Contaminants of emerging concern, such as microplastics, have become increasingly present in coastal waters, potentially causing ecological or human health impacts. Scientists with NOAA’s National Centers for Coastal Ocean Science (NCCOS) are exploring the efficacy of using Small Intertidal Microcosm PLant Exposure (SIMPLE) Systems to investigate how microplastics divide into parts within the ecosystem and what effects microplastics and other contaminants of emerging concern have on plants and animals. SIMPLE Systems, which were developed by NCCOS scientists and a student at NOAA’s Hollings Marine Laboratory, are a series of 12 gallon buckets each with their own water inflow to mimic a more simplified version of the intertidal coastal environment and perform studies in a controlled setting.
Scientists are just beginning to study the effects of microplastics in coastal waters and ecosystems. Following the Microplastics in the Coastal Zone conference in April 2024, the need for additional microplastics studies was apparent. Throughout the conference, many experts shared their findings of the presence of microplastics and contaminants of emerging concern, but findings are limited on the effects of this pollution.
NCCOS scientists assigned 24 SIMPLE systems at random to one of six treatments–four replications for each treatment–for a 21 day exposure. The team set up each system with seawater, estuarine sediment, cordgrass plantings, juvenile clams and juvenile grass shrimp. The team conducted the experiment in a greenhouse, which receives natural light and temperature cycles with simulated tidal flux. In addition to a control, the individual treatments consisted of microcosms dosed with tire wear particles (small tire particles created from tire friction against the road that end up in the environment), 6-PPD-quinone (the chemical present in tire wear particles) perfluorooctane sulfonic acid (PFOS), microplastic beads, and a combination treatment of PFOS absorbed to microplastic beads. For this experiment, the team used crumb rubber from previously used tires with a particle size range of 63 to 150 micrometers, and fluorescent green polyethylene spheres (27-32 um in diameter).
Preliminary results indicate that PFOS that was present in seawater was transported into sediments during the 21 day exposure. The team detected 6-PPD-quinone in seawater indicating leaching from the tire wear particles in that treatment.
In the near future, the team will present the analyses of microplastic fate within the system, contaminants of emerging concern uptake, and sublethal effects in fauna. The results of this study will be used to inform the fate and transport of microplastics in estuarine systems and their potential impact to coastal species.