Biogeochemical Cycles• A biogeochemical cycle is how animals obtain

useful inorganic and organic materials, use them, and return them to be recycled.

Water Cycle• As you can see from the above image there are many paths for the water cycle. Here is one scenario.– The sun heats up a body of water

causing evaporation – The water vapor rises into the

atmosphere and condenses as it cools forming clouds

– When the water content in the clouds exceeds the capacity to hold the water precipitation (rain) begins

• Scenario 2– Water from precipitation or bodies

of water seep into the ground where it is used by plants (percolation)

– The plants continually release water through their leaves through a process know as transpiration or evapotranspiration

– The rest is the same as scenario 1

Carbon Cycle• The carbon cycle is considered to b a

biogeochemical cycle. Bio because of the sugars and molecules that are made from it and geo from the CO2 that is produced as a result of cellular respiration and the burning of organic compounds. Carbon is the building block of life.

• Uptake of Atmospheric CO2

– Primarily removed by plants, algae, phytoplankton, and phytobacteria via the process of photosynthesis

– Additional amounts of CO2 are dissolved in large bodies of water (oceans)

– A small amount combines with water vapor to become acid rain

• Release of CO2 to environment– Nearly all living things produce CO2

– Decaying organisms will release CO2 – The combustion of organic materials

releases large amounts of CO2 – The eruption of volcanoes is another

source contributing to atmospheric CO2

Nitrogen Cycle• Nitrogen is an important

building block used in the formation of DNA and proteins. Nitrogen is contained in the waste of every living organism as well as in the decaying organic material plants and animals. – Nitrogen uptake is primarily via

ingestion. – Nitrogen is returned to plants

through the process of nitrogen fixation that is performed by bacteria involved in the breakdown of dead organic material.• Nitrate fixed by bacteria is the

primary source of nitrogen available to plants

• Phosphorus cycle works in much the same way

Human impact on the environment• As an industrialized nation we are constantly forced to weigh the effects

of manufacturing versus the benefits of the products. Pollution is a term given to a harmful (gas or particulate) substance that is released into the environment. Although some pollution occurs naturally (volcanoes) most pollutants are produced as a result of industry.– There are several different classifications:

• irritant - causing inflammation and discomfort • teratogen - causing birth defects • carcinogen - causing cancers

Clean Air Act• Proliferation of pollutants depletes our ozone layer, contributes to increased

global warming, increases the amount of acid rain, and puts people at risk for health problems. In 1970 the Clean Air Act sought to address 6 of the worst known pollutants. The EPA (Environmental Protection Agency) monitors these pollutants and sets acceptable levels for their release.– CO - Carbon monoxide – NO2 - Nitrogen dioxide – SO2 - Sulfur dioxide – Particulate pollutant – Pb - lead – O3 - ozone

Smog• Smog is a term used to describe a collection of pollution that is

condensed in a particular area.– generally a brownish color – mostly formed from the burning of fossil fuels – rich in NO2, SO2 andCO2 – creates surface ozone – creates a temperature inversion (top layer warmer than the lower layer)

which aids in the trapping of more smog at increasingly lower levelsValues Air QualityDescriptor 0.0 to 0.064 0 to 50 Good 0.065 to 0.084 51 to 100 Moderate 0.085 to 0.104 101 to 150 Unhealthy forSensitive Groups 0.105 to 0.124 151 to 200 Unhealthy 0.125 (8-hr.) to 0.404 (1-hr.) 201 to 300 Very Unhealthy http://www.vcapcd.org/forecast/fcst.htm

Acid Rain• Acid rain is created as CO2, NO2 and SO2 mix with water in the

atmosphere to create weak acids that return to the Earth's surface as rain. This rain accumulates in the water table and in the fresh water systems where it becomes concentrated killing wildlife, vegetation, and bacteria.

Ozone Depletion

• Ozone depletion is perhaps the most overlooked environmental hazard. Although the banning of CFCs in the1970s helped slow the thinning of this layer, the depletion continues today. Effects of thinning are:– increased skin cancers – premature aging – plant damage – reduction in the amount of phytoplankton in the oceans

Global Warming• Although global warming is vital to the survival of the planet, its rate of increase

threatens life. Most scientists will conclude that global warming is a natural process that has cycles of increase and decrease but there are undeniable contributions that we are making that have significantly sped up the process of warming.– Burning of fossil fuels - releases CO2 – Global deforestation - increases CO2 levels – These activities have led to the following consequences:– Rising sea levels – Increased frequency of damaging storms - hurricanes and tornados – Increased frequency of severe weather - heat waves and droughts – Relocation of global crop growing areas