Acid Rain Effect On Lakes and Aquatic Ecosystems

One of the direct effects of acid rain is on lakes and its aquatic ecosystems. There are several routes through which acidic chemicals can enter the lakes. Some chemical substances exist as dry particles in the air while others enter the lakes as wet particles such as rain, snow, sleet, hail, dew or fog. In addition, lakes can almost be thought of as the "sinks" of the earth, where rain that falls on land is drained through the sewage systems eventually make their way into the lakes. Acid rain that falls onto the earth washes off the nutrients out of the soil and carries toxic metals that have been released from the soil into the lakes. Another harmful way in which acids can enter the lakes is spring acid shock. When snow melts in spring rapidly due to a sudden temperature change, the acids and chemicals in the snow are released into the soils. The melted snow then runs off to streams and rivers, and gradually make their way into the lakes. The introduction of these acids and chemicals into the lakes causes a sudden drastic change in the pH of the lakes - hence the term "spring acid shock". The aquatic ecosystem has no time to adjust to the sudden change. In addition, springtime is an especially vulnerable time for many aquatic species since this is the time for reproduction for amphibians, fish and insects. Many of these species lay their eggs in the water to hatch. The sudden pH change is dangerous because the acids can cause serious deformities in their young or even annihilate the whole species since the young of many of such species spend a significant part of their life cycle in the water.

Subsequently, sulphuric acid in water can affect the fish in the lakes in two ways: directly and indirectly. Sulphuric acid (H₂SO₄) directly interferes with the fish's ability to take in oxygen, salt and nutrients needed to stay alive. For freshwater fish, maintaining osmoregulation is key in their survival. Osmoregulation is the process of maintaining the delicate balance of salts and minerals in their tissues. Acid molecules in the water cause mucus to form in their gills and this prevents the fish to absorb oxygen as well. If the buildup of mucus increases, the fish would suffocate. In addition, a low pH will throw off the balance of salts in the fish tissue. Salts levels such as the calcium (Ca⁺²) levels of some fish cannot be maintained due to pH change. This results in poor reproduction - their eggs produced would be damaged; they are either too brittle or too weak. Decreased Ca⁺² levels also result in weak spines and deformities. 

For example, crayfish need Ca⁺² to maintain a healthy exoskeleton; low Ca⁺² levels would mean a weak exoskeleton. Another type of salt N⁺ also influences the well-being of the fish. As nitrogen-containing fertilizers are washed off into the lakes, the nitrogen stimulates the growth of algae, which logically would mean an increase in oxygen production, thus benefitting the fish. However, because of increased deaths in the fish population due to acid rain, the decomposition process uses up a lot of the oxygen, which leaves less for the surviving fish to take in.

Indirectly, sulphuric acid releases heavy metals present in soils to be dissociated and released. For example, aluminium (Al⁺²) is harmless as part of a compound, but because acid rain causes Al⁺² to be released into the soils and gradually into the lakes, it becomes lethal to the health of the fish in the lakes. Al⁺² burns the gills of the fish and accumulates in their organs, causing much damage. So, although many fish may be able to tolerate a pH of approximately 5.9, this acid level is high enough to release Al⁺² from the soils to kill the fish. This effect is further augmented by spring acid shock. The effect of acid rain can be dynamically illustrated in a study done on Lake 223 which started in 1976. Scientists monitored the pH and aquatic ecosystem of Lake 223. They observed that as the pH of the lake decrease over the years, a number of crustaceans died out because of problems in reproduction due to the acidity of the lake caused by acid precipitation. At a pH of 5.6, algae growth in the lake was hindered and some types of small died out. Eventually, it was followed by larger fish dying out with the same problem in reproduciton; there were more adult fish in the lake than there were young fish. Finally, in 1983, the lake reached a pH of 5 and the surviving fish in the lake were thin and deformed and unable to reproduce. This case study obviously illustrates the significant effect of acid rain on lakes and its aquatic ecosystem.

The following is a chart which summarizes the effect of the pH level of the lake on its lifeforms.

pH LEVEL	EFFECTS
<6 font="">	*Basic forms of food die off. Eg. Mayflies and stoneflies are important food sources for fish. They can't survive at this pH level.
<5 .5="" font="">	*Fish cannot reproduce. *Young have difficulty staying alive. *More deformed adult fish due to lack of nutrients. *Fish die of suffocation.
<5 .0="" font="">	*Fish population die off.
<4 .0="" font="">	*Very different lifeforms, if any, from before.

The "safe" level of mercury in food has been set at about 0.05 parts per million. Indians and Eskimos in parts of Canada and the United States eat fish and seal meat with mercury levels as high as 15.7 and even 32.7 parts per million.

Fish, being one of the primary members of the food chain, is food for many other lifefoms, including hunans. Because toxic materials such as mercury are deposited in the fish due to acid rain, it is dangerous for humans to consume the fish. Like the domino effect, fewer fish can be sold as food, fishermen lose their hobby and people selling fishing supplies are affected. Amphibians are also affected; like the fish, they cannot reproduce in an acidic environment. The amphibian embyos have membranes that are too tough because of the acids, such that they are unable to break through at the proper time. So, they continue to grow, only to have deformed spines. They are then killed by a fungus that has been allowed to grow on their membranes. Hence, in essence, the effects of acid rain on lakes and its aquatic ecosystem are numerous and overwhelmingly magnified as we move down the food web.

In just ten years, from 1961 to 1971, Lumsden Lake in the beautiful Killarney region of Ontario, Canada, went to a pH reading of 6.8 to 4.4. That's an increase in acidity of more than 200 times. Most lakes with dropping pH values are at higher elevations. These lakes are usually small and located in watersheds where the rock and soil have a low neutralizing capacity.

Acid Rain

1. Washes minerals as calcium out of the soil and with the lack of these minerals, the trees and other plants are hurt. Impacts crop growth and soil structure. For optimum growth, many plants have a specific pH level and acid rain varies that number affecting the growth. Can also change the ionic balance in clayey soils, affecting structure.

2. At higher altitudes, trees are weakened by the acid in clouds and the mountaintops turn barren. A forest damaged by acid rain contains fewer niches for wildlife.

3. Acid is added to rivers and lakes, which in turn affects plants and fish in the water. Acidic water reduces the pH of water and impacts the health and breeding success of fish and aquatic invertebrates. Increases the metal amount in the water. 

4. Stone and metal is eaten away by acid so it is weathered more quickly than naturally.

5. Sulfur dioxide and nitrogen oxides (pollutants causing acid rain) are inhaled and causes an increase in heart, lung conditions, and premature death.

How is Acid Rain produced?

Acid rain is produced by a chemical reaction created when sulfur dioxide and nitrogen oxides are released into the air. When mixed with water, oxygen, and other chemicals from rising high into the atmosphere - Acid rain is formed. Sulfur dioxide and nitrogen oxides can be carried far by the wind and dissolved easily in water. As a result of being carried the compounds become rain, sleet, snow, and fog. The main reason these compounds are created is by humans. Electrical utility plants send out the majority of sulfur dioxide and much of the nitrogen oxides when fossil fuels (coal) are burned to produce electricity. Approximately 15 million tons of sulfur dioxide is pumped out each year, out of the 22 million tons in total generated annually by other human activities. Nitrogen oxides account for almost 30% of all acid deposition. Industrial processes, cars, trucks, and buses are also release a large number of nitrogen oxides and sulfur dioxide into the air. As nitric acid and sulfuric acid eventually fall back to Earth's surface as acid deposition  it falls as wet precipitation (rain, snow, or fog) or dry precipitation (gases or acidic salts).

When was Acid Rain first noticed?

Acid rain began entering the atmosphere during the Industrial Revolution and was first discovered by Robert Angus Smith (a Scottish chemist) in 1852. The relationship between acid rain and atmospheric pollution was discovered in that year in Manchester, England. Although discovered in the 1800s, acid deposition didn't gain public notice until the 1960s and it was coined "acid rain" in 1972. Harold Harvey was among the first that researched a "dead" lake. The public was noticing more and more in the 1970s when reports about problems in the Hubbard Brook Experimental Forest in New Hampshire was published in the New York Times. 

Where is Acid Rain most common?

Acid deposition is present in the northeastern United States, southeastern Canada, and much of Europe including areas of Sweden, Norway, and Germany, today. Portions of South Asia, South Africa, Sri Lanka, and southern India are in huge danger of becoming impacted by acid rain in the future. Acidification is occurring in the Adirondacks and Catskill Mountains in New York State, the Appalachians, the upper Midwest, eastern Canada, Scandinavia, parts of the United Kingdom, and mountainous areas in the western U.S.Today, acid deposition is present in the northeastern United States, southeastern Canada, and much of Europe including portions of Sweden, Norway, and Germany. In addition, parts of South Asia, South Africa, Sri Lanka, and Southern India are all in danger of being impacted by acid deposition in the future. The most acidic lake in the U.S. is Little Echo Pond in Franklin, New York, with a pH of 4.2. Over 90% of streams are acidic in the New Jersey Pine Barrens. 30% of streams and 70% of lakes are at risk in the mid-Appalachian region (severe enough to kill fish).

Does the world view Acid Rain as a major concern?

The world through EPA's eyes is a serious concern. EPA is doing everything they can to make sure everyone knows of the problems being dealt with because of acid rain. The problem with most of the world is that they're ignorant to the problem surrounding them. The world is not educated on the difficulties going on in the world around them, nor that we're trying to keep this problem from spreading to Australia. If more of the world knew about acid rain and how serious it actually is, many more would be doing their part in order to help out in solving this ever-spreading problem. Acid rain is dangerous, and needs to be viewed as a major concern, whether of not it actually is. 

What has the world done (if anything) to counteract the effects or production of Acid Rain?

1. Acid Rain Programs from congress:

Congress passed a law (the Clean Air Act Amendments of 1990) that stated that EPA should begin the Acid Rain Program. This program put limits on the amount of sulfur dioxide that power plants are allowed to release into the air and gave allowances to the power plants in order to cover their sulfur dioxide emissions. This also reduces the amount of nitrogen oxides allowed to be released from power plants. 

2. Reducing pollution:

Many different ways have been found by scientists in order to reduce the amount of sulfur dioxide being released from coal-burning power plants. One of the ways was to use coal that contains less sulfur. A second way was to "wash" the coal in order to remove amounts of the sulfur. Another  way was to install scrubbers which removes the sulfur dioxide from gases leaving the smokestack. And last, power plants are beginning to change the way they burn coal because nitrogen oxides are  created through the process of burning coal and other fossil fuels.

3. Using other sources of energy:

In order to reduce acid rain, renewable energy sources (solar and wind power), and items such as nuclear power, hydro-power  and geothermal energy can be used without burning fossil fuels. These renewable energy sources help to reduce acid rain by producing much less pollution. These sources can be used to power machinery and to produce electricity. Nuclear and hydro-power are used most widely in the U.S., as wind, solar, and geothermal energy have not been tested on a big enough scale to make them economically-feasible alternatives to fossil fuels. Natural gas, batteries, and fuel cells are also available to power automobiles as an alternative energy. 

4. Cleaner cars:

Being as cars and trucks are major sources of the pollutants that produce acid rain, something needed to be changed here. One car alone does not produce much pollution, but all the cars added together out on the road create tons. So, car manufacturers are required to reduce the amount of nitrogen oxides and other pollutants released from new cars. One new item of technology created is the catalytic converter which has been used for over 20 years to reduce nitrogen oxides released from cars. Cars are also beginning to use a cleaner fuel, such as natural gas. Cars labeled as low emissions vehicles are cars that produce less pollution and are better for the environment. There is a guide called EPA's Green Vehicle Guide used to determine which cars are low emissions vehicles. Tailpipe restrictions were tightened recently in order to help lower nitrogen oxides emissions. 

5. Restoring the environment:

Because of the deepening penetration into the fabric of the ecosystem caused by acid rain the chemistry of the soil, streams, and narrowing have been hugely changed. Since there have been so many changes it can sometimes take many years for these ecosystems to recover, even after the emissions have been reduced and the pH balance is restored to normal. It can take decades, or even centuries for acidified lakes, streams, forests, and soils to heal. But, in order to make this process faster limestone or lime can be added to acidic lakes to "cancel out" the acidity. The process (liming) has been majorly used in Norway and Sweden but not very often in the U.S. This process tends to be expensive and has to be a reoccurring thing in order to keep it to returning to the previous condition. It is only considered a short-term remedy in specific areas, rather than an effort to reduce/prevent pollution. The broader problems of changes in soil chemistry and forest health is not solved and it does nothing to help with visibility reductions, materials damage, and risk to human health. But liming can help to keep fish in a lake, allowing the population of fish around to survive in that area until the emissions are reduced in their area.

6. As individuals:

Acid deposition is caused by the cumulative actions of millions of individual people, therefore each individual can reduce their contribution to the problem. One can:

Turn off lights, computers, and other appliances when not being used.

Use energy-efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc.

Only use electric appliances when needed.

Keep thermostat at 68 degrees in the winter and 72 degrees in the summer. When away from home lower the temperature in the winter and raise the temperature in the summer.

Insulate home

Carpool, use public transportation, walk, or bicycle.

Buy low emission vehicles and keep it maintained.

Be well informed.