SOURCES AND SINKS

CO2

• 
• Carbon Dioxide is a VARIABLE gas
• Sources: Animal respiration, burning of fossil fuels, deforestation, outgassing from ocean
• Sinks: Ocean, plants (photosynthesis)

METHANE

• Methane is a VARIABLE gas
• Sources: Agriculture (farms, manure), wetlands, outgassing from earths crust, decomposition.
• Sinks: The troposphere- contains a hydroxyl radical which converts methane into CO2 and water vapour

METHANE

TROPOSPHERIC OZONE

• Ozone is a VARIBALE gas
• Sources: Sunlight + pollutants reacting chemically (pollutants from cars, factories, power plants, etc.) , influx from stratosphere
• Sinks: photochemical ozone destruction due to sunlight resulting in hydroxyl radicals
• 

NITROGEN

• Nitrogen is a PERMANENT gas
• Sources: denitrifying microorganisms
• Sinks: used by animals in construction of proteins , used in plants

OXYGEN

• Oxygen is a PERMANENT gas
• Sources: byproduct of photosynthesis,
• Sinks: used in respiration, combustion, corrosion

ARGON

• Argon is a PERMANENT gas
• Sources:Decay of Potassium-40
• Sinks: Atmospheric argon has no sinks and gradually accumulates

HELIUM

• Helium is a PERMANENT gas
• Sources: underground gas wells where radioactive helium has collected from igneous rock
• Sinks: it floats out into space