Water Pollution CHAPTER 19

Key Concepts  Types, sources, and effects of water pollutants  Major pollution problems of surface water  Major pollution problems of groundwater  Reduction and prevention of water pollution  Drinking water quality

Types and Sources of Water Pollution  Point sources: discharge pollutants at specific locations. (factories, sewage treatment plants, etc.)  Nonpoint sources: cannot be traced to any single site of discharge.  Biological oxygen demand: the amount of dissolved oxygen needed by aerobic decomposers to break down the organic materials in a certain volume of water over a 5-day incubation period. WaterQualityGood 8-9 Do (ppm) at 20C Slightlypolluted Moderatelypolluted Heavilypolluted Gravelypolluted Below 4.5 Below 4 Fig. 19.3, p. 485

Pollution of Streams Flowing streams can recover rapidly from degradable, oxygen-demanding wastes through dilution and bacterial decay. Clean Zone DecompositionZone Septic Zone Recovery Zone Clean Zone Normal clean water organisms (Trout, perch, bass, mayfly, stonefly) Trash fish (carp, gar, Leeches) Fish absent, fungi, Sludge worms, bacteria (anaerobic) Trash fish (carp, gar, Leeches) Normal clean water organisms (Trout, perch, bass, mayfly, stonefly) 8 ppm Dissolved oxygen Biological oxygen demand Oxygen sag 2 ppm 8 ppm Concentration Types of organisms Time of distance downstream Direction of flow Point of waste or heat discharge

Pollution of Lakes Discharge of untreated municipal sewage (nitrates and phosphates) Nitrogen compounds produced by cars and factories Discharge of treated municipal sewage (primary and secondary treatment: nitrates and phosphates) Discharge of detergents ( phosphates) Natural runoff (nitrates and phosphates Manure runoff From feedlots (nitrates and Phosphates, ammonia) Dissolving of nitrogen oxides (from internal combustion engines and furnaces) Runoff and erosion (from from cultivation, mining, construction, and poor land use) Runoff from streets, lawns, and construction lots (nitrates and phosphates) Lake ecosystem nutrient overload and breakdown of chemical cycling Fig. 19.7, p. 491 Eutrophication: natural nutrient enrichment of lakes. Cultural eutrophication: accelerated in urban areas. Plants and algae grow, die, decomposition by aerobic bacteria lowers levels of DO which kills aquatic life, reduce biodiversity.

Case Study: The Great Lakes Great Lakes drainage basin Most polluted areas, according to the Great Lakes Water Quality Board “Hot spots” of toxic concentrations in water and sediments Eutrophic areas CANADA WISCONSIN MINNESOTA IOWA ILLINOIS INDIANA OHIO PENNSYLVANIA NEW YORK MICHIGAN Nipigon Bay Thunder Bay Silver Bay St. Louis R. Jackfish Bay St. Mary’s R. Spanish R. Penetary Bay Sturgeon Bay Saginaw Bay Saginaw R. System St. Clair R. Detroit R. Rouge R. Raisin R. Maumee R. Black R. Rocky R. Cuyahoga R. Ashtabula R. Thames R. Grand R. Niagara Falls Niagara R. Buffalo R. St. Lawrence R. Why are the Great Lakes prone to pollution?

Groundwater Pollution: Sources Waste lagoon, pond, or basin Mining site Pumping well Water pumping well Sewer Cesspool, septic tank Hazardous waste injection well Buried gasoline and solvent tanks Landfill Road salt Unconfined freshwater aquifer Confined freshwater aquifer Confined aquifer Discharge Leakage from faulty casing Groundwater Groundwater flow Groundwater cannot cleanse itself like surface water because: 1. Flows slowly2. Less bacteria3. Cold temps, slows react On human scale, nondegradable wastes (Pb, Arsenic, Fl) remain.

Groundwater Pollution Prevention  Monitoring aquifers  Leak detection systems  Strictly regulating hazardous waste disposal  Storing hazardous materials above ground

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; sewage adds nitrogen and phosphorus. Urban sprawl Bacteria and viruses from sewers and septic tanks contaminate shellfish beds and close beaches; runoff of fertilization from lawns adds nitrogen and phosphorus. Construction sites Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight. Farms Run off of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus. Red tides Excess nitrogen causes explosive growth of toxic microscopic algae, poisoning fish and marine mammals. Healthy zone Clear, oxygen-rich waters promote growth of plankton and sea grasses, and support fish. Oxygen-depleted zone Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat. Toxic sediments Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders. Closed shellfish beds Closed beach Oxygen-depleted zone Fig , p. 489 Ocean Pollution

Case Study: Chesapeake Bay  Largest US estuary  Relatively shallow  Slow “flushing” action to Atlantic  Major problems with dissolved O 2 Drainagebasin No oxygen Low concentrations of oxygen PENNSYLVANIA NEW YORK WESTVIRGINIA MARYLAND DELAWARE NEW JERSEY ATLANTIC OCEAN VIRGINIA Cooperstown Harrisburg Baltimore Washington Richmond Norfolk Chesapeake Bay

Oil Spills  Sources: offshore wells, tankers, pipelines and storage tanks  Effects: death of organisms, loss of animal insulation and buoyancy, smothering  Significant economic impacts  Mechanical cleanup methods: skimmers and blotters  Chemical cleanup methods: coagulants and dispersing agents

Solutions: Preventing and Reducing Surface Water Pollution Nonpoint Sources Point Sources  Reduce runoff  Buffer zone vegetation  Reduce soil erosion/runoff  Clean Water Act  Water Quality Act

Technological Approach: Septic Systems  Require suitable soils and maintenance Household wastewater Perforated pipe Distribution box (optional) Septic tank Manhole (for cleanout) Drain field Vent pipe Nonperforated pipe Gravel or crushed stone

Technological Approach: Sewage Treatment  Mechanical and biological treatment Raw sewage from sewers Bar screen Grit chamber Settling tankAeration tankSettling tank Chlorine disinfection tank Sludge Sludge digester Activated sludge Air pump (kills bacteria) To river, lake, or ocean Sludge drying bed Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Primary Secondary

Technological Approach: Advanced Sewage Treatment  Removes specific pollutants Effluent from Secondary treatment Alum flocculation plus sediments Activated carbon Desalination (electrodialysis or reverse osmosis) Nitrate removal Specialized compound removal (DDT, etc.) 98% of suspended solids 90% of phosphates 98% of dissolved organics Most of dissolved salts Recycled to land for irrigation and fertilization To rivers, lakes, streams, oceans, reservoirs, or industries

Technological Approach: Using Wetlands to Treat Sewage (1) Raw sewage drains by gravity into the first pool gravity into the first pool and flows through a long and flows through a long perforated PVC pipe into perforated PVC pipe into a bed of limestone gravel. a bed of limestone gravel. (3) Wastewater flows through another perforated pipe another perforated pipe into a second pool, where into a second pool, where the same process is repeated. the same process is repeated. (2) Microbes in the limestone gravel break down the sewage into break down the sewage into chemicals, that can be absorbed chemicals, that can be absorbed by the plant roots, and the gravel by the plant roots, and the gravel absorbs phosphorus. absorbs phosphorus. (4) Treated water flowing from the second pool is nearly free of second pool is nearly free of bacteria and plant nutrients. bacteria and plant nutrients. Treated water can be recycled Treated water can be recycled for irrigation and flushing toilets. for irrigation and flushing toilets. 45 centimeter layer of limestone gravel coated with decomposing bacteria First concrete poolSecond concrete pool Sewage Wetland type plants plants Treatedwater

Drinking Water Quality  Safe Drinking Water Act  HOW CAN WATER POLLUTION BE PREVENTED?  Bottled water 10 to 20 percent Greater than 20 percent Not tested Contaminated Probability