Source, Environmental Behavior and Ecological Impact of Biodegradable Microplastics in Soil Ecosystems: A Review

Biodegradable plastics (BPs) have gained increasing prominence in the market as an environment-friendly substitute for conventional plastics, aiming to address the concerning accumulation of plastic waste in our environment. However, the notion that biodegradable plastics naturally and completely disintegrate might be misleading. In contrast, they may break down into smaller particles known as microplastics, which pose a potential threat to the soil ecosystem. This paper reviews the sources, degradation processes, transport pathways, and other environmental behaviors of biodegradable microplastics (BMPs). BMPs can affect soil quality by changing the physical and chemical properties of soil and the composition of biological communities. BMPs can also be ingested by soil organisms and thus participate in the circulation of nutrients and energy in the food web, bearing detrimental consequences for soil organisms. In addition, the toxicological effects of BMPs on ecosystems were discussed from the aspects of soil physicochemical properties and soil biomes. Not only the direct impact of BMPs, the synergistic interaction of BMPs with other soil pollutants amplifies their toxicity. Despite these insights, uncertainties persist due to limitations in analytical technology, hindering precise determination of BMPs concentrations and degradation rates in the soil environment. Moreover, understanding the concentration and residence time of additives released during BMPs degradation remains an unexplored area. Future research should emphasize long-term field trials to gain a comprehensive understanding of the extent and scope of BMPs effects on actual soil environmental toxicity.