3Math ProblemIf an average refrigerator uses 500 watts of energy per hour on a daily basis, and your energy cost is $0.11 per kwh, approximately how much does the energy used by the refrigerator cost per month?a. $1.30b. $13c. $40d. $55e. $132
6WATER POLLUTION: SOURCES, TYPES, AND EFFECTS Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses.Point source: specific location (drain pipes, ditches, sewer lines).Nonpoint source: cannot be traced to a single site of discharge (atmospheric deposition, agricultural / industrial / residential runoff)
9Major Water Pollutants and Their Effects Natural capital degradation: water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20°C (68°F). Only a few fish species can survive in water with less than 4 ppm of dissolved oxygen at this temperature.Water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20°C.Only a few fish species can survive in water less than 4ppm at 20°C.
10POLLUTION OF FRESHWATER STREAMS Most developed countries have sharply reduced point- source pollution but toxic chemicals and pollution from nonpoint sources are still a problem.Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.
11Cultural Eutrophication Eutrophication: the natural nutrient enrichment of a shallow lake, estuary or slow moving stream, mostly from runoff of plant nutrients from the surrounding land.Cultural eutrophication: human activities accelerate the input of plant nutrients (mostly nitrate- and phosphate-containing effluents) to a lake.85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication.
12Unconfined freshwater aquifer Confined aquifer Polluted airPesticidesand fertilizersHazardouswasteinjectionwellDeicingroad saltCoal stripmine runoffBuried gasolineand solvent tanksPumpingwellGasoline stationCesspool,septic tankWaterpumping wellWaste lagoonSewerLandfillLeakagefromfaultycasingAccidentalspillsFigure 21.7Natural capital degradation: principal sources of groundwater contamination in the United States. Another source is saltwater intrusion from excessive groundwater withdrawal (Figure 14-12, p. 315) (Figure is not drawn to scale.)DischargeUnconfined freshwater aquiferConfinedaquiferConfined freshwater aquiferGroundwaterflow
13POLLUTION OF GROUNDWATER It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of degradable wastes.Nondegradable wastes (toxic lead, arsenic, flouride) are there permanently.Slowly degradable wastes (such as DDT) are there for decades.
14Contaminant plume moves with the groundwater LeakingtankAquiferWatertableBedrockFigure 21.8Natural capital degradation: groundwater contamination from a leaking gasoline tank. As the contaminated water spreads from its source in a widening plume, it can be extracted by wells used to provide water for drinking and irrigation.GroundwaterflowFree gasolinedissolves ingroundwater(dissolvedphase)Gasolineleakage plume(liquid phase)Migratingvapor phaseWater wellContaminant plume moveswith the groundwater
15Groundwater Pollution SolutionsGroundwater PollutionPreventionCleanupFind substitutes for toxic chemicalsPump to surface, clean, and returnto aquifer (very expensive)Keep toxic chemicals out of the environmentInject microorganismsto clean up contamination (less expensive but still costly)Install monitoring wells near landfills and underground tanksRequire leak detectors on underground tanksFigure 21.9Solutions: methods for preventing and cleaning up contamination of groundwater. QUESTION: Which two of these solutions do you think are the most important?Pumpnanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed)Ban hazardous waste disposalin landfills and injection wellsStore harmful liquids in aboveground tanks with leak detection and collection systems
16and heavy metals in effluents flow into bays and estuaries. Cities IndustryNitrogen oxidesfrom autos andsmokestacks,toxic chemicals,and heavy metals in effluents flow into bays and estuaries.CitiesToxic metals and oil from streets and parking lots pollute waters;Urban sprawlBacteria and viruses fromsewers and septic tanks contaminate shellfish bedsConstruction sitesSediments are washed intowaterways, choking fish and plants, clouding waters, and blocking sunlight.FarmsRunoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.Red tidesExcess nitrogen causesexplosive growth oftoxicmicroscopic algae,poisoning fish andmarine mammals.Closedshellfish bedsClosedbeachOxygen-depletedzoneFigure 21.10Natural capital degradation: residential areas, factories, and farms all contribute to the pollution of coastal waters and bays. According to the UN Environment Programme, coastal water pollution costs the world $16 billion annually—$731,000 a minute—due to ill health and premature death.Toxic sedimentsChemicals and toxic metals contaminate shellfish beds, kill spawning fish, andaccumulate in the tissues of bottom feeders.Oxygen-depleted zoneSedimentation and algaeovergrowth reduce sunlight,kill beneficial sea grasses, useup oxygen, and degrade habitat.Healthy zoneClear, oxygen-richwaters promote growthof plankton and sea grasses,and support fish.Fig , p. 505
17OCEAN POLLUTIONHarmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff.
18Coastal Water Pollution SolutionsCoastal Water PollutionPreventionCleanupReduce input of toxic pollutantsImprove oil-spill cleanupcapabilitiesSeparate sewage and storm linesBan dumping of wastes and sewage by maritime and cruise ships in coastal watersSprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage withoutcreating harmful by-products(still under development)Ban ocean dumping of sludge and hazardous dredged materialProtect sensitive areas from development, oil drilling, andoil shippingFigure 21.14Solutions: methods for preventing and cleaning up excessive pollution of coastal waters. QUESTION: Which two of these solutions do you think are the most important?Require at least secondarytreatment of coastal sewageRegulate coastal developmentUse wetlands, solar-aquatic,or other methods to treat sewageRecycle used oilRequire double hulls for oil tankers
19Reducing Water Pollution through Sewage Treatment Raw sewage reaching a municipal sewage treatment plant typically undergoes:Primary sewage treatment: a physical process that uses screens and a grit tank to remove large floating objects and allows settling.Secondary sewage treatment: a biological process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable, oxygen demanding organic wastes.
20Reducing Water Pollution through Sewage Treatment Primary and Secondary sewage treatment.
21• Prevent groundwater contamination SolutionsWater Pollution• Prevent groundwater contamination• Reduce nonpoint runoff• Reuse treated wastewater for irrigation• Find substitutes for toxic pollutants• Work with nature to treat sewage• Practice four R's of resource use (refuse,reduce, recycle, reuse)Figure 21.18Solutions: methods for preventing and reducing water pollution. QUESTION: Which two of these solutions do you think are the most important?• Reduce air pollution• Reduce poverty• Reduce birth rates
22Environmental Organizations and Industries agencies-and-organizations/