High surface microplastic abundance at 30°S, 90°W supports eastward extension of the South Pacific garbage patch

Abstract We conducted a latitudinal survey of floating plastic particles in the eastern South Pacific Ocean, spanning 10°S to 55°S. Samples were collected using neuston nets along 90°-100°W, providing rare data for this understudied region, including the South Pacific Subtropical Gyre (SPSG). The highest abundances were recorded at 30°S, 90°W (microplastics: 139,811 pieces km⁻² or 192,579 pieces km⁻² after correction for wind speed and wave height; mesoplastics: 30,229 pieces km⁻²), representing values one to two orders of magnitude greater than at other latitudinal sites and likely located within the convergence zone of the SPSG. The pronounced latitudinal contrasts in plastic particles detected at 30°S, 90°W as well as particle-tracking simulations based on ocean reanalysis data, corroborated earlier modeling predictions that the South Pacific Garbage Patch extends eastward to at least 90°W.