20-2 DETERMINING WHETHER A NASHVILLE, TN WETLAND CAPTURES OR RELEASES MICROPLASTICS.

Session: Undergraduate Research

Presenting Author:

Authors:

Abstract:

The 38-acre wetland on Tennessee State University’s research farm receives storm runoff – which includes nutrients, sediments, and litter – from much of north Nashville, the research farm itself, and the campus. Every spring, student volunteers collect more than 25 large garbage bags of plastic bottles and debris along the wetland's edge, yet plastic often remains trapped in the vegetation or sitting on the bottom of the wetland. Another challenge for this wetland is harmful algal blooms caused by nutrients carried in by storm runoff. This study combines two important emerging contaminant issues facing Tennessee: 1) To determine whether the wetland is sequestering plastic or allowing it to break down into microplastics that are then released into the Cumberland River, Nashville’s source of drinking water, and 2) To determine if microplastics might be facilitating cyanotoxin transport through sorption processes. The project involved field and lab studies to address these two critical issues.  Microplastics were quantified entering and leaving the wetland by collecting at four sites along the flow path of stormwater into and through the wetland; preliminary viewing confirmed the presence of microplastic. Additional counts of microplastic suspended in water are currently underway. Microplastic and toxin concentrations in sediment were also done.  The greatest number of microplastic particles were found in 0-5 and 25-30 cm depths.  The microcystin toxin was greatest at 0-10 and 20-25 cm depths. The sorption of microcystin toxin to microplastics was conducted in the laboratory using 0.025 grams of polyethylene terephthalate (PET), filament-based plastic (FBP), and polypropylene (PP) microplastics placed in water containing 5 ppb microcystin. The PET sorbed approximately 30% of the microcystin within 24 hours. The PP sorbed 27% after 48 hours. The FBP did not sorb microcystin within the study’s 48-hour timeframe. The findings suggest the possibility that PET bottles can facilitate transport of microcystin from the wetland even if the residence time is only 24-48 hours.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

doi: 10.1130/abs/2026SE-12348

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