Distribution of floating inertial particles in the ocean by their density: formation and evolution of the Great Pacific Garbage Patch

A significant amount of man-made garbage is accumulating in the ocean, particularly plastic debris, which is hard to break down. Efforts have been made to estimate the amount of garbage, locate the areas with the highest accumulation, and clean it up. However, the problem is still growing. Our study utilized the Maxey-Riley equations for inertial particles in the air-sea interface to investigate how debris accumulates and spreads in the North Pacific Ocean. The particles are spherical and can have a density different from that of water or air. We studied the particles' motion based on their density. Our findings show that the heaviest particles, with a density just below the seawater density, tend to gather in the Great Pacific Garbage Patch (GPGP). The less-dense spheres accumulate in smaller quantities in the GPGP and are carried westward; some of them are beached on the coasts of Asia. Furthermore, we reproduced an accumulation of garbage in the Gulf of Alaska, where previous observations report relatively high concentrations of micro- and mesoplastics relative accumulation. Our results show that the Maxey-Riley equation for particles in the air-sea interface is an effective tool for carrying out and optimizing actions to clean up floating debris pollution in the ocean. Finally, we observed a seasonal pattern in the location and dispersion of the GPGP. It was previously noticed that there is a seasonality linked to the weakening of the atmosphere's anticyclonic circulation over the Pacific Ocean. We reaffirm that in some winters, the particles leave the location of the GPGP.