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Chapter 4 Land and Soil Resources Section 1 Conserving Land and Soil 3 uses that change the land are agriculture, development, and mining. Less than 1/3 of Earth can be farmed. New farmland must be created for the growing populations. In the U.S. about a million hectares of farmland is developed each year. Development is the construction of buildings, roads, bridges, dams and other structures. Mining Mining is the removal of nonrenewable resources such as iron, copper, and coal from the land. Strip mining removes a strip of land to obtain minerals, and then replacing the strip. This exposes the soil and can be washed or blown away. These areas can remain barren for years before they are rich enough to support the growth of new plants. Protecting the Soil Poor soil management can result in 3 problems: erosion, nutrient depletion, and desertification. Terms Litter: The very top layer of dead leaves and grass. Topsoil: A mixture of rock fragments, nutrients, water, air, and decaying animal and plant matter. Subsoil: Below the topsoil, contains rock fragments, water and air, but less animal and plant matter. Bedrock: Soil that makes up Earth’s crust. It takes hundreds of years to form just a few centimeters of new soil. Erosion Is the process by which water, wind, or ice moves particles of rocks or soil. Nutrient Depletion Nutrient Depletion: When farmers plant the same crops in a field year after year. As a result, the plants use more nutrients than the decomposers can replace. The soil becomes less fertile. Desertification The advance of desertlike conditions into areas that previously were fertile. Restoring the Land Land Reclamation: The process of restoring an area of land to a more natural, productive state. Smooth and replace strip mines with new topsoil. Plant grass. Review List three ways that people use land. What are 3 problems that can occur when topsoil is not properly managed? Describe the effects of strip mining. Describe two methods for reducing soil erosion. Section 2 Solid Waste Every hour people throw away 2.5 million plastic bottles. Every year people throw away enough white paper to build a wall 4 meters high that stretches coast to coast. Every year people throw away 1.6 billion pens, 2.9 million tons of paper towels, and 220 million automobile tires. Problem of Waste Disposal Municipal solid waste : Waste materials produced in homes, businesses, schools, and other places in a community. Three methods of handling solid waste. You can bury it, burn it, or recycle waste. Leachate: Polluted liquid, from the rainwater that has dissolved chemicals from the waste. Sanitary Landfills: Holds municipal solid wastes, construction debris, and some types of agricultural and industrial waste. Incineration The burning of solid waste is called incineration. The advantages of incinerators is that they do not take up as much space as landfills, they do not pose the risk of polluting groundwater, and the heat they produce can generate electricity. Disadvantage is that they are more expensive to build. Recycling Recycling: The process of reclaiming raw materials and reusing them. Biodegradable: A substance that can be broken down and recycled by bacteria and other decomposers. Most recycling focuses on 4 major categories of products: metal, glass, paper, and plastic. Products to Recycle Metal Metals such as iron and aluminum can be melted and reused. Recycling metal saves money and causes less pollution than making new metal. Glass Glass is one of the easiest products to recycle because it can be melted down over and over to make new glass containers. Recycling glass is less expensive than making glass from raw materials. Less energy is required. It also reduces the environmental damage caused by mining for sand, soda, and limestone. Paper Most paper products can only be recycled a few times. Each time the paper is recycled to make pulp, the new paper is rougher, weaker, and darker. It takes about 17 trees to make one metric ton of paper. Plastics When oil is refined to make gasoline and other petroleum products, solid materials called resins are left over. These resins can be heated, stretched, and molded into plastic products. Numbers are found on the bottom of plastic containers. The numbers 1 & 2 are made from plastics that are often recycled. What Can You Do? These are sometimes called the 3 R’s – Reduce, Reuse and Recycle. Reduce: Refers to creating less waste in the first place. (Use cloth shopping bags than disposable paper or plastic bags. Reuse: Find another use for the object rather than discarding it.( Example ???) Recycle: Reclaiming raw materials to create new products. Composting Composting: Is the process of helping the natural decomposition processes break down many forms of waste. Compost is an excellent natural fertilizer for plants. Examples: (Raked leaves, grass, food waste, eggshells, coffee grounds and cow manure) Section 3 Hazardous Wastes Hazardous wastes are classified into 4 categories: Toxic, Explosive, Flammable, and Corrosive. Toxic Waste Are poisonous wastes that an damage the health of humans and other organisms. Explosive Waste Are waste that react very quickly when exposed to air or water, or that explode when they are dropped. Flammable Waste Are waste that catch fire easily and can begin burning at fairly low temperatures. Corrosive Waste Are waste that dissolve or eat through many materials. Radioactive Waste Are waste that contain unstable atoms. They require special disposal. Health Effects Short-term exposure to hazardous wastes, may cause irritation or more severe health problems. Long-term exposure to hazardous wastes, may cause diseases, such as cancer,, and may damage body organs, including the brain, liver, kidneys, and lungs. Disposal of Hazardous Waste Methods of hazardous waste disposal include burial in landfills, incineration, and breakdown by living organisms. Another method involves storing liquid wastes in deep rock layers. Scientists have not been able to develop completely safe methods for disposing of radioactive waste.
