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

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

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

1. Principles of Uncertainty

2. Combustion Sources Solid 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 Concentrations (ppm) of metals in bituminous coals (Smith 1987)

2. Combustion Sources Solid 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

2. Combustion Sources Petroleum 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

2. Combustion Sources Pb 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)

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

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)

3. Non-Combustion Sources Tyre & Break Wear Important for Zn and Cu Estimates are a fixed fraction of PM 10 emission from these sources Tyre wear is easy to estimate, but PM 10 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.)

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

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.

5. Mapping Emission Estimates

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 PM 10 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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