2.3 Biogeochemical Cycles

Flashcards covering key concepts from the Biogeochemical Cycles lecture, focusing on carbon, nitrogen, and phosphorus cycles, ecosystem dynamics, and human impacts.

What are biogeochemical cycles?

The movement and transformation of elements like carbon, nitrogen, and phosphorus between the atmosphere, hydrosphere, lithosphere, and biosphere.

What are the components of the biogeochemical cycle?

Biosphere, Water, Oxygen cycle, Carbon cycle, Phosphorus cycle, and Nitrogen cycle.

How do elements recycle in the Earth’s System?

Closed systems that recycle elements between abiotic and biotic stores, with flows moving elements as transfers or transformations.

What are sinks in biogeochemical cycles?

Areas of net accumulation where elements are absorbed faster than they are released.

What are sources in biogeochemical cycles?

Areas of net release where elements are discharged faster than absorbed.

What do organic stores refer to?

Carbon contained in living or recently living organisms and materials derived from them.

What do inorganic stores include?

Includes CO2 in the atmosphere, dissolved CO2 in the ocean, Carbonate and Hydrogen Carbonate Ions in the Oceans, Sedimentary Rocks of carbonate, mineral parts of soil, volcanic reservoirs, dissolved gases in groundwater.

What happens to carbon during Photosynthesis?

Plants and photosynthetic organisms absorb CO₂ from the atmosphere, converting it into glucose and other organic compounds using sunlight energy.

How does combustion affect the carbon cycle?

Burning fossil fuels releases CO₂ into the atmosphere.

How does fossilization store carbon?

Organic matter under prolonged pressure transforms into coal, oil, and natural gas deposits.

What is the role of Death and Decomposition in the carbon cycle?

Decomposers break down dead organisms, releasing CO₂ and nutrients back into the soil and atmosphere.

What are transfers in the carbon cycle?

The movement of carbon from one store to another without changing its form.

What are transformations in the carbon cycle?

Changes in the chemical form of carbon as it moves between stores.

What is carbon sequestration?

Capturing gaseous and atmospheric carbon dioxide and storing it in a solid or liquid form.

How does Natural or Biological Sequestration works?

Photosynthesis converts carbon to biomass, decomposition captures carbon in soil, and ecosystem restoration.

What is the process of Carbon Capture by humans?

Taking gaseous and atmospheric CO2 and storing it in a solid or liquid form, usually in geological formations.

Why do young forests act as carbon sinks?

High photosynthetic activity leads to significant CO₂ uptake.

Why do Mature forests act as carbon stores?

Balanced rates of photosynthesis and respiration result in stable carbon storage.

Why Forests Affected by Fire or Deforestation act as Carbon Sources?

Rapid release of CO₂ from decomposing biomass and reduced photosynthesis.

How were Fossil fuels formed?

Ecosystems acted as carbon sinks in past eras and become carbon sources when burned.

What agricultural techniques increase carbon sinks?

Crop rotation, cover crops, and no-till farming.

What agricultural techniques increase carbon sources?

Drainage of wetland, monocultures, and heavy tillage.

What is crop rotation?

Rotating crops with different root structures and nutrient needs to break up compacted soil.

What is No-till farming?

Planting crops directly into the soil without disturbing it with tillage implements, minimizing soil disturbance.

How does heavy tillage is destructive?

Breaks up the soil structure, releasing stored carbon.

What happen during physical dissolution

Carbon dioxide molecules in the atmosphere dissolve in seawater, forming carbonic acid.

What happen during Biological uptake?

Marine organisms use carbon dioxide for photosynthesis, incorporating it into their biomass.

What is ocean acidification?

Excess CO2 in the atmosphere is absorbed by the oceans, decreasing the pH of seawater.

How Impacts of Ocean Acidification affect Marine Life?

Weakens marine organisms, affecting their growth, reproduction, and survival.

What are Low carbon technologies?

Renewable energy sources that produce electricity without emitting greenhouse gases.

How we can achieve Reduction in fossil fuel burning, soil disruption and deforestation?

Shifting to renewable energy sources, reducing soil disruption, and reducing deforestation.

How Carbon Capture and Storage help?

Reforestation provides a natural carbon sink, while artificial sequestration can capture carbon dioxide that is already in the atmosphere.

What are carbon stores that Lithosphere contains?

Fossil fuels and rocks, such as limestone, that contain calcium carbonate.

What the Lithosphere cycle ensures?

Ensure that the elements that make up rocks are always being recycled and utilized.

Example of hard parts that contain calcium carbonate

Reef-building corals and shellfish produce calcium carbonate skeletons that can be preserved over time and eventually form limestone.

How coal is formed?

Organic matter from partially decomposed plants became fossilized in coal.

How Oil and Natural gas were formed?

Organic matter from partially decomposed marine organisms became fossilized in oil and natural gas held in porous rocks.

What methane is produced from?

Dead organic matter in anaerobic (oxygen-lacking) conditions.

What is Methanogenesis?

Process where microorganisms called methanogens convert organic matter into methane gas (CH4) only occurs in anaerobic environments, which means those that lack oxygen.

Where Methanogenic bacteria can be found?

Swamps, rice paddies, and the stomachs of cattle and other ruminants.

Methane cycle

Methane has a residence time of about 10 years in the atmosphere and is eventually oxidized to carbon dioxide

What are the Organic Stores that the nitrogen cycle contains?

Proteins and other nitrogenous carbon compounds (amino acids, DNA, RNA etc)

What are the Inorganic Stores that the nitrogen cycle contains?

Nitrogen gas (N2), Ammonia (NH3), Ammonium (NH4 +), Nitrates (NO3 -) and Nitrites (NO2 -)

What happen during Nitrogen Fixation?

N2 is fixed by some prokaryotes and cyanobacteria (blue green algae) (and lightning) using the nitrogenase enzyme to form NH3

What Roles do Bacteria have in the nitrogen cycle?

Ammonification, Nitrogen Fixation, Nitrification, and Denitrification

What happen during Ammonification?

Decomposition by fungi and bacteria of dead organic matter and animal excreta to NH4 and then NH3 which then can be nitrified

Where does Denitrification occurs?

Denitrification only happens in anaerobic conditions, such as soils that are waterlogged

Example of trees that reduce nitrogen fixation when trees are nitrogen fixing

Alder (Alnus) or Acacia

How Deforestation change the nitrogen cycle?

Reduces the number of trees reducing nitrogen fixation when trees are nitrogen fixing

Planetary boundary for the nitrogen cycle

Nitrates in the biosphere from human activities have led to the planetary boundary for the nitrogen cycle being crossed

How the biosphere from human activities affect ?

Aquaculture, Agriculture, deforestation, and urbanization

How Monoculture affects?

Reduces the soil's ability to retain nutrients and organic matter, leading to carbon release

What is the Haber process?

The Haber-Bosch process is an industrial process that produces ammonia from nitrogen and hydrogen for use as fertilizer

Measures to bring the planetary boundary back to the safe operating space

Efficient Fertiliser Use, Promoting Sustainable Agriculture including cover cropping and crop rotation, Reducing Nitrogen Emissions