Are sediment textural parameters an "influencer" of microplastics presence in beach environments?

Abstract

Diverse litter studies on Colombia's Central Caribbean Coast have presented the Microplastic issues regarding typology, magnitudes, and distribution. No studies have examined MPs' presence and abundances in relation to sediment grain size and the sediments statistical parameters (mean, median, sorting, skewness, kurtosis). This work attempts to fill this information gap in a study of 15 sampling sites along Colombia's Central Caribbean Coast. Sediment samples were collected and analysed to determine sediment granulometric properties, in association with the presence, magnitudes, shapes, and impact of MPs, and their possible relationships. Within the study area, grain size distribution was similar between surveyed sites, with a dominance of three textural groups: sands, slightly gravelly sands, and slightly gravelly muddy sands. In terms of size-sorting categories, the percentages were moderately well sorted (60%), moderately sorted (20%), well sorted (13%), and very well sorted (7%). Microplastic abundances (densities) ranged from 160 to 1120 MPs/kg, similar to other global beaches. Microplastic fibers were the dominant typology at 86.8% of the combined beaches total. Multiple linear regression analysis suggested that approximately 30% of the MPs' presence could be related to changes in the five sediment statistics used in this work, being the most important statistical parameter sorting with 11% (r2=0.27 - F-Statistic=0.67). To manage the MP issue, reducing the current elevated plastic inputs into the environment is necessary/mandatory. Approaches to reach this goal must be focused on the entire plastic life cycle (extraction, design, production, use, disposal, recovery, recycling).