New Data on Microplastics in the Surface Waters and Sediments of the Day River Estuary, Vietnam

The estuary is an intermediate zone that receives water from various sources before flowing into the sea. Over the past few decades, plastics from river estuaries have contributed significantly to marine pollution, raising serious concerns among scientists and authorities worldwide. However, data on plastic pollution in river estuarine regions remain scarce. In Vietnam, the Day River estuary is one of the largest river estuaries flowing into the sea. The results of the present study provide new data on the density, characteristics, and distribution of microplastics in both the surface water and sediments of the Day River estuary. This estuary is heavily polluted with microplastics, with an average density of 564 ± 551.6 microplastics/m³ in the water and 3,636.3 ± 750.6 microplastics/kg in the sediments. The most common microplastic sizes ranged from 300 to 1,000 μm. These microplastics exhibit a wide range of colors, which can be classified into eight distinct groups: black, blue, gray, green, purple, red, white, and yellow. Seven of these groups (black, blue, gray, green, purple, red, and white) were found in the sediments, while six groups (black, blue, purple, red, white, and yellow) were found in the surface waters. Among these, white and black microplastics were the most prevalent in both the surface waters and sediments of the study area. The study results contribute to a more comprehensive understanding of microplastic pollution in estuarine systems in Vietnam.