Chemical speciation of PM and mass closure

David Green, Gary Fuller & Anja Tremper

King’s College London

2

ContentsLondon sampling campaigns

Methodology

Use of uncertainty

Results

Source apportionment – London and Paris

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Sampling campaignsSummer campaign

• Aug-Oct 2008• Brent & Tower Hamlets

Winter 2008 campaign• Nov-Dec 2008• Camden, Brent & Tower

Hamlets

Further Camden campaigns

• May - June 2010• PM10 and PM2.5

• Summer 2010• Further PM10• Construction and another

roadside

Brent - Ikea

Tower Hamlets – Blackwall Tunnel

Camden – Swiss Cottage

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Methodology

Pragmatic mass closure

2 Partisols• 1 Teflon – Mass, IC, ICP-MS• 1 Quartz – EC/OC

ERG mass closure

Existing TfL monitoring sites• TEOM / FDMS• Aethalometer (EC)

Sampled onto alternate filters on different days

• Mixed cellulose esters – ICP-MS• Quartz – EC/OC• Longer time period• Used one sampler

Existing Defra monitoring at North Ken and Marylebone Road for concentrations of regional pollutants when not measured directly

• IC and EC/OC• Nitrates, Sulphates, Chlorides, SOA

Aethalometer measurements for EC and POA using site specific empirical relationships

Results in time series composed of two datasets

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Methodology

MassFDMS – direct massTEOM – used Volatile Correction Model (VCM)

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Methodology Elemental CarbonDataset A

• Aethalometer using Xgenline empirical relationship

• Uncertainty included

Dataset B• Sunset

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Methodology Primary Organic CarbonEC tracer measurement used to split SOA and POA

• Evidence of organic gas adsorption onto filters

• Intercept and slope derived using min 5% of EC/OC ratios

Factor for organic mass of 1.4 used (Japar, 1984) from direct measurements of diesel emissions

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Methodology Secondary Organic CarbonEC tracer measurement used to split SOA and POA

• SOA = OC - (EC/OC)prim x EC• Evidence of organic gas adsorption onto

filters• Intercept and slope derived using min 5% of

EC/OC ratios• Factor for organic mass of 2.1 used (Turpin

and Lim, 2001), recommended for non-urban aerosol

Good agreement between sites• Dataset A mean of available measurements

in London direct• Dataset B Sunset analysis• Variation included in uncertainty calculation

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Methodology Nitrates, sulphates & chloridesMeasurements from mean of Marylebone and North Kensington usedFactors applied to account for cationsNitrate can be ammonium or sodium

• Masses similar (18 or 23)• Harrison (2003) found 60% NH4NO3

• Applied a factor of 1.32 (60% NH4NO3 and 40% NaNO3)

Sulphate• Applied factor of 1.19

Chloride• Applied factor of 1.65

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Methodology WaterUsed Aerosol Inorganic Model (AIM)

• Used nitrate and sulphate measurements as inputs

• Used FDMS sampling conditions of 30% RH and 30ºC

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Methodology Iron Rich DustSplit into Minerals, Iron Oxide and MetalsMeasured wide range of metals (Fe, Ca, Al, Ba, Cu, Mo, Mn, Ni, Pb, Sb, Sr, V and Zn)Used Al as a tracer for feldspars (e.g. KAlSi3O8)

• Applied factor of 8.4• Included uncertainty in this factor

Ca used as a tracer for calcite and gypsum

• Applied factor of 3.8• Included uncertainty in this factor

These grouped together as mineralsFe used as a tracer for an iron oxide (FeO, Fe2O3 or Fe3O4)

• Applied factor of 1.37• Included uncertainty in this factor

Other metals included as ‘raw’ massOn days when ICP-MS not undertaken (dataset B) difference between PM10 mass and available components used to assess this

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Alternate filters

Component Dataset A Dataset B

EC Aethalometer

Sunset

POA Aethalometer

Sunset

SOA Regional Sunset

Nitrates Regional IC

Sulphates Regional IC

Chlorides Regional IC

Water AIM AIMMinerals / unidentified

ICP-MS Difference

A

B

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Site Variability

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Daily Variability

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Uncertainty analysis

Guide to uncertainty in measurement methodology (GUM)

Simple…

Measurement equation• TEOMVCM = TEOM – (ƒVCM x FDMS purge) – FDMS purge

Uncertainty equation• UVCM = 2 x √(uTEOM)2 + (uƒVCM x FDMS purge)2 + (ƒVCM x uFDMS purge)2

Complex…

Total Mass• uTotalMassA = 2x √(uECa

2 + uPOAMa2 + uSOAMregional

2 + uNO3total2 + uSO4total2 + uCltotal

2 + uWater2 + uMinerals2 + uIronOxide2 + uMetals2)

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Validation against PM10Tower Hamlets

4Brent 4Camden 1

y = 0.91 (±0.05) x+ 2.19 (±1.91)

r2 =0.84

y = 1.11 (±0.07) x+ -3.88 (±2.26)

r2 =0.82

y = 0.87 (±0.11) x+ 6.9 (±3.22)

r2 =0.58

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Analysis outputs - Comparison to source apportionment

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Dataset Date

PM10

(µg

m-3)

EC (µ

g m

-3)

POA

M (µ

g m

-3)

SOA

M (µ

g m

-3)

Nitr

ate

(µg

m-3

)

Sulp

hate

(µg

m-3

)

Chl

orid

e (µ

g m

-3)

Wat

er (µ

g m

-3)

Min

eral

s (µ

g m

-3)

Iron

Oxi

de (µ

g m

-3)

Oth

er m

etal

s (µ

g m

-3)

Uni

dent

ified

(µg

m-3

)

Tota

l (µg

m-3)

Epis

ode

driv

er(s

)

Bre

nt

Dat

aset

A

04/11/08 56.3 12.3 3.9 5.5 16.7 11.6 5.4 0.0 7.3 2.6 0.3 -9.4 65.7 S

20/09/08 52.0 13.6 4.3 3.8 9.0 3.0 2.5 2.0 9.9 3.7 0.4 -0.3 52.3 PSM

26/09/08 51.0 12.3 3.9 5.9 9.7 5.5 4.3 1.4 9.1 3.5 0.4 -4.9 55.9 SM

16/12/08 50.1 10.1 3.2 6.0 5.0 2.3 1.7 1.0 2.2 2.4 0.2 16.0 34.1 N

Mean 29.4 6.7 2.1 3.2 4.2 2.4 3.4 0.7 3.9 1.9 0.2 0.7 28.7

Bre

nt

Dat

aset

B

30/08/08 57.5 6.0 1.9 6.5 18.8 8.2 3.1 3.9 - - - 9.1 48.4 S

17/09/08 53.3 11.2 3.5 3.4 9.0 2.9 3.1 2.0 - - - 18.1 35.1 M

27/09/08 58.7 10.1 3.2 8.3 16.2 6.0 1.8 3.5 - - - 9.5 49.1 S

07/12/08 56.8 14.2 4.5 10.0 12.0 2.0 4.9 3.1 - - - 6.1 50.7 PS

Mean 28.1 6.7 2.1 3.0 4.5 2.3 3.5 0.9 - - - 5.1 23.0

Tow

er H

amle

ts

Dat

aset

A

31/08/08 61.5 6.1 4.6 7.1 26.6 6.5 4.7 6.5 2.3 1.6 0.2 -4.7 66.2 S

22/09/08 65.4 8.2 6.2 2.7 5.3 2.3 3.0 1.1 12.2 3.3 0.4 20.6 44.8 N

04/11/08 57.1 4.6 3.5 5.5 16.7 11.6 5.4 0.0 9.2 1.7 0.4 -1.5 58.6 S

06/11/08 69.5 9.7 7.3 7.9 6.2 5.2 1.0 0.0 18.8 4.0 0.6 8.8 60.7 SM

10/12/08 64.6 6.9 5.2 6.5 5.7 1.1 4.0 1.5 18.7 4.4 0.4 10.2 54.3 M

16/12/08 58.6 8.5 6.5 6.0 5.0 2.3 1.7 1.0 9.9 3.5 0.4 13.8 44.8 N

Mean 33.1 5.2 3.9 3.4 4.4 2.2 3.5 0.8 6.5 2.3 0.3 0.7 32.5

Tow

er H

amle

ts

Dat

aset

B

30/08/08 54.0 1.8 1.3 7.3 18.8 8.2 3.1 3.9 - - - 9.5 54.0 S

19/09/08 53.7 6.9 5.2 6.6 6.8 2.8 3.6 1.4 - - - 20.3 53.7 N

05/11/08 69.2 7.9 6.0 9.3 5.5 5.8 0.7 0.0 - - - 34.1 69.2 SM

07/12/08 56.1 8.2 6.2 13.8 12.0 2.0 4.9 3.1 - - - 5.9 56.1 S

11/12/08 60.2 9.8 7.4 6.5 11.4 2.1 5.3 2.9 - - - 14.8 60.2 S

17/12/08 52.3 8.3 6.2 7.7 3.3 1.3 4.3 0.7 - - - 20.5 52.3 S

Mean 34.2 4.9 3.7 3.5 4.7 2.2 3.4 0.9 - - - 10.8 34.2

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Next steps and improvements…

Organic absorption onto quartz filters• Quartz back quartz study to assess adsorption in next 2 months

Efficiency of aqua regia digest for extracting Al• HF digest

ICP-MS for Ca and Al• Comparisons with ICP-AES

Al as a tracer for Si• XRF analysis

How representative is one location to another• More direct measurements

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Acknowledgements

London Borough of Camden

Transport for London

Source apportionment of PM10 in London and Paris-intial results

Gary Fuller and Anna Font Font King’s College

LondonMarch 2010

Centre for Environment and Health

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Relationship between annual mean PM10 and NOX in London Fuller et al., (2002), Fuller and Green (2006)

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Relationship between annual mean PM10 and NOX in Paris

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Primary PM10 : NOX ratio London and ParisProgressive Euro classes preferentially abate PM10 over NOX then grad should

be decreasing!Effects of London specific PM measures?

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Non-primary PM10 London and ParisNon primary PM10 converging

Paris did not experience 2006 elevation seen in London