144-9 A Survey of Microplastics in Puerto Rican Sands using NaCl solution separation methods and Nile red optical staining

Session: Microplastics in the Environment (Posters)

Poster Booth No.: 42

Presenting Author:

Marlo Baker

Authors:

Baker, Marlo¹, Belak, Ethan², Hart, Maura³, Krekeler, Mark P. S. ⁴

(1) Department of Geology & Environmental Earth Sciences, Miami University, Oxford, Ohio, USA, (2) Department of Geology & Environmental Earth Sciences, Miami University, Oxford, Ohio, USA, (3) Department of Geology & Environmental Earth Sciences, Miami University, Oxford, Ohio, USA, (4) Department of Geology & Environmental Earth Sciences, Miami University, Oxford, Ohio, USA,

Abstract:

Plastics are a widely recognized environmental problem.The growing volume of plastics in marine environments is an issue of increasing concern. Plastics cause great harm to marine organisms through entanglement and ingestion. Furthermore, plastics break down into smaller particles, known as microplastics. Microplastics are extremely small, ranging from 1 to 5000 microns. Microplastics pass through the food chain and build up in organisms’ digestive systems leading to significant health problems. Microplastics are considered contaminants of global economic and environmental concern. Thus, identifying and monitoring the scope of the microplastic pollution crisis is necessary. Puerto Rico is an area where microplastics are comparatively understudied. Sands from three beaches in Puerto Rico were investigated for microplastic concentrations. The locations include Guanajibo Beach shore and delta, Buye Beach, and El Foro berm and shore. Sodium chloride (NaCl) solution separation methods followed by nile red staining and microscopy were used to acquire preliminary data. Approximately 30 g of dried beach sands were placed in a clean glass beaker along with about 300 mL of a sodium chloride (NaCl) solution with a density of 1.2 g/cm³. This solution was eventually filtered through a 20 micrometer cellulose filter paper, which was then examined under a dissecting microscope. This process was completed for each of the locations, and the microplastics were counted and characterized. The findings show that the average number of microplastics per kg dry weight vary amongst the beaches/locations. For Guanajibo, the average average concentration is 128 p/kg for the shore and 130 p/kg for the delta. For Buye Beach, the average items per kg is 174. For El Foro, the average items per kg is 98 for the berm and 19 for the shore. Guanajibo is a recognized site with extensive macroplastic pollution whereas the other sites are not, thus indicating that microplastic pollution may be more variable in these environments than expected. This study provides an initial survey of microplastic concentrations and serves as a comparison for future work involving more separation methods, such as zinc chloride. 

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

doi: 10.1130/abs/2025AM-8026

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