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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
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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!