science biology (3).docx

***[Cycling of Matter in Ecosystems:]*** ***[Introduction:]* Planet Earth is the ultimate recycler. All particles in all organisms are part of a** **biogeochemical cycle. There are three major cycles of matter, called biogeochemical cycles:** **➜Water** **➜Carbon** **➜Nitrogen** ***[Human acti...

***[Cycling of Matter in Ecosystems:]*** ***[Introduction:]* Planet Earth is the ultimate recycler. All particles in all organisms are part of a** **biogeochemical cycle. There are three major cycles of matter, called biogeochemical cycles:** **➜Water** **➜Carbon** **➜Nitrogen** ***[Human activities that impact the water cycle:]*** **➜Damming rivers** **➜Polluting waterway** **➜Draining swamps\ ➜Irrigation** **Carbon is a component of all living things. It moves between the biotic and the abiotic world, mostly between atmospheric or dissolved CO2 and photosynthesizing organisms.** **Most of Earth's carbon is stored in:** **➜Fossil Fuels** **➜Plants** **➜Plants** **➜Oceans** **➜Limestones** ***[2 major human impacts on the carbon cycle]*** **➜Fossil fuel combustion releases huge** **quantities of stored carbon into the** **atmosphere in the form of carbon dioxide** **➜*Major combustion sources are vehicle and factories*** **➜D*eforestation is also a major contributor to atmospheric CO2 levels*** ***[4 major problems with excess co2 (carbon dioxide)]*** **➜CO2 is a greenhouse gas and is causing climate change** **➜Warming of ocean waters** **➜melting of icecaps** **➜Disruption of ecosystems everywhere**  **Nitrogen Cycle:** **➜Although abundant in the atmosphere, N2** **is not easily attained from the abiotic** **Environment** **➜Most nitrogen used by living organism is** **taken from the atmosphere and 'fixed' by** **special soil bacteria. Nitrogen fixation by** **bacteria convert the nitrogen into usable** **forms like nitrates, nitrites and ammonia.** **➜Lighting and UV light also fix small** **amounts of nitrogen** **Where does the nitrogen come from?** **➜Atmosphere, Human made (fertilizers), Animals(urine), Decomposers (feed on dead organisms, releasing nitrogen), Denitrification (denitrifying bacteria will release nitrogen gas back into the atmosphere).** **3 major human impacts on** **the nitrogen cycle** **➜Vehicle exhaust adds nitrous oxide to** **the atmosphere, contributing to acid** **Rain.** **➜Artificial fertilizers add excess nitrogen** **to soil, changing its acid level** **➜Huge feedlots cause excess nitrogen** **run-off into water, leading to the rapid** **growth of algae**