Chris Dore NETCEN, 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 (1 O & 2 O ) included National Inventories Bottom-up compilation to comply with LTRAP … and therefore only 1 O anthropogenic sources included Not comparing Like for Like Differences will include natural sources, and all 2 O, 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 tonnes of Pb Other Correction Road Transport MSC-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