Do differentially charged nanoplastics affect imidacloprid uptake, translocation, and metabolism in Chinese flowering cabbage?

Impact of nanoplastics on the biodegradation, ecotoxicity, and key genes involved in imidacloprid metabolic pathways in papyrus (Cyperus papyrus L.)

Both nanoplastics (NPs) and imidacloprid (IMI) are widely distributed in the environment and have attracted significant attention due to their adverse effects on ecosystems. Constructed wetlands have the potential to remove IMI, but there is still limited understanding of how wetland plants interact with IMI, especially when influenced by different charged NPs. This study assessed their ecotoxicological effects, as well as the fate and transformation of IMI in papyrus (Cyperus papyrus L.) under the influence of different charged NPs and identified key driving genes in the plant. Results show that simultaneous exposure to positively charged PS-NH2 and IMI inhibited plant growth. The combined action of NPs and IMI intensified their toxicity, enhancing lipid peroxidation and altering antioxidant enzyme activities. The IMI removal efficiency, which was primarily driven by biodegradation, was 80.61%, 88.91%, and 74.71% in the IMI-alone, co-IMI/PS_COOH, and co-IMI/PS_NH2 systems, respectively. PS-NH2 restricted the roots-to-shoots translocation ability of IMI. PS-COOH enhanced IMI oxidation and nitro reduction, while PS-NH2 inhibited 2-OH-IMI dehydrogenation to IMI-olefin in papyrus. Transcriptomics and gene network analysis identified the genes encoding CYP450 enzymes, reductases, hydrolases, dehydrogenases, and peroxidases as those influencing IMI biodegradation. These enzymes play a crucial role in the hydroxylation, dehydrogenation, reduction, and oxidation processes during biodegradation of IMI in the presence of NPs. This study expands the understanding of the impact of differently charged NPs on the IMI remediation efficacy of papyrus, thus providing new insights into the phytoremediation of organic contaminants in constructed wetlands.

Analytical challenges in detecting microplastics and nanoplastics in soil-plant systems

Microplastics (MPx) and nanoplastics (NPx) are increasingly accumulating in terrestrial ecosystems, heightening concerns about their potential adverse effects on human health via the food chain. Techniques aimed at recovering the most challenging colloidal fractions of MPx and NPx, especially for analytical purposes, are limited. This systematic review emphasises the absence of a universal, efficient, and cost-effective analytical method as the primary hindrance to studying MPx and NPx in soil and plant samples. The study reveals that several methods, including density separation, organic matter removal, and filtration, are utilized to detect MPx or NPx in soil through vibrational spectroscopy and visual identification. Instruments such as Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, and fluorescence microscopy are employed to identify MPx and NPx in plant tissue. In extraction procedures, organic solvents and sonication are used to isolate NPx from plant tissues, while Pyrolysis GC-MS quantifies the plastics. SEM and TEM serve to observe and characterize NPx within plant tissues. Additionally, FTIR and fluorescence microscopy are utilized to identify polymers of MPx and NPx based on their spectral characteristics and fluorescence signals. The findings from this review clarify the identification and quantification methods for MPx and NPx in soil and plant systems and provide a comprehensive methodology for assessing MPx/NPx in the environment.

Formation, behavior, properties and impact of micro- and nanoplastics on agricultural soil ecosystems (A Review)

Micro and nanoplastics (MPs and NPs, respectively) in agricultural soil ecosystems represent a pervasive global environmental concern, posing risks to soil biota, hence soil health and food security. This review provides a comprehensive and current summary of the literature on sources and properties of MNPs in agricultural ecosystems, methodology for the isolation and characterization of MNPs recovered from soil, MNP surrogate materials that mimic the size and properties of soil-borne MNPs, and transport of MNPs through the soil matrix. Furthermore, this review elucidates the impacts and risks of agricultural MNPs on crops and soil microorganisms and fauna. A significant source of MPs in soil is plasticulture, involving the use of mulch films and other plastic-based implements to provide several agronomic benefits for specialty crop production, while other sources of MPs include irrigation water and fertilizer. Long-term studies are needed to address current knowledge gaps of formation, soil surface and subsurface transport, and environmental impacts of MNPs, including for MNPs derived from biodegradable mulch films, which, although ultimately undergoing complete mineralization, will reside in soil for several months. Because of the complexity and variability of agricultural soil ecosystems and the difficulty in recovering MNPs from soil, a deeper understanding is needed for the fundamental relationships between MPs, NPs, soil biota and microbiota, including ecotoxicological effects of MNPs on earthworms, soil-dwelling invertebrates, and beneficial soil microorganisms, and soil geochemical attributes. In addition, the geometry, size distribution, fundamental and chemical properties, and concentration of MNPs contained in soils are required to develop surrogate MNP reference materials that can be used across laboratories for conducting fundamental laboratory studies.