Name Lim Jhin Horng

IC Number 930502-04-5155

Class 6 Rendah Sains 1 (6RS1)

School Sekolah Menengah Kebangsaan Dang Anum

Topic Acid Rain

Teacher – in – charge Puan Adilah Adran

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INDEXSection Page Number

Introduction 3

Definition 3 – 4

History 4 – 6

Source of Pollutants that Leads to Acid Rain

7 – 21

Chemical Process 21 – 22

Acid Deposition 22

Adverse Effects 22 – 31

Affected Area 32

Prevention Method 32 – 33

Reference 34

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INTRODUCTIONAcid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions, H−¿ ¿, which makes it to have low pH. Acid rain can be harmful to plants, aquatic animals and infrastructure through the process of wet deposition. It is caused by the emissions of sulphur dioxide, SO2 and nitrogen oxide, NO2 which react with water molecules in the atmosphere to produce acids. Governments have made efforts since the 1970s to reduce the release of sulphur dioxide into the atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes while sulphur dioxide is produced by volcanic eruptions.

DEFINITIONAcid rain is a popular term referring to the deposition of wet (rain, snow, sleet, fog, cloud water and dew) and dray (acidifying particles and gases) acidic component. A more accurate term is supposed to be “acid deposition”. Distilled water, once carbon dioxide is removed, has a neutral pH of 7.0. Liquids with a pH less than 7 are acidic and those with a pH greater than 7 are alkaline (refer picture below). “Clean” or unpolluted rain has a slightly acidic pH, which is greater than 5.7 because it contain carbon dioxide, CO2 and water, H2O in the air react together to form carbonic acid, H 2 CO3. Besides carbon dioxide, unpolluted rain also contains other chemicals too.

H 2 O ( I )+CO2 ( g )⇌H 2 CO3(aq)

Carbonic acid can then ionize in water to form a low concentration of hydronium and carbonate ions

H 2 O ( I )+H 2CO3 (aq )⇌HCO3−¿ (aq) +H 3 O+¿¿ ¿

Acid deposition as an environmental issue would include additional acids to H 2 CO3.

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HISTORY

The corrosive effect of polluted, acidic city air on limestone and marble was noted in the 17th century by John Evelyn, who remarked upon the poor condition of the Arundel Marbles. Since the Industrial Revolution, emissions of Sulphur Dioxide and Nitrogen Oxides to the atmosphere have increased. In 1852, Robert Angus Smith was the first to show the relationship between acid rain and atmospheric pollution in Manchester, England. Though acidic rain was discovered in 1852, it was not until the the late 1960s that scientists began widely observing and studying the phenomenon. The term “acid rain” was coined in 1872 by Robert Angus Smith. Canadian Harold Harvey was among the first to research a “dead” lake. Public awareness of acid rain in the US increased in the 1970s after The New York Times promulgated reports from the Hubbard Brook Experimental Forest in New Hampshire of the myriad deleterious environmental effects demonstrated to result from it.

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Tress killed by acid rain

Occasional pH readings in rain and fog water of well below 204 have been reported in industrialized areas. Industrial acid rain is a substantial problem in China and Russia and areas down-wind from them. These areas at the same time burn coal (sulphur-containing) to generate heat and electricity. The problem of acid rain not only has increased with population and industrial growth, but has become more widespread. The use of tall smokestacks to reduce local pollution has contributed to the spread of acid rain by releasing gases into regional atmospheric circulation. Often deposition occurs a considerable distance downwind of the emissions with mountainous regions tending to receive the greatest deposition (simply because of their higher rainfall). An example of this effect is the low pH of rain (compared to the local emissions) which falls in Scandinavia.

History of acid rain in the United States

Since 1998, Harvard University wraps some of the bronze and marble statues on its campus, such as this “Chinese Stele” with waterproof covers every winter, in order to protect them from erosion caused by acid rain (or, actually, acid snow).

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In the 1980s, the US Congress passed an Acid Deposition Act. This Act established a 10-year research program under the direction of the National Acidic Precipitation Assessment Program (NAPAP). NAPAP looked at the entire problem. It enlarged a network of monitoring sites to determine how acidic the precipitation actually was, and to determine long term trends and established a network for dry deposition. It looked at the effects of acid rain and funded research on the effect of acid precipitation on freshwater and terrestrial ecosystems, historical buildings, monuments and building materials. It funded extensive studies on atmospheric processes and potential control programs.

In 1991, NAPAP provided its first assessment of acid rain in the United States. It reported that 5% of New England Lakes were acidic with sulphates being the most common problem. They noted that 2% of the lakes could support Brook minnow. Subsequent Reports to Congress have documented chemical changes in soil and freshwater ecosystems, nitrogen saturation, decreases in amounts of nutrients in soil, episodic acidification, regional haze and damage to historical monuments.

Meanwhile, in 1990, the US Congress passed a series of amendments to the Clean Air Act. Title IV of these amendments established the Acid Rain Program, a cap and trade system designed to control emission of sulphur dioxide and nitrogen oxides. Title IV called for a total reduction of about 10 million tons of SO2 emissions from power plants. It was implemented in 2 phases. Phase 1 began in 1995 and limited sulphur dioxide emissions from 110 of the largest power plants to a combined total of 807 million tons of sulphur dioxide. One power plant in New England (Merrimack) was in Phase I. 4 other plants (Newington, Mount Tom, Brayton Point and Salem Harbour) were added under other provisions of the program. Phase II began in 2000 and affects most of the power plants in the country.

During the 1990s, research continued. On March 10, 2005 issued the Clean Air Interstate Rule (CAIR). This rule provides states with a solution to the problem of power plant pollution that drifts from one state to another. CAIR will permanently cap emissions of SO2 and NOx in the eastern United States. When fully implemented, CAIR will reduce SO2 emissions in 28 eastern states and the District of Columbia by over 70 percent and NOx emissions by over 60 percent from 2003 levels.

Overall, the Program’s cap and trade program has been successful in achieving its goals. Since the 1990s, So2 emissions have dropped 40% and according to the Pacific Research Institute, acid rain levels have dropped 65% since 1976. However, this was significantly less successful than conventional regulation in the European Union, which saw a decrease of over 70% in SO2 emissions during the same time period.

In 2007, total SO2 emissions were 8.9 million tons, achieving the program’s long term goal ahead of the 2010 statutory deadline.

The EPA estimates that by 2010, the overall costs of complying with the program for businesses and consumers will be $1 billion to $2 billion a year, only one fourth of what was originally predicted.

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Source of Pollutants That Leads to Acid RainThe most important gas which leads to acidification is sulphur dioxide. Emission of nitrogen oxides which are oxidized to form nitric acid are of increasing importance due to the stricter controls on emissions of sulphur containing compounds. 70Tg (S) per year in the form of SO2 comes from fossil fuels combustion and industry, 2.8Tg (S) from wildfires and 7 – 8Tg (S) per year from volcanoes.

Carbon dioxide, CO2

Fossil Fuel Combustion

When fossil fuels are burned to produce energy the carbon stored in them is emitted almost entirely asCO2. The main fossil fuels burned by humans are petroleum (oil), natural gas and coal. CO2 is emitted by the burning of fossil fuels for electricity generation, industrial uses, transportation, as well as in homes and commercial buildings. In 2006, petroleum supplied the largest share of domestic energy demands, accounting for an average of 47 percent of total fossil-fuel-based energy consumption

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in 2006. Coal and natural gas followed in order of importance, accounting for 27 and 26 percent of total fossil fuel consumption, respectively. The figure below displays emissions for each of these sectors, by fuel type in 2006.

Electricity Generation

The process of generating electricity is the single largest source of CO2 emissions in the United States, representing 41 percent of all CO2 emissions. The electric power industry includes all power producers - both regulated utilities and other entities (e.g., independent power producers, co-generators, etc.). Total national emissions in the U.S. depend upon the amount of electricity generated and the mix of fuels used to produce the electricity. For example, increases and decreases in the share of electricity generated by burning coal can affect total national emissions. Emissions from electricity generation can be reduced by:

Increasing the share of electricity generated from low carbon fuel or renewable sources. EPA’s Clean Energy Programs are designed to help consumers improve their knowledge about their Clean Energy options by providing objective information, creating networks between the public and private sector and providing technical assistance.

Lowering total electricity consumption by consumers through improvements in energy efficiency.

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Industry

The industrial sector engages in activities such as manufacturing, construction and mining. Within manufacturing, six industries – petroleum refining, chemical production, primary metal production, paper, food, and mineral production – represent the majority of energy use. Industry consumes significant amounts of electricity, but in the national inventory, only direct onsite CO2 emissions are allocated to this sector. Since 1990, industrial output in the United States has grown significantly, but CO2

emissions experienced only a modest increase.

A number of industrial companies have joined EPA's Climate Leaders program and taken on voluntary commitments to reduce their emissions of greenhouse gases.

Residential and Commercial

The residential and commercial sectors are heavily reliant on electricity for meeting their energy needs, particularly for lighting, heating, air conditioning and appliances. The main source of direct CO2 emissions is the burning of natural gas and oil for heating and cooling of buildings.

Transportation

The transportation sector is the second largest source of CO2 emissions in the U.S. Almost all of the energy consumed in the transportation sector is petroleum based, including gasoline, diesel and jet fuel. Automobiles and light-duty trucks account for almost two-thirds of emissions from the transportation sector and emissions have steadily grown since 1990. Other sources of transportation emissions are freight trucks, aircraft, trains and boats.

Emissions from transportation depend on the number of trips or miles travelled by each type of vehicle each year, which are in turn influenced by larger economic trends and consumer behaviour. Over the long term, changes in the fuel efficiency of vehicles (e.g., mileage), and in the type of fuel used can also influence the level of emissions.

EPA has developed a number of programs designed to lower the impact of automobile emissions on the environment:

The Smart Way Transport Partnership is a collaborative voluntary program between EPA and the freight industry that will increase the energy efficiency and energy security of our country while significantly reducing air pollution and greenhouse gas emissions.

The Green Vehicle Guide helps consumers choose the cleanest and most efficient vehicles that meet their needs. The Guide rates cars and trucks according to their emissions and fuel economy performance and provides consumers with information on how to make environmentally-informed choices when purchasing vehicles.

The U.S. Department of Energy Hydrogen Program works in partnership with industry, academia, national laboratories, federal and international agencies to

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overcome technical barriers, address safety concerns and demonstrate fuel cell technologies in various applications, including the transportation sector.

Carbon Sequestration

Carbon sequestration is the process through which plant life removes CO2 from the atmosphere and stores it in biomass. Over the course of a year, plants remove and release CO2 and net sequestration results if the rate of removal is higher than the rate of release. Young, fast-growing trees in particular will remove more carbon dioxide from the atmosphere than they will release. Agricultural and forestry practices can enhance the rate of carbon sequestration, or cause net emissions, depending on the overall balance. The term “sink” is a broader term used to describe agricultural and forestry lands or other processes that absorb or sequesterCO2, and other chemical processes that remove other greenhouse gases from the atmosphere (e.g., methane).

All land areas such as farms, grasslands and forests can be sources or sinks of CO2, depending on the particular agricultural and forestry practices on these lands. In the U.S., forests and other types of lands have been significant sinks since 1990, due in large part to forest and soil management practices. Nationally, carbon sequestration offset or removed 13 percent of total greenhouse gas emissions in 2006. The largest share came from forest growth, increasing forest area and an increase in the amount of carbon stored in durable wood products. The rate of carbon sequestration has decreased since 1990, particularly in forests.

Deforestation

Permanent removal of standing forests leads to CO2 emissions because the carbon sequestered in trees is emitted to the atmosphere and not counter-balanced by re-growth of new trees. Typically, CO2 is either emitted quickly through burning or slowly through decomposition over time. Deforestation is a significant source of carbon dioxide emissions globally, but a minor source in the U.S.

Geologic Sequestration

Geologic sequestration refers to a chain of activities that result in collection and transport of concentrated CO2 gas from large emission sources, such as power plants, and subsequent injection into deep underground reservoirs. Currently, carbon storage takes place mainly at oil and gas production facilities, but storage in other types of reservoirs may increase in the future as technologies continue to develop.

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Sulphur Dioxide, SO2

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Carbon Monoxide, CO

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Figure 1: Source of Sulphur Dioxide 2005

Figure 2: Source of Sulphur Dioxide 2006

Unvented kerosene and gas space heaters; leaking chimneys and furnaces; back-drafting from furnaces, gas water heaters, wood stoves, and fireplaces; gas stoves; generators and other gasoline powered equipment; automobile exhaust from attached garages; and tobacco smoke. Incomplete oxidation during combustion in gas ranges and unvented gas or kerosene heaters may cause high concentrations of CO in indoor air. Worn or poorly adjusted and maintained combustion devices (e.g., boilers, furnaces) can be significant sources, or if the flue is improperly sized, blocked, disconnected, or is leaking. Auto, truck, or bus exhaust from attached garages, nearby roads, or parking areas can also be a source.

Propane-powered Forklift

Gasoline Concrete Cutter

Gasoline Pressure Washer

Propane Space Heater

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Propane-powered Floor Polisher

Figure 3: Carbon Monoxide On Road Mobile Sources

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Figure 4: Carbon Monoxide Non road Mobile Sources 1

Chlorofluorocarbons (CFCs)

The primary source of release to the environment is from air emissions from their use in aerosols and leakage from refrigeration equipment with a smaller proportion from surface water discharges. There are no natural sources of release to the environment.

Lead, Pb

Paint

Lead was used in paint to add colour, improve the ability of the paint to hide the surface it covers, and to make it last longer. In 1978 the federal government banned lead paint for use in homes. Homes built before 1978 probably contain lead-based paint. Painted toys and furniture made before 1978 may also contain lead-based paint.

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Lead-based paint becomes a concern when it chips, turns into dust, or gets into the soil.

Dust

Lead dust is the most common way that people are exposed to lead. Inside the home, most lead dust comes from chipping and flaking paint or when paint is scraped, sanded, or disturbed during home remodelling. Chipping and peeling paint is found mostly on surfaces that rub or bump up against another surface. These surfaces include doors and windows. Young children usually get exposed to lead when they put something with lead dust on it into their mouths. Lead dust may not be visible to the naked eye.

Soil

Starting in 1973, the federal government started a gradual phase-down of lead content in gasoline, and by 1996, banned the sale completely. However, lead from car exhausts mixed with soil near roads and is still there today. Homes near busy streets may have higher levels of lead in the soil. Today, lead still comes from metal smelting, battery manufacturing, and other factories that use lead. This lead gets into the air and then mixes with the soil near homes, especially if the home is near one of these sources. Flaking lead-based paint on the outside of buildings can also mix with the soil close to buildings. Lead-based paint mixing with soil is a problem during home remodelling if workers are not careful. Once the soil has lead in it, wind can stir up lead dust, and blow it into homes and yards.

Drinking Water

Lead seldom occurs naturally in water supplies like rivers and lakes. Lead enters drinking water primarily as a result of the corrosion, or wearing away, of materials containing lead in the water distribution system and household or building plumbing. These materials include lead-based solder used to join copper pipe, brass and chrome plated brass faucets, and in some cases, pipes made of lead that connect houses and buildings to water mains. In 1986, Congress banned the use of lead solder containing greater than 0.2% lead, and restricted the lead content of faucets, pipes and other plumbing materials to 8.0%. Older construction may still have plumbing that has the potential to contribute lead to drinking water.

Air

Lead can be present in outdoor and indoor air. Lead in outdoor air comes mainly from industrial sources (e.g., smelters, waste incinerators, utilities, and lead-acid battery manufacturers). Wind-blown soil and road dust also may contain naturally occurring lead as well as lead from industrial sources, deteriorated paint, and the combustion of leaded gasoline and aviation fuel. Sources of lead in indoor air include outdoor air, suspended dust, and some hobbies (e.g., making stained glass objects using lead solder, shooting using lead bullets at indoor firing ranges).

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Folk medicines, ayurvedics and cosmetics

Some folk medicines contain lead. They often are imported from the Middle East, Southeast Asia, India, the Dominican Republic, or Mexico. Two examples are Greta and Azarcon. Azarcon is a bright orange powder also known as Maria Luisa, Rueda, Alarcon, and Coral. Greta is a yellow powder. They are used to treat an upset stomach. Pay-loo-ah also contains lead. It is a red powder used to treat a rash or a fever. Other folk medicines that contain lead include Bala (or Bala Goli), Golf, Ghasard, and Kandu. Some cosmetics such as Kohl (Alkohl) and Surma also contain lead.

Ayurveda is a traditional form of medicine practiced in India and other eastern Asian countries. Ayurvedic medications may contain herbs, minerals, metals, or animal products. These medicines may come in both standardized and non-standardized formulations. Ayurvedic medications are typically imported into the United States by both practitioners and followers of Ayurvedic medicine.

Children's jewellery and toys

Lead has been found in inexpensive children's jewellery sold in vending machines and large volume discount stores across the country. It also has been found in inexpensive metal amulets worn for good luck or protection. Some costume jewellery designed for adults has also been found to contain lead. It is important to make sure that children don't handle or mouth any jewellery.

The workplace and hobbies

People exposed to lead at work may bring lead home on their clothes, shoes, hair, or skin. Some jobs that expose people to lead include: home improvement; painting and refinishing; car or radiator repair; plumbing; construction; welding and cutting; electronics; municipal waste incineration; lead compound manufacturing; manufacturing of rubber products, batteries, and plastics; lead smelting and refining; working in brass or bronze foundries; demolition; and working with scrap metal.

Some hobbies also use lead. These hobbies include making pottery, stained glass, or refinishing furniture. Hunters who make their own bullets or anglers who make their own fishing sinkers can be exposed to lead fumes if they don't follow good practices (see www.nyhealth.gov/environmental/outdoors/fish/fish.htm). Fishing tackle (especially sinkers and jig heads) often contains lead. It is important to keep all lead objects away from children. Wash hands with soap and water after holding or using lead sinkers and jig heads or reloading lead bullets or shot. Never bite down on lead sinkers.

Lead-glazed ceramics, china, leaded crystal, pewter

Lead may get into foods or liquids that have been stored in ceramics, pottery, china, or crystal with lead in it. Lead-glazed dishes usually come from other countries.

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Imported candies or foods, especially from Mexico, containing chilli or tamarind

Lead can be found in candy, wrappers, pottery containers, and in certain ethnic foods, such as chap lines (dried grasshoppers).

Imported food in cans that are sealed with lead solder

In 1995 the United States banned the use of lead solder on cans. But lead solder can still be found on cans made in other countries. These cans usually have wide seams, and the silver-gray solder along the seams contains the lead. Cans containing lead may be brought to the United States and sold. Over time the lead gets into the food. This happens faster after the can has been opened. Foods that are acidic cause lead to get into the food faster.

Firearms with lead bullets

People can also be exposed to lead by eating venison and small game harvested with lead shot and lead bullets. Recent research indicates that small lead fragments are often present in venison from deer harvested with lead bullets. Some bullets shatter into small pieces that can be too small to detect by sight, feel, or when chewing the meat. People can also be exposed to lead when it is released into the air when a gun is fired particularly in indoor shooting ranges. Lead particles are also formed as the lead bullet spirals through the barrel. These particles of lead can get into your body when you breathe or swallow, and lead dust can get on your food, cigarettes, or other items that you eat, drink, or put in your mouth.

Mini-blinds

Some non-glossy, vinyl mini-blinds from foreign countries contain lead.

Consumer Products

Batteries, radiators for cars and trucks, and some colours of ink also contain lead.

Nitrogen Oxides, NOx

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Direct Sources

A major direct source of nitrous oxide from agricultural soils is that of synthetic fertilizer use. Widespread increase in the use of such nitrogen based fertilizers has been driven by the need for greater crop yields, and by more intensive farming practices.

Where large applications of fertilizer are combined with soil conditions favourable to denitrification, large amounts of nitrous oxide can be produced and emitted to the atmosphere.

Similarly, the widespread and often poorly controlled use of animal waste as fertilizer can lead to substantial emissions of nitrous oxide from agricultural soils. Some additional nitrous oxide is thought to arise in agricultural soils through the process of nitrogen fixation, though the true importance of this source remains poorly defined.

Human Impact

Man's need for more food, as a result of an expanding global population, has inevitably led to an increase in the use of both synthetic fertilizer and the wider application of animal waste on agricultural soils. However, the application of such nitrogen based fertilizers in many areas has been excessive, with large proportions of the added fertilizer providing no benefit to crop yield, but inducing elevated nitrous oxide emissions.

Potential for control

The better targeting of fertilizer applications, both in space and time, can significantly reduce nitrous oxide emissions from agricultural soils. Land-management strategies which accurately take account of the optimum amounts of fertilizer addition necessary for maximum crop yield and minimum waste are crucial both environmentally and economically. Similarly, the exact form of nitrogen based fertilizer and the best time of year at which to use them is key information on which to base fertilization campaigns

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Indirect Sources

Indirect agricultural sources of nitrous oxide remain poorly defined in most cases. There are several ways in which such indirect emissions occur. The most important of these is nitrous oxide emission arising from nitrogen leaching and run-off from agricultural soils.

After fertilizer application or heavy rain, large amounts of nitrogen may leach from the soil into drainage ditches, streams, rivers and eventually estuaries. Some of the nitrous oxide produced in agricultural soils is lost in exactly this way, being emitted to the atmosphere as soon as the drainage water is exposed to the air.

Still more nitrous oxide is produced from such drainage waters when the leached nitrogen fertilizer they contain undergoes the processes of nitrification or denitrification in aquatic and estuarine sediments. Other important indirect nitrous oxide sources from agricultural soils include the volatilization and subsequent deposition of ammonia from fertilizer application, and the consumption of crops followed by sewage treatment.

Human Impact

As with direct nitrous oxide emission from agricultural soils, man takes full responsibility for indirect emission. Not only do large quantities of leached nitrogen based fertilizer have a significant impact on indirect nitrous oxide emissions, they have also led to dangerously high nitrate concentrations in drinking water and to eutrophication in rivers and estuaries around the world. Increased food consumption and consequent increases in municipal sewage treatment have also inevitably led to increased indirect nitrous oxide emissions from this source.

Potential for control

Again, it is through properly informed land-management practice and fertilization campaigns that nitrous oxide emissions can primarily be reduced. Much of the impetus for control of nitrogen based fertilizers has come from concern over high nitrate levels in drinking water supplies and the threat of

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eutrophication in estuaries and coastal waters. Individual governments have enacted changes in policy to bring about reductions in such nitrogen leaching, with the creation of 'Nitrate Sensitive Zones' (NSZs) requiring particular attention in the UK.

Chemical processes

Combustion of fuels creates sulphur dioxide and nitric oxides. They are converted into sulphuric acid and nitric acid.

Gas phase chemistry

In the gas phase sulphur dioxide is oxidized by reaction with the hydroxyl radical via an intermolecular reaction.

SO2 + OH· → HOSO2·

Then, it is followed by:

HOSO2· + O2 → HO2· + SO3

In the presence of water, sulphur trioxide (SO3) is converted rapidly to sulphuric acid:

SO3 (g) + H2O (l) → H2SO4 (l)

Nitrogen dioxide reacts with OH to form nitric acid:

NO2 + OH· → HNO3

Chemistry in cloud droplets

When clouds are present, the loss rate of SO2 is faster than can be explained by gas phase chemistry alone. This is due to reactions in the liquid water droplets.

Hydrolysis

Sulphur dioxide dissolves in water and then, like carbon dioxide, hydrolyses in a series of equilibrium reactions:

SO2 (g) + H2O SO2·H2O

SO2·H2O H+ + HSO3−

HSO3− H+ + SO3

2−

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Oxidation

There are a large number of aqueous reactions that oxidize sulphur from S(IV) to S(VI), leading to the formation of sulphuric acid. The most important oxidation reactions are with ozone, hydrogen peroxide and oxygen (reactions with oxygen are catalyzed by iron and manganese in the cloud droplets).

Acid deposition

Wet deposition

Wet deposition of acids occurs when any form of precipitation (rain, snow, and so on.) removes acids from the atmosphere and delivers it to the Earth's surface. This can result from the deposition of acids produced in the raindrops (see aqueous phase chemistry above) or by the precipitation removing the acids either in clouds or below clouds. Wet removal of both gases and aerosols are both of importance for wet deposition.

Dry deposition

Acid deposition also occurs via dry deposition in the absence of precipitation. This can be responsible for as much as 20 to 60% of total acid deposition. This occurs when particles and gases stick to the ground, plants or other surfaces.

Adverse EffectsEffect on Lakes and Streams

Many lakes and streams examined in a National Surface Water Survey (NSWS) suffer from chronic acidity, a condition in which water has a constant low pH level. The survey investigated the effects of acidic deposition in over 1,000 lakes larger than 10 acres and in thousands of miles of streams believed to be sensitive to acidification. Of the lakes and streams surveyed, acid rain caused acidity in 75 percent of the acidic lakes and about 50 percent of the acidic streams. Several regions in the U.S. were identified as containing many of the surface waters sensitive to acidification. They include the Adirondacks and Catskill Mountains in New York State, the mid-Appalachian highlands along the east coast, the upper Midwest, and mountainous areas of the Western United States. In areas like the North-eastern United States,

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where soil-buffering capacity is poor, some lakes now have a pH value of less than 5. One of the most acidic lakes reported is Little Echo Pond in Franklin, New York. Little Echo Pond has a pH of 4.2.

Acidification is also a problem in lakes that were not surveyed in federal research projects. For example, although lakes smaller than 10 acres were not included in the NSWS, there are from one to four times as many of these small lakes as there are larger lakes. In the Adirondacks, the percentage of acidic lakes is significantly higher when it includes smaller lakes.

Streams flowing over soil with low buffering capacity are as susceptible to damage from acid rain as lakes. Approximately 580 of the streams in the Mid-Atlantic Coastal Plain are acidic primarily due to acidic deposition. In the New Jersey Pine Barrens, for example, over 90 percent of the streams are acidic, which is the highest rate of acidic streams in the nation. Over 1,350 of the streams in the Mid-Atlantic Highlands (mid-Appalachia) are acidic, primarily due to acidic deposition.

The acidification problem in both the U.S. and Canada grows in magnitude if “episodic acidification” is taken into account. Episodic acidification refers to brief periods during which pH levels decrease due to runoff from melting snow or heavy downpours. Lakes and streams in many areas throughout the U.S. are sensitive to episodic acidification. In the Mid-Appalachians, the Mid-Atlantic Coastal Plain, and the Adirondack Mountains, many additional lakes and streams become temporarily acidic during storms and spring snowmelt. For example, approximately 70 percent of sensitive lakes in the Adirondacks are at risk of episodic acidification. This amount is over three times the amount of chronically acidic lakes. In the mid-Appalachians, approximately 30 percent of sensitive streams are likely to become acidic during an episode. This level is seven times the number of chronically acidic streams in that area. Episodic acidification can cause “fish kills.”

Emissions from U.S. sources also contribute to acidic deposition in eastern Canada, where the soil is very similar to the soil of the Adirondack Mountains, and the lakes are consequently extremely vulnerable to chronic acidification problems. The Canadian government has estimated that 14,000 lakes in eastern Canada are acidic.

Effects on Fish and Other Aquatic Organisms

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Acid rain causes a cascade of effects that harm or kill individual fish, reduce fish population numbers, completely eliminate fish species from a water body, and decrease biodiversity. As acid rain flows through soils in a watershed, aluminium is released from soils into the lakes and streams located in that watershed. So, as pH in a lake or stream decreases, aluminium levels increase. Both low pH and increased aluminium levels are directly toxic to fish. In addition, low pH and increased aluminium levels cause chronic stress that may not kill individual fish, but leads to lower body weight and smaller size and makes fish less able to compete for food and habitat.

Some types of plants and animals are able to tolerate acidic waters. Others, however, are acid-sensitive and will be lost as the pH declines. Generally, the young of most species are more sensitive to environmental conditions than adults. At pH 5, most fish eggs cannot hatch. At lower pH levels, some adult fish die. Some acid lakes have no fish. The chart below shows that not all fish, shellfish, or the insects that they eat can tolerate the same amount of acid; for example, frogs can tolerate water that is more acidic (i.e., has a lower pH) than trout.

Effects on Ecosystems

Together, biological organisms and the environment in which they live are called an ecosystem. The plants and animals living within an ecosystem are highly interdependent. For example, frogs may tolerate relatively high levels of acidity, but if they eat insects like the mayfly, they may be affected because part of their food supply may disappear. Because of the connections between the many fish, plants, and other organisms living in an aquatic ecosystem, changes in pH or aluminium levels affect biodiversity as well. Thus, as lakes and streams become more acidic, the numbers and types of fish and other aquatic plants and animals that live in these waters decrease.

Effects on Soils

Increasing amounts of acids can "mobilize" aluminium ions which are normally present in an insoluble nontoxic form of aluminium hydroxide. It appears that when the soil pH dips to 5 or lower, aluminium ions are dissolved into the water and become toxic to plants. Aluminium ions cause a stunting of the root growth and prevent the roots from taking up calcium. The result may be the overall slowing of the growth of the entire tree.

Lower soil pH and aluminium mobilization can reduce populations of soil microorganisms. Soil bacteria have the job of breaking down the dead and decaying leaves and other debris on the forest floor. The effect of this action is to release nutrients such as calcium, magnesium, phosphate, nitrate, and others. Low pH and high aluminium ion concentrations inhibit this process.

Higher amounts of acids can mobilize other toxic metals from the insoluble to the soluble ion forms in the same fashion as aluminium.The toxic metals include lead, mercury, zinc, copper, cadmium, chromium, manganese, and vanadium.

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These may all contribute to slow the growth of a tree. In addition, this combination of toxic metals may also adversely affect the growth of soil bacteria, mosses, algae, fungi, and earthworms.

Effects on the Forest Floor

A spring shower in the forest washes leaves and falls through the trees to the forest floor below. Some trickles over the ground and runs into streams, rivers, or lakes, and some of the water soaks into the soil. That soil may neutralize some or all of the acidity of the acid rainwater. This ability is called buffering capacity, and without it, soils become more acidic. Differences in soil buffering capacity are an important reason why some areas that receive acid rain show a lot of damage, while other areas that receive about the same amount of acid rain do not appear to be harmed at all. The ability of forest soils to resist, or buffer, acidity depends on the thickness and composition of the soil, as well as the type of bedrock beneath the forest floor. Midwestern states like Nebraska and Indiana have soils that are well buffered. Places in the mountainous northeast, like New York's Adirondack and Catskill Mountains, have thin soils with low buffering capacity.

Effects on Harms Trees

Acid rain does not usually kill trees directly. Instead, it is more likely to weaken trees by damaging their leaves, limiting the nutrients available to them, or exposing them to toxic substances slowly released from the soil. Quite often, injury or death of trees is a result of these effects of acid rain in combination with one or more additional threats.

Scientists know that acidic water dissolves the nutrients and helpful minerals in the soil and then washes them away before trees and other plants can use them to grow. At the same time, acid rain causes the release of substances that are toxic to trees and plants, such as aluminium, into the soil. Scientists believe that this combination of loss of soil nutrients and increase of toxic aluminium may be one way that acid rain harms trees. Such substances also wash away in the runoff and are carried into streams, rivers, and lakes. More of these substances are released from the soil when the rainfall is more acidic.

However, trees can be damaged by acid rain even if the soil is well buffered. Forests in high mountain regions often are exposed to greater amounts of acid than other forests because they tend to be surrounded by acidic clouds and fog that are more acidic than rainfall. Scientists believe that when leaves are frequently bathed in this acid fog, essential nutrients in their leaves and needles are stripped away. This loss of nutrients in their foliage makes trees more susceptible to damage by other environmental factors, particularly cold winter weather.

Effects on Other Plants

Acid rain can harm other plants in the same way it harms trees. Although damaged by other air pollutants such as ground level ozone, food crops are not usually seriously affected because farmers frequently add fertilizers to the soil to replace nutrients that

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have washed away. They may also add crushed limestone to the soil. Limestone is an alkaline material and increases the ability of the soil to act as a buffer against acidity.

Effects on Human Health

Acid rain looks, feels, and tastes just like clean rain. The harm to people from acid rain is not direct. Walking in acid rain, or even swimming in an acid lake, is no more dangerous than walking or swimming in clean water. However, the pollutants that cause acid rain—sulphur dioxide (SO2) and nitrogen oxides (NOx)—do damage human health. These gases interact in the atmosphere to form fine sulphate and nitrate particles that can be transported long distances by winds and inhaled deep into people's lungs. Fine particles can also penetrate indoors. Many scientific studies have identified a relationship between elevated levels of fine particles and increased illness and premature death from heart and lung disorders, such as asthma and bronchitis.

Based on health concerns, SO2 and NOx have historically been regulated under the Clean Air Act, including the Acid Rain Program. In the eastern U.S., sulphate aerosols make up about 25 percent of fine particles. By lowering SO2 and NOx emissions from power generation, the Acid Rain Program will reduce the levels of fine sulphate and nitrate particles and so reduce the incidence and the severity of these health problems. When fully implemented by the year 2010, the public health benefits of the Acid Rain Program are estimated to be valued at $50 billion annually, due to decreased mortality, hospital admissions, and emergency room visits.

Decreases in NOx emissions are also expected to have a beneficial impact on human health by reducing the nitrogen oxides available to react with volatile organic compounds and form ozone. Ozone impacts on human health include a number of morbidity and mortality risks associated with lung inflammation, including asthma and emphysema.

Acid rain is also believed to contribute to human respiratory diseases such as bronchitis and asthma. The affect of acidic pollution causes an increase in the frequencies of colds, allergies, and coughs in children. It is also the possibility that acid rain plays a role in Alzheimer's disease because toxic metals such as mercury and aluminium are released into the soil by acid rain. These toxic metals then become a part of the food supply of humans and have this horrible affect. Not only does acid rain contribute to damaging the environment but also to our lives as humans.

Effects on Buildings

Acids have a corrosive effect on limestone or marble buildings or sculptures. It is well established that either wet or dry deposition of sulphur dioxide significantly increases the rate of corrosion on limestone, sandstone, and marble.

Sulphur dioxide plus water makes sulphurous acid

SO2 + H2O --> H2SO3

Sulphur trioxide plus water makes sulphuric acid

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SO3 + H2O --> H2SO4

The sulphuric acid then further reacts with the limestone in a neutralization reaction.

Limestone: CaCO3 + H2SO4 --> CaSO4 + H2CO3

H2CO3 --> CO2 gas + H2O

The calcium sulphate is soluble in water and hence the limestone dissolves and crumbles.

Effects on Sculptures

There are many examples in both the U. S. and Europe of the corrosive effects of acid rain on sculptures. Many sculptures have been destroyed; a few have been preserved by bringing them inside.

The following are examples of endangered heritage sculptures:-

LESHAN GIANT BUDDHA, MOUNT EMEI (China, Buddhist)

Towering above the sheer river gorges of China’s Sichuan province, Mount Emei, one of the “Four Sacred Buddhist Mountains of China”, represents the main seat of Chinese Buddhism. It is home to the country's first Buddhist temple, built in the 1st century C.E., and contains numerous other temples, monasteries and religious shrines, including the 8th century Leshan Giant Buddha. This Tang Dynasty-era masterpiece is the world's largest Buddhist statue, reaching an awe-inspiring 71 meters in height and is 28 meters in width. Carved out of a face of a sandstone cliff facing Mount Emei, the Leshan Giant Buddha is surrounded by spectacularly lush and breathtaking subtropical and subalpine forests, and rests atop the confluence of three major rivers, the Minjiang, Dadu, and Qingyi. This site is a place of invaluable religious, artistic and natural significance.

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Leshan Buddha in China, 2005, sandstone has blackened and corroding due to the acid rain.

The Leshan Buddha has fallen victim to pollution emanating from unbridled development in the region. In this case, the culprit has been determined to be the growing number of coal fired power plants located near the Giant Buddha, specifically, the toxic gases that their smokestacks spew into the air; these eventually return to the earth as acid rain. Over time, the Buddha's nose has turned black and the curls of his hair have begun to fall from his head. The local government has shut down several factories and power plants in close proximity to the Leshan Giant Buddha, which has stopped the blackening of his face from soot; however, acid rain continues to compromise the structural integrity of this masterpiece. The Leshan Giant Buddha, which was designed carefully to survive millennia of floods and earthquakes, is now at high risk of rapid deterioration from the unbridled pace of industrial development in western China.

ACROPOLIS OF ATHENS (Greece, Ancient Greek)

While there are many Acropolises in Greece, it is the Acropolis of Athens that is, without question, the most quintessentially important monument that carries the name; indeed, when historians refer to simply “the Acropolis”, it is the one in Athens that is being referenced. Located atop a flat rock rising 150 meters above the city of Athens, its three hectares of standing monuments from the Classic Periclean period (460-430 BCE) include the Parthenon, the Propylea, and the Erechtheum, as well as a few earlier Mycenean edifices such as the Cyclopean Circuit Wall that helped to defend the Acropolis from numerous invasions over the centuries. As the foundational center for Golden Age Athens and its way of thought, the Parthenon is widely considered to be the crucible of democracy and Western culture as we know it.

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Hadrian's Arch at the Acropolis, Athens, 2005, marble has blackened and corroding due to the formation of acid rain.

In recent decades, as Greece has experienced substantial economic expansion and development, pollutants and heavy vehicle emissions from the booming modern city of Athens have contributed to acid rain in the region. The monumental and sculptural stone of choice for the ancient Greeks, marble, is highly susceptible to heavy surface degradation from even low levels of acid rain. The Parthenon’s magnificent marble relief frieze panels, for instance, have been chemically transformed by acid rain into soft gypsum. As details are lost and the chemical transformation soaks deeper into the marble on these vital monuments, pieces of them have begun to crack and fall off, with structural collapse a possibility in the not-so-distant future. Further complicating the situation is the seismically-active nature of the region, as earthquakes would have a far greater effect on marble constructions that have slowly transformed into gypsum than with unaltered marble.

TAJ MAHAL (India, Mughal Islam)

Located in Agra, India, the Taj Majal is a huge mausoleum built between 1631 and 1648 in the Mughal architectural style, combining elements of Turkish, Indian, Persian, and Islamic design. Considered to be the penultimate masterpiece of Islamic architectural art in India, it was built by Shah Jahan for his wife Mumtaz Mahal, and both are interred in it in a simple crypt.

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Taj Mahal, India, 2004, enveloped in smog.

The Taj Mahal is India’s preeminent tourist destination, attracting between two and four million visitors annually. In an effort to control the deleterious effects of pollution, tourist traffic is not allowed near the site, with most visitors riding in by electric bus from nearby car parks. This has not, however, slowed down the degradation of the Taj Mahal’s marble facades from acid rain generated from local foundries and an oil refinery. The once brilliant-white Taj has been losing its luster, dulling into a sickly pale shade.

DAMPIER ROCK ART COMPLEX (Australia, Australian Aboriginal)

The Dampier Archipelago, located in north-western Australia and stretching into the Indian Ocean from the Burrup Peninsula, is home to a magnificent collection of Aboriginal petro glyphs carved in rock faces and outcroppings. With around a million carvings across 400 square kilometres, these engravings constitute the largest corpus of rock art in the world. Some of the most ancient carvings date to tens of thousands of years into the past, when people first settled Australia, and depict sacred spirits, rituals, and animals – including several that are extinct (Tasmanian Tigers) or are no longer found in the region (Emus).

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Iron Mining, Dampier, 2003. This mine directly abuts important rock art sites, and produces emissions that contribute heavily to acid rain that is degrading them.

The Burrup Peninsula’s rock art sites have been listed as endangered by the National Trust of Australia, but industrial expansion since 1963 across more than 25% of the rock art area has posed severe threats to the site. Much of the heaviest (mining and petrochemical) industry is located immediately adjacent to some of the most sensitive collections of artwork. Acid rain from this has begun to erase many of the carefully, but often shallowly, engraved rock surfaces, and studies by archaeologists and geologists have postulated that most of the rock art will disappear completely by the middle of the 21st century.

LONGMEN GROTTOES (China, Buddhist)

The Longmen Grottoes are arguably the most famous ancient sculptural site in China. Located in Henan Province and positioned on two opposing bluffs above the Yi River, most of the artwork is Buddhist in nature and dates to the late Northern Wei and Tang Dynasties (316-907 AD). 2345 niches were carved from the rock, densely worked over the space of approximately a kilometre to the north and south, and they house more than 100,000 statues (also carved from the rock). Accompanying inscriptions bear more than 300,000 Chinese characters and are a treasure trove of historical and linguistic data. The Longmen Grottoes are a masterpiece of Buddhist art and are considered one of the world`s most important sculptural sites.

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Affected areas

Places with significant impact by acid rain around the globe include most of Eastern Europe from Poland northward into Scandinavia, the eastern third of the United States, and south-eastern Canada. Other affected areas include the south-eastern coast of China and Taiwan.

Prevention methods

Technical solutions

Many coal-burning power plants use Flue gas desulfurization (FGD) to remove sulphur-containing gases from their stack gases. For a typical coal-fired power station, FGD will remove 95 percent or more of the SO2 in the flue gases. An example of FGD is the wet scrubber which is commonly used. A wet scrubber is basically a reaction tower equipped with a fan that extracts hot smoke stack gases from a power plant into the tower. Lime or limestone in slurry form is also injected into the tower to mix with the stack gases and combine with the sulphur dioxide present. The calcium carbonate of the limestone produces pH-neutral calcium sulphate that is physically removed from the scrubber. That is, the scrubber turns sulphur pollution into industrial sulphates.

In some areas the sulphates are sold to chemical companies as gypsum when the purity of calcium sulphate is high. In others, they are placed in landfill. However, the effects of acid rain can last for generations, as the effects of pH level change can stimulate the continued leaching of undesirable chemicals into otherwise pristine water sources, killing off vulnerable insect and fish species and blocking efforts to restore native life.

Vehicle emissions control reduces emissions of nitrogen oxides from motor vehicles.

International treaties

A number of international treaties on the long range transport of atmospheric pollutants have been agreed for example, Sulphur Emissions Reduction Protocol under the Convention on Long-Range Tran boundary Air Pollution. Canada and the US signed the Air Quality Agreement in 1991. Most European countries and Canada have signed the treaties.

Emissions trading

In this regulatory scheme, every current polluting facility is given or may purchase on an open market an emissions allowance for each unit of a designated pollutant it emits. Operators can then install pollution control equipment, and sell portions of their emissions allowances they no longer need for their own operations, thereby

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recovering some of the capital cost of their investment in such equipment. The intention is to give operators economic incentives to install pollution controls.

The first emissions trading market was established in the United States by enactment of the Clean Air Act Amendments of 1990. The overall goal of the Acid Rain Program established by the Act is to achieve significant environmental and public health benefits through reductions in emissions of sulphur dioxide (SO2) and nitrogen oxides (NOx), the primary causes of acid rain. To achieve this goal at the lowest cost to society, the program employs both regulatory and market based approaches for controlling air pollution.

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Reference Acid Rain Effects on Buildings

http://www.elmhurst.edu/~chm/vchembook/196buildings.html Top 5 Endangered Heritage Site

http://archive.cyark.org/top-5-endangered-heritage-sites-acid-rain-blog Effect of Acid Rain – Human Health

http://www.epa.gov/acidrain/effects/health.html Acid Rain – Soil Interactions

http://www.elmhurst.edu/~chm/vchembook/196soil.html Effects of Acid Rain – Forests

http://www.epa.gov/acidrain/effects/forests.html Nitrous Oxides Sources

http://www.ghgonline.org/nitrousagri.htm#direct Acid Rain and Human Health

http://hey-ralph911.tripod.com/id4.html Carbon Monoxide

http://www.epa.gov/oms/invntory/overview/pollutants/ carbonmon.htm#onroad

Sources of Lead http://www.health.state.ny.us/environmental/lead/sources.htm

Environmental Facts – CFCs http://www.environment-agency.gov.uk/business/topics/pollution/304.aspx

All About Pollutants http://www.epa.gov/

Ontario – Sulphur dioxide http://www.airqualityontario.com/science/pollutants/sulphur.cfmAll

About Acid Rain http://environment.nationalgeographic.com/environment/global-warming/acid-

rain-overview/ http://library.thinkquest.org/CR0215471/acid_rain.htm http://en.wikipedia.org/wiki/Acid_rain

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