Chapter 25: Cycling Carbon
Terms in this set (12)
What is the significance of the carbon cycle to all life on earth?
Carbon is integral throughout the biodiversity of life throughout the biosphere
Explain the short-term carbon cycle - photosynthesis and respiration.
Photosynthesis: Take in CO2 and H2O and you produce C6H12O6 and O2. Photoautotrophs are producing their own carbon energy source using sunlight and fix carbon (From inorganic form to organic form)
Respiration: Take in C6H12O6 and O2 and produce CO2, H2O and ATP
-Heterotrophs use this
You get C6H12O6 through the cycling of the food web through trophic levels
Decomposers return carbon and nutrients to the soil and atmosphere which then go back into producers
How do photosynthesis and respiration affect atmospheric CO2 concentrations?
Photosynthesis levels are seasonal and respiration is constant. More plants in the Northern Hemisphere than in the Southern...The seasons of spring and summer in the north experience lower levels of CO2. High [ ] at end of winter and the beginning of spring...as we move through summer, CO2 [ ] decreases
How do we determine recent and historical atmospheric CO2 concentrations, and what is the relationship between these concentrations and temperature?
Ice cores can tell us about historic CO2 levels by measuring the air bubbles trapped within. Concentration will be higher at warm interglacial periods and low [ ] at colder glacial periods.
You can measure it more directly from observatories that are isolated (ex: Mauna Loa observatory)
What are the major sources and sinks of CO2?
Sources: Biological input (respiration), mid-ocean ridges, volcanoes, human activities (fossil fuel burning), and deforestation
Sinks: Ocean, land, and atmospheric CO2. Biological (photosynthesis), geological: chemical weathering of rocks...CO2 in atmosphere produces acid rain that weathers sedimentary rocks and removes carbon from them. This carbon gets deposited in oceans into bicarbonate or just CO2. Organisms use the bicarbonate to produce shell structures.
How does carbon cycle through the earth? What are the major reservoirs and fluxes of carbon?
Major reservoirs (in order from greatest to least): sedimentary rock is the largest, ocean, soil, atmosphere, organisms.
Fluxes: Rate at which carbon flows from one reservoir to another.
-Photosynthesis (CO2 from atmosphere transferred to plants)
-Plant respiration (CO2 from plant to atmosphere)
-Litterfall (Carbon from plant parts, branches, leaves, etc. fall back to the Earth and return carbon to soil)
-Soil respiration (decomposition releases CO2 to be released to atmosphere)
-Ocean (carbon is absorbed at released at the Earth's surface
Why are shell-building animals and corals considered a sink of carbon?
Organisms use bicarbonate (by consuming CO2 in the ocean) to produce calcium carbonate (CaCO3) structures which are the shells and coral skeletons. To make calcium carbonate, shell-building marine animals such as corals and oysters combine a calcium ion (Ca+2) with carbonate (CO3-2) from surrounding seawater, releasing carbon dioxide and water in the process called biominerlization
What are the geological processes involved in the cycling of carbon?
Plate tectonics: New crust forms at spreading centers, the places where molten rock ascends from the mantle. Old crust is destroyed in subduction zones, where one slab of crust slides beneath another, returning material to the mantle. Plate tectonics form mountains and ocean basins, and it plays an important role in the long-term carbon cycle. The crust that descends into subduction zones carries with it sediments, including carbonate minerals and sedimentary organic matter. Subduction removes carbon from Earth's surface, but this carbon will be recycled to the surface as carbon dioxide emitted from volcanoes and mid-ocean ridges.
Seafloor spreading and volcanism( releasing ash, carbon, and CO2) brings carbon up from the mantle as well, providing a carbon source.
Chemical Weathering: CO2 is removed from the atmosphere when rain washes atmospheric carbon dioxide down to the soil and the sea. CO2 in the soil exists as carbonic acid, which combines with minerals in the soil to form carbonates - a process known as weathering.
What roles do humans play in the carbon cycle?
Humans burn fossil fuels, serving as 80% of all human carbon contributions. Deforestation for the purpose of agriculture produces CO2 as well. Through respiration, we inhale oxygen and exhale CO2.
How does carbon cycle through a community?
How much energy moves on to the next tropic level? How does this affect biomass of the next level?
90% of transferred energy is essentially "lost." Because energy is lost at each step of the trophic pyramid, biomass present at one level is only 10-15% of the level below.
What changes occurred in oxygen levels on earth over time?
Once photosynthesis started, you start seeing a build up of oxygen because the carbon thats made within photosynthesis is getting stored in sediments and soils and this means oxygen production isn't all consumed by respiration, therefore it facilitates and increase in O2 levels.
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