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Chapter 22 Water Pollution Overview of Chapter 22 o Types of Water Pollution • • • • • • • o o o Sewage Disease-causing agents Sediment pollution Inorganic plant and algal nutrients Organic compounds Inorganic chemicals Thermal pollution Water Quality Today Improving Water Quality Laws Controlling Water Pollution Types of Water Pollution o Water pollution • • o Major water pollution issue globally • o Any physical or chemical change in water that adversely affects the health of humans and other organisms Varies in magnitude by location Lack of disease-free water Eight categories • Sewage, disease-causing agents, sediment pollution, inorganic plant and algal nutrients, organic compounds, inorganic chemicals, radioactive substances, and thermal pollution 1. Sewage o The release of wastewater from drains or sewers • o Includes human wastes, soaps, and detergents Causes 2 serious environmental problems: • Enrichment • • Fertilization of a body of water by high levels of plant and algal nutrients (nitrogen and phosphorus) Increase in Biological Oxygen Demand (BOD) • • Amount of oxygen needed by microorganisms to decompose biological wastes As BOD increases Dissolve Oxygen (DO) decreases Sewage Sewage- Eutrophication o Oligotrophic • Unenriched, clear water that supports small populations of aquatic organisms Sewage- Eutrophication o Eutrophic• • Slow-flowing stream, lake or estuary enriched by inorganic plant and algal nutrients such as phosphorus Often due to fertilizer or sewage runoff 2. Disease-causing Agents o Infectious organisms that cause diseases • o Originate in the wastes of infected individuals Common bacterial or viral diseases: • Typhoid, cholera, bacterial dysentery, polio, and infectious hepatitis Disease-causing Agents o Monitored by testing for presence of E. coli in the water via a fecal coliform test • Indicates the presence of pathogenic organisms Types of Water Pollution o Monitoring for Sewage (Fecal Coliform Test) – small sample of water passed through filter to trap bacteria, transferred to a petri dish with nutrients; incubated until greenish colonies form, which can be counted to indicate the number of E. coli in the original sample Fecal Coliform Test - Results o o o o Safe drinking water = no more than 1 coliform bacterium per 100 mL of drinking water (1/2 cup) Safe swimming water = no more than 200 bacteria per 100 mL of water Safe recreational boating = no more than 2,000 per 100 mL of water Raw Sewage = usually several million coliform bacteria per 100 mL of water! 3. Sediment Pollution o Excessive amounts of suspended soil particles • o Originates from erosion of agricultural lands, forest soils exposed by logging, degraded stream banks, overgrazed rangelands, strip mines, and construction Problems • • • Limits light penetration thereby decreasing photosynthetic activity Covers aquatic animals and plants, providing less shelter for aquatic organisms Brings insoluble toxins into waterways 4. Inorganic Plant and Algal Nutrients o Chemicals such as nitrogen and phosphorus that stimulate the growth of plants and algae • o Sources: • o Harmful in large concentrations Human and animal wastes, plant residues, atmospheric deposition, and fertilizer runoff Causes: • Enrichment, bad odors, and a high BOD Inorganic Plant and Algal NutrientThe Dead Zone 5. Organic Compounds o Chemicals that contain carbon atoms • • Natural examples: sugars, amino acids, and oils Human-made examples: pesticides, solvents, industrial chemicals, and plastics Organic Compounds 2002 U.S. Geological Survey of 139 streams in the United States found trace amounts of: antibiotics, ibuprofen, acetaminophen, insect repellents, fragrances, caffeine, steroids (like hormones from birth control pills) What is the effect of trace amounts of these in our water supply????? 6. Inorganic Chemicals o Contaminants that contain elements other than carbon • o o Do not degrade easily Lead • o Examples: acids, salts, and heavy metals Found in old paint, industrial pollutants, leaded gasoline Mercury • Mercury bioaccumulates in the muscles & fat of top predators of the open ocean Inorganic Chemicals Mercury: Vaporizes even at room temperature (so can be inhaled!) Coal-fired power plants mostly to blame for mercury exposure Under the current Clean Air Act, mercury emissions are NOT mandated for power plants (unlike sulfur emissions) Municipal waste incinerators, smelting of metals, industrial chemicals also expose us to mercury 7. Radioactive Substances o o Contain atoms of unstable isotopes that spontaneously emit radiation Sources • • • • Mining Processing radioactive materials Nuclear power plants Natural sources 8. Thermal Pollution o o Occurs when heated water produced during industrial processes is released into waterways Organisms affected • • Temperature affects reproductive cycles, digestion rates, and respiration rates Warm water holds less DO than cold water Water Quality Today o o Two Types of Water Pollution -Point Source Pollution • • o water pollution that can be traced to a specific origin Discharge via pipes, sewage, and ditches -Non-point Source Pollution • • • Pollutants that enter bodies of water over large areas rather than being concentrated at a single point of entry Diffuse, but its cumulative effect is very large Ex: runoff from agricultural fields or parking lots Water Pollution from Agriculture o Agriculture is leading source of water pollution in US (72% of the pollution) • • o Animal wastes and plants residues have high BOD Chemical pesticides can leach into groundwater Almost all streams and rivers are polluted with agricultural pesticides Municipal Water Pollution Industrial Wastes in Water o Different industries generate different pollutants • • o Food processing plants- high BOD Paper mills- High BOD and toxic compounds Many industries recover toxins before they go into the waste stream Case-In-Point Green Chemistry Examples of Green Chemistry o o Researchers at Carnegie-Mellon U. are using TAML’s (tetra-amido-macro-cyclic ligands) for helping break down synthetic substances before dumping into rivers Changing chemical processes to use fewer synthetic chemicals in industry • o Plastic bottles can now be made from sugars, with no use of harmful chemicals, and also break down in the environment after use Dry cleaners in California can no longer use perchloroethylene (perc), and have found less harmful alternatives Groundwater Pollution (1/2 the people in the U.S. get their drinking water from groundwater!) Water Pollution in Other Countries o Lake Maracaibo, Venezuela • 10,000 oil wells tap lake bottom • • • drilling platforms throughout the lake…pipelines running to refineries on land…10,000 oil wells have been drilled…much oil spilled! Agricultural wastes from local fields Unit recently raw human waste polluted the lake Water Pollution in Other Countries o Po River, Italy • • • • Similar to Mississippi River Pollutants: Sewage, industrial wastes, sediment >16 million Italians depend on the river for drinking water Pollution is high • • Swimming and fishing prohibited Cleanup will require a national management plan and may take decades Water Pollution in Other Countries o Ganges River, India • • • Used for bathing and washing clothing Sewage and industrial waste discharged into river Ganga Action Plan initiated by government • Construction of 29 sewage treatment plants Improving Water QualityPurification of Drinking Water o o In US most municipal water supplies are treated, typically with chlorine! First step…water is collected from water or reservoir (dam may be involved, or groundwater wells and water towers used) Improving Water QualityPurification of Drinking Water o o o Treated water distributed to customers Sewer lines bring sewage to treatment plant Sewage treated at sewage treatment plant Purification of Drinking Water o o Chlorine Dilemma Chlorine kills disease causing organisms! • • BUT - Chlorine byproducts are linked to numerous cancers, miscarriages and birth defects Peru stopped using chlorine • o Fluoridation • • o 1991- huge cholera epidemic that infected 300,000 people Prevents tooth decay Linked to cancer, kidney disease With both of these…the risk must be compared to the benefits! Municipal Sewage Treatment o Primary treatment • o Removing suspended and floating particles by mechanical processes (usually screens) Secondary treatment • Treating wastewater biologically to decompose suspended organic material; reduces BOD Municipal Sewage Treatment o Sewage Sludge • • o Solids remaining after primary and secondary sewage treatment has been completed This material is either landfilled or used as composting for farms (may contain mercury and other harmful toxins) Tertiary treatment • • Advanced wastewater treatment methods that are sometimes employed after primary and secondary treatments (usually an additional bacterial treatment) Reduce phosphorus and nitrogen Municipal Sewage Treatment Individual Septic SystemSeptic Tank Individual Septic SystemDrain Field Laws Controlling Water Pollution o o Citizen Watchdogs to Monitor Pollution Safe Drinking Water Act (1974) • • o Set uniform federal standards for drinking water Maximum contaminant levels and MCL goals were established for many common water pollutants! Clean Water Act (1972) • • • EPA sets up and monitors National Emissions Limitations Effectively improved water quality from point sources Still largely ineffective at controlling NONPOINT sources! Laws that Protect Groundwater o o o Safe Drinking Water Act (1974) Resource, Conservation and Recovery Act (1976) Comprehensive Environmental Response, Compensation, and Liability Act (Superfund – 1980)