Microplastics in the Watershed

While plastic pollution, such as bottles and bags littering our watershed, are easy to spot, the plastic pollution present in the Musconetcong River goes beyond what the eye can see. Smaller than 5 mm in size, microplastics are plastic pieces that can generally only be seen with a microscope. Because of their small size, finding microplastics in the environment often requires extensive sampling and analysis procedures. Microplastics are an emerging environmental concern, but up until recently, there has been little investigation into microplastics in the Musconetcong River.

the plastic pollution present in the Musconetcong River goes beyond what the eye can see

As a student at Centenary University, MWA’s Sam Johnson sought to determine how microplastics are distributed in the sediment of the Musconetcong River. In early 2021, she began her own research project at Centenary University with support and guidance from Dr. Julie LaBar, assistant professor of environmental science at Centenary University and MWA Trustee, and funded by The Independent College Fund of New Jersey. The primary goals of her project were to establish a standard operating procedure for the University and a preliminary data set for microplastics in the river. Sam sampled two sites on the river in Hackettstown and Asbury. After processing sediment samples and performing chemical analyses to separate microplastics from natural organic material, microplastics were able to be classified and counted under a microscope.

Sam Johnson collecting sediment samples at a fishing access site in Hackettstown, downstream of Dairy Queen.

From this, it was determined that there was 379 ± 50 and 264 ± 68 microplastic pieces per kilogram of dry sediment in sections of the River in Hackettstown and Asbury, respectively. The dominant microplastic type present in these sediment samples was fibers, which was expected due to their prevalence in waterways. Polyester fibers from clothes exist in wastewater from washing machines and cannot be effectively removed from wastewater treatment facilities, meaning they are released into streams.

This summer, four environmental science students from Centenary University joined Dr. LaBar’s research team to continue looking at microplastics in sediments of the Musky. These students have collected sediment samples both above and below the remnants of the Beatty’s Mill Dam in Hackettstown to determine if a gradient in microplastics concentrations in sediments exists. MWA has taken an interest in this research due to its applicability to water quality and overall stream health. Specifically, MWA is interested in how microplastics are situated in the sediment behind dams. As dam removals proceed, it is important to understand what will be released downstream.

Centenary University students Michela Sales and Anthony Ranaudo collecting sediment samples downstream of the Beatty's Mill Dam.

So far, the microplastics research happening in the Musconetcong River has only looked at how many microplastics pieces are present in the sediment. Future studies may investigate the overall fate and transport of microplastics in the stream, including the origin of these plastics, their chemical compositions, and their impact on organisms in the stream.

help prevent the introduction of microplastics into the Musky by choosing to use products free of microbeads and other plastic chemicals that can be washed down the drain

Unfortunately, efforts like MWA’s Annual River Cleanup will not rid the River of microplastics, but individuals can help prevent the introduction of microplastics into the Musky by choosing to use products free of microbeads and other plastic chemicals that can be washed down the drain. Overall, limiting plastic usage of any kind ensures that less plastic waste ends up in our rivers and streams.

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Article written by Sam Johnson, MWA Water Quality Field Specialist

For Sam's bio, visit the Our Team section of the MWA website.