Chris DoreNETCEN, AEA Technology

Uncertainty in the UK Heavy Metal Emissions Inventory

1. Different Emissions Estimates & Inventories

MSC-E and McDonald Estimates Reverse modelling of concentration measurements to

derive emissions … and therefore all sources (1O & 2O) included

National Inventories Bottom-up compilation to comply with LTRAP … and therefore only 1O anthropogenic sources included

Not comparing Like for Like Differences will include natural sources, and all 2O, such

as resuspension

Driver for Improvements No international targets So no big improvement drivers for HMs limited EF development

2. UK Pb Emission Estimates Combustion Sources

Dependent on the metal content of fuels- how certain? our unleaded petrol EF is taken directly from UKPIA … but is considerably smaller than other EFs (ESPREME).

Process Emissions Usually very uncertain… … but expected to be small for Pb

“Other” Sources Resuspension Non anthropogenic Missing anthropogenic

2. UK Pb Emission Estimates

UK Emissions of Pb

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

tonn

es o

f Pb

OtherCorrectionRoad TransportMSC-E

2. UK Pb Emission Estimates

Conclusions- Pb

Unleaded petrol very low Pb content, and therefore highly uncertain measurements Information also suggests a large range of values … combined with a huge activity, means very high uncertainty Needs further investigation

Resuspension/”Other” Timeseries trend suggests a resuspension component … or “other” source (natural, unevaluated anthropogenic etc.) Whilst quantification is highly uncertain, methods suggest that

resuspension alone would not be sufficient to make up the shortfall.

3. Other UK HM Estimates Nickel & Vanadium

Similar liquid fuel content issues to Pb Current estimates considered to be over-estimates But cannot be assessed in detail until further metal content data become

available for the different fuels

Arsenic, Copper, Mercury and Zinc Burning of treated wood, tyre & brake wear, cremation and fireworks Sound methodologies, but high in uncertainty and could be underestimates.

• General Comment Some specific industrial sources probably under represented (metal

recycling, galvanising, some non-ferrous fugitives, natural).

4. Conclusions

1. High uncertainties, and uncertain uncertainties!

2. Care required to ensure comparing like-for-like

3. Improvement to some sources will probably require further measurement work to improve EFs

4. Feedback from the modellers is very helpful Evaluation/assessment of emissions Focus for inventory or model improvement

5. Improved two-way dialogue and transparency should be encouraged/promoted.

THANK-YOU FOR YOUR ATTENTION