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Water-Sources and Pollution

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Presentation on theme: "Water-Sources and Pollution"— Presentation transcript:

1 Water-Sources and Pollution
Lecture 19 Topics: Water-Sources and Pollution Water Resources Water Availability and Use Water Pollution Water Quality Today Water Legislation U. S. World Problems

2 Glaciers in the Himalayas provide non-monsoon water into five countries for over 1.3 billion people

3 Do check the validity of the information source



6 In many areas of this world, population densities are greater than 26000 people per square mile



9 In India, monsoons last from June until September

10 Heat transfer in water occurs by both conduction and convection
Heat transfer in water occurs by both conduction and convection. Land masses transfer thermal load by conduction only, so land masses change temperature more rapidly. The imbalance in heat load creates thermal lows either over the ocean, or land. Movement of moist air follows, and uplift along mountain ranges cools the air and it rains. “CAPE” is convective available potential energy and is an indicator of air instability

11 Wheat growing areas of Pakistan and India, mapped with potential zones of conflict

12 India and Pakistan are each building huge hydroelectric dam projects less than 70 km apart

13 …and the Chinese started two projects to divert water from southern China to cities and agricultural production in the northeast



16 A serious attempt to remedy a knowledge gap about glacier melt is underway. It appears there are four “zones” of varied loss, which grow worse in the east

17 Loss of surface water flow makes water contamination worse…in this case, the concentration of arsenic

18 Water Pollution: Type and Effect
Water pollution: Any physical, biological, or chemical change in water quality that adversely affects life Point Sources - Pollution from specific locations Factories, Municipal sewage Non-Point Sources - Scattered or diffuse (no specific location of discharge) Agricultural fields, Air pollution

19 Major Categories of Pollutants

20 Types (classes) of water pollution
Infectious Pathogens Sources: improperly treated human waste, and agricultural runoff ( feedlots) Impacts: billion people in LDCs lack adequate sanitation leading to water contamination ~ 1 billion people lack clean drinking water ~ 80% of all disease in LDCs related to water quality ~ 25 million deaths/year (if you include malaria, and yellow fever) More than 500 pathogenic bacteria, viruses, and parasites can travel from human or animal excrement through water In developed countries, sewage treatment has virtually eliminated pathogens from water Drinking water disinfected via chlorination

21 Types (classes) of water pollution
Biological Oxygen-Demanding Waste (BOD) is caused by organic matter that is being decomposed: e.g., agricultural runoff and sewage Impact: Actively respiring bacteria —> depressed O2 —> depressed aquatic life O2 is removed from water by respiration (decomposer bacteria) Water with < 2 ppm dissolved O2 will support only detritivores and decomposers

22 Oxygen Sag - O2 levels decline downstream from a pollution source as decomposers metabolize waste materials





27 Nutrients that promote plant growth
Sources: Sewage, runoff, and air pollution Impact: Promotes ‘algal bloom’ —> lower light and changes in water pH —> algae death —> O2 —> depresses aquatic life Eutrophication - Process of increasing nutrient levels and biological productivity Oligotrophic - few nutrients (clear water with low biological productivity) Eutrophic - nutrient rich water (high productivity)


29 Toxic Inorganic Pollutants
Include: Toxic metals such as mercury, lead, cadmium Salts, acids, bases (in high concentrations) Sources: industrial wastes, mine runoff, homes (e.g., lead in pipes) Impacts: Lower water quality (restricts uses), and impacts on aquatic life (metals bioaccumulate) Some high bioaccumulating plants are actually used to remediate waste water

30 Organic Chemicals Include: Thousands of natural and synthetic organic chemicals found in pesticides, plastics, pigments, oil, etc. Sources: Industrial and household wastes, runoff of pesticides from high-use areas Impacts: Reduced water quality ( uses), and altered aquatic life (many organic molecules bioaccumulate)

31 Sediments - insoluble suspended matter
Sources: runoff of soil, sewage, atmospheric dust Human-induced erosion and runoff —> sediments (greatest single cause of water pollution) Impacts: Reduced light —> reduced photosynthesis —> Depressed or altered food chains Also smothers benthic life and spawning areas

32 Water Quality Today Major success story (Legislation that works plus EPA oversight) In 1950s, many rivers/lakes badly polluted (some rivers caught on fire from oil pollution!) (Lake Erie had virtually no fish) In 1999, EPA reported 91.4% of all river miles and 87.5% of all lake areas suitable for their designated uses Clean Water Act (1972) established a National Pollution Discharge System which requires a permit for any entity dumping wastes in surface waters.

33 Cuyahoga River Fires in Cleveland, Ohio 1969


35 Clean Water Act (1972) established a National Pollution Discharge System, which requires a permit for any entity dumping wastes in surface waters Discharge permits are required for all point sources No discharge allowed for 126 priority pollutants Goal was to return all U.S. surface waters to “fishable and swimmable” condition (these are the 2 key criteria established by CWA)

36 Major areas of progress under the Clean Water Act:
Most progress due to municipal sewage treatment facilities In 1997, EPA switched regulatory approaches: Now focus on watershed-level monitoring and protection States are required to identify waters not meeting water quality goals and develop approaches to meet water quality goals

37 Remaining Problem Areas (Local & Global)
Greatest problems are from non-point sources: include sediments, nutrients, and pathogens 3/4 of water pollution in the US comes from soil erosion, agricultural and urban runoff, and air pollution deposition Feedlots produce 144 million tons of waste/year Atmospheric Deposition - Contaminants from air deposited into watersheds or directly onto surface waters Great Lakes estimated to contain > 1 million pounds of the herbicide atrazine

38 Groundwater contamination
Half the US population (95% of rural population) relies on aquifers for drinking water An estimated 1 trillion gallons of contaminated water seep into the ground every day Fertilizers and pesticides contaminate aquifers and wells in rural aquifers Oil and MTBE is present in many urban aquifers Largest aquifer in San Diego Co. is contaminated with oil Natural gas extraction contaminates aquifers with dozens of unknown chemicals

39 Groundwater Pollution

40 Drinking water: 1.5 million Americans fall ill from fecal contamination annually Some pathogens resistant to treatment --- e.g., Cryptosporidium outbreaks

41 Ocean Pollution: 6 million metric tons of trash and litter tossed from ships into the ocean annually Most coastlines contaminated by oil & pollution

42 The ocean’s garbage patches
Charles Moore founded the Algalita Foundation in after sailing a catamaran from Hawaii, which took him through the Great Pacific Gyre “It began with a line of plastic bags ghosting the surface, followed by an ugly tangle of junk: nets and ropes and bottles, motor-oil jugs and cracked bath toys, a mangled tarp. Tires. A traffic cone. Moore could not believe his eyes. Out here in this desolate place, the water was a stew of plastic crap.” There is 6 times more plastic than plankton in this area, which is twice the size of Texas




46 Water pollution problems in other countries:
In Russia, only about half of the tap water supply is safe to drink In urban areas of South America, Africa, and Asia, 95% of all sewage is discharged untreated into rivers 2/3 of India’s surface waters dangerous to human health 2/3 of China’s surface water is unsafe for humans


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