In order to achieve sustainable development goals, which direction of research or topic in the field of interaction between microplastics and soil fauna could be beneficial.
Microplastics (MPs) are emerging global contaminants, attracting more and more attention because of their difficulty in degradation, extensive and persistent pollution. In freshwater environments, especially in the ocean, they have become a global, public and even political research hotspot. However, the distribution, fate and ecological hazards of MPs in agricultural land and other soils have not been explored fully. Although the occurrence of MPs in different habitats has been reviewed at home and abroad, little attention has been paid to its environmental behaviour, ecotoxicology and interaction with biological and chemical pollutants in soil. Some studies have summarized the research progress on the source, accumulation, degradation and migration of MPs in soil, the potential risks to the ecological environment and the food chain. In order to provide a theoretical basis and practical suggestions for related research and regulatory countermeasures, the detection and treatment methods and mechanism of microplastics in soil need to be further explored.
Perhaps you can check section 6. Recommendations and future research from this recent paper by Muhammad Sajjad : Article Microplastics in the soil environment: A critical review
Elaheh Daghighi Microplastics are emerging as a steadily increasing environmental threat. Wastewater treatment plants efficiently remove microplastics from sewage, trapping the particles in the sludge and preventing their entrance into aquatic environments. Treatment plants are essentially taking the microplastics out of the waste water and concentrating them in the sludge, however. It has become common practice to use this sludge on agricultural soils as a fertilizer.