what features of bushfire smoke should be considered in ... reisen, what... · ozone concentrations...
Post on 18-Oct-2020
3 Views
Preview:
TRANSCRIPT
What features of bushfire smoke should be considered in the assessment of public health risk?
CSIRO OCEANS AND ATMOSPHERE FLAGSHIP
Fabienne Reisen| Senior Research Scientist
Australia & New Zealand Aerosol Workshop, Wellington, 10-11 July 2014
Features that influence smoke exposure
1. Fire and fuel characteristics
Features of bushfire smoke & public health risk | Fabienne Reisen2 |
3. Pollutants
2. Smoke plume distribution near populated areas
Fire characteristics – Type, size, intensity
Features of bushfire smoke & public health risk | Fabienne Reisen3 |
Fires in savannas (grassland) are less intense and have short duration
Fires in eucalypt forest range from surface to crown fires with varying intensitiesPeat lands possess high fuel
loads and can burn over extended periods of time
Fires 06/07 Fires 07/08 Burns
Nu
mb
er
of
da
ys
0
10
20
30
40
Fires 06/07 Fires 07/08 Burns
Nu
mb
er
of
ho
urs
0
200
400
600
800
0-10 g/m3
10-25 g/m3
25-50 g/m3
>50 g/m3
0-10 g/m3
10-25 g/m3
25-50 g/m3
50-75 g/m3
75-100 g/m3
>100 g/m3
Smoke events in Northeast VIC (2006-2008)
Features of bushfire smoke & public health risk | Fabienne Reisen4 |
Prescribed burns Wildfires
Duration 3-48 hrs (average of 15 hours) 69 days
Intensity PM2.5: 2-30 fold increase
Max hourly PM2.5: 39-377 mg/m3
Max daily PM2.5: 540 mg/m3
Max hourly PM2.5: 1780 mg/m3
Combustion process
Ignition Flaming Smouldering Extinction
Features of bushfire smoke & public health risk | Fabienne Reisen5 |
Oxygen supply
Heat transfer
Fuel characteristics (size, structure,
moisture)
Flammable mixture of tar & gas products
CO2 and H20VOCs, NOx, N2O
EC or BC
CO, CH4
NMOC, NH3
PM
)COCO(
COMCE
2
2
Emission factors (g/kg) for species emitted
Tropical forest Savanna Boreal forest Temperate forest
CO2 1643 ± 58 1686 ± 38 1489 ± 121 1637 ± 71
CO 93 ± 27 63 ± 17 127 ± 45 89 ± 32
CH4 5.1 ± 2.0 1.9 ± 0.9 6.0 ± 3.1 3.9 ± 2.4
N2O 0.41 0.16 ± 0.21
PM2.5 9.1 ± 3.5 7.2 ± 3.4 15.3 ± 5.9 12.7 ± 7.5
PM10 18.5 ± 4.1
BC 0.52 ± 0.28 0.37 ± 0.20
OC 4.7 ± 2.7 2.6 ± 1.2
Features of bushfire smoke & public health risk | Fabienne Reisen6 |
Adapted from Agaki et al (2011) Emission factors for open and domestic biomass burning for use inatmospheric models , Atmos. Chem. Phys., 11, 4039-4072.
Emissions measurements
Laboratory studies – Controlled conditions
– Detailed studies of chemistry
– BUT: assume that fire properties in the lab represent combustion properties in the field
Field studies – ground level sampling– Sample real fires in undisturbed fuel beds
– BUT: issue of heterogeneity of smoke
Aircraft plume sampling– No heterogeneity of smoke
– BUT: expensive, complex and requires extensive plumes; need to take into account ageing of the plume
Features of bushfire smoke & public health risk | Fabienne Reisen7 |
Ground level sampling at prescribed burns
Features of bushfire smoke & public health risk | Fabienne Reisen8 |
Flaming combustion of fine fuels
Smouldering combustion of coarse fuels
Controlled experiments in the field
Features of bushfire smoke & public health risk | Fabienne Reisen9 |
Experimental burning of pure samples of each fuel/size class
Laboratory studies
Features of bushfire smoke & public health risk | Fabienne Reisen10 |
Pyrotron – 25 m long fire-proof wind tunnel- heading/backing fires- fuel/size class
Working section1.5 m wide and 4.8 m long
Emission factors
Features of bushfire smoke & public health risk | Fabienne Reisen11 |
Volkova et al. (2014) Fuel reduction burning mitigates wildfire effects on forest carbon and greenhouse gas emission, IJWF.
Fuel load and fuel moisture used to determine MCEMCE used to determine EFs
PM2.5 measurements
Features of bushfire smoke & public health risk | Fabienne Reisen12 |
Leaf litter burn more slowly and produces more smoke
with lower MCE
Well-aerated grass burns fiercely and efficiently
Feature of bushfire smoke - Emission source
Much of the variation in combustion products between fires is due to the way the fuel burns rather than the composition of the fuel
Combustion properties are critical to determine emission characteristics and are driven by fuel characteristics
Features of bushfire smoke & public health risk | Fabienne Reisen13 |
Smoke plumes and exposures
Features of bushfire smoke & public health risk | Fabienne Reisen14 |
Fresh smoke plumeComplex mixture of toxic air contaminants (gases & particles)
CO, PM, VOCs and SVOCs, NOY, Hg
Smoke dispersion and dilution
Atmospheric reactions
Aged smoke plumeOzone formed by photochemical reactionsSecondary organic aerosolsCO, fine particles
Thick smoke (limited photochemistry)
11/12/06 18/12/06 25/12/06 1/01/07 8/01/07 15/01/07
PM
2.5 c
on
cen
trat
ion
[
g/m
3 ]
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Hourly PM2.5
(Max hourly PM2.5 = 1.8 mg/m3)
Daily PM2.5
(Max daily PM2.5 = 1.1 mg/m3)
Victorian Alpine fires 2006/07
Features of bushfire smoke & public health risk | Fabienne Reisen15 |
• Fires started by lightning on Dec 1, 2006
• Area burned: 1,048,238 hectares
• Duration: 69-days
0
20
40
60
80
100
120
140
Nov-05 Dec-05 Mar-06 Apr-06 Jun-06 Aug-06 Oct-06 Dec-06
part
icul
ate
mas
s co
ncen
trat
ion
(ug
m-3
)
Bushfire season
2005/2006
Bushfire season
2006/2007
Melbourne (~200km from fires)
Ozone concentrations in smoke plumes
Features of bushfire smoke & public health risk | Fabienne Reisen16 |
Victorian Alpine fires 2006/07
• Photochemical formation of ozone in smoke trapped in valley
• Max hourly O3 = 150 ppb
• Max hourly PM2.5 = 1893 g/m3
Burn ~ 60 km from Manjimup (WA)
• Photochemical formation of ozone in smoke plume
• Elevated PM2.5 concentrations for 7-9 hrs
• Max hourly O3 = 65.2 ppb
• Max hourly PM2.5 = 227 g/m3
Reisen et al. (2011), Atmos Environ, 45, 3944
Southern California wildfires 2003 (Phuleria et al. (2005) J Geophys Res 110, D07S20)
• Limited photochemistry due to thick smoke
• Hourly O3 decreased from 29 ppb to 15 ppb
Features of bushfire smoke & public health risk | Fabienne Reisen
What pollutants should we consider?
17 |
Particle levels during wildfire events
Location Max hourly
PM [g/m3]
Max daily
PM [g/m3]
Duration
Southern CA (2003) 769 (PM10) ~ 400 (PM10) 7 days
Montana (2000) 340 (PM2.5) > 30 days
British Columbia (2003) 200 (PM2.5)
250 (PM10)> 30 days
Portugal (2003) 500 (PM10)
Northern CA (1999) > 1000 (PM10) > 500 (PM10)
Indonesia (1997) 1800 (PM10)
Sydney (1994) 250 (PM10) 210 (PM10) 8 days
Victorian Alpine fires (2006/07)
Melbourne
1800 (PM2.5) 1100 (PM2.5)
~ 120 (PM2.5)
69 days
Features of bushfire smoke & public health risk | Fabienne Reisen18 |
Chemical composition of particles
• ToF- Aerosol Chemical Speciation Monitor
• Unit mass resolution, no sizing
Features of bushfire smoke & public health risk | Fabienne Reisen19 |
`
Particle Inlet (1 atm)
Thermal Vaporization &
Electron Impact
Ionization
Aerodynamic Lens40-1000 nm
eTOFMass Spec
Particle Composition
Gunn Point – Savanna fire season
Features of bushfire smoke & public health risk | Fabienne Reisen20 |
expect to see ~ 80-90% of PM1 through ACSM lens
Deconvolution of mass spectra into component spectra
• HOA – Hydrocarbon-like organic aerosol
• OOA – Oxidized organic aerosol
• BBOA – Biomass burning organic aerosol
• COA – Cooking organic aerosol
PMF analysis applied to ACSM data sets
Features of bushfire smoke & public health risk | Fabienne Reisen21 |
Summary
Combustion and fuel characteristics influence smoke production and composition
Emission factors are critical to determine amount of toxic compounds released into the atmosphere
Plume distribution is affected by meteorological conditions and topography
The main hazardous component for public health is fine particulate matter (size and composition)
Impact of other pollutants (e.g. mercury, VOCs) on public health is uncertain
Features of bushfire smoke & public health risk | Fabienne Reisen22 |
CSIRO Oceans and Atmosphere FlagshipFabienne ReisenSenior Research Scientist
t +61 3 9239 4435e fabienne.reisen@csiro.au
OCEANS & ATMOSPHERE FLAGSHIP
Thank you
Size distribution of bushfire smoke particles
Features of bushfire smoke & public health risk | Fabienne Reisen24 |
1.E+02
1.E+03
1.E+04
1.E+05
10 100 1000diameter (nm)
dN
/dlo
g10D
(cm
-3)
bushfire influenced
reference
0
20
40
60
80
100
120
140
10 100 1000 10000 100000diameter (nm)
bushfir
e m
ass c
oncentr
atio
n
(µgm
-3)
0
2
4
6
8
10
12
14
16
18
20
refe
rence m
ass
concentr
atio
n (
µgm
-3)
bushfire influencedreference
Number distributions on a bushfire day and on a day without strong smoke impact
24-hour MOUDI distributions on two bushfire days and two days without strong smoke impact
top related