Anoxic Marine Basins for Carbon Sequestration UPSC

ANOXIC MARINE BASINS

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Picture Courtesy: https://phys.org/news/2016-02-animals-oxygen.html

Context: Researchers have identified anoxic marine basins as potential sites for large-scale carbon sequestration by depositing plant biomass in oxygen-deprived zones on the seafloor, offering an effective strategy with minimal impact on marine life.

Details

Atmospheric CO2 levels are rising at an alarming rate, primarily due to human activities like fossil fuel burning. This increase is causing significant climate change, with potentially devastating consequences.
To mitigate climate change, we need to remove CO2 from the atmosphere and store it securely. This process is known as carbon sequestration.
Anoxic Marine Basins are barren, oxygen-free zones on the seafloor, isolated from the main oxygen-rich currents. Their unique characteristics make them potential candidates for large-scale carbon sequestration.

Why Anoxic Basins?

Minimal Ecological Impact: Lack of oxygen limits the presence of oxygen-dependent life, minimizing potential harm to marine ecosystems.
Ideal Preservation Conditions: The anoxic environment favors the preservation of organic matter, potentially locking away carbon for centuries or even millennia.
Large Storage Capacity: Some basins, like the Black Sea, have immense depths and areas, offering the potential to store significant amounts of CO2.

About Anoxic Basins

Feature	Details	Example
Definition	Bodies of water devoid of dissolved oxygen (O2)	Black Sea, Cariaco Trench, Baltic Sea
Formation	Stratification: Density differences (salt or temperature) create layers, impeding vertical mixing and oxygen replenishment. Organic matter decomposition: Microbes consume oxygen while breaking down organic matter, depleting levels. Limited circulation: Restricted flow from surrounding oxygenated waters.	Deep, enclosed basins with limited connections to open ocean
Types	Permanent: Anoxia persists year-round. Temporary: Anoxia occurs seasonally or during specific events.	Black Sea (permanent), Baltic Sea (seasonal)
Characteristics	Low oxygen: < 0.2 mg/L or undetectable O2. High hydrogen sulfide (H2S): Produced by microbes under anoxic conditions, creating a rotten egg smell. Extreme conditions: Salinity, temperature, pH can vary depending on basin. Unique microbial communities: Adapted to anoxic environments, utilizing alternative electron acceptors (e.g., nitrate, sulfate) for respiration.	Black Sea: Hypersaline, anoxic throughout. Cariaco Trench: Anoxic bottom layer, high H2S.
Ecological impact	Limited animal life: Most animals cannot survive without oxygen. Chemosynthetic communities: Microbes thrive, forming the base of the food chain. Nutrient cycling: Play a role in global cycles of carbon, nitrogen, and other elements.	Black Sea: Dominated by microbial communities. Cariaco Trench: Supports unique chemosynthetic organisms.
Potential implications	Climate change: May be affected by warming temperatures and increased stratification. Carbon sequestration: Could be used for storing captured CO2, but concerns exist about potential environmental consequences. Resource exploration: Anoxic sediments may contain valuable minerals, but extraction raises environmental concerns.	Studies ongoing to assess impact of climate change and potential uses.

Conclusion

Anoxic marine basins offer a potentially valuable option for deep-sea carbon sequestration. However, thorough research and responsible implementation are essential to ensure its effectiveness and minimize environmental risks. As we race against time to address climate change, exploring and refining innovative solutions like this is crucial for achieving our carbon reduction goals.

PRACTICE QUESTION

Q. Which of the following is NOT a characteristic of anoxic marine sediments?

A) High concentration of hydrogen sulfide

B) Presence of chemosynthetic bacteria

C) Abundance of macroscopic animals

D) Decomposition of organic matter

Answer: C

Explanation:

Anoxic environments lack sufficient oxygen for most animals to survive. While chemosynthetic bacteria thrive in these conditions, macroscopic animals are typically absent.