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Lecture Presentation Chapter 16 Protecting Water and Air Resources Bradley Sieve Northern Kentucky University Highland Heights, KY © 2014 Pearson Education, Inc. 16.1 Water on the Move • Hydrological Cycle – Constant moving and changing of phases of water – Water table is the top of the saturation level in soil © 2014 Pearson Education, Inc. 16.1 Water on the Move • Lakes and streams are regions where the water table lies above the land surface • Aquifers are underground water reservoirs © 2014 Pearson Education, Inc. 16.1 Water on the Move • As water is removed from the soil, ground surface is lowered or subsides © 2014 Pearson Education, Inc. Concept Check An aquifer is a body of underground fresh water. Where does this water come from? © 2014 Pearson Education, Inc. Concept Check The source of all natural underground (and aboveground) fresh water is the atmosphere, which gets most of its moisture from the evaporation of ocean water. © 2014 Pearson Education, Inc. 16.2 Collectively, We Consume Huge Amounts of Water • Huge amounts of water are consumed each day – USGS data state that 6790 billion liters/day enter aquifers – We remove 1319 billion liters/day, about 20% – In dryer regions, our use outpaces the daily intake of water – Per person, that is 4380 liters/day in the United States © 2014 Pearson Education, Inc. 16.2 Collectively, We Consume Huge Amounts of Water © 2014 Pearson Education, Inc. 16.2 Collectively, We Consume Huge Amounts of Water © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water • Water pollution can be one of two types – Point source—one specific, well-defined location where pollution enters the water – Nonpoint source—pollutants originate at diverse locations © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water • Cleaning of Polluted Water – Pollutants in rivers and lakes can be cleaned because pollution is localized – Groundwater pollution is more difficult to clean • Groundwater is inaccessible • Slow flow rate on water in the aquifers © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water • Sources of Groundwater Pollution – Solid-waste disposal sites • Leachate—mixture of rainwater and chemicals from the solid waste – Sewage © 2014 Pearson Education, Inc. Concept Check What is the difference between a point source and a nonpoint source of pollution? © 2014 Pearson Education, Inc. Concept Check A point source arises from a specific location—you can pinpoint it on a map. A nonpoint source represents a collection of many sources, each difficult to trace. To specify a nonpoint source on a map, you need to draw a circle. © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water • Organisms exist in natural water sources – Aerobic bacteria • Bacteria that decompose organic matter in the presence of oxygen • Utilize oxygen in water, forming CO2, H2O, NO3–, and SO42– • Products are odorless and cause little harm © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water • Organisms exist in natural water sources – Anaerobic bacteria • Bacteria that decompose organic matter in the absence of oxygen • Produce dangerous and unpleasant products when decomposing materials • Products include methane (CH4), amines (such as NH2C4H8NH2), and sulfur compounds (such as H2S) © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water • Biochemical Oxygen Demand (BOD) – Amount of dissolved oxygen needed for aerobic bacteria to decompose organic matter – If amount of dissolved oxygen is lower than BOD • Organisms start to die off • Anaerobic bacteria begin to take over breakdown of organic materials © 2014 Pearson Education, Inc. 16.3 Human Activities Can Pollute Water • Algae Bloom – Rapid growth of algae and aquatic plants – The plants consume more oxygen than they produce, depleting overall oxygen level – Covers the surface of the water, reducing oxygen absorption from the air © 2014 Pearson Education, Inc. 16.4 Wastewater Treatment • Wastewater must be treated before it is released into bodies of water – Completed at water treatment centers © 2014 Pearson Education, Inc. 16.4 Wastewater Treatment • Primary-Level Wastewater Treatment 1) Screening of solid waste 2) Primary treatment where suspended solids settle out as sludge 3) Disinfection with either chlorine gas or ozone • After primary-level treatment, waste often passes through secondary and tertiary levels of treatment © 2014 Pearson Education, Inc. 16.4 Wastewater Treatment © 2014 Pearson Education, Inc. Concept Check Distinguish among the main functions of primary, secondary, and tertiary wastewater treatment. © 2014 Pearson Education, Inc. Concept Check Primary wastewater treatment removes the bulk of solid waste and sludge from the sewage effluent using screening devices and large settling basins. Secondary treatment provides oxygen to oxygendependent bacteria that serve to decompose organic matter. Tertiary treatment removes pathogens and wastes not removed by earlier treatments by filtering the effluent through beds of powdered carbon or other fine particles. © 2014 Pearson Education, Inc. 16.5 The Earth’s Atmosphere Is a Mixture of Gases • Air molecules interact with energy from the Sun and gravity to make our atmosphere © 2014 Pearson Education, Inc. 16.5 The Earth’s Atmosphere Is a Mixture of Gases • Atmosphere – Layer of air 50 km thick around the Earth – Provides oxygen, nitrogen, carbon dioxide, and other gases to living things – Protects from cosmic radiation and debris © 2014 Pearson Education, Inc. 16.5 The Earth’s Atmosphere Is a Mixture of Gases • Effects of Elevation – Atmospheric pressure • Pressure of air on objects submerged into the atmosphere • Pressure is higher at sea level than at elevated mountaintops – Temperature changes • Lower elevations are generally warmer due to the Earth’s surface radiating heat © 2014 Pearson Education, Inc. 16.5 The Earth’s Atmosphere Is a Mixture of Gases • Layers of the Atmosphere – Troposphere—lowest level of the atmosphere – Stratosphere—portion of the atmosphere above the troposphere © 2014 Pearson Education, Inc. 16.5 The Earth’s Atmosphere Is a Mixture of Gases • Troposhere – Lowest level of the atmosphere – Contains 90% of atmospheric mass – Contains essentially all of the water vapor and clouds – Where weather occurs – Extends up to about 16 km in height © 2014 Pearson Education, Inc. 16.5 The Earth’s Atmosphere Is a Mixture of Gases • Stratosphere – Reaches a height of 50 km – Contains the ozone layer at 20–30 km – Lower regions are cooler than the upper regions © 2014 Pearson Education, Inc. Concept Check What effect does the Earth’s gravity have on the atmosphere? © 2014 Pearson Education, Inc. Concept Check The Earth’s gravity pulls molecules in the atmosphere downward, preventing them from escaping into outer space. © 2014 Pearson Education, Inc. 16.6 Human Activities Have Increased Air Pollution • Air Pollutant – Material in the atmosphere that is harmful to health – Sources include natural and man-made sources – Clean Air Act restricts air pollutants © 2014 Pearson Education, Inc. 16.6 Human Activities Have Increased Air Pollution • Airborne Solid Particles – Ash, soot, metal oxides, and sea salts – Aerosols • Particles merged with water droplets, which facilitate reactions • Suspended in air for extended durations – Particulates • Larger particles that settle to the ground © 2014 Pearson Education, Inc. 16.6 Human Activities Have Increased Air Pollution © 2014 Pearson Education, Inc. 16.6 Human Activities Have Increased Air Pollution • Smog – A poisonous mixture of smoke, fog, and air – Occurs when a temperature inversion occurs © 2014 Pearson Education, Inc. Concept Check Why are temperature inversions more common during the day than at night? © 2014 Pearson Education, Inc. Concept Check A temperature inversion occurs when a body of warm air sits above a body of denser cold air. The higher air is warmed by the heat of the Sun, which is out only during the day. © 2014 Pearson Education, Inc. 16.6 Human Activities Have Increased Air Pollution • Two Types of Smog – Industrial • Smog that is high in particulates • Main component is sulfur dioxide – Photochemical smog • Contains particulates that participate in sunlight-induced chemical reaction • Contains chemicals such as NO2, HNO3, and ozone © 2014 Pearson Education, Inc. 16.6 Human Activities Have Increased Air Pollution • Hydrocarbons are another class of components in photochemical smog – Transformed to aldehydes and ketones, adding a foul odor – Often released when gas tanks are filled © 2014 Pearson Education, Inc. Concept Check How does the Sun help disperse air pollutants? © 2014 Pearson Education, Inc. Concept Check Sunlight warms the ground, which in turn warms the air, which then rises, carrying with it many air pollutants. © 2014 Pearson Education, Inc. 16.7 Carbon Dioxide Helps Keep the Earth Warm • Glass is transparent to visible light but not to infrared light – Leads to the greenhouse effect and warming of the interior © 2014 Pearson Education, Inc. 16.7 Carbon Dioxide Helps Keep the Earth Warm • Greenhouse Gases – Include carbon dioxide, water vapor, and other gases – Work in the same manner as glass to enclose and trap heat © 2014 Pearson Education, Inc. Concept Check What does it mean to say that the greenhouse effect is like a one-way valve? © 2014 Pearson Education, Inc. Concept Check Both the Earth’s atmosphere and glass allow incoming visible waves, but not outgoing infrared waves, to pass. As a result, radiant energy is trapped. © 2014 Pearson Education, Inc. 16.7 Carbon Dioxide Helps Keep the Earth Warm • Carbon Dioxide – Has a well-documented history as a greenhouse gas – Core samples show a close relationship between CO2 and global temperatures © 2014 Pearson Education, Inc. 16.7 Carbon Dioxide Helps Keep the Earth Warm • Carbon dioxide levels have increased since the Industrial Revolution – Increased CO2 levels correspond to increased average temperatures – CO2 is currently the number-one gas emitted by human activities – 158 billion tons have been added since 1958 © 2014 Pearson Education, Inc. 16.7 Carbon Dioxide Helps Keep the Earth Warm © 2014 Pearson Education, Inc. 16.7 Carbon Dioxide Helps Keep the Earth Warm • Modern Sources of CO2 – Burning of fossil fuels releases CO2 as the energy is released – Deforestation • Removes the CO2 sink of the growing vegetation • Releases additional CO2 if the material is burned © 2014 Pearson Education, Inc. 16.7 Carbon Dioxide Helps Keep the Earth Warm • Potential effects of global climate change are uncertain – Consensus is that increasing greenhouse gases will result in global warming – Many questions still remain due to the large number of variables © 2014 Pearson Education, Inc. Concept Check Why are scientists uncertain about the potential effects of global warming? © 2014 Pearson Education, Inc. Concept Check The uncertainty is due to the large number of variables that determines global weather patterns. As the debates continue, bear in mind that the issue is not global warming itself, but rather its potential effects. © 2014 Pearson Education, Inc.