2.2 – Assessing the Impact of Human Activities on Ecosystems

1. 2.2 – Assessing the Impact of Human Activities on Ecosystems Pollution, Soil and Water

2. Pollution Pollution is any substance added to the environment that produces a condition that is harmful to organisms.

3. Great Pacific Garbage Patch The Pacific gyre covers a large area of the Pacific Ocean in which the water circulates clockwise in a slow spiral. The currents tend to force any floating material into the central area of the gyre. There are few islands on which the floating material can beach. So it stays there in the gyre, in astounding quantities (millions of tonnes of garbage). The equivalent of an area the size of Texas swirling slowly around like a clock.

4. Great Pacific Garbage Patch

6. Pollution Not all pollution is as easy to see as the pollution that litters the North Pacific Ocean. Other forms of pollution affect our ecosystems daily, and are not obvious, though their effects may be.

7. Acid Rain Acid Rain is rain that has a high acidity due to the dissolving of nitrogen and sulfur containing chemicals in the rain.

8. Acid Rain Most of these nitrogen and sulfur containing compounds come from emissions released into the air as a result of such activities as mining and refining, electric power generation (coal burning power plants), and from burning fossil fuels, especially in automobiles.

9. Acid Rain Formation and Deposition

10. Acid Rain Acid rain affects soils, plants, waterways, and terrestrial and aquatic animals.

11. Assessing Soils Soil is a loose covering on the ground, which contains a mix of organic matter (living and decomposing), minerals and moisture. Soil contains a number of living organisms including plants, insects, small rodents, worms, fungi and bacteria.

12. Assessing Soils To assess the quality of soil, three properties are taken into account: • Soil profile (the layer and make up of the soil) • Soil type (the type and quantity of particles in the soil) • Acidity (connected to the chemical environment)

13. Soil Profile Soil is made of three layers: • Topsoil – upper layer of soil, composed mainly of humus (decaying organic matter). This is where most organisms live in the soil. • Subsoil – layer below topsoil. It contains little to no organic material (except bacteria and roots of large trees) • Bedrock– bottom layer of solid rock. Water that percolates through the soil often is trapped above the bedrock (known as the water table).

14. Soil Profile

15. Soil Types • Loam– this is the most fertile soil. It contains rocky particles of many different sizes. It has many air spaces that allow air and water to pass through. It is loose, so plants can easily establish roots. It is rich in humus (organic matter) which provides nutrients.

16. Soil Types • Clay–this soil contains small particles that pack together tightly, leaving small air spaces. Roots have difficulty spreading in clay, and water does not drain well.

17. Soil Types c) Sandy soil – particles are large compared to clay. These are large air spaces between particles, allowing water to drain quickly, and permitting root growth.

18. Human Impacts on Soil Soil Erosion This is the loss of soil when it is removed by wind or moving water. Erosion is minimized when the roots of plants keep topsoil in place.

19. Human Impacts on Soil (Negative) Ploughing fields turns topsoil, removing roots of plants, and exposing soil to wind and air. Overgrazing can also remove the plants that prevent erosion. When topsoil is lost from soil, organic matter (nutrients) are lost, and the soil can no longer be used for growing crops.

20. Human Impacts on Soil (Positive) Crop rotation This is the practice of growing different types of crop on a particular area of land each year. When plants grow in soil, they take in nutrients from the soil. These nutrients become depleted if the same crop is grown year after year.

21. Human Impacts on Soil If nutrients are depleted, farmers often turn to fertilizers to replenish needed nutrients. Plants of the legume family (soybeans, peas, alfalfa) help return some needed nitrogen based nutrients to soil.

22. Try these questions: Page 85 Questions 1, 3, 8, 10, 13, 14, 16.