Assessing the Impact of Human Activities (acidity, water. soil) on Ecosystems from text

Assessing the Impact of Human Activities (acidity, water. soil) on Ecosystems from text

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Assessing the Impact of Human Activities on Ecosystems Figure 2.20 The amount of plastic in the world’s oceans exceeds 100 million tonnes. Most of us usually encounter this plastic pollution only when it washes ashore as it has done here on Hawaii. Great Pacific Garbage Patch The world’s oceans are so big, it is easy to think that tossing garbage into them will not really affect the environment. Evidence suggests that the opposite is true. There are great circular ocean currents, called gyres, that swirl floating debris to their centres, and the debris stays there. The North Pacific Ocean has two large gyres, each thousands of kilometres across. People passing through them in sailboats have reported constant encounters with floating garbage. This does not mean, however, that there is an “island of floating junk” that you could bump into or photograph from space. It might be better for the environment if there actually were such an island. At least we could travel to it and clean it up. In reality, enormous amounts of garbage, mostly plastic, are spread out over thousands of square kilometres of ocean. These items float on or just beneath the surface. Occasionally, the North Pacific gyre brushes past the Hawaiian Islands and deposits mounds of plastic from across the world onto Hawaii’s beaches (Figure 2.20). Figure 2.21 This albatross chick died from plastic consumption . Acid Rain and Ontario’s Ecosystems Emissions from a variety of human activities contain pollutants that enter the atmosphere and can have wide-ranging effects on the environment. In Canada, emissions come from mining and refining metals, electrical power generation, oil and gas operations, and automobiles. Nitrogen- and sulfur-containing substances are two of the most common pollutants in emissions (Figure 2.22).
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Once these substances are released into the air, they combine with water vapour in the air and form acids. An acid is a common type of chemical. Some acids are safe for the environment. You even consume them in foods such as orange juice and salad dressing. However, many acids are not safe and can damage ecosystems. The acids formed in the air by emissions fall as acid rain . Acid rain affects soils, vegetation, lakes, rivers, and terrestrial and aquatic animals. Effects of Acid Rain Acid rain damages the waxy coating that protects leaves from infection. When acid rain seeps into soil, it burns the skin of earthworms. It increases the acidity of the soil and affects plant roots’ ability to absorb nutrients. Acid rain also makes bodies of water more acidic. Shellfish are the most sensitive because the acid in the water dissolves their shells. When lakes become acidic enough, no organisms can survive in them. These lakes have clear blue water but contain no life. When scientists discovered how acid rain was caused and its wide-ranging effects, governments put limits on
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This note was uploaded on 04/19/2011 for the course SCI 495 taught by Professor Staff during the Fall '08 term at Grand Valley State.

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Assessing the Impact of Human Activities (acidity, water. soil) on Ecosystems from text

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