Microbes can clean oil spills faster when sand has more oxygen, study finds
New research from Singapore shows that natural micro-organisms can break down oil spills far more effectively when beach sand is well-drained and rich in oxygen. The findings, published in August in the peer-reviewed journal Environmental Science and Ecotechnology, could help authorities respond to oil spills with simpler, low-cost measures.
Professor Stephen Brian Pointing of the National University of Singapore led the study. His team found that microbes degraded 40 per cent of oil in oxygen-rich sand over 90 days, compared with only 5 per cent in waterlogged, oxygen-poor sand.
Oxygen is a key factor in how efficiently microbes break down oil, said Pointing. While bacteria can still degrade oil without oxygen, the process is much slower and less effective.
What the research revealed about oil-eating microbes
The study identified 298 species of microbes that break down oil in sand collected from Bendera Bay on St John's Island, a beach set aside for long-term scientific research. Using metagenomic sequencing, the team characterised the genetic material in the samples and mapped how the microbes degrade oil.
In oxygen-rich sand, bacteria from the group Alphaproteobacteria use oxygen to rapidly break down oil. In waterlogged conditions, other bacteria take over but work less efficiently.
The researchers also found that some microbes are unusually adapted to both oxygen-rich and oxygen-poor conditions. These microbes may act as metabolic bridges, allowing oil degradation to continue even as beach conditions change, such as during tides.
How this helps oil spill clean-up efforts
The research builds on earlier work from September 2025, prompted by one of Singapore's worst oil spills. In June 2024, a dredging boat collided with a bunker vessel, releasing more than 400 tonnes of oil into the nation's southern waters.
Pointing said: “The first study was basically showing that the microbes were involved in cleaning up the sand from that big spill in 2024, and this study is explaining exactly how they achieve it.”
He added: “In the past, people knew that the oil disappears, but they didn't know what's causing it. We have shown that 40 per cent of the oil is being broken down by the microbes, which is quite a significant amount. This means that keeping our beaches healthy in terms of their microbial populations is a really important part of management.”
Practical advice for responders
The team is now building predictive models to identify which beaches are likely to break down oil naturally and quickly, and which ones will need active intervention. This could mean leaving some beaches alone, or taking steps to aerate the sand, improve water drainage, or adjust beach slopes.
“The end goal is to provide some practical and tractable low-cost advice that will just let us plan better instead of having to deploy massive effort to remove oil,” Pointing said.
He noted that Singapore's equatorial climate, busy shipping lanes, and dynamic tropical coastlines make it an ideal place for this research. Most detailed knowledge of major marine oil spills has historically come from other regions.
“Recovery from an oil spill does not stop when the visible oil disappears,” he said. “There is a largely invisible biological recovery process continuing within the sediment. Understanding that gives us another tool for protecting and managing tropical coastlines.”