PAH-compounds in background air (PM10)

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PAH-compounds in background air (PM10) and
precipitation in Finland Mika Vestenius Air
Chemistry Laboratory FMI
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Talk outline
-Why do we measure PAHs? -PAH-compounds -Sampling
-Analysis -Measuring campaign -Results -Conclusi
ons
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Polycyclic aromatic hydrocarbons
(PAH-compounds) -carcinogenic compounds -ubiquito
us -formed during the incomplete combustion of
organic matter -emissions from wide range of
combustion sources Anthropogenic 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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Benzo(a)pyrene
-Directive of the European parliament and the
Council (2004/107/EC) requires the member states
to measure PAH-compounds in the PM10-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
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.
Table 1 Limit values for benzo(a)pyrene
ng/m3 benzoapyrene
Treshold value 1
Upper assessment treshold 0,6
Lower assessment treshold 0,4
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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 PAHs collected in urban air
from Chicago in Feb/March 1995. (From Harner and
Bidleman, 1998)
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Sampling locations
?
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Rainwater collection
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PM10 and precipitation PAH-collectors
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The procedure
Sampling
Soxhlet-extraction in 60ml of CH2Cl2, minimum 8
hrs
Evaporation into 1 ml
Analysis in GC-MS
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Analysis
Column DB-5 (5Phenyl) methylpolysiloxane (non-po
lar) 0,250 um x 0,5 mm ID x 50m
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ISTD
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Sample list
Sample list Sample list Sample list Sample list Sample list

Starter sample blocks active places S6a sample
STDF1 standard S7a sample
STDA1 standard S8a sample
STDB1 standard S9a sample
STDC1 standard S10a sample
STDD1 standard S6b sample
STDE1 standard S7b sample
X13a quality control S8b sample
S1a sample S9b sample
S2a sample S10b sample
S3a sample STDF3 standard
S4a sample STDA3 standard
S5a sample STDB3 standard
S1b sample STDC3 standard
S2b sample STDD3 standard
S3b sample STDE3 standard
S4b sample x13c quality control
S5b sample
STDF2 standard
STDA2 standard
STDB2 standard
STDC2 standard
STDD2 standard
STDE2 standard
X13b quality control      
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Gas-chromatogram (SCAN)
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Gas-chromatogram (SIM)
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Benzo(a)Pyrene
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LODs and LOQs
PM10-fraction LOD (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(kb)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,ha,c)anthracene 0,007 0,023 32,0
in precipitation  LOQ (ng/l)
naphtalene 2,06
acenaphtylene 6,73
acenphtene 1,31
fluorene 1,23
phenantrene 3,79
anthracene 0,21
fluoranthene 1,44
pyrene 0,91
benz(a)anthracene 0,81
chrycene/triphenylene 0,23
benzo(kb)fluoranthene 0,89
benzo(a)pyrene 3,24
benzo(ghi)perylene 2,03
indeno(1,2,3-cd)pyrene 0,89
dibenz(a,ha,c)anthracene 1,29
LOD limit of detection LOQ limit of
quantitation MU measurement uncertainty
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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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(No Transcript)
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PAH in precipitation at Kuhmo in 2007-2008
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Total PAH -concentrations in precipitation at
Pallas, monthly samples in 2006, Data from IVL
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PAH in precipitation Data from southern Finland
EVO, (SYKE/VTT), May-September
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
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PM10 ng/m3 Total PAH B(a)P  spring
Kuhmo 1,1 0,1 2008
Virolahti 4,1 0,3 2007
gradient
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EXAMPLE PAH-compounds in PM10- samples at Kuhmo,
Selected days in spring 2008
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3.3 2008
7.3 2008
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7.4 2008
14.3 2008
13.3 2008
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10.3 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-analysis LOQ (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!