RESUMEN
Microplastics (MPs) are long-lasting anthropogenic pollutants, observed in all types of natural environments. The MPs abundance and their temporal variability in beach sands, surface waters (manta trawl), and suspended sediments (sediment trap) were assessed in Mazatlán, Mexico, a tourism destination on the northern Pacific coast, under the hypothesis that MP contamination is influenced by rainfall and population density. The MP concentrations in beach sands from urban and rural areas nearby Mazatlán (4-36 MPs m-2) and in surface waters (1.7-2.0 MPs m-3) were comparable between type of sampling sites; whereas the MP fluxes in sediment trap samples varied widely (40-782 MPs m-2 day-1) with highest values during the rainfall season. The MPs recovered were mostly white/clear (48-54%), and the prevailing shapes were fragments in beach sands and surface waters (59-80%), and fibers (75%) in suspended sediments. The synthetic polymers polypropylene, polyethylene, and polyethylene terephthalate were the most abundant in the study area.