Human impacts on the environment

SC.912.L.17.16

Impact of Human ActivitiesDeforestation is the permanent destruction of indigenous forests and woodlands (biosphere).

Often the land is cleared for conversion into agricultural land to feed growing numbers of people, cattle ranching, or to obtain firewood or building materials.

Forests and woodlands act as major carbon stores. Removing these stores means that carbon dioxide levels in the atmosphere will climb. Trees also help to circulate water in the local ecosystem (hydrosphere), removing them leads to the possibility of a drier climate.

Impact of Human ActivitiesAir pollution (atmosphere) comes from a number of sources. These include industrial sites, home heating, transportation vehicles, and even outdoor burning.

Human activities can release substances into the air, some of which cause problems for humans, plants, and animals.

People (biosphere) with health problems such as asthma, heart, and lung disease may also suffer more when the air is polluted.

Impact of Human ActivitiesCoral reefs are stony structures built by a symbiotic relationship between coral, an animal (biosphere), and single-celled algae -- a plant (biosphere). The coral houses the algae, which use photosynthesis to make sugar that helps feed the coral. The coral's waste products, including nitrogen and phosphorus compounds, fertilize the algae. Live coral polyps grow on the dead bodies of their ancestors, allowing coral to build up to tremendous depths if left alone.

Coral reef destruction can occur when seawater (hydrosphere) warms up. The coral expels the algae, losing its major source of food. The algae give the reefs its color, so “bleaching” occurs. Overfertilization is another problem.

Impact of Human ActivitiesThe ozone layer (located in the stratosphere) is made up of molecules containing three oxygen atoms (O3). Even though ozone only exists in about 3 molecules out of every 10 million air molecules, it plays an important role. Ozone absorbs a portion of the ultraviolet (some UV-B and all UV-C rays) radiation that is sent from the sun. The UV-B light that is absorbed has been linked to many harmful effects (such as certain types of skin cancer, cataracts, and harming crops and certain types of marine life).

Ozone concentrations vary naturally with sunspots, seasons, and latitude. However, human activities have been linked to a depletion of our ozone shield well beyond changes due to natural processes.

Impact of Human ActivitiesHumans have released chlorofluorocarbons (CFCs), halons, and methyl bromides into the atmosphere causing ozone depletion by breaking up O3 molecules.

CFCs have been used in many applications, including refrigeration, air conditioning, aerosol propellant, and cleaners for metals and electronic components.

Halons are used to extinguish fires where large computers, military hardware, and commercial aircraft engines are found.

Methyl bromides are used in agricultural fumigants.

The use of CFCs has been greatly reduced thanks to international agreements on production and consumption of halogen-containing gases.

Now let’s watch the production of a consumer product

…and the waste it creates

Resources

Corn flakes require farmers to grow corn. The growing of the corn will require the farmer to prepare the soil and plant the seeds. As the corn grows it will require fertilizer and lots of water. Eventually, the corn will have to be harvested.

Production

Once the corn is brought into the factory, it must be dried, baked, and turned into flakes.

Of course, additional energy must be used during these steps to transform the corn.

Packaging

Once the corn flakes have been prepared, they must be packaged for the consumer to buy. Packaging today includes an inner bag which contains the corn flakes, and a cardboard box (now 100% recycled paperboard).

Transportation

Transportation occurs in two separate parts of the corn flakes product cycle. First, the corn must be transported from the farm area to the cereal factory. Second, the finished corn flakes must be transported to the local supermarkets for sale to the public. Third, you and I transport the corn flakes home.

Disposal

Once we are finished eating up our box of corn flakes, we have two parts that need to be disposed of.

The inner bag the contained the corn flakes gets thrown out with the trash. This part will eventually end up in the local landfill.

The outer box can be recycled. It can be separated out from the other trash and sent to a recycling center for processing.

PollutionOn the farm, pollution may occur when fertilizers are washed away.

Farm equipment (during planting and harvest) as well as the trucks that transport the corn all contribute to air pollution.

The cereal factory itself may produce some pollution as well as the transportation to get the corn flakes to the supermarket.

If we drive to the supermarket, our vehicle creates some air pollution also.

Impact of Human Activities

Think of all the materials that go into the building of a single automobile. Millions of automobiles are produced each year all around the world. Once an automobile is built it must be transported to a dealer where you can buy it.

Eventually your new car will be an old car that no one wants to own.

Impact of Human Activities

Eventually your one-time new car will end up in an automotive junk yard or salvage yard. Many car components, including tires, may end up piled up someplace, or even squeezed down to a rough pile of scrap metal.

More materials are being recycled, but some may still cause pollution problems. Old used oil and other automotive fluids may leak into the ground, batteries may leak, tires might catch fire and pollute the air.

A variety of hazards must be monitored for each car left sitting in the junk yard or salvage yard.