Water Pollution 2011 Pearson Education Inc Freshwater pollution

Water Pollution © 2011 Pearson Education, Inc.

Freshwater pollution and its control • 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” © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

Freshwater pollution sources © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

Eutrophication is a natural process, but… • Human activities dramatically increase the rate at which it occurs © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

Sediment pollution • Sediment in rivers can impair aquatic ecosystems • Clear-cutting, mining, clearing land for housing, and cultivating farm fields expose soil to erosion • It dramatically changes aquatic habitats - Fish may not survive • Solutions: - Better management of farms and forests - Avoid large-scale disturbance of vegetation © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

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, p. H, taste, odor, hardness, dissolved oxygen - Physical indicators: color, temperature, turbidity © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc. So far, the EPA has cleaned up 388, 000 leaking tanks

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 © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

Legislative efforts reduce pollution • Water pollution was worse decades ago - Citizen activism and government response resulted in legislation during the 1960 s and 1970 s - 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 © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

We treat our wastewater • Wastewater = water people have used in some way - Household, manufacturing, stormwater runoff, etc. - It is treated before being released into the environment • 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 pollutants - Solid waste is periodically pumped out and landfilled © 2011 Pearson Education, Inc.

Municipal sewer systems • In populated areas, sewer systems carry wastewater to treatment locations • Primary treatment = physically removes contaminants in settling tanks (clarifiers) • Secondary treatment = water is stirred and aerated - Aerobic bacteria degrade organic pollutants - Water treated with chlorine (and/or ultraviolet light) is piped into rivers or the ocean • Reclaimed water is used for lawns, irrigation, or industry © 2011 Pearson Education, Inc.

A typical wastewater treatment facility • Sludge = solid material resulting from treatment - Is decomposed microbially - Then landfilled, incinerated, or used as fertilizer on cropland • Methane-rich gas created by decomposition can be burned to generate electricity © 2011 Pearson Education, Inc.

Artificial wetlands clean 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 percolates underground • They are havens for wildlife and areas for human recreation The U. S. has over 500 artificially constructed or restored wetlands © 2011 Pearson Education, Inc.

Conclusion • Obtaining future supplies of freshwater requires citizen action, legislation and regulation, technology, economic incentives, and education • With expanding population and increasing water usage, we are approaching conditions of widespread scarcity • Water pollution is already harming health, economies, and societies of both rich and poor nations • Better regulation has improved water quality in the U. S. and other developed nations © 2011 Pearson Education, Inc.