Water Pollution Chapter 22 Review Key Concepts Types

Water Pollution Chapter 22 Review

Key Concepts Ø Types, sources, and effects of water pollutants Ø Major pollution problems of surface water Ø Major pollution problems of groundwater Ø Reduction and prevention of water pollution Ø Drinking water quality

Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms. Water is polluted by: • Infectious bacteria • Inorganic and organic chemicals, • Excess heat

• The WHO estimates that 3. 4 million people die prematurely each year from waterborne diseases. • In the U. S. , an estimated 1. 5 million people a year become ill from infectious agents.

Scientists monitor water quality by using bacterial counts, chemical analysis, and indicator organisms. • One method of measuring water quality involves measuring the number of colonies of fecal coliform bacteria present in a water sample. • Drinking water should not contain any colonies/100 milliliters, and safe swimming water should not have more than 200 colonies/100 milliliters. • A new field of science called bacterial source tracking (BST) uses molecular biology techniques to determine subtle differences in strains of E. coli based on their animal host.

• Scientists measure biological oxygen demand (BOD), the amount of dissolved oxygen consumed by aquatic decomposers. • Chemical analysis includes checking inorganic and organic chemicals present, sediment content, and turbidity of water. • Indictor species are living organisms that are monitored to determine levels of pollution. • Genetic techniques are being used to develop organisms that will glow in the presence of specific pollutants such as toxic heavy metals in the ocean and carcinogens in food.

Types, Effects and Sources of Water Pollution Ø Point sources Ø Nonpoint sources Ø Water quality Refer to Tables 22 -1 and 22 -2 p. 492 and 493 Fig. 22 -3 p. 494

• Point sources discharge pollutants at specific locations through drainpipes, ditches, or sewer lines into bodies of surface water. • These sources are easy to identify, monitor, and regulate. • Non-point sources are scattered and diffuse and can’t be traced to any single site of discharge. Such things as runoff from croplands, livestock feedlots, etc. are nonpoint sources. • It is difficult and expensive to identify and control these discharges from diffuse

Point and Nonpoint Sources NONPOINT SOURCES Rural homes Cropland Urban streets Animal feedlot Suburban development POINT SOURCES Factory Wastewater treatment plant Fig. 22 -4 p. 494

Top Sources: • Agricultural activities are the leading cause of water pollution from erosion, overgrazing, fertilizers and pesticides, and excess salt from irrigated soils. • Industrial facilities are another large source of water pollution • mining is a third source.

• One of every five people in the world lacks access to safe drinking water. • Ninety-five percent of people in developed countries and 74% of people in developing countries have access to clean drinking water.

Stream Pollution • Streams can recover from moderate levels of degradable water pollutants if the flows are not reduced. • A combination of dilution and biodegradation can allow recovery of stream pollution if they are not overloaded, or have reduced flow due to damming, agricultural diversion, or drought. • The breakdown of pollutants by bacteria creates an oxygen sag curve. Organisms that have a high oxygen demand can’t survive in the curve. • Volume of the stream, volume of wastes entering, flow rate, temperature, and p. H levels all affect how great a sag curve is produced.

Pollution of Streams Ø Oxygen sag curve Ø Factors influencing recovery Fig. 22 -5 p. 496

Pollution of Freshwater Lakes • Lakes have little flow and so are less effective at diluting pollutants that enter them. • Lakes and reservoirs are often stratified into layers with little vertical mixing, and they also have very little flow occurring. It may take from 100 years to flush and change water in lakes and reservoirs. • Lakes and reservoirs are much more vulnerable to runoff contamination of all kinds of materials. • Chemical concentrations build up as they pass through the food webs in lakes.

• Natural nutrient enrichment of lakes from runoff is called eutrophication. The amount of natural eutrophication depends on the composition of the surrounding drainage basin. • Natural eutrophication can enrich the abundance of desirable organisms, but cultural eutrophication occurs near urban or agricultural areas and can lead to serious pollution problems.

Supply of Water Resources Freshwater 2. 6% Readily accessible freshwater Groundwater 0. 592% Biota 0. 0001% 0. 001% Lakes 0. 007% Ice caps and glaciers 1. 984%% 0. 014% Oceans and Saline Lakes 97. 4% Soil moisture 0. 005% Rivers 0. 0001% 0. 001% Atmospheric water vapor 0. 0001% 0. 001% Fig. 15 -2 p. 307

• During hot weather or drought, “blooms” of organisms can reduce lake productivity. • Reduced sunlight and the subsequent decomposition of the “blooms” increase populations of bacteria and decreases dissolved oxygen available. Fish kills can occur, and the problem can become so bad that anaerobic bacteria take over. • The EPA states that about one-third of 100, 000 medium to large lakes and 85% of large lakes near major population centers in the U. S. have some amount of cultural eutrophication.

• Cultural eutrophication also occurs in coastal water, enclosed estuaries, and bays due to runoff. • Cultural eutrophication can be reduced or prevented by banning or limiting phosphates in detergents and using advanced treatment methods to remove nitrates and phosphates from wastewater, and by use of soil conservation to reduce runoff. • Cleanup of lakes includes removing excess weeds, controlling plant growth, and pumping air through lakes and reservoirs to avoid oxygen depletion. • Pollution prevention is less expensive than control methods.

Pollution of Lakes Eutrophication Fig. 22 -7 p. 499

Case Study: The Great Lakes Fig. 22 -8 p. 500

Groundwater Pollution: Causes Ø Low flow rates Ø Few bacteria Ø Low oxygen Ø Cold temperatures Hazardous waste injection well Coal strip mine runoff Pesticides De-icing road salt Pumping well Waste lagoon Buried gasoline and solvent tank Cesspool septic tank Gasoline station Water pumping well Landfill Accidental spills Sewer ifer Leakage from faulty casing aqu Discharge r ate r w e h uif res Confined aquifer q f a r ed e t n i a f con shw Groundwater e n r U df e flow n nfi o C Fig. 22 -9 p. 502

Groundwater is vulnerable to contamination because it can’t effectively cleanse itself and dilute and disperse pollutants

Groundwater Pollution Prevention Ø Monitor aquifers Ø Find less hazardous substitutes Ø Leak detection systems Ø Strictly regulating hazardous waste disposal Ø Store hazardous materials above ground

• Prevention is the most effective and affordable way to protect groundwater from pollutants. • Figure 22 -10 lists ways to prevent and clean up groundwater contamination, not an easy task nor cheap. • Underground tanks in the U. S. and some other developed countries are now strictly regulated. Old, leaky tanks are being removed, and the surrounding soils are being treated.

Ocean Pollution Fig. 22 -11 p. 504

Case Study: Chesapeake Bay Ø Largest US estuary Ø Relatively shallow Ø Slow “flushing” action to Atlantic Ø Major problems with dissolved O 2 Fig. 22 -13 p. 506

Oil Spills Ø Sources: offshore wells, tankers, pipelines and storage tanks Ø Effects: death of organisms, loss of animal insulation and buoyancy, smothering Ø Significant economic impacts Ø Mechanical cleanup methods: skimmers and blotters Ø Chemical cleanup methods: coagulants and dispersing agents

• Point sources account for about 60% of the phosphates. Nonpoint sources account for about 60% of the nitrates. • Between 1985 and 2000, there has been a 27% decline in phosphorus levels, 16% drop in nitrogen levels, and a recovery of grasses growing on the bottom of the bay. • Reduction in funding has slowed the progress of cleanup in the bay, but it demonstrates what can be done with cooperation of diverse groups.

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• Parts of the world’s oceans are dump sites for a variety of toxic materials, sewage, and garbage from ships • Dumping industrial wastes off U. S. coasts has stopped, The London Dumping Convention of 1972 stated that 100 countries agreed not to dump highly toxic pollutants and high-level radioactive wastes in the open sea. In 1994, it became a permanent ban.

• Oil pollution can have a number of harmful ecological and economic effects, but most disappear within 3– 15 years. • A number of factors are important when determining the effects of oil on ocean ecosystems. • Volatile organic hydrocarbons in oil kill some aquatic organisms, especially the larval forms. • Tarlike globs coat bird feathers and fur of marine mammals, and these organisms then either drown or die from loss of body heat.

• Bottom-dwelling organisms are killed when heavy components sink to the sea floor.

• Only about 15% of the oil spilled can be recovered with current techniques, so prevention is the best strategy. • Methods available include mechanical methods such as floating booms, skimmers, and absorbent devices. • Chemical methods use coagulating agents for clumping oil and dispersing agents to break up slicks. Fire can also burn off floating oil. • Biological methods are being developed to utilize bacteria that are able to degrade oil. It is less expensive and more effective than other methods. • The Oil Pollution Act of 1990 set up a trust fund of $1 million per spill for cleanup. By 2015, all oil tankers operating in U. S. waters must be double hulled.

Solutions: Preventing and Reducing Surface Water Pollution Nonpoint Sources Point Sources Ø Reduce runoff Ø Clean Water Act Ø Buffer zone vegetation Ø Water Quality Act Ø Reduce soil erosion

• Preventing or reducing pollution from the land from streams is the key to protecting the oceans.

Preventing and Reducing Surface Water Pollution • Reduce non-point pollution by preventing it from reaching bodies of surface water. • Agricultural non-point pollution can be reduced by reducing soil erosion, reforestation of watersheds, keeping cover crops on farmland, reducing fertilizer use or using slow-release fertilizer, and planting buffer zones between farmland surface water nearby.

• Most developing countries do not have laws to set water pollution standards. • The Clean Water Act sets standards for allowed levels of key water pollutants and requires polluters to obtain permits that specify the amounts of pollutants they can discharge into aquatic systems. • Most cities in developing countries discharge 80– 90% of untreated sewage into rivers, lakes, and streams used for drinking water, bathing, and washing

• Septic tanks and various levels of sewage treatment can reduce point-source water pollution. • About one-fourth of homes in the U. S. are served by septic tanks. • Most urban areas are served by sewage treatment plants. • Some 1, 200 cities have combined storm runoff and sewer lines because it is cheaper. These systems can overflow and discharge untreated sewage directly into surface water with too many users or when there is a heavy storm. • Aging sewer systems and combined sewer systems in the U. S. are estimated to cost $10 billion a year for 10 years to install dual systems, add capacity, and repair the aging sewer network.

Technological Approach: Septic Systems Ø Require suitable soils and maintenance Fig. 22 -15 p. 510

• Raw sewage generally undergoes one or two levels of treatment. • Primary sewage treatment is a physical process that removes grit, floating objects, and suspended solids. A settling tank allows suspended solids to settle out as sludge. • Primary treatment removes about 60% of suspended solids and 30– 40% of organic wastes, but no phosphates, nitrates, salts, radioisotopes, or pesticides. • Secondary sewage treatment is a biological process where aerobic bacteria remove up to 90% of dissolved and biodegradable, oxygendemanding organic wastes.

• A combination of primary and secondary treatment removes 95– 97% of the suspended solids and oxygen-demanding organic wastes, 70% of most toxic metal compounds, 70% of phosphorus, 50% of nitrogen, and 5% of dissolved salts. • Most U. S. cities have combined primary and secondary sewage treatment plants.

• Tertiary sewage treatments are a third level of cleanup. Here, a combination of chemical and physical processes remove specific pollutants left by the other methods. This is expensive and used to treat only 5% of the wastewater in the U. S. • Water is bleached to remove colors and then disinfected to kill disease-causing bacteria and some viruses. Chlorination is the usual method of disinfection. • Ozonation and use of ultraviolet light are increasing as methods of disinfection.

Technological Approach: Sewage Treatment Ø Physical and biological treatment Fig. 22 -16 p. 511

Technological Approach: Advanced (Tertiary) Sewage Treatment Ø Uses physical and chemical processes Ø Removes nitrate and phosphate Ø Expensive Ø Not widely used Reed Treatment http: //images. google. com/imgres? imgurl=http: //www. johnstonsmith. co. uk/images/services/reed_bed_tertiary. gif&imgref url=http: //www. johnstonsmith. co. uk/fact 17. html&usg=__a. ETvt. P 9 ml. Qe-kxm. TJ 0 hx. Ysajls=&h=160&w=533&sz=9&hl=en&start=8&tbnid=KBi. MXXQ_l. TZETM: &tbnh=40&tbnw=132&prev=/im ages%3 Fq%3 DTertiary%2 BSewage%2 BTreatment%26 gbv%3 D 2%26 hl%3 Den%26 sa%3 DG

• Preventing toxic chemicals from reaching sewage treatment plants would eliminate these from sludge and water that is discharged. • Require industries and businesses to remove toxic and hazardous wastes from water sent to sewage treatment plants; encourage reduction or elimination of toxic chemical use and waste.

Technological Approach: Using Wetlands to Treat Sewage Fig. 22 -18 p. 513

• Water pollution laws have significantly improved water quality in many U. S. streams and lakes, but more needs to be done. • Between 1992 and 2002, American communities served by water systems meeting federal guidelines increased from 79% to 94%. • Fishable and swimmable streams increased from 36% to 60% of those tested. • Topsoil loss through runoff was cut by 111 billion metric tons annually. • Annual wetland losses decreased by 80%.

Drinking Water Quality Ø Purification of urban drinking water Ø Protection from terrorism Ø Purification of rural drinking water Ø Safe Drinking Water Act Ø Maximum contaminant levels (MCLs) Ø Bottled water

Drinking Water Quality • Centralized water treatment plants can provide safe drinking water for city dwellers. Water is settled, filtered, and chlorinated to meet government drinking standards. • The U. S. is upgrading on water purification and delivery systems. This is such a vast system that it is hard to secure, but also difficult to adequately poison. Both chemical and biological indicators are being developed to indicate a contamination problem.