Human+Interference+SLS

Chapter 23 Human Interference (WIki) Last Unit...Life with us. Human Interference with the water cycle (p.499) 1. What are the three ways humans disrupt the natural water cycle? They withdraw water from aquifers, clear vegetation from land and build roads and buildings that prevent percolation and increase runoff and also interfere with the natural processes that purify water and instead add pollutants like sewage and chemicals to water. 2. What is groundwater mining and what is the danger of this process? Groundwater mining is withdrawals from aquifers that exceed any possibility of recharge. This could lead to residents that may run out of groundwater at least for irrigation purposes. 3. Why is it possible to run out of freshwater, a renewable resource? Freshwater only makes up about 3% of the world’s supply of water and new supplies are always being produced. It is possible to run out when the available supply runs off instead of entering bodies of freshwater and aquifers or has become so polluted that it is not usable. Human Interference with the carbon cycle (p.501) 1. How are humans increasing the amount of carbon dioxide being deposited in the atmosphere on top of "natural" sources? More carbon dioxide is being deposited in the atmosphere than is being removed. This increase is largely due to the burning of fossil fuels and the destruction of forests to make way for farmland and pasture. 2. What are the greenhouse gases and what are the human causes of these gases? Nitrous oxide from fertilizers and animal wastes and methane from bacterial decomposition, particularly in the guts of animals in sediments and in flooded rice paddies. 3. Why are these gases called greenhouse gases? Because just like the panes of a greenhouse, they allow solar radiation to pass through but hinder the escape of infrared rays back into space. 4. What are some possible dangers of global warming? If the Earth’s temperature rises, more water will evaporate, forming more clouds and setting up a positive feedback effect that could increase global warming. If so, glaciers will melt and sea levels will rise, not only due to this melting but also because water expands as it warms. Water evaporation will increase and most likely there will be increased rainfall along the coasts and dryer conditions inland. Human Interference with the Ozone Shield (p.506) 1. What are the ozone shield and what chemical reaction produces ozone? A layer of ozone that absorbs most of the ultraviolet rays of the sun so that fewer rays strike the Earth. Ozone forms when ultraviolet radiation form the sun splits oxygen molecules and then the oxygen atoms combine with other oxygen molecules to produce ozone (O3). 2. What are ozone holes? Severe depletions of the ozone layer. 3. Why are ozone holes dangerous to humans? The holes cause for a rise in cataracts and nonmelanoma skin cancers for every 10% drop in the ozone level. 4. What human pollution destroys ozone molecules? Chlorine atoms. 5. What are common sources of chlorine pollution? CFC is Freon, a coolant found in refrigerators and air conditioners. These are also used as cleaning agents and foaming agents during the production of Styrofoam. Human Interference and the Arctic (p. 507) 1. What does ANWR stand for and what is it? Arctic National Wildlife Refuge is a home for a variety of wildlife and also contains substantial oil reserves. 2. Why is ANWR the source of political debate? This is up for debate due to the designation of off-limits of oil drilling without congressional authorization. 3. What are the benefits of drilling for oil in ANWR? By using the newest drilling methods removing the oil and disposing of wastes would cause much less disruption to the surface environment compared with techniques used in the past. Alaskans would benefit by the creation of new jobs and a boost to the state economy. 4. What are the risks of drilling for oil in ANWR? A reduced need for energy by making better use of existing resources.