Lecture 19 Topics: Water-Sources and Pollution Water Resources Water Availability and Use Water Pollution Water Quality Today Water Legislation U. S. World Problems
Dec 11, 2015
Lecture 19 Topics:
Water-Sources and Pollution
Water Resources
Water Availability and Use
Water Pollution
Water Quality Today
Water Legislation U. S.
World Problems
Glaciers in the Himalayas provide non-monsoon water into five countries for over 1.3 billion
people
Do check the validity of the information source
In many areas of this world, population densities are greater than 26000 people per
square mile
In India, monsoons last from June until September
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
Wheat growing areas of Pakistan and India, mapped with potential zones of
conflict
India and Pakistan are each building huge hydroelectric dam projects less than 70 km
apart
…and the Chinese started two projects to divert water from southern China to cities and agricultural
production in the northeast
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
Loss of surface water flow makes water contamination worse…in this case, the
concentration of arsenic
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
Major Categories of Pollutants
Types (classes) of water pollution
Infectious Pathogens
Sources: improperly treated human waste,and agricultural runoff ( feedlots)
Impacts: 2.5 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
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
Oxygen Sag - O2 levels decline downstream from a pollution source as decomposers metabolize waste materials
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)
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
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)
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
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
Cuyahoga River Fires in Cleveland, Ohio 1969
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)
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
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
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
Groundwater contamination
Groundwater Pollution
Drinking water:
1.5 million Americans fall ill from fecal contamination annually
Some pathogens resistant to treatment
--- e.g., Cryptosporidium outbreaks
Ocean Pollution:
6 million metric tons of trash and litter tossed from ships into the ocean annually
Most coastlines contaminated by oil & pollution
The ocean’s garbage patches
Charles Moore founded the Algalita Foundation in 1998 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
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
http://www.youtube.com/watch?v=FrAShtolieg