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Tourism-associated short-term variability of large microplastics on a tropical sandy beach in the Southern Gulf of Mexico

Environmental Monitoring and Assessment 2026
Moisés Vallejo Gomez, María del Carmen Cuevas Díaz, Michele Arienzo, Claudia Cucolo, Luciano Ferrara, Marco Trifuoggi, José Aurelio Sosa Olivier, José Ramón Laines Canepa

Summary

Researchers studying a popular beach in Mexico found that while total litter increased dramatically (25 times more!) during busy tourist season, the amount of tiny plastic fragments (called "microplastics") in the sand didn't change much—though the *types* of plastic shifted, with more plastic films and fibers showing up when crowds were bigger. This matters because these microplastics can end up in the ocean food chain and eventually on our plates, but the study is just a short snapshot, so more research is needed before drawing firm conclusions about tourism's long-term impact on plastic pollution.

Study Type Environmental

Tourism-associated coastal activities represent an important source of plastic-derived debris in tropical environments; however, baseline information on large microplastics (> 0.84 mm) remains limited in the Southern Gulf of Mexico. This study evaluated short-term variability in the composition and abundance of confirmed large microplastics in beach sediments from Playa Azul, Centla, Tabasco, comparing two contrasting visitation periods. Two 1-week monitoring campaigns representing low- and high-visitation conditions were conducted to assess changes in daily beach debris generation and large-microplastic characteristics. Results showed a marked increase in total beach debris during the high-visitation period, reaching values approximately 25-fold higher than those recorded during the low-visitation period. In contrast, confirmed large-microplastic abundance showed only limited short-term variation, while morphological composition differed between campaigns. Foams and fragments predominated during the low-visitation period, whereas films and fibres increased during the high-visitation period. Carbonaceous particles were recorded separately as non-plastic anthropogenic residues because their polymeric origin was not confirmed by FTIR. Polymer characterization using Fourier-transform infrared spectroscopy (FTIR) revealed high spectral matches for high-impact polystyrene (HIPS) in foams (95-98%), high-density polyethylene (HDPE) in fragments (90-95%), and polyethylene (PE) in fibres (90-92%). The Microplastic Pollution Index (MPPI) was interpreted as a descriptive screening indicator rather than as a definitive long-term pollution classification. Overall, the findings provide a short-term baseline indicating that visitor pressure was clearly associated with increased total beach debris, whereas large-microplastic abundance and morphology require broader temporal and spatial replication before robust long-term or causal conclusions can be drawn.

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