The University of Minnesota Twin Cities scientists have developed an innovative method that uses remote sensing technology to monitor and manage plastic pollution in freshwater environments. According to their research, this approach offers a relatively cheap solution to an increasingly relevant environmental problem while revealing the behavior of plastic debris in rivers and lakes, such as in the Mississippi River.
The topic of plastic in oceans has widely been researched and focused on. The occurrence of plastics in fresh waters has comparatively seen less emphasis, although it plays a key role as a route for rivers flowing into oceans. Recognizing the significance, researchers aimed at an enhanced understanding of the control and management of plastics in rivers and lakes. It is most crucial in instances where these waters have significant value for downstream ecosystems.
The problem concerns conventional approaches to plastic removal, which are labor-intensive and time-consuming in sampling processes. Remote sensing technology could be the alternative solution. It uses the investigation of spectral reflectance properties—the specific wavelengths within the electromagnetic spectrum—to differentiate plastic materials from natural components like sediment, seaweed, driftwood, or water foam. Differentiation is key to precisely identifying and targeting plastic debris.
The research team used a spectroradiometer and a digital single-lens reflex camera to monitor and classify debris types based on their spectral signatures. These tools were tested under real-world conditions at the St. Anthony Falls Laboratory, where the Mississippi River flows through the facility. This setting allowed researchers to evaluate the technology’s efficacy in identifying and categorizing plastics amidst a mix of other natural debris.
According to the lead author Mohammadali Olyaei, the approach is versatile in the sense that it can simultaneously identify different types of plastics in freshwater environments. Such an ability is crucial for the deployment of advanced technologies, including drones, for the effective capture and removal of plastic debris.
Corresponding author of the study, Ardeshir Ebtehaj, said early intervention was the key to reducing plastic pollution. According to Ebtehaj, developing solutions at the headwaters of major rivers like the Mississippi can protect downstream ecosystems and reduce the flow of plastic waste into the oceans. Once plastic spreads extensively, its removal becomes exponentially more difficult and expensive.
The research team hopes to scale up their work to a larger scale to understand how plastic debris enters river systems, moves across them, and can be effectively removed. This knowledge may inform comprehensive strategies for mitigating plastic pollution on a global scale.
In addition to Olyaei and Ebtehaj, the study group consisted of Christopher R. Ellis, senior research associate with the St. Anthony Falls Laboratory. Their efforts were funded through the Minnesota Environment and Natural Resources Trust Fund (ENTRF), which provides for activities that preserve and protect Minnesota’s natural resources.
It provides hope that effective management of plastic pollution in freshwater ecosystems may become a reality and will not only save the habitats in a small scale but will also benefit the environment globally.