Three years after the bulk carrier MV Wakashio tragically ran aground on a coral reef off the coast of Mauritius, releasing an alarming 1,000 tonnes of a new type of marine fuel oil, research from Curtin University has revealed that this toxic substance continues to contaminate a sensitive mangrove forest. This area is adjacent to significant Ramsar conservation sites, highlighting the urgent need for action.
The 2020 MV Wakashio oil spill has attracted significant international media attention, highlighting the serious health, social, environmental, and economic effects on Mauritius. Yet, there is very limited scientific research/data accessible on the chemical composition and fate of the spilled oil beyond the analyses of the source oil and one field sample collected three weeks after the grounding.
When the MV Wakashio ran aground on a reef off the southeast coast of Mauritius in July 2020, the approximately 1000 tons of oil that were released might be viewed as relatively typical when compared to prior spills of heavy fuel oils (HFO).
Dr. Alan Scarlett, the lead researcher from Curtin’s WA Organic and Isotope Geochemistry Centre in the School of Earth and Planetary Sciences, has confirmed that the chemical’ fingerprint’ of the oil discovered in mangrove sediments closely aligns with the Very Low Sulphur Fuel Oil (VLSFO) discharged by the Wakashio in 2020. This incident marks the first recorded spill involving this hazardous type of fuel, reinforcing the importance of safeguarding our marine ecosystems.
“Local communities in Mauritius have been aware of oil contamination in the mangrove wetlands since the Wakashio spill, but no official confirmation had been made regarding the source,” Dr Scarlett said.
“Identifying and acknowledging this contamination is crucial, both for the people of Mauritius and for global understanding, as little is known about how this new marine fuel behaves once spilled.”
Dr. Scarlett stated that samples from the mangrove wetlands, along with a reference site believed to be uninfluenced by the spill, underwent analysis through advanced chemical methods.
“We confirmed the reference site was free of oil contamination, while another site contained oil originating from the Wakashio’s fuel tanks,” Dr Scarlett said.
“We found the spilled oil had undergone substantial weathering and biodegradation in the three years since the accident, and this had removed or reduced the levels of many of its toxic compounds. However, the ongoing presence of the oil could still pose an unknown risk to the sensitive mangrove ecosystem.”
In collaboration with the esteemed Woods Hole Oceanographic Institution, the Curtin research team successfully obtained a distinctive chemical ‘fingerprint’ of the spilled oil, allowing them to definitively confirm its presence in the mangrove sediments.
Furthermore, the study conducted a thorough comparison of the behavior of Wakashio’s VLSFO alongside traditional marine heavy fuel oils, utilizing advanced models developed with the National Oceanic and Atmospheric Administration’s premier oil spill scenario tool, WebGNOME-ADIOS.
“Our modeling suggested more of the Wakashio’s fuel would evaporate, naturally disperse, or sink compared to traditional fuels, but assessing the impact on organisms remains challenging,” Dr. Scarlett said.
Journal reference:
- Alan G. Scarlett, Robert K. Nelson, Marthe Monique Gagnon, Christopher M. Reddy, Kliti Grice. Very low sulfur fuel oil spilled from the MV Wakashio in 2020 remains in sediments in a Mauritius mangrove ecosystem nearly three years after the grounding. Marine Pollution Bulletin, 2024; DOI: 10.1016/j.marpolbul.2024.117283
