CYCLING OF MATTER

Biogeochemical Cycles

• (nutrient cycles) nutrients, atoms, ions, and molecules that organisms need to live, grow, and reproduce are continuously cycled from the abiotic environment to the biotic environment

• Some of the carbon atoms of your skin may have once been dinosaur skin

Hydrologic Cycle (water cycle)

Hydrologic Cycle (water cycle)• Evaporation-conversion of liquid water to water

vapor• Transpiration-evaporation of water from leaves of

trees that pull water up through the roots/stems• Condensation-water vapor to liquid water• Precipitation-hail, sleet, rain, snow• Infiltration-movement of water into soil• Percolation- downward flow of water through

permeable soil and rock to groundwater• Runoff-movement of water downslope back to the

sea

Hydrologic Cycle

• Benefits: water dissolves many nutrients so it is a major medium for transporting nutrients within and between ecosystems– Evaporation removes impurities dissolved in

water– Water that percolates through the soil is

naturally filtered and purified by chemical and biological processes

Hydrologic Cycle

• How do humans affect the water cycle?– Depleting groundwater supply– Clearing of vegetation increases runoff,

reduces infiltration that recharges groundwater supplies, increases flood risk, accelerates soil erosion and landslides

– Polluting water supply with fertilizer runoff, etc.

Carbon Cycle

• From abiotic environment to biotic– Photosynthesis; plants “fix” atmospheric

carbon into molecules of glucose

Carbon Cycle

• From the biotic to abiotic – Aerobic respiration– Burning of fossil fuels

Carbon Cycle

• Largest carbon stores:ocean sediments

• How humans affect carbon cycle:– Deforestation (less carbon removed from the

atmosphere)– Adding large amounts into atmosphere

through the burning of fossil fuels

Nitrogen Cycle

• Nitrogen is most abundant element in atmosphere (78%), but cannot be absorbed and used directly by multicellular plants or animals

• Can be “fixed” both by lightning and bacteria

Nitrogen Cycle

• Nitrogen fixation: specialized bacteria (symbiotic with legumes; exs. Alfalfa, soybeans) convert nitrogen gas to ammonia

Nitrogen Cycle

• Nitrification: 2 step process in which ammonia in soil is converted to nitrate ions by bacteria (easily taken up by plants)

Nitrogen Cycle

• Assimilation: plants make nitrogen part of its tissue, then animals that eat the plants also make the nitrogen part of its tissue

Nitrogen Cycle

• Ammonification: specialized decomposer bacteria convert nitrogenous wastes back to ammonia

Nitrogen Cycle

• Denitrification: specialized anaerobic bacteria convert ammonia, nitrates, nitrites back to nitrogen gas

Nitrogen Cycle

• How humans affect the nitrogen cycle:– Adding nitric acid by burning fuels which

causes acid rain– Adding nitrous oxide to the atmosphere which

contributes to greenhouse effect and ozone depletion

– Excess nitrogen to water systems disrupts ecosystems

Other Cycles

• Sulfur

• Phosphorous– Not found in large amounts in the atmosphere

so enters through weathering of rocks

• MATTER CYCLES ENERGY DOES NOT!