2 The way we use landPeople use land in many ways. Three uses that change the land are agriculture, development, and mining.
3 Actions that affect land Development reduces the amount of farmland and destroys wildlifeOnce mined, land is often difficult to use for other purposes.Soil is one of Earth’s most valuable resources because everything that lives on land depends directly or indirectly on soil.
4 Plants depend directly on soil to live and grow. Animals depend on plants for food. Fertile soil is valuable because there is a limited supply. Less than one eighth of the land on Earth has soils that are well suited for farming.Soil is a renewable resource that can be found wherever weathering occurs. But it can take hundreds of years for just a few centimeters of soil to form.
5 DesertificationThe advance of desert like conditions in previously fertile areas, is important cause of soil loss. Wind erosion was the cause of soil loss on the Great Plains in the 1930s.The Great Plains cover an area from the prairies west to the base of the Rocky Mountains, including parts of North and South Dakota, Nebraska, Kansas, Oklahoma, and Texas. .
6 Fresh Water PollutionThe addition of any substance that has a negative effect on water or the living things that depend on the water is called water pollution.Water pollution can affect surface water, groundwater, and even rain.The substances that cause water pollution are called pollutants.
7 Types of pollutantsinclude disease-causing organisms, pesticides and fertilizers, industrial chemicals, metals, radioactive wastes, and petroleum products.The major sources of water pollution are human wastes, industrial wastes, agricultural chemicals, and runoff from roads
8 A point source is a specific source of pollution that can be identified, such as a leaking pipe. A nonpoint source is a widely spread source of pollution that can’t be tied to a specific point of origin, such as runoff from a highway.
9 Water pollution by factories and mines is a more common problem than sewage in most areas. Especially in the past, many factories released toxic chemicals directly into nearby waters.Agricultural chemicals that can enter surface water in runoff from fields include fertilizers and pesticides. The rich supply of nutrients in fertilizers encourages the growth of plants and algae in and around nearby bodies of water.
10 Air PollutionAir pollution is made up of gases, particles, or other substances in the air that are harmful to people or the environment.Harmful substances in the air, water, or soil are known as pollutants.
11 Pollutants in air may cause such health problems as headaches, eye irritation, coughs, allergies, and lung diseases.Most air pollution is the result of burning fossil fuels such as coal, oil, gasoline, and diesel fuel.
12 Cars and other motor vehicles cause almost half the air pollution from human activities. The burning of fossil fuels, including the burning of gasoline by cars and other vehicles, releases nitrogen oxides, hydrocarbons, and other pollutants into the air.
13 The nitrogen oxides, hydrocarbons, and other air pollutants then react with one another in the presence of sunlight to form a mix of ozone and other chemicals called photochemical smog.