Cycling of Matter 4.3

“biogeochemical” cycles

1. WATER2. CARBON-OXYGEN3. NITROGEN4. PHOSPHORUS

WATER (H20) CYCLE

• The continual movement of H20 from the Earth’s surface and oceans to the atmosphere and back to the surface and oceans again.

• Powered by the sun (solar energy) which causes evaporation & transpiration (water loss from plants).

• Cells: 70-90% water…Earth: 75% water

…water is a KEY factor in terrestrial ecosystems!!

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• precipitation (forms: rain, snow, sleet, hail, fog)

• transpiration (aka evapotranspiration)

• evaporation

• runoff

• water vapor• percolation (water into soil)

• ground water (water in soil)

CARBON (C) CYCLE• CO2 to plants photosynthesis (requires

sunlight and H20 too!) carbohydrates

carbohydrates consumers (AND PLANTS!) respiration

respirationback to CO2 and biomass.

• PHOTOSYNTHESIS stores solar energy in the form of C-C bonds in organic compounds (glucose!).

• RESPIRATION releases chemical bond energy and makes it available (“usable”) to cells…cells need energy to grow, develop, reproduce, respond, maintain homeostasis, etc.

• Sources: all organisms (including decomposers), natural burning, power plant / factory / vehicle emissions.

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– Photosynthesis– Cellular respiration (CR)– Decomposition (CR): bacteria & fungi in soil– Combustion– Food chain (consumers…part of CR)– CO2 , O2, H20, Sun

NITROGEN (N) CYCLE• Air contains ~78% N2 gas• N2 gas must be converted into other

compounds (nitrates) before it can be used by plants called nitrogen fixation (done by bacteria) then by other living things.

• Plants use the nitrogen compounds they absorb through their roots (a process called assimilation) to make amino acids, proteins, and other important substances. Animals get the nitrogen they need by consuming plants or organisms that consume plants.

Others!

• Decomposers play an important role by breaking down N-containing animal wastes and the remains of dead organisms similar process to nitrification.

• Another type of bacteria converts some of the ammonia and nitrates into free N2 gas back into atmosphere…this is called denitrification.

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• Ammonia• N2 (nitrogen gas), H20• Nitrogen fixation• Denitrification• Nitrogen-fixing bacteria• Nitrates• Assimilation (occurs through plant roots)• Denitrifying bacteria• Decomposers• Death/waste

PHOSPHORUS (P) CYCLE

• P is a component of ATP (energy storing compound used by cells)

• and is a component of DNA (genetic code)• Found in soil and rock as calcium

phosphate which dissolves in H20 to form phosphate plants absorb through their roots animals eat plants (P is transferred) animals and plants die phosphorus is returned to soil.

http://www.marietta.edu/~biol/102/ecosystem.html#top

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• FoldNotes…RED ARROWS

• Key words on previous slide.