Acid Rain

Acid Rain pH value – the measure of the acidity and alkalinity of a solution, range from 0 to 14 pH 7 is neutral pH>7 = alkaline pH<7 = acidic Natural rain in Hong Kong is about pH 6. Natural rain in Central Europe is pH 4.3, N. Europe, N. America and Japan is 3.5

Situation Acid rain(Acid deposition) Acid rain: pH > 5.5 Wet deposition: acidic rain, fog, hail and snow Dry deposition: acidic gases and particles Acid rain: pH > 5.5 Normal rain ~ pH 5.5 (CO2 dissolves in rain water  weak Carbonic acid) Acid rain can be as acidic as vinegar and lemon juice One of the Global Problems Widely spread (Prevailing winds disperse the pollutants far away from the sources) problem between national borders or frontier

What is the acid rain ? Acid Rain is caused when sulphur dioxide (SO2) and nitrogen oxides (NOx) chemically react with other substances in the atmosphere to form acidic compounds.Sunlight increases the reaction rate. They fall to the earth in wet and dry form.

Causes of acid rain [2] Main acid rain causing chemical Acid Rain Nitric Oxides (nitric oxide NO & nitric dioxide NO2) Sulfur dioxide SO2 Sulfuric acid H2SO4 Nitric acid HNO3 Acid Rain

Where do air pollutants come from ? Oil refineries, the use of coal in the production of electricity, from base-metal smelting, and from fuel combustion in vehicles.

Causes of acid rain [3] - sources Industry -- emission of acidic gases (e.g. smelting plant & power plant) Natural source of sulfur dioxide -- Volcanic Eruption Transportation -- source of acidic gases, mostly nitric oxides

Causes of acid rain [4] Chemical Process in Atmosphere dissolution 2H+ + SO42- H+ + NO3- O3 energy O2 NOx SO2 H2SO4 HNO3 oxidation

Effects of Acid Rain the acidification of lakes and streams forest damage decay of buildings and paint an increase in public health problems

LAKES AND STREAMS an acidity of between 6 and 8. Acid rain can cause a pH of as low as 3 in some places. cause to kill certain aquatic plant and animal life. Increase concentration of mercury, aluminium, manganese, lead and zinc in water. Norway and Sweden suffered most because no chalk and limestone (Geology)

Effects of acid rain [2] - water bodies When the water bodies is acidified, most of the aqueous species cannot survive and so the biodiversity decreases Lake - can be acidified easily as low water flow

This chart shows the different levels of acidity that certain lifeforms can handle.

FORESTS Acid rain causes direct damage to trees at high elevations, especially the red spruce. As shown in this picture from the EPA, large areas of forests have died. This occurs mainly in the very severe cases of acid rain, those causing a pH of 4 or less. Acidic soil causes the leaching of the nutrients from soil

Effects of acid rain [3] - forests Plant injury Soil acidified Further affect plant reproduction and growth Massive injury of plants by acid rain

MATERIALS damage certain materials ( limestone and marble) dissolves calcium carbonate in the stone forming crystals with stone and break apart stone

Effects of acid rain [4] - materials Status worn out by acid rain Marbles eroded by acid rain

PUBLIC HEALTH ~ also the contamination of edible fish. And crops ~ affect through both the water and the atmosphere. the pH of soil decreases, ~ the mobility of metallic compounds ( aluminum and mercury) increase ~ make them easily transported into the water system ~ lead to the contamination of not only the water ~ also the contamination of edible fish. And crops

Effects of acid rain [5] - human health Effects are usually indirect lung cancers, bronchitis, emphysema and asthma caused by inhalation

Acid Rain in the United States and Canada Acid rain is a large problem in the Eastern U.S. and Canada.This is mainly because emissions rise high into the atmosphere and are carried by the strong winds from the West, falling out with precipitation in the East.

Prevention: Reduce acidic gases emission [1] Good practice in fossil fuels combustion low sulphur coal used in power plants scrubbers used to remove sulphur dioxide from exhaust gas catalytic converters in vehicles reduce nitrogen oxides emission

Prevention: Reduce acidic gases emission [2] Application of clean energy resources nuclear power, hydropower, wind and geothermal energy high combust-efficient biomass fuel used in vehicles Wind-powered electricity plant

Mitigation: Restore damaged environment Liming neutralize acidity in lakes and streams however, not effective in damaged soil and watershed expensive

Improvements ~set up some regulations / law ~use Calcium carbonate / lime to neutralize the lakes and streams

Local actions 1984 Sweden $25 million to neutralize lakes 1985 USA 3-7 billions to control Encourage the industries to install some environmental facilities such as scrubber, electrostatic precipitator or using low sulphur content diesel, washing coal before use by tax break or by subsidization.

Individual actions Energy consumption is the main cause energy conservation help to avoid the problem

Is acid rain a serious problem in Hong Kong? Serious in some districts because of factories and acidic rain may have been emitted from the factories or brought from China causing pipelines rusting, paint peeling, kills trees and causing people suffer from respiratory diseases (bronchitis and asthma). However, Hong Kong has few historical building and sculptures. No large lakes or rivers with big fish populations. Little farming, no large forest.

To what extent do you think that acid rain in Hong Kong is caused by nearby territories, for example, mainland China? If acid rain in Hong Kong is caused partly by China, who should bear the responsibility and costs of combating it, and how would you justify your view? What would be the likely difficulties encountered in negotiation with China?

Discussion What are the natural sources of acid rains? How acid rains affect economic and agricultural activities? Can you show some evidences about buildings being destroyed by acid rain? Use of the nuclear power is a way to reduce the problem of acid rain, but is nuclear power an environmentally friendly fuel? What are some actions that individual can take to conserve energy & to reduce the problem of acid rain? Referring to section 1.1 Air Pollution, what is the trend of concentration of sulphur dioxide and nitrogen dioxide in Hong Kong? What is the implication of the trend on the problem of acid rain in Hong Kong?

International Efforts Convention on Long-range Transboundary Air Pollution, adopted on 13.11.1979, entered into force on 16.3.1983. Protocol to the 1979 Convention on Long-range Transboundary Air Pollution on Long-term Financing of the Cooperative Programme Monitoring and Evaluation of the Long-range Transmission of Air Pollutions in Europe (EMEP), adopted on 28.9.1984. Protocol to the 1979 Convention on Long-range Transboundary Air Pollution on the Reduction of Sulphur Emisssion or their Transboundary Fluxes by at least 30%, adopted on 8.7.1985.

Relevant websites Acid Rain 2000 (http://www.brixworth.demon.co.uk/acidrain2000/) U.S. Environmental Protection Agency - Acid Rain Program (http://www.epa.gov/airmarkets/acidrain/index.html) The site of Environment Canada - Atlantic Region (http://www.ns.ec.gc.ca/aeb/ssd/acid/acidfaq.html) EcoNet's Acid Rain Resources (http://www.econet.apc.org/acidrain/)

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