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PAH-compounds in background air (PM10) and precipitation

in Finland

Mika VesteniusAir Chemistry Laboratory

FMI

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Talk outline

-Why do we measure PAH:s?-PAH-compounds-Sampling-Analysis-Measuring campaign -Results-Conclusions

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Polycyclic aromatic hydrocarbons (PAH-compounds)

-carcinogenic compounds-ubiquitous-formed during the incomplete combustion of organic matter-emissions from wide range of combustion sourcesAnthropogenic emissions: diesel and gasoline engines, fossil fuels and biomass burning (energy production), oil refining…Natural emissions include forest fires and volcanic eruptions

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-Directive of the European parliament and the Council (2004/107/EC) requires the member states to measure PAH-compounds in thePM10-fraction in ambient air.

-Benzo(a)pyrene (BaP) shall be used as a marker for the carcinogenic risk of

PAH-compounds in ambient air and the limit values are set for benzo(a)pyrene

ng/m3 benzo[a]pyrene

Treshold value 1

Upper assessment treshold 0,6

Lower assessment treshold 0,4

Table 1: Limit values for benzo(a)pyrene

Also benzo(a)anthracene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, indeno(1,2,3-cd)pyrene, and dibenzo(a,h)anthracene must be measured.

Benzo(a)pyrene

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PAH compounds:

from Finlayson-Pitts & Pitts: Chemistry of the upper and lower atmosphere

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PAH compounds…

from Finlayson-Pitts & Pitts: Chemistry of the upper and lower atmosphere

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PAH-compounds analyzed in the FMI:

naphtalene

acenaphtylene

acenaphtene

fluorene

phenantrene

anthracene

fluoranthene

pyrene

benz(a)anthracene

chrycene

benzo(k,b,j)fluoranthene

benzo(a)pyrene

Benzo(ghi)perylene

indeno(1,2,3-cd)pyrene

dibenz(a,h)anthracene

Fig. 1: Average mass percent contributions (gas + particle phase of 13 PAH:s collected in urban air from Chicago in Feb/March 1995. (From Harner and Bidleman, 1998)

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60°N

70°N

60°N

70°N

20°E 25°E 30°E

20°E 25°E 30°E

Virolahti

Helsinki

Arctic Circle

Finland

Kuhmo

Pallas

SwedenRussian

Sampling locations

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Rainwater collection

PM10 and precipitation PAH-collectors

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Sampling Soxhlet-extraction in 60ml of CH2Cl2, minimum 8 hrs

Evaporation into 1 ml Analysis in GC-MS

The procedure

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Column:DB-5(5%Phenyl)methylpolysiloxane(non-polar)0,250 um x 0,5 mm ID x 50m

Analysis

ISTD

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Sample list

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Sample list

Starter sample blocks active places S6a sampleSTDF1 standard S7a sampleSTDA1 standard S8a sampleSTDB1 standard S9a sampleSTDC1 standard S10a sampleSTDD1 standard S6b sampleSTDE1 standard S7b sampleX1…3a quality control S8b sample

S1a sample S9b sampleS2a sample S10b sampleS3a sample STDF3 standardS4a sample STDA3 standardS5a sample STDB3 standardS1b sample STDC3 standardS2b sample STDD3 standardS3b sample STDE3 standardS4b sample x1…3c quality controlS5b sample …

STDF2 standardSTDA2 standardSTDB2 standardSTDC2 standardSTDD2 standardSTDE2 standardX1…3b quality control      

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Gas-chromatogram (SCAN)

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Gas-chromatogram (SIM)

Benzo(a)Pyrene

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LOD:s and LOQ:s

LOD = limit of detection

LOQ = limit of quantitation

MU = measurement uncertainty

PM10-fractionLOD (ng/m3)

LOQ (ng/m3) MU

naphtalene 0,011 0,037 4,6 %acenaphtylene 0,037 0,122 15,9 %acenphtene 0,007 0,024 10,5 %fluorene 0,007 0,022 17,2 %phenantrene 0,021 0,069 44,4 %anthracene 0,001 0,004 25,0 %fluoranthene 0,008 0,026 38,9 %pyrene 0,005 0,017 47,3 %benz(a)anthracene 0,004 0,015 53,7 %chrycene/triphenylene 0,001 0,004 16,7 %benzo(k+b+)fluoranthene 0,005 0,016 13,0 %benzo(a)pyrene 0,018 0,059 37,3 %benzo(ghi)perylene 0,011 0,037 46,2 %indeno(1,2,3-cd)pyrene 0,005 0,016 39,3 %dibenz(a,h+a,c)anthracene 0,007 0,023 32,0 %

MU (Uextr)2 (UISTDmeas)

2 (UGC MSanalysis(combined ))2 ...

in precipitation LOQ (ng/l)

naphtalene 2,06acenaphtylene 6,73acenphtene 1,31fluorene 1,23phenantrene 3,79anthracene 0,21fluoranthene 1,44pyrene 0,91benz(a)anthracene 0,81chrycene/triphenylene 0,23benzo(k+b+)fluoranthene 0,89benzo(a)pyrene 3,24benzo(ghi)perylene 2,03indeno(1,2,3-cd)pyrene 0,89dibenz(a,h+a,c)anthracene 1,29

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Total PAH-concentration at Virolahti. PM10 in 2007 (weekly samples)

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Benzo(a)pyrene at Virolahti PM10 in year 2007 (weekly samples)

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Benzo(a)pyrene at Virolahti, some daily PM10-samples in 2007

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PAH in precipitation at Kuhmo in 2007-2008

2007

0

2000

4000

6000

8000

10000

12000

Ap

r

Ma

y

Jun

Jul

Au

g

Se

p

Oct

No

v

De

c

Jan

Fe

b

Ma

r

Ave

rage

2008

ng

m-2

dibenz(a,h+a,c)anthracene

indeno(1,2,3-cd)pyrene

benzo(ghi)perylene

benzo(a)pyrene

benzo(k+b+j)fluoranthene

chrycene/triphenylene

benz(a)anthracene

pyrene

fluoranthene

anthracene

phenantrene

fluorene

acenphtene

acenaphtylene

naphtalene

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0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Jan Feb Mar Apr May Jun Jul Aug Sep Okt Nov Dec

2006

ng

/m2

Indeno(cd)pyrene

Benzo(ghi)perylene

Dibenso(ah)antracene

Benzo(a)pyrene

Benzo(k)fluoranthene

Benzo(b)fluoranthene

Chrysene

Benzo(a)anthracene

Pyrene

Fluoranthene

Anthracene

Phenanthrene

Total PAH -concentrations in precipitation at Pallas, monthly samples in 2006,Data from IVL

18.04.23Kainuun ilmanlaatu seminaari 12.5 2008 25

ng/l 2003   2004   2005   2007  

PAH sum min max min max min max min max

Evo (SYKE, VTT) 66 477 51 119 63 367    

Kuhmo, FMI             15 91

PAH in precipitationData from southern Finland EVO, (SYKE/VTT),May-September

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60°N

70°N

60°N

70°N

20°E 25°E 30°E

20°E 25°E 30°E

Virolahti

Helsinki

Arctic Circle

Finland

Kuhmo

Pallas

SwedenRussian

gradient

PM10 ng/m3 Total PAH B(a)P  spring

Kuhmo 1,1 0,1 2008

Virolahti 4,1 0,3 2007

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EXAMPLE: PAH-compounds in PM10- samples at Kuhmo, Selected days in spring 2008

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3.3 20083.3 2008 7.3 2008

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13.3 2008 7.4 200814.3 2008

18.04.23 3010.3 2008 18.4 2008

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Conclusions:

-Traditional analysis takes time and there is a lot of work per sample,(sample preprocessing and analysis, data processing…), but-GC-MS is highly sensitive instrument for PAH-analysisLOQ (B(a)P): 0,06 ng/m3, 0,6 ppt.

-Average PAH-concentrations in both rainwater and PM10 are highest in winter, due to heating and shortage of light-In PM10-fraction,mean PAH-concentrations were higher in Virolahti that in Kuhmo. Same thing with Benzo(a)Pyrene in PM10. Concentration gradient

-Total PAH in PM10 at Virolahti is 3,2 ng m-3. (yearly average)-Average benzo(a)pyrene concentration in PM10 at Virolahti was 0,25 ng m-3, which is under lower assessment level.-The average yearly PAH-deposition in Kuhmo is 3300 ng m-2, and the average PAH-concentration in PM10-fraction is 1.1 ng m-3. (spring 2008)

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-PAH-levels in air and in precipitation are low in Finnish background areas.-PAHs in Kuhmo come from distant sources.

Take-home messages:1. PAH-compounds are emitted to atmosphere from incomplete burning of organic compounds. 2. Offline GC-MS is labour-intensive but higly sensitive detection method for PAH-compounds in air. 3. PAH-compounds distribute to gas and aerosol phases. The distribution between the phases depends on the compounds volatility and mass. PAH-compounds containing 2-3 aromatic rings are mainly in gas phase in air, whereas compounds that have more aromatic rings go to the aerosol phase. 4. PAH-compounds decompose in photochemical reactions, which act as a sink for these compounds. These reactions are slower on the wintertime, when there is less light, compared to summertime when there is lots of light. On wintertime there is also more emissions due heating. That is why average PAH-concentrations in both PM10 and precipitation in Finland are highest on winter.

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THANK YOU!

Thank you!