HUMAN IMPACTS ON AQUATIC BIODIVERSITY Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Figure 12-2
Population Growth and Pollution Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Figure 12-3
Core Case Study: Using Nature to Purify Sewage Ecological wastewater purification by a living machine. – Uses the sun and a series of tanks containing plants, snails, zooplankton, crayfish, and fish (that can be eaten or sold for bait). Figure 21-1
Definition Excessive amounts of suspended soil particles that eventually settle out and accumulate on the bottom of a body of water. Sediment Pollution
Causes Erosion of agricultural lands, forest soils exposed by logging, degraded stream banks, overgrazed rangelands, strip mines, and construction.
Environmental Effects Reduces light penetration, covering aquatic organisms, bringing insoluble toxic pollutants into the water, and filling in waterways.
Health Effects Sediments adversely affect water quality by carrying toxic chemicals. The sediment particles provide surface area to which some insoluble, toxic compounds adhere; when the sediments enter the water, so do toxic chemicals. Disease-causing agents can also be transported into water via sediments.
Causes Release of waste water from drains or sewers (toilets, washing machines, and showers) and include human wastes, soaps and detergents.
Environmental Effects Enrichment – the fertilization of a body of water, caused by the presence of high levels of plants and algal nutrients like nitrogen and phosphorus
Health Effects Oxygen – dissolved oxygen is needed by organisms, like fish, but when sewage enters an aquatic ecosystem, the micro-organisms bloom, leaving less oxygen for the fish, etc., and then they die Sewage carries disease-causing agents.
Definition Infectious organisms that cause disease. Disease-Causing Agents
Environmental Effects Municipal wastewater contains bacteria, viruses, protozoa, parasitic worms, and other infectious agents that cause human or animal diseases.Causes Comes from the wastes of infected individuals. Comes from the wastes of infected individuals.
Health Effects Typhoid, cholera, bacterial dysentery, polio and infectious hepatitis are some of the more common bacteria or viruses that are transmitted through contaminated food and water.
Major Water Pollutants and Their Effects 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. Figure 21-3
Chemicals such as nitrogen and phosphorus that stimulate the growth of plants and algae. Read “The Dead Zone” Raven, page 517. Inorganic Plant and Algal Nutrients
Causes Nitrates and phosphates come from sources such as human and animal wastes, plant residues, atmospheric deposition and residential land.
Environmental Effects Inorganic plant and algal nutrients encourage excessive growth of algal and aquatic plants. This causes problems, including enrichment and bad odor.
Causes Chemicals that contain carbon atoms. Most of the thousands of organic compounds found in water are synthetic chemicals that are produced by human activities; these included pesticides, solvents, industrial chemicals and plastics, and seepage from landfills. Organic Compounds
Health Effects Hundreds of synthetic organic compounds are toxic and some of these have been shown to cause cancer or birth defects. Pollutes streams and groundwater. Pollutes streams and groundwater. Environmental Effects
Causes Chemicals are contaminants that contain elements other than carbon. Examples include acids, salts, and heavy metals. Many inorganic chemicals find their way into both surface water and groundwater from sources such as industries, mines, irrigation runoff, oil drilling and urban runoff from storm sewers.
Environmental Effects Some of these inorganic pollutants are toxic to aquatic organisms.
Health Effects Lead and mercury are poisonous. Mercury exposure to developing fetuses in pregnant women has been linked to a variety of conditions such as mental retardations, cerebral palsy, and developing delays, causes kidney disorders and several damage the nervous and cardiovascular systems. Low levels of mercury in the brain cause neurological problems such as headache, depression, and quarrelsome behavior. Low levels of mercury in the brain cause neurological problems such as headache, depression, and quarrelsome behavior.
Radioactive Substances Contains atoms of unstable isotopes that spontaneously emit radiation
Causes Radioactive substances get into water from several sources like the mining and processing of radioactive minerals such as uranium and thorium. The nuclear weapons industry use the largest amounts. Medical and scientific research facilities also use them.
Health Effects Mutations, birth defects, mental retardation, genetic disease, leukemia, cancer (breast, bone, thyroid, skin, lung), burns, cataracts, male sterility. Pollutes air, water and soil. Environmental Effects
Causes When heated water produced during certain industrial processes is released into waterways. Thermal Pollution
Environmental Effects Decomposition of wastes occurs faster, depleting the water of oxygen; this affects aquatic life. Typically affects animals, not humans. Health Effects
WATER 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)
Point Source Pollution Water pollution that can be traced to a specific spot (such as a factory or sewage treatment plant) because it is discharged into the environment through pipes, sewers or ditches.
Non-Point Source Pollution Pollutants that enter bodies of water over large areas rather than being concentrated at a single point of entry. Ex. Agricultural fertilizer runoff and sediments from construction.
Agriculture Fertilizers, animal wastes, etc. Sources of Pollution Sewage, fertilizers, dumping into drainage ditches, etc. Sewage, fertilizers, dumping into drainage ditches, etc. Municipal Waste Industrial Waste Chemicals left over from manufacturing, waste products, etc. Chemicals left over from manufacturing, waste products, etc.
Cultural 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.
Definition The enrichment of a lake or pond by inorganic plant and algal nutrients such as phosphorus.Eutrophication Because this gets into our water supply from runoff, etc., and is something that is not normally in the water, it is considered pollution. Because this gets into our water supply from runoff, etc., and is something that is not normally in the water, it is considered pollution. Relation to Pollution
Cause/Effect Fertilizers, erosion, sewage, etc. get into water and the effect is high photosynthetic productivity. Thus, the water is cloudy and usually resembles pea soup because of the algae and cyanobacteria that are supported by the nutrients.
POLLUTION OF FRESHWATER STREAMS Flowing streams can recover from a moderate level of degradable water pollutants if they are not overloaded and their flows are not reduced. – In a flowing stream, the breakdown of degradable wastes by bacteria depletes DO and creates and oxygen sag curve. This reduces or eliminates populations of organisms with high oxygen requirements.
Water Pollution Problems in Streams Dilution and decay of degradable, oxygen- demanding wastes and heat in a stream. Figure 21-4
POLLUTION 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.
Global Outlook: Stream Pollution in Developing Countries Water in many of central China's rivers are greenish black from uncontrolled pollution by thousands of factories. Figure 21-5
Case Study: India’s Ganges River: Religion, Poverty, and Health Religious beliefs, cultural traditions, poverty, and a large population interact to cause severe pollution of the Ganges River in India. – Very little of the sewage is treated. – Hindu believe in cremating the dead to free the soul and throwing the ashes in the holy Ganges. Some are too poor to afford the wood to fully cremate. Decomposing bodies promote disease and depletes DO.
Case Study: India’s Ganges River: Religion, Poverty, and Health Daily, more than 1 million Hindus in India bathe, drink from, or carry out religious ceremonies in the highly polluted Ganges River. Figure 21-6
POLLUTION OF FRESHWATER LAKES Dilution of pollutants in lakes is less effective than in most streams because most lake water is not mixed well and has little flow. – Lakes and reservoirs are often stratified and undergo little mixing. – Low flow makes them susceptible to runoff. Various human activities can overload lakes with plant nutrients, which decrease DO and kill some aquatic species.
Coral Reef Risks Of the 109 countries with large reefs, 90 are damaging them, and 27% of the coral reefs are at high risk, especially off the coast of Southeastern Asia. In the western Atlantic, 30-50% of all coral species are either rare or endangered.
Coral Reef Risks Con’t Silt washing from downstream has smothered the reefs High salinity from fresh water diversion, over- fishing, boat groundings, fishing with dynamite or cyanide, hurricane damage, disease, coral bleaching, land reclamation, tourism, and the mining of coral for building materials.
Protection of 300 coral reefs in 65 countries are protected as reserves or parks, and another 600 have been recommended for protection. The good news is coral reefs can often recover from damage.
Differences of Opinion Oceans dilute, disperse, and degrade large amounts of raw sewage, sewage sludge, oil, and some types of industrial waste, especially in deep-water areas. Marine life has proved to be more resilient than some scientists expected, some suggest it is safer to dump sludge & other hazardous wastes into the deep ocean than to bury them on land or burn them.
Differences of Opinion Other scientists disagree, pointing out that we know less about the deep ocean than we do about space. They say that dumping waste in the ocean would delay urgently needed pollution prevention and promote further degradation of this vital part of the earth’s life-support system.
Oil Spills When a tanker accident happens, it gets lots of publicity. But, more oil is released by normal operation of offshore wells, washing tankers & from pipeline or storage tank leaks. One estimate says that oil companies spill, leak, or waste per year an amount of oil equal to that shipped by 1000 huge Exxon Valdez tankers.
Floating Oil Oil coats the feathers of birds (especially diving birds) and the fur of marine animals, destroying the animals’ natural insulation and buoyancy Many drown or die of exposure from loss of body heat.
Other Information Oil is broken down by bacteria over time; slower in cold waters. Heavy oil components can smother bottom- dwelling organisms such as crabs, oysters, mussels, and clams, or make them unfit to eat. Oil spills have killed coral reefs. A recent study showed that diesel oil becomes more toxic to marine life with the passage of time.
Mechanical Methods Floating booms contain the oil spill or keep it from reaching sensitive areas Skimmer boats are used to vacuum up some of the oil into collection barges Absorbent pads or large feather-filled pillows are used to soak up oil on beaches or in waters that are too shallow for skimmer boats
Chemical Methods Coagulating agents cause floating oil to clump together for easier pickup or sink to the bottom, where it usually does less harm. Dispersing agents break up oil slicks. However, these can also damage some types of organisms. Fire can also burn off floating oil, but crude oil is hard to ignite.
Reducing Water Pollution through Sewage Treatment Septic tanks and various levels of sewage treatment can reduce point-source water pollution. Figure 21-15
Reducing Water Pollution through Sewage Treatment Primary and Secondary sewage treatment. Figure 21-16
Reducing Water Pollution through Sewage Treatment Advanced or tertiary sewage treatment: – Uses series of chemical and physical processes to remove specific pollutants left (especially nitrates and phosphates). Water is chlorinated to remove coloration and to kill disease-carrying bacteria and some viruses (disinfect).
Reducing 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.
Primary Removes suspended and floating particles, such as sand and silt, by mechanical processes such as screening and gravitational settling. The solid material that is settled out is called primary sludge. Bar screens, grit chambers, primary clarifiers, digesters and pre-aeration
Secondary Uses microorganisms to decompose the suspended organic material in wastewater. Ex. trickling filters – where wastewater trickles through aerated rock beds that contain bacteria and other microorganisms, which degrade the organic material in the water.
Secondary (Cont.) Or activated sludge process – wastewater is aerated and circulated through bacteria-rich particles; the bacteria degrade suspended organic material. After several hours, the particles and microorganisms are allowed to settle out, forming secondary sludge. Use aeration basins, settling tanks and sand filters
Tertiary This includes a variety of biological, chemical and physical processes used to remove phosphorus and nitrogen, the nutrients most commonly associated with enrichment. Tertiary treatment can also be used to purify wastewater so that it can be reused in communities where water is scarce. Use chlorine as a disinfection and then chlorine is removed by SO2 so it can be released into river.
Reducing Water Pollution through Sewage Treatment Sewage sludge can be used as a soil conditioner but this can cause health problems if it contains infectious bacteria and toxic chemicals. Preventing toxic chemicals from reaching sewage treatment plants would eliminate such chemicals from the sludge and water discharged from such plants.
Reducing Water Pollution through Sewage Treatment Natural and artificial wetlands and other ecological systems can be used to treat sewage. – California created a 65 hectare wetland near Humboldt Bay that acts as a natural wastewater treatment plant for the town of 16,000 people. The project cost less than half of the estimated price of a conventional treatment plant.
United States Groundwater contamination still occurs, especially due to non-point source pollution, but laws like the Safe Drinking Water Act, Clean Water Act, and Water Quality Act have helped in the U.S. Water Quality
Global Problems According to the World Health Organization, an estimated 1.4 billion people still do not have access to adequate sanitation systems. Worldwide, at least 250 million cases of water-related illnesses occur each year, with 5 million or more of these resulting in death.
Dissolved Oxygen The amount of oxygen gas dissolved in a given volume of water at a particular temperature and pressure. Specific Water Quality Measures
Carbon Dioxide Enters aquatic systems from the atmosphere and from respiration by animals. The concentration of CO2 varies at different depths because of light/photosynthesis.
Nitrate Contaminates shallow groundwater (100 feet or less) and usually comes from fertilizers. It’s a concern in rural areas where 80-90% of the residents use shallow groundwater for drinking. This harms humans because it reduces the blood’s ability to transport oxygen.
Sulfate Problem because too much can kill fish. Gets in water from industrial processes and mining.
Iron Causes problems because it separates out of the water and forms particulates (sediment), it tastes bad if it gets in our water, and can coat fish’s gills. Groundwater problems in wells, from natural minerals in rocks.
Phosphate Plant nutrients that cause algae blooms. It comes from detergents, human wastes and fertilizers.
Coliform General group of bacteria from animal wastes. It uses up available oxygen. Also causes e-coli disease.
Giardia Organism (protozoa) that can cause diarrhea if you drink unchlorinated water. It is a natural organism that lives in the guts of animals.
Chloride Part of salts, but too many can cause too much salt in the water. Too much is bad; a little is okay. It is naturally found in water, but can come from pollution.
pH Too high/too low can be bad; fish like 6.5-9.5; acid mine drainage can kill fish.
Hardness Calcium and magnesium dissolved in the water. A little is good (50-400 ppm for fish is good), but very low or high is a problem. Low is more of a problem. Affects fish eggs, poor bone development.
Turbidity Cloudiness/muddiness; blocks the light; coats fish gills.
Definition Calcium and magnesium in the water. Can cause problems with cleaning clothes. Soap doesn’t bubble as much. Hard Water
Ion Exchange Substitute sodium for calcium and magnesium. Water softeners usually do this. Methods of Treating
Reverse Osmosis Membrane system that allows water to go through but calcium and magnesium cannot.
POLLUTION OF GROUNDWATER Leaks from a number of sources have contaminated groundwater in parts of the world. – According the the EPA, one or more organic chemicals contaminate about 45% of municipal groundwater supplies. – By 2003, the EPA had completed the cleanup of 297,000 of 436,000 underground tanks leaking gasoline, diesel fuel, home heating oil, or toxic solvents.
Case Study: Arsenic in Groundwater - a Natural Threat Toxic Arsenic (As) can naturally occur at high levels in soil and rocks. Drilling into aquifers can release As into drinking water supplies. According to WHO, more than 112 million people are drinking water with As levels 5-100 times the 10 ppb standard. – Mostly in Bangladesh, China, and West Bengal, India.
Safe Drinking Water Act It required the EPA to determine the maximum contaminant level, the max permissible amount of any pollutant that might adversely affect human health. Water Legislation
PREVENTING AND REDUCING SURFACE WATER POLLUTION Most developed countries use laws to set water pollution standards, but such laws rarely exist in developing countries. – The U.S. Clean Water Act sets standards fro allowed levels of key water pollutants and requires polluters to get permits. – EPA is experimenting with a discharge trading policy similar to that for air pollution control.
Clean Water Act Has two basic goals: – To eliminate the discharge of pollutants in U.S. waterways To attain water quality levels that make these waterways safe to fish and swim in.
Water Quality Act controlling toxic pollutant discharges control non-point sources of pollution authorized $18 billion for wastewater treatment address problems such as coastal estuaries, the Great Lakes, and the Chesapeake Bay
Using Laws to Protect Drinking Water The U.N. estimates that 5.6 million Americans drink water that does not meet EPA standards. 1 in 5 Americans drinks water from a treatment plant that violated one or more safety standard. Industry pressures to weaken the Safe Drinking Act: – Eliminate national tests and public notification of violations. – Allow rights to pollute if provider cannot afford to comply.
Is Bottled Water the Answer? Some bottled water is not as pure as tap water and costs much more. – 1.4 million metric tons of plastic bottles are thrown away. – Fossil fuels are used to make plastic bottles. The oil used to produce plastic bottles in the U.S. each year would fuel 100,000 cars.
Bioaccumulation Increase in the concentration of a chemical in specific organs or tissues at a level higher than normal. Stored in body fat and can be passed along to offspring. Usually a concern to organisms higher on the food chain.
Food/Water Contamination Pesticides run off into our water as we spray for bugs & stay on our food.
Pesticide Poisoning Short-term exposure to high levels of pesticides can result in harm to organs and even death Long-term exposure to lower levels of pesticides can cause cancer. Children are at a greater risk than adults.
Symptoms Nausea, vomiting, and headaches. More serious can result in damage to the nervous system & other body organs. Pesticide Poisoning The W.H.O. estimates that more than 3 million people are poisoned by pesticides each year, & about 220,000 die. Examples
National Cancer Institute Pesticides have been shown to cause lymphomas, leukemia, brain, lung, and testicular cancers. The issue of whether certain pesticides cause breast cancer remains unresolved Researchers have noted a correlation between a high level of pesticides in the breast's fatty tissue and cancer.
EPA The EPA & USDA are responsible for the overseeing the laws. Pesticides and the Law
Research Pesticide companies must use 3 methods to determine pesticides health threats: – Case Reports – (made to physicians) about people suffering from adverse health effects – Laboratory Investigations – (usually on animals) to determine toxicity, residence time, what parts of the body are affected and how the harm takes place. – Epidemiology – (in populations of humans exposed) used to find why some people get sick while others do not
Days to Harvest The last day you can spray crops before you harvest them for human consumption.
Restrictions The EPA sets a tolerance level specifying the amount of toxic pesticide residue that can legally remain on the crop when the consumer eats it.
FFDCA Federal Food, Drug, and Cosmetic Act Strengthened in 1996 Sets pesticide tolerance levels
Label Requirements – the brand name – the ingredient statement – the percentage or amount of active ingredient(s) by weight – the net contents of the container – the name and address of the manufacturer – Registration and establishment numbers – Signal words and symbols – Precautionary statement – Statement of practical treatment – Environmental hazard statement – Classification statement – Directions for use – Re-entry statement – Harvesting and/or grazing restrictions – Storage and disposal statement.
FIFRA The Federal Insecticide, Fungicide & Rodenticide Act It was first established in 1947 & revised as recently as 1996. States what must be on a pesticide label & requires registration of all pesticides.
FQPA Food Quality Protection Act Established in 1996 Amends both FIFRA and FFDCA.
Time Rachel Carson lived from 1907 to 1964. She published her famous work Silent Spring in 1962. Rachel Carson
Contributions “Pesticide sprays, dusts, and aerosols are now applied almost universally to farms, gardens, forests, and homes - non selective chemicals that have the power to kill every insect, the good and the bad, to still the song of birds and the leaping of fish in the streams, to coat the leaves with a deadly film and to linger on soil - all this though the intended target may be only a few weeds or insects. Can anyone believe...
Contributions... it is possible to lay down such a barrage of poisons on the surface of the earth without making it unfit for life? They should not be called insecticides, but biocides.” Silent Spring heightened public awareness and concern about the dangers of uncontrolled use of DDT and other pesticides, including poisoning wildlife and contaminating human food supplies.
RISKS AND HAZARDS Risk is a measure of the likelihood that you will suffer harm from a hazard. We can suffer from: – Biological hazards: from more than 1,400 pathogens. – Chemical hazards: in air, water, soil, and food. – Physical hazards: such as fire, earthquake, volcanic eruption… – Cultural hazards: such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.
BIOLOGICAL HAZARDS: DISEASE IN DEVELOPED AND DEVELOPING COUNTRIES Diseases not caused by living organisms cannot spread from one person to another (nontransmissible disease), while those caused by living organisms such as bacteria and viruses can spread from person to person (transmissible or infectious)
Transmissible Disease Pathway for infectious disease in humans. Figure 18-4
Transmissible Disease WHO estimates that each year the world’s seven deadliest infections kill 13.6 million people – most of them the poor in developing countries. Figure 18-5
Case Study: The Growing Global Threat from Tuberculosis The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people 2020. Recent increases in TB are due to: – Lack of TB screening and control programs especially in developing countries due to expenses. – Genetic resistance to the most effective antibiotics.
Viral Diseases Flu, HIV, and hepatitis B viruses infect and kill many more people each year then highly publicized West Nile and SARS viruses. – The influenza virus is the biggest killer virus worldwide. Pigs, chickens, ducks, and geese are the major reservoirs of flu. As they move from one species to another, they can mutate and exchange genetic material with other viruses.
Viral Diseases HIV is the second biggest killer virus worldwide. Five major priorities to slow the spread of the disease are: – Quickly reduce the number of new infections to prevent further spread. – Concentrate on groups in a society that are likely to spread the disease. – Provide free HIV testing and pressure people to get tested. – Implement educational programs. – Provide free or low-cost drugs to slow disease progress.
Case Study: Malaria – Death by Mosquito Malaria kills about 2 million people per year and has probably killed more than all of the wars ever fought. Figure 18-7
Spraying insides of homes with low concentrations of the pesticide DDT greatly reduces the number of malaria cases. – Under international treaty enacted in 2002, DDT is being phased out in developing countries. Case Study: Malaria – Death by Mosquito
Ecological Medicine and Infectious Diseases Mostly because of human activities, infectious diseases are moving at increasing rates from one animal species to another (including humans). Ecological (or conservation) medicine is devoted to tracking down these connections between wildlife and humans to determine ways to slow and prevent disease spread.
CHEMICAL HAZARDS A toxic chemical can cause temporary or permanent harm or death. – Mutagens are chemicals or forms of radiation that cause or increase the frequency of mutations in DNA. – Teratogens are chemicals that cause harm or birth defects to a fetus or embryo. – Carcinogens are chemicals or types of radiation that can cause or promote cancer.
CHEMICAL HAZARDS A hazardous chemical can harm humans or other animals because it: – Is flammable – Is explosive – An irritant – Interferes with oxygen uptake – Induce allergic reactions.
Effects of Chemicals on the Immune, Nervous, and Endocrine Systems Long-term exposure to some chemicals at low doses may disrupt the body’s: – Immune system: specialized cells and tissues that protect the body against disease and harmful substances. – Nervous system: brain, spinal cord, and peripheral nerves. – Endocrine system: complex network of glands that release minute amounts of hormones into the bloodstream.
Case Study: A Black Day in Bhopal, India The world’s worst industrial accident occurred in 1984 at a pesticide plant in Bhopal, India. – An explosion at Union Carbide pesticide plant in an underground storage tank released a large quantity of highly toxic methyl isocyanate (MIC) gas. – 15,000-22,000 people died – Indian officials claim that simple upgrades could have prevented the tragedy.
TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Factors determining the harm caused by exposure to a chemical include: – The amount of exposure (dose). – The frequency of exposure. – The person who is exposed. – The effectiveness of the body’s detoxification systems. – One’s genetic makeup.
TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Children are more susceptible to the effects of toxic substances because: – Children breathe more air, drink more water, and eat more food per unit of body weight than adults. – They are exposed to toxins when they put their fingers or other objects in their mouths. – Children usually have less well-developed immune systems and detoxification processes than adults.
RISK ANALYSIS Annual deaths in the U.S. from tobacco use and other causes in 2003. Figure 18-A
RISK ANALYSIS Number of deaths per year in the world from various causes. Parentheses show deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors. Figure 18-13
Fig. 18-13, p. 435 Cause of deathAnnual deaths Poverty/malnutrition/ disease cycle 11 million (75) Tobacco 5 million (34) Pneumonia and flu 3.2 million (22) Air pollution 3 million (21) HIV/AIDS Malaria 2 million (14) Diarrhea 1.9 million (13) Tuberculosis 1.7 million (12) Car accidents 1.2 million (8) Work-related injury & disease 1.1 million (8) Hepatitis B 1 million (7) Measles 800,000 (5) 3 million (21)
Perceiving Risk Most individuals evaluate the relative risk they face based on: – Degree of control. – Fear of unknown. – Whether we voluntarily take the risk. – Whether risk is catastrophic. – Unfair distribution of risk. Sometimes misleading information, denial, and irrational fears can cloud judgment.
RISK ANALYSIS Comparisons of risks people face expressed in terms of shorter average life span. Figure 18-14
AIR POLLUTION Some primary air pollutants may react with one another or with other chemicals in the air to form secondary air pollutants. Figure 19-3
Major Air Pollutants Carbon oxides: – Carbon monoxide (CO) is a highly toxic gas that forms during the incomplete combustion of carbon- containing materials. – 93% of carbon dioxide (CO 2 ) in the troposphere occurs as a result of the carbon cycle. – 7% of CO 2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels). It is not regulated as a pollutant under the U.S. Clean Air Act.
Major Air Pollutants Nitrogen oxides and nitric acid: – Nitrogen oxide (NO) forms when nitrogen and oxygen gas in air react at the high-combustion temperatures in automobile engines and coal- burning plants. NO can also form from lightening and certain soil bacteria. NO reacts with air to form NO 2. NO 2 reacts with water vapor in the air to form nitric acid (HNO 3 ) and nitrate salts (NO 3 - ) which are components of acid deposition.
Major Air Pollutants Sulfur dioxide (SO 2 ) and sulfuric acid: – About one-third of SO 2 in the troposphere occurs naturally through the sulfur cycle. – Two-thirds come from human sources, mostly combustion (S+ O 2 SO 2 ) of sulfur-containing coal and from oil refining and smelting of sulfide ores. – SO 2 in the atmosphere can be converted to sulfuric acid (H 2 SO 4 ) and sulfate salts (SO 4 2- ) that return to earth as a component of acid deposition.
Major Air Pollutants Suspended particulate matter (SPM): – Consists of a variety of solid particles and liquid droplets small and light enough to remain suspended in the air. – The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5). – According to the EPA, SPM is responsible for about 60,000 premature deaths a year in the U.S.
Major Air Pollutants Ozone (O 3 ): – Is a highly reactive gas that is a major component of photochemical smog. – It can Cause and aggravate respiratory illness. Can aggravate heart disease. Damage plants, rubber in tires, fabrics, and paints.
Major Air Pollutants Volatile organic compounds (VOCs): – Most are hydorcarbons emitted by the leaves of many plants and methane. – About two thirds of global methane emissions comes from human sources. – Other VOCs include industrial solvents such as trichlorethylene (TCE), benzene, and vinyl chloride. Long-term exposure to benzene can cause cancer, blood disorders, and immune system damage.
Major Air Pollutants Radon (Rn): – Is a naturally occurring radioactive gas found in some types of soil and rock. – It can seep into homes and buildings sitting above such deposits.
Secondary Pollutants Form when primary pollutants react
URBAN OUTDOOR AIR POLLUTION Industrial smog is a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended solid particles emitted mostly by burning coal. – In most developed countries where coal and heavy oil is burned, industrial smog is not a problem due to reasonably good pollution control or with tall smokestacks that transfer the pollutant to rural areas.
Sunlight plus Cars Equals Photochemical Smog Photochemical smog is a mixture of air pollutants formed by the reaction of nitrogen oxides and volatile organic hydrocarbons under the influence of sunlight.
Sunlight plus Cars Equals Photochemical Smog Mexico City is one of the many cities in sunny, warm, dry climates with many motor vehicles that suffer from photochemical smog. Figure 19-4
Factors Influencing Levels of Outdoor Air Pollution Outdoor air pollution can be reduced by: – settling out, precipitation, sea spray, winds, and chemical reactions. Outdoor air pollution can be increased by: – urban buildings (slow wind dispersal of pollutants), mountains (promote temperature inversions), and high temperatures (promote photochemical reactions).
Temperature Inversions Cold, cloudy weather in a valley surrounded by mountains can trap air pollutants (left). Areas with sunny climate, light winds, mountains on three sides and an ocean on the other (right) are susceptible to inversions. Figure 19-5
ACID DEPOSITION Sulfur dioxides, nitrogen oxides, and particulates can react in the atmosphere to produce acidic chemicals that can travel long distances before returning to the earth’s surface. – Tall smokestacks reduce local air pollution but can increase regional air pollution.
ACID DEPOSITION Acid deposition consists of rain, snow, dust, or gas with a pH lower than 5.6. Figure 19-6
ACID DEPOSITION pH measurements in relation to major coal- burning and industrial plants. Figure 19-7
ACID DEPOSITION Acid deposition contributes to chronic respiratory disease and can leach toxic metals (such as lead and mercury) from soils and rocks into acidic lakes used as sources for drinking water.
ACID DEPOSITION Air pollution is one of several interacting stresses that can damage, weaken, or kill trees and pollute surface and groundwater. Figure 19-9
Fig. 19-10, p. 452 Solutions Acid Deposition PreventionCleanup Reduce air pollution by improving energy efficiency Add lime to neutralize acidified lakes Reduce coal use Add phosphate fertilizer to neutralize acidified lakes Increase natural gas use Increase use of renewable energy resources Burn low-sulfur coal Remove SO 2 particulates & NO x from smokestack gases Remove NO x from motor vehicular exhaust Tax emissions of SO 2
Air Quality is better in US; EPA estimates since 1970 Particulate Matter (PM)- down 78% Carbon Dioxide (CO2)- down 23% Nitrogen Dioxide (Nox)- up 14% Lead (Pb)- down 98% Sulfur Dioxide (SO2)- down 32% Air quality is worse in developing countries: Mexico City & Beijing: air exceeds WHO standards 350 days/year
INDOOR AIR POLLUTION Indoor air pollution usually is a greater threat to human health than outdoor air pollution. According to the EPA, the four most dangerous indoor air pollutants in developed countries are: – Tobacco smoke. – Formaldehyde. – Radioactive radon-222 gas. – Very small fine and ultrafine particles.
INDOOR AIR POLLUTION Household dust mites that feed on human skin and dust, live in materials such as bedding and furniture fabrics. – Can cause asthma attacks and allergic reactions in some people. Figure 19-12
Case Study: Radioactive Radon Radon-222, a radioactive gas found in some soils and rocks, can seep into some houses and increase the risk of lung cancer. Sources and paths of entry for indoor radon-222 gas Sources and paths of entry for indoor radon-222 gas. Figure 19-13
HEALTH EFFECTS OF AIR POLLUTION Normal human lungs (left) and the lungs of a person who died of emphysema (right). Figure 19-15
Air Pollution is a Big Killer Each year, air pollution prematurely kills about 3 million people, mostly from indoor air pollution in developing countries. – In the U.S., the EPA estimates that annual deaths related to indoor and outdoor air pollution range from 150,000 to 350,000. – According to the EPA, each year more than 125,000 Americans get cancer from breathing diesel fumes.
Air Pollution is a Big Killer Spatial distribution of premature deaths from air pollution in the United States. Figure 19-16
PREVENTING AND REDUCING AIR POLLUTION The Clean Air Acts in the United States have greatly reduced outdoor air pollution from six major pollutants: – Carbon monoxide – Nitrogen oxides – Sulfur dioxides – Suspended particulate matter (less than PM- 10)
Using the Marketplace to Reduce Outdoor Air Pollution To help reduce SO 2 emissions, the Clean Air Act authorized an emission trading (cap-and- trade) program. – Enables the 110 most polluting power plants to buy and sell SO 2 pollution rights. – Between 1990-2002, the emission trading system reduced emissions. – In 2002, the EPA reported the cap-and-trade system produced less emission reductions than were projected.
Solutions: Reducing Outdoor Air Pollution There are a of ways to prevent and control air pollution from coal-burning facilities. – Electrostatic precipitator: are used to attract negatively charged particles in a smokestack into a collector. – Wet scrubber: fine mists of water vapor trap particulates and convert them to a sludge that is collected and disposed of usually in a landfill.
Solutions: Reducing Outdoor Air Pollution There are a # of ways to prevent and control air pollution from motor vehicles. – Because of the Clean Air Act, a new car today in the U.S. emits 75% less pollution than did pre- 1970 cars. – There is and increase in motor vehicle use in developing countries and many have no pollution control devices and burn leaded gasoline.
Fig. 19-19, p. 460 Solutions Motor Vehicle Air Pollution PreventionCleanup Emission control devices Mass transit Bicycles and walking Less polluting engines Less polluting fuels Improve fuel efficiency Car exhaust inspections twice a year Get older, polluting cars off the road Give buyers large tax write-offs or rebates for buying low-polluting, energy efficient vehicles Stricter emission standards
Indoor Air Pollution Little effort has been devoted to reducing indoor air pollution even though it poses a much greater threat to human health than outdoor air pollution. Environmental and health scientists call for us to focus on preventing air pollution (especially indoor) in developing countries.
Fig. 19-20, p. 461 Solutions Indoor Air Pollution Prevention Cover ceiling tiles & lining of AC ducts to prevent release of mineral fibers Use adjustable fresh air vents for work spaces Increase intake of outside air Ban smoking or limit it to well ventilated areas Change air more frequently Set stricter formaldehyde emissions standards for carpet, furniture, and building materials Circulate a building’s air through rooftop green houses Prevent radon infiltration Use exhaust hoods for stoves and appliances burning natural gas Use office machines in well ventilated areas Use less polluting substitutes for harmful cleaning agents, paints, and other products Install efficient chimneys for wood-burning stoves Cleanup or Dilution