Remote sensing can help prevent plastic from reaching the ocean

Most of the plastic that pollutes our oceans comes from an unexpected source: rivers. Strangely enough, research on plastic pollution has been primarily focused on ocean environments – leaving freshwater sources a bit neglected.

Enter a team of innovative scientists from the University of Minnesota, Twin Cities, who are turning the tide with their novel research.

Published in the journal Nature, the study explores the use of remote sensing technology to monitor and remove plastic debris from rivers like the Mississippi.

Growing concern of plastic pollution

Plastic pollution in oceans has become a global environmental crisis. The United Nations Environment Program (UNEP) ranks it among the top pollution challenges of our time.

Yet, freshwater environments – rivers and lakes – have received far less attention, despite being the primary conduits for plastic waste flowing into oceans. Recognizing this gap, the researchers set out to find innovative solutions for freshwater plastic pollution.

Traditional methods of monitoring and removing plastic debris rely on manual sampling. These techniques, while effective, are time-consuming and expensive.

The new study addresses these limitations with advanced remote sensing technology, offering a more cost-effective and scalable solution.

Remote sensing to detect plastic pollution

The researchers utilized spectral reflectance properties – specific wavelengths of the electromagnetic spectrum – to detect different types of plastic debris.

By isolating the unique spectral signatures of plastics, the technology can distinguish them from natural materials commonly found in freshwater – such as sediments, driftwood, and algae.

Study lead author Mohammadali Olyaei is a Ph.D. student in the Department of Civil, Environmental, and Geo-Engineering.

“We could use this technology to identify different types of plastics in the water simultaneously. This is key information that we need when employing other technology, like drones, to capture and remove plastic debris in natural environments,” explained Olyaei.

Testing in real-world conditions

The research team conducted their experiments at the St. Anthony Falls Laboratory, where the Mississippi River flows through the facility.

This setting allowed the team to test their theories in real river conditions. They combined a remote sensing platform, called a spectroradiometer, with a digital single-lens reflex (DSLR) camera to classify and monitor various types of debris based on their spectral signatures.

This approach not only helps identify plastic debris but also lays the foundation for deploying technologies, like drones, for cleanup efforts. This dual capability of monitoring and removing debris makes remote sensing a promising tool in the fight against plastic pollution.

Broader environmental impact

Study co-author Ardeshir Ebtehaj is an associate professor in the Department of Civil, Environmental, and Geo-Engineering.

“If we can develop technology at the Mississippi headwaters, in a place like Minnesota, to catch plastic debris, we can protect the downstream states and the entire ocean from plastic pollution,” said Professor Ebtehaj.

“As soon as these plastics begin to spread more and more, their control becomes more and more challenging.”

By stopping plastics at the source, the researchers hope to mitigate the downstream effects of pollution.

The study emphasizes the importance of addressing freshwater systems to prevent plastic from reaching oceans, where it becomes far more difficult to manage.

Next steps: Scaling up the research

The team plans to expand their research to larger river systems in order to understand the movement of plastic debris across freshwater networks and to refine removal strategies.

This broader scope will also shed light on the origins of plastic pollution, which will enable more targeted interventions.

In addition to Olyaei and Professor Ebtehaj, the research team included Christopher R. Ellis, a senior research associate at the St. Anthony Falls Laboratory.

The work was funded by the Minnesota Environment and Natural Resources Trust Fund (ENTRF), a permanent fund dedicated to protecting Minnesota’s natural resources.

Importance of early intervention

The study represents a significant step forward in tackling the often-overlooked issue of freshwater plastic pollution with remote sensing.

By leveraging advanced remote sensing technology, the researchers offer a scalable, efficient solution that can benefit both local ecosystems and the global environment.

The research highlights the importance of early intervention in freshwater systems to prevent plastics from spreading uncontrollably.

With continued research and development, this technology could become a critical tool in protecting rivers, lakes, and ultimately, the oceans.

The study is published in the journal Nature Scientific Data.

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