ENVIRONMENTAL SCIENCEChapter 25 Human Society and the Biosphere

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, men’s razors

Some manufacturing companies use planned obsolescence to maximize their profit potential in a marketplace.

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.

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).

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.

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.

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.

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.

25.1 URBAN WASTES

The World’s 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.

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.

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.

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.

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