Environmental study finds microplastics in South Branch waters

Microplastics – particles so small as to be nearly invisible – are emerging as a threat to aquatic life and human health in the South Branch of the Raritan River, according to a study produced by watershed watchdog Raritan Headwaters Association.

The study was based on sampling at 10 sites along the rural river known for its clean waters, the Bedminster-based nonprofit said in a news release.

“One thing that was very striking was that every single sample we took had microplastics in it,” Kristi MacDonald, Raritan Headwaters’ science director and author of the study, said in a statement.  

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The 10 sites are along a 23-mile stretch of the South Branch between Clinton and Branchburg. Four sites were just upstream of wastewater treatment plants and four were immediately downstream of those plants.

The main purpose of the study was to find out if wastewater treatment plants are a source of microplastics in river water. The study found that microplastic concentrations were indeed higher just downstream of three of the four wastewater treatment plants.

“It indicates that water users on the sewer line, including households, businesses, schools and others, may take individual measures to decrease microplastics in wastewater,” MacDonald said. “The existence of point sources of microplastics at wastewater treatment plants provides an opportunity to target those places to minimize introduction of microplastics into the environment.”  

Health concerns

Microplastics are created by either the breakdown of larger plastic items, such as water bottles, plastic bags, food wrappers and fishing line, or the manufacture of small beads added to facial scrubs, toothpastes and cleaning products. Microplastics also include fibers from clothing such as fleece.

Concern over microplastics is growing because of potential impacts on aquatic life and human health. Microplastics can be mistaken for food by small fish and other aquatic creatures, which in turn are eaten by larger creatures and become part of the food web. Microplastics can physically harm fish and invertebrates that ingest them, and they also can carry toxic chemicals absorbed from the environment, Raritan Headwaters said.  

Microplastics, especially microfibers, have been found in drinking water supplies, including tap water and bottled water.

Raritan Headwaters’ sampling of river water took place during the summer of 2017. Fine-mesh nets were left in the South Branch for an hour at each site to collect solids drifting downstream. The nets were then taken back to Raritan Headwaters’ Bedminster laboratory, where the solids were rinsed, dried, sorted and classified.

Once organic materials and larger solids were removed from the samples, the environmental group said it was left with about 4,000 microplastic bits measuring 2 millimeters — about the size of a poppy seed — or smaller. All were logged and photographed.

The overwhelming majority were “secondary” plastics, meaning they’re degraded fragments of bags, bottles, wrappers and other plastic objects rather than “primary” plastics like microbeads from scrubbing products or microfibers from fabrics, Raritan Headwaters said.

MacDonald concluded that more study is needed to determine sources of microplastics in river water. Further study also could determine whether more microfibers and microbeads could have been found with even finer mesh nets.

“Plastics don’t go away, they just break down into smaller and smaller pieces,” MacDonald said.

Reducing plastics

According to MacDonald, the pervasiveness of secondary microplastics in the South Branch highlights the importance of Raritan Headwaters’ annual stream cleanup event, held each April.

In 2018, cleanup volunteers removed 13.5 tons of trash from river and stream banks within the watershed, including 7,643 plastic bottles and 2,688 plastic bags.

“Our annual Stream Cleanup prevented those plastic bottles and bags from eventually becoming microplastics,” she said.

The next Stream Cleanup will be April 13. Volunteers are needed. For information, visit https://bit.ly/2FoJuG2.

The pilot study also highlights the need to reduce single-use plastic bags, one of the leading contributors to microplastics pollution, Raritan Headwaters said. The state legislature is considering a bill banning single-use plastic shopping bags, as well as plastic straws and foam cups and containers, the group pointed out.

The microplastics study was funded by Raritan Headwaters and through a grant from the Rutgers Raritan River Consortium. Co-grantee, Nicole Fahrenfeld and her Rutgers University students, assisted the processing of microplastic samples.

To read the study, go to https://bit.ly/2RGT4uB.

Recently accredited by the national Land Trust Accreditation Commission, Raritan Headwaters has worked since 1959 to protect, preserve and improve water quality and other natural resources of the Raritan River headwaters region through science, education, advocacy, land preservation and stewardship. The 470-square-mile region provides clean drinking water to 300,000 residents of 38 municipalities in Somerset, Hunterdon and Morris counties.

Staff Writer Bob Makin: 732-565-7319; bmakin@gannett.com