Spatial Distribution of Microplastics in Mangrove Sediments of a Polluted Embayment in the Eastern Tropical Pacific

For 2 years (2018 and 2021), we studied the presence of microplastics (g) in four sampling stations in intertidal mangroves in Buenaventura Bay, Colombian Pacific. The sediments were extracted using the flotation method and then counted and characterized according to their particle shape and size. We analyze these results using descriptive statistics and a hierarchical model. We found microplastic particles in all sediment samples, with an increase in the average amount of microplastic particles from year to other. Significant differences were found between years and sampling stations, and no significant differences in average microplastics were found in relation to plot location and depth. However, in terms of the spatial distribution of microplastics, a greater accumulation of microplastics was observed in the outer plots located at the edge of the tidal line (forward position). Regarding the vertical distribution of microplastics, a descending accumulation gradient was not observed, as expected. The most relevant particle shape among the microplastics was the fiber (95.75%) and the transparent color was predominant among the identified particles (64%). It is likely that the presence of microplastics is due to the poor management of wastewater and solid waste, resulting in the degradation of marine plastic waste accumulating in mangroves.