144-4 From Macro to Micro: Abundance, Sequestration, and Characterization of Microplastics in Marine Sediment from Rocky Point, Belize

Session: Microplastics in the Environment (Posters)

Poster Booth No.: 37

Presenting Author:

Emmie Rose

Authors:

Rose, Emmie¹, Lujan, Daymon Thomas², Schurr, Astrid³, Baz-Aguilar, Alessandra⁴, Hinkle, Margaret Anne⁵, Wirth, Karl R.⁶, Johnson, Elizabeth Ann⁷, Therrien, Kylie⁸, Greer, Lisa⁹

(1) Washington and Lee Univ,, Earth and Environmental Geoscience, Lexington, VA, USA, (2) Washington and Lee Univ,, Environmental Studies Program, Lexington, VA, Lexington, VA, USA, (3) Earth and Environmental Geoscience, Washington and Lee University, Lexington, VA, USA, (4) Earth and Environmental Geoscience, Washington and Lee University, Lexington, VA, USA, (5) Earth and Environmental Geoscience, Washington and Lee University, Lexington, VA, USA, (6) Macalester College, St. Paul, MN, USA, (7) James Madison University, Harrisonburg, VA, USA, (8) Earth and Environmental Geoscience, Washington and Lee University, Lexington, VA, USA, (9) Washington and Lee University, Lexington, VA, USA,

Abstract:

Studies show that microplastics are found virtually everywhere and disrupt marine and human biological processes, making it critical to understand how and where microplastics are being distributed and sequestered. This study aimed to quantify the abundance and characterize the breakdown of macro to microplastics in sediment samples from Rocky Point, an area heavily impacted by macroplastic accumulation. Thirteen sediment samples, weighing on average 626.57g, were collected along Rocky Point beach using two different methods to analyze microplastic sequestration. The top 1cm of sediment was collected using a 50x50 cm sized quadrat for 6 samples, and the top 5 cm was collected using a 25x25 cm size quadrat for 7 samples. Distance from the water’s edge was documented for each. Samples were sieved and separated into three size fractions (4.75mm, 2mm, and 212mm). Organic matter was digested using 30% H₂O₂ solution, and microplastics were suspended in a supersaturated salt solution of .3g/ml. During density separation, plastics >1mm were extracted and documented. Finer particles <1mm were decanted, filtered, and analyzed for abundance and character (size, color, and type: fragment, filament, fiber, foam or pellet). Preliminary data show an abundance of microplastics mainly in the 2mm and 212mm size fractions. Of the 13 samples, total microplastic counts range from ~40 to ~1300 microplastics, with most being clear or white fragments. A representative set of 10 macro plastics, 20 microplastics sized 1-5mm, and 7 microplastics <1mm were analyzed using a Thermo Nicolet iS50 FTIR with ATR and Continuum microscope accessories. Preliminary analyses indicated the 10 macroplastics originated from low-density polyethylene, isotactic propylene, and polystyrene. The majority of microplastics in the 1-5mm range were composed of isotactic polypropylene and high-low density polyethylene. Polystyrene and polyurethane were also found in the 1-5mm microplastics. The microplastics less than ~1mm contained polypropylene, polyethylene and rayon. Spectra of most samples indicate the presence of common dyes with peaks ~1400-1600 cm-1. Analysis of microplastics is ongoing.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7319

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