The amount of microplastics found in our oceans is of growing concern. Gauging the size of the problem and determining successful ways to tackle it will be an essential part of future environmental policies. A sports endurance event is proving an unexpected ecological dimension to this race too.

About GB Row

The GB Row Challenge is a truly unique contest. Teams of rowers compete to be the fastest to circumnavigate the coastal waters of mainland Britain – covering a total distance of over 2000 miles. The teams set out from Tower Bridge on the 12^th June, looking to beat the current record for completing the course (which stands at 26 days and 9 hours).

Trials of the Harwin-sponsored boat entered in this year’s GB Row Challenge

Staying at sea throughout the race, the team members row continuously (taking it in turns to sleep). In addition to the physical exertions, the teams are also conducting scientific measurements during the race – sampling the microplastic concentrations in the waters they are passing through.

As well as being one of the sponsors of the event, Harwin has a major involvement in the scientific element too. Working in collaboration with the University of Portsmouth, we developed the pumps for the microplastic sampling systems fitted to the competing boats.

The threat posed by microplastics

The presence of waterborne plastics can cause all sorts of problems for the marine environment and the wildlife situated there. Much of this plastic will take a period of between 450 and 600 years to degrade.

Exposure to microplastics is one of the greatest worries. They end in our oceans through the breakup of larger plastics. UN studies estimate that there are now 500 trillion microplastic particles in the marine environment.

“Microplastics often look like food to fish and crustaceans, being eaten in large quantities. There they can irrevocably damage the health of these creatures, due to the carcinogenic properties that such materials have,” states University of Portsmouth’s Dr. Couceiro.

Until now, there has not been a comprehensive map of microplastic concentrations in British coastal waters. By making sampling for microplastics part of the activities done by the GB Row teams during the race, annually updated data on concentration changes can be obtained over time. This will also enable scientists to identify the locations around the coast where the problem is most severe.

The microplastics sampling system

By using specially designed equipment, the GB row teams take water samples. After they return, scientific staff at the University of Portsmouth will analyse the samples, recording the quantities of microplastics present.

Microplastics are typically less than 5mm in diameter.  Taking this into consideration, it was decided that 0.044mm filters would be used in the systems, meaning that as many microplastic particles could be captured as possible – without the risk of them getting blocked.

With the boats attempting a world record time, their performance couldn’t be compromised, so the systems had to be compact and lightweight. Considerable engineering effort was needed to minimise the size of each system, with them needing to be installed and operated through a 180mm-wide hatch.

The power consumption was another constraint. All instrumentation would only have 100Ah of stored energy available, which needed to last the entire race, so the sampling system had to be to ensure its pump would only consume 3 Amperes per day, but large amounts of water needed to be extracted and filtered during that time.

Low noise operation was also essential. Due to the cramped conditions, with very little room available, the rowers would be sleeping close to the pump. Therefore, it had to be designed so they would be undisturbed.

Without an off-the-shelf pump solution, it was necessary for our engineers to build bespoke equipment. Many of the parts were CAD created and 3D printed.

Component materials were carefully selected, ensuring they would not contaminate the extracted samples – as this would affect the integrity of the data compiled. Stainless 316 was used for the filters to prevent plastic contamination, and to safeguard the system from saltwater corrosion.

Microplastics sampling systems (using Harwin-developed pumps) have been used on 3 GB Row teams’ boats. Typically, the boats were sampling at a rate of 0.7Lpm, which equates to 126L of water being sampled every day. This requires 400mA of current from the battery.

Alex Mair designed the pump for GB Row

As Alex Mair, Technical Support Engineer at Harwin, explains; “Designing the pump for the sampling system has been a different kind of challenge for us, but precision engineering for harsh environments is our specialty.”

The 2022 GB Row Challenge took an unexpected turn, when the heavy storms in late June resulted in the competing teams needing to be rescued from the Irish Sea. Despite severe damage to several of the boats, the robust Harwin pump design ensured that sampling continued once the race resumed. The use of microplastics sampling systems incorporating these pumps will be regular a feature on GB Row Challenge boats participating in years to come.