148 / 2022-02-27 13:03:51

Microplastics abundance and metal concentrations in Miramar beach sediments, Tamaulipas, northwestern Gulf of Mexico

Pollution,microplastic,sediments,metals

Microplastics are an anthropogenic pollutant that represents great challenge due to the complexity of the problem it generates. In the coastal environment, microplastics can act as a carrier for other pollutants, metals and persistent organic compounds, and they have the potential to modify the dynamics of interaction with the environment. Metals such as Ni, Cd, Co, Cr, Pb, Cu, and Zn have been detected in higher concentrations in microplastics than in sediment. Metals like Fe, Cu, Zn, Co, Mn, Cr, Mo, V, Se, and Ni are toxic at high concentrations, while metals like Ag, Hg, Cd, and Pb are toxic even at low concentrations. Metals can be present in both domestic and industrial drainage discharge areas. In this study, we analyzed the textural characteristics, abundance of microplastics, and metal contamination in Miramar beach sediments. The study area, Miramar beach is located in Tamaulipas State, northwestern Gulf of Mexico, Mexico. Texturally, the sediments are fine-grained size. To evaluate the concentration of metals in the sediment (As, Cr, Cu, Ni, Pb, Se, Zn), we calculated the Enrichment Factor and Geoaccumulation index, which reveals a moderate pollution. An abundance of microplastics of 4,240 pieces/kg was observed in the sediment, mostly fiber type. The most frequent colors identified are transparent, black and blue. The average length of the microplastics is 1.5 mm. FTIR analysis reveal that the composition of microplastics corresponds to the polymers: polyethylene, 6-polyamide, polycarbonate, chitosan, polystyrene, polyvinylchloride, polyethylene terephthalate, and polypropylene. Through SEM, mechanical and chemical microtextures such as grooves, fractures, adhered particles, oxidation, flakes and dissolution holes were identified on microplastics surface. Metals such as Cu and Ag were detected in microplastics through SEM-EDS. The results of this study reveal the abundance of microplastics and metals contamination in Miramar beach sediments. It is confirmed that microplastics act as vectors of metals in the Miramar beach area. This is the first study, which provides baseline information on the abundance and composition of microplastics in the Miramar beach sediments, Gulf of Mexico.