Chemical tank accident: Public urged to avoid water activities near Tuas Second Link, Raffles Marina

Key Concepts:

• Propylene Glycol: A chemical commonly found in food and cosmetics, generally considered non-hazardous but can cause skin irritation and respiratory issues in sensitive individuals.
• Biochemical Oxygen Demand (BOD): The amount of oxygen consumed by microorganisms when decomposing organic matter in water. High BOD can lead to oxygen depletion.
• Dissolved Oxygen Levels: The amount of oxygen present in water, crucial for aquatic life.
• Contingency Plans: Pre-arranged strategies to address potential emergencies or disruptions.
• Aquaponics: A system that combines aquaculture (raising fish) and hydroponics (growing plants without soil) in a symbiotic environment.
• Desalination Plants: Facilities that remove salt from seawater to produce fresh water.
• Kalongs: Traditional offshore fish farms.

Chemical Tank Incident and Response

• Incident: A chemical tank containing propylene glycol fell into the sea near the TW second link (Malaysia side) following a collision between two heavy tankers on Thursday evening.
• NEA Advisory: The National Environment Agency (NEA) advised the public to avoid water activities (swimming, water sports, recreational fishing) near the second link and Raffles Marina as a precaution.
• Propylene Glycol Properties: Officials confirmed that propylene glycol is generally not hazardous and breaks down naturally in water. However, it can lower dissolved oxygen levels.
• Monitoring: NEA is closely monitoring water quality in the affected areas.
• Fish Farm Alert: Fish farms, particularly in the Limchuk Kang area, were alerted to watch for unusual conditions due to potential oxygen depletion.
• Desalination Plants: Singapore's desalination plants remain unaffected, with the National Water Agency overseeing seawater intake.

Potential Risks and Expert Opinion

• Common Uses: Propylene glycol is found in processed food, medication, and cosmetics.
• Human Health: While generally safe, it can cause skin irritation or respiratory issues in intolerant individuals.
• Marine Life: The primary risk to marine life is the high biochemical oxygen demand (BOD) of propylene glycol. As it degrades, it consumes oxygen, potentially leading to oxygen depletion and harming aquatic organisms.
  • Quote: "There is a high biochemical oxygen content. So what this means is that when it degrades in water, it consumes oxygen and this will lead to oxygen depletion in the water body and this may cause harm to the aquatic uh organisms."
• Raffles Marina: Postponed sailing races scheduled for the weekend as a precaution.

Fish Farm Perspectives and Contingency Plans

• Offshore Farms (Kalongs): Fish farmers operating offshore (kalongs) are potentially more affected due to direct exposure to seawater.
• Contingency Plans: Offshore farms typically have robust contingency plans in place.
  • Example: One farmer mentioned having water probes that monitor oxygen levels 24/7. SFA (Singapore Food Agency) will alert the farm if low oxygen levels are detected, triggering the activation of emergency aeration systems.
  • Quote: "We have water probes um in the water 24 hours. So it it can be monitored online and uh also uh SFA will uh actually if there is detected levels of very low oxygen. So what we do is we will actually activate the emergency aerration system in the farm itself."
• Land-Based Farms: Land-based fish farms using aquaponics are not directly affected by seawater pollution. They use freshwater (rainwater) to grow plants, which filter the water for the fish.
  • Quote: "So I use the rain water because the rain water don't have any salty things. So so that then we can produce the farm can produce two two things fish and the vegetable. So aquaponic don't worry about any uh uh sea water uh pollution."
• NEA Sampling: The National Environment Agency collected water samples from the waters on Friday.

Synthesis/Conclusion:

The incident involving the propylene glycol tank falling into the sea near the second link prompted a swift response from Singaporean authorities. While propylene glycol is generally considered non-hazardous, the potential for oxygen depletion posed a risk to marine life. The NEA is actively monitoring water quality, and fish farms, particularly offshore operations, have activated contingency plans. Land-based aquaponic farms are not directly affected. The situation highlights the importance of preparedness and monitoring in mitigating the environmental impact of such incidents.