Assessing the effects of microplastic pollution on soil and its impact on survival of earthworms and green gram plants

The major emerging threat to ecosystems and biodiversity is microplastic (MP). MPs are plastic debris of less than 5 mm in size. Among the various environmental matrices, the soil ecosystem is recognized as an important sink of MP via sewage sludge application, fragmentation of farmland plastic mulch film, compost, and aerial deposition. This study aims at examining the impacts of MP on soil ecosystems and the influence of changed soil parameters on the growth and survival of flora and fauna. The mesocosms were set up by the addition of MP, earthworms, and green gram sprouts to the soil and maintained under optimum temperature and moisture. After 30 days, the mesocosms were destructively sampled to collect soil, plant, and animal samples and to analyze their parameters. The study reveals that the addition of MP to soil had a significant impact on soil parameters. The higher values of soil aggregation suggest that the MP can cause soil clumping, paving the way for the roots to penetrate and grow faster. The resulting lower penetration resistance of the root makes it apt to absorb water and nutrients from the water, thereby increasing shoot biomass. The alkaline pH of test samples affects the growth of earthworms compared to the control. The current study's findings indicate that the presence of MPs in soil ecosystems can alter the soil physicochemical parameters, thereby influencing the growth and survival of plant and soil earthworms. This highlights the urgent need for further scientific investigation to gain a comprehensive understanding of the long-term ecological consequences associated with microplastic contamination in terrestrial environments.