Assessment of the water quality pollution index and ecological risk of microplastic pollution along the Tambakoso River in Surabaya, Indonesia

Increasing human activities and improper waste disposal will cause microplastic pollution in surface water. This study analyzed the abundance and characteristics of microplastics, pollution index based on water quality and its relationship with microplastic pollution, and the potential ecological risk of microplastics along the Tambakoso River which is influenced by various land uses of housing, industry, agriculture, and ponds from 16 sampling points. The average abundance of microplastics in the river was 91.80 particles/L. The Kruskal Wallis test showed that there were significant differences between microplastic pollution at each sampling location (Pvalue <0.05). In general, microplastics were mostly found in the form of fragments (48.36 %), transparent color (73.81 %), SMP size (<1 mm) (81.6 %), and dominated by PVC and nylon polymers. However, the characteristics of microplastics at each sampling location varied. The water quality pollution index value showed a slightly polluted category at most points. Redundancy analysis (RDA) showed that the characteristics of the shape and color of microplastics correlated with water quality parameters. The potential ecological risk based on microplastic pollution showed minor, moderate, and high categories at points with industrial land use. This indicates that the distribution of microplastics is closely related to human activities in the area. The level of ecological risk from microplastics depends on the percentage of each plastic polymer, along with its abundance in the environment. This study offers an important basis for designing efficient countermeasures to reduce microplastic pollution and improve water quality in surface waters.