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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum Copyright © 2008.

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Presentation on theme: "Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum Copyright © 2008."— Presentation transcript:

1 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ch 15 Freshwater Resources: Natural Systems, Human Impact, and Conservation Part 2: Environmental Issues and the Search for Solutions

2 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Journal questions… a) Make a list of all the things you use water for in a day or in your life. b) Do you think people on Earth use a lot of water? For what? c) How many gallons of water do you think you use in a day? d) Will useable water ever run out? Why? Let’s calculate an estimation of how much water we use.

3 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Freshwater systems Water may seem abundant, but drinkable water is rare Freshwater = relatively pure, with few dissolved salts -Only 2.5% of Earth’s water is fresh -Most freshwater is tied up in glaciers and ice caps

4 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Water, water everywhere but…

5 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The planet's renewable fresh water is finite— 10,000 cubic miles' worth is available each year on average—and constraints on its availability and use are increasingly evident.

6 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Water access… Nearly one billion people – about one in eight – lack access to clean water. More than twice that many, 2.5 billion people, don’t have access to a toilet. Lack of access to clean water and sanitation kills children at a rate equivalent of a jumbo jet crashing every four hours. Millions of women and children spend several hours each day collecting water from distant, often polluted sources. http://water.org/learn-about-the-water- crisis/billion/

7 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings More about water … http://www.amnh.org/exhibitions/water/media/water_inside _view.mov

8 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Water supplies houses, agriculture, and industry Proportions of these three types of use vary dramatically among nations -Arid countries use water for agriculture -Developed countries use water for industry

9 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Water is unequally distributed across Earth’s surface Different regions possess vastly different amounts of groundwater, surface water, and precipitation Many areas with high population density are water- poor and face serious water shortages

10 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Water is distributed unevenly in time, too Monsoon seasons bring concentrated storms -Half a region’s annual rain may fall in a few hours People erect dams to store water

11 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Areas where water use exceeds supply

12 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Where can we find access to freshwater? Surface water -Rivers, lakes, streams, wetlands, etc. Groundwater -Water found in underground rock formations (aquifers) Due to the nonstop motion of water on our planet, groundwater and surface water are connected!

13 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hydrolic Cycle (water cycle) Hydrolic cycle worksheet -http://www.ncwater.org/Education_and_Technical_As sistance/Project_WET/Downloads/Blank%20Hydrolog ic%20Cycle%20Worksheet.pdfhttp://www.ncwater.org/Education_and_Technical_As sistance/Project_WET/Downloads/Blank%20Hydrolog ic%20Cycle%20Worksheet.pdf Fill in the following words on your worksheet and let’s see what you remember. -EvaporationPrecipitation -TranspirationInfiltration -CondensationPercolation -Runoff

14 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Rivers and streams wind through landscapes Water from rain, snowmelt, or springs forms streams, creeks, or brooks. -Freshwater: The Journey video clip - http://dsc.discovery.com/videos/planet-earth-freshwater/ http://dsc.discovery.com/videos/planet-earth-freshwater/ These merge into rivers, and eventually reaches the ocean -Tributary = a smaller river slowing into a larger one -Watershed = the area of land drained by a river and its tributaries

15 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

16 Mississippi Watershed (river basin) When you turn on a faucet in New Orleans, some of the water that comes out has already been through many human bodies. WHAT!!!! Any ideas why?

17 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Here’s why New Orleans gets it’s drinking water from the Mississippi river, which extends 2,350 miles upstream. Over 70 upstream communities use the Mississippi for drinking, bathing, washing, agriculture and industry. -Much of the water that goes down a drain, ends up being treated at a water treatment plant and is released back into the river.

18 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Let’s see how a watershed works… You will need -one piece of scratch paper for your group -one aluminum tray -a blue marker, green marker and red marker.

19 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Watersheds Everywhere you go you are in a watershed. -Some are small and some are large. -No two watersheds are exactly alike. The boundaries and characteristics of a watershed depend on many factors including the geology of the region, climate and vegetation. -What kind of rock lies under the soil? Is the land steep or hilly? Does the soil have a lot of sand or gravel? -How much precipitation falls in one year? How strong are the winds? How warm and cold does it get? -Roots absorb water and anchor soil.

20 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Land use and watersheds Land use affects the quality (things in it) and quantity (how much) of water that drains from a watershed. -There are two ways to classify land use. -You can go into the field and measure the areas of land devoted to uses such as agriculture, housing or forests. -You can also work from inside using data gathered through remote sensing. -Remote sensing refers to collecting data from a distance. Not as reliable as field data but quicker. -Ex. Using aerial photos.

21 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Google Earth Let’s look at some aerial images from Google Earth and see what we can find out. Get your laptop…

22 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Let’s Review… How much freshwater is on our planet? -A) 2.5% B) 15% C) 40% D) 75% True or False: groundwater and surface water are connected in the water cycle. What do we call an area of land that drains into a river? What river does the water from Nebraska directly flow into?

23 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Streamflow Monitoring Watershed managers determine streamflow to assess water availabilty, to allocate limited water supplies among users and to manage flow problems. -Streamflow data is a measurement of the volume of water passing a given point over a period of time. (cubic feet per second) Streamflow data is used to create a hydrograph, which shows the amount of water flowing or discharged over a period of time.

24 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Patterns and forecasts Hydrologists use this streamflow data to predict streamflow during and after a rainfall, snowmenlt and drought. Watershed precipitation amounts or snowpack levels also help forecast streamflow levels. This information is then shared with water agencies, city planners, and farmers. Knowing historical patterns can help people manage a river and prepare for possible disasters.

25 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A river may shift course Floodplain = areas nearest to the river’s course that are flooded periodically -Frequent deposition of silt makes floodplain soils fertile Riparian = riverside areas that are productive and species-rich Water of rivers and streams hosts diverse ecological communities

26 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Now you make a hydrograph! You and a team will try to decide where you should build in a community. First you must create a hydrograph of the past 39 years in order to make a sound decision. -Project Wet pg. 295

27 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings So far… We’ve learned how to measure chemical indicators of water quality. -pH, dissolved oxygen (DO), conductivity (dissolved solids) We’ve also learned how to measure physical indicators of water quality. -turbidity, temperature, stream flow, surrounding vegitation Now we’re going to learn how to measure the water quality by using the animals in the stream as indicators.

28 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Looking at life in a water body… Some aquatic animals are very sensitive to changes in their surroundings. -If the water quality changes, they must move or they may die. One important type of stream animal is the benthic macroinvertebrate.

29 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A typical lake

30 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biological Indicators Biological indicator is the term we use when we look at living things in a water body to determine the water quality. They mainly include -Fish -Invertebrates -What is a benthic macro invertebrate? http://www.cacaponinstitute.org/Benthics/What%20is%20a%20Benthic%20Mac roinvertebrate%20-%20V.html http://www.cacaponinstitute.org/Benthics/What%20is%20a%20Benthic%20Mac roinvertebrate%20-%20V.html -Benthos in our waters http://www.epa.gov/bioindicators/html/benthosclean.html http://www.epa.gov/bioindicators/html/benthosclean.html -Plants -Amphibians

31 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Let’s play a game… -The class will be divided into 6 teams. Each team will need. -One deck of cards, one sorting sheet, and one map. -Each deck of cards represents live animals you brought back from a sampling site. -Lay the sorting sheet and map flat on a desk so everyone can see. -Read the information on the cards and practice saying the macro’s name. -Gather your cards and shuffle them together. -Find your site on the map. -Now sort your deck by matching the images on the cards to the images on the sorting sheet. Cont…

32 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Let’s see what happened… Which group has the most stacks of invertebrates? (Group 1, Group 2 or Group 3?) What kind of water quality does each group have? -Sketch and label the indicators that each group has. And identify the type of water (excellent, fair or poor) -Also identify what the land was used for at the site. (look at the map) -How did the land use affect the water quality? We are looking for BIODIVERSITY. It doesn’t matter how many macro’s you collected, what we need to know is how many types were present. The more biodiversity a water body has the healthier it should be.

33 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Lakes vary in their nutrients and oxygen Oligotrophic lakes and ponds = have low nutrient and high oxygen conditions Eutrophic lakes and ponds = have high nutrient and low oxygen conditions Eventually, water bodies fill completely in through the process of succession Inland seas = large lakes that hold so much water, their biota is adapted to open water

34 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Macro Matching game http://creekconnections.allegheny.edu/Modules/On- LineActivities/AquaticMacros/MacroinvertMatch/Macroi nvertebrateMatchGame.htmlhttp://creekconnections.allegheny.edu/Modules/On- LineActivities/AquaticMacros/MacroinvertMatch/Macroi nvertebrateMatchGame.html

35 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Wetlands include marshes, swamps, and bogs Wetlands = systems that combine elements of freshwater and dry land Freshwater marshes = shallow water allows plants to grow above the water’s surface Swamps = shallow water that occurs in forested areas -Can be created by beavers Bogs = ponds covered in thick floating mats of vegetation -A stage in aquatic succession

36 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Wetlands are valuable Wetlands are extremely valuable for wildlife They slow runoff -Reduce flooding -Recharge aquifers -Filter pollutants People have drained wetlands, mostly for agriculture -Southern Canada and the U.S. have lost more than half of their wetlands

37 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Groundwater plays a key role Groundwater = any precipitation that does not evaporate, flow into waterways, or get taken up by organisms -Groundwater makes up one fifth of the Earth’s freshwater supply Aquifers = Porous sponge-like formations of rock, sand, or gravel that hold groundwater Zone of aeration = pore spaces are partially filled with water Zone of saturation = spaces are completely filled with water Water table = boundary between the two zones Aquifer recharge zone = any area where water infiltrates Earth’s surface and reaches aquifers

38 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A typical aquifer

39 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings There are two categories of aquifers Confined or artesian = water-bearing, porous rocks are trapped between layers of less permeable substrate (i.e., clay) -Is under a lot of pressure Unconfined aquifer = no upper layer to confine it -Readily recharged by surface water Groundwater becomes surface water through springs or human-drilled wells Groundwater may be ancient: the average age is 1,400 years

40 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Ogallala Aquifer The world’s largest known aquifer Underlies the Great Plains of the U.S. Its water has allowed farmers to create the most bountiful grain- producing region in the world

41 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings How we use water We have achieved impressive engineering accomplishments to harness freshwater sources -60 % of the world’s largest 227 rivers have been strongly or moderately affected -Dams, canals, and diversions Consumption of water in most of the world is unsustainable -We are depleting many sources of surface water and groundwater

42 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Climate change will cause water shortages Climate change will cause -Altered precipitation patterns -Melting glaciers -Early season runoff -Intensified droughts -Flooding Increasing probability that there will be still less water for more people

43 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We have erected thousands of dams Dam = any obstruction placed in a river or stream to block the flow of water so that water can be stored in a reservoir -To prevent floods, provide drinking water, allow irrigation, and generate electricity -45,000 large dams have been erected in more than 140 nations Only a few major rivers remain undammed -In remote regions of Canada, Alaska, and Russia

44 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A typical dam

45 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings China’s Three Gorges Dam The dam, on the Yangtze River, is the largest in the world -186 m (610 feet) high, 2 km (1.3 mi) wide -Its reservoir stretches for 616 km (385 mi) -Provides flood control, passage for boats, and electricity

46 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drawbacks of the Three Gorges Dam Cost $25 billion to build Is flooding 22 cities and the homes of 1.13 million people Submerging 10,000-year-old archaeological sites Drowning farmland and wildlife habitat Tidal marshes at the Yangtze’s mouth are eroding Pollutants will be trapped China will spend $5 billion to build sewage treatment plants

47 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Benefits and drawbacks of dams Benefits: -Power generation -Emission reduction -Crop irrigation -Drinking water -Flood control -Shipping -New recreational opportunities Drawbacks: -Habitat alteration -Fisheries declines -Population displacement -Sediment capture -Disruption of flooding -Risk of failure -Lost recreational opportunities

48 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Some dams are being removed Some people feel that the cost of dams outweighs their benefits -They are pushing to dismantle dams Rivers with dismantled dams -Have restored riparian ecosystems -Reestablished fisheries -Revived river recreation 500 dams have been removed in the U.S. -Property owners who opposed the removal change their minds once they see the healthy river

49 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Dikes and levees are meant to control floods Flooding is a normal, natural process -Floodwaters spread nutrient-rich sediments over large areas Floods also do tremendous damage to property Dikes and levees (long, raised mounds of earth) along the banks of rivers hold rising waters in channels -The U.S. Army Corps of Engineers has constructed thousands of miles of levees Levees can make floods worse by forcing water to stay in channels and overflow

50 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We divert – and deplete – surface water People have long diverted water to farm fields, homes, and cities The once mighty Colorado River has been extensively dammed and diverted

51 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Colorado River is heavily diverted -What water is left after all the diversions comprises just a trickle into the Gulf of California -On some days, water does not reach the gulf -Diversion has drastically altered the river’s ecology

52 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Aral Sea Once the fourth-largest lake on Earth -It has lost more than 80% of its volume in just 45 years -The two rivers leading into the Aral Sea were diverted to irrigate cotton fields Consequences of a shrinking sea -60,000 fishing jobs are gone -Pesticide-laden dust from the lake bed is blown into the air -The cotton cannot bring back the region’s economy

53 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Can the Aral Sea be saved? People may have begun saving the northern part of the Aral Sea

54 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Inefficient irrigation wastes water Today, 70% more water is withdrawn for irrigation than in 1960 -The amount of irrigated land has doubled -Crop yields can double

55 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Most irrigation is highly inefficient Only 45% of water is absorbed by crops via “flood and furrow” irrigation Overirrigation leads to waterlogging, salinization, and lost farming income Most national governments subsidize irrigation Water mining = withdrawing water faster than it can be replenished

56 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We are depleting groundwater Groundwater is easily depleted -Aquifers recharge slowly -1/3 of world population relies on groundwater As aquifers become depleted -Water tables drop -Salt water intrudes in coastal areas -Sinkholes = areas where ground gives way unexpectedly -Some cities (Venice, Mexico City) are slowly sinking -Wetlands dry up

57 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Will we see a future of water wars? Freshwater depletion leads to shortages, which can lead to conflict -261 major rivers cross national borders -Water is a key element in hostilities among Israel, Palestinians, and neighboring countries Many nations have cooperated with neighbors to resolve disputes

58 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Solutions can address supply or demand We can either increase supply or reduce demand Lowering demand -Politically difficult in the short term -Offers better economic returns -Causes less ecological and social damage Increasing supply -Water can be transported through pipes and aqueducts -It can be forcibly appropriated from weak communities

59 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Desalinization “makes” more water Desalinization = the removal of salt from seawater or other water of marginal quality -Distilling = hastens evaporation and condenses the vapor -Reverse osmosis = forces water through membranes to filter out salts Desalinization facilities operate mostly in the arid Middle East It is expensive, requires fossil fuels, and produces concentrated salty water

60 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The world’s largest reverse osmosis plant Near Yuma, Arizona Intended to reduce the salinity of irrigation runoff Too expensive to operate and closed after 8 months

61 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Agricultural demand can be reduced Look first for ways to decrease agricultural demand -Lining irrigation canals -Low-pressure spray irrigation that spray water downward -Drip irrigation systems that target individual plants -Match crops to land and climate -Selective breeding and genetic modification to raise crops that require less water

62 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Residential demand can be reduced Install low-flow faucets, showerheads, washing machines, and toilets Water lawns at night, when evaporation is minimal Eat less meat Xeriscaping = landscaping using plants adapted to arid conditions

63 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Industrial demand can be reduced Shift to processes that use less water -Wastewater recycling -Excess surface water runoff used for recharging aquifers -Patching leaky pipes -Auditing industries -Promoting conservation/education

64 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Economic approaches to water conservation End government subsidies of inefficient practices -Let the price of water reflect its true cost of extraction Industrial uses are more profitable than agricultural -Less developed countries suffer Privatization of water supplies -May improve efficiency -Firms have little incentive to provide access to the poor Decentralization of water control may conserve water -Shift control to the local level

65 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Freshwater pollution and its control Water for human consumption and other organisms needs to be… -Disease-free -Nontoxic Half of the world’s major rivers are seriously depleted and polluted -They poison surrounding ecosystems -Threaten the health and livelihood of people The invisible pollution of groundwater has been called a “covert crisis”

66 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Nutrient pollution Pollution = the release of matter or energy into the environment that causes undesirable impacts on the health and well-being of humans or other organisms Nutrient pollution from fertilizers, farms, sewage, lawns, golf courses -Leads to eutrophication Solutions -Phosphate-free detergents -Planting vegetation to increase nutrient uptake -Treat wastewater -Reduce fertilizer application

67 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Eutrophication is a natural process, but… Human activities dramatically increase the rate at which it occurs

68 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Pathogens and waterborne diseases Enters water supply via inadequately treated human waste and animal waste via feedlots Causes more human health problems than any other type of water pollution Fecal coliform bacteria indicate fecal contamination of water -The water can hold other pathogens, such as giardiais, typhoid, hepatitis A

69 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Pathogens cause massive human health problems Currently, 1.1 billion people are without safe drinking water 2.4 billion have no sewer or sanitary facilities -Mostly rural Asians and Africans An estimated 5 million people die per year Solutions: Treat sewage Disinfect drinking water Public education to encourage personal hygiene Government enforcement of regulations

70 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Toxic chemicals From natural and synthetic sources -Pesticides, petroleum products, synthetic chemicals -Arsenic, lead, mercury, acid rain, acid drainage from mines Effects include: poisoning animals and plants, altering aquatic ecosystems, and affecting human health Solutions: Legislating and enforcing more stringent regulations of industry Modify industrial processes Modify our purchasing decisions

71 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sediment pollution Sediment can impair aquatic ecosystems -Clear-cutting, mining, poor cultivation practices -Dramatically changes aquatic habitats, and fish may not survive -Solutions: better management of farms and forests; avoid large-scale disturbance of vegetation

72 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Thermal pollution Warmer water holds less oxygen -Dissolved oxygen decreases as temperature increases -Industrial cooling heats water -Removing streamside cover also raises water temperature Water that is too cold causes problems -Water at the bottom of reservoirs is colder -When water is released, downstream water temperatures drop suddenly and may kill aquatic organisms

73 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Point and nonpoint source water pollution Point source water pollution = discrete locations of pollution -Factory or sewer pipes Nonpoint source water pollution = pollution from multiple cumulative inputs over a large area -Farms, cities, streets, neighborhoods The U.S. Clean Water Act -Addressed point sources -Targeted industrial discharge In the U.S., nonpoint sources have a greater impact on quality -Limit development on watershed land surrounding reservoirs

74 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Freshwater pollution sources

75 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Indicators of water quality Scientists measure properties of water to characterize its quality -Biological indicators: presence of fecal coliform bacteria and other disease-causing organisms -Chemical indicators: pH, nutrient concentration, taste, odor, hardness, dissolved oxygen -Physical indicators: turbidity, color, temperature

76 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Groundwater pollution is a serious problem Groundwater is increasingly contaminated, but is hidden from view -Difficult to monitor -Out of sight, out of mind -Retains contaminants for decades and longer -Takes longer for contaminants to breakdown in groundwater because of the lower dissolved oxygen levels

77 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sources of groundwater pollution Some toxic chemicals occur naturally -Aluminum, fluoride, sulfates Pollution from human causes -Wastes leach through soils -Pathogens enter through improperly designed wells -Hazardous wastes are pumped into the ground -Underground storage septic tanks may leak

78 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Agriculture and industries pollute groundwater Agricultural pollution -Nitrates from fertilizers -Pesticides were detected in more than half of the shallow aquifers tested Manufacturing industries and military sites have been heavy polluters

79 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Legislative efforts reduce pollution Federal Water Pollution Control Act (1972) -Renamed the Clean Water Act in 1977 -Illegal to discharge pollution without a permit -Standards for industrial wastewater -Funded sewage treatment plants Because of legislation, the situation is much better than it was Other nations have also reduced pollution

80 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings We treat our drinking water Technology has improved our pollution control The EPA sets standards for more than 80 drinking water contaminants -Local governments and private water suppliers must meet Before water reaches the user -It is chemically treated, filtered, and disinfected

81 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings It is better to prevent pollution It is far better to prevent groundwater contamination than correct it Other options are not as good: -Removing just one herbicide from water costs $400 million -Pumping, treating, and re-injecting it takes too long -Restricting pollutants above aquifers would shift pollution elsewhere Consumers can purchase environmentally friendly products -Become involved in local “river watch” projects

82 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Treating wastewater Wastewater = water that has been used by people in some way -Sewage, showers, sinks, manufacturing, storm water runoff Septic systems = the most popular method of wastewater disposal in rural areas -Underground septic tanks separate solids and oils from wastewater -The water drains into a drain field, where microbes decompose the water -Solid waste needs to be periodically pumped and landfilled

83 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Municipal sewer systems In populated areas, sewer systems carry wastewater -Physical, chemical, and biological water treatment Primary treatment = the physical removal of contaminants in settling tanks (clarifiers) Secondary treatment = water is stirred and aerated so aerobic bacteria degrade organic pollutants -Water treated with chlorine is piped into rivers or the ocean -Some reclaimed water is used for irrigation, lawns, or industry

84 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A typical wastewater treatment facility

85 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Artificial wetlands Natural and artificial wetlands can cleanse wastewater -After primary treatment at a conventional facility, water is pumped into the wetland -Microbes decompose the remaining pollutants -Cleansed water is released into waterways or percolated underground Constructed wetlands serve as havens for wildlife and areas for human recreation -More than 500 artificially constructed or restored wetlands exist in the U.S.

86 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Conclusion Obtaining future supplies of freshwater will be an environmental challenge With expanding population and increasing water usage, we are approaching conditions of widespread scarcity Water pollution is already harming freshwater around the world New approaches can help this situation

87 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review The picture shows a(n) … ? a) Estuary b) Wetland c) Oxbow lake d) River delta

88 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review The area of a lake that contains open water that does not receive sunlight is called the _______zone. a)Littoral b)Benthic c)Limnetic d)Profundal

89 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review A confined aquifer is defined as…? a)An aquifer that traps porous rocks between layers of less permeable substrate b)An aquifer that traps porous rocks under one layer of less permeable substrate c)An aquifer with porous rocks resting on bedrock d)An aquifer with no upper layer

90 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Arid countries tend to use their water mostly for…? a)Developing industries b)Agriculture c)Households d)Export to rich countries

91 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Which of the following statements is not a benefit of dams? a)Habitat alteration b)Power generation c)Crop irrigation d)Shipping

92 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Pollution is defined as “the release of matter or energy into the environment that causes ______”? a)Undesirable impacts on human health b)Undesirable impacts on other organisms c)Undesirable impacts on human well-being d)All of the above are included in the definition

93 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Which of the following is a nonpoint source of water pollution? a)A factory b)Sewer pipes c)Agricultural fields d)All are nonpoint sources

94 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Primary treatment of wastewater includes…? a)Treating water with chemicals b)Stirring and aerating water c)Degradation of wastes by bacteria d)Physical removal of contaminants

95 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Interpreting Graphs and Data What is the relationship between water consumption and the amount of land that is irrigated? a)Irrigation has grown more slowly than demand b)Irrigation and demand have both increased c)Growth of demand and irrigation will slow d)The U.S. does not follow this graph

96 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Interpreting Graphs and Data Which conclusion can you draw from this graph? From The Science behind the Stories a) It is more water efficient to produce vegetables b) It is more water efficient to produce meat c) Vegetable and meat production are relatively alike in water consumption d) There is little correlation between water consumption and our diet

97 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Viewpoints In 2001, angry farmers disobeyed a federal order to divert irrigation water downstream to save endangered species of fish. What should happen to the farmers? a)Nothing; they need the water for their crops b)They should be fined for breaking the law c)They should be paid subsidies so they can continue farming d)They should be paid to plant different crops that do not require so much water

98 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Viewpoints Should cities in dry areas such as Las Vegas be allowed to increase their populations, so that they will require more water? a)Yes; it’s not the American way to limit what cities can do b)Yes, but the people will have to pay the true cost of water c)Yes, but only if the people are required to use drastic conservation measures d)No; enough is enough, and cities in arid environments simply cannot continue growing


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