It wreaked havoc in Europe. Now scientists are worried that acid rain may soon acquire grave proportions in India. Acid rainwater may cause irreparable damage to the country's biodiversity, crop yields and the economy. Will we be prepared for it when disaster strikes?
Acid rain arriving soon in India
When it rains it burns
Acid rain has already been reported in some parts of India, and the situation is likely to get worse
India faces an increasing threat from acid rain -- earlier believed to be the scourge of the West. The large-scale industrial growth and reliance on the use of coal and crude oil distillates like diesel have led to acidification of the atmosphere.The burning of fossil fuels is mainly responsible for creation of sulphur dioxide ( so 2 ) and oxides of nitrogen ( no x ) which lead to the formation of acid rain. Automobile exhaust fumes are partly to blame, but the worst culprits are coal-burning thermal power plants and the steel industry. Already, a low pH has been observed at Chembur, Maharashtra and Delhi. This is the conclusion of a study conducted by Manju Mohan and Sanjay Kumar of the Centre for Atmospheric Sciences, Indian Institute of Technology ( iit ), New Delhi.
The phenomenon of rain is caused when heat from the Sun's rays on the surface of seas, lakes and rivers induces evaporation. The water vapour formed in the process rises to a height where it condenses into moisture. If ambient conditions prevail it comes down as rain. But in the case of acid rain, water vapour reaches the atmosphere, condenses, and reacts with atmospheric gases like so 2 and no x . When it rains, these atmospheric pollutants are deposited on the soil, vegetation, surface water or reservoirs. The deposition ultimately results in damage because of the acidity of the pollutants (see chart: What goes up must come down ).
The problem is very real in the sub-continent. India enjoys the dubious distinction of releasing the maximum pollutants in the atmosphere after China. Total sulphur emissions are expected to rise from 4,400 kilotonnes (kt) in 1990 to 6,500 kt in 2000, 10,900 kt in 2010 and 18,500 in 2020. It is, therefore, not surprising that low pH levels have been reported from Delhi, Uttar Pradesh, Maharashtra, Madhya Pradesh, Tamil Nadu and even the Andaman Islands. While this will not result in acid rain, the stage has been set for it and if conditions worsen like the setting up of a highly polluting thermal power plant in the vicinity or an industrial estate there may be acid rain. After analysing data from 10 Indian Background Air Pollution Monitoring Stations ( bapmons ), scientists have confirmed that rain in and around these cities is getting increasingly acidic in nature.
The bapmons data collected during 1974-1984 shows that a few areas are already under stress conditions. During two decades, the acidic content of rain in Delhi increased, which means its pH level decreased from 7.0 (1965) to 6.1 (1984), and in nearby Agra from 9.1 (1963) to 6.3 (1984). The data also showed that pH levels in the Andaman Islands fluctuated between 5.6 and 8.9. Acidity and alkalinity are measured on the pH scale from 0 to 14. Normal water is 7 on the scale. Decreasing values on the pH scale denotes increasing acidity and, conversely, higher values show increasing alkalinity. A value below 5.6 denotes acid rain (see graph: Scale of acidity ).
C K Varshney, professor, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, warns 'Acid rain may cause irreparable damage to the country's biodiversity and even damage the food chain.'
Moreover, the use of diesel is causing a high amount of sulphur and nitrogen emissions in the metros. Indian diesel has a sulphur content of 0.5 per cent by weight. Delhi and Agra are supplied with diesel that has a lower sulphur content. "But even this is far higher than sulphur levels in diesel used in countries like Sweden (0.001 per cent). Swedish diesel is 250 times cleaner. It means that with the rising number of diesel vehicles, the government's objective to bring down sulphur emissions may not be achievable," says H B Mathur, professor emeritus, Delhi College of Engineering. "If the government continues to encourage diesel usage, the prediction made by the iit study may well come true," adds K P Nyati, head (environmental division), Confederation of Indian Industries ( cii ), New Delhi.
The only good news for India is that chances of acid rain occuring are unlikely. This is because tropical climatic conditions and predominantly alkaline-rich soils of the country have a neutralising effect on the pollutants, says R N Gupta, director, Environmental Meteorology Unit, Indian Meteorological Department ( imd). As dust particles in the country are alkaline in nature, acid rain-causing gases such as so 2 and no x get neutralised.
But there is the possibility of the phenomenon occurring in the Northeast and some parts of south India, he says. The imd has, however, not confirmed these findings.
Scientists became aware of acid rain more than a century ago
A cid rain is not a recent phenomenon. The term was first coined in 1852 by a chemist, Robert Angus Smith. The 35-year-old chemist, while studying the quality of air in and around his home town Manchester, England, found local rainfall to be unusually acidic. He suspected a connection between this occurrence and sulphur dioxide emissions when coal was burnt by local factories. He even noticed that the acid in the air was causing textiles to lose their colours and metals to corrode. The air over Manchester was partly cleaned by building tall chimneys at power stations and factories which release pollutants high into the air. These chimneys improved the air quality locally by dispersing the pollutants, but they were only blown across into neighbouring countries.
The uk 's early awareness of pollution was related to its early industrialisation. But even in less industrialised parts of Europe, observers were beginning to worry about the effects of smoke from coal. In 1881, Norwegian scientists observed polluted snowfall and attributed it to a large town or industrial district in England. Just before World War I, mass deaths began to occur among fish in the rivers of southern Norway. Lakes, too, began losing their fish populations. But it was only in the 1950s that the link with acid rain was established.
In his book Acid Earth , John McCormick recounts that research in Austria and England from 1911-1919 showed that rain with dilute sulphuric acid inhibited plant growth. In 1924, a farmer from Manchester even sued the power station at Barton in England for compensation, arguing that sulphur emissions were damaging his crops. His claim, however, was rejected by the House of Lords.
Today, industrial regions suffer much more acidic fall-out than they did before the Industrial Revolution. In 1968, scientists had pointed out that rainwater was becoming increasingly acidic with each passing year. Acid rain has continued to spread and today covers nearly the whole of Europe, Canada, usa and the Scandinavian countries. By 1982, there were 18,000 acidified lakes in Sweden (twice as many as in 1975). The lakes in the region were previously known for their diversity of flora and fauna. Acid-sensitive species disappeared from roughly 120,000 square kilometres (sq km) or about 40 per cent of the country's lakes.
According to John McCormick, studies conducted between 1985 and 1990 in southern Norway, revealed that fish populations had been lost in 2,650 lakes over an area of 33,000 sq km. Salmon had disappeared from most of southern Norway's rivers and brown trout populations had declined.
Many lakes and streams in the us and Canada are extremely acidified because they rest atop soil with a limited capacity to neutralise compounds (called buffering capacity). The us National Surface Water Survey found that acid rain had affected 75 per cent of the lakes and about half the streams. In north America, electricity generation accounts for about 70 per cent of annual so 2 and 30 per cent no x emissions.
In Canada, over 40,000 lakes have been permanently polluted by acid rain. Scientists from Norway and Sweden claim that acid rain, mainly brought by the winds blowing from heavily industrialised Europe, has caused at least 15 per cent reduction in timber growth. Increased acidity affects marine life, which, in turn, effects humans and animals living off marine life. Acidity in water affects the egg-producing ability of fish and decomposition of organic matter slows down. Human beings who live by eating fish from these lakes are also affected (see box: The toll rises ).
Acid rain has been the bone of contention between many Western countries because winds carry the pollutants across international boundaries. Sulphur and nitrogen compounds emitted by burning fossil fuels can be blown thousands of kilometres to cause acid rain in countries far from the points of origin. A report prepared by the us Environment Protection Agency ( epa ) says the large-scale weather systems often transport airborne acid pollutants thousands of kilometres from their source before they descend as rain. Thus, pollutants emitted from sources in the industrial heartland of the midwestern states of the us and central Canada regularly fall on the comparatively less polluted areas of northeastern us and southeastern Canada, it says.
"It is hard to predict where it can occur," says Nyati.
It has been the cause of a long-standing disagreement between the us and Canada, and the Scandinavian and western and central European countries. While Canada sends half-a-million tonnes of dangerous emissions to usa , it receives almost two million tonnes in return. Norway and Sweden claim that they are being bombed by the uk and what was formerly West Germany. Similar charges have been made by France and Germany against each other.
In January 1983, the us department of justice announced that two Canadian-produced films about acid rain, along with another film on nuclear war, were political propaganda, and may no longer be shown to us audiences without a disclaimer noting that the films were not endorsed or approved by the us government. Canadians were worried that acid rain was a direct threat to their primary industries -- forestry, freshwater fisheries and tourism. Acid rain soured relations between the two countries for a number of years.
According to the New York Times , when people in the us , think of the ravages of acid rain, they tend to think mainly of dead and dying watersheds in the northeastern part of the country, particularly those in New York's Adirondack Mountains where hundreds of highly acidified lakes and streams can no longer sustain aquatic life. But, this year, an exhaustive federal study has concluded that acid rain spread its poisons far and wide, damaging sensitive watersheds in the Southeastern region and in ecologically significant areas of western usa like the Sierra Nevada, the Cascade Range and some parts of the Rocky Mountains.
These findings submitted by a federal panel -- the National Acidic Precipitation Assessment Program -- are disturbing. But they could also recruit new allies to the unfinished struggle against acid rain. In 1990, the us Congress confronted the problem for the first time, ordering coal-fired utilities and other industries to halve their emissions of sulphur dioxide, the main cause of acid rain, over the next decade. Nitrogen was also regulated by the 1990 law because it causes smog, a serious health hazard. But not until the mid-l990s was nitrogen recognised as a significant contributor to acid rain as well.
The federal panel report shows that emissions of sulphur dioxide have declined sharply and at relatively low costs, due mainly to the 1990 law. The report also suggests that the law and subsequent regulations aimed at reducing oxides of nitrogen from power plants should have a positive effect, though the evidence so far is sketchy. But the problem is far from solved, and in some areas may be much worse than anyone thought. If present trends continue, the report warns, about half the Adirondack's 2,800 lakes and streams will be too acidic to support life by the year 2040. The San Gabriel Mountains near Los Angeles are 'saturated' with nitrogen meaning that excess nitrogen is seeping into nearby lakes and streams. Watersheds in other western ecosystems are similarly afflicted.
In asia as well, the situation is about to reach alarming proportions. Given the fact that the two most populous countries of the world -- China and India -- have substantial reserves of coal, the continent remains a region where coal use is expected to grow substantially in the coming decades. Fortunately, for India, the sulphur content of coal found in the country is consistently low. But this is not the case with China. There are several sources of anthropogenic sulphur dioxide emissions, including power generation and transport and even household energy use for cooking, using a variety of fuels. In fact, the Rains-Asia model, on which the iit scientists worked, indicates the possibility of a 315 per cent increase in so 2 emissions over present levels in India by the 2020.
They have reported that ecosystems exceeding the critical load will rise from zero to 15 per cent between 1990 and 2010. Otherwise, it could reach 50 per cent. According to Mohan and Kumar areas exceeding the critical load are mainly located in southeast Bihar, West Bengal and Delhi. Critical load is the maximum deposition of pollutants that will not damage the ecosystem. It is calculated on the basis of the ability of a system to buffer the acidity due to the supply of acidic compounds and varies from place to place.
A World Bank and Asian Development Bank-sponsored study in 1995 showed that areas in Asia with critical loads of up to 320 milligrammes per square metre per year are located in south China, southeast Thailand, Cambodia, and south Vietnam. A similar study by the funding bodies five years earlier had shown these areas to be located in southeast China, northeast India, Bangladesh, Thailand, parts of Indonesia, South Korea, southern Japan and small parts of the Philippines (see graph: Dangerously high ).
According to researchers at the Tata Energy Research Institute ( teri ), by the year 2020, the energy demand in India is expected to increase by 300 per cent from the present level. Their predictions for the same year for different countries of Asia region using the Rains-Asia model shows a grim picture. Many areas in the region will cross the critical loads of sulphur deposition. Except Pakistan, the western and central parts of India, western China, Myanmar and parts of Indonesia, the rest of the continent is expected to be severely affected. This means areas which will experience sulphur deposition levels far in excess of their critical loads include southern and eastern parts of China, parts of northern and central Thailand, the Korean peninsula and large portions of north and eastern India and specifically Delhi, Agra, Chembur, Trombay, Thane, Ghatko-par, Belapur, Nagpur, Pune, Korba, Singrauli, Kodaikanal and Port Blair. Kodaicanal falls into the sensitive pH zone and is prone to environmental degradations and even acid rain. In areas where there is vegetation like pines, the soil is acidic and more susceptible to degradation than areas with alkaline soil (see maps: Areas at risk and table: Fluctuating trends ).
In some industrial hotspots of China, the sulphur deposition levels on land are as high as 18 grammes per square metre per year, which is many times above the critical level. By 2020, virtually all of China's eastern part and large regions in India, including the capital of Delhi and nearby Agra will have to bear sulphur deposition levels between two and five grams per square metre, as per teri estimates.
John McCormick in his book Acid Earth says that coal-fired thermal power plants provide nearly 65 per cent of India's electricity. Although they use low-sulphur coal, the older plants are fitted with mechanical dust collectors that generally operate at about 70 per cent efficiency. Newer plants have electrostatic precipitators which can remove up to 99 per cent of dust if properly maintained. But breakdowns regularly lead to pollution. For example, a breakdown of precipitators in the Bhatinda power station in the Punjab in the early 1980s resul-ted in 1,200 tonnes of fly ash being emitted into the atmosphere every year. In 1982, India Today reported that the town of Bhatinda (which received no power itself from the plant) lay under 'a permanent blanket of smoke; fly ash coats every surface and a good deep breath is likely to wind up a racking cough'.
In The State of India's Environment: A Citizen's Report , the Delhi-based Centre for Science and Environment ( cse ) warned in 1983 that air pollution, "after engulfing the large cities of India...
has begun to hurt the residents of small towns and once sleepy villages where thermal power stations and large industries are now being located." cse observed that while urban communities have pressure groups and officials to whom protests can be made, effective protest in villages can take longer to emerge.
How safe is the Taj?
The problems facing the Taj Mahal illustrate the threat to India's cultural heritage. In 1982, a major oil refinery was opened outside Mathura city, just 40 km from the Taj in Agra, and upwind from other monuments in Fatehpur-Sikri, Mathura and Brindavan. The refinery processes more than 6 million tonnes of crude oil annually.
According to John McCormick there were fears from the outset that the pollution caused by the refinery would slowly destroy the Taj, although government officials denied the possibility. An Italian consultancy firm brought in to advise on the environmental consequences of the refinery concluded that so 2 emissions would be insufficient to damage the structure, and that existing discolouration of marble and sandstone in monuments in the vicinity was due to algae and fungi rather than pollutants. While scientists, environmen-talists and politicians grope with how to tackle the latest threat to the environment, there are fears about the gradual destruction of the Taj Mahal. John McCormick has also expressed concern over this. However, a book written by Delhi-based journalist Anil Maheshwari created a furore in 1996.
Maheshwari attempted to put at rest fears of damage to the monument from numerous polluting industries in and around Agra. In his book, he says the accusation the structure has turned yellow because of acid rain, formed by the presence of sulphur dioxide in the atmosphere, is 'incorrect'. He adds that even if it is assumed that acid rain occurs in Agra, it can never turn marble yellow. Marble tends to turn whiter when it comes in contact with sulphuric acid, even though the surface turns rough and flaky, he contends.
Maheshwari further states that given Agra's power situation most of the time this equipment will run on diesel generators which will exacerbate the situation. In a chapter titled Yellow Fever , he says a senior government official in the department of culture had communicated to the Vardarajan committee on the issue that - structurally - the monument was in a sound state of preservation and studies had confirmed the same.
However, Agra's pollution level have not displayed an ability to remain static for long. Although data published by the Uttar Pradesh Pollution Control Board ( uppcb ) shows a decline in spm levels in the city between 1991 and 1994, it has steadily increased since. Emissions from 70,000 generators used as a result of daily power cuts, increasing number of three-wheelers running on diesel and emissions from the refinery continue to be major sources of high levels of spm .
The closure of 212 coal-based industrial units in 1993 and relocation of a thermal power plant are possible reasons for the decline in spm levels between 1991 and 1994. But the reason for the increase of pollution from 1994 to 1996 are not clear. The blame lies partially with the increased use of generators due to power shortages following relocation of the power plant (Refer to 'Death is in the air', Down To Earth , Vol 6, No 12).
A positive step to cut pollution levels was the Supreme Court's landmark decision which ordered the reduction of sulphur content in diesel sold in the Taj trapezium from 0.5 to 0.25 per cent. The region is a 10,400-sq km trapezium-shaped area covering the five districts of Agra.
Blackening the air
As energy requirements in India will grow rapidly in tune with the economy, coal dependence is expected to increase threefold over the current level of consumption, making the clouds of acid rain heavier over many highly sensitive areas in the country - the northeast, parts of Bihar, Orissa, West Bengal and the southern coastal areas. Already the soils of these areas have a low p h value, which acid rain will aggravate making it infertile and unsuitable for agriculture (see box: Deep impact ).
The green India 2047 project of teri has estimated that India is already losing between 11 per cent and 26 per cent of agricultural output on account of soil degradation. Acid rain would increase this figure significantly. The prospect of increasing consumption of coal in Asia will add insult to injury.
collected in 1974-84 from eight towns where monitoring stations are located
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