An application of physics: An application of physics: sampling and analysing air particulate mattersampling and analysing air particulate matter

GNS Science, PO Box 31312, Lower Hutt, New ZealandGNS Science, PO Box 31312, Lower Hutt, New Zealand

Bill Trompetter, Perry Davy, Bernard Barry and Andreas MarkwitzBill Trompetter, Perry Davy, Bernard Barry and Andreas Markwitz

GNS Science

• New Zealand has good air quality in general

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Masterton DunedinAuckland

PM10 2004-2007 at Masterton

• However, air pollution does occur in NZ• Some smaller towns have the highest levels of air pollution• PM10 has strong peaks in winter due to domestic biomass burning

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Particle size comparison

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Atmospheric particles: size and number distribution

• Two distinct size modes, coarse (PM10-2.5) & fine (PM2.5)

• Size range depend on method of source generation

• Coarse particles dominate mass profile

• Fine particles dominates number profile

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Atmospheric particles: health effects

• PM10 in NZ caused ~900 premature deaths and cost a total of NZ$1.3 billion in health costs and lost productivity in 2001 [Fisher 2007] .

• Symptoms range from subtle sub-clinical effects to respiratory and cardio-pulmonary disease

• NZ National Environment Standard was introduced in 2005 (50 g/m3 for PM10)

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Samplers – size selective inlets

Size-selective inlets define the particle size fraction sampled (Chow, 1995).

Direct impaction: • the impactor with specific dimensions.• small particles bend at the impaction plate• larger particles impact against the plate

Virtual impactor: • uses an opening• larger particles to one sampling substrate, • smaller particles follow the streamlines to another• ~10% of the total flow, drawn through the virtual impactor are collected with the coarse particles (corrections needed).

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GENT Sampler – stacked filter unit

http://www.nilu.no/products/

Air flow direction

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GENT Sampler – APM filters

Coarse (PM10-2.5) polycarbonate Nucleopore filter loaded with air particulate matter from the Wellington region.

Fine (PM2.5-0) polycarbonate Nucleopore filter loaded with air particulate matter from the Wellington region.

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Elemental analysis and source apportionment: Why?

Gravimetric mass ≠ source information

Masterton DunedinAuckland

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Source apportionment

Elemental concentrations in particulate matter are determined at the NZ Ion Beam Analysis facility at Gracefield, Wellington

Particle beam 1H+

RBS particle detector

Target filter

apertures

ion energy 2.5 MeV

X-ray detector 1

X-ray detector 2

135 o

X-ray filter 1

X-ray filter 2

45 o 135 o

-ray detector

PESA particle detector

45 o

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Zn Kb

Mg

CuNi

V

Ti

Sc

K

Al

MnZn

Na S

Cr

CaFe

"Seasalt" Au0609

"Soil" Au0532

"Industry" Au0534

"Smoke" Au0610

PIXE spectra from Lower Hutt PM2.5 filters

Cl

Fe Kb

Si

Co

un

ts

Energy (keV)

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100

1000

10000

100000Proton's scattered

from elements heavier than Hydrogen

Hydrogen "peak"

Energy (keV)

Cou

nts

Kowhai PM2.5 06/15758

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Black Carbon (BC)

For atmospheric particles, black carbon (soot) absorbs light very strongly (Horvath 1993, 1997). Hence, to first order it can be assumed that all the absorption on pollution filters is due to BC.

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Elemental relationships and source determination

Seaview PM10-2.0 Al vs Si

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Si (ng/m3)

Al (n

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Seaview

Baring Head PM10-2.0 Cl vs Na

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Baring Head

Plots show that elements are related to each other

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Initial source identification by principle components analysis: PM2.5 at Masterton

Element

Factor 1 Factor 2 Factor 3 Factor 4

Vehicles Soil Combustion Seasalt

BC 0.16 0.03 0.97 -0.08

Mg 0.02 0.97 0.09 0.03

Al 0.33 0.92 0.10 -0.05

Si 0.76 0.56 0.06 0.15

S 0.71 0.30 0.12 0.37

Cl 0.14 -0.06 -0.06 0.95

K 0.23 0.18 0.93 0.08

Ca 0.69 0.26 0.21 0.52

Fe 0.84 -0.08 0.35 -0.07

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Wood Burning

05

101520253035404550

Jun-02 Aug-02 Oct-02 Dec-02 Feb-03 Apr-03 Jun-03 Aug-03 Oct-03 Dec-03 Feb-04 Apr-04 Jun-04 Aug-04 Oct-04

Co

nc

en

tra

tio

n

g/m

3

Sulfate

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Motor Vehicles

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Jun-02 Aug-02 Oct-02 Dec-02 Feb-03 Apr-03 Jun-03 Aug-03 Oct-03 Dec-03 Feb-04 Apr-04 Jun-04 Aug-04 Oct-04

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Soil

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Seasalt

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Temporal variation in source contributions at Masterton

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Masterton PM10 : Average mass contribution to ambient particle concentrations by sources using positive matrix factorisation

Average source contributions to PM10-2.0 at Masterton

Seasalt40%

Soil26%

Wood Burning27%

Motor Vehicles7%

Average source contributions to PM2.0 at Masterton

Wood Burning72%

Motor Vehicles5%

Soil9%

Seasalt7%

Sulfate7%

PM10-2.5 PM2.5

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Source mass contributions to Masterton PM10

Masterton PM10-2.0 source contributions

11/07/2004 - 12/07/2004

Wood Burning

51%

Road Dust6%

Soil33%

Seasalt10%

Masterton PM2.0 source contributions

11/07/2004 - 12/07/2004

Soil4%

Seasalt2%

Sulfate3%

Wood Burning

91%

PM2.5 = 32 g/m3PM10-2.5 = 19 g/m3

Wood Burning

77%

Seasalt5%

Soil14%

Sulfate2%

Motor Vehicles

2%

Masterton 12 July 2004, high pollution day exceeded national environmental standard (PM10 = 51 g/m3 24 hour average)

PM10 = 51 g/m3

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Auckland (Kingsland) sulphate sources

Biomass burning

38%

Marine aerosol19%

Motor vehicles30%

Sulphate13%

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rin

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lPM

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g m

-3)

Directional studies (CPF) and mapping (PSCF) of the source apportionment results can add much more value for the end users.

GNS Science

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Hauraki Gulf shipping lanes and port area

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Directional (CPF) analysis of

sulphate sources

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Kingsland PM2.5 secondary sulphate sourcePSCF back trajectory analysis

• secondary sulphate source areas are oceanic due to phytoplankton.

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Regional sulphate ‘event’ – 28 September 2006

Sulphate - Kowhai PM2.5

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Sulphate - Takapuna PM10

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Sulphate - Khyber Pass PM2.5

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Sulphate - Penrose PM2.5

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White Island

Receptor modelling results for sulphate Air mass back-trajectory

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Kingsland PM2.5 marine aerosol sourcePSCF back trajectory analysis

• PSCF analysis results indicate that the PM2.5 marine aerosol source areas are southwest of NZ – southwesterly sweep over Southern Ocean

• Consistent with CPF (inset) analysis

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Marine aerosol

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Summary• Pollution has

– different size distributions – mix of natural and anthropogenic sources– collection methods

• Elemental analysis allows identification of APM sources and their contributions determined.– individual filter samples (1 day or 1 hour).– analysis by day, year, season, weekday, weekend … – information assists with air quality management.

• Directional analysis can provide addition information for:– local sources (CPF).– long range sources (PSCF).

An application of physics: An application of physics: sampling and analysing air particulate mattersampling and analysing air particulate matter