Carbon Cycle: C (carbon – 6th element – “life” element) gets recycled in different
molecules – C has 4 electrons at outer edge that can make different molecules
Different Spheres:
1. Atmosphere – air – C comes in and out of the atmosphere–photosynthesis,
breathing, burning (fossil fuels – chemical energy stored– organic carbon);
ocean releasing CO2, , living things decay releases C; CO2 dissolves in rain -->
carbonic acid (acid rain) ( CO2(dissolved) + H2O ⇌ H2CO3
2. Biosphere – life – C comes in and out all living things – sugar, protein – eating,
decaying (dead bodies decay); breathing + photosynthesis
3. Hydrosphere – water – ocean soaks and releases CO2; carbonic acid dissolves
minerals --> flows into rivers and oceans
4. Geosphere – Earth – carbonate rocks (ex. CaCO3 - limestone) releasing CO2,
volcanic eruptions releases CO2 into the atmosphere; forming fossil fuels (ex.
crude oil from dead planktons, coal – dead plants – process takes millions of
years); carbonate minerals in marine life into shells; CO2 released when ocean
floor pushed down into the mantle and becomes magma
Examples of C-movements
respiration: by all living things’ (breathing – to get energy out of nutrients) – take
O2 and release CO2 C6H12O6 + 6O2 → 6CO2 + 6H2O
photosynthesis: by all green plants; plants take CO2 and make food(= sugar
C6H12O6) and release O2 6CO2 + 6H2O → C6H12O6 + 6O2
eating: animals eating plants (sugar) and animals eating animals (protein including
C) –
source: release CO2, fossil fuels, all living things that breathe, limestone…
sink: take in CO2- ex. all green plants that do photosynthesis, oceans
Amount of CO2 naturally balanced between sources and sinks – but humans’ burning fossil
fuels brings enhanced greenhouse gases and unsettle the natural balance.
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