The researchers outlined the relationships between microplastic levels found in the sediment samples, visualizing the difference in plastic content from data taken upstream to samples taken downstream. They then compared this information to existing readings taken from 17 other countries, capturing insights on the environmental factors that influence microplastic concentration and movement around the world. <\/p>\n
The team found that watersheds located in regions with higher population densities, or adjacent to wastewater treatment plants and agricultural land, exhibited higher concentrations of microplastics. In contrast, regions with more forestry and vegetation coverage tended to display lower concentrations. Freshwater in the mid-Atlantic displayed lower overall levels of microplastics compared to readings taken from other watersheds internationally, including sites in Europe and Asia, but higher concentrations than other North American countries, like Canada or Mexico. <\/p>\n
Not all the data answered questions \u2014 some raised new ones, Warner said. The team identified that the headwaters of a watershed did not consistently display lower concentrations of microplastic content compared to areas distanced farther downstream, which tend to be in more densely populated areas. Warner explained this suggests local features are more critical in determining microplastic content than previously thought. <\/p>\n
For example, samples collected from a rural watershed in Raystown, a forest-heavy region in central Pennsylvania, exhibited similar microplastic levels to samples taken from John Heinz National Wildlife Refuge, a watershed located close to the Philadelphia International Airport. According to Warner, these findings reinforce that the prevalence of microplastics cannot be solely predicted by factors as simple as proximity to population centers, location in the watershed or vegetation density. <\/p>\n
\u201cWe are still trying to figure out exactly why this is,\u201d Warner said. \u201cRaystown is an area heavily used for camping and recreation, so that could play a role. The data illustrates that there\u2019s a combination of different factors at play, which we hope further studies will help us better understand.\u201d <\/p>\n
The team said this study will serve as a basic framework to better understand how microplastics move across the environment, as well as how human activity influences buildup. They plan to further investigate the types of plastic found across Pennsylvania ecosystems and the risks they pose to communities that use these watersheds as a source of drinking water. <\/p>\n
\u201cWe are asking a lot of questions to better quantify the risks,\u201d Warner said. \u201cWhat type of plastic is it? How big is the plastic? Is it a risk to humans or the aquatic life in an ecosystem? Although all of these materials are microplastics, some plastics are smaller than others and more harmful, and some types of plastic are much more toxic when ingested than others.\u201d <\/p>\n
Additional contributors affiliated with Penn State include Jutamas \u201cJudy\u201d Bussarakum, an environmental engineering doctoral candidate and first author on the paper. <\/p>\n
This work was supported by the U.S. National Science Foundation. <\/p>\n
At Penn State, researchers are solving real problems that impact the health, safety, and quality of life of people across the commonwealth, the nation and around the world. <\/p>\n
For decades, federal support for research has fueled innovation that makes our country safer, our industries more competitive and our economy stronger. Recent federal funding cuts threaten this progress.\u202f\u202f <\/p>\n