Detection and analysis of microplastics in the subtropical ocean of Okinawa using micro-Raman Optical Tweezers

Plastic is a widely used material in our daily lives. Microplastic pollution has also generated worldwide concern due to its distribution in the environment, and its potential threat to human and animal health. Due to the complexity of sampling and extracting plastics from the marine environment, existing studies have largely focused on mesoplastics, macroplastics, and large microplastics. Having accurate methods for quantifying the abundance of small microplastics in seawater is key for defining the extent of the problem they pose. In this work, we propose a non-invasive method to analyze sub-20 μm plastics in seawater around the subtropical island of Okinawa through optical tweezers micro-Raman spectroscopy. Our results show the dominance of low-density polyethylene with highest concentrations in areas with large-scale anthropogenic activities. This study provides evidence on the presence of microplastics in ocean around a blue zone region.