Distribution and characteristics of microplastic deposits on sandy beaches

Abstract

This study conducts a comprehensive investigation of microplastic (MP) pollution along the São Paulo State coastline (Brazil). The primary sources of MPs are identified as inadequate plastic waste management and containment system failures in port and industrial areas. These pollutants not only compromise the natural beauty of the beaches but also negatively impact marine life by altering the physical and chemical characteristics of the beaches and impacting dependent ecosystems. The research utilized a five-step methodology comprising a geodetic survey, analysis of beach morphometric parameters, collection of beach sediments, µ-RAMAN spectrometry for polymer identification, and the application of multivariate statistical models. For MP sample collection, the coastline was divided into six segments (C1 to C6). The results indicated higher MP concentrations in C3 and C2, suggesting the influence of industrial and port activities. Various MP types, such as pellets, fragments, and fibers, exhibited distinct distribution patterns, likely due to their different sources, intrinsic properties like shape and density, and emission and deposition processes. The analysis for the entire São Paulo coast revealed that beaches with characteristics (intermediate profile and facing the southern quadrant) tend to accumulate more MPs. The predominance of polymers such as polyethylene and polypropylene reflect the influence of industrial products on marine pollution. This study highlights the complexity of MP dynamics in the coastal environment and underscores the importance of considering the physical characteristics of the beaches, the diversity of MP types, and local human activities. Identifying areas more prone to the accumulation of this emerging pollutant is critical for developing targeted environmental monitoring and remediation strategies, which align with the peculiarities of each coastal region and contribute to the Sustainable Development Goals related to ocean health (SDG – 14).