Environmental Problems, Their Causes, and Sustainability 1

EPA advised women who may become pregnant, pregnantwomen, and nursing mothers not to eat shark,swordfish, king mackerel, or tilefish and to limit theirconsumption of albacore tuna to no more than 170grams (6 ounces) per week. They also advised such individualsto check local advisories about the safety offish caught in local lakes, rivers, and coastal areas.Levels of methylmercury in lakes and lake organismsappear to be connected to acid deposition, becausethe conversion rate of inorganic mercury tomethylmercury is higher in acidified lakes.According to a 2001 study by the Centers forDisease Control and Prevention, 8% of Americanwomen of childbearing age risk having a baby bornwith irreversible neurological problems because of exposureof the fetus to mercury, mostly from the mothereating seafood contaminated with methylmercury.Problems include brain and nerve system damage thatcan result in cerebral palsy, delayed onset of walkingand talking, learning disabilities, tremors, irritability,impaired coordination, and memory loss. In theUnited States, up to 300,000 babies born each year areat risk from such problems due to mercury exposurewhile in the womb.Figure 24-27 lists ways to prevent or control humanexposure to mercury. In its 2003 report on global mercurypollution, the UN EnvironmentProgramme recommendedphasing out coalburning and waste incinerationas rapidly as possible.PreventionPhase out wasteincinerationRemove mercury fromcoal before it is burnedConvert coal to liquidor gaseous fuelSwitch from coal tonatural gas andrenewable energyresources suchas wind, solar cells,and hydrogenPhase out use ofmercury in all productsunless they are recycledIn 2003, environmentalengineers David Mazyck andChang Yu Wu at the Universityof Florida developed away to remove much of themercury from smokestackemissions. They inject tinyparticles of silica and a chemicalthat, when exposed to UVlight, produces highly reactivemolecules that removemost of the mercury insmokestack gases. The mercurycan be removed from thesilica so that the silica can bereused. And the mercury canbe sold for use in productssuch as fluorescent bulbs. Theresearchers have founded acompany, Sol-gel PowerTechnologies, to develop thetechnology.In 2000, the U.S. EPA officiallydetermined that mercuryis a hazardous substanceas defined by the Clean Air Act, which requiresthat emissions of such substances be strictly controlled.However, in 2003 the Bush administration opposedinternational limits on mercury emissions andother mandatory measures aimed at reducing the riskof mercury exposure, mostly from burning coal and incineratinghazardous wastes. Also, government analysisshows that President Bush’s proposed Clear Skiesair pollution control program will reduce mercury pollutionless than current regulations under the CleanAir Act and could allow emissions of mercury to tripleby 2013. In 2003, by executive order President Bush exemptedthe country’s more polluting coal-burningpower plants from having to follow a rule in the CleanAir Act that would require them to upgrade their airpollution control equipment whenever they do a significantexpansion (p. 456). This will further delay reducingmercury emissions by exempting the plantswith the highest mercury emissions from the requirementsof the Clean Air Act and result in hot spots nearsuch plants with high mercury levels.xHOW WOULD YOU VOTE? Should coal-burning electricityand industrial plants be required to sharply reduce mercuryemissions? Cast your vote online at http://biology.brookscole.com/miller14.SolutionsMercury PollutionControlSharply reduce mercuryemissions from coalburningplants andincineratorsTax each unit of mercuryemitted by coal-burningplants and incineratorsCollect and recyclemercury-containingelectric switches, relays,and dry-cell batteriesRequire labels on allproducts containingmercuryFigure 24-27 Solutions: ways to prevent or control inputs of mercury into the environment fromhuman activities—mostly through coal-burning plants and incinerators. Which two of these solutionsdo you believe are the most important?http://biology.brookscole.com/miller14557