Geological Carbon Cycle Flashcards
What is an overview of the carbon cycle?
CO2 in the atmosphere is taken in the rain to soil, where it is transported to the oceans and re-joins the atmosphere as gas.
What is mineral weathering?
When rocks are broken down by physical processes. e.g. Change in temperature.
What is chemical weathering?
When rocks are broken down by chemical reactions. Can produce salicylic acid, calcium and bicarbonate.
What is the Biological weathering pump?
1) Exudation: mycorrhizal associations secrete H+ into the soil, reducing pH.
2) Respiration: root and microbial respiration increase CO2 in the soil.
3) Litter decomposition: enhances microbial decomposition and more organic acids in soil (H+).
4) Evapotranspiration: increases flow of water and nutrients to plants, affects soil water residence times.
5) Stabilisation of roots: roots stabilise soil and rocks while water washes over. Favourable conditions for microbial activity and chemical weathering.
How are water-mineral-vegetation interactions affected on a microscale?
Non scale biophysical effects. e.g. Weathering on hyphal surface.
How are water-mineral-vegetation interactions affected on a regional scale?
Differences in weather. e.g. More sun, gases, volcanic disruption.
How are water-mineral vegetation interactions affected on a global scale?
Weathering and biological interactions. e.g. Increasing photosynthetic capacity, increasing root and mycorrhizal colonisation.
How has earths atmosphere evolved?
Originally no O2.
Great oxidation event: iron oxidised, red seas. Methane destroyed which led to cooling event. Ozone layer formed.
When were the first land plants and what were they like?
Late Silurian-Devonian period.
Simple stems, no leaves, spores and sporangia for reproduction.
What is the timeline for land plant evolution?
Late Silurian-Devonian period: first land plants
30MY later: leafless woody shrubs
50MY later: megaphyll leaves
How did stomatal densities differ?
Stomatal density increased from Devonian to Carboniferous period.
Why could large leaf plants not survive in high CO2 atmosphere?
They would overheat and die, require a higher stomatal density to release heat through transpiration.
When did leaf blades increase in size?
Leaf blades increased by 25 times when CO2 levels dropped in the late Paleozoic period.
Also had 8 times more stomata
