Study on density, shape, color, and composition of microplastics in sediments at the Han River estuary (Da Nang)

Abstract

Plastic pollution is recorded in terrestrial and aquatic ecosystems. Plastic waste exposed to the environment causes many problems for the environment and all forms of life. This study was conducted to evaluate the microplastic pollution in sediments at the Han River estuary (Da Nang). The analysis results at 8 survey locations showed that microplastics appeared in all samples and there was heterogeneity in density at 8 locations, ranging from 348.2÷3567.8 MPs/kg. Microplastic sizes in the range of 50÷150 μm account for the highest proportion with a value of 2531 MPs/kg, followed by sizes > 500; 20÷50; 50÷150, and 300÷500 μm with ratio values of 2034.2; 1292.1; 842.1, and 595.9 MPs/kg, respectively. The fibers and fragment microplastic forms accounted for most sediment samples up to 98.6%, the white color of microplastic recorded an average value of 49.8%, accounting for nearly half of the microplastics total found. FTIR spectrum shows that PET (Polyethylene Terephthalate) polymer has the highest density with 38.7%; followed by Polyester 25.1%; Nylon 12.9%; Polypropylene 5.4%; remaining polymers such as PVC (polyvinylchloride), PS (polystyrene), PE (Polyethylene), HDPE (High Density Polyethylene), etc. account for a fairly low proportion ranging from 0.7÷2.7%. This source of microplastic pollution is closely related to civil and service activities on both sides of the river. Therefore, in addition to changing environmental management measures, it is nessesary to research to understand the mechanisms that affect the transport, deposition, and interactions of microplastics with organisms living in this sediment environment.