The gruelling 1.5 km swim took place in Strathclyde Loch, a man-made loch approximately one square kilometre in size that is owned and operated by North Lanarkshire Council. The loch is a popular venue for professional and amateur water sports.
Over the years, however, water sports have sometimes been suspended because of contamination by bacteria and blooms of blue-green algae, which can cause severe reactions in humans and animals.
To keep the athletes safe, scientists used impermeable barriers in the water to separate the swim area from the rest of the loch. This allowed it to be managed like a huge open water swimming pool within the loch, blocking off pollution and allowing steps to clean and improve the water.
A chemical treatment, Phoslock, was used to reduce the concentration of phosphorus in the water and thereby reduce the growth of blue-green algae.
In the run up to the games the water was also dosed with hydrogen peroxide, a powerful oxidising agent that can be used to remediate low oxygen levels in polluted water. It is also toxic to blue-green algae, meaning it can be used to manage algal blooms.
After dosing with hydrogen peroxide levels of blue-green algae in the swim area fell by 80-85 per cent within 24 hours and by 97 per cent within four days. And even when a bloom of blue green algae occurred in the loch outside the swim area, levels within the swim area remained low.
APEM had previously trialled the use of hydrogen peroxide and closely monitored the results.
The trial assessed and confirmed site-specific characteristics, requirements and behaviour, tested logistics and helped to refine the correct dose and dose rate. A series of laboratory trials were undertaken to investigate the break-down of peroxide in the loch.
APEM began helping to prepare the loch for the games in 2012, when we were commissioned by the Scottish and Northern Ireland Forum for Environmental Research and North Lanarkshire Council to help to deliver the Strathclyde Loch Restoration Project.
We also worked very closely with the Scottish Environment Protection Agency, the Scottish government and Scottish Water. APEM had previously worked on the 2002 Manchester Commonwealth Games and a number of major triathlon and open water swimming events.
Adrian Williams, director of freshwater and marine ecology at APEM, said: “It was fantastic to be involved in such a high profile and innovative project. We’re deeply indebted to our clients and partners, who made these innovative approaches possible and ultimately led to a perfect day of sport.”
But the final verdict came from gold medallist Alastair Brownlee, who told reporters: “I thought it was a wonderful course… I was thinking while I was swimming: ‘this is really nice water.’”
If you have any queries, please contact Heather Webb, principal aquatic scientist.
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