Seasonal analysis of microplastic concentration on the surface of the Guartinaja water body, Bajo Sinú Wetland Complex

Abstract This research focuses on characterizing the microplastics present on the surface of the La Guartinaja marsh and constructing prediction surfaces with the determined microplastic concentrations. Two field samples were taken at two different times, during rising waters (August 2023) and falling waters (December 2023), to assess the variability of concentrations at each time. Thirty sampling points were established covering the area of the marsh; the samples were processed in the laboratory with organic matter extraction and filtration, for subsequent visual analysis using a 35x stereoscope. The results obtained show variable concentrations of microplastics throughout the study area, ranging from 259.74 MPs/L for rising waters to 44.81 MPs/L for falling waters. The most abundant type of microplastic was fibers, exceeding 80% in terms of presence for both campaigns. Prediction surfaces for fibers, fragments, and total MPs were estimated using geospatial analysis techniques, which allowed for the analysis of patterns around the highest concentrations, identifying hotspots and determining spatial variability according to the study period. This research highlights the importance of studying microplastic pollution in marsh ecosystems in depth in order to preserve the health and biodiversity of these environments.