ST. LOUIS – For those interested in understanding the impact of human activities on our environment, Saint Louis University has recently published a report on Cliff Cave. This report highlights the findings of a research team that found the presence of microplastics within a cave that had been sealed for the past three decades. 

A biologist looks at microplastics found in sea species at the Hellenic Centre for Marine Research near Athens, on November 26, 2019. – “Marine litter is a global issue, so it is (present) in Greece. More than 70 percent of marine litter is plastic in Greece,” says Katerina Tsagari, a biologist .The team has found litter, most of it plastic, in about 75 percent of loggerhead turtles tested. Overall, they have found plastic ingestion in between 20 and 45 percent of the species tested, which include fish, crabs and mussels. (Photo by LOUISA GOULIAMAKI / AFP) (Photo by LOUISA GOULIAMAKI/AFP via Getty Images)

In two recent papers, SLU reported the discovery of high concentrations of microplastics in Cliff Cave, located in St. Louis County. This cave has remained sealed off from human exposure for the last 30 years. Elizabeth Hasenmueller, Ph.D., a professor of Earth and Atmospheric Sciences and associate director of the WATER Institute at SLU, led the research team that found plastics in both the water and soil within the cave.

Microplastics, which are plastic particles smaller than 5.0 millimeters, can be found in various environments, including marine, terrestrial, and freshwater settings. While Dr. Hasenmueller had previously studied microplastics in river systems, such as the Meramec River basin, she was eager to explore the subsurface, an area that has received limited research attention.

Dr. Hasenmueller explained in the article her choice of Cliff Cave: “Part of the reason we selected Cliff Cave is that St. Louis County Parks regulates access to the cave. We knew that if we found microplastics in the cave, it wouldn’t be due to individuals hiking back into the cave and unintentionally leaving fibers from their clothing or food wrappers.”

One possible source of the plastic is flooding. Water can transport microplastics, and during flooding events, extra water may carry more microplastics into the cave.

The cave is also located near residential areas, which can also be a contributing factor for the plastics. Microplastics can harm Cliff Cave fauna and the cave habitat. Bats, amphibians, and other creatures roam the cave, and microplastics could damage their ecosystem. Microplastics are a human and environmental issue, and Hasenmueller wants more studies to prevent contamination.