It is well known that microplastics have infiltrated much of the world’s oceans, where these persistent pieces of waste threaten the livelihoods of marine life. However, truly quantifying the global scale of the problem remains a challenge.
A pair of researchers is now proposing a new approach to tracking small pieces of plastic in the world’s oceans. They think this should be done remotely, from space. In a study published this month in IEEE Transactions on Geoscience and Remote Sensing, they describe their new satellite-based approach, which refers to the seasonal flow of microplastics in the oceans.
The problem of persistent plastics in the environment is woman. Annual global production of plastics has been growing steadily every year since the 1950s, reaching 359 million tons in 2018. “Microplastic contamination poses a threat to humans and our environment, the extent of which cannot be well determined by conventional sampling alone. To work on better solutions, we need to know more about the problem itself,” explains Madeline Evans of the University of Michigan.
Over the past few years, Professor Evans and Christopher Ruf have collaborated on an approach developed and validated using NASA’s Cyclonal Global Navigation Satellite System (CYGNSS), which uses bistatic radar to track microplastics in the ocean
The concept is based on how the presence of microplastics changes the surface of the ocean. “The presence of microplastics and surfactants in the ocean causes the ocean surface to be less responsive to the ‘roughening’ effect of wind,” says Ruf.
Ruf and Evans therefore examined that According to CYGNSS measurements, how much the ocean surface is disturbed by the wind. Furthermore, they assess the extent to which they deviate from those predicted and, in addition to local wind speeds, whether they can be used to confirm the presence of microplastics. Moreover, their approach has been validated compared to other models for predicting microplastics. However, while existing models provide a static snapshot of the extent and extent of microplastic contamination, this new approach using CYNGSS can be used to real-time understand microplastics concentrations.
Their approach to analyzing global samples researchers have found that microplastics concentrations in the northern Indian Ocean are generally highest in late winter or early spring and lowest in early summer. These flows coincide with the monsoon season, prompting the authors to hypothesize that river outflow patterns into the ocean and the diluting force of rain may affect microplastic concentrations, although further research is needed to confirm this. In addition, a strong seasonal pattern was observed in the Great Pacific Garbage Spot, where the concentration of microplastics was highest in summer and lowest in winter.
“The seasonal shift in our measurements surprised me the most. Before I worked on this project , I envisioned the Great Pacific Garbage Spot as a constant, mostly static mass. I was surprised to see such a dynamic behavior of this large accumulation of microplastics, “said Evans
Ruf emphasizes that it is a novelty that micro-plastic concentrations can be monitored in real time. “Measuring microbial concentrations over time has never been possible before, so for the first time we can see some of the dynamic behavior, such as seasonal dependence and outflows from major rivers into the ocean,” the scientist said.
However, he noted that the fact that the model could not be validated by direct sampling of microplastics remained a serious limitation. Raf and Evans are now working on a global working group on remote sensing of marine litter and debris to improve these measurements in the future.
“It is very exciting to be involved in something new and important. This work hopefully it will lead to a stronger awareness of the problem of ocean microplastics and other marine litter and garbage, and perhaps one day a change in industrial practices and lifestyle choices that will help reduce the problem, “said Raf.
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