Environmental Science

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Environmental Science

• Chapter 25 Human Society and the Biosphere

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25.1 Urban Wastes

• Most of the societies on the planet are based on
  consumerism.
• Consumerism occurs in a society when the economy
  is set up to provide goods that are used then
  discarded.
• Planned obsolescence is the concept of designing
  products to fail after a pre-determined set of
  time. Ex cars, computers, mens razors
• Some manufacturing companies use planned
  obsolescence to maximize their profit potential
  in a marketplace.

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25.1 Urban Wastes

• The average American throws away almost 2
  kilograms (5lbs.) of trash and garbage everyday.
• Garbage includes food wastes from domestic and
  commercial sources.
• Something that is biodegradable can be broken
  down into reusable compounds by decomposers in
  the environment.
• Garbage is considered biodegradable.
• Trash is non-food waste, such as glass, aluminum,
  some plastics, and tin cans.

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25.1 Urban Wastes

• Waste stream is the flow of waste materials into
  the environment.
• Some materials of the waste stream are valuable,
  but are mixed with other materials. Ex silver in
  electronic equipment
• Landfills consist of buried trash and garbage,
  usually found outside the city.
• Bacteria in the soil breakdown the biodegradable
  wastes producing CO2, H2O, and CH4 (methane).

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25.1 Urban Wastes

• Landfills are closely regulated and inspected to
  ensure contamination does not reach the public.
• Toxic substances can cause damage to living
  tissues through contact or absorption.
• Seepage of rain water through a landfill can
  spread hazardous and toxic substances far beyond
  the landfill boundaries.

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25.1 Urban Wastes

• Incineration, the burning of solid wastes, is
  another method of waste treatment used
  extensively by cities.
• Combustion is never complete, even in the most
  efficient incinerators.
• Ash, soot, organic compounds, and heavy metals
  often enter the atmosphere even with exhaust gas
  scrubbers required in smokestacks.
• Acid rain is a possible byproduct of incineration.

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25.1 Urban Wastes

• The first city sanitation systems were built
  about 5,000 years ago in cities of the Indus
  River valley.
• Sewers were built in Rome, Italy more than 2,000
  years ago and are still in use today.
• Human and animal waste can contain over 500
  different types of pathogens. Ex. Typhoid,
  cholera, and dysentery, among others.
• The development of the flushing toilet and
  treatment facilities improved human health
  greatly.
• Sewage is wastewater from homes, businesses, or
  industry that contain cooking, cleaning, or
  bathroom wastes.

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25.1 Urban Wastes

• Primary treatment of sewage involves straining
  large solids from the waste-stream.
• The remaining liquid, called effluent, is pumped
  into a sedimentation tank and allowed to settle.
• Once the effluent has settled, sludge forms at
  the bottom.
• Sludge is treated solid sewage or organic matter
  produced by sewage-treatment plants, paper mills,
  and refineries.
• Sludge is removed and may be incinerated,
  composted, dumped in landfills or oceans, or
  dried and used as a fertilizer.

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25.1 Urban Wastes

• The Worlds oceans are the dumping ground for
  solid wastes, untreated sewage, and sludge.
• Out of sight, out of mind rules this mentality
• Every year thousands of consumer packaging,
  including plastic bottles and containers,
  styrofoam, and plastic film are dumped at sea.
• The Great Pacific Garbage Patch
• The United States has banned dumping of municipal
  waste into the ocean since 1992.

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25.2 Urban Pollution

• Pollution is an unwanted environmental change
  caused by human activity.
• A pollutant is a chemical, or a physical agent,
  that when added to the environment threatens the
  normal functioning of an ecosystem.
• As cities grow and consume more food, water, and
  energy, pollutants are emptied into the
  ecosystem.
• To preserve the Earth, we all must reduce, reuse,
  and recycle.

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25.2 Urban Pollution

• Thermal pollution is waste heat released into the
  environment.
• Waste heat is usually released into bodies of
  water. Water has a high heat capacity.
• Elevated levels of thermal energy reduces the
  amount of dissolved oxygen in these bodies of
  water.
• Marine life die out as the dissolved oxygen
  levels are depleted.
• Thermal pollution also changes the micro-climate
  of the city. Cities are being heated up.

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25.2 Urban Pollution

• Light pollution refers to light from cities that
  interferes with observations of the night sky.
• Light pollution obscures the night sky and
  reduces the effectiveness of optical telescopes.
• Noise is annoying or undesirable sounds.
• Noise pollution disrupts our activities, disturbs
  our sleep, and interferes with concentration.
• Noise levels are measured in units of sound
  called decibels.
• Prolonged exposure to loud sounds can permanently
  damage the middle ear causing hearing loss.

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25.3 Alien Invaders

• Alien organisms, also called exotic species, are
  plants and animals that are introduced into a new
  environment from an outside source.
• Native organisms are the original animal and
  plant inhabitants of an ecosystem.
• All modes of transportation have the capacity of
  moving native organisms out of their natural
  habitat and into new environments.
• Know Table 25-1 page 444 The Impact of Alien
  Species in the United States