GHG FOCUS ON METHANE Flashcards
What are negative emission technologies? what are some examples?
- they involve the absorption of CO2 at low concentration from the atmosphere
- afforestation & reforestation
- bioenergy carbon capture & storage
- biochar
- enhanced weathering
- direct air capture
- ocean fertilisation
- soil carbon sequestration
What are some sources of atmospheric methane?
- landfills
- flooded rice fields
- natural wetlands
- biomass burning
- fossil fuels
- gas hydrates
- termites
- ruminants
what do microbes produce when they break down biomass?
methane
how much methane is produced per year?
542-852 Tg per year
what are the microbes called that perform methanogenesis?
methanogens
what is methanogenesis? where does it occur?
the production of methane by bacteria
produced by decomposition in the absence of oxygen (methanogens are strict anaerobes)
occurs in flooded soils and other environments with a low redox potential (rumen, wastewater plants, lake sediments)
what are ocean hydrates made from?
frozen hydrates
what are methane hydrates? where are they mainly found? what conditions are they stable under?
solid where methane is trapped in frozen (crystal) water.
mainly found along continental shelves
also in permafrost
stable at low temperature and high pressure
what is catastrophic methane hydrate release?
when sea level falls, methane is released into the atmosphere;
pressure release causes hydrate to dissociate, there’s a sediment slump and the gas hydrates destabilise
what are the key enzymes of aerobic methanotrophs?
methane monooxygenase
how does methylomirabilis oxyfera make oxygen?
they tae 2NO2- and split it into N2 and O2
what is the potential negative of hydroelectric dams?
large amounts of greenhouse gases (methane) is produced by degassing as flooded plants/soil causes decay after reservoir is first filled, as well as phytoplankton and leafy plants, releasing gases
what is the potential negative of hydroelectric dams?
large amounts of greenhouse gases (methane) is produced by degassing as flooded plants/soil causes decay after reservoir is first filled, as well as phytoplankton and leafy plants, releasing gases
global warming is not only about CO2, but also … and …
CH4 & N2O
which NETs are considered stable in permanence?
- bioenergy carbon capture and storage
- biochar
- enhanced weathering
- direct air capture
