Trees, acid rain damage

Figure 7.2 Acid rain occurs when water comes into contact with sulfur and nitrogen oxides in the atmosphere, which can come from natural sources or from man-made sources like cars or power plants. These acid rain-damaged coniferous trees live in the Karkonosze National Park in Silesia, Poland.

Acid-rain damage to buildings, statues, and trees amounts to billions of dollars a year. 

We ve all heard about the ravages of acid rain. Resulting from toxic emissions in the environment, acid rain damages the leaves and needles on trees, reduces a tree s ability to withstand cold, drought, disease, and pests, and even inhibits or prevents plant reproduction. In an effort to stay alive and combat the acidity, tree roots pull important nutrients such as calcium and magnesium from the soil. These alkaline nutrients balance the effects of acid rain, but as they become depleted from the soil, the trees ability to survive is further strained. 

When acid rain falls or flows into lakes and streams, it makes them more acidic. Some species of aquatic animals— such as trout, bass, snails, salamanders, and dams—cannot tolerate the increased acidity and die. This then disturbs the ecosystem of the lake, resulting in imbalances that may lead to the death of other aquatic species. Acid rain also weakens trees by dissolving nutrients in the soil and by damaging their leaves. Appalachian red spruce trees have been the hardest hit, with many forests showing significant acid rain damage. 

Acid rain damages structures made out of metal, marble, cement, and limestone, as weU as harming and jxjssibly killing aquatic life and trees. 

Sulphur dioxide forms because petrol contains a little sulphur. It attacks the lungs and breathing tubes, causing bronchitis and other diseases. It also dissolves in rain, making it acidic. The acid rain damages trees, plants, buildings, and metalwork. 

Acid rain adversely affects trees as well (Figure A). It appears that the damage is largely due to the leaching of metal cations from the soil. In particular, H+ ions in acid rain can react with insoluble aluminum compounds in the soil, bringing Al3+ ions into solution. The following reaction is typical ... 

Trees damaged by acid rain in the Great Smoky Mountains. 

Prolonged exposure to acid rain causes forest soils to lose valuable nutrients. It also increases the concentration of aluminum in the soil, which interferes with the uptake of nutrients by the trees. Lack of nutrients causes trees to grow more slowly or to stop growing altogether. More visible damage, such as defoliation, may show up later. Trees exposed to acid rain may also have more difficulty withstanding other stresses, such as drought, disease, insect pests and cold weather. 

Acid rain is one of the worst manifestations of the damage we, as humans, inflict on our planet. Chemicals combine with elemental oxygen during the burning of fossil fuels, trees and rubbish to generate large amounts of acidic oxides such as nitrogen monoxide (NO), carbon dioxide (CO2) and sulphur dioxide (SO2). 

Acid deposition or, acid rain, occurs when SO2 and oxides of nitrogen (NOx) react with water, oxygen, and oxidants to form acidic compounds. It is deposited in dry form (gas, particles) or wet form (rain, snow, fog), and can be carried by wind hundreds of miles across state and national borders. Acid rain harms lakes and streams, damages trees, crops, historic buildings, and monuments. 

The effects of acid rain can be seen in lakes and streams, in forests, and on all kinds of structures. The lowered pH kills fish eggs, fish, and many other organisms that live in lakes and streams. In forests, the acid can kill the leaves and needles of trees. It damages the soil by depleting it of nutrients, which stunts plant growth. Acid rain also eats away at the surfaces of buildings and other structures. Structures made of marble and other calcium-containing stone are particularly sensitive to acid rain. 

A marble statue is being slowly dissolved by reaction of calcium carbonate with acid rain (top). A researcher examines tree branches damaged by acid rain on Mount Mitchell in North Carolina (bottom). 

Sulfur dioxide. The sources are burning coal and oil, especially high sulfur coal from Eastern US, and industrial processes (paper and metal industry). Health effects include breathing problems, which may cause permanent damage to lungs. Environmental effects are as follows S02 is an ingredient of acid rain (acid aerosols), which can damage trees and life in lakes. Acid aerosols can also reduce visibility. 

Acid rain increases the acidity of some types of soil, resulting in the removal of essential nutrients from the soil. The loss of nutrients adversely affects the area s vegetation, leaving trees and other plants with less resistance to disease, insects, and bad weather. Acid rain also increases the acidity of streams, rivers, and lakes, which can kill or harm aquatic life. As Figure 26-8 shows, damage to trees and to outdoor surfaces can be extensive. The acid in precipitation reacts with CaC03, the major component of marble and limestone. What products are produced by this reaction ... 

There is little published work on the relationship between acid rain and insects. However, Smith et al. (37) point out that a number of damaging forest insects detect and respond to trees under stress. Environmental changes such as acid rain could cause tree stress. The insects that would bear observation would be those that spend all or part of their life cycles on leaves or needles, as that is where injury occurs and substances are leached, or microarthropods inhabit leaf litter and soil. 

Damage to metal, concrete, trees and crops has been reported in areas seriously affected by acid rain (Zhao and Sun, 1986 Zhao and Xiong, 1988). 

The additional burden of human air pollution, however, has made acid rain an important environmental concern. Acid rain may acidify lakes and streams, making the water unsuitable for some fish and other wildlife. Eur-ther damage has been reported in soil and tree vegetation, which are sensitive to the acid level of rainwater. 

In addition to its health effects on humans, sulfur dioxide has some important consequences for the physical and biological environment. Those effects occur because sulfur dioxide released to the atmosphere from electricity-generating plants and factories combines with moisture in the air to form sulfuric acid. Sulfuric acid then falls to earth in the form of acid rain, acid snow, or some other form of acid precipitation where it damages buildings and other structures, trees and other plant life, and fish and other aquatic organisms. Since 1995, the EPA has sponsored a variety of control programs designed to reduce the release of sulfur dioxide into the atmosphere to prevent such problems. 

Similar to smog, acid rain is caused by chemical reactions of pollutants like sulfur dioxide and nitrogen oxides with oxygen and water in the air. The acidic pollutants formed in these reactions are the cause of acid rain. In addition to environmental pollution due to human activi- Trees and other plants are seen here, damaged or. . 1 1 killed by acid rain. Acid rain results when water in... 

Acid rain dams es trees in several ways. It disturbs the stomata (openings) in tree leaves and causes increased transpiration and a water deficit in the tree. The surface structures of the bark and the leaves can also be destroyed by the acid. Acid rainfall can acidify the soil, damaging fine root hairs and thus diminishing nutrient and water uptake. In addition, acid rain dissolves minerals that are insoluble in groundwater and surface waters of normal pH, and many of these minerals contain metal ions toxic to plant life. For example, acid rain dissolves aluminum hydroxide in the soil, allowing aluminum ions (Al ) to be taken up by the roots of plants, where they have toxic effects. 

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