Uptake and Accumulation of Nano/Microplastics in Plants: A Critical Review

Abstract

The ubiquitous presence of microplastics (MPs) and nanoplastics (NPs) in the environment is an undeniable and serious concern due to their higher persistence and extensive use in agricultural production. This review highlights the sources and fate of MPs and NPs in soil and their uptake, translocation, and physiological effects in the plant system. We provide the current snapshot of the latest reported studies with the majority of literature spanning the last five years. We draw attention to the potential risk of MPs and NPs in modern agriculture and their effects on plant growth and development. We also highlight their uptake and transport pathways in roots and leaves via different exposure methods in plants. Conclusively, agricultural practices, climate changes (wet weather and heavy rainfall), and soil organisms play a major role in transporting MPs and NPs in soil. NPs are more prone to enter plant cell walls as compared to MPs. Furthermore, transpiration pull is the dominant factor in the plant uptake and translocation of plastic particles. MPs have negligible negative effects on plant physiological and biochemical indicators. Overall, there is a dire need to establish long-term studies for a better understanding of their fate and associated risks mechanisms in realistic environment scenarios for safe agricultural functions.

Keywords: bioavailability; microbes; nanoplastics; rhizosphere; translocation.

Figure 1

Worldwide production of plastics, numbers indicate in million tons. (The data is obtained from [6]).

Figure 2

Estimates of plastic sources and transport pathways in the environment as reported in scientific literature; the data is indicated in million tons as well as the average data of high and low transportation in the ecosystem, arrows represent the known transportation and dashes represent unknown transportation in the ecosystem.

Figure 3

Plant uptake mechanism of plastic by soil application via root absorption and transport pathways from root to stem and stem transport to leaf and fruits. Foliar application reveals the entry of plastic to leaf stomata and later transfer to other parts of the plant. Cure arrow indicates the availability of plastic to plant and the dashed arrow indicates transportation within the plant.

Figure 4

Effects of MPs and NPs on plant Physiology and biochemical indicators. PS₁ represents PS (SO₃ and NH₂), PS₂ represents (COOH and NH₂), * represents g Kg⁻¹, ^ represents nm, and ^@ represents particles L⁻¹.