Biogeochem - Methane Flashcards
Properties of Methane’s life and efficiency
25x stronger greenhouse gas than CO2
Shorter atmospheric half-life than CO2
critical for short-term climate warminal
methane chemical formula
CH4
What is the product when methane is used as a source of energy?
Electrons are taken from methane, given to oxygen (electron acceptor) and oxidised to form CO2 and Water
what are the 2 ways that methane is produced?
- Biological methane production
- thermogenic methane production
what are the 3 pathways in which methane can be produced
CO2 pathway
Methylotrophic pathway
Aceticlastic pathway
What organisms methane oxidise
(hint oxic and anoxic…)
Aerobic methane oxidising bacteria and anaerobic methane oxidising bacteria
how does climate change impact methane oxidation?
This the temperature increasing, more dead zones are being created, increasing the number of anoxic regions
Anoxic regions are where the the methane is produced. If the anoxic areas increase the methanogens get more active which increases the CH4 production, inreasing the proportion of the anoxic zones.
The imbalance between the aerobic oxidising bacteria and the anaerobic oxidising bacteria and methane production can cause an increase in methane being released into the atmosphere
In aerobic methane oxidation, what is sMMO and when is it used?
an enzyme with an iron atom at its centre. It oxidises CH4 to produce CO2 or organic carbon for the cell.
It is used when copper is limited
what electron acceptors can anaerobic methane oxidation use?
nitrate
sulphate
manganese
iron oxides
what is pMMO
an enzyme with a copper atom at its centre. It oxidises CH4 to produce CO2 or organic carbon for the cell.
it is used when copper is abundant
what is a methane hydrate
a methane molecule surrounded by a cage of interlocking water (ice) molecules
how do methane hydrates form?
At low temperatures and high pressures, water molecules form ice which surround methane molecules in a cage and preserves them.
what is the likely outcome for methane hydrates with climate change
the methane hydrates are going to warm, ice will melt and the methane will be released into the atmosphere
how much methane can be released in 1m3 of hydrate?
164m3 of methane gas
whats the difference between biogenic methane and thermogenic methane?
biogenic methane formed as an end member from the remineralisation of organic matter in sediments
thermogenic methane formation during catagenesis of kerogen
