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1.b. The carbon and water cycles are systems with inputs, outputs and…
1.b. The carbon and water cycles are systems with inputs, outputs and stores
Water
Stores
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Snow/ice e.g. ice-caps, ice sheets and glaciers(2%) and 75% of fresh water in cryosphere
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Soils, flora, fauna, humans and atmosphere(rest %)
Inputs and outputs
Evaporation and Transpiration: water evaporates from surface water and from surfaces on land, natural and human-made. Plants transpire water through leaves. Term evapotranspiration is used to describe these two processes transferring water into atmosphere
Condensation, precipitation, ablation and sublimation: water vapour in atmosphere becomes liquid due to condensation. Water tranfered to surfac through precipitation. Ablation = water lost from snow and ice(eg melting, calving icebergs or evaporation). Sublimation = solid state -> gaseous
Runoff and infiltration: water on surface drains(runoff) and collects in streams and rivers with most rivers flowing into oceans. Most precipitation ends up as runoff after infiltration, and flowing through soil
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Carbon
Global
Sedimentary rocks such as limestone for 240-300 million years(100,000,000 billion tonnes)
Carbon in atmosphere, oceans, soil and biosphere circulates relatively rapidly
Oceans for 25-1250 years(39,000 billion tonnes)
Fossil fuels(4,000 billion tonnes)
Soils and peat(1,500 billion tonnes)
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Slow
Marine organisms such as coral, shellfish and phytoplankton combine carbon with calcium to build their shells and skeletons from calcium carbonate. When they die they sink to the ocean floor and over millions of years, heat and pressure convert these deposts to carbon-rich sedimentary rock
Typically the carbon is stored for 150 million years/ Some rock is melted at plate boundaries releasing carbon to atmosphere as C02(eruptions). Rock near surface is weathered and C02 is released. carbon can be carried away in dissolved forms by streams an rivers leading to the ocean
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Fast
Carbon storage in atmosphere, plants, soil and peat is small but crucial to the carbon cycle
Transfers between the atmosphere, oceans, living organisms and soil are some ten to one thousand times faster than in the slow. Key components = land plants + phytoplankton
Phytoplankton absorb C02 from oceans by photosynthesis which can be transformed into carbohydrates and stored in tissues. Respiration by plants and animals as well as decomposition returns C02 to atmosphere