Researchers from Asahi Kasei Corporation and Kyushu University have developed a novel technique to estimate the age of microplastics in the ocean, showing that nearshore microplastics can be between 0 to 5 years old, while offshore samples range from 1 to 3 years old. Microplastics, defined as plastic fragments less than 5 mm in length, are a prevalent form of marine pollution. This new method combines plastic oxidation analysis with environmental factors such as UV exposure and temperature. The team conducted exposure experiments on polyethylene, the most common plastic, to understand how these factors affect degradation, measuring molecular weight and the carbonyl index as indicators.
Their findings reveal a significant correlation between UV radiation and seawater temperature with degradation rates. They collected samples from various locations in the North Pacific and found that nearshore fragments have a longer age range due to frequent coastal washing and sustained exposure, while offshore samples tend to be younger. This research aims to improve understanding of microplastic generation and distribution and enhance modeling efforts to track plastic pollution in marine environments. The study, published in the Marine Pollution Bulletin, marks a step toward elucidating the environmental impacts of microplastics.
