Chapter 12 - Global Biogeochemical Cycles Flashcards
What is biogeochemistry?
It is the science that looks at the biotic controls on chemistry of the environment and the geochemical control of ecosystem structure and functions
What is the phosphorous cycle?
It is the rate of P flow through the global environment, which is 3x greater now than it was before industrial and agricultural revolutions. This intensification/acceleration is important because it causes eutrophication. Most P is inaccessible and recycling is very important!
What is P used in?
Used in fertilizers, cleaning agent compounds and there is more dust with P because of desertification. Humans influence is mining (sudden abundance)
What is the sulphur cycle?
It is a complex and essential cycle, but does not limit PP. There were many sulphur gases released into the atmosphere from fossil fuel burning (like coal) and was a major contributer to acid rain, but is now more so N.
How do scientists know the climate has significantly warmed in the past 200yrs?
They can figure this out based on atmospheric gases trapped in Antarctic ice sheets to identify the ppm and the approximate year. Volcanic ash can also help to verify a year.
What is a carbon source?
Something that releases carbon into the atmosphere. Fossil fuel burning is the main source of CO2 release as it is responsible for more than 90% of the total flux. Deforestation, wood burning, respiration and decomposition of dead biomass/OM is also a source of CO2
What is a carbon sink?
It is a site of storage of carbon. The ocean and terrestrial CO2 sinks are relatively equal in storage capabilities and are critical in reducing fossil fuel combustion. There’s lots of uncertainty with how much terrestrial sinks can hold, but ocean sinks are known with high precision
What is responsible for the CO2 flux in the deep ocean?
The great oceanic conveyor belt is constantly moving CO2 . The conveyor belt is slowing as waters warm, which results in less CO2 uptake and further warm the earth globally (positive feedback loop)
Why is over-relying on the ocean to take up CO2 potentially consequential?
The more CO2 that is uptaken by the oceans, the more acidic oceans become (due to creation of carbonic acid). It is already 30% more acidic since the industrial revolution. This is problematic for species with carbonate shells/structures, like corals
Describe methane in relation to CO2
It is more potent than CO2, but its concentration and residence time is much lower
What is radiative forcing?
It is the imbalance between incoming solar radiation and outgoing infrared radiation. It expresses a change in energy in the atmosphere due to GHGs.
ex. CO2 increases warming while some aerosols reflect back light and can reduce warming
How do methane sinks work?
They alter methane to other compounds so it less destructive.
ex. biggest method is atmospheric photooxidation, which oxidizes methane into CO2 and H2O
What is residence time?
It is the amount of time a molecule/gas stays in the same place, usually referring to the atmosphere
ex. CH4’s atmospheric residence time is 12 yrs opposed to 100yrs for CO2
What is methanogenesis?
It is the production of methane by bacteria in the absence of O2. Decomposers use O2 to break down dead OM and produce CO2, but in anaerobic conditions, CH4 produced instead
What is a positive feedback loop aka?
Amplifying
