Biogeochemical Cycles and Carbon Cycle

Study Notes

Biogeochemical cycles are processes that recycle elements on Earth.
These cycles are essential for understanding how human activities impact climate and the environment.
Humans have disrupted these cycles by increasing the production of certain compounds, exceeding natural processes' abilities to regulate them.

Important terms:
- Carbon Sink: Processes or reservoirs that absorb carbon from the atmosphere, such as forests and oceans.
- Carbon Source: Processes or reservoirs that release carbon into the atmosphere, such as fossil fuel burning and deforestation.
- Fossil Fuels: Coal, petroleum, and natural gas formed from decomposed organisms over millions of years.
- Greenhouse Gas: A gas that traps heat in the atmosphere, contributing to global warming.
Important Processes:
- Photosynthesis: Plants convert carbon dioxide (CO2) from the atmosphere into organic compounds.
- Respiration: Organisms release carbon dioxide (CO2) back into the atmosphere during metabolic processes.
- Decomposition: Decomposers break down dead organisms, releasing carbon back into the atmosphere.
Sinks:
- Forests
- Oceans
- Soil
Sources:
- Fossil fuel burning
- Deforestation
- Respiration
- Volcanic eruptions
Human Impact on the Carbon Cycle:
- Fossil Fuel Burning: Releases large amounts of stored carbon into the atmosphere as CO2.
- Deforestation: Reduces the ability of forests to absorb CO2 from the atmosphere.
- Increased atmospheric CO2: Warms the planet, contributing to climate change.
- Ocean Acidification: Increased CO2 absorption by oceans reduces their capacity to act as a carbon sink, while also harming marine life.
- Melting Ice Sheets and Thawing Permafrost: Releases trapped CO2 and methane, further enhancing the greenhouse effect.

Important Terms:
- Nitrogen Fixation: Conversion of atmospheric nitrogen gas (N2) into usable forms by certain bacteria.
- Nitrification: Conversion of ammonia (NH3) to nitrates (NO3-).
- Denitrification: Conversion of nitrates ( NO3-) back to atmospheric nitrogen (N2).

Important Terms:
- No technical terms, mainly involves biological processes.

Fertilizers: Excessive use of nitrogen and phosphorus fertilizers leads to:
- Soil Saturation: Build-up of nutrients in the soil, potentially harming plants and microorganisms due to toxicity.
- Nutrient Runoff: Excess fertilizers can leach into groundwater, contaminating it.
- Eutrophication: Runoff into lakes and other water bodies causes excessive plant growth and nutrient depletion, leading to oxygen depletion and harm to aquatic life.
Nitrogen Specific Impacts:
- Loss of Symbiotic Relationships: Excess fertilizer-derived ammonia disrupts the symbiotic relationship between nitrogen-fixing bacteria and certain plants, making them dependent on fertilizers.
- Inefficient Nutrient Absorption: Fertilizer derived nutrients are not as efficiently absorbed by plants as naturally produced ones.

Thermohaline Currents: Ocean currents driven by differences in temperature and salinity, playing a crucial role in global climate regulation.
Albedo: The reflectivity of a surface, impacting the Earth's temperature balance.
- Darker surfaces absorb more light, while lighter surfaces reflect more light.
Aerosols: Solid or liquid particles suspended in the air, influencing albedo by reflecting sunlight.