A Penn State study unveils the alarming increase in microplastics in freshwater environments since the 1950s. The research highlights the correlation between plastic production and microplastic contamination, calling for urgent action to reduce pollution.
Microplastics in freshwater environments have been on a continuous rise for decades, mirroring the surge in global plastic production since the 1950s. This troubling trend was uncovered in a significant new study by Penn State researchers, who emphasize the need for strategies to mitigate this escalating pollution crisis.
The study, led by an interdisciplinary team, sheds light on how microplastics — tiny plastic particles ranging from one micrometer to five millimeters — proliferate in freshwater habitats. The full research is available online and will feature in the December issue of Science of the Total Environment.
“Few studies examine how microplastics change over time,” corresponding author Nathaniel Warner, an associate professor of civil and environmental engineering, said in a news release. “Ours is one of the first to track microplastic levels in freshwater sediment from before the 1950s to today, showing that concentrations rise in line with plastic production.”
The researchers analyzed freshwater sediment cores from four Pennsylvania watersheds — Kiskiminetas River, Blacklick Creek, Raystown Lake and Darby Creek. Contrary to initial hypotheses, they found no significant correlation between high microplastic levels and factors like population density or land use.
“Based on other findings in the literature, what we thought would be important turned out not to be driving forces in microplastic variation across sites, notably the percentage of microplastics related to developed area and population density,” co-author Lisa Emili, an associate professor of physical geography and environmental studies at Penn State Altoona, said in the news release.
Surprisingly, while microplastic accumulation rose every decade from the 1950s to 2010, the growth rate saw a decline between 2010 and 2020.
“Although this is a preliminary finding that requires further study, this decrease could be related to increased recycling efforts,” Emili added.
The U.S. Environmental Protection Agency’s data supports this hypothesis. Recycling efforts for plastic increased significantly between 1980 and 2010, boosting the percentage of recycled plastic from less than 0.3% in 1980 to nearly 8% in 2010.
Raymond Najjar, a professor of oceanography and another co-author, pointed out that these findings might also clarify the “missing plastics” paradox, where much less plastic is found floating in the ocean than expected based on estimated input from rivers.
“This suggests that estuaries, especially tidal marshes, may trap river-borne plastics before they reach the ocean,” Najjar said.
Further research is needed to determine if these environments act as significant sinks for plastics, reducing the amount reaching the oceans.
Warner expressed concern about the health implications of microplastics, as their presence continues to grow in sediments and water.
“Humans are ingesting plastic when they eat and drink and inhaling it when they breathe, and the long-term impacts are just beginning to be studied,” said Werner.
The research team, comprising experts from multiple disciplines across Penn State, underscores the complexity and collaborative effort required for such a study.
Najjar and Warner aim to expand their research to better understand how microplastics’ composition and associated health risks have evolved over time. They also intend to further explore the role estuaries play in trapping microplastics.
This groundbreaking study not only highlights the urgent need for better plastic management practices but also sets the stage for future research into mitigating plastic pollution in freshwater and marine environments.