Chris Dore AEA Energy and Environment

1. Uncertainties in the UK Heavy Metal EmissionsInventory Chris Dore AEA Energy and Environment UK Emissions Inventory Programme Funded by Defra: RMP2106

2. Contents 1. Principles of Uncertainty 2. Combustion Sources 3. Non-Combustion Sources 4. “Missing” & Non-Anthropogenic Sources 5. Mapping Emission Estimates 6. Conclusions

3. 1. Principles of Uncertainty • Combination of uncertainties • Point sources- combination of random independent errors • Area sources- one EF, prone to bias.

4. 1. Principles of Uncertainty

5. 2. Combustion SourcesSolid Concentrations (ppm) of metals in bituminous coals (Smith 1987) Coal, Coke, Anthracite & SSF • Important for As, Cd, Cr, Pb, Be and a major source of Mn, Hg & Se • Point Sources • Well characterised, and emissions data are reported. Hence no bias is expected. • But possible issues associated with extrapolation of few measurements

6. 2. Combustion SourcesSolid Coal, Coke, Anthracite & SSF • In 2005, over 2/3 of UK steam coal was imported • ~80% from Russia/South Africa, 13% from Columbia/Indonesia. • Distribution with the ranges shown is not known. • Fugitive emissions from Coke Ovens • Area Sources • Median values taken from a wide range • Fuels assumed to be the same as coal • Limited information on PM control • Potential for significant bias

7. 2. Combustion SourcesPetroleum Petroleum Fuels • Important for all metals except Cr and Hg, major sources of Be, Cd, Ni, Se, V & Zn • Metal emissions are primarily associated with petroleum coke, waste lubricants & fuel oil (higher metal contents) • However, large volumes of gas oil, DERV and petrol are consumed, giving notable contribution, despite their lower metal contents. • Point Sources • Variability would result in little impact on emissions total • Area Sources • Metal content taken from literature values • Fuel oil: variability of 2-4 times the mean value • Gas oil/DERV: very variable metal content data • Waste lubricants (10% of Pb): factor of ~10 variability metal content

8. 2. Combustion SourcesPb in Petrol Pb in Petrol, and Unleaded Petrol • UK uses EF’s based on measurement data • Pb content of “unleaded” = 0.04 mg/l (UKPIA 2003) • 70% assumed to be released to air • Small when compared to the limit value (5 mg/l)

9. 2. Combustion Sources Burning of CCA Treated Wood • “CCA” Cu, Cr As treated wood. • Major source for As, important for Cr • Data available on As consumed in CCA preservatives. • But v difficult to estimate the quantities of wood burned • Cr and Cu emissions extrapolated from As data • Estimates could be out by a factor of 20. Cremation • Well characterised in the UK • Uncertainties of Hg would give a maximum impact of 10% increase to the UK total. Other Fuels • Scrap tyres, MSW and wood in power stations • Not a particularly large source

10. 3. Non-Combustion Sources • Metal Industry Processes • Important for most metals • Includes processes at steelworks (sintering and blast, basic oxygen, & electric oxygen furnaces), foundries, 1° Al production, 2° Pb & Al production, and various other non-ferrous metal processes • Variety of point source data and literature data. • Estimates are likely to only include stack emissions, and fugitives are therefore not accounted for. • Chloroalkali Processes • Important for Hg • The main source is associated with the ventilation air from the cell room • Very difficult to asses for a variety of reasons, assume that the emission could be underestimated by a factor of five (also used for other fugitive emissions)

11. 3. Non-Combustion Sources Tyre & Break Wear • Important for Zn and Cu • Estimates are a fixed fraction of PM10 emission from these sources • Tyre wear is easy to estimate, but PM10 emission less so. UK specific data. Metal concentrations in tyres are highly variable (less so for HGV’s). • Metal content of brake linings is fairly well characterised. • Emissions per vkm vary by nearly an order of magnitude. UK specific data. • “Odd and Ends” • A variety of other sources included in the inventory (fireworks, glass manufacture, waste incineration etc.)

12. 4. Missing & Non-anthropogenic Sources “Missing” Sources • Accidental/malicious fires • dwellings, factories, other buildings, vehicle fires • Demolition • Corrosion/abrasion of metal structures • Galvanizing • Non-thermal processing of scrap metals • e.g. shredding of scrap metals • Part B industrial processes • e.g. cement batching, quarrying, powder coating • Abrasion of road surfaces by motor vehicles

13. 4. Missing & Non-anthropogenic Sources Non-anthropogenic Sources • Natural Sources • not currently included or estimated. Estimates available from Ilyin & Travnikov (2005) • Marine Sources • not currently included or estimated. Estimates available from Ilyin & Travnikov (2005) • Resuspension • Estimates available from Ilyin & Travnikov (2005) suggest significant contributions for Pb and Cd (trebling the 2004 Cd emissions in the UK). • However estimates from Vincent and Passant (2006) for Cd, Pb, As, Ni suggested resuspension was not a major source.

14. 5. Mapping Emission Estimates

15. 6. Conclusions • Conclusions • There are areas where improvements need to be made • However we are currently limited by data availability • Recommendations for Future work • Point Sources: Obtain more information on whether fugitive emissions are included in current estimates • Combustion Sources: Obtain more comprehensive data on metal content of fuels • Brake and Tyre Wear: Review and consolidate existing literature information • “Missing” Sources: Make some initial estimates by improving PM10 estimates (not straightforward!) • Natural Sources: Incorporate estimates into emissions inventory • Validation & Verification • After conducting these improvements, reassess the estimates derived from modelling in light of updated emissions inventory estimates.

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