Chapter 3

 Matter recycles within and b/w ecosystems  Matter moves through in cycles  Never created or destroyed- just changes form!

 Bound to oxygen, hydrogen and other carbon atoms, carbon forms essential compounds:  carbs, lipids, proteins, and nucleic acids  petroleum, coal and natural gas  atmospheric gases: carbon dioxide and methane

 Photosynthesis- autotrophs take in CO 2 from air & convert it into organic compounds (carbohydrates)  Cellular Respiration & Feeding- consumers feed on plants (taking in organic carbon) and release waste product CO 2 back into air  Plants can then take in that CO 2 again  In oceans- respiration, photosynthesis, and feeding all still occur

 CO 2 in atmosphere dissolves in rain and falls to ground and dissolves into bodies of water  CO 2 returned to atmosphere at surface of ocean as a gas due to circulation of water

 Decomposition- Organisms die  decomposers (bacteria) feed on dead organic matter breaking it down into its simplest components  CO 2 is released into soil pores which eventually diffuse into the atmosphere  Deposition- Organic C embedded in layers of mud  pressure & heat compress them for millions of years  sedimentary rocks (shale)  If dead plant matter builds faster that it can decay  layers of organic C become fossil fuels (coal, oil, natural gas) instead of sedimentary rock

 In ocean and on land- animals combine C with Ca and O to form calcium carbonate (CaCO 3 ), forms skeleton (insects, crustaceans, shells, corals, some plankton)  These organisms die, sink to bottom and over time sediment and shells cement together forming rock  decomposition  deposition

 Combustion- Humans dig up fossil fuels  burn  CO 2 into air  Deforestation- Burning of forests releases CO 2 into air

 Geological activity- turns carbon in marine sediment into carbonic rock  Volcanic Activity- carbonic rock melts, releases CO 2 during eruption  Volcanoes, hot springs and geysers- spew CO 2 and methane (CH 4 )back into the atmosphere.  (Volcanoes release mill metric tons CO 2 /yr; vs. humans 30 billion via combustion)  Weathering and Erosion wash carbon compounds from rock in the Earth’s crust into the ocean

 “Release of CO 2 from soils has global implications because it occurs in ecosystems worldwide and its magnitude is such that it contributes significantly to the greenhouse effect. The greenhouse effect is a natural property of our atmosphere in which greenhouse gases prevent the transfer of heat from the earth’s surface to outer space, thereby warming the atmosphere. Since the industrial revolution human activity (e.g., fossil fuel combustion and deforestation) has led to global increases in the concentrations of greenhouse gases (such as CO 2 ) in our atmosphere. This rapid increase will likely lead to a cascade of environmental impacts such as global warming, sea level rise, alteration of precipitation patterns, and increased storm severity (IPCC 2007).”  /description.html /description.html

Forms of Nitrogen:  N 2 (gas) makes up about 80% of the atmosphere, most abundant form  NH 3 (ammonia)  NO 2 - (nitrite)  NO 3 - (nitrate)  Organic Nitrogen- a nitrogen compound that had its origin in living material (amino acids of proteins, urea (a product of protein digestion), nucleic acids, chlorophyll)  Dissolved N 2 in ocean & large bodies water  Problem: most organisms (consumers) cannot utilize N in N 2 form, only certain bacteria can use it in this form

 Nitrogen fixation- conversion of atmospheric nitrogen (N 2 ) into ammonia (NH 3 ) and nitrate (NO 3 - )  Requires a lot of energy to break bonds between two N atoms  Two ways bonds are broken:  1. Abiotic Fixation  2. Biological Fixation

 Lightning- causes N 2 to combine w/ O 2 producing NO 3 - which is carried to land via rainfall  Accounts for 10% of nitrate entering cycle

 Symbiotic bacteria found on roots of legumes (in nodules) convert N 2 into NH 3 (ammonia)  Legumes include clovers, alfalfa, soy beans, chic peas  Returns excess N to soil that it is not using for other producers to uptake via roots

 One group of bacteria convert ammonia (NH 3 ) into nitrites (NO 2 - )  Then another group converts nitrites (NO 2 - ) to nitrates (NO 3 - ) which is form most useable by plants

 Assimilation- formation of organic N compounds from inorganic N compounds  Plants convert nitrates and ammonia into organic nitrogen (proteins, nucleic acids, chlorophyll)  Consumers obtain organic nitrogen by consumption of plants and other organisms

 Decomposing microorganisms (bacteria, fungi) break down organic matter in animal waste and dead plants and animals  Convert organic N into ammonia (NH 3 ) that plants can absorb

 Bacteria called anaerobes (live in anaerobic environments) convert nitrates (NO 3 - ) to N 2 and release back into atmosphere

 Humans   Manufacturing and use of fertilizers from N 2  uptake by producers or runoff into water  When fossil fuels are burned they release large amounts of nitrogen oxides into the air  comes down as acid rain