Microplastics distribution in the soil: A review

Abstract

The pervasive use of plastics in modern society has led to significant environmental concerns about plastic pollution. As demand for plastic materials continues to rise, the improper disposal of plastic waste poses a substantial threat to both marine and terrestrial ecosystems. Microplastics, defined as plastic debris <5 mm in diameter, have emerged as a contaminant of global significance. While extensive research has focused on microplastic pollution in oceans, the impact on terrestrial environments remains understudied. The heterogeneous distribution of microplastics raises concerns about soil health, nutrient cycling, and crop productivity. Microplastics are not uniformly distributed across soil profiles. Instead, they often accumulate in topsoil layers where they interact with plant roots, microorganisms, and soil fauna. Their presence has been linked to changes in soil structure, reduced water holding capacity, and disruptions in microbial community dynamics. Understanding the patterns, pathways, and mechanisms governing microplastic distribution is therefore critical for developing informed mitigation strategies. If the food chain is disrupted, it can have negative impacts on soil biota, raising worries about human health. In this review, microplastics’ impacts on soil biogeochemistry and their interactions with soil organisms are discussed, along with their properties, research trends, and other factors. Recent findings suggest that soil serves as a primary sink and transporter of microplastics, which can then enter aquatic ecosystems and affect soil biota, potentially disrupting the food chain and human health. We emphasize the need for ongoing study into the impact of microplastics on terrestrial ecosystems.