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Uncertainties in Heavy Metals Emission Inventories: Dimensions and Levels. S.Kakareka, T.Kukharchyk Institute for Nature Management National Academy of Sciences Minsk, Belarus. TFEIP/TFMM Workshop: 12 May 2010, Larnaca, Cyprus.
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Institute for Nature Management
National Academy of Sciences
TFEIP/TFMM Workshop: 12May 2010, Larnaca, Cyprus
Heavy metals emission uncertainty is a multidimensional and multi-aspect phenomena.
1. Sources of uncertainties in HM emission inventories: country dimension
a) Emission inventory methodology issues
Most of the EECCA countries widely use statistical emission data for reporting to EMEPwhich is bottom-up. EMEP emission inventory methodology is based on top-down approach. So questions of comparability of results obtained using different methodologies, possibilities of combining of two approaches and arising uncertainties are facing. These issues were tested on an example of Belarus.
Statistical, calculated by EMEP methodology and combined final emission values by sectors and totals were compared for heavy metals.
Calculated total lead emission is about 16 times higher than statistical. In final results share of statistical data is about 6 % only. Similar picture is typical for emissions of the most of other heavy metals: statistics account only small share of total heavy metal emissions. For mercury there is no statistical data on emission at all.
Statistical versus calculated emission data for lead in EMEP emission inventory
Shares of statistical and calculated data
So depending on applied methodology emission inventory results will be different.
Lead and mercury emission in Belarus in 2005, tons/50x50 grid cell
Differencies in spatial structures of emission depending on distribution algorithm:
Spatial structure of lead emission in East Europe by Webdab and expert estimates
A lot of studies were made last years on assessment of mercury emission from chlor-alkali production. But estimates are still uncertain; this reduce possibilities for detection of temporal and spatial trends of emission.
Chlor-alkali production is among key sources of mercury emission at global and regional scales. Its input estimated as 47-163 tons or 3-7% of global anthropogenic emission (Pirrone et al., 2009, 2010; AMAP/UNEP, 2008). For EECCA the input of chlor-alkali industry earlier was estimated as 26% of total mercury emission.
Our latest studies allowed to make following conclusions regarding mercury emissions from caustic soda and chlorine production since 1990 for EECCA region:
- descending trend of mercury emission is evident;
- absolute values of uncertainty are reducing;
- relative uncertainty remains high and not changed significantly;
- bias of emission level estimates is possible.
Trends of mercury emission in EECCA from caustic soda/chlorine production (low, high and ‘best’ estimates)
a) Reduction of caustic soda production by mercury cell method
A few caustic soda production enterprises have been closed or changed technology. On the whole distribution of production by technology type is known, but information for a certain enterprise is not easy to get so this can lead to uncertainties on a regional level and at spatial distribution of emission.
Data available shows that mercury consumption at EECCA caustic soda enterprises are decreasing: from 0.5 - 2 kg/ton caustic for the period before 1990, to 0.1 - 0.6 kg/t – in 1990th and to 0.04 - 0.6 kg/ton – in the beginning of 2000th. Mercury losses are still very different from plant to plant.
c) Reduction of mercury air emission (air emission factors).During production mercury is lost to the air, waste waters, products, solid wastes. Material balance methodology is prevailing for emission estimates especially in EECCA region. Share of mercury losses to the air is still uncertain. In many cases also share of unaccounted losses of mercury is very high - up to 50-80% of total losses, i.e. it is not known what media most of mercury is emitted.
Generally there is a significant lack of mercury air emission measurements. There are no published data on content of mercury in hydrogen, waste gases and ventilation air of electrolysis shops of this region. So air emission factors can be treated as greatest source of Hg emission estimates uncertainty for EECCA now; level of their uncertainty can hardly been reduced without air emission measurements campaigns.
There are a huge amount of mercury content wastes on the territory of EECCA – more than 1 mln tons, and annually more then 10 thous. tons mercury-containing wastes are formed additionally. Mercury content in these wastes varies from 10 to 750000 mg/kg. The most amount of waste are accumulated on the territory of non-ferrous metal, as well as chemicals, pulp-and paper, gold mining, electrothechnical enterprises. Account of emission from this source is lack.
Cement is a key source of mercury and is among large sources of other HM emission in Belarus.
Data from literature
Heavy metals emissions factors for cement production in Belarus for model facilities, g/t cement
Greatest contributor of HM into emission from cement production in Belarus is pyrite drosses. Their application is known on a facility basis; this allows to produce rather accurate spatially distributed HM emission estimates from this sector.
numerous factors affects accuracy/uncertainty of HM emission estimates;
they are different depending on the aspect of emission inventory concerned: emission totals, spatial resolution (distribution), time resolution etc.
Methods of uncertainties reduction are also numerous. Among perspective ones - balance method, which demands collection on a regular basis data on HM contents in raw materials, wastes, products. This method can be applied at a country, sector or facility level. So tracking of waste flows from non-ferrous industry and sulfuric acid production will allow to improve estimates of HM emission from cement production.