temporal patterns of n-alkanes at traffic exposed and suburban sites

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Atmospheric Environment 42 (2008) 2993–3005

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Temporal patterns of n-alkanes at traffic exposed and suburbansites in Vienna

Petra Kotianovaa, Hans Puxbauma,�, Heidi Bauera, Alexandre Caseiroa,1,Iain L. Marrb, Gabriel Cıkc

aInstitute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164-AC, A-1060 Vienna, AustriabDepartment of Chemistry, University of Aberdeen, AB24 3UE Aberdeen, UK

cInstitute of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Radlinskeho 9,

812 37 Bratislava, Slovak Republic

Received 6 July 2007; received in revised form 3 December 2007; accepted 19 December 2007

Abstract

Temporal and spatial trends of particulate n-alkanes C24–C33 have been investigated at urban-fringe and traffic exposed

inner urban sites of a larger European city. The annual average sum of n-alkanes at the four sampling sites ranged from 21

to 31 ngm�3. The urban impact factor was �30% averaged over the year. The seasonal biogenic emissions of the uneven

n-alkanes cause a considerable seasonal variation in the distribution pattern of the alkanes in PM10 both in the city and

at the suburban sites. The trends in the distribution pattern can be summarized using the odd carbon preference index

CPIodd and the plant wax number %WNA, both of which show clear maxima in summer pointing to important biogenic

sources of n-alkanes. The biogenic contributions to the total n-alkanes were around 9% in winter (DJF), and 37% in

summer (JJA) at the urban-fringe sites. At the inner city sites, the urban impact is dominated by n-alkanes from

combustion sources at all seasons. A comparison of two approaches to determine the contribution of the ‘‘plant debris’’

source to ambient PM10 indicates two different mechanisms to form atmospheric ‘‘plant debris’’. The observed relative

contributions of plant debris to PM10 are well in the same range but exhibit differences in the seasonal trend. Considering

the different underlying concepts, the agreement of the derived plant debris contributions to PM10 is noteworthy.

r 2007 Elsevier Ltd. All rights reserved.

Keywords: n-Alkanes; PM10; Particulate matter; Source analysis; Biogenic particles

1. Introduction

In Europe, the ambient air quality standard forparticulates is currently defined for PM10 as a

e front matter r 2007 Elsevier Ltd. All rights reserved

mosenv.2007.12.048

ing author. Tel.: +431 58801 15170;

1 15199.

ess: [email protected] (H. Puxbaum).

ress: CESAM and Department of Environment

University of Aveiro, Campus de Santiago, 3810

al.

yearly average of 40 mgm�3, and a daily average of50 mgm�3, not to be exceed 435 times a year.However, the short-term standard is actuallyexceeded in many urban areas of Europe (e.g.,Querol et al., 2004; Van Dingenen et al., 2004;Houthuijs et al., 2001).

According to the directives 1999/30/EG and 96/62/EG of the European Commission, PM10 con-centrations have to be radically reduced by the year2010 and so the identification of the sources of the

.

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ARTICLE IN PRESSP. Kotianova et al. / Atmospheric Environment 42 (2008) 2993–30052994

particulates becomes important. Major groups ofsubstances in the particulate matter compriseinorganic ions, carbonaceous material, and mineralspecies. n-Alkanes are a subgroup of the carbonac-eous material, which can originate from both man-made and natural sources and the distributionpatterns of the homologous constituents can helpone to assess the contributors (e.g., Rogge et al.,1993a).

Particulate n-alkanes have been determined invehicle exhaust (e.g., Rogge et al., 1993b; Schauer etal., 1999a, 2002a), tyre abrasion and brake liningdust as well as in road dust (Rogge et al., 1993c).Particulate n-alkanes are emitted in natural gascombustion (Rogge et al., 1993d), from boilers(Rogge et al., 1997a), and are contained in smokefrom coal combustion (Oros and Simoneit, 2000).Hot asphalt roofing tar gives off copious amountsof higher hydrocarbons (Rogge et al., 1997b). Thesmoke of wood and synthetic logs burning isanother source of particulate n-alkanes (e.g., Roggeet al., 1998; Schauer et al., 2001; Simoneit et al.,2000; Fine et al., 2001, 2002), and also cigarettesmoke (Rogge et al., 1994; Kavouras et al., 1998).Paticulate n-alkanes were observed in cookingemissions from meat or vegetables (Rogge et al.,1991; Schauer et al., 1999b, 2002b; He et al., 2004).Vegetative detritus ranks as a ‘‘strong’’ n-alkanessource and particulate n-alkanes were reported in‘‘leave’’ abrasion (Rogge et al., 1993e). Frombiosphere, pollens and micro-organisms such asbacteria and fungal spores, and insects are known tocontribute n-alkanes (Simoneit and Eglinton, 1977).

Cooper and Bray (1963) introduced the termcarbon preference index (CPIodd) which is used toidentify the origin of the n-alkanes origin. Theinformation obtained from CPIodd and n-alkanesdistributions in different sources is discussed indetail in Gogou et al. (1998), Rogge et al. (1993a),and Simo et al. (1991). Fossil petroleum depositsshow a CPIodd value near unity and are accom-panied by a shift of the most abundant homologuesin the range C22–C25. As a result, the emissions fromutilization of fossil fuel exhibit CPIodd values closeto 1.0. While the homologues with o20 carbonsmay have a mixed origin, the presence of homo-logues with 421 carbons, with CPIodd41 andmaxima at C29–C31, does suggest a predominantbiomass input from plants. The organic matter(OM) of recent biogenic origin shows CPIodd valuesof 6–9. Urban environments, with large contribu-tion from anthropogenic emissions, generally have

CPIodd ranging from 1.0 to 2.0 (Brown et al., 2002).In addition, Simoneit et al. (1991) introduced theplant wax number (%WNA) which is deducedmainly for the directly emitted material from thevegetation rather than from resuspended soildetritus. The %WNA and CPIodd has been ob-served to correlate positively at urban areas, e.g., byLin and Lee (2004) and Zheng et al. (2000). In thispaper, we use the %WNA to derive a quantitativeestimate of plant debris contributions to PM levels.

The plant debris contribution to atmosphericorganic carbon (OC) and PM levels has beenassessed in Europe also using cellulose as ‘‘macro-tracer’’ (Puxbaum and Tenze-Kunit, 2003; Sanchez-Ochoa et al., 2007).

In this paper, we report the concentrations anddistribution patterns of the higher n-alkanes inairborne particulate samples collected at four sitesin Vienna, Austria, over a period of a year (2004).We investigate the concentrations of n-alkanes overa northwest to southeast transect across Vienna atsites more and less impacted by traffic sources,which allows us to derive an ‘‘urban impact’’ fromthe n-alkanes. We use the bulk characteristics ofn-alkanes for deriving information on direct bio-genic vs. anthropogenic combustion derived con-tributions to the n-alkanes. Then we compare twoapproaches—the plant debris derived from celluloseand derived from the wax number as proposed inthis paper—to determine the contribution of the‘‘plant debris’’ source (also named vegetativedetritus by other authors) to ambient PM10,yielding a remarkable agreement.

2. Experimental

2.1. Sampling

PM10 sampling was conducted from January toDecember 2004 at four air quality measurementstations of the Vienna air quality network (Fig. 1).Sampling was organized by the local authorities.Two of the four sites have urban-fringe character-istics. Schafbergbad is located in a park-typeresidential area (1611801000E, 4811400900N, 320ma.s.l.). The Lobau sampling site is in the area ofthe Donau Auen National Park (1613103700E,4810904500N, 150m a.s.l.). The other two samplingstations are located close to busy roads. The A23highway runs nearby the Rinnbockstrasse samplingsite (1612402800E, 4811100500N, 160m a.s.l.), while the

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Schafbergbad

Kendlerstrasse

Rinnbockstrasse

Lobau

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XXXVIIIXVIIXIV

XVI

XIII

XVVII

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I

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IVV

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XXIII X

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Fig. 1. Map of Vienna with designation of sampling sites, main traffic axis (dark grey and black lines), and water paths (white areas).

P. Kotianova et al. / Atmospheric Environment 42 (2008) 2993–3005 2995

fourth sampling site at Kendlerstrasse is beside abusy street (1611803900E, 4811202000N, 230m a.s.l.).

The PM10 samples were collected with highvolume samplers (DHA-80, DIGITEL ElectronikAG, Switzerland) on quartz fiber filters (PallflexTM

2500QAT-UP, diameter 150mm, PALL LifeSciences, USA) for 24-h sampling periods, withvolumes of approximately 700m3 per filter. Thefilters were conditioned for around 48 h in a cleanroom at a temperature of 2071 1C and a relativehumidity of 5075% and were weighed before andafter sampling. The gravimetric measurements wereperformed by the local authorities.

2.2. Chemical analyses

Analytes to be determined were n-alkanes C20–C35.One quarter of a quartz fiber filter (or an aliquot areafrom pooled filters) was taken for the extraction. Thefilter was cut into small pieces (�1.5 cm2) which werespiked with recovery standards (perdeuterated tetra-cosane C24D50 and benzo[a]pyrene-d12). The filterpieces were transferred into a glass tube and extractedtwice with 5mL of cyclohexane in a mild ultrasonicbath at room temperature each time for 5min. Theinternal standard (1-bromopentadecane) was thenadded to the combined extract, and the volume wasreduced to 200mL under a gentle stream of purenitrogen at 3575 1C. After that the extract wasanalyzed by GC–MS.

Gas chromatographic measurements were carriedout with a model HP-6890 equipped with anHP-7683 autosampler and a split/splitless injector(300 1C) was operated in splitless mode (2min).The separation was performed on a DB-5 MScapillary column (J&W Scientific) with 5%phenyl, 95% polydimethylsiloxane stationary phase(30m� 0.25mm i.d.� 0.25 mm film thickness) andpreceded by a 1m� 0.32mm uncoated fused silicapre-column. The temperature programme started at50 1C for 2min, followed by 8 1Cmin�1 to 98 1C,then 6 1Cmin�1 to 290 1C for 20min. As carrier gashelium (Messer, Vienna, Austria) suitable for traceanalysis (purity of 99.999%) was used with aconstant flow of 1.5mLmin�1. The gas chromato-graph was coupled to a quadrupole mass spectro-meter (HP-5973) operated at 70 eV in the electronionization (EI) mode. Mass spectra were recorded inthe full scan mode (m/z range: 50–550) and sensitivedetection was carried out in the selected ionmonitoring (SIM) mode. Temperature of source,quadrupole and transfer line were 230, 150, and300 1C, respectively.

For identification and quantification of n-alkanes(from SIM mode) standards of n-alkanes C20, C22,C24, C26, C28, C29, C30, and C32 (Fluka, min. 99%(GC)) were used.

The other alkanes were identified based on their EImass spectra and comparison with spectra from theNIST library, and quantified using the calibration


curve of the nearest lower carbon number n-alkane.The method detection limit defined as three timesnoise level, ranged from 2.6 pgm�3 for n-eicosane(C20) to 22.4pgm�3 for n-dotriacontane (C32), whencalculated with the average sampling volume of700m3. For practical purposes, the double of thelimit of detection or quantification was assignedto samples below the limits when computing meanand sum.

3. Results and discussion

3.1. PM10 and filter pooling

The concentrations of PM10 in the samples (on adaily base) at Rinnbockstrasse ranged from 7.8 to124 mgm�3 with an average of 33718 mgm�3. Atthe other city station, Kendlerstrasse, the valuesvaried from 6.1 to 125 mgm�3 with an average of28717 mgm�3. From the urban-fringe samplingsites PM10 concentrations were in the range4.4–95 mgm�3, average 20712 mgm�3 at the Schaf-bergbad station, and 4.1–79 mgm�3, 20716 mgm�3

at Lobau. Thus, while the annual means wereacceptable in terms of the European Directive, therewere many days showing exceedances in the periods1 January–1 April 20004 and 7 October–31 Decem-ber 2004, with 54 at Rinnbockstrasse, 36 atKendlerstrasse, 15 at Schafbergbad, but only 9 atthe Lobau sampling site.

For the chemical analyses, the daily samples weregrouped into pools. The main criteria were thePM10 concentrations in time periods of similartemporal behavior. The same time synchronizedpools were prepared for each sampling site. Somepools focused on high-PM10 ‘‘episodes’’, defined asperiods when the PM10 mass concentrations wereabove the EU short-term limit. The further poolscombined samples from ‘‘non-episode’’ days.

Altogether 52 pooled samples were obtained: 14 inJanuary, 2 in February, 4 in March, 2 in April, 2 fromMay–August, 3 in September, 8 in October, 5 inNovember, and 6 in December. One pool was missingfrom Schafbergbad (from December) and 15 poolsform Lobau (8 from January, 1 from September, 6from October), because of lack of samples.

3.2. n-Alkanes

There is no single accepted group of n-alkaneswhich should be considered for characterization ofPM10 material. Alkanes with o20 carbons are

generally considered too volatile and so would belost to varying extents from the particulate mattereven before as well as during sampling, dependingon the sampling procedure. On the other hand,those with 436 carbons can be difficult todetermine at the low levels present. In pooledsamples collected in this study, n-alkanes rangingfrom n-eicosane (C20) to n-pentatriacontane (C35)were determined to give estimates of the particulaten-alkanes present.

The concentration of total n-alkanes C20–C35 inpools sampled at the four Vienna stations variedfrom 6.88 to 127ngm�3. The concentrations ofindividual n-alkanes showed values up to 18.7 ngm�3

(Table 1).The sums of n-alkanes reported in the past for

PM10 collected at European sampling sites aredifficult to compare as different homologue selec-tions were investigated. However, the concentra-tions observed at urban sites were of a similar orderof magnitude to those observed at clean ruralsites. For example, 37–205 ngm�3 were reportedfrom an industrialized area in Prato (Italy, samplingperiod May 2000–January 2001, n-alkane rangeC13–C34) (Cincinelli et al., 2003), 16–262 ngm

�3 atan urban/industrial influenced grassland locationin Melpitz (Germany, April–May 2001, C16–C34)(Alves et al., 2006), and 7.2–95 ngm�3 at Hyytiala, aforest site (Finland, August 2001, C16–C34) (Alveset al., 2006).

Normal alkanes are released from anthropogenicand biogenic sources in the range C12–C40 and theconcentration range of a particular compound canbe wide, e.g., the mean concentrations of tricosane(C23) determined by Kubatova et al. (2002) in Ghentwere 8.6714.1 ngm�3 in winter and 1.272.0 ngm�3

in summer 1998. The concentration variation oforganic species in the aerosols is generally consid-ered to be a consequence of the semi-volatile natureof some components, meteorological conditions(may influence the particle-gas phase partitioningand deposition of aerosols), chemical characteristicsafter emission, as well as by changes in the sourcecontributions.

The distribution pattern of the n-alkanes in theairborne particulates over Vienna is shown in Fig. 2.In all four cases, summer (April–September) andwinter (January–March, October–December), cityand suburban there can be seen peaks superimposedon a smooth curved background. The smoothbackground distribution is much higher in theurban samples than in the suburban samples, and

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0

1

2

3

4

5

C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 C33 C34 C35

c [

ng/m

3]

urban, winter suburban, winter urban, summer suburban, summer

compound

Fig. 2. Pattern of n-alkanes in winter and summer season at urban (average of Rinnbockstrasse and Kendlerstrasse) and suburban

(average of Schafbergbad and Lobau) sampling sites.

Table 1

Concentration of n-alkanes (ngm�3) at the Vienna sampling sites in 2004

Compound name Rinnbockstrasse Kendlerstrasse Schafbergbad Lobau

AV MAX AV MAX AV MAX AV MAX

n-Eicosane 0.50 4.69 0.27 2.45 0.21 2.23 0.16 1.76

n-Heneicosane 1.09 13.9 0.56 7.01 0.38 6.48 0.30 4.92

n-Docosane 1.69 18.7 1.07 14.2 0.68 13.3 0.60 8.06

n-Tricosane 1.99 16.5 1.49 14.9 0.91 13.8 0.87 8.93

n-Tetracosane 2.09 12.7 1.81 12.0 1.19 11.5 1.13 7.77

n-Pentacosane 2.71 9.90 2.51 11.4 1.73 9.64 1.90 7.18

n-Hexacosane 2.52 9.28 2.36 9.57 1.74 8.77 1.54 6.08

n-Heptacosane 4.04 9.39 3.69 11.1 2.95 9.77 3.53 8.52

n-Octacosane 2.53 6.84 2.51 7.41 1.97 6.86 1.65 7.08

n-Nonacosane 4.94 13.5 4.72 12.2 3.92 9.61 3.99 15.7

n-Triacontane 2.41 5.52 2.42 8.45 1.76 5.30 1.50 8.75

n-Hetriacontane 4.62 13.7 4.12 11.1 2.77 8.06 2.60 12.4

n-Dotriacontane 2.57 4.64 2.51 6.41 1.96 4.48 1.59 6.33

n-Tritriacontane 2.74 5.90 2.22 5.84 2.06 4.51 1.39 5.71

n-Tetratriacontane 0.62 4.81 0.49 3.60 0.21 3.01 0.17 3.71

n-Pentatriacontane 0.69 7.49 0.28 3.02 0.10 1.71 0.09 1.70

Total n-alkanes C20–C35, range 21.0–127 18.4–126 6.88–114 15.1–76.7

Total n-alkanes C24–C33, range 18.9–79.1 16.8–86.9 3.9–77.9 12.9–68.6

Total n-alkanes C24–C33, AV 31.2 28.9 22.0 20.8

S.D. 5.45 6.65 5.64 4.56

AV, yearly average; MAX, maximum in individual pool; S.D., standard deviation of total n-alkanes C24–C33 monthly means.


is at a maximum in winter. This is likely a result ofemissions from urban ‘‘winter’’ sources, such asdomestic heating (e.g., natural gas, oil, and woodcombustion). The main components are always C27,C29, and C31 considered to originate from plantmaterial are the main components, but they aremore pronounced in the summer samples than in

those from winter. The predominance of n-alkanesC27, C29, or C31 has been reported for other sites inEurope, e.g., in Portugal (Alves et al., 2001),Germany (Alves et al., 2006), and Finland (Alveset al., 2006; Rissanen et al., 2006).

Since the C10–C23 n-alkanes are semi-volatile (e.g.,Kadowaki, 1994), they are not further considered


here. n-Alkanes4C33 generally occur at very lowconcentrations (Fig. 2), thus we also excluded themfrom the long term study. The range of C24–C33 iscalled the higher plant wax range. In this range,n-alkanes originate from both natural and man-madesources, and it is possible to discriminate theinfluence from those two groups of sources byinvestigating the uneven/even relationships of thesamples.

Table 1 shows the annual mean concentrations ofn-alkanes, as well as sum of n-alkanes C24–C33, andstandard deviations of monthly means. The twoinner city sites do have higher concentrations thanthe two urban-fringe sites, and the difference istaken as the urban impact for the n-alkanes which inthis case is 28.6%.

The total n-alkanes C24–C33 concentration variedin individual pools from 16.8 to 86.9 ngm�3 at

0.00

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M10

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% o

f O

M

Rinnböckstrasse Kendlers

Rinnböckstrasse Kendlers

Fig. 3. (a) Total n-alkanes C24–C33 as a % of PM10 mass.

traffic exposed sampling sites, and from 3.9 to77.9 ngm�3 at sampling sites with urban-fringecharacteristics (Table 1). The maximum values wereobserved in the pool from January (8 January 2004).

The mass content of n-alkanes in PM10calculated as the ratio of mass of n-alkanesC24–C33 to the mass of PM10 is, for individualpools, usually in the range 0.05–0.15%. Somewhathigher values appeared in the warm season fromMay to September with a maximum of 0.34% forKendlerstrasse (Fig. 3a).

Similarly, the mass content of n-alkanes in OMwas calculated (see Fig. 3b). n-Alkanes C24–C33

accounted for 0.37–0.43% of the total OM as anaverage of individual pools, at all four sites, with thelowest contribution at Rinnbockstrasse which couldbe explained by the higher proportion of OM fromnearby traffic. OM was calculated from OC as

06-0

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pool

trasse Lobau

trasse Schafbergbad Lobau

pool

Schafbergbad

(b) Total n-alkanes C24–C33 as a % of organic matter.

ARTICLE IN PRESSP. Kotianova et al. / Atmospheric Environment 42 (2008) 2993–3005 2999

OM ¼ 1.7�OC (Bauer et al., 2006) where OC wasdetermined according method described earlier bySalam et al. (2003). Thus, the n-alkanes of interestrepresent only minor constituents of OM, at themost of 1.05% in the Vienna area. The interest inanalysing the samples for these compounds stemstherefore more from the information which theycould reveal than from their importance as indivi-dual components of the PM10.

Higher concentrations of total n-alkanes C24–C33

were found in the samples with higher concentra-tions of PM10 in the atmosphere. Fig. 4 shows thatthe total C24–C33 n-alkane values correlate with thePM10 mass concentrations.

0

20

40

60

80

100

120

0 20 40

c [ng/m

3]

Rinnböckstrasse Kendlerstr

Rinnböckstrasse: c = 0.499PM10

Kendlerstrasse: c = 0.558PM10

Schafbergbad: c = 0.504PM10

Lobau: c = 0.543PM10

PM10

Fig. 4. Correlation between total n-alkanes C24–C33 concen

-10

0

10

20

30

40

50

01 02 03 04 05 06

c [

ng/m

3]

Rinnböckstrasse K

Lobau U

m

Fig. 5. Monthly averages of total n-alkan

3.3. Seasonal variation and origin of n-alkanes

Fig. 5 shows the variation in total n-alkanes at thedifferent sites throughout the year on a month-by-month basis. The first impression is that theseasonal variation is small, with slightly highervalues in the winter period. The urban impact isremarkably constant. The monthly mean concen-trations of total n-alkanes C24–C33 at the Viennasampling sites varied from 12.6 to 39.3 ngm�3. Thelowest urban impact was observed in May and June,when the concentrations of total n-alkanes C24�C33

at the inner city sampling sites were very similar toconcentrations at sampling sites with urban-fringe

60 80 100 120

asse Lobau

+ 15.8 R2 = 0.75

+ 15.0 R2 = 0.63

+ 11.2 R2 = 0.63

+ 13.0 R2 = 0.47

[µg/m3]

Schafbergbad

trations and PM10 concentrations in individual pools.

07 08 09 10 11 12

endlerstrasse Schafbergbad

rban Impact

onth

es at Vienna sampling sites (2004).


characteristics. On the other hand, the highesturban impact was observed in April.

The CPIodd is expressed as concentration ratio ofn-alkanes with odd and even carbon number:CPIodd ¼

P[odd carbon number n-alkanes]/

P[even

carbon number n-alkanes]. In our case, the CPIodd iscalculated for the so-called higher plant wax CPIsplit range. The values are higher than those obtainedfor whole range as, for example, C12–C35 (e.g., Alveset al., 2001, 2006; Harrad et al., 2003). The CPIoddfor the Vienna samples shows a considerableseasonal variation (Table 2). The values are in rangeof 0.93–1.31 in the cold season (January, February,and December 2004) for all sampling sites. Themaximum was observed in July, when the CPIodd wasaround 2.67 at Rinnbockstrasse and Kendlerstrasseand around 3.43 at Schafbergbad and Lobau. Wecan also see a different CPIodd index for the neartraffic sampling cites in comparison to the samplingsites on the Vienna urban-fringe sites.

Although all through along the year 2004 inVienna the main components were n-alkanes withodd carbon number C27, C29, and C31, the CPIoddvalues show clearly seasonal differences in then-alkanes composition. At Rinnbockstrasse andKendlerstrasse, we can see a strong contributionfrom anthropogenic emissions. The influence ofbiogenic emissions became clear only in July, whenthe CPIodd was 42.0. At sampling sites with urban-fringe characteristics, such values were observed inthe warm season from May to August.

In spite of lower concentrations of n-alkanes inthe atmosphere in the warm season, their contribu-tion to PM10 (in percentage) is slightly higher andthe CPIodd increased. This implies a very strongcontribution of biogenic sources during the warmseason at all sampling sites. These deductions can beverified by plant wax number values.

The contribution of plant wax n-alkanes(%WNA) is calculated as follows (Simoneit, 1989):

%WNA ¼

Pð½Cn� � 0:5ð½Cnþ1� þ ½Cn�1�ÞÞP

n� alkanes� 100%

where negative values of the numerator are taken aszero. The plant wax number calculation assumes thewax n-alkanes are directly emitted from the vegeta-tion and not in part from resuspended soil detritus(Simoneit et al., 1991).

The %WNA observed in this study show thesame trend as CPIodd (Table 2). The values arehigher in the warm season than in the cold season,

and the inner city sampling sites have lower waxnumbers than the urban-fringe stations.

The %WNA number of 9% suggest that around81% of n-alkanes C24–C33 at Vienna sampling sitesdetermined in PM10 ambient aerosol samples inwinter months (December, January, February) werefrom petroleum residues rather than from higherplant wax, whereas it was only �63% in summermonths (June–August).

In our case, correlation coefficient r2 between%WNA and CPIodd of 0.93–0.94 was observed attraffic-exposed sites, while at sites with urban-fringecharacteristics r2 reached values of 0.86 forSchafberbad and of 0.91 for Lobau, because in July%WNA did not increased proportional to CPIodd.

Values of urban impact CPIodd and %WNA arelisted in Table 2. Monthly values were calculated frommonthly mean concentrations of individual n-alkanes.Negative values of urban impact which occurred forsome analytes in February, May, and June were takenas zero. Carbon preference index of urban impact isrelatively constant and typical values are in the rangefrom 1.1 to 1.8. The %WNA values showed that13–42% n-alkanes C24–C33 emitted in Vienna shouldcome from vegetation. In the urban impact, bothcharacteristics are correlated with r2 of 0.71, when‘‘problematic’’ months are not considered. Analo-gously obtained yearly mean urban impact CPIodd and%WNA clearly show that aerosols emitted at innercity sampling sites have anthropogenic character.

3.4. Biogenic emissions contribution to PM10

The contribution of plant debris, respectivelyvegetative detritus, to OC or PM levels has beenderived in the past by use of CMB models (e.g.,Schauer et al., 2002c; Zheng et al., 2002) and byusing cellulose as macrotracer (Puxbaum andTenze-Kunit, 2003; Sanchez-Ochoa et al., 2007).Here, we compare the results from the cellulosetracer with results obtained with a factor derivedfrom the waxy contribution of n-alkanes combinedwith n-alkanes data from plant debris ‘‘profile’’ datafrom Rogge et al. (1993e).

The portion of the plant debris in the aerosolfrom the cellulose value (PDCEL) is proposed to beestimated by the following equation, which takes inaccount the cellulose content in leaves and the wayof cellulose determination:

PDCEL ¼FC

0:72� 2,

ARTICLE IN PRESS

Table 2

Monthly means of carbon preference index (CPIodd) and plant wax number (%WNA) from Vienna samplings sites

Month Rinnbockstrasse Kendlerstrasse Schafbergbad Lobau Urban impact

CPIodd %WNA CPIodd %WNA CPIodd %WNA CPIodd %WNA CPIodd %WNA

January 1.14 12.7 1.19 12.9 1.13 11.3 1.15 14.4 1.20 12.9

February 1.08 6.8 0.93 9.7 1.06 3.8 1.03 3.4 1.14 16.7

March 1.33 15.4 1.28 12.6 1.17 7.8 1.05 10.3 1.73 24.1

April 1.78 26.0 1.42 16.2 1.54 18.0 1.77 25.3 1.47 18.9

May 2.00 29.3 1.90 27.5 2.65 42.8 2.78 44.4 1.42 39.7

June 2.10 36.9 2.09 31.3 2.62 42.2 2.29 44.3 0.76 37.7

July 2.63 39.0 2.70 41.2 3.56 40.4 3.29 47.8 1.53 31.4

August 2.07 31.0 1.73 24.5 1.94 30.3 2.52 39.3 1.17 13.2

September 1.69 22.1 1.86 31.8 1.58 18.8 2.04 36.2 1.72 26.1

October 1.62 21.3 1.61 20.3 1.61 20.0 1.60 20.2 1.65 22.6

November 1.45 15.0 1.26 17.0 1.27 10.3 1.44 19.3 1.36 24.0

December 1.31 11.1 1.23 8.7 1.14 6.1 1.00 6.7 3.89 41.6

Yearly average 1.57 20.9 1.49 19.4 1.56 19.6 1.81 28.7 1.23 13.1


where FC is concentration of ‘‘free cellulose’’ inatmospheric aerosol samples; for details see Pux-baum and Tenze-Kunit (2003).

For the determination of plant debris based onthe concentration of biogenic n-alkanes concentra-tions in the atmospheric aerosols PDALK, thefollowing formula was used:

PDALK ¼

Pn� alkanes� ð%WNA=100Þ

0:0236.

The biological fraction of n-alkanes is expected tocome exclusively from plant debris as the contribu-tions from other source (e.g., pollen, bacteria, andinsect) are supposed to be negligible. The content ofn-alkanes material varies in a wide range fromdifferent plant species (e.g., Maffei et al., 2004;Maffei, 1996). For the determination of PDALK, themean value of n-alkane concentrations of ‘‘greenleaves’’ and ‘‘dead leaves’’ reported by Rogge et al.(1993e) was used (yielding a factor of 0.0236).

The PDCEL and the PDALK values were used tocalculate the percentage of PM10 derived fromplant debris. The %PD-cel, %PD-alk values arewithin the same range, but the absolute values andthe patterns were not identical (Fig. 6). The %PD-alk values were lower in winter and higher insummer than the %PD-cel. A maximum of 3.6% of%PD-alk was found at the urban-fringe samplingsite Lobau in May. The %PD-cel values were moresimilar for all Vienna sampling sites and did notexceed a value of 2% (with one exception forSchafbergbad in January). It can be concluded that,

although plant debris contributions to PM10 arenot high, it is a non-negligible source.

The differences between results obtained bycalculation from cellulose and from n-alkanes couldbe caused by several factors. For the plant debriscalculation with cellulose as tracer is has to beconsidered that cellulose originates from the bulkmaterial of plant debris. For the conversion ofmeasured ‘‘free cellulose’’ values to the PDCEL twofactors are used which have to be considered whenassessing the uncertainty of the results. A factor of0.72 is used for conversion of ‘‘free cellulose’’ to‘‘total cellulose’’ with a standard deviation of 0.16%(Puxbaum and Tenze-Kunit, 2003). A factor of 2 istaken for conversion of cellulose to plant material asderived from the cellulose content of ‘‘green leaves’’of approximately 50% (Puxbaum and Tenze-Kunit,2003; Kunit and Puxbaum, 1996). Moreover, ‘‘deadleaves’’ may contain less cellulose than green leaves,since cellulose is degraded faster than lignin. Thecellulose might be partly resuspended to the atmo-sphere. Drewnik (2006) reported a high variabilityin cellulose degradation kinetics in soil when after10 weeks 22–98%, and after 1 year 48–100% weredecomposed. Sanchez–Ochoa et al. (2007) estimatedthe over all uncertainty of the plant debris valuesfrom cellulose by 37%. The plant debris calculationaccording to the n-alkane signal also used twofactors. %WNA values should refer the n-alkanespercentage from plant debris. Simoneit et al. (1991)notice that the %WNA calculation assumes the waxn-alkanes are directly from vegetation and not inpart from resuspended soil detritus. However, the

ARTICLE IN PRESS

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

01 02 03 04 05 06 07 08 09 10 11 12

month

%P

D-c

el

Rinnböckstrasse Kendlerstrasse Schafbergbad Lobau

Rinnböckstrasse Kendlerstrasse Schafbergbad Lobau

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

01 02 03 04 05 06 07 08 09 10 11 12

%P

D-a

lk

month

Fig. 6. (a) Plant debris as a percentage of PM10 determined via cellulose. (b) Plant debris as a percentage of PM10 determined via n-

alkanes.

P. Kotianova et al. / Atmospheric Environment 42 (2008) 2993–30053002

%WNA values dedicated from Rogge et al. (1993e)gave very similar values for ‘‘green’’ and ‘‘deadleaves’’. The ‘‘emission’’ factor of 0.0236 carriesuncertainty as it might be derived from a limitednumber of plant species. Its advantage is, however,that it covers emissions from ‘‘green’’ as well as‘‘dead leaves’’ and included abrasive material fromleaves, conifers, grasses, etc.

Thus, we conclude that cellulose is a substancerepresentative for the ‘‘total’’ plant material whilewaxes originate from the plant surfaces.

The mechanism to form atmospheric cellulose israther grinding and degradation, for n-alkanes, itseems to be the material rubbing off the surface ofthe leaves.

Since the mechanisms of forming atmosphericcellulose and atmospheric plant wax particles aredifferent, it is not expected that the results will agree

perfectly. However, considering two different un-derlying processes, the agreement observed is in thesame range and still remarkable.

4. Conclusions

�
The annual mean concentrations of totaln-alkanes were higher at the inner city samplingsites than at urban-fringe sampling sites; theurban impact adds in average 30% to n-alkaneslevels at traffic exposed city sites. � n-Alkanes represent up to 0.34% of PM10 and
1.05% of OM.
� There is a strong correlation (r240.63) between
total n-alkane concentrations and mass concen-trations of PM10 at the city sites.
� Individual n-alkanes exhibit a strong seasonal
variation; relative composition of total n-alkanes


is similar at sampling sites and varied morewith time than with location; the predominantn-alkanes are C27, C29, and C31.
� CPIodd and %WNA (plant wax) values showed
predominant contributions of anthropogenicsources during the cold season, and of biogenicsources during the warm season; the influence ofbiogenic sources is higher at sampling sites withurban-fringe characteristics.
� Urban impact CPIodd of 1.23 and urban impact
%WNA of 13.1% calculated from yearly meanconcentrations of n-alkanes C24–C23 indicate thatemissions in the area of Vienna city have mainlyanthropogenic character.
� The comparison of two approaches to determine
the contribution of the ‘‘plant debris’’ source toambient PM10 indicates two different mechan-isms to form atmospheric ‘‘plant debris’’. Theobserved relative contributions of plant debris toPM10 are in the same range. The seasonality withhigher values during the vegetative period ismore pronounced for the data derived from then-alkanes. However, considering the differentunderlying concepts, the agreement of the de-rived plant debris contributions to PM10 isremarkable.

Acknowledgments

This work is part of the project AQUELLAVienna funded by the MA22—EnvironmentalProtection of the City of Vienna. We are gratefulto AQUELLA members, namely Parissa Poures-maeil and Blanca Lorena Andrare Sanchez forlogistic help.

References

Alves, C., Pio, C., Duarte, A., 2001. Composition of extractable

organic matter of air particles from rural and urban

Portuguese areas. Atmospheric Environment 35, 5485–5496.

Alves, C., Pio, C., Carvalho, A., Santos, C., 2006. Atmospheric

carbonaceous aerosols over grasslands of central Europe and

a Boreal forest. Chemosphere 63, 153–164.

Bauer, H., Marr, I., Kasper-Giebl, A., Limbeck, A., Caseiro, A.,

Handler, M., Jankowski, N., Klatzner, B., Kotianova, P.,

Pouresmaeil, P., Schmidl, Ch., Sageder, M., Puxbaum H.,

2006. AQUELLA—TEAM. Final Report of the Project

‘‘AQUELLA,’’ Vienna. [in German], TU Vienna, Institute 164.

Brown, S.G., Herckes, P., Ashbaugh, L., Hannigan, M.P.,

Kreidenweis, S.M., Collett Jr., J.L., 2002. Characterization

of organic aerosol in Big Bend National Park, Texas.

Atmospheric Environment 36, 5807–5818.

Cincinelli, A., Mandorlo, S., Dickhut, R.M., Lepri, L., 2003.

Particulate organic compounds in the atmosphere surround-

ing an industrialised area of Prato (Italy). Atmospheric

Environment 37, 3125–3133.

Drewnik, M., 2006. The effect of environmental conditions on the

decomposition rate of cellulose in mountain soils. Geoderma

132, 116–130.

Fine, P.M., Cass, G.R., Simoneit, B.R.T., 2001. Chemical

characterisation of fine particle emissions from fireplace

combustion of woods grown in the Northeastern United

States. Environmental Science and Technology 35,

2665–2675.

Fine, P.M., Cass, G.R., Simoneit, B.R.T., 2002. Chemical

characterisation of fine particle emissions from fireplace

combustion of woods grown in the Southern United States.

Environmental Science and Technology 36, 1442–1451.

Gogou, A.I., Apostolaki, M.A., Stephanou, E.G., 1998.

Determination of organic molecular markers in marine

aerosols and sediments: one-step flash chromatography

compound class fractionation and capillary gas chromato-

graphic analysis. Journal of Chromatography A 799,

215–231.

Harrad, S., Hassoun, S., Romero, M.S.C., Harrison, R.M., 2003.

Characterisation and source attribution of the semi-volatile

organic component of atmospheric particles and associated

vapour phase in Birmingham, UK. Atmospheric Environ-

ment 37, 4985–4991.

He, L., Hu, M., Huang, X., Yu, B., Zhang, Y., Liu, D., 2004.

Measurement of emissions of fine particulate organic matter

from Chinese cooking. Atmospheric Environment 38,

6557–6564.

Houthuijs, D., Breugelmans, O., Hoek, G., Vaskovi, E.,

Mihalikova, E., Pastuszka, J.S., Jirik, V., Sachelarescu, S.,

Lolova, D., Meliefste, K., Uzunova, E., Marinescu, C., Volf,

J., de Leeuw, F., van de Wiel, H., Fletcher, T., Lebret, E.,

Brunekreef, B., 2001. PM10 and PM2.5 concentrations in

Central and Eastern Europe: results from the Cesar study.

Atmospheric Environment 35, 2757–2771.

Kadowaki, S., 1994. Characterization of carbonaceous aerosols

in the Nagoya urban area. 2. Behavior and origin of

particulate n-alkanes. Environmental Science and Technology

28, 129–135.

Kavouras, I.G., Stratigas, N., Stephanou, E.G., 1998. Iso- and

anteiso-alkanes: specific tracers of environmental tobacco

smoke in indoor and outdoor particle-size distributed urban

aerosols. Environmental Science and Technology 32,

1369–1377.

Kubatova, A., Vermeylen, R., Claeys, M., Cafmeyer, J.,

Maenhaut, W., 2002. Organic compounds in urban

aerosols from Gent, Belgium: characterization, sources, and

seasonal differences. Journal of Geophysical Research 107

(D21), 8343.

Kunit, M., Puxbaum, H., 1996. Enzymic determination of the

cellulose content of atmospheric aerosols. Atmospheric


Lin, J.J., Lee, L., 2004. Characterization of n-alkanes in urban

submicron aerosol particles (PM1). Atmospheric Environ-

ment 38, 2983–2991.

Maffei, M., 1996. Chemotaxonomic significance of leaf wax

n-alkanes in the Umbelliferae, Cruciferae and Leguminosae

(subf. Papilionoideae). Biochemical Systematics and Ecology

24, 531–545.


Maffei, M., Badino, S., Bosi, S., 2004. Chemotaxonomic

significance of leaf wax n-alkanes in the Pinales (Coniferales).

Journal of Biological Research 1, 3–19.

Oros, D.R., Simoneit, B.R.T., 2000. Identification and emission

rates of molecular tracers in coal smoke particulate matter.

Fuel 79, 515–536.

Puxbaum, H., Tenze-Kunit, M., 2003. Size distribution and

seasonal variation of atmospheric cellulose. Atmospheric


Querol, X., Alastuey, A., Ruiz, C.R., Artinano, B., Hansson,

H.C., Harrison, R.M., Buringh, E., ten Brink, H.M., Lutz,

M., Bruckmann, P., Straehl, P., Schneider, J., 2004. Specia-

tion and origin of PM10 and PM2.5 in selected European

cities. Atmospheric Environment 38, 6547–6555.

Rissanen, T., Hyotylainen, T., Kallio, M., Kronholm, J.,

Kulmala, M., Riekkola, M.-L., 2006. Characterization of

organic compounds in aerosol particles from a coniferous

forest by GC–MS. Chemosphere 64, 1185–1195.

Rogge, W.F., Hildemann, L.M., Mazurek, M.A., Cass, G.R.,

Simoneit, B.R.T., 1991. Sources of fine organic aerosol. 1.

Charbroilers and meat cooking operations. Environmental

Science and Technology 25, 1112–1125.

Rogge, W.F., Mazurek, M.A., Hildemann, L.M, Cass, G.R.,

Simoneit, B.R.T., 1993a. Quantification of urban organic

aerosols at a molecular level: identification, abundance

and seasonal variation. Atmospheric Environment 27A,

1309–1330.


Simoneit, B.R.T., 1993b. Sources of fine organic aerosol. 2.

Noncatalyst and catalyst-equipped automobiles and heavy-

duty diesel trucks. Environmental Science and Technology 27,

636–651.


Simoneit, B.R.T., 1993c. Sources of fine organic aerosol. 3.

Road dust, tire debris, and organometallic brake lining dust:

roads as sources and sinks. Environmental Science and

Technology 27, 1892–1904.


Simoneit, B.R.T., 1993d. Sources of fine organic aerosol. 5.

Natural gas home appliances. Environmental Science and

Technology 27, 2736–2744.

Rogge, W.F., Mazurek, M.A., Hildemann, L.M., Cass, G.R.,

Simoneit, B.R.T., 1993e. Sources of fine organic aerosol. 4.

Particulate abrasion products from leaf surfaces of urban

plants. Environmental Science and Technology 27,

2700–2711.



Cigarette smoke in the urban atmosphere. Environmental



Simoneit, B.R.T., 1997a. Sources of fine organic aerosol. 8.

Boilers burning No. 2 distillate fuel oil. Environmental



Simoneit, B.R.T., 1997b. Sources of fine organic aerosol. 7.

Hot asphalt roofing tar pot fumes. Environmental Science

and Technology 31, 2726–2730.



Pine, oak, and synthetic log combustion in residential

fireplaces. Environmental Science and Technology 32, 13–22.

Salam, A., Bauer, H., Kassin, K., Ullah, S.M., Puxbaum, H.,

2003. Aerosol chemical characteristics of a mega-city in

Southeast Asia (Dhaka, Bangladesh). Atmospheric Environ-

ment 37, 2517–2528.

Schauer, J.J., Kleeman, M.J., Cass, G.R., Simoneit, B.R.T.,

1999a. Measurement of emissions from air pollution sources.

2. C1 through C30 organic compounds from medium duty

diesel trucks. Environmental Science and Technology 33,

1578–1587.


1999b. Measurement of emissions from air pollution

sources. 1. C1 through C29 organic compounds from meat

charbroiling. Environmental Science and Technology 33,

1566–1577.

Schauer, J.J., Kleeman, M.J., Cass, G.R., Simoneit, B.R.T., 2001.

Measurement of Emissions from air pollution sources. 3.

C1–C29 organic compounds from fireplace combustion of

wood. Environmental Science and Technology 35, 1716–1728.


2002a. Measurement of emissions from air pollution sources.

5. C1–C32 organic compounds from gasoline-powered

motor vehicles. Environmental Science and Technology 36,

1169–1180.


2002b. Measurement of emissions from air pollution sources.

4. C1–C27 organic compounds from cooking with seed oils.


Schauer, J.J., Fraser, M.P., Cass, G.R., Simoneit, B.R.T., 2002c.

Source reconcilation of atmospheric gas-phase and particle-

phase pollutants during a severe photochemical smog episode.


Simo, R., Colom-Altes, M., Grimlt, J.O., Albaiges, J., 1991.

Background levels of atmospheric hydrocarbons, sulfate and

nitrate over the western Mediterranean. Atmospheric Envir-

onment 25A, 1463–1471.

Simoneit, B.R.T., 1989. Organic matter of the troposphere—V.

Application of molecular marker analysis to biogenic emis-

sions into the troposphere for source reconciliations. Journal

of Atmospheric Chemistry 8, 251–275.

Simoneit, B.R.T., Eglinton, G., 1977. Organic matter of eolian

dusts and its input to marine sediments. In: Campos, R.,

Goni, J. (Eds.), Advances in Organic Geochemistry.

ENADIMSA, Madrid, pp. 415–430.

Simoneit, B.R.T., Sheng, G., Chen, X., Fu, J., Zhang, J., Xu, Y.,

1991. Molecular marker study of extractable organic matter

in aerosols from urban areas of China. Atmospheric

Environment 25A, 2111–2129.

Simoneit, B.R.T., Rogge, W.F., Lang, Q., Jaffe, R., 2000.

Molecular characterisation of smoke from campfire burning

of pine wood (Pinus elliottii). Chemosphere: Global Change

Science 2, 107–122.

Sanchez-Ochoa, A., Kasper-Giebl, A., Puxbaum, H., Gelencser,

A., Legrand, M., Pio, C., 2007. Concentration of atmospheric

cellulose: a proxy for plant debris across a west–east

transect over Europe. Journal of Geophysical Research 112,

D23S08.

Van Dingenen, R., Raes, F., Putaud, J., Baltensperger, U.,

Charron, A., Facchini, M., Decesari, S., Fuzzi, S., Gehrig, R.,

Hansson, H., Harrison, R.M., Hueglin, C., Jones, A.M., Laj,

P., Lorbeer, G., Maenhaut, W., Palmgren, F., Querol, X.,

Rodriguez, S., Schneider, J., Ten Brink, H., Tunved, P.,

Torseth, K., Wehner, B., Weingartner, E., Wiedensohler, A.,


Wahlin, P., 2004. A European aerosol phenomenology. 1.

Physical characteristics of particulate matter at kerbside,

urban, rural and background sites in Europe. Atmospheric


Zheng, M., Fang, M., Wang, F., To, K.L., 2000. Characteriza-

tion of the solvent extractable organic compounds in PM2.5

aerosols in Hong Kong. Atmospheric Environment 34,

2691–2702.

Zheng, M., Cass, G.R., Schauer, J.J., Edgerton, E.S., 2002.

Source apportionment of PM2.5 in the Southeastern United

States using solvent-extractable organic compounds. Envir-

onmental Science and Technology 36, 2361–2371.

temporal patterns of n-alkanes at traffic exposed and suburban sites

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