Abundance, interaction, ingestion, ecological concerns, and mitigation policies of microplastic pollution in riverine ecosystem: A review

Abstract

Microplastics (<5 mm) have become an environmental hazard to natural ecosystems and humanity due to their ubiquitous presence in the environment, and possess detrimental effects on aquatic organisms. Sampling, extraction, and detection of microplastics from sediments, surface water, and biota are quite complex and challenging. Rigorous research on the abundance and distribution of microplastics in terrestrial and aquatic ecosystems is primarily attributed to instinctive anthropogenic actions like land-based activities. Although, the fate and transport of microplastics in the environment are uncertain. Therefore, this paper reviews current research progress on the occurrence and distribution of microplastic pollution in the riverine ecosystem. Detailed potential sources, sampling techniques, and experimental design have been discussed, along with the classification and detection of microplastics in the riverine sediment and surface water. Microplastic ingestion through riverine species is also discussed systematically which emphasizes the extraction of microplastics from different body parts of the organism. Different types of polymeric microplastic have been observed in rivers, for instance, PS, PE, PP, PA, PET, PVC, PDPE, LPDE, nylon, acrylic, etc. using spectroscopy. Fragments, foams, pellets, films, fibers and microbeads are common shapes of microplastic which are abundant in the riverine ecosystem. The ingestion and ecological concern of microplastics, along with adsorption mechanisms of toxic contaminants, such as heavy metals, organic pollutants, nutrients, antibiotics, etc. onto microplastics surface and their exposure to aquatic organisms have also been discussed. Microplastic pollution in riverine ecosystems is under global change stress due to ecotoxicological and geochemical consequences. Further, detailed policies intervention for plastics and microplastics mitigation have been focused which delineate for application of science and policy together with scientific evidence. Lastly, scientific knowledge gaps and future research prospective on microplastic pollution have been given, along with suggestions and policy recommendations.