A regional ocean circulation model coupled with a Lagrangian particle tracking model is utilized in this study to simulate the distribution and fate of floating litter particles in the Pearl River Estuary (PRE) and Northern South China Sea (NSCS) under the influence of El Nino - Southern Oscillation (ENSO) event. Simulations are conducted during all four seasons (spring, summer, fall, and winter) in typical El Niño, La Niña, and ENSO-neutral year. The model reveals that most floating litter remains within Lingding Bay before being transported westward by the counterclockwise circulation over the NSCS and arriving at the Qiongzhou Strait. After crossing the Strait, the debris is carried by the counterclockwise circulation of the Beibu Gulf, and eventually arriving at the coasts of Vietnam and Laos. The ENSO warm (El Niño) and cold (La Niña) phases disrupt circulation patterns and modulate the amount of Pearl River runoff, thereby altering the transport pathways and grounding probabilities of floating litter. During La Niña years, floating litter particles spread over a wider area, travel longer distances, and have lower beaching probabilities. Conversely, during El Niño year, floating litter particles tend to remain within Lingding Bay for longer durations, with some debris entrained towards the Hong Kong region. This study provides critical scientific insights for plastic pollution management in the PRE - NSCS region, which is a newly identified hotspot for floating litter and microplastic pollution in global oceans.

floating litter,circulation,ENSO,transport patterns,Pearl River Estuary-Northern South China Sea