Review – Cycles, tectonic boundaries, and environmental laws

Cycles

• One-way of energy

• Cycling of matter

The Nitrogen Cycle

• 78% of the troposphere is composed of nitrogen gas.

• Nitrogen is an important element for the making of proteins, nucleic acids, and vitamins.

The Nitrogen Cycle

Processes convert nitrogen gas into compounds that can be used in the food webs:

– Atmospheric electrical discharge makes nitrogen and oxygen gases react to form nitrogen oxide.

– Specialized bacteria fix nitrogen gas into ammonia to be used by plants (nitrogen fixation).

– Ammonia not used by plants may go through nitrification to form nitrite ions (toxic to plants) and nitrate ions (easily taken up by plants).

After nitrogen fixation and nitrification…

• Plant roots absorb these dissolved substances called assimilation and use them to form DNA and proteins. Animals consume nitrogen through plants or plant-eating animals.

• In ammonification, decomposer bacteria convert waste into simpler nitrogen-containing compounds such as ammonia and water-soluble salts containing ammonium ions.

• Nitrogen returns to the atmosphere through denitrification by converting ammonia and ammonium ions into nitrite and nitrate ions and then into nitrogen gas and nitrous oxide gas.

• This begins the cycle again.

How do we impact the nitrogen cycle?

• Adding nitric oxide (NO) which can convert to nitrogen dioxide gas (NO2) and nitric acid (HNO3) causes ___________

• Adding nitrous oxide (N2O) through anaerobic bacteria and inorganic fertilizer causes _________

• Adding nitrates to aquatic ecosystems causes _____________

The Carbon Cycle

• Cycle is based on carbon dioxide gas.• Key component of nature’s thermostat.

The Carbon Cycle

How do we impact the carbon cycle?

Describe the internal processes that drive plate tectonics.

Compare and contrast the different plate boundaries.

Environmental Laws• Clean Air Act (1970, 1977, 1990)

– Regulates air emissions from area, stationary, and mobile sources– Established National Ambient Air Quality Standards

• Clean Water Act– Sets wastewater industry standards– Set water quality standards for all contaminants in surface water– Made clear it’s unlawful to discharge pollutants from point source

• Endangered Species Act– Maintains list of endangered and threatened species to prohibit

the taking of a listed species or adversely affect habitat

Environmental Laws• Federal Insecticide, Fungicide, and Rodenticide Act

– Controls pesticide distribution, sale and use– Gives EPA authority to study usage– Forces user to register

• Oil Pollution Act of 1990– Strengthens EPA’s ability to prevent and respond to catastrophic oil

spills– Makes funds available for cleanup through a trust fund financed by

taxes• Pollution Prevention Act

– Reduces amount of pollution through cost-effectives changes in production, operation, and raw material use

Environmental Laws

• Toxic Substances Control Act– Tracks the 75,000 chemicals currently produced or

imported into the United States• Food Quality Protection Act– Requires a safety standard-reasonable certain of

no harm that must be applied to all pesticides used on food