Abundance, distribution, and seasonal variation of marine litter on the beaches of central Vietnam

This study investigates the abundance, distribution, and seasonal variation of marine litter across beaches in central Vietnam, using the Clean Coast Index (CCI) and Hazardous Index (HI) to assess pollution levels. A total of 16,118 litter items were recorded across 21 sampling sites, with plastics overwhelmingly dominant (96.48 %), followed by rubber (2.02 %) and paper (1.10 %), while glass, wood, and metal were minimal. The results reveal a significant seasonal influence on litter density, with higher accumulation during the rainy season due to increased runoff and riverine transport. The average litter density increased from 0.06 items/m² in the dry season to 0.14 items/m² in the rainy season (2022) and from 0.06 items/m² to 0.11 items/m² (2023). Statistical analyses using PCA demonstrated that 93.40 % of the total variance is explained by the first two principal components, highlighting the impact of seasonal and spatial pollution dynamics. HCA identified distinct site groupings based on pollution intensity, reinforcing the influence of urbanization, tourism, and human activities on litter accumulation. While most beaches were classified as "very clean to clean", urban and high-tourism areas exhibited increased pollution, emphasizing the need for targeted waste management efforts. These findings underscore the urgent necessity for enhanced waste management policies, stricter regulations on plastic usage, improved community engagement, and continuous monitoring to mitigate marine pollution and safeguard coastal ecosystems in Vietnam.