When a hurricane makes landfall, it causes several damage and leaves a trail of physical destruction. What we cannot see, however, is the load of harmful microplastics that these storms carry across the world.
A group of researchers from Dalhousie University tried to discover how microplastics can be carried and spread through the atmosphere during significant storms. They focused on the samples of atmospheric fallout during Hurricane Larry when it passed over Newfoundland, Canada.
Onslaught of Hurricane Larry
On September 11, 2021, Larry landed near Great Bona Cove as a Category 1 hurricane. It hit the area with winds of 130 kilometers per hour and gusts of more than 180 kilometers per hour.
The storm followed a track offshore of the eastern seaboard of the U.S. and Eastern Canada, making its trajectory over the ocean before landfall. This made the weather event a unique opportunity for the scientists to conduct their research.
Hurricane Larry did not travel close to major areas, generally considered major sources of airborne microplastics. However, it passed over areas of the ocean, such as the North Atlantic garbage patch, where the current traps high concentrations of plastics in the surface waters.
Understanding Atmospheric Microplastic
Led by Dalhousie University environmental science master's student Anna Ryan, the researchers combined laboratory analysis with numerical modeling simulations to better understand the phenomenon. As Hurricane Larry lashed the Canadian province, the team headed to a rural area on its track to collect air samples.
A large glass cylinder was set out near St. Michaels, a community of less than 300 on the Avalon Peninsula. It was in place for six hours to collect samples from before, during, and after the storm.
Microplastics were found in every air sample collected in the area when Hurricane Larry made landfall and in the days that followed. The highest concentration of plastics was found during the peak of the storm, with more than 100,000 particles per square meter per day.
The study "Transport and deposition of ocean-sourced microplastic particles by a North Atlantic hurricane" offers new insight into the origin and amount of microplastics deposited in the environment. It reveals that hurricanes can transport these fragments faster than ocean currents to areas that do not receive regular deposits from other sources.
According to Ryan, the atmosphere enables the particles to travel greater distances in less time than in the ocean. It also deposits particles in remote areas inaccessible by other transport mechanisms. Meanwhile, the ocean can be considered the "ultimate sink" but may not be where the microplastics stay.
The microplastics found in the samples were later analyzed to help track their origins. Using back-trajectory modeling, the Dalhousie scientists concluded that the samples were sourced from the Atlantic garbage patch as the hurricane's passer. Ocean currents are believed to transport marine microplastic worldwide, concentrating in ocean gyres where the current patterns become circular to create massive oceanic garbage patches.
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