WATER POLLUTION. Adapted from MBHS

Transcription

1 WATER POLLUTION Adapted from MBHS

2 Freshwater pollution Water for human consumption and other organisms needs to be: Disease-free Nontoxic Half of the world s major rivers are seriously depleted and polluted They poison surrounding ecosystems Threatening the health and livelihood of people The invisible pollution of groundwater has been called a covert crisis

3 Point and nonpoint sources of pollution Pollution = the release of matter or energy that causes undesirable impacts on the health and well-being of humans or other organisms Point sources = discrete locations of water pollution Factories, sewer pipes Addressed by the U.S. Clean Water Act Nonpoint sources = pollution arises from multiple inputs over larger areas (farms, city streets, neighborhoods) The major source of U.S. water pollution

4 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. Aka you can physically point to it s source.

5 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.

6 Freshwater pollution sources

7 Indicators of water quality Scientists measure properties of water to characterize its quality Biological indicators: presence of fecal coliform bacteria, disease-causing organisms, algae, etc. Chemical indicators: nutrient concentrations, ph, taste, odor, hardness, dissolved oxygen Physical indicators: color, temperature, turbidity Think back to our Eco-Columns!

8 Indicators DO- dissolved oxygen- The amount of oxygen gas dissolved in a given volume of water at a particular temperature and pressure. Nitrates- causes eutrophication- contaminates shallow groundwater and usually comes from fertilizers. Phosphate- causes eutrophication Plant nutrients that cause algae blooms. It comes from detergents, human wastes and fertilizers.

9 Indicators Hardness- Calcium and magnesium dissolved in the water. A little is good but very low (biggest problem) or too high is a problem. Affects fish eggs, poor bone development. ph- Too high/too low can be bad; fish like ; acid mine drainage can kill fish. Turbidity - Cloudiness/muddiness; blocks the light; coats fish gills.

10 Water Pollution from Agriculture Agriculture is leading source of water pollution in US Animal wastes and plants residues have high BOD Chemical pesticides can leach into groundwater Almost all streams and rivers are polluted with agricultural pesticides 72% of water pollution in rivers is from agriculture 2012 John Wiley & Sons, Inc. All rights reserved.

11 Municipal Water Pollution 2012 John Wiley & Sons, Inc. All rights reserved.

12 Major Water Pollutants and Their Sources Type/Effects Examples Major Sources Infectious agents Cause diseases Oxygen- demanding wastes Deplete dissolved O 2 needed by aquatic species Plant nutrients Cause excessive growth of algae and other species Organic Chemicals Add toxins to aquatic systems Inorganic chemicals Add toxins to aquatic systems Sediments Disrupt photosynthesis, food webs, other processes Thermal Make some species vulnerable to disease Bacteria, viruses, parasites Biodegradable animal wastes and plant debris Nitrates and phosphates Oil, gasoline, plastics, pesticides, cleaning solvents Acids, salts, metal compounds Soil, silt Heat Human and animal wastes Sewage, animal feedlots, food processing facilities Sewage, animal waste, inorganic fertilizers Industry, farms, households Industry, households, surface runoff Land erosion Electric power and industrial plants

13 Pathogens and waterborne diseases Enter water supplies through inadequately treated human waste and animal waste from feedlots Fecal coliform bacteria indicate fecal contamination They are not pathogenic organisms But the water may also hold other disease-causing pathogens (e.g., giardiasis, typhoid, hepatitis A) Bacterial pollution causes more human health problems than any other type of water pollution Conditions are improving 86% of people now have safe water

14 Infectious organisms that cause diseases Originate in the wastes of infected individuals Common bacterial or viral diseases: Typhoid, cholera, bacterial dysentery and infectious hepatitis

15 Disease-causing Agents Monitored by testing for presence of E. coli in the water via a fecal coliform test Indicates the presence of pathogenic organisms 2012 John Wiley & Sons, Inc. All rights reserved.

16 Pathogens cause human health problems 1 billion are still without safe water 2.6 billion have inadequate sewer or sanitary facilities - Mostly rural Asians and Africans Health impacts kill 5 million people per year Solutions: - Disinfect drinking water - Treat sewage - Public education to encourage personal hygiene - Government enforcement of regulations protecting food

17 Nutrient pollution Nutrient pollution from fertilizers, farms, sewage, lawns, golf courses leads to eutrophication Fertilizers add phosphorus to water, which boosts algal and aquatic plant growth Spreading algae cover the surface, decreasing sunlight Bacteria eat dead algae, reducing dissolved oxygen Fish and shellfish die Solutions include treating wastewater Reducing fertilizer application Using phosphate-free detergents Planting vegetation to increase nutrient uptake

18 Water Pollution Problems in Streams Dilution and decay of degradable, oxygen-demanding wastes and heat in a stream. Figure 21-4

19 Inorganic Plant and Algal Nutrient- The Dead Zone 2012 John Wiley & Sons, Inc. All rights reserved.

20 Eutrophication is a natural process, but Human activities dramatically increase the rate at which it occurs

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22 Organic Compounds Chemicals that contain carbon atoms Natural examples: sugars, amino acids, and oils Human-made examples: pesticides, solvents, industrial chemicals, and plastics 2012 John Wiley & Sons, Inc. All rights reserved.

23 Inorganic Chemicals Contaminants that contain elements other than carbon Do not degrade easily Lead Found in old paint, industrial pollutants, leaded gasoline Mercury Mercury bioaccumulates in the muscles of top predators of the open ocean Comes from burning coal Neurotoxin 2012 John Wiley & Sons, Inc. All rights reserved.

24 Toxic chemicals Pesticides, petroleum products, synthetic chemicals Arsenic, lead, mercury, acid rain, acid drainage from mines Effects include poisoned animals and plants, altered aquatic ecosystems, and decreased human health Solutions: - Issue and enforce more stringent regulations of industry - Modify industrial processes - Modify our purchasing decisions

25 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 times the 10 ppb standard. Mostly in Bangladesh, China, and West Bengal, India.

26 Sediment pollution (ie. Turbidity) Sediment in rivers can impair aquatic ecosystems Excessive amounts of suspended soil particles Originates from erosion of agricultural lands, forest soils exposed by logging, degraded stream banks, overgrazed rangelands, strip mines, and construction Problems Limits light penetration Covers aquatic animals and plants Brings insoluble toxins into waterways It dramatically changes aquatic habitats Fish may not survive Solutions: Better management of farms and forests Avoid large-scale disturbance of vegetation

27 2012 John Wiley & Sons, Inc. All rights reserved.

28 Thermal pollution Water that is too warm causes problems Warmer water holds less oxygen Dissolved oxygen decreases as temperature increases Industrial cooling heats water Removing streamside cover raises water temperature Water that is too cold also causes problems Water at the bottom of reservoirs behind dams is colder When water is released, downstream water temperatures drop suddenly, killing aquatic organisms

29 Thermal Pollution Warm water increases decomposition which decreases DO Organisms affected Temperature affects reproductive cycles, digestion rates, and respiration rates Warm water holds less DO than cold water 2012 John Wiley & Sons, Inc. All rights reserved.

30 Groundwater pollution is a difficult problem Groundwater is increasingly contaminated But is hidden from view and difficult to monitor Out of sight, out of mind Groundwater pollution is hard to address It retains contaminants for decades and longer It takes longer for contaminants to break down because of lower sunlight, microbes, and dissolved oxygen

31 Sources of groundwater pollution Some toxic chemicals occur naturally Aluminum, fluoride, sulfates Pollution from human causes wastes leach through soils Pathogens enter through improperly designed wells Leaking underground storage and septic tanks So far, the EPA has cleaned up 388,000 leaking tanks

32 Agriculture and industry pollute groundwater Agricultural pollution comes from several sources Pesticides are in most of the shallow aquifers tested Nitrates from fertilizers have caused cancer, miscarriages, and blue-baby syndrome Pathogens like Escherichia coli (E. coli) Manufacturing industries and military sites have been heavy polluters By-products seep into water from miles around Radioactive wastes will contaminate water for 750,000 years

33 Solutions Groundwater Pollution Prevention Cleanup Find substitutes for toxic chemicals Keep toxic chemicals out of the environment Install monitoring wells near landfills and underground tanks Require leak detectors on underground tanks Ban hazardous waste disposal in landfills and injection wells Store harmful liquids in aboveground tanks with leak detection and collection systems Pump to surface, clean, and return to aquifer (very expensive) Inject microorganisms to clean up contamination (less expensive but still costly) Pump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed) Fig. 21-9, p. 504

34 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.

35 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

36 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.

37 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

38 OCEAN POLLUTION Oceans, if they are not overloaded, can disperse and break down large quantities of degradable pollutants. Pollution of coastal waters near heavily populated areas is a serious problem. About 40% of the world s population lives near on or near the coast. The EPA has classified 4 of 5 estuaries as threatened or impaired.

39 Industry Nitrogen oxides from autos and smokestacks, toxic chemicals, and heavy metals in effluents flow into bays and estuaries. Cities Toxic metals and oil from streets and parking lots pollute waters; Urban sprawl Bacteria and viruses from sewers and septic tanks contaminate shellfish beds Construction sites Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight. Farms Runoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus. Closed beach Closed shellfish beds Oxygen-depleted zone Red tides Excess nitrogen causes explosive growth of toxicmicroscopic algae, poisoning fish and marine mammals. Toxic sediments Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders. Oxygen-depleted zone Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat. Healthy zone Clear, oxygen-rich waters promote growth of plankton and sea grasses, Fig , p. 505

40 OCEAN POLLUTION Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff. Figure 21-11

41 Oxygen Depletion in the Northern Gulf of Mexico A large zone of oxygendepleted water forms for half of the year in the Gulf of Mexico as a result of HAB. Figure 21-A

42 Missouri River Mississippi River Basin Ohio River Mississippi River TX LA MS LOUISIANA Mississippi River Depleted oxygen Gulf of Mexico Gulf of Mexico Fig. 21-A, p. 507

43 Case Study: The Chesapeake Bay An Estuary in Trouble Pollutants from six states contaminate the shallow estuary, but cooperative efforts have reduced some of the pollution inputs. Figure 21-12

44 OCEAN OIL POLLUTION Most ocean oil pollution comes from human activities on land. Studies have shown it takes about 3 years for many forms of marine life to recover from large amounts of crude oil (oil directly from ground). Recovery from exposure to refined oil (fuel oil, gasoline, etc ) can take years for marine life to recover.

45 OCEAN OIL POLLUTION Tanker accidents and blowouts at offshore drilling rigs can be extremely devastating to marine life (especially diving birds, left). Ex. Exxon Valdez killed over 250 thousand animals The BP oil spill threatens more than 600 animal species Figure 21-13

46 Solutions Coastal Water Pollution Prevention Reduce input of toxic pollutants Separate sewage and storm lines Ban dumping of wastes and sewage by maritime and cruise ships in coastal waters Ban ocean dumping of sludge and hazardous dredged material Protect sensitive areas from development, oil drilling, and oil shipping Cleanup Improve oil-spill cleanup capabilities Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful by-products (still under development) Require at least secondary treatment of coastal sewage Regulate coastal development Recycle used oil Require double hulls for oil tankers Use wetlands, solar-aquatic, or other methods to treat sewage Fig , p. 509

47 Great Pacific Garbage Patch Is a gyre of marine litter in the central North Pacific Ocean and estimated to be the twice the size of Texas An estimated 80% of the garbage comes from land-based sources, and 20% from ships

48 Some of these long-lasting plastics end up in the stomachs of marine birds and animals baby chicks Besides the particles' danger to wildlife, the floating debris can absorb organic pollutants from seawater, including DDT Aside from toxic effects, when ingested, some of these are mistaken by the endocrine system as estradiol, causing hormone disruption in the affected animal. These toxin-containing plastic pieces are also eaten by jellyfish, which are then eaten by larger fish. Many of these fish are then consumed by humans, resulting in their ingestion of toxic chemicals. Marine plastics also facilitate the spread of invasive species that attach to floating plastic in one region and drift long distances to colonize other ecosystems.

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50 It is best to prevent pollution It is far better to prevent pollution than use end-of-pipe treatment and cleanup Other options are not as good: Removing just one herbicide from water in the U.S. Midwest costs $400 million/year Pumping, treating, and re-injecting it takes too long Consumers can purchase sustainably made products Become involved in local riverwatch projects Urge government to pursue policies to fight pollution

51 Legislative efforts reduce pollution Water pollution was worse decades ago Citizen activism and government response resulted in legislation during the 1960s and 1970s The situation is much better now The Federal Water Pollution Control Act (1972) Renamed the Clean Water Act in 1977 It is illegal to discharge pollution without a permit Sets standards for industrial wastewater Funded sewage treatment plants

52 Enforcement of water quality is decreasing Underfunded and understaffed state and federal regulatory agencies were pressured by industries and politicians Violations of the Clean Water Act have risen to over 100,000 documented violations/year 10% of Americans are unknowingly exposed to unsafe drinking water The new EPA administrator has promised to improve Citizens pushed politicians to improve the Great Lakes The water quality of the lakes has dramatically improved

53 We treat our drinking water Technology and government regulation have improved our pollution control Treated drinking water is widespread and successful in developed nations Before water reaches the user, it is chemically treated, filtered, and disinfected The EPA sets standards for over 90 drinking water contaminants Local governments and private water suppliers must meet these standards