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Powerpoint presentation given as a lecture to environmental science students studying a unit on water, the water cycle, and water pollution.
Water: Resources and Pollution "Water will be more important than oil this century.” - Former U.N. Secretary General Boutros Boutros Gali 1 Great Plan for the Transformation of Nature • During the late 1940s, Joseph Stalin proposed a plan in the Soviet Union to prevent a repeat of drought- caused famine in 1947 that killed nearly a million people. • A wide variety of ideas were implemented during the next two decades. 2 Transformation of Nature • Windbreaks, or lines of trees, were built to reduce soil erosion. A windbreak built into a North Dakota Farm. Source: Wikimedia 3 Transformation of Nature • A network of irrigation canals were built to divert water from two rivers into a desert region, to encourage the cultivation of crops such as rice, wheat, and cotton. • The rivers normally fed into the Aral Sea. 4 The Aral Sea • In the 1950s, the Aral sea was one of the four largest lakes in the world, with an area of 26,300 square miles. • The entire lake was part of the U.S.S.R., in the countries that today are Kazakhstan and Uzbekistan. 5 Irrigation Canals • The irrigation canals were poorly built and uncovered, allowing about half of the water to evaporate or leak into the surrounding soil. • The Aral sea, deprived of its main water supply, began to shrink in 1961. Satellite imagery of the Aral Sea shrinkage from 1961-2011. 6 Salination • The amount of water lost by the Aral Sea would completely fill Lakes Erie and Ontario. • The salinity of the remaining water has increased to 2-3x that of ocean water. • The drainage of the lake has An abandoned ship in Aral, Kazakhstan. also exposed pesticides, herbicides, and other industrial pollutants on the bottom. 7 Why is Water Important? • Necessary for all life to exist. • Next to antibiotics, single biggest increase in human life span is due to having access to clean water. • Diseases/toxins transmitted by contaminated water: Intestinal disease (cholera/dysentery) Arsenic poisoning Mercury poisoning 8 Hydrologic Cycle • The water on earth is continually recycled. • The hydrologic cycle describes this circulation: 1. Water evaporates from wet land, lakes, or oceans and transpires from plants as they dry up. 2. Enters the atmosphere, which is much colder, condenses and falls as precipitation. 3. Moves underground by infiltration or runs off into rivers, lakes, or the ocean. 9 10 Earth’s Water Budget All water Oceans and saline lakes 97.4% Fig. 11-2, p. 238 Earth’s Water Budget All water Oceans and saline lakes 97.4% Fig. 11-2, p. 238 Earth’s Water Budget All water Fresh water Readily accessible fresh water Groundwater 0.592% Biota 0.0001% Rivers Lakes 0.0001% 0.007% Fresh water 0.014% 2.6% Atmospheric Oceans and Ice caps Soil water vapor saline lakes and glaciers moisture 0.001% 97.4% 1.984% 0.005% Fig. 11-2, p. 238 MAJOR WATER COMPARTMENTS • Groundwater Largest available (non-frozen) source of fresh water. Water moves underground through infiltration; percolation through the soil and into fractures and permeable rocks. - Zone of Aeration - Upper soil layers that hold both air and water. - Zone of Saturation - Lower soil layers where all spaces are filled with water. - Water Table - Top of Zone of Saturation 14 Infiltration 15 Groundwater • Aquifers - Porous layers of sand, gravel, or rock lying below the water table. Aquifers are separate from groundwater; they are usually isolated by layers of rock. Artesian Well – Directly tapes into an aquifer as a source of water. 16 Groundwater • The recharge zone is an area where water infiltrates and refills an aquifer. Recharge rate is often very slow, depending on the size of the recharge zone and how often it rains there. 17 MAJOR WATER COMPARTMENTS CONT’D • Wetlands Play a vital role in hydrologic cycle. Wetlands have an unusually high amount of plant growth. Benefits include: - Stabilizes soil, preventing erosion - Slows down surface runoff, allowing more aquifer recharge. - Can hold excess water during flooding. 18 MAJOR WATER COMPARTMENTS CONT’D • Rivers and Streams Formed from water that does not infiltrate, but runs off from surrounding land. May also be formed by melting glaciers. Each of the major rivers in Southeast Asia are fed by Himalayan glaciers. 19 MAJOR WATER COMPARTMENTS CONT’D • The Atmosphere Among the smallest water reservoirs; only contains 0.001% of the total water supply. Has most rapid turnover rate. Water in the atmosphere does not remain there. - Redistributes water all over the earth. 20 Water Use • Consumption – Water that is withdrawn and no longer available for use because it has evaporated, been consumed by animals or plants, or discharged to a different location. 21 Quantities of Water Used • Water use has been increasing twice as fast as population growth over past century. Worldwide, agriculture claims about 70% of total water withdrawal. - In many developing countries, agricultural water use is extremely inefficient and highly consumptive. Worldwide, industry accounts for about 25% of all water use. - Cooling water for power plants is single largest industrial use. 22 Water Withdrawal 23 FRESHWATER SHORTAGES • Areas that consume more water than typically falls as precipitation are considered to have water stress. 24 A Precious Resource • Currently, 45 countries cannot meet the minimum essential water requirements of their citizens. • Will increase to 60 countries by 2050. 25 Depleting Groundwater • Groundwater is the source of nearly 40% of fresh water in the U.S. • Withdrawing water faster than it can be replenished leads to a cone of depression in the water table. • If this continues, the water table can be completely withdrawn. 26 Depleting Groundwater 27 Depleting Groundwater Cont’d • Withdrawing large amounts of groundwater in a small area causes porous formations to collapse, resulting in subsidence. 28 INCREASING WATER SUPPLIES • Seeding Clouds • Add silver iodide or dry ice to clouds • Inconsistent results 29 INCREASING WATER SUPPLIES • Towing Icebergs Cost • Desalination Removal of salt from ocean water Requires a high input of energy 30 INCREASING WATER SUPPLIES CONT’D • Dams, Reservoirs, and canals can be constructed to make the water supply more consistent or divert water to dry areas. This could result in the displacement of people, flooding of ecosystems. Evaporation rates increase as water is slowed. Any dissolved nutrients present in the water sink into the reservoir. 31 Dams, Reservoirs, and Canals Displacement of People - Any villages present where the new reservoir will fill in must be evacuated. - The Three Gorges Dams in China will force relocation of over a million people. Evaporation, Leakage, Siltation - Evaporative losses from Lake Mead and Lake Powell on the Colorado River is about 1km3 per year (264 billion gallons). - Dams slow water flow, allowing silt (nutrients) to drop out. 32 Dams, Reservoirs, and Canals • Loss of Free-Flowing Rivers Fish and other organisms will no longer be able to travel freely up and down that part of the river. 33 Evaporative losses from Lake Mead and Lake Powell on the Colorado River is about 1km3 per year (264 billion gallons). Domestic Conservation • Estimates suggest many societies could save as much as half of current domestic water usage without great sacrifice or serious change in lifestyle. What are the biggest domestic uses of water? 35 WATER POLLUTION • Any physical, biological, or chemical change in water quality that adversely affects living organisms can be considered pollution. Point Sources - Discharge pollution from specific locations. - Factories, power plants, oil wells Non-Point Sources - Scattered or diffuse, having no specific location of discharge. - Agricultural fields, feedlots, golf courses 37 Heavy Metal Pollutants • Many metals such as mercury, lead, cadmium, and nickel are highly toxic. • They are highly persistent and tend to bioaccumulate in food chains. • Biggest sources: Mercury released from incinerators and coal-burning power plants. Mine drainage and leaching. 38 Other Inorganic Pollutants • Nonmetallic Salts Biggest source is road salt used during the winter. When the snow melts, the salt runs off into nearby rivers or lakes. • Acids and Bases Changes the pH of the water. Aquatic organisms are very sensitive to pH changes. 39 Organic Chemicals • Organic compounds are complex molecules that contain carbon. • Two most important sources of toxic organic chemicals in water are: Improper disposal of industrial and household wastes. Runoff of pesticides from private lawns and farms. 40 Organic Chemicals • PCBs are one of the biggest and most persistent examples of organic chemical pollution Used for multiple electronic, wiring, adhesive, and lubrication applications. • PCBs are… Mutagenic Endocrine disruptors (mimic estrogen) Carcinogenic 41 This is a guide to Lake Michigan fish. The fish with the highest level of contamination tend to be larger or bottom- feeders. 42 Sediment Pollution • Sediment is soil and rock particles that have entered water due to erosion. • Erosion is normal, but can be accelerated by human activities. • Sediment is beneficial (nourishes plants found in floodplains) in small amounts but can be harmful (smother aquatic life) when there is too much. 43 Thermal Pollution • Thermal pollution is dumping water into a river, lake, or sea that is either much warmer or much colder than normal. Oxygen levels in water decreases as temperatures increase. 44 Groundwater Contamination • Groundwater is highly susceptible to pollution due to its location underground. • Example sources: - Leftover mining waste - Radioactive waste - Organic waste (manure) - Unsealed municipal waste (landfills) - Electricity generation waste (fossil fuels) - Oil and gas drilling 45 Groundwater Pollution 46 Hydraulic Fracturing • Hydraulic fracturing, or “fracking”, is a controversial technique used to extract natural gas from rock formations that are not very permeable. Examples: Shale and coal beds. 47 Natural Gas Deposits • Fracturing has become an increasingly popular tool for extracting natural gas, especially with the discovery of the methane- rich Marcellus Shale. 48 The Fracturing Process • Fracturing fluid is pumped into a narrow hole drilled into the rock formation. • The pressure created from this fluid causes the rock formation to crack. • Sand is injected afterwards to fill the cracks, because it is more permeable and allows the methane to seep out. Most of the mixture injected into the rock formation is rock and sand, however… 49 Fracturing Fluid • A number of hazardous chemicals are also present in the fracturing fluid. These include carcinogens and endocrine disruptors. In a study published in 2010, the EPA discovered contaminants in groundwater. The gas industry claims that it is impossible for these fluids to enter groundwater. 50 2005 Energy Policy Act • The EPA has been unable to investigate contamination due to fracturing for two reasons: 1. The 2005 Energy Policy Act provides the industry exemption from the Clean Water and Drinking Water Acts. 2. The specific chemicals used in fracturing are protected under copyright law as trade secrets. 51 Incidents Resulting from Fracturing • Methane gas has entered drinking water supplies in Dimock, PA. Caused a water well explosion. • A well explosion in Clearfield, PA sent 35,000 gallons of fracturing fluid into the surrounding forests. • Another well in Leroy, PA experienced a leak and entered the groundwater. 52 Impaired Waters • Impaired waters are rivers, lakes, and estuaries that cannot fully support their aquatic biological communities. • Top three causes: Excess sediment Nutrients (nitrogen and phosphorous) Pathogenic microorganisms 53 Water Quality Today Source: US EPA http://pubs.usgs.gov/fs/FS-130-01/ 54 Water Testing Standards • The EPA requires that local water treatment plants provide yearly reports to residents listing any contaminants found in the drinking water supply. • Must be tested for microbes several times a day. Bottled water has much less strict requirements. 55 Tap Water Quality 56 Source: Environmental Working Group; www.ewg.org Local Tap Water Contaminants • Chlorine treatment byproducts – Bromodichloromethane,Dibromochloromethane, haloacetic acids, bromoform, chloroform Formed when chlorine reacts with organic matter found in water. Legal limit for these pollutants is 100 parts per billion. LD50 of chloroform is about 900mg/kg. 57 Bottled Water? • Spring water – From an underground source. • Purified water – Treated with distillation, ozonation, or reverse osmosis. • Mineral water – Naturally contains certain amounts of minerals from the source. • Sparkling water – Naturally containing carbon dioxide • Artesian water – Source is a confined aquifer. • Municipal water – Tap water. 58 Water Filtration • Reverse Osmosis - Pressurized water is sent through a selective membrane filter. • Distillation – Water is boiled; Steam is collected and bottled. • Ozonation – Ozone is bubbled through water to kill microorganisms. 59 Gold Mining • Of all the metals that are mined, gold may be the most polluting. • Heap Leaching – A mining process that extracts precious metals (such as gold) by pouring a cyanide solution over the ore. The cyanide dissolves the gold or silver in the crushed ore. The liquid is collected and the metals are extracted from it. The cyanide is reused and the ore is dumped. 60 Heap Leaching 61 Ocean Pollution • In spring 2010, a beached whale died off the coast of Seattle. • Inside the whale’s stomach was found… A pair of sweatpants A golf ball 20 plastic bags Surgeon’s gloves Duct tape Plastic pieces • Did not play a role in whale’s death 62 Ocean Pollution • The two biggest ocean pollutants: Oil Plastics • Estimated 6 million metric tons of plastic bottles, packaging material, and other litter tossed from ships into the ocean annually. Plastic bottles gradually break down into smaller pieces. They never fully decompose because they are synthetic and not found in nature. 63 Ocean Pollution 64 Ocean Pollution • Most of the oil in the ocean comes from nonpoint sources. • The biggest one is people dumping used motor oil from their cars into the sink or storm drains. Cause more long-term buildup. • The biggest point source is oil spills or leaks from oil platforms or tankers. The point sources are much more concentrated and cause much more short- term damage. 65 Oil Spills • Exxon Valdez (1989) – One of the worst incidents of water pollution to ever occur. High volume of oil spilled Remote location and a poor cleanup response Thousands of sea birds, sea mammals, and fish were killed. 66 Exxon Valdez and Tanker Design • Resulted in the Oil Pollution Act of 1990 Mandated a double-hull design for oil supertankers by 2015. Would have reduced the oil spilled by Exxon Valdez by 60% 67 Deep Water Horizon • The Deepwater Horizon was a floating oil rig in the Gulf of Mexico contracted to British Petroleum. • An explosion occurred on this rig in April of 2010, resulting in the worst oil spill ever. 68 Deep Water Horizon • The rig was working drilling and preparing a well deep in the seabed of the Gulf of Mexico when a sudden surge of oil and natural gas traveled up through the rig, causing a blowout at the surface. 69 Deepwater Horizon • Even as the flames were contained, the oil continued to gush out at a rate of about 60,000 barrels per day. 70 Deepwater Horizon 71 Aftermath • Damage from the oil spill was the most intense in three areas: The beaches of the nearby states, especially Louisiana, Missisippi, and Alabama. Underwater; Oil plumes stretched as long as 10 miles in some spots. The sea floor; Oil and residue 2-5 inches thick has been recorded in some areas. 72 Laws and Lawsuits • BP reported actual cleanup costs of $3.12 billion. • The Oil Pollution Act of 1990 also limited the BP’s liability for non-cleanup costs to $75 million unless gross negligence can be proven. • BP estimates that its total costs of cleanup, recovery, litigation, and restitution will be about $40 billion. 73 Infectious Agents • Main source of waterborne pathogens is untreated and improperly treated human waste. Animal wastes from feedlots and fields is also an important source of pathogens. • In developed countries, sewage treatment plants and pollution-control devices have greatly reduced pathogens. Coliform bacteria - Intestinal bacteria. - Escherichia coli (E. coli) 74 Oxygen-Demanding Wastes • Water with an oxygen content > 6 ppm will support desirable aquatic life. Water with < 2 ppm oxygen will support mainly detritivores and decomposers. • Oxygen is added to water by diffusion from wind and waves, and by photosynthesis from green plants, algae, and cyanobacteria. Oxygen is removed from water by respiration and oxygen-consuming processes. 75 Oxygen-Demanding Wastes Cont’d • Biochemical Oxygen Demand - Amount of dissolved oxygen consumed by aquatic microorganisms. Dissolved Oxygen Content - Measure of dissolved oxygen in the water. • Effects of oxygen-demanding wastes on rivers depend on volume, flow, and temperature of river water. Oxygen Sag - Oxygen levels decline downstream from a pollution source as decomposers metabolize waste materials. 76 Oxygen Sag 77 Plant Nutrients and Cultural Eutrophication • Oligotrophic - Bodies of water that have clear water and low biological productivity. • Eutrophic - Bodies of water that are rich in organisms and organic material. Eutrophication - Process of increasing nutrient levels and biological productivity. - Cultural Eutrophication - Increase in biological productivity and ecosystem succession caused by human activities. 78 79 80 WATER LEGISLATION • Clean Water Act Enacted in 1972, amended in 1977 and 1987. Covers only “relatively permanent” waters, including streams, oceans, rivers, and lakes. Point-source pollutants cannot be discharged into waters without permits from their state. Does not address non-point pollutants. 81 POLLUTION CONTROL • Source Reduction Cheapest and most effective way to deal with pollution is avoid producing it or releasing it into the environment. 82
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