Review – Cycles, tectonic boundaries, and environmental laws.
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Transcript of Review – Cycles, tectonic boundaries, and environmental laws.
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.
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 _____________
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