RESEARCH

Plastics persist in the environment before degrading into smaller pieces called microplastics (< 5 mm), pollutants that can easily spread through the aquatic environment due to their small size, low density, and durability. Stormwater is an important conveyance mechanism for microplastics to aquatic ecosystems. Wet detention ponds are common stormwater best management practices in coastal regions that retention runoff during flashy rain events to minimize flooding and prevent pollutants from entering local waterways; however, little work has been done to evaluate their potential to retain microplastics and prevent them from being released to downstream waters. To understand how effective ponds are at retaining these pollutants, we measured the distribution and types of microplastics in the sediment of seven ponds across coastal South Carolina, USA. Based on preliminary data, the average microplastic concentration in the sediments ranged from 1.1 x 10^6 - 1.2 x 10^6 microplastics/kg of dry weight, representing some of the highest microplastic concentrations detected in pond sediments globally. Of those microplastics, rubber and polyamide (PA) were the most abundant polymer types identified through laser direct infrared (LDIR) chemical imaging. These findings will be used to create recommendations for improved pond design and management plans to improve microplastic retention from downstream waters. This research was done in collaboration with Hannah Dozier, an undergraduate researcher at Wofford College. You can learn more about her by following this link.

This work aims to evaluate the impacts of glyphosate, a commonly applied herbicide ingredient, on periphyton dynamics in residential stormwater ponds within the Grand Strand. Ponds from low- and high-density residential developments were assessed in 2024 and  2025. The concentration of glyphosate and one of its degradation products, aminomethylphosphonic acid (AMPA), along with other water quality parameters, will be measured in each pond at the beginning of the study to determine baseline concentrations and overall pond health. A passive diffusion periphytometer, housing bottles containing a gradient of glyphosate concentrations, wias deployed in each pond to measure the periphyton community response through chlorophyll-a concentration. By assessing the impacts of this herbicide ingredient on periphyton dynamics, the study will evaluate water quality and pond functionality, which will inform future stormwater pond planning and management practices.

Urban development in coastal regions introduces a number of contaminants into the environment, degrading water quality and threatening critical aquatic ecosystems. Tire wear particles (TWPs) are contaminants that shed off vehicle tires with the friction of the pavement and get carried away by wind or with rainfall from the road into adjacent waterbodies. TWPs are of particular concern because of their ability to leach n collaboratonN-(1,3-dimethylbutyl)-N′-phenyl-1,4-benzenediamine (6PPD), an additive to improve tire durability. When 6PPD reacts with gas-phase ozone, it forms a toxic transformation product called 6PPD-quinone, which has been found to be highly toxic at low concentrations to a variety of fish species. Periphyton, or the algal and microbial community that make up the base of the food web, has been widely used by aquatic scientists as a biological indicator for water quality; however, little is known about how TWPs and the additives they leach alter periphyton. This research aimed to evaluate the impacts of TWPs on periphyton dynamics in the aquatic environment. To address this, we measured the impact of environmentally relevant concentrations of TWPs using a Matlock passive diffusion periphytometer to assess the periphyton community response through chlorophyll-a concentration  during Summer 2026. The goal of this study was to evaluate how these TWPs and their additives impact the base of the food web and to evaluate periphyton’s capacity to be used as a biological indicator for TWP pollution. This work was done in collaboration with Pate Foundation Fellow Gabby Betata, who you can read more about by following this link.

Estuaries are the intersection of upland, rivers, and the sea that house a variety of unique habitats. With increasing coastal development, estuaries in the Grand Strand, South Carolina, are at risk for accumulating plastic debris, which can eventually break down into microplastics (<5mm). Murrells Inlet, SC, is characterized as an urbanized area with limited plastic policies, high rates of tourism, and high plastic consumption, making it susceptible to the influx of microplastics. In comparison, a nearby inlet, North Inlet, has little urbanization impact and limited access. We studied these two inlets to examine the impacts that urbanization has on microplastic distribution. We collected water samples at 5 different sites at each inlet (n=10) during an ebbing tide in June 2024 to analyze microplastic distributions, abundance, and composition to assess the fate and transport of microplastic pollution across these two inlets. Microplastics were analyzed and characterized on an Agilent LDIR 8700, which detected microplastics from 20-500 μm . The mean microplastics abundance across all locations in Murrells Inlet was 230.8 ± 64.77 MP/m3 while North Inlet average was 195± 78.21 MP/m3. We found that there was no statistical difference between the two inlets (p = 0.227), but patterns did emerge in distribution of abundance and particle composition across the estuaries. The most abundant particle composition was rubber, however, there was no statistical difference of rubber in these two inlets (p=0.079). Tire wear particles were most abundant in areas by boat ramps and were seen in smaller amounts in the other locations. Despite emerging similarities of microplastic abundance between these two inlets, Murrells Inlet experienced higher amounts of polytetrafluoroethylene (PTFE) (p=0.015) and polyethylene terephthalate (PET) (p= 0.054). Knowing there was limited differentiation between abundance of microplastics of pristine and urbanized inlets, these results point to a need for local mitigation and prevention efforts in order to reduce the load of microplastics into estuarine environments. This work was done in collaboration with NOAA Hollings Scholar Alyssa Wentzel, who you can learn more about by following this link.

Contaminants of emerging concern (CECs), like microplastics and pharmaceuticals, are a

growing threat to aquatic ecosystems across the globe. Microplastics can be transported into

waterways through a myriad of sources, including point sources such as wastewater treatment

plants (WWTPs) and nonpoint sources, such as runoff. The goal of this study was to evaluate the importance of non-point sources of microplastic pollution to the Huron River. To address this, I measured the microplastic load of the Huron River in Ypsilanti, MI, between September and November 2021 and May and August 2022 over a range of river discharge. There was a strong positive relationship between river discharge and microplastic load, suggesting that runoff is an important source of microplastic pollution to the river. To find out more information about this work, check out my  Master's thesis here!

Microplastics can act as vectors for other contaminants of emerging concern, such as pharmaceuticals, into biota. The goals of this study were to determine if aquatic filter feeders ingest microplastics, and how the interaction of microplastics and non-steroidal anti-inflammatory drugs (NSAIDs) affect filter feeders, using the invasive zebra mussel (Dreissena polymorpha) as a model organism. To these goals, I conducted manipulative experiments exposing zebra mussels in microcosms to microplastics and two types of NSAIDs (ibuprofen and diclofenac) in a factorial design. On average, mussels ingested 57.5 ± 35.2 MP/individual during the 24-day experiment. Results from this experiment indicate that exposure to microplastics, ibuprofen, and diclofenac for 24 days reduced mussel feeding rate in some treatments after 19-20 days but had no detectable effects on mussel growth and metabolism. To find out more information, check out my Master's thesis here!