Evaluating Microplastic Pollution in Beach Sands from the Mexican Pacific Coast: Insights from a Standardized Monitoring Approach

Supported by the Latin American and Caribbean Coastal Marine Stressors Network (REMARCO) and the International Atomic Energy Agency (IAEA), a standardized protocol for microplastic (MP) monitoring was implemented at two tourist beaches and an urbanized coastal lagoon in Mazatlán, Mexico, an area of significant tourist, commercial, and industrial activity on the northern Pacific coast. Between June 2020 and July 2021, 124 beach sand samples were collected to assess MP pollution (1–5 mm) and its temporal variability. The polymer composition of 15% of the extracted particles was analyzed using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy (Thermo Scientific Nicolet iS5). The primary types of MP identified were fragments and foam (21–41%), with synthetic polymers—polyethylene (PE; 35–44%), polypropylene (PP; 19–30%), and polystyrene (PS; 9–10%)—being the most prevalent across all sites. Additionally, cellulose (0–2%) and cotton (1–2%) particles were detected, and 14–28% of analyzed particles were confirmed as non-plastic. Thanks to REMARCO, the IAEA's RLA7028 project, and its NUTEC initiative, this monitoring program has now expanded to include additional coastal areas in the Mexican Pacific and the Gulf of Mexico, with plans to analyze smaller MPs (0.3–5 mm) in future beach sand surveys.