Urban air pollution and Acid rain

Pollutants Primary – emitted directly exhaust fumes factory chimneys Oil spills Secondary – primary reacts with substances in the atmosphere Tropospheric ozone VOC PAN’s

Gases from burning fossil fuels Carbon monoxide : It has no colour or smell. Nitrogen oxides: These gases also form acid rain. Hydrocarbons: produced when petrol is not fully burnt. They are one of the causes of modern-day smog.

Particulates: very small particles - like soot, dust and fumes that are released in the air. They are caused by vehicles, factories and smoke from homes burning coal for heating. Sulphur dioxide: released from power stations. Causes acid rain

Photochemical smog Mixture of many primary and secondary pollutants. Ozone, NOx, hydrocarbons and VOC’s interact with strong sunlight

NOx Gases Burn fossil fuels (exhaust fumes and power house emissions) – NO NO reacts with O – NO 2 – brown gas that contributes to urban haze Absorbs sunlight – release O to form Ozone

SOx Burn coal and oil – SO 2 Mixes with oxygen – Sulphates Mixes with water – sulphric acid

Troposheric Ozone Toxic gas and oxidizing agent Damages crops and forests Irritates eyes Breathing problems Increase susceptibility to infection Attack fabrics and rubber materials

Frequency and severity of photochemical smog Topography Climate Population density Fossil fuel use

Mexico City

Los Angeles

Rio de Janeiro

Beijing

Athens

Effects Ozone degrades chlorophyll Destroys natural rubber and plastic Bleaches fabric Humans suffer decreased lung function eye, nose and throat irritation

Pollution management Reduce: Use less electricity Increase passenger numbers in private cars Switch to renewable energy sources Clean up: Catalytic converters

Acid rain Dry deposition: Sulphates Nitrates Wet deposition Sulphuric acid Nitric acid Normal rain is pH5.6

What is pH? Measure of H ions. Not linear – pH2 is 10x more acidic than pH3

3 Types of Effects Direct effect Toxic effect Nutrient effect

Effects contamination of water supplies - harmful to human health (direct) cause chemical weathering of buildings (direct) crop yields reduced by increasing soil acidity (Nutrient) increased acidity of freshwater lakes killing both fish and plant life (toxic) important nutrients leached from the soil and replaced by aluminium which cause damage to plant and tree roots (toxic and nutrient)

Effects on buildings

Effects on Living organisms

Effects on soil

Replace Burning non-fossil fuels (i.e. nuclear or renewable fuels) Burning low-sulphur coal (can reduce sulphur emissions by up to 15%) Producing energy-efficient car engines Use lead-free petrol (major factor in reducing exhaust emissions in UK)

Regulate Fitting power stations with filters and low temperature burners (this is however expensive and to this nation wide, the costs may run into billions) 'Scrubbers' - equipment used to remove up to to 90% of sulphur dioxide emissions in coal- burning plants (but very expensive)

Case study 1950 – 1990 = 400 lifeless lakes in Scandinavia 1980 – Sweden use limestone – problem? International co-operation is essential to solve the problems caused by acid rain. 1980s - joint study between UK electricity generators /coal producers and Norway and Sweden to research the processes resulting in acid rain.

1979 Convention on Long range Transboundary Air Pollution Brought polluter and polluted together Set targets for reduction Polluters made to recognise responsibility

UK 1956 – Clean Air Act Smokeless zones Smoke control orders

International 1978 – Montreal Protocol Phase out CFCs and other chemicals Stratospheric ozone depletion 1997 – Kyoto Protocol Targets for reducing green house gases Why not successful?