Transcript Chapter 32
Essentials of Biology Sylvia S. Mader Chapter 32 Lecture Outline Prepared by: Dr. Stephen Ebbs Southern Illinois University Carbondale Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 32.1 Resources and Pollution • Resources are the materials that meet the basic needs of living organisms. – There is a finite supply of nonrenewable resources. – Renewable resources are continually produced and are not finite. • Pollution occurs when the release of by-products from resource utilization alter the environment in an undesirable way. Land • Humans require land for habitation, industry, and agriculture. • Human use of land has negative impacts. – Human activities contribute to the erosion and pollution of beaches. – The use of land located near deserts can lead to desertification. – Deforestation of land can also lead to desertification and a loss of biodiversity. Land (cont.) Land (cont.) Land (cont.) Water • Humans alter the distribution of water in the environment with dams and aquifers. • Dams have several negative impacts. – The natural course of rivers is disrupted, damaging estuaries. – Water is lost by evaporation and seepage. – Salt and agricultural runoff can affect the water. – Sediment can build up, reducing the effectiveness of the dam. Water (cont.) • Water redistribution and/or removal can have other consequences for the environment. – Subsidence can occur when groundwater is removed. – Groundwater removal can also cause saltwater intrusion. • Water conservation is becoming increasingly important as the availability of potable water supplies decreases. Food • Modern agricultural techniques have had several negative effects. • Monoculture has increased the susceptibility of crops to disease and insect herbivory. • Heavy use of fertilizers and pesticides has polluted the environment. Food (cont.) • Over-irrigation has depleted water supplies. • Energy consumption during agriculture has drawn from finite fossil fuel supplies. • Agriculture has contributed to soil loss. Food (cont.) • Other efforts to enhance the human food supply have had mixed results. • The Green Revolution and genetic engineering have produced high productivity plants that often require high inputs of water and nutrients. Food (cont.) • Livestock production has provided protein for the human diet but has also been energy intensive and a source of pollution. • Fishing has also provided protein but is depleting the populations of some fish. Energy • Nuclear power provides ~6% of the world’s energy. • Nuclear power can be dangerous and produces radioactive wastes that persist for thousands of years. • Most of the world’s energy (~75%) is provided by nonrenewable fossil fuels. • The burning of these fossil fuels introduces pollutants into the environment. Fossil Fuels and Global Climate Change • Carbon dioxide, a by-product of fossil fuel production, is a greenhouse gas that many believe is causing global climate change. – Temperatures are expected to rise. – The polar ice caps will melt. – The melting ice caps will cause sea levels to rise. Fossil Fuels and Global Climate Change (cont.) Renewable Energy Sources • There are five main forms of renewable energy. – Wind power – Hydropower (hydroelectric power) – The geothermal energy (heat from beneath the Earth’s surface) – Solar energy – Solar-hydrogen energy (extraction of hydrogen from water by electrolysis) Renewable Energy Sources (cont.) Minerals • Minerals are nonrenewable resources that are often mined from the environment. – Fossil fuels are considered minerals. – Nonmetallic minerals include phosphate, sand, and gravel. – Examples of metallic minerals include aluminum, copper, iron, nickel, and precious metals. Other Sources of Pollution • Heavy metals are a threat to human health and ecosystem health. • Synthetic organic compounds can be toxic and can influence global climate change. • These toxic compounds can accumulate in food chains through biological magnification. Other Sources of Pollution (cont.) Other Sources of Pollution • Industrial wastes pollute the environment by releasing potentially hazardous compounds. • Release of raw sewage can contribute to human disease and pollute water sources. 32.2 Biodiversity • Biodiversity can be described as the variety of life on the Earth. • Currently, biodiversity is decreasing due to rapid extinction of species. • Extinction is caused by a variety of factors. • Conservation biology is an effort to protect biodiversity. 32.2 Biodiversity (cont.) Direct Values of Biodiversity • Biodiversity can provide value directly to humans. – Medicinal value through pharmaceuticals and natural compounds – Agricultural value as a food source – Consumptive use value for commercial products Indirect Values of Biodiversity • Biodiversity can provide indirect value. – Contribution to the biogeochemical cycling of nutrients in the environment – Disposal of wastes (decomposition) – Natural filtration and regeneration of water sources – Reduction of erosion – Regulation of climate – Ecotourism Indirect Values of Biodiversity (cont.) Working Toward a Sustainable Society • A sustainable society can provide the needed resources and protect biodiversity. • Current human society is not sustainable. – More land is used for human purposes, rather than left as natural ecosystems. – Agriculture relies on nonrenewable resources. – Too much agriculture is devoted to livestock. – There is too much reliance on nonrenewable fossil fuels and minerals. Working Toward a Sustainable Society (cont.) Working Toward a Sustainable Society (cont.) • A sustainable society would have the following characteristics. – Renewable energy sources would be used to provide energy. – Heat and waste materials would be used efficiently. – There would be maximal recycling of all resources. Working Toward a Sustainable Society (cont.)