How Does Acid Rain Affect Lakes?

Acid rain is a product of the burning of fossil fuels and poses a threat to the ecosystems of streams and lakes. In particular, when certain levels of acidity are reached, fish and other aquatic life will die. Since all flora and fauna in a given ecosystem are interdependent, the effects of acidic water are far-reaching. Acid rain is worse in areas with dense populations and heavy industry, particularly the eastern United States.

Acid Rain

Atmospheric pollutants, particularly nitrogen oxide and sulfur dioxide from the burning of fossil fuels, cause precipitation to become acidic. These gases mix with water vapor and oxygen in the atmosphere to form nitric and sulfuric acids, which cause acid rain. This acidic precipitation lowers the pH level of water in streams and lakes, creating adverse effects. Acidic waters will also more readily absorb aluminum leeched from soil runoff, and the combination of aluminum and acidic water is especially harmful to many aquatic species.

Lakes and Acidity

Water pH is the amount of free hydrogen ions in a given sample, and the scale ranges from 0 to 14, with numbers below 7 being acidic. Each level down the scale represents a tenfold increase in hydrogen ions, so a pH of 5 has ten times more ions than a pH of 6. Normally, lakes will be neutral, pH levels between 6 and 8, but lakes with pH below 5 are considered acidic. In addition to acid rain, acidic rainfall leeching through soils that lack acid-buffering capability will eventually wind up in streams and lakes. Normally, lake water contains bicarbonates and other compounds that have the ability to buffer their pH levels, but acid rain in particular disrupts this ability.

Acid Rain and Aquatic Life

When an influx of acid rain reaches a certain threshold in a lake, it overcomes the lake’s ability to buffer acids. The lower pH levels in the water have a direct and primary effect on many of the various creatures that live within the lake ecosystem. Many species of fish, shellfish and other lake species such as snails and salamanders are adversely affected by acidic water. For example, a pH of 5 will kill fish eggs, and lower levels will kill adult fish. Not only does the low pH affect aquatic life, but it also affects the lives of terrestrial species and birds that feed on aquatic life.

Most Sensitive Regions

Given the adverse effects of acid rain on lake ecosystems, it is important to understand which areas are most at risk. Lakes in the northeast United States, Appalachian highlands, upper Midwest and the mountains of western North America are most prone to having pH levels below 5. In 2006, the National Atmospheric Deposition Program noted that acidic precipitation lower than pH 5 falls downwind of heavy industrial areas, and it is worst in the Ohio River Valley region of the upper Midwest. The pH of precipitation in this region can be at dangerously low levels below 4.3. The entire region east of the Mississippi River in the United States is especially vulnerable.

The Advantages of Acid Rain

Acid rain comes in the form of rain, fog, smog and dry depositions, and it harms forests, kills fish and erodes rocks and buildings. It is caused by excessive emissions of sulfur dioxide and nitrogen oxide compounds from industrial and natural sources. About two-thirds of sulfur dioxide and one-quarter of nitrogen oxides come from fossil-fuel-burning power plants. Some environmental studies indicate that the effects of acid rain are complex and include positive effects on global warming and improvement of forests.

Global Warming

Methane and carbon dioxide are major greenhouse gases that cause global warming. Methane, compared to carbon dioxide, is more potent. When compared by weight, methane has 20 times more of an impact on climate change than carbon dioxide does over a 100-year period, according to the U.S. Environmental Protection Agency. Methane is emitted from agricultural and industrial processes, but the largest source of methane entering the atmosphere is wetlands.

Suppressing Methane Production

About 22 percent of the human-enhanced greenhouse gas effect is due to methane. Microbes feeding on hydrogen- and acetate-containing vegetation in wetlands are natural contributors to total atmospheric methane. In a study of wetlands in Europe and North America, researchers at the Open University, U.K., found that sulfur compounds deposited by acid rain inhibited methane production by wetlands. The researchers found that methane production was significantly suppressed because sulfur-eating bacteria in wetland areas out-competed methane-emitting microbes. Sulfur compound deposition from acid rain can reduce methane production by up to 30 percent. In another study, the effects of acid rain on rice paddies were mimicked by adding small amounts of sulfate to the soil. Up to 24 percent of the methane was prevented from entering the atmosphere.

Forests

A 20-year-long study by scientists at Michigan Technological University School on the hardwood forests of Michigan found that acid rain, together with modest increases in temperature, makes forests more productive. Researchers measured nitrogen deposition by acid rain and found that trees store more carbon when the soil contains more nitrogen compounds, as long as there is enough moisture. Therefore, the increased growth rate and greater ability of trees to store carbon dioxide may offset some of the negative effects of acid rain on forests, such as damage to tree foliage.

Complex Effects of Acid Rain

Acid rain clearly has negative effects on the environment, but the beneficial effects of acid rain must enter into future predictions of its role in environmental damage and global warming. A computer model, created at NASA's Goddard Space Flight Center, predicts that the sulfur dioxide in acid rain will continue to suppress methane production by wetlands well into 2030. Although nitrogen oxide deposition by acid rain may have positive effects on forest trees, highly polluted acid rain damages trees and harms some animal species.

Natural Causes of Acid Rain

Acid rain is precipitation with a pH of less than 5.6. Its principal constituents are nitric and sulfuric acids formed by chemical reactions of nitrogen and sulfur oxides with water vapor in the atmosphere. Although associated mostly with industrial, vehicle and power generation emissions, these and other gases that react with water to make acid rain are also released by natural phenomena such as volcanic eruptions and biological processes.

Atmospheric Composition

The pH of rainwater in unpolluted regions is 5.6, making it a weakly acidic solution. A neutral solution has a pH of 7. Rainwater acidity is caused by the presence of carbon dioxide, nitric oxide and sulfur dioxide in the atmosphere. Carbon dioxide concentrations in the atmosphere are 335 parts per million compared with 0.01 ppm for nitric oxide and up to 0.01 ppm for sulfur dioxide. Carbon dioxide reacts with water vapor to produce carbonic acid. However, in pristine environments the natural rainwater pH may become more acidic, ranging between 4.5 and 5.6, because of the variability of naturally occurring sulfur and nitrogen oxides in the atmosphere.

Volcanic Eruptions

Volcanic eruptions release water vapor and gases such as carbon dioxide and monoxide, sulfur dioxide, hydrogen chloride, hydrogen sulfide, hydrogen fluoride, ammonia, methane and silicon tetrafluoride. These gases react with water vapor to precipitate as acid rain. Hydrochloric and hydrofluoric acids, together with other fluoride and chloride compounds, which build up in large concentrations in the vicinity of the eruption area, are poisonous to plants and animals, cause skin and eye irritations and can damage machinery. Sulfur dioxide from a volcano, together with aerosols, can rise 19 to 32 kilometers (12 to 20 miles) into the atmosphere and cause a global cooling effect by blocking solar radiation.

Lightning Strikes

Lightning is one of the major sources of localized atmospheric nitrogen, sulfur and carbon oxides. Lightning bolts reach temperatures of about 30,000 degrees Celsius (54,000 degrees Fahrenheit) and can transmit a current of up to 20,000 amps. This is powerful enough to cause nitrogen and oxygen in the atmosphere to react and create nitrogen oxide and nitrogen dioxide. The latter dissolves in water vapor to precipitate as weak nitric acid. Lightning also triggers wildfires that emit carbon and sulfur oxides into the atmosphere that in turn dissolve in water vapor and precipitate as carbonic and sulfuric acids.

Emissions from Vegetation

Terrestrial vegetation produces carbon dioxide as part of the transpiration process and when rotting on the ground. Aquatic plants and bacteria that exist in anaerobic -- oxygen-free -- conditions emit methane. Tropical and temperate forests emit isoprene, a biogenic volatile organic compound. Isoprene is oxidized in the troposphere and reacts with nitrogen oxides to produce ozone, organic nitrates and organic acids such as methacrylic and acrylic acids. These acids contribute to the acidification of rainwater.

10 Serious Effects of Air Pollution on the Environment

 The constant pollution of the air has very negative effects on nature and on human health. Those long-term and medium-term effects have become problems that are difficult to solve.

In this article, we are listing the main 10 negative effects that air pollution is causing worldwide:

Global Warming

Probably global warming is one of the most worrying effects for scientists and environmentalists. Global warming is a direct consequence of the greenhouse effect, which is produced by the high emission of CO₂ and methane into the atmosphere. Most of these emissions are produced by the industry, so this can be remedied by social responsibility and action by companies and factories.

Climate Change

Climate Change is another consequence of global warming. When the temperature of the planet increases, there is a disturbance in the usual climatic cycles, accelerating the changes of these cycles in an evident way.

Due to climate change, the mass of the poles is melting, and this is leading to flooding and the rising of sea levels.

Acid Rain

The gases emitted by industries, power plants, boilers, heating and transport are very toxic. Those gases include sulphur dioxide (SO₂) and nitrogen oxides (NOx) issued into the atmosphere that come from fossil fuels burning. When those substances accumulate in the atmosphere and react with water, they form dilute solutions of nitric and sulphuric acid, and  when those concentrations become rain, both the environment and surfaces suffer.

Smog effect

The smog effect or beret effect happens when there is a kind of dark fog concentrated over the cities and fields. That fog is a load of pollutants and can be of 2 types: sulphurous smog and photochemical smog, both dangerous and harmful to health. Both types of smog are a consequence of industrial and urban action. However, sulphurous smog has its origin mainly in the use of coal in many industrial processes. That has been reduced in the most advanced countries – nevertheless, there are still many developing countries that do not have treatment protocols for pollutants.

Deterioration of fields 

Acid rain, climate change and smog all damage the Earth surface. Contaminated water and gases seep into the earth, changing the composition of soils. That directly affects agriculture, changing crop cycles and the composition of the food we all eat.

Extinction of animal species

As the ice masses of the poles melt and sea levels rise, many animal species, whose survival depends on oceans and rivers, are threatened. Currents change, ocean temperatures change and migratory cycles change, and many animals are forced to seek food in environments unknown to them. Deforestation and poor soil quality also mean the disappearance of ecosystems and habitats. And definitively, an imbalance in the behavior of many wild species.

Respiratory health problems

It is probably one of the most obvious and worrying effects for human beings. Pollutants can cause respiratory illnesses and allergies ranging from coughs to asthma, cancer or emphysema.

Inhalation of toxic agents directly affects the lungs and other organs that make up the respiratory system. Also, poor oxygenation can lead to cardiovascular problems.

Deterioration in building materials

Air pollutants also deteriorate and change the constitution of building materials, so many buildings and infrastructure are weakened, eroded or destroyed at an accelerated rate over time.

Chemical Sensitivity

People develop intolerances and allergies to many agents present in the atmosphere and to other external agents that can go through due to the holes in the ozone layer. This is because there is a high concentration of chlorofluorocarbons that alter the thickness of the ozone layer.

Chlorofluorocarbons (CFCs) are released using aerosols, industrial refrigerants, solvents and other very harmful chemicals.

Skin Damage

Many of the chemical intolerances directly affect people’s skin. However, one of the worst damage is skin cancer. That disease in many cases develops from the direct incidence of ultraviolet light rays on the skin.

The ozone layer acts as a filter for those rays. If the ozone layer is thinner, the effectiveness of the filter decreases, letting rays pass, which are very harmful to humans.

 

All those important effects can increase if their causes are not rapidly acted upon. Most of them are the result of very intense, polluting and uncontrolled industrial activity.

Companies around the world have the responsibility to manage, treat and control the pollutants they emit into the atmosphere. Our health and avoiding the destruction of the environment depend on their response.

Effects of Acid Rain on Humans

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. The air pollution that causes acid rain is more damaging to human health. Sulfur dioxide and nitrogen oxides, the major sources of acid rain, can irritate or even damage our lungs.

The pollutants that cause acid rain can also reduce visibility, limiting how far into the distance we can see. The primary pollutants associated with acid rain and poor visibility are human-made sulfur dioxide emissions. These emissions form small sulfate particles, or aerosols, in the atmosphere. These aerosols reduce visibility by scattering light. Sulfate aerosols are the main cause of poor visibility in the eastern United States.

Nitrogen oxide emissions are also associated with the acid rain problem. They, too, can form aerosols in the atmosphere that significantly reduce visibility. Nitrate aerosols are often the main cause for poor visibility in the western United States where sulfur dioxide emissions and humidity are lower than in the east.

Making Acid in the Air

The final concentration of acids (mainly sulfuric acid, H₂SO₄ and nitric/nitrous acid, HNO₃/HNO₂) in precipition (acidity) is dependent on emissions of SO₂ and NO_x from sources, weather conditions andother chemicals present in the atmoshpere. The formation of sulfuric and nitric/nitrous acid in the atmosphere is a complex process involving several chemical reactions involving both solution and gas phase reactions.

SO₂

Gas phase	Solution phase
2SO2 + O2® 2SO3 very slow in the absence of a catalyst, therefore this is not a significant contributor	1) SO2 (aq)® H+ + HSO3- 2) HSO3- (aq)® H+ + SO32- The equilibrium concentraions for the above reactions are dependent upon such things as pH, droplet size, the "sticking coefficient" for SO2 on water, etc.
2SO3 + H2O® H2SO4 occurs quickly, therefore any formation of SO3 in the moist atmosphere is assumed to lead to the formation of sulfuric acid	1) HSO3- + H2O2® A- + H20 2) A- + H+® H2SO4 The dominant oxidation process occurs by hydrogen peroxide (formed in the gas phase from free radicals). The reaction involves the formation of an intermediate (A-), possibly a peroxymonosulfurous acid ion
1) HSO3- + H2O2® A- + H20 2) A- + H+® H2SO4 The dominant oxidation process occurs by hydrogen peroxide (formed in the gas phase from free radicals). The reaction involves the formation of an intermediate (A-), possibly a peroxymonosulfurous acid ion

NO_x

Gas Phase	Aqueous Phase
HO + NO2 (+M)® HONO2(+M) the principal contributor to the formation of nitric acid is the reaction with hydroxy radicals. These radicals are highly reactive and abundant in the atmosphere.	1. 2NO2(g) + H2O(l)® 2H+ + NO3- + NO2- 2. NO(g) + NO2(g) + H2O(l)® 2H+ + 2NO2- 3. 3NO2(g) + H2O(l)® 2H+ + 2NO3- + NO(g) Equilibria of three reactions define the aqueous oxidation of Nox and depend on the partial pressures of NOx present in the atmosphere, temperature, humidity and the low solubility of NOx.

What Region of the United States Is Most Affected by Acid Rain?

Acid rain didn't become an environmental problem until the burning of large quantities of fossil fuels during the industrial age. Some acid rain occurs naturally, but sulfur dioxide and nitrogen oxide emissions from smokestacks combine with rain to make sulfuric and nitric acid in amounts that harm the environment. The region of the United States most harmed by acid rain is the East Coast, including the Appalachian Mountains and the Northeast.

Lakes and Streams

In a study of the nation's lakes and streams that show acidic conditions, the National Surface Water Survey found that acid rain caused the acidity in 75 percent of the lakes and about 50 percent of the streams. Greatest acidity occurred along the Atlantic coast, where waters have naturally higher acidity to begin with. The highest rate of stream acidity, over 90 percent, occurs in the New Jersey Pine Barrens region. Little Echo Pond in Franklin, New York, had one of the most acidic conditions, according to the study, with a pH of 4.2.

Forests and Soils

Acid rain degrades soils by washing away chemicals such as calcium and magnesium, which buffer acidity and provide essential nutrients to plants. Acidity also releases potentially toxic dissolved aluminum into water. Appalachian forests from Maine to Georgia are particularly affected. Trees usually don't die outright but are weakened and more susceptible to pathogens, insects, drought or extreme cold. Scientists expect that the U.S. Environmental Protection Agency's Acid Rain Program, which reduces sulfur dioxide emissions, will significantly reduce acidification along the East Coast.

What Place in the World Receives the Most Acid Rain?

Acid rain is responsible for severe environmental destruction across the world and occurs most commonly in the North Eastern United States, Eastern Europe and increasingly in parts of China and India. According to the Environmental Protection Agency (EPA) acid rain can be particularly damaging to the young from many species of plant and wildlife.

What is Acid Rain?

Nitrogen oxide and sulfur dioxide are polluting byproducts of soft-coal-burning power plants and factories, and are the main culprits in the production of acid rain. When these chemicals combine with water and particulates in the atmosphere, the result is precipitation, which includes rain, snow and fog, laden with nitric and sulfuric acids, otherwise known as acid rain.

The Black Triangle

Covering areas of the Czech Republic, Germany and Poland, the Black Triangle is an area that received heavy acid rain throughout the 1970s and 80s. In parts of the Black Triangle, entire forests were dead or dying and even railroad tracks were being corroded by the acidic precipitation. The emissions of coal-burning factories in Eastern Europe came under strict regulation by the Geneva Convention of 1979 to prevent further acid rain pollution, a measure that has been successful in significantly reducing acid deposition in the region.

Eastern United States

Parts of the Eastern United States were also once plagued by some of the highest levels of acid rain in the world, due to emissions from Midwestern coal-burning power plants. In parts of New Jersey, for example, over 90 percent of freshwater streams are still acidic today due to acid rain, according to the U.S. Environmental Protection Agency. While the effects of acid rain are still felt in the region, acid rain itself has significantly decreased as a result of the Clean Air Act of 1970 and its subsequent amendments.

Changing Trends

Because of the laws enacted in the United States and Europe regulating emissions from coal-burning factories, and the adoption of mitigating technologies, such as limestone injection burners, reburners, flue gas desulphurizers and low-sulfur burners, these areas receive less acid rain today than in the past, according to a report from the environmental watchdog group Earthwatch Institute. The habitats in these countries suffered extensive damage and recovery is slow, but international concern over acid rain has since shifted focus to other parts of the world. In China and India, rapid industrial growth and lax pollution regulations could combine to produce the highest levels of acid rain in the developing world.

Acid Rain in Asia

Since the year 2000, levels of nitric and sulfuric acid in precipitation have been steadily increasing in Asian cities such as Beijing and New Delhi as domestic demand for electricity and manufactured goods increases. Without pollution regulations on the rapid industrial growth in the developing nations of China and India, acid rain could continue to grow in potency and reach until a similar crisis level as seen in Europe and the United States in the 1980s, according to a report by Science News.

Solutions and Ways Forward

In the United States, there are measures to protect the environment from the effects of acid rain including the EPA's Acid Rain program developed following the Clean Air Act Amendment of 1990 which aims to lower sulfur dioxide emissions from power plants. Responsible steps like these, towards lowering contaminants in the air can help to halt the destruction of acid rain.