overview of epa activities and research related to black

Overview of EPA activities and research related to black carbon

Gayle Hagler, Ph.D.U.S. EPA Office of Research and DevelopmentNational Risk Management Research Laboratory

Disclaimer: The views here represent those of the author and not necessarily of the United States Government

ADDRESSING THE CHALLENGES OF BLACK CARBON IN RUSSIA A Joint U.S. National Academies – Russian Academy of Sciences WorkshopApril 1-10, 2015

Purpose

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The purpose of this international presentation is to give an overview of EPA activities related to black carbon (BC). This overview includes some summary information on how EPA defines BC, current knowledge on United States emissions and forecasted emission reductions, and ongoing research regarding measurement methodology, emissions characterization, and near-source research.

Outline

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• US EPA interest in black carbon emissions and impacts

• Black carbon emissions in the United States – past and future

• Ongoing EPA research related to black carbon

• Measurement methods• Emissions characterization• Near-source air quality impacts

Defining BC

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“Black carbon (BC) is a solid form of mostly pure carbon that absorbs solid radiation (light) at all wavelengths. BC is the most effective form of PM, by mass, at absorbing solar energy, and is produced by incomplete combustion.”

Interest in BC

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• Health effects:• BC is an important component of PM2.5• Indicator of localized air pollution

impacts: elevated levels have been observed in close proximity to transportation sources

• Climate impacts• Direct effect through absorption of solar

radiation in the air, or deposited to snow/ice

• Indirect effect on cloud properties• Mitigation of BC as complementary and

providing increased effectiveness, than reduction in CO2 emissions alone, due to its short atmospheric residence time.

Climate and BC

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Source: Bond et al. (2013)

United States Emissions

• In the US, there is estimated, in 2005, to be about 0.64 tons of BC emitted by all sources.

• Globally, about 8.4 million tons of BC is emitted.• Distribution of sources in US is different than globally for BC.• In the US, BC emissions, generally, are derived from PM2.5 emission

inventories, via use of speciation factors.

United States Emissions

• Organic carbon (OC) always co-emitted with BC, must be considered in any control and/or mitigation scenarios.

• Most of OC comes from open burning, and is considered to be reflective (cooling).

• How much of OC is light-absorbing (warming brown carbon, BrC)?

U.S. mobile sources

• U.S. mobile source BC comes mainly from diesels

• Gasoline exhaust is a smaller source of BC

U.S. Black Carbon Emissions from all Mobile Source Categories, 2005(total 333,400 tons)

U.S. mobile sources

BC emissions from U.S. mobile sources controlled by:

• Emissions standards for new engines• Requirements for diesel particulate filters (DPFs) in conjunction with ultra

low sulfur diesel (ULSD) fuel• Gasoline vehicle volatile organic compounds (VOCs, and other gaseous

pollutants) standards also reduce PM emissions• Standards for PM are “technology forcing.”• Reductions estimated from emissions models used in regulations

• On road BC, OC, PM inventory from MOVES (Motor Vehicle Emission Simulator) model

• Nonroad BC inventory from NONROAD model• Locomotive, marine, and aircraft emissions estimated by separate

models• Retrofit programs for in-use mobile diesel engines, such as EPA’s National Clean

Diesel Campaign and the SmartWay Transport Partnership Program

U.S. mobile sources

• On-road diesel PM standards – 2007 model year• 99% reduction in diesel PM for 2012 diesel trucks compared

to 1970 pre-control diesel trucks• On-road diesel PM and BC reduced by 91% and 95%

respectively from 2005-2030• Diesel particulate filters preferentially reduce BC• Earlier diesel PM standards also reduced BC• Fleet turnover needed to achieve full PM/BC reductions

• Standards for non-road diesels started in 2012• Standards for locomotives and commercial marine (categories 1

and 2 but not ocean going)

U.S. mobile sources

Total U.S. mobile source BC emissions are projected to decline by 86% by 2030 due to regulations already promulgated.

Emissions from U.S. Mobile Sources

EPA Research: Methods

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Ambient comparisons of elemental carbon (EC) and BC often show fairly good agreement, although there are some exceptions.

70% of Studies

Source: EPA Report to Congress on Black Carbon


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• Elemental carbon is commonly measured in US ambient networks and emission factors, using operationally defined thermal/optical transmittance (TOT) or thermal/optical reflectance (TOR) methods

Time (seconds)

0 150 300 450 600

FID

sig

nal

0

200

400

600

800

1000

Tem

pera

ture

(oC

)

0

250

500

750

1000

Lase

r sig

nal

0

500

1000

1500

2000He/O2He

λ= 632.8 nm

Organic carbon Elemental carbon

Flame ionization dector(FID)


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EPA study comparing multiple EC measurement protocols for duplicate samples: some agree closely, others show some disagreement.IMPROVE: Interagency Monitoring of Protected Visual EnvironmentsNIOSH: National Institute of Occupational Safety and HealthNIST: National Institute of Standards and Technology

[p = 0.0690]

[p = 0.1724]

[p = 0.0391]

[p = 0.0091]

[p = 0.3024]

[p = 0.3165]

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

NIST TOTNIST TOR

NIOSH TOTNIOSH TOR

IMPROVE TOTIMPROVE TOR

Cookstove

Diesel

Rural

Urban

EC/TC ratio

NIST TOTNIST TOR

NIOSH TOTNIOSH TOR


NIST TOTNIST TOR

NIOSH TOTNIOSH TOR


NIST TOTNIST TOR

NIOSH TOTNIOSH TOR


TOR

TOTAverage location

(0.34)(0.43)

(0.34)(0.41)

(0.39)(0.50)

(0.48)

(0.51)

(0.07)

(0.07)(0.13)

(0.16)

(0.27)(0.29)

(0.26)(0.28)

(0.38)(0.33)

Average value( )P value (α = 0.05)

[p = 0.0175]

[ ]

[p = 0.3307]

[p = 0.2010]

[p = 0.0001]

[p = 0.0001]

[p = 0.0001]

(0.52)

(0.55)(0.70)

(0.75)

(0.14)

(0.08)

Khan et al., 2012, AST *TC = total carbon


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Comparison of multiple BC instruments against thermal-optical EC for different source emissions

Holder et al., in preparation


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Keen interest in high-time resolution measurements for dynamic monitoring environments

Dynamic emissions Isolating clustered sources Mobile monitoring

- Optical measurements (filter-based, photoacoustic, laser-induced incandescence) currently provide highest time resolution


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Optimized noise-reduction algorithm (ONA) developed to maximize time resolution in filter-based continuous measurement (aethelometry)

18:00 00:00 06:00 12:00-2000

0

2000

4000

6000

8000

10000

12000

14000

aver

age

BC c

once

ntra

tion

(ng

m-3)

AE51 – 60 s data29% negative

Indoor air

09:00 12:00 15:00-1

-0.5

0

0.5

1

1.5

2x 10

5

time

aver

age

BC

con

cent

ratio

n (n

g m

-3)

AE51 - 1 s data32% negative

Cookstove emissions

07:00 07:30 08:00 08:30 09:00-5

0

5

10x 10

4

time

aver

age

BC

con

cent

ratio

n (n

g m

-3)

On-road sampling AE42 – 1 s data13.3% negative

Hagler et al., 2012, AAQR


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Optimized noise-reduction algorithm (ONA) developed to maximize time resolution in filter-based continuous measurement (aethelometry)

Hagler et al., 2012, AAQR

18:00 00:00 06:00 12:00

0

5000

10000

15000

20000

time

aver

age

BC

con

cent

ratio

n (n

g m

-3)

originalAETH-ATNavg

18:00 00:00 06:00 12:000

20

40

60

80

100

120

140

time

# pt

s av

erag

ed

Reduction of negative values from 29% to ~0%, while retaining peak

Variable averaging window set by the incremental light attenuation output by aethelometers

EPA Research: Emission Studies

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Ongoing field and laboratory research characterizing emissions, and updating emission factors in inventory, including:- Prescribed burns and wildfires (Brian Gullett, Amara Holder)- Aircraft emissions (John Kinsey)- Vehicle emissions – light and heavy-duty dynamometer (Rich Baldauf,

Tom Long)- Stationary source emissions (Tiffany Yelverton, Amara Holder)- Cookstoves (Jim Jetter, Amara Holder)

Diesel genset Open burning test facility

Pilot scale coal power pant


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Emissions studies characterizing BC:

Black carbon size distribution by source

Holder et al., in preparation

Laser-induced incandescence


Emissions studies quantifying BC: Holder et al., in preparation

Abs

orpt

ion

angs

trom

exp

onen

t (A

AE)

EPA Research: Emission StudiesProject lead: Brian Gullett

300

350

400

450

500

550

600

0.0

0.5

1.0

1.5

2.0

2.5

16:53 17:33 18:13 18:53 19:33

CO2

(ppm

)

PM2.

5an

d BC

(mg/

m3 )

PM2.5

Black Carbon

CO2

In situ sampling with AeroStat: integrated and real-time measurements

Image: aethlabs.com

EPA Research: Near-Source

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R2PIER project: Combining high-time resolution stationary sampling, with inverse local back trajectory modeling, to look at emission area changes with time.

Monitoring: ~1.5 million BC data points (1-minute data, 3 years)

Port

Airport

Port

EPA leads: Gayle HaglerDan Birkett


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R2PIER study: example results for one month of the study

Monitoring: ~1.5 million BC data points (1-minute data, 3 years)

Port

Airport

Port

EPA leads: Gayle Hagler, Dan Birkett


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Ongoing research on BC and co-emitted pollutant concentrations near highways, rail yards, ports; mitigation strategies

Example: Cicero Rail Yard Study (EPA Region 5 study)EPA ORD lead: Gayle Hagler


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Example: Cicero Rail Yard Study (EPA Region 5 study)Source: Cicero Rail Yard Study Final Report, 2014 (EPA/600/R/12/621)

*UFPs = ultrafine particles (<100 nm)


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Example: Las Vegas Near-Road Study Source: Kimbrough et al., in preparation

0.00

0.20

0.40

0.60

0.80

1.00

-100 0 100 200 300

Norm

aliz

ed c

once

ntra

tion

Distance (m)

Winds from westBC

PM2.5

Freeway (relative to sites)

~40% difference in BC

~20% difference in PM2.5

0.0

0.2

0.4

0.6

0.8

1.0

0 500 1000 1500

Heavy-duty traffic volume

20 m roadside site

Downwind conditions

EPA Research: Grantees

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EPA’s extramural grant program: Website: https://www.epa.gov/research-grants/air-research-grants

New: Particulate Matter and Related Pollutants in a Changing WorldSeven of 13 future grants to investigate some aspect of wildfire impact on pollution and human health, e.g.:

• How climate and land use might change wildfire activity in the future• Assessment of future land use policies• How to appropriately model black and brown carbon from fires at

different scales

Clean Air Research Centers

2012: Measurements and Modeling for Quantifying Air Quality and Climate Impacts of Residential Biomass or Coal Combustion for Cooking, Heating and Lighting

2010: Black carbon’s role in global to local-scale climate and air quality

Summary

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• U.S. BC emissions have been declining, and additional reductions are expected by 2030 due to controls on mobile diesel engines.

• Ongoing partnership by EPA in international collaborations focused on black carbon emissions.

• Controlling direct PM2.5 emissions from sources can be a highly effective air quality management strategy, with major public health benefits.

• Black carbon continues to be an important research focus for EPA’s Office of Research and Development• Measurement methodology• Characterization of aerosol optical and chemical

properties of emission sources.• Useful as an indicator of source emissions impact on local

air quality

Thank you!

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• Many EPA colleagues noted on the slides – please feel free to directly reach out to them, or contact me and I am happy to help make connections for you.

Gayle HaglerEPA Office of Research and Development

[email protected]

overview of epa activities and research related to black

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