WATER USES AND POLLUTION (CH. 20-21)
•Water, liquid and solid, covers more than 70% of world’s surface.
More than 370 billion billion gallons.
World water use
Future water scarcity
•An estimated third of the world's population currently lives in water-stressed countries. This is set to increase
to two-thirds within 25 years. Africa and Asia are already hard-hit by water stress. Increasing populations will
create more pressure in the coming decades.
Water soaring use
•The world's population has tripled in the last 100 years, but water use has increased sixfold. A surge in water
use in agriculture is responsible for a large part of the increase.
•The amount of water on Earth is fixed. Less than 0.01% of the planet's 1.4 billion cubic kilometres is easily
accessible freshwater in lakes and rivers. About a fifth of the water used worldwide comes from the 30% of the
world's freshwater which is stored in groundwater.
Balancing the Water Budget
•Oceans account for 86% of total evaporation.
Ninety percent of water evaporated from the ocean falls back on ocean as rain.
-Remaining 10% is carried by prevailing winds over continents.
MAJOR WATER COMPARTMENTS
Together, oceans contain more than 97% of all liquid water in the world.
-Contain 90% of world’s living biomass.
-Moderate earth’s temperature.
Average residence time of water in the ocean is about 3,000 years.
Major Water Compartments
•Glaciers, Ice, and Snow
2.4% of world’s water is classified fresh.
-90% in glaciers, ice caps, and snowfields.
As recently as 18,000 years ago, one-third of continental landmass was covered by glacial ice sheets.
Now, Antarctic glaciers contain nearly 85% of all ice in the world.
Sea ice comes from ocean water, but salt is excluded during freezing.
•Describes the circulation of water as it:
Evaporates from land, water, and organisms. (Transpires from plants)
-Enters the atmosphere.
Condenses and precipitates back to the earth’s surfaces.
Moves underground by infiltration or overland runoff into rivers, lakes and seas.
•Any physical, biological, or chemical change in water quality that adversely affects living organisms can be
Types of Water Pollution
•Disease Causing Agents (pathogens): i.e., bacteria, viruses, parasites, worms (often come from sewage,
human and animal wastes) (cause diseases such as: typhoid fever, cholera, worms that cause
•Toxic Wastes: heavy metals (mercury, arsenic, etc.)
•Water-Soluble Inorganic Materials: nitrates and phosphates, cause excessive growth of algae, then they die
-> decompose. This depletes O2 content (kills fish)
Types of Water Pollution (cont.)
•Organic Chemicals: oil, gas, plastic, pesticides, detergents, ext.
•Sediments or Suspended Matter: particles of soil/solid that stay suspended in water (make it cloudy),
•Thermal Pollution: rise in water temp b/c of heat absorbed in water to cool power plants
•Genetic Pollution: deliberate or accidental addition of nonnative species disrupts aquatic systems and crowd
out natives: reduces biodiversity
Pollution of Lakes
Nutrient pollution in water
•Oligotrophic: deep, nutrient-poor, water very clear, low nutrients and organic matter, low plankton and algae.
Typical of colder climates.
shallower, nutrient rich, murky with phytoplankton, high nutrients, increased number of plankton,
algae. Common in areas where there is agricultural runoff, also typical of warmer climates (i.e. Lake
Water Pollution Sources
Atmospheric Deposition - Contaminants carried by air currents and precipitated into watersheds or directly
onto surface waters.
-Mercury in Everglades from coal burning
Sewage: water that has been contaminated/used by people
-sources include Toilets, sinks, dishwashers, washing machines, and industrial processes.
Agriculture, industry, waste disposal, urban runoff, mining, construction, erosion, transportation
•About half the US population, and 95% of rural residents, depend on underground aquifers for drinking water.
•Aquifers - Porous layers of sand, gravel, or rock lying below the water table.
Artesian - Pressurized aquifer intersects the surface. (Water flows without pumping)
•Recharge Zone - Area where water infiltrates into an aquifer.
Recharge rate is often very slow.
-Presently, groundwater is being removed faster than it can be replenished in many areas.
•Withdrawing large amounts of groundwater in a small area causes porous formations to collapse, resulting in
Sinkholes form when an underground channel or cavern collapses.
Saltwater intrusion can occur along coastlines where overuse of freshwater reservoirs draws the water table
low enough to allow saltwater to intrude.
•Estimates suggest many societies could save as much as half of current domestic water usage without great
sacrifice or serious change in lifestyle.
Largest domestic use is toilet flushing.
-Small volume of waste in large volume of water.
-Significant amounts of water can be reclaimed and recycled.
Purified sewage effluent
WATER POLLUTION CONTROL
Cheapest and most effective way to reduce pollution is avoid producing it or releasing it into environment.
-i.e. Studies show as much as 90% less road salt can be used without significantly affecting winter road safety.
Human Waste Disposal
•More than 500 pathogenic bacteria, viruses, and parasites can travel from human or animal excrement
Municipal Sewage Treatment
•Primary Treatment - Physical separation of large solids from the waste stream.
•Secondary Treatment - Biological degradation of dissolved organic compounds.
Effluent from primary treatment transferred into trickling bed, or aeration tank
-Effluent from secondary treatment is usually disinfected
(chlorinated) before release into nearby waterway.
Municipal Sewage Treatment
•Tertiary Treatment - Removal of plant nutrients (nitrates and phosphates) from secondary effluent.
Use chemicals, natural wetlands, and/or bioremediation agents.
Bioremediation: using bacteria to digest contamination or waste.
Municipal Sewage Treatment
Consequences of water pollution
•Ingestion of heavy metals can cause brain, liver, kidney damage, cancers, coma and death.
•Harms living organisms: crude oil spills kill thousands of birds, mammals, and other water organisms
•when large amounts of nitrates and phosphates enter waterways, they cause increased growth of algae and
aquatic plants. As plants decompose, amount of oxygen in water drops and many animal communities die out
Consequences of water pollution (cont.)
•Thermal pollution: comes from power plants and industrial facilities. Water from lakes/streams pumped into
pipes to be used as coolant in industrial processes
•hot water is then returned to lakes/streams. Increased water temperature decreases amount of dissolved
oxygen in water, organisms suffocate, eggs/larvae die.
•Industryoften threatens to move to other areas to avoid fines and to get water pollution laws suspended.
Laws and legislation protecting water
•Growing public concern for controlling water pollution led to enactment of Federal Water Pollution Control Act
of 1972, commonly known as the Clean Water Act.
•regulates discharges of pollutants in U.S. EPA given authority to implement pollution control programs, set
wastewater standards for industry and water quality standards for all contaminants in surface waters. The Act
makes it unlawful for any person to discharge any pollutant from a “point source” (specific source or location)
into navigable waters.
AIR POLLUTION CHAPTER 22
•anything in air that adversely affects living organisms.
•Air pollution first became a problem during Industrial Revolution (1700s), burning of large amounts of coal
•Types: 1) particulates, 2) gases – chemical compounds
1. Particulates: tiny solids suspended in atmosphere.
ex: ash, dust, and soot (from burning organic matter), liquid droplets in smoke or smog, traces of lead, iron,
and copper, and pesticides, herbicides, plant pollen, and fertilizer present in air
•Because of size, particulates are easily inhaled and can become trapped in lungs.
2. Gases and chemicals
•Gases / chemicals suspended in the air. Can come from burning trash, fossil fuels, etc. Also generated when
you paint, chemical processes, commercial products
NATURAL SOURCES OF AIR POLLUTION
•Natural Fires - Smoke
•Volcanoes - Ash and Acid components
•Sea Spray - Sulfur
•Vegetation - Volatile organic compounds
•Bacterial Metabolism - Methane
•Dust (sand storms)
•Viruses and Bacteria
THE AIR AROUND US
•Approximately 14 million metric tons of pollution are released annually into atmosphere in U.S., produced by
Worldwide emissions total around 2 billion metric tons.
•Developed countries have been improving air quality, while air quality in developing world is getting worse.
Outdoor Air Pollution
Anthropogenic (human caused) Air Pollution
•Burning fossil fuels
•Internal combustion engines
Transport (cars, planes, trains, ships, etc.)
•Human-caused fires, deforestation
•US Clean Air Act designated seven major (conventional or criteria) pollutants for which maximum ambient air
levels are mandated.
•Fine aerosols can be carried great distances by wind currents.
Increasingly, sensitive monitoring equipment has begun to reveal industrial contaminants in places usually
considered among the cleanest in the world.
-Contaminants trapped by winds at the north pole, concentrate at high latitudes and eventually fall out as snow
and ice and enter the food chain.
Indoor Air Pollution
•EPA found indoor concentrations of toxic air pollutants are often higher than outdoor.
People generally spend more time indoors.
Smoking is significant air pollutant in US.
-400,000 die annually from diseases related to smoking.
Associated costs are estimated at $100 billion annually.
Indoor Air Pollution
•Less Developed Countries also suffer from indoor air pollution.
Organic fuels make up majority of household energy.
-Often burned in smoky, poorly ventilated heating and cooking fires.
Indoor Air Pollution/Sick Building Syndrome
EFFECTS OF AIR POLLUTION
Bronchitis, emphysema, cancer, allergies, lung disease
EPA estimates each year 400,000 people die prematurely from illnesses related to air pollution.
-Likelihood of suffering ill health is related to intensity and duration of exposure.
Inhalation is most common route, but absorption through skin and consumption via food can also occur.
•Chemical pollutants can directly damage plants, or can cause indirect damage by disrupting normal growth
and development patterns.
Thin, acidic soils and oligotrophic lakes of southern Norway and Sweden have been severely affected by acid
-Generally, reproduction is most sensitive stage in fish life cycles.
In early 1970’s, evidence began to accumulate suggesting air pollutants are acidifying many NA lakes.
Air pollution and depositions of atmospheric acids are believed to be important causes of forest destruction in
•Buildings and Monuments
Limestone and marble are destroyed by air pollution at an alarming rate.
Corroding steel in reinforced concrete weakens buildings, roads, and bridges.
•Discovered in 1985, stratospheric ozone levels dropping rapidly
Occurring since at least 1960.
•At ground-level, ozone is a pollutant, but in stratosphere it screens UltraViolet radiation.
•Consequences: skin cancer, phytoplankton decline, decreased plant productivity, global warming
CAUSES OF OZONE DEPLETION
•CFCs: chloroflourocarbons, chemical compound that is man-made
•Uses: refrigeration (freon), aerosols (propellants)
•Currently most countries have agreed to reduce use of CFCs in propellants. Montreal Protocol.
Greenhouse effect: Greenhouse effect: certain gases in atmosphere trap heat in lower atmosphere
• without it life would not exist as it does (covered by water)
• Carbon dioxide has largest effect on amount of heat trapped
The Natural Greenhouse Effect - Greenhouse Gases
•Carbon Dioxide - Fossil-fuel burning.
-Atmospheric levels increasing steadily.
•Methane - Ruminants, Coal-mines
-Absorbs more infrared than CO2.
•Chlorofluorocarbons (CFC’s) - Refrigerants
-Declined in recent years
•Nitrous Oxide - Burning organic material
•Sulfur Hexafluoride - Electrical insulation
Global Warming = an accelerated enhancement in Earth's greenhouse effect.
• caused by burning fossil fuels, agriculture, deforestation and use of CFC's.
• developed countries -> 60% of CO2 emissions: US-23% ; China-14% ; Russia-7% ; Japan-5% (2000)
• likely to affect climate for centuries
Human-Caused Global Climate Change
•Scientists estimates average global temperature will increase over next century by 1.4 - 5.8 C (2.5 - 10.4 F).
Difference between current temperature and last ice age is only 5o C.
-Every year of 1990’s was among 15 hottest of past millennium.
patterns and rates likely to be affected.
Possible signs of global warming
• Increased retreat of glaciers
• warm-climate organisms slowly migrate/ disperse toward poles
• warmer water = coral reefs bleaching
• Sea levels rise
•Changes may be too abrupt for some organisms = extinctions?
Model predictions of rises in sea level
Scientists use climate models to estimate changes in future sea level rise, one of the expected effects of global
warming. This graph shows sea level changes predicted by six climate models, each of which ran 35 different
greenhouse gas emission scenarios. The center dark region shows the predicted sea level rise for the models
averaged over the 35 emission scenarios. The lighter blue region shows the range of the maximum and
minimum model predictions. The outer, lightest blue section includes the uncertainties of land-ice changes,
permafrost changes and sediment deposition (not including the possiblity of melting of the West Antarctic Ice
Sheet). The top curve is the extreme worst case scenario and the bottom curve shows the least expected
AIR POLLUTION CONTROL
Remove particles physically by trapping them in a porous mesh which allows air to pass through but holds
Electrostatic Precipitators - Fly ash particles pick up electrostatic charge as they pass between large
electrodes in waste stream, and accumulate on collecting plate.
CLEAN AIR LEGISLATION
•Clean Air Act (1963) - First national air pollution control.
•Clean Air Act (1970) rewrote original Act.
Identified critical pollutants.
Established ambient air quality standards.
-Primary Standards - Human health
-Secondary Standards - Materials, environment, aesthetic and comfort.
Clean Air Act
•Revision (1990) - Included provision for:
Toxic Air Pollutants
Marketing Pollution Rights
Volatile Organic Compounds
•Revision (1997) - Stricter standards
CURRENT AND FUTURE CONDITIONS
•In the United States, air quality has improved dramatically in the last decade in terms of major large-volume
Cities where pollution is largely from traffic still have serious air quality problems.
•Major metropolitan areas of many developing countries are growing at explosive rates, and environmental
quality is very poor.