Preliminary study to characterize microplastics in the coastal environment using multiple analytical approaches

Battulga, B. ; Atarashi-Andoh, Mariko  ; Koarashi, Jun   

Plastic debris has been recognized as an emerging contaminant in the global ecosystem. Although microplastics (MPs) have received special attention from the scientific community owing to their widespread distribution, application of highly sensitive techniques to evaluate the characteristics of MPs is still under consideration. In this study, we demonstrate multiple analytical approaches including microscopic, spectroscopic, and isotopic analyses to track MP characterization obtained from coastal river environment. We selected two sampling sites from coastal areas in Japan and collected visible plastic samples. At the same time, surface water and coastal sand samples were collected to evaluate the seasonal variations in MP occurrence and composition. Seasonal differences in occurrence and morphotypes of MPs were detected in both sampling sites, suggesting variations in geographical patterns and consumption of plastic materials in the studied region. We also found differences in carbon isotopic composition between the MPs composed of the same polymer (i.e., polyethylene and polypropylene) but with different colors. Preliminary results of Cs activity concentrations revealed that plastics serve as carriers for radionuclides mediated by biofilms in the coastal river environment. Furthermore, occurrences and differences in the composition of the MPs in the study areas indicate that point and nonpoint sources of MPs strongly affect their concentration in the aquatic environment.