (1/5th of the total) was directly subjected to esterification to determine its acid content. In this respect, a mixture of methanol and boron trifluoride in excess of methanol (BF3) was added to the dry residue, and the solution was held at 60 °C for 15 min; then the solvent was evaporated. The esterified carboxylic acids and the other organic compounds were back-dissolved with DCM and purified by chromatography through a neutral alumina column; for this purpose, a former elution with n-hexane cut off nonpolar aliphatics, whereas DCM allowed the recovery of methyl derivatives of acids at almost 100% extent. n-Alkanes were determined by gas chromatography coupled with flame ionization detection using a 30 m long DB-5 type capillary column (0.32 mm id, 0.3 µm film thickness, supplied by J&W, Folsom, CA) connected to a Mega-5160 gas chromatograph (provided by Fisons Instruments, Milan, Italy) and equipped with a cold-on-column injection system. The esterified acids, ketones, PAH, and PAH derivatives were determined by a HP 5890 gas chromatography coupled with a HP 5970 B mass spectrometric detection operated in SIM mode (Hewlett-Packard Instruments, Palo Alto, CA). The separation was achieved by means of a 25 m long capillary column coated with a HP-5 type methylphenyl silicone phase (Hewlett-Packard, 0.2 mm id, 0.33 µm film VOL. 35, NO. 2, 2001 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 1. Seasonal Mean n-Alkane Concentrations (ng m-3) and the CPI Values in Downtown Algiers and Oued Smar Landfill, 1998-1999 downtown Algiers compd C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 total CPI
Oued Smar landfill
summer
winter
summer
winter
0.1 0.5 2.5 1.6 2.9 5.7 8.6 9.5 7.3 4.4 2.8 3.1 1.2 3.4 0.5 0.8
5.0 14.9 12.2 9.8 10.9 7.5 8.9 5.2 5.8 3.9 2.7 2.7 1.9 1.4 0.8 0.6
0.2 0.7 8.3 2.2 4.2 9.0 12.3 13.4 10.0 6.7 4.7 3.3 3.0 1.8 1.0 0.7
20.6 73.0 41.2 45.8 48.4 29.4 26.7 20.8 26.8 18.9 11.2 15.0 9.9 6.9 3.9 3.0
55 2.0
94 1.2
82 1.0
401 1.3
thick). A temperature program from 80 to 280 °C was adopted. PAH were identified by recording molecular ion traces and fragments and isotopic and doubly charged ions ([M]+, [M - 1]+, [M + 1]+, and [M/2]+, respectively). Molecular [247]+ and four characteristic fragment ions (i.e., [217]+, [201]+, [200]+, and [189]+) were selected for detecting nitrated fluoranthenes and pyrenes. OPAHs were determined by detecting their spectral pattern, while [M]+, [74]+, [143]+, and [227]+ traces were selected for methylated acids. The [58]+ ion current was used in order to quantify ketones. All internal standards were identified by molecular ions. All internal and authentic standards were supplied by Aldrich Chemical Co. (Milwaukee, WI), except NPAHs and 1-NPy-d9, which were synthesized starting from the parent PAHs or obtained through purification from emission samples; the procedures adopted for these latter are described elsewhere (21). The whole procedure was tested previously by repeating both the extraction, cleanup, and gas chromatographic analysis on aerosols as well as by analyzing pairs of samples collected in parallel at our institute. Recoveries not larger than 10% were found at the second (replicated) extraction, whereas a reproducibility over 80% was obtained when parallel samples were investigated; only n-alkanes showed larger variabilities of the analytical results. In all cases, the use of internal standards allowed us to account for the most of losses due to volatilization of light compounds.
Results and Discussion Since the meteorological situation in spring and autumn is quite unstable over the Algiers region, we were forced to limit our investigation to summer and winter periods. n-Alkanes. Table 1 reports the mean concentrations of n-alkanes belonging to the C16-C31 range, which we recorded during the cold and warm seasons. The carbon preference index (CPI) was also calculated for each sample by using the following formula:
CPI ) 1/2 × [(C24 + C26 + C28 + C30)/(C25 + C27 + C29 + C31) + (C26 + C28 + C30 + C32)/(C25 + C27 + C29 + C31)] The total content of n-alkanes ranged from 55 to 188 ng m-3 in downtown Algiers and from 82 to 602 ng m-3 at Oued Smar (monthly means). A dramatic increase was observed 308
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during the winter period (i.e., up to 5× at the landfill). At downtown site, the biggest concentrations were reached by n-C24 in the summer (9.5 ng m-3) and by n-C17 in the winter (14.9 ng m-3), while at Oued Smar the predominant congener was n-C23 in the summer and n-C17 in the winter (13.4 and 73.0 ng m-3, respectively). Among n-alkanes, the maximum concentrations in the air were in all cases shifted toward low carbon numbers. That seemed to indicate that petrogenic or microbial sources are responsible for the presence of hydrocarbons into the atmosphere, whereas a big contribution of high plants (which should lead to predominance of n-C27-n-C33 congeners) could be excluded. The n-alkane pattern observed in downtown Algiers during both warm and cold seasons was similar to that of motor vehicular exhaust, allowing us to identify the main source of carbon particles there. In contrast, CPI values in Algiers were close to 2 in summer and 1 in winter. CPI has been described in the literature as a chemical index suitable for assessing the plant wax contribution versus fossil fuel (22) to aliphatic contents in aerosols; in fact, a CPI equal to 1 is indicative of the burning of mineral oil, whereas high figures (up to 7) highlight plant wax release. A slight predominance of odd-numbered alkanes above C25 was only observed in downtown Algiers in the summer. This should be explained by a small input coming from small vascular plant emission. Particulate plant waxes are usually generated by volatilization-condensation processes (14), strongly depending on temperature. By contrast, the traffic circulation seems to determine the seasonal trends of n-alkane concentrations concurrently with the evolution of the climatic situation. For instance, a strong temperature inversion in the boundary layer frequently appears in winter preventing the dispersion of pollutants (23); this phenomenon is likely to accumulate n-alkanes over the land. In contrast, a large portion of Algiers population moves away from the city for holidays during the summer. Stocking and burning of several kinds of materials including biomass and refuses (i.e., plants, foodstuffs, animals, and plastics) caused the huge presence of n-alkanes in the aerosols at the Oued Smar site. The CPI was close to 1 over the entire year there. The air contamination consequence from anthropic activities appeared more severe at Oued Smar than in downtown Algiers. At the landfill, the dropping of n-alkanes in air during the summer was probably due to the strong reduction in the amount of wastes burnt. In fact, the turn off occurs by local industries, which are responsible of over 50% of the whole waste budget. At that time, the existence of organic aerosols might be attributed to the domestic wastes. We could not further investigate the true composition of the n-alkane fraction in the emission of municipal incineration. Nevertheless, it is worth noting that in Algeria only natural gas and electricity are used for domestic heating; thus, neither fossil fuel nor wood stove burning could cause the increase of n-alkanes contents in air during the winter. The n-alkane patterns were similar in downtown Algiers and Oued Smar landfill. n-Alkanes are stable enough in the atmosphere under usual conditions to undergo the same fate of aerosols carrying them. The Oued Smar area is not far from downtown Algiers, and aerosols generated in the city are exposed to the local wind regime. The aged particles that accumulated at night over the city are transported in the morning to Oued Smar by the sea breeze. Around the middle of the day, mixing of the transported pollutants with those freshly emitted by waste combustion occurs. This model is consistent with the lack of any high traffic road at Oued Smar. The transport of particles from Oued Smar to Algiers might likely be assumed especially in the late afternoon when the land breeze become active. The latter hypothesis is in
TABLE 2. Mean of n-Alkan-2-ones Concentrations (ng m-3) in Downtown Algiers and Oued Smar Landfill, during February 1999 compd tetradecanone pentadecanone hexadecanone heptadecanone octadecanone nonadecanone eicosanone total
FIGURE 3. Seasonal mean of the n-alkanoic acid concentrations (ng m-3) in downtown Algiers (a) and Oued Smar landfill (b), 19981999. agreement with that attributed to stable VOCs present in the both sites (17, 24). A possible explanation of the finding that the C16-C21 fraction was much more abundant in winter is the vaporto-particle partitioning of organic species in the atmosphere. In fact, the above n-alkanes are semivolatile (25-26) and tend, due to their vapor pressures, to accumulate drastically into the vapor phase, especially at ambient temperature as high as those reached in Algiers in the summer (up to 35 °C). Besides that, some of native particle-bound species distillate at sampling stage, thus the amounts found in samples did not entirely reproduce authentic concentrations in aerosols. This temperature effect influenced n-alkane contents more than quantitative modulation of anthropogenic emission along the year. Further investigations using backup traps are needed to better relate n-alkanes patterns to emission sources and meteorology. n-Alkanoic Acids. Figure 3 reports the concentrations found of n-alkanoic acids (A10-A30). The concentrations of the components up to A23 rose at both sides in August, but the reverse was observed for the other species. Total particulate n-alkanoic acids reached 101 and 482 ng m-3 in Oued Smar in the summer and winter, respectively, or 69 and 256 ng m-3 in downtown Algiers. All species were at anytime more abundant in Oued Smar than in downtown Algiers, but the percent composition of fractions was the same. In fact, the most abundant components belonged to the A12-A24 range, and the absolute maximums were identified with A16 and A18, depending on the time of the year. A strong even-to-odd carbon number preference was also observed, which is peculiar of natural origin. Also among acids, the most volatile species (up to A14) were prone to be lost during sampling; nevertheless, the evaporation could be disregarded for components over A16. The concentration profile of n-alkanoic acids was useful for distinguishing the true contribution of vascular plant emission from the impact of the microbial activity, which is usual in urban aerosols. In fact, acids over A22 identify high
symbol K-14 K-15 K-16 K-17 K-18 K-19 K-20
downtown Algiers
Oued Smar landfill
0.68 0.01 2.41 0.02 0.89 0.01 0.08
6.63 0.14 22.00 0.38 8.96 0.61 0.70
4.1
39.4
vegetation as a source, while the homologues comprised in the range between A12 and A20 are typical of microbial emission (27, 28). Of particular concern were the concentrations reached by both the stearic (A18) and palmitic (A16) acids. These compounds have been found in the tail pipe emissions from vehicles (29, 30) as well as in brake lining wear and paved road dusts (31). Besides that, they have been recognized as ubiquitous in the atmosphere (32), and stearic acid is used as blend component to tire rubber during manufacturing (33). Thus, the huge presence of n-alkanoic acid up to A20 in downtown Algiers might be related to anthropogenic sources including the emission from a fatty manufacturing plant sited not far from the sampling point; their dramatic accumulation in the winter strongly supports this insight. Although microbiota colonizing the epicuticular wax of plant surfaces contains acids from A13 to A20 (34), in our experiment these compounds had the additional source of marine biota (35), at least at the downtown Algiers site, which was located no more than 200 m from the sea border. Soot collected at Oued Smar was richer in acids than that of downtown Algiers. The uncontrolled open-air combustion of several organic materials especially meat burning (foodstuffs and animals) is the major source contributing to the high levels of acids in that area. In this respect, it was reported by Rogge et al. (36) that the charbroliers and meat cooking operations are an important input for monocarboxylic acids and unsaturated monocarboxylic acids. In conclusion, we believe that the presence of organic acids in the air of the Algiers region cannot be reliably reconciled to a specific origin, but we can infer that their occurrence in downtown Algiers is related to anthropogenic emissions and in the Oued Smar waste landfill is related to combustion of organic materials or microbial activity. n-Alkan-2-ones. Table 2 displays the concentrations of n-alkan-2-ones comprised in the range from K14 to K20 that were recorded in February 1999. Although the absolute contents of these components in aerosols could be affected by volatilization from samples, nevertheless the bulk of discussion seems to remain valid in our opinion. A strong even-to-odd predominance was clearly observed for these compounds. In particular, Kmax coincided with K16, which reached 2.4 and 22.0 ng m-3 in downtown Algiers and Oued Smar, respectively. Indeed, the same distribution of ketones was observed at both sites, suggesting that they originate from similar sources. n-Alkan-2-ones are known to be originated mainly by the in-situ microbial formation from n-alkanes in the R-position (37). Both the composition of their fraction and Kmax identity at the sampling sites were similar to the n-alkanoic acids in the winter (Figure 3) rather to the n-alkanes (14). This confirms our suspicion that the microbial activity originated from both of these classes of soot components. However, some contribution could be derived from resuspended soil, when it existed at significant extents (38). This should explain VOL. 35, NO. 2, 2001 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 3. PAH Concentrations (ng m-3) and Some Diagnostic Ratios in Downtown Algiers and Oued Smar Landfill, 1998-1999 downtown Algiers compound fluoranthene pyrene cyclopentapyrene benz[a]anthracene chrysene benzfluoranthenes benzo[e]pyrene benzo[a]pyrene indeno[1,2,3-cd]pyrene dibenz[a,h]anthracene benzo[ghi]perylene total nonalkylated PAHs total methyl-alkylated PAHs [FA]/([FA] + [PY]) [IPY]/([IPY] + [BPE]) [BaPY]/([BaPY] + [BePY])
Oued Smar landfill
9
downtown Algiers Oued Smar landfill compound
summer
winter
summer
winter
acridine OPAHs 9,10-anthraquinone cyclopentaphenanthrenone benzanthrone total OPAHs
ena
1.7
ndb
0.4
6.2 nd 0.8 7.0
1.0 0.6 0.4 0.2
1.5 nd 0.4 1.8
0.1 nd nd 0.1
symbol summer winter summer winter FA PY CPP BaA CHR BFAs BePY BaPY IPY DBA BPE
1.0 0.9 0.2 0.5 1.1 1.4 0.7 0.4 0.7 0.0 1.1 8.3 5.4 0.54 0.38 0.35
5.9 7.9 5.6 2.9 4.0 4.9 2.4 2.3 1.4 0.1 3.6
1.6 1.7 0.0 1.0 3.1 1.8 1.1 0.3 0.1 0.0 0.3
17.5 14.7 4.8 7.8 13.8 11.7 3.9 3.9 2.0 0.3 2.7
40.9 11.1 83.0 19.0 13.8 53.5 0.43 0.48 0.54 0.27 0.24 0.42 0.49 0.21 0.50
why at Oued Smar ketone concentrations were 1 order of magnitude greater than in downtown Algiers. In fact, the microbial formation of n-alkan-2-ones was favored at the landfill by combustion of wastes, whereas the absence of n-alkan-2-ones over eicosanone supports the hypothesis of the lack of any vascular plant wax contribution. Therefore, the municipal waste landfill played a key role in our investigation, in the perspective of discriminating the bacterial from autovehicular and biogenic sources of organic aerosols in the Algiers city area. PAHs. Table 3 shows the aerial content of individual, total nonalkylated, and methyl-alkylated PAHs both in downtown Algiers and in Oued Smar; some diagnostic ratios such as fluoranthene to the sum of fluoranthene and pyrene, indeno[1,2,3-cd]pyrene to the sum of the same compound, and benzo[ghi]perylene and benzo[a]pyrene to the sum of benzo[a]pyrene and benzo[e]pyrene are also reported. The time variability of PAH contents in downtown Algiers was highlighted by winter levels about 5 times higher than those measured in summer. The most abundant PAH in urban Algiers was pyrene in the wintertime (up to 7.9 ng m-3) and the sum of j, b, and k isomers of benzfluoranthene in summer (up to 1.4 ng m-3). The air of Oued Smar was richer in fluoranthene (up to 17.5 ng m-3) during the winter and in chrysene (3.1 ng m-3) during the summer. PAH contents in the air were anytime bigger at Oued Smar than in downtown Algiers. In Algiers, PAHs were at extent similar to those found on busy street sites in Europe (13, 39). The above diagnostic ratios were used to obtain information about the possible sources of atmospheric PAHs. The [FA]/([FA] + [PY]) ratio in downtown Algiers reached 0.42 unit and was very similar to vehicle emissions but especially to old-engine automobiles (that was not surprising, because the most of motor vehicles in Algeria are noncatalystequipped). Typical figures of the [IPy/(IPy + BPe)] ratio are reported by literature equal to 0.18 for cars, 0.37 for diesel, and 0.56 for coal (40) exhausts. By contrast, conclusive information does not yet exist about the waste burning, although some data are given in refs 41 and 42. During February, [IPy/(IPy + BPe)] ratio reached 0.3 unit in Algiers and was in agreement with motor vehicle emission and gasoline-fueled cars in particular, while numbers emerging from Oued Smar data (close to 0.4) suggested that fires of several materials caused the presence of PAHs. Independent of the nature of sources, the [BaPy]/([BaPy] + [BePy]) ratio is affected by the strong reactivity of BaPy in the atmosphere. In fact, it is prone to decomposition induced by light as well 310
TABLE 4. Concentrations of Acridine and OPAHs (ng m-3) Recorded in Soot in Downtown Algiers and at Oued Smar Landfill in August 1998 and February 1999
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a
ne, not evaluated.
b
nd, not detected.
TABLE 5. Mean NPAHs Concentrations (ng m-3) in Downtown Algiers and Oued Smar Landfill Recorded in August 1998 and February 1999 downtown Algiers compound
August symbol 1998
2-nitrofluoranthene 2-NFA 0.06 1-nitropyrene 1-NPY
