20-4 What are the Major Water Pollution Problems Affecting Oceans?

Water PollutionChapter 20Dave SangNora Tibbetts20-1 What are the Causes and Effects of Water Pollution?Causes of Water PollutionWater pollution - any chemical, biological, or physical change in water quality that harms living organisms or makes water unsuitable for desired uses.Agricultural activities - leading causeIndustrial facilitiesMiningParking lotsWidespread use of human-made materials (plastics, etc.)Climate change as a result of global warmingPoint SourcesPoint sources - discharge pollutants at specific locations through drain pipes, ditches, or sewer lines into bodies of surface water.Examples: factories, sewage treatment plants, underground mines, oil tankersLocated at specific places, and are easy to identify, monitor, and regulate. Many developed countries have laws that help to control point-source pollution.Nonpoint SourcesNonpoint sources - are broad, and diffuse areas, rather than points, from which pollutants enter bodies of surface water or air.Examples: runoff of chemicals and sediments from cropland, livestock feedlots, logged forests, urban streets, parking lots, lawns, golf courses Difficult and expensive to identify and control such discharges, so not much progress has been made. Effects of Water PollutionExposure to infectious disease organisms (pathogens) mostly through contaminated drinking water. 3.2 million people die prematurely each year as a result of contaminated drinking water.An average of 8,700 premature deaths a day.20-2What are the Major Water Pollution Problems in Streams and Lakes?Water Pollution Problems in Streams Streams can cleanse themselves if we do not overload them:Undergo a natural recovery processCan remove biodegradable wastes, but not slowly degradable and non-degradable pollutantsThe breakdown of biodegradable wastes by bacteria depletes dissolved oxygen and creates an oxygen sag curveOhios Cuyahoga RiverWater pollution control laws enacted in the 1970s have greatly increased the number and quality of waste water treatment plants in the United States and most other developed countries. Extremely polluted with flammable chemicals. Prompted by a highly publicized photo of the burning river in 1969, elected officials enacted laws that limited the discharge of industrial wastes into the river and into local sewage systems and provided funds to upgrade sewage treatment facilities.Today, river is cleaner, no longer flammable, and highly used by boaters and anglers. Successful use of bottom-up pressure by citizens.

Indias Ganges RiverViewed as a holy river.Each day, large numbers of Hindus bathe, drink from, or take a dip in the river for religious reasons.Highly polluted, yet 350 million people live in the Ganges River Basin.Hindus believe in cremating the dead to free the soul and throwing the ashes into the river.Indian government plans to build waste treatment plants to ease pollution.

Water Pollution Problems in LakesGenerally less effective at diluting pollutants than streams are because:Often contain stratified layers that undergo little vertical mixingHave little or no flowVery vulnerable to contamination by runoffContaminants can kill bottom life and fish and birds that feed on contaminated aquatic organisms.Cultural EutrophicationCultural eutrophication - over nourishment of aquatic ecosystems with plant nutrients (mostly nitrates and phosphates) because of human activities such as agriculture, urbanization, and discharges from industrial plants and sewage treatment plants. Produces dense growths or blooms of organisms like algae and cyanobacteria during hot weather or drought.Reduce lake productivity.85% of the large lakes near major U.S. population centers have some degree of cultural eutrophication.

Prevention and Reduction of Cultural EutrophicationLuckily, lakes can usually recover from cultural eutrophication.Use advanced (and expensive) waste treatment to remove nitrates and phosphates before wastewater enters lakes.Mechanically remove excess weeds.Control undesirable plant growth with herbicides and algicides.Pump air through lakes and reservoirs to prevent oxygen depletion.20-3What are the Major Pollution Problems Affecting Groundwater and Other Drinking Water Sources?Major Pollution Problems Affecting GroundwaterCommon pollutants can seep into groundwater from numerous sources.Contaminates are not diluted and dispersed effectively. Much lower concentrations of dissolved oxygen and smaller populations of decomposing bacteria.The cold temperatures of groundwater slow down chemical reactions that decompose wastes.Can take decades to thousands of years for contaminated groundwater to cleanse itself of slowly degradable wastes (like DDT). On a human time scale, non degradable wastes (like toxic lead and arsenic) remain in the water permanently.Protecting GroundwaterTreating a contaminated aquifer involves eliminating the source of pollution and drilling monitoring wells to determine how far, in what direction, and how fast the contaminated plume is moving.A computer model is used to project future dispersion of the contaminant in the aquifer.Develop and implement a strategy to clean up the contamination.Preventing contamination is the least expensive and most effective way to protect groundwater sourcesPurifying Drinking WaterComplex Techniques:Is usually stored in a reservoir and treated in a purification plant in developed countries. Countries like Japan are developing plants that process sewer water into drinking water.El Paso, Texas: 40% of drinking water comes from recycling and purifying waste water.Orange Country, California: completed the worlds largest plant devoted to making sewer water as pure as distilled waterSimple Techniques:Exposing a clear plastic bottle filled with contaminated water to intense sunlightNanofilters to clean contaminated waterLifeStraw

Laws Protecting Drinking Water QualityU.S. Safe Drinking Water Act of 1974 - requires the EPA to establish national drinking water standards, called maximum contaminant levels, for any pollutants that may have adverse effects on human health.Despite this, the UN estimates that 5.6 million Americans drink water that does not meet EPA standards. Health scientists call for strengthening the U.S. Safe Drink Water ActIs Bottled Water the Answer?Between 1976 and 2006, average bottled water consumption per person in the US increased from 7.5 liters (2 gallons) to 113 liters (30 gallons) a year.About one-fourth of it is ordinary tap water in a bottle.Bacteria or fungi contaminate about 40% of bottled water. Many bottles are thrown away without being recycled.Manufacture of plastic water bottles emits toxic gases and liquids.Greenhouse gases and other air pollutants are emitted by the fossil fuels burned to make and to deliver bottled water to suppliers.

20-4What are the Major Water Pollution Problems Affecting Oceans?Ocean Pollution is growing and poorly understoodAbout 40% world population lives on coastsThat population will double by 2050Ocean pollution has a large effect85% of sewage in developing countries is dumped untreated into oceansCruise ships also dump tons of waste into oceansThis pollution creates and spreads diseaseRunoffs release nitrates and phosphates into the water, creating algae bloomsAlgae blooms deplete oxygen and kill ocean animalsThey also poison seafood, harming humansNorthern Gulf of MexicoCollects agricultural runoff for 31 statesHas large zone of depleted oxygen due to eutriphicationMany attempts to reduce sizeAll failed, and zone is still growingScientists fear soon it will be uninhabitable

Ocean Oil is a Serious ProblemOil spills and blowouts spew large amounts of oil into the oceanCostly to clean upMost oil pollution comes from leaks from urban runoffOil immediately kills many larvaeOil stuck of birds causes them to drownRecovery from refined oil usually take triple the time as crude oilOil slicks on beaches can destroy fishing and tourist economiesOil spills can be mechanically cleaned up (booms/skimmers), but only about 15% effectivePreventing pollution is the most important goal (double hull)

20-5How Can We Best Deal with Water Pollution?We Need to Reduce Surface Water Pollution from Nonpoint SourcesFarmers keep soil vegetated to prevent erosionUse slow release fertilizer and use buffers to prevent runoffUse manure for fertilizerUse less pesticides and use IPM

Laws can Help Reduce Water Pollution from Point SourcesFederal Pollution Control ActClean Water ActWater Quality ActSets standards for pollutant limitsEPA : discharge traing policyBuy credits from other permit holdersWould require heavy scrutiny and gradual lowering of capsNeither is currently in the policySuccess and Failures of Clean Water ActAnnual wetland loss decreased 80% since 1992Swimmable US streams increased from 36 to 60%US population served by sewage treatment increased from 32 to 74%Number of American getting good water increased from 79 to 94%40% of streams still too polluted for fishingTens of thousands of gas tanks are leakingEnvironmentalist want more preventive policiesVery costly to keep testing amounts of water pollutionSewage Treatment Reduces Water Pollution25% of US homes use septic tanksHome wastewater is pumped into the tankSoil and bacteria are used to treat the waterWhen the tank fills every few years, it must be pumped into a tank truckIf not maintained, they can cause sewage to back up and

Sewage treatment plantsSewer pipes bring wastewater to plantsPrimary sewage treatment: Physically removes suspended solids with screens/filtersSecondary: Biologically removes dissolved wastesTertiary: Uses specialized processes to remove specific pollutants. Very costlyChlorination: removes disease before dischargingStorm waters can overflow sewer systems and cause sewage dischargeBetter to have separate pipe networksWe Can Improve Conventional Sewage TreatmentComposting Toilet SystemsConvert human feces into fertilizer supplementCheap, saves water, and saves energy

Wetland Based Sewage TreatmentSeries of tanks to purify waterAlgae decompose organic wastePlants take up resulting nutrientsPasses through marsh to filter out more organic wasteSome plants can remove toxins and kill pathogensFlows into aquarium where microorganisms eaten by snails, which are eaten by larger fishFish can be sold as bait or foodWater goes into second marsh for more cleansingWater can be treated drinkable using UV lightWater is then dischargedCosts as much as conventional sewage plant