Water Pollution

1. Water Pollution

2. Nutrient pollution • Pollution= the release of matter or energy into the environment that causes undesirable impacts on the health and well-being of humans or other organisms • Nutrient pollution from fertilizers, farms, sewage, lawns, golf courses • Leads to eutrophication • Solutions • Phosphate-free detergents • Planting vegetation to increase nutrient uptake • Treat wastewater • Reduce fertilizer application

3. Eutrophication is a natural process, but… • Human activities dramatically increase the rate at which it occurs

4. Pathogens and waterborne diseases • Enters water supply via inadequately treated human waste and animal waste via feedlots • Causes more human health problems than any other type of water pollution • Fecal coliform bacteria indicate fecal contamination of water • The water can hold other pathogens, such as giardiais, typhoid, hepatitis A

5. Monitoring for Sewage • Fecal coliform test: test for the presence of E. coli, used as indication of amt of sewage present • Indirect measure of presence of disease-causing agents

6. Presence of Coliform Bacterium • Safe drinking water: no more than 1 coliform bacterium per 100ml of water, should be zero according to WHO • Safe swimming water: no more than 200 per 100ml of water • General recreation water (boating): no more than 2000 per 100ml of water

7. Pathogens cause massive human health problems • Currently, 1.1 billion people are without safe drinking water • 2.4 billion have no sewer or sanitary facilities • Mostly rural Asians and Africans • An estimated 5 million people die per year • Solutions: • Treat sewage • Disinfect drinking water • Public education to encourage personal hygiene • Government enforcement of regulations

8. Oxygen-Demanding Waste • Sewage and other organic matter can pose a threat to oxygen availability • Waste and organic matter are broken down by microorganisms during cell respiration • These microbes can use most of the DO • BOD: biochemical oxygen demand or biological oxygen demand-amt of oxygen needed by microbes to decompose waste

9. Toxic chemicals • From natural and synthetic sources • Pesticides, petroleum products, synthetic chemicals • Arsenic, lead, mercury, acid rain, acid drainage from mines • Effects include: poisoning animals and plants, altering aquatic ecosystems, and affecting human health • Solutions: • Legislating and enforcing more stringent regulations of industry • Modify industrial processes • Modify our purchasing decisions

10. Lead and Mercury • Incinerator ash dumped in landfills contains lead • Old factories w/out air pollution control devices • Residues from pesticides and fertilizers • Coal contains traces of mercury, released in air when burned • Waste incinerators • Smelting of metals: lead, copper, & zinc • Mercury vaporizes into atmosphere or goes out w/waste H2O

11. Sediment Pollution • Examples: clay, silt, sand, & gravel • Sources: erosion of agricultural land, forest soils from logging, overgrazed rangeland, strip mines, & construction • Effects: reduces light penetration, covers aquatic organisms, brings in insoluble toxic pollutants and disease-causing agents

12. Thermal pollution • Warmer water holds less oxygen • Dissolved oxygen decreases as temperature increases • Industrial cooling heats water • Removing streamside cover also raises water temperature • Water that is too cold causes problems • Water at the bottom of reservoirs is colder • When water is released, downstream water temperatures drop suddenly and may kill aquatic organisms

13. Point and nonpoint source water pollution • Point source water pollution = discrete locations of pollution • Factory or sewer pipes • Nonpoint source water pollution = pollution from multiple cumulative inputs over a large area • Farms, cities, streets, neighborhoods • The U.S. Clean Water Act • Addressed point sources • Targeted industrial discharge • In the U.S., nonpoint sources have a greater impact on quality • Limit development on watershed land surrounding reservoirs

14. Freshwater pollution sources

15. Indicators of water quality • Scientists measure properties of water to characterize its quality • Biological indicators: presence of fecal coliform bacteria and other disease-causing organisms • Chemical indicators: pH, nutrient concentration, taste, odor, hardness, dissolved oxygen • Physical indicators: turbidity, color, temperature

16. Groundwater pollution is a serious problem • Groundwater is increasingly contaminated, but is hidden from view • Difficult to monitor • Out of sight, out of mind • Retains contaminants for decades and longer • Takes longer for contaminants to breakdown in groundwater because of the lower dissolved oxygen levels

17. 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 • Hazardous wastes are pumped into the ground • Underground storage septic tanks may leak

18. Plant Nutrients • Examples: nitrates and phosphates • Plant nutrients are needed for a healthy ecosystem, in excess it’s harmful • Sources: Human and animal wastes, plant residues, atmospheric deposition, runoff of agricultural and urban fertilizers • Effects: excessive plant growth, high BOD, decrease in DO, which causes fish kills

19. The “Dead Zone” in the Gulf of Mexico • Runoff of fertilizer and manure from farms and ranches in such states as Iowa, Wisconsin, and Illinois • The “dead zone” in the Gulf of Mexico is nearly as large as the state of NJ • “Dead zone” extends from the seafloor up into the water column, sometimes within a few meters of the surface • Bacteria thrives in the dead zone

20. “Dead Zone” con’t • Hypoxia (oxygen-free condition) caused by large algal blooms that die & are decomposed by bacteria • Ways to reduce nutrients: modify farming methods(20% less fertilizer), restore former wetlands in the Mississippi River watershed, address sewage treatment plants and airborne nitrogen oxides from automobile emissions

21. Legislative efforts reduce pollution • Federal Water Pollution Control Act (1972) • Renamed the Clean Water Act in 1977 • Illegal to discharge pollution without a permit • Standards for industrial wastewater • Funded sewage treatment plants • Because of legislation, the situation is much better than it was • Other nations have also reduced pollution

22. We treat our drinking water • Technology has improved our pollution control • The EPA sets standards for more than 80 drinking water contaminants • Local governments and private water suppliers must meet • Before water reaches the user • It is chemically treated, filtered, and disinfected

23. It is better to prevent pollution • It is far better to prevent groundwater contamination than correct it • Other options are not as good: • Removing just one herbicide from water costs $400 million • Pumping, treating, and re-injecting it takes too long • Restricting pollutants above aquifers would shift pollution elsewhere • Consumers can purchase environmentally friendly products • Become involved in local “river watch” projects

24. Treating wastewater • Wastewater= water that has been used by people in some way • Sewage, showers, sinks, manufacturing, storm water runoff • Septic systems = the most popular method of wastewater disposal in rural areas • Underground septic tanks separate solids and oils from wastewater • The water drains into a drain field, where microbes decompose the water • Solid waste needs to be periodically pumped and landfilled

25. Municipal sewer systems • In populated areas, sewer systems carry wastewater • Physical, chemical, and biological water treatment • Primary treatment = the physical removal of contaminants in settling tanks (clarifiers) • Secondary treatment = water is stirred and aerated so aerobic bacteria degrade organic pollutants • Water treated with chlorine is piped into rivers or the ocean • Some reclaimed water is used for irrigation, lawns, or industry

26. A typical wastewater treatment facility

27. Artificial wetlands • Natural and artificial wetlands can cleanse wastewater • After primary treatment at a conventional facility, water is pumped into the wetland • Microbes decompose the remaining pollutants • Cleansed water is released into waterways or percolated underground • Constructed wetlands serve as havens for wildlife and areas for human recreation • More than 500 artificially constructed or restored wetlands exist in the U.S.