ES 1.7: Cycles in the Ecosystem. Nature Recycles

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1 ES 1.7: Cycles in the Ecosystem Nature Recycles Law of Conservation of Mass: states that mass is neither created nor destroyed in any ordinary chemical reaction In a natural ecosystem, most mass/matter is recycled through various chemical reactions bio geochemical cycles: the flow of chemicals between the environment and the organisms within Brewer 1

2 ES 1.7: Cycles in the Ecosystem The Carbon Oxygen Cycle Recall that plants use carbon dioxide in the process of photosynthesis organic compounds: the products of photosynthesis, such a sugars and the respective proteins, oils, and starches produced cellular respiration: organic compounds are broken down in the presence of oxygen, producing carbon dioxide. Carbon Oxygen cycle is out of balance more carbon dioxide is being produced than is being converted by photosynthesis combustion: a chemical reaction were organic compounds are burned. Recall the general equation: fuel + oxygen = carbon dioxide + water Brewer 2

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4 ES 1.7: Cycles in the Ecosystem The Carbon Oxygen Cycle Fossil fuels account for the vast majority of additional carbon dioxide in the atmosphere Coal, oil, natural gas, etc... Brewer 4

5 ES 1.7: Cycles in the Ecosystem The Nitrogen Cycle Plants and animals need nitrogen to make protein The atmosphere is 78% N 2, but cannot be used by plants and animals Bacteria known as "nitrogen fixers" are responsible for making N 2 available to living things nitrogen fixers: bacteria that convert N 2 gas into nitrate or ammonium ions (fertilizers) that plants can use nodules: places where nitrogen fixing bacteria live on legumes, a family of plants including peas, beans, alfalfa, clover, etc... Plants provide food for the bacteria; in return the bacteria provide usable nitrogen to the plant Brewer 5

6 ES 1.7: Cycles in the Ecosystem The Nitrogen Cycle Animals get nitrogen from plants or other plant eating animals in the form of protein. Unused nitrogen compounds are broken down by bacteria back into nitrogen gas a released into the atmosphere Lightning plays a small role in fixing nitrogen. Lightning strikes can chemically combine nitrogen and oxygen gas in the atmosphere which can be converted by bacteria into nitrate fertilizer Humans manufacture large amounts of commercial fertilizers to grow crops. Nitrogen from the air is combined with hydrogen from natural gas under high pressure and temperatures to produce fertilizer Nitrogen compounds can also be produced from the burning of fossil fuels. Brewer 6

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8 ES 1.7: Cycles in the Ecosystem The Mineral Cycle most minerals (ex. Ca and P) are stored in rocks weathering: the process of physical and chemical forces that release minerals from rocks wind, water, and plants can all be responsible for weathering Chemical weathering (acid rain) dissolves minerals Roots produce chemicals that dissolve minerals in rocks leaching: minerals carried away by water moving through the soil mining: the process of removing a natural substance from an ecosystem faster than it is replaced erosion: mineral particles removed from an ecosystem by the action of wind and water. Whether by leaching, mining, or erosion, minerals are removed from an ecosystem and no longer made available for living things Brewer 8

9 Environmental Science weathering of granite by wind Brewer 9

10 Environmental Science open pit coal mining Brewer 10

11 erosion by water Brewer 11

12 ES 1.7: Cycles in the Ecosystem The Hydrologic Cycle Hydro: prefix meaning water the total amount of water on the planet remains relatively constant Water enters the atmosphere through evaporation and transpiration Evaporation: energy from the sun heats water, changing it from its liquid state into its gaseous state water vapor Water is taken up by plants from roots and travels to leaves Small openings on the leaf called stomata release the water vapor through the process of transpiration over 500,000 gallons of water may enter the atmosphere through transpiration from only 1 acre of corn Brewer 12

13 ES 1.7: Cycles in the Ecosystem The Hydrologic Cycle condensation nuclei: particles of dust in the atmosphere form the beginnings of condensation of water vapor. Once the water droplets become to heavy they fall from the sky as precipitation, which includes all forms of falling moisture from the atmosphere runoff: water that flows over land from precipitation. Runoff eventually finds its way to larger and larger bodies of water, where it may eventually arrive at the ocean. infiltration: the process of precipitation entering the ground percolation: the trickling of water through various layers of soil and ground, ending at a layer of impermeable rock. This layer is called groundwater. aquifer: the layer of porous rock where groundwater is stored Seepage: the natural flow of groundwater at a spring More often groundwater is pumped up to the surface from a well drilled into the aquifer. Brewer 13

14 condensation nuclei Brewer 14

15 satellite image of cloud condensation Brewer 15

16 runoff from field Brewer 16

17 aquifer Brewer 17