Abundance of non-conservative microplastics in the upper ocean from 1957 to 2066

Abstract

Laboratory-based studies have suggested that marine organisms can be harmed by ingesting microplastics. However, unless the current and future microplastic abundance in the ocean environment is quantified, these experimental studies could be criticized for using an unrealistic density or sparsity of microplastics. Here we show the secular variations of pelagic microplastic abundance in the Pacific Ocean from 1957 to 2066, based on a combination of numerical modeling and transoceanic surveys conducted meridionally from Antarctica to Japan. Marine plastic pollution is an ongoing concern especially in the North Pacific, and pelagic microplastics are regarded as non-conservative matter due to the removal processes that operate in the upper ocean. The results of our numerical model incorporating removal processes on a 3-year timescale suggested that the weight concentrations of pelagic microplastics around the subtropical convergence zone would increase approximately twofold (fourfold) by 2030 (2060) from the present condition.

The spatio-temporal distributions of these plastics are not fully characterized. Here the authors examined the sources, sinks and pathways and projected microplastic concentrations for 2066 and found that most plastics accumulate in the North Pacific, with the highest concentrations predicted in the East Asia Seas and central North Pacific.