Large amounts of microplastic were found in the cave, which has been closed to the public for 30 years

Elizabeth Hasenmueller, deputy director of the SU Institute at the university, and her team published the results of their study in journals. Total Environmental Science And Water ResearchThey reported significant levels of microplastics at Cliff Cave in Saint Louis County, Missouri.

Microplastics are characterized by plastic particles smaller than 5.0 millimeters and can be found in marine, terrestrial and freshwater environments. Hasenmueller had previously studied microplastics in river systems such as the Meramec River Basin, but later He focused his attention on the subsoil, which has not been the subject of much study to date.

“Research on microplastics initially began in the ocean due to the visibly high problem of plastic pollution in this environment. Recently, more research efforts have been devoted to studying rivers, lakes, and other surface freshwater systems,” Hasenmueller said. said.

“One of the least studied areas in this field is the subsoil. These particles may be reaching groundwater, a common drinking water source or caves where sensitive ecosystems are located,” the scientist added.

Closed to the public since 1993

Hasenmueller and his team chose Cliff Cave for their study because the cave has been closed to the public since 1993. Allowed to eliminate human presence in the cave as a possible cause of any contamination microplastic. Their research discovered microplastics throughout the cave, but the highest concentrations were found near the entrance and in the sediments.

“One reason we chose Cliff Cave is because St. Louis County Parks regulates access to the cave,” Hasenmueller said. “We knew that if we found microplastics in the cave, it wouldn’t be because someone went there and shed fibers from their clothing or left food wrappers behind.”

Thanks to their research, Hasenmueller and his team Found that flooding increased the amount of microplastic moving through the cave systemBecause they are transported through water.

When floodwaters recede, microplastics are more likely to accumulate near the mouth of the cave than in deeper locations.

“We weren’t sure what to expect from the dataset, but here’s what we found: The main entrance of the cave is where a large amount of microplastic waste is foundIt was caused either by flood accumulation or possibly by airborne microplastic particles settling near the cave opening, Hasenmueller said.

Flood brings microplastics with it

“We know for sure that Floods bring microplastics into the cave Because as we were crossing it and collecting samples, we found a plastic bag intertwined with leaves, acorns, and other debris from surface flooding,” he explained.

Not only did the floodwaters contribute to increased levels of microplastics, but Hasenmueller and his team also They found that microplastics were almost 100 times more concentrated in the sediments than in the water found in Cliff Cave.. Microplastics were deposited in the cave sediment by water from the cave stream and remained there even after the floodwater receded.

“We were trying to determine how much of the microplastics are currently actively moving through the cave stream compared to what is stored long-term in the cave sediment,” Hasenmueller said. said. “One of the really interesting things we found was, Most microplastics were in sediment. 99 percent of the waste we found in the cave was stored in sediment; “Only a very small fraction of the plastic was in the water,” he emphasized.

“As water levels rise during flooding, you see a greater abundance and diversity of microplastic particles in the water,” Hasenmueller said. he added. “We think what probably happened is After caves are flooded, water particles settle in sedimentsanyone. As the water recedes, this material likely remains in the cave sediment for decades or longer. And when water levels drop, “microplastic concentrations in the water become much lower.”

Near a residential area

Although the cave is isolated from humans, it still suffers from their influence. Cliff Cave is located near residential areas that may contribute microplastics to the systemThis finding is consistent with previous research conducted by SLU’s SU Institute, showing that population density is the most important factor determining where microplastics are found in nature. Hasenmueller said that with these findings, there are some things people can do to limit the amount of microplastic they can contribute to the environment.

“It is difficult for us as individuals to deal with plastic pollution due to the prevalence of these materials, but it helps us to be conscious about personal use of plastic,” Hasenmueller said. “People can avoid purchasing plastic materials such as synthetic textiles used in clothingbut doing so poses a challenge for ordinary consumers. As a society, we need to move away from synthetic clothing because most of the artifacts we found in this cave were synthetic textile fibers. Of course, reducing our overall plastic production and consumption will also help.”

“Only few studies have evaluated microplastics in such underground ecosystems. Therefore, our study provides resource managers with the information they need to protect these sensitive habitats from emerging contaminants such as microplastics.”

Reference works:

DOI: 10.1016/j.scitotenv.2023.164690

DOI: 10.1016/j.watres.2023.120204

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Contact address of the environmental department:krisclimatica@prensaiberica.es