ESTIMATION OF MICROPLASTIC GENERATION FROM PLASTIC DEBRIS LITTERED ON RIVER BASIN BASED ON UV EXPOSURE EXPERIMENTS

Abstract

 The degradation degree regarding the molecular structure, surface roughness, and weight of a drinking bottle’s lib was evaluated based on the UV exposure experiment. As the lib weight decreased, the surface roughness increased. Furthermore, a significant correlation was found between the surface roughness and the ratio of the degraded lib weight to its initial weight, suggesting nano-sized plastic particles were generated from the lib surface. Therefore, a generalized linear model was constructed with UV exposure as the explanatory variable and the rate of mass loss as the response variable. Using the GLM, the annual generation of microplastics from the libs of drinking bottles littered in the river basin was estimated at 22.6 kg. This is little contribution (less than 0.01%), compared with the annual plastic waste flux from Japan, but further research on the fragmentation of macro-plastics littered in a river basin will be needed.