Environmental Cycles The Movement of Matter and Energy Through the World

What Makes up a Cycle ? Materials are found in different forms or places (reservoirs). Materials move from one reservoir to another (flux). Cycles are made up of the flux of materials through different reservoirs and back.

What Makes up a Cycle ? Cycles are made up of the flux of materials through different reservoirs and back. The size of each reservoir and the rate of flux between them defines how the cycle works. Cycles are driven by energy.

The Nitrogen Cycle Reservoirs –Atmospheric Nitrogen –Ammonia –Organic Nitrogen –Nitrite –Nitrate –Nitrous Oxide Fluxes Energy

The Nitrogen Cycle

Fluxes –Nitrogen fixation Lightning Biological Industrial (Haber-Bosch) –Assimilation –Decomposition –Nitrification –Denitrification Energy

The Nitrogen Cycle

Energy –Nitrogen fixation requires a high input of energy. Electricity (lightning) Solar energy (biological) Petroleum (industrial) –Nitrification and Denitrification are ways that bacteria harvest energy.

Human Impacts on the Nitrogen Cycle Industrial nitrogen fixation Intensive agriculture (Feedlots and Rice Paddies)

Human Impacts on the Nitrogen Cycle Industrial nitrogen fixation –Doubled the rate of fixation –Depleted soils of other nutrients –Reduced biological diversity –Increased concentration of nitrous oxide in the atmosphere Intensive agriculture (Feedlots and Rice paddies) –Anaerobic bacteria convert more of the nitrogen into nitrous oxide

Increase in Fertilizer Use

Consequence of Excess Nitrate

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The Carbon Cycle Reservoirs –Atmospheric carbon dioxide –Oceanic –Biotic carbon –Soils and Sediments –Fossil fuels (coal, oil and gas) –Sedimentary rock Fluxes Energy

The Carbon Cycle

Fluxes –Photosynthesis and Chemosynthesis –Respiration (Consumption and Decomposition) –Sedimentation –Uplift and Erosion –Dissolution Energy

The Carbon Cycle

Energy –Solar energy (photosynthesis) –Chemical energy (chemosynthesis) –Consumers and decomposers get their energy by oxidizing organic carbon (respiration)

Human Impacts on the Carbon Cycle Burning Fossil Fuels Deforestation Industrial nitrogen fixation

Human Impacts on the Carbon Cycle Burning Fossil Fuels –Moves carbon out of a stable reservoir and into the atmosphere Deforestation –Decreases the amount of carbon pulled out of the atmosphere Industrial nitrogen fixation –Increases photosynthesis and pulls carbon out of the atmosphere

The Phosphorus Cycle Reservoirs –Minerals –Dissolved –Organic molecules DNA and RNA ATP Fluxes Energy

The Phosphorus Cycle

Fluxes –Geological uplift –Weathering and Erosion –Incorporation into organic molecules –Decomposition –Precipitation Energy

The Phosphorus Cycle

Energy –Plate tectonics (uplift of minerals) –Climatological energy (erosion) –Organisms expend energy from respiration to take up phosphorus

Human Impacts on the Phosphorus Cycle Mining phosphate minerals –Increases the amount of phosphorus entering the biosphere –Because phosphorus is often limiting, excess phosphorous can lead to eutrophication in the same way that excess nitrogen does

The Gaia Hypothesis Proposes that the entire biosphere acts as a self-regulating system. Developed by James Lovelock in the 1970’s. Conditions that are favorable for life are maintained by the action of living things.

Biosphere 2 An experiment to try to reconstruct the important cycles and systems that help to maintain life on earth.