Black carbon and elemental carbon as
possible regulated metrics
Paul Quincey
Dispersion Modellers User Group
5 December 2012
Talk outline
1. Soot concentration as a measure of air quality
2. The role of soot in climate change
3. Ways to measure soot concentration, including
black carbon and elemental carbon
4. Defra network measurements of black carbon
and elemental carbon
5. A possible regulated metric?
Soot and air quality
“The barking and the spitting is uncessant, and the
inhabitants of London find it in all their
expectorations; the spittle, and other excrements
which proceed from them, being for the most part of
a blackish and fuliginous colour”
John Evelyn, 1661
1950s smog
1956 Clean Air Act
Smoke – soot particles,
with various molecules on
their surface
Measured as “Black Smoke”
(+ sulphur
dioxide)
Figure 2.1: Schematic diagram of the size distribution of airborne particles
condensation of
hot vapour
Particles in
ambient air
chemical route to
low volatility compound
mechanical generation
homogeneous
nucleation
wind blown dust
sea spray
volcanic particles
condensation
growth
primary
particles
1.6
1.4
coagulation growth
sedimentation
rainout/washout
0.4
0.3
0.001
0.01
0.1
2.2
transient nuclei
2.3
particle diameter
accumulation
mode
PM2.5
1.0
10
100
(micrometres)
coarse mode
PM2.5-10
Iron rich dust
From AQEG (2005)
Calcium sulphate
Sodium chloride
Ammonium nitrate
(Fine particles at urban
Ammonium sulphate
3.9
3.1
Organic compounds
Elemental carbon
Bound water
5
background sites)
Is soot relevant for health effects?
- Yes
Is soot relevant for health effects?
- yes
Is it the only
relevant metric
for health effects
– no
Cloud
formation
due to
aerosol
from ships
http://earthobservatory.nasa.gov
Central Washington University
Black
carbon on
snow
Aerosol
direct effect:
absorption
and
reflection by
particles in
the
atmosphere
2011 UNEP & WMO report
“Black carbon and ozone in
the lower atmosphere are
harmful air pollutants that
have substantial regional and
global climate impacts.”
Soot is a primary pollutant
The decline of sulphur dioxide and “black smoke” 1962-1996
• 2011 Marylebone Road / Harwell ratio of
PM10
~ 2.5 [35 vs 14 μg.m-3]
Black Carbon
~ 20
• Berlin LEZ developments
[10.3 vs 0.5 μg.m-3]
May 2012 –
Gothenburg Protocol revision
“The Gothenburg Protocol will be updated setting more ambitious targets to
reduce trans-boundary air pollution. In particular, the revised objectives of
the Protocol will see a reduction in EU emissions of around 60% for sulphur,
40% for nitrogen oxides (NOx), 30% for volatile organic compounds (VOCs),
6% for ammonia and 20% for particulate matter compared to 2005 levels. A
paper recently published by the European Commission indicated that a limited
number of air quality measures can substantially mitigate global warming.
As announced in a joint statement by the Danish EU Presidency and Janez
Potočnik, European Commissioner for the Environment, the Gothenburg
Protocol will be updated having for the first time, an international agreement
that acknowledges the link between air pollution and climate change. In
addition, there is an agreement to act on so called 'Black Carbon', a
pollutant with short-lived climate forcing characteristics.”
Measuring soot concentration
(selected)
Principle
Optical properties of filter
samples
Instrument type
White light reflectance
Term used
Black smoke
Single or multiBlack carbon
wavelength transmittance
(aethalometer)
Multi-angle reflectance
and transmittance
(MAAP)
Black carbon
Instrument example - aethalometer
Absorption of specific wavelengths by collected particles :
880 nm (near-ir) and 370 nm (near-uv)
High precision and time resolution
Real time data
- but needs “loading” correction
Measuring soot concentration
(selected)
Principle
Optical properties of filter
samples
Instrument type
White light reflectance
Term used
Black smoke
Single or multiBlack carbon
wavelength transmittance
(aethalometer)
Optical absorption of
airborne samples
Multi-angle reflectance
and transmittance
(MAAP)
Black carbon
Photo-acoustic
Black carbon
Laser induced
incandescence
Black carbon, refractory
carbon
Chemical analysis of filter Thermo-optical (eg
samples by thermal
Sunset)
decomposition with
charring correction
Elemental carbon
(measured together with
organic carbon)
Manual Carbon Results Screen
Furnace
methaniser and FID
Organic and elemental carbon
Temp
• metals (Ni, As, Cd, Pb, Hg, V, Cr, Mn, Fe, Cu, Zn,
Pt)
He
O2
by ICP-MS
• sulphate, nitrate and chloride analysis by ion
chromatography
OC/EC
Carbon
Filter
dividing
line22(OC/EC)
•
organic
/ elemental
carbon
Friday,
07 December
released
darkness
2012
Green
Magenta
Blue
Red
Grey
FID Response (Amount of Carbon)
Attenuated FID Response
Oven Temperature
Amount of transmitted light
Absorbance of sampler
Several
EC/OC
analysis
methods
exist –
these are
currently
being
standardised
Emission source
Glasgow Urban Area
Birmingham Urban Area
Birmingham Urban Area + London Urban Area
London Urban Area
Solid Fuel Use
Possible Solid Fuel Use
Domestic Emissions
Defra’s Black
Carbon Network
2-wavelength
aethalometers
Hourly data
Key
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Site Name
Glasgow Kerbside
Glasgow Centre
Auchencorth Moss
Birmingham Tyburn Roadside
Birmingham Tyburn Background
Harwell
North Kensington
Marylebone Road
Detling
Belfast centre
Lisburn Dunmurry
Strabane
Norwich Lakenfields
Cardiff 12
2010 periodicity data – Marylebone Road
2010 periodicity data – Strabane
2010 periodicity data – Harwell
Defra Particles Network
SITE
HOURLY
PM10
ANIONS/CATIONS
WEEKLY
PM2.5
OCEC
DAILY
PM10
OCEC
Birmingham
Tyburn
(Urban
Background)
CPC
SMPS
AETHALOMETER
X
X
Harwell
(Rural)
X
X
X
X
North Kensington
(Urban
Background)
X
X
X
X
Marylebone Road
(Roadsite)
X
X
X
X
Auchencorth
Moss
X
EC/OC: EUSAAR II and Quartz protocols
comparison
Elemental carbon vs black carbon (urban)
concentration / g m
-3
concentration / g m
20
15
10
5
North Ken EC
North Ken BC
12
-3
Marylebone EC
Marylebone BC
25
10
8
6
4
2
0
0
Marylebone Road
Linear fit
North Kensington
Linear fit
10
20
15
3
BC (g/m )
3
BC (g/m )
8
10
y = 1.2603 x + 0.4068
2
R = 0.9459
6
y = 1.1619 x + 0.0288
2
R = 0.7339
4
5
2
0
0
0
5
10
15
3
EC (g/m )
20
25
0
2
4
6
8
3
EC (g/m )
10
12
01/12/2010
01/11/2010
01/10/2010
01/09/2010
01/08/2010
01/07/2010
01/06/2010
01/05/2010
01/04/2010
01/03/2010
01/02/2010
01/01/2010
01/12/2010
01/11/2010
01/10/2010
01/09/2010
01/08/2010
01/07/2010
01/06/2010
01/05/2010
01/04/2010
01/03/2010
01/02/2010
01/01/2010
12
25
Elemental carbon vs black carbon (rural)
Harwell EC
Harwell BC
concentration / g m
-3
2.5
2.0
1.5
1.0
0.5
0.0
3
BC (g/m )
1.5
y = 0.8858 x + 0.203
2
R = 0.5546
1.0
0.5
0.0
0.0
0.5
1.0
1.5
3
EC (g/m )
2.0
2.5
01/12/2010
Harwell
Linear fit
2.0
01/11/2010
01/10/2010
01/09/2010
01/08/2010
01/07/2010
01/06/2010
01/05/2010
01/04/2010
01/03/2010
01/02/2010
01/01/2010
2.5
A possible regulated metric?
Soot concentration is a very useful Air Quality
measure, with additional benefits for Climate
Change.
The measure to be used needs careful choice
and standardisation.
There would be cost implications if the
measure became regulated without reduction in
other requirements.
Thank you
[email protected]