CONTRIBUTION FROM DIFFERENT VOC EMISSION SOURCES TO PHOTOCHEMICAL OZONE FORMATION IN EUROPE

Dick Derwent

rdscientific

This work was supported by the UK Department for Environment Food and Rural Affairs under contract number EPG 1/3/200

AIM OF THE PRESENTATION

To describe the contribution made by the different VOC emission sources to photochemical ozone formation over Europe.

UK PHOTOCHEMICAL TRAJECTORY MODEL

• Model description

A single air parcel following a trajectory across Europe

• Emissions of SO2, NOx, VOCs, CH4, CO and isoprene

From EMEP and UK NAEI inventories

• Master Chemical Mechanism

UK PHOTOCHEMICAL TRAJECTORY MODEL

MASTER CHEMICAL MECHANISM

• 137 emitted organic compounds• 4,414 reaction products• 12,871 chemical reactions

Detailed explicit chemical mechanism to represent the contribution made by each individual VOC species.

Developed by Michael Jenkin of Imperial College and Michael Pilling of University of Leeds and available at:

http://mcm.leeds.ac.uk/MCM

MASTER CHEMICAL MECHANISM

Generates the same picture of regional ozone formation across Europe as other mechanisms

Used here because it is the only mechanism that treats each emitted VOC species in explicit detail

VOC source categories can only be treated explicitly with a chemical mechanism that treats each species in detail

COMPARISON OF MCMv3.1 WITH CBM4 MECHANISM

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Travel time , hours

ozo

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MCMv3.1

CBM4

GRIDDED EMISSION INVENTORIES

VOC SPECIATION

UK NAEI

• 248 emission source categories at the SNAP 3 level• each has its own profile containing 667 VOC species• 248 x 667 matrix

UK Photochemical Trajectory Model

• 248 x 177 matrix of category x species• 90% coverage of total VOC mass emissions• fractional speciation held constant across Europe

EXPERIMENTAL DESIGN

• Base Case Experiment

Run with year 2000 VOC, NOx, SO2, CO, isoprene and CH4 emissions and year 2000 VOC fractional speciation

Ozone at arrival point 87.8 ppb

• 248 sensitivity cases

Run with the emissions from each VOC emission source category increased fractionally

Determine by difference the extra ozone formed

SENSITIVITY EXPERIMENTS

An additional emission was added in turn from each VOC emission source category across Europe.

The extra emission amounted to a 7.3% increase in VOC emissions.

The speciation of the extra emission was given the same species profile as the emission source category.

The increase in emission was applied everywhere across Europe

INCREMENTAL REACTIVITYOF A VOC EMISSION SOURCE CATEGORY

This is the increase in ozone in ppb divided by the fractional increase in the emissions from that source category:

O3

----------------------------

VOC

---------

VOC

Incremental reactivities depend on the environmental conditions and are not geophysical quantities

INCREMENTAL REACTIVITIES

Chemical waste incineration 53.8

Blast furnaces_Coke-oven gas 49.5

Iron & steel (Flaring)_Coke-oven gas 49.0

Iron & steel industry_Coke-oven gas 48.9

Other industrial combustion_Coke-oven gas 48.9

Industrial coatings (drum) 47.5

Printing (metal decorating) 47.1

Printing (heatset web offset) 47.0

Industrial coatings (marine) 46.5

Railways (Freight)_Gas oil 46.2

Road transport (rigid HGVs)_DERV 46.2

Other industrial (off-road)_Gas oil 46.0

CONTRIBUTION TO OZONE FORMATION

Ozone formation

= Incremental Reactivity x Fractional contribution

to total VOC emissions

CONTRIBUTION TO OZONE FORMATION

% incremental ozone

emissions reactivity ppb

Road transport (cars without catalysts)_Petrol 11.524 41.387 4.769

Road transport (cars with catalysts)_Petrol 5.264 41.578 2.189

Onshore loading of crude oil 5.098 31.532 1.608

Chemical industry 5.364 28.337 1.520

Offshore loading of crude oil 3.739 31.026 1.160

Spirit manufacture (maturation) 3.401 30.890 1.051

Refineries (process fugitives) 2.091 41.291 0.863

Petrol stations (vehicle refuelling with unleaded petrol) 2.709 31.327 0.849

Other solvent use 3.370 20.229 0.682

Gas leakage 4.648 13.527 0.629

Decorative paint (trade decorative) 1.811 31.395 0.569

Industrial coatings (metal & plastic) 1.627 34.835 0.567

Aerosols (cosmetics and toiletries) 1.883 28.638 0.539

Decorative paint (retail decorative) 1.669 31.313 0.523

Industrial adhesives 1.822 28.569 0.520

CONTRIBUTION TO OZONE FORMATION

Each source category has a different incremental reactivity because of the contribution from the different VOCs that make up its species profile.

Each source category makes a different contribution to ozone formation because of its different incremental reactivity and its different contribution to total emissions.

DOES IT MAKE ANY DIFFERENCE IF THE INFORMATION ABOUT THE INCREMENTAL REACTIVITIES IS USED IN

CONTROL STRATEGIES ?

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Percentage emissions

Ozo

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MCM

EMEP/RAINS

Based on incremental reactivities for 248 source categories

Base case 87.8 ppb

4 ppb

DOES IT STILL MAKE A DIFFERENCE AT THE HIGHLY AGGREGATED SNAP 1 LEVEL ?

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Percentage emissions

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EMEP/RAINS

1.9 ppb

Based on incremental reactivities of 11 SNAP 1 source categories

Road transport

solvents

Extraction & distribution of fossil fuels

CONCLUSIONS

• Incremental reactivities have been constructed for 248 VOC emission source categories.

• There is a factor of over 30 range in these incremental reactivities which is not represented in the EMEP/RAINS models.

• These variations in reactivity are caused by the different VOC species profiles for each source category.

• VOC control strategies targetting the most reactive source categories could be more cost-effective than currently estimated using the EMEP/RAINS models.