A Systematic Review of Nano- and Microplastic (NMP) Influence on the Bioaccumulation of Environmental Contaminants: Part I—Soil Organisms

Abstract

Nano- and microplastics (NMPs) are a group of contaminants that cause concern due to their abundance in the environment, high persistence, and interaction with other contaminants. This review aims to understand the role of NMP in the bioaccumulation of environmental contaminants. For that, a comprehensive literature search was conducted to identify publications that compared the uptake of contaminants in the presence and absence of NMP. In this part I, twenty-eight publications of the terrestrial compartment were analyzed. Two main taxonomic groups were studied, namely, earthworms and terrestrial plants. In earthworms, most studies observed an increase in the bioaccumulation of the contaminants, while in plants, most studies observed a decrease in the bioaccumulation. Changes in bioavailable fractions of contaminants due to NMP presence was the main reason pointed out by the authors for their outcomes. Moreover, biological aspects were also found to be important in defining how NMPs affect bioaccumulation. Dermal damage and changes in contaminant-degrading bacteria in the gut of earthworms caused an increase in bioaccumulation, and root pore blockage was a common reason for the decrease in the bioaccumulation of contaminants in plants. Nevertheless, such effects were mainly observed at high, unrealistic NMP concentrations. Finally, knowledge gaps were identified, and the limitations of this systematic review were presented.

Soil health risks caused by interactions of microplastics and pesticides

“…In Chapter 3, we observed decreased bioaccumulation of CPF in earthworm bodies with the presence of both LDPE-MPs and Bio-MPs, while this is dependent on the exposure concentrations of both MPs and CPF. This result varied from the mainstream findings which conclude that MPs can increase the bioaccumulation of contaminants in earthworm bodies (Tourinho et al, 2023). The MP size, earthworm ecotype (which can determine whether specific size of MPs can be ingested by specific species of earthworms), and exposure concentration of MPs can play important roles in contaminant bioaccumulation by earthworms (Tourinho et al, 2023).…”

“…found that the addition of PE and PVC MPs caused a shift in microbial composition towards fungi (increased ratio of fungito-bacteria), which could potentially impede pesticide degradation primarily driven by bacteria. Studies have also shown that MPs can affect the bioaccumulation of environmental pollutants, including pesticides, by soil biota such as earthworms and plants (Tourinho et al, 2023). In earthworms, some studies have observed an increase in the bioaccumulation of pesticides in the presence of MPs (Sun et al, 2021).…”

“…In plants, the influence of MPs on the bioaccumulation of pesticides has been less studied compared to other contaminants. However, it is important to note that the presence of MPs has been associated with a decrease in the bioaccumulation of contaminants in plants in general (Tourinho et al, 2023). Further research is required to gain a comprehensive understanding of the specific impacts of MPs on the bioaccumulation of pesticides in plants, particularly in relation to concerns regarding food safety.…”

“…Research on the effects of MPs on the accumulation of hydrophobic organic contaminants (HOCs) by plants is limited (Tourinho et al, 2023). Liu et al (2021) observed that the co-exposure of PE-MPs and phenanthrene decreased the accumulation of phenanthrene in wheat roots and leaves compared to a treatment with phenanthrene only.…”

“…Even though increasing studies have focused on the effect of MPs on the uptake of other contaminants by organisms (Tourinho et al, 2023), how the contaminants could ,in turn, affect the ingestion of MPs by organisms has been largely overlooked. In Chapter 3, with the adsorption of CPF, more LDPE MPs were transported into earthworm burrows with higher distribution rates of LDPE-MPs in deeper soil.…”