Air Quality and Freshwaters Transboundary Air Pollution in Europe A lecture by Dr Rick Leah University of Liverpool

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3 What causes acidity in the atmosphere? sulphur dioxide, mainly from power stations, oxides of nitrogen from motor vehicles and the industrial burning of fossil fuels (gas, oil and coal). Another form of nitrogen pollution, ammonia, is emitted especially in rural areas, e.g. from manure spread on farmland and from farm animals.

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7 Three related Problems Acid deposition Nitrogen Eutrophication Ground-level Ozone

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Biol Total deposition Source: The critical load / NILU. Maps : SKMe: Norwegian Mapping Authority - Environmental unit

Biol Three Major Changes 1.Lowering of pH (increase in H + ion) 2.Loss of basic ions (eg Ca 2+ ) 3.Increase in Aluminium + others such as mobilisation of Hg

Biol Interaction with Forestry Organic humus - Tendency to acidification Export of basic ions with forest products Makes system more sensitive to acid

Biol Historical Position Arguments over cause and effect Complexity of problem – leaves room for manoeuvre for vested interests Scientific work did not start until major environmental effects were widespread Evidence from the environment itself : Palaeolimnology

Biol Diatoms

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Acid sensitive Acid tolerant

Biol Critical Loads To help quantify effects and relate them to the acid deposited, an "effects based" approach, known as critical loads, has been developed. The critical load is a measure of sensitivity of the environment to pollutants.

Biol The Critical Load "the quantity of pollution that a part of the environment can tolerate without harmful effects occurring". Deposition above that limit may damage plants and animals. Where acidity critical loads are large, more acid deposition can be tolerated, but areas with small acidity critical loads are very sensitive to acidification.

Biol Capacity (to neutralise inputs) ie amounts of Na K Ca Mg Al Intensity Sensitivity

Biol Areas where excess deposition over the sensitive acidity critical loads is unlikely (pink), where excess is likely (red) and where the excess is high (black) as given by the deposition of sulphur, nitrogen oxide and ammonia;

Biol (estimated)

Biol Total deposition Source: The critical load / NILU. Maps : SKMe: Norwegian Mapping Authority - Environmental unit

Biol Atlantic salmon (Salmo salar) Effects of acidity are felt at all trophic levels Fish, especially salmonids are particularly susceptible

Biol Map: Regional distribution of areas with fish stocks affected by acidification in Norway Source: DN, Directorate for Nature Management.

Biol The Dipper (Cinclus cinclus )

Biol Remediation by neutralisation Lime (CaCO 3 ) is abundant and relatively cheap Reduces acidity but does not return to pristine condition because of alkalinity Can cause problems of increased toxicity of dissolve aluminium

Biol ,000 tonnes of lime used Calculated from government expenditure on lime, (with a fixed price of NOK 1,000 per tonne through the whole period. Source: Directorate for Nature Management).

Biol Treating the Symptoms  In 1995 lime was used over 2,500 locations in Norway covering a precipitation area of about 6,400 square kilometres   In 1994 £8.5 million were used on liming. The amount increased to £79 million in 1995 and then to £100 million in 1996

Biol Treatment : High Costs If the entire area of Southern Norway where the critical load has been exceeded should receive sufficient lime, the costs would be approximately £290 million according to the Norwegian Institute for Water Research.

Biol Removal at source is better than Remediation

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Biol Legislation 1979 Convention on Long Range Transboundary Air Pollution (LRTAP) 43 Signatories around the Northern Hemisphere

Biol Legislation for Reductions in Acid Emissions (I) Early Protocols for sulphur dioxide and oxides of nitrogen set simple targets for all countries: · a 30% reduction of sulphur emissions by 1993 · decreasing emission levels of oxides of nitrogen to those of 1987 (by 1994)

Biol Excess depositions of SO2 in Europe (in tons per square kilometer). No colour=no data. Source: EMEP

Biol Emissions of SO2 in 1000 tons, and by source. Source: Statistics Norway ("Natural Resources and the Environment 1997") / SFT

Biol Emissions of NOx in 1000 tons, and by source Source: Statistics Norway ("Natural Resources and the Environment 1997") / SFT

Biol Legislation for Reductions in Acid Emissions (II) In 1994, the new 'effects based' Protocol for sulphur, based on critical loads, was agreed in Oslo. This defined a target for each European country based on its pollutant emissions, the costs of abatement and the contribution those emissions made to acid deposition on sensitive ecosystems across Europe.

Biol The Multi-pollutant, Multi-effect Protocol was signed in Gothenburg in It takes into account effects of acidity, excess nutrient nitrogen and also photochemical oxidants (low level ozone).

Biol Recovery

Biol Recovery Slow processes are involved Calculations show that to achieve recovery at the most sensitive sites, emissions of sulphur, oxides of nitrogen and ammonia must be decreased further still.

Biol For some sensitive areas, however, critical loads may be unattainable with current emission control technology, so recovery may not be possible through emission decreases alone in the foreseeable future Other methods may be used to aid their recovery. For example, in many lakes in Scandinavia, the addition of lime continues to be used as an interim measure for neutralising acidification.