Carbon more than 8,000 years old has been found inside the world’s deepest blue hole — the Yongle Blue Hole (YBH).

Yongle Blue Hole (YBH)

• The deepest known marine cavern is the Yongle blue hole, which measures roughly 300 metres from top to bottom.
• Blue holes are marine caverns filled with water and are formed following dissolution of carbonate rocks, usually under the influence of global sea level rise or fall.
• Its waters are mostly isolated from the surrounding ocean and receive little fresh water from rainfall, making it a rare spot to study the chemistry of oxygen-deprived marine ecosystems.
• What distinguishes them from other aquatic caverns is that they are isolated from the ocean and don’t receive fresh rainwater.
• They are generally circular, steep-walled and open to surface.

Significance of YBH

• YBH has a depth of 300 metres, far deeper than the previously recorded deepest blue hole, Dean’s Blue Hole in Bahamas, which had a depth of 202 metres.
• However, like most blue holes, it is anoxic i.e. depleted of dissolved oxygen below a certain depth. This anaerobic environment is unfavorable for most sea life.
• Such anoxic ecosystems are considered a critical environmental and ecological issue as they have led to several mass extinctions.
• Concentrations of carbon, usually found in deep marine holes like YBH, provide a natural laboratory to study carbon cycling and potential mechanisms controlling it in the marine ecosystem.
• The transition from aerobic to anaerobic environment adversely affects the biogeo-chemistry of the ocean.

Get an IAS/IPS ranker as your 1: 1 personal mentor for UPSC 2024

Attend Now