Non-negligible impact of microplastics on wetland ecosystems.

There has been much concern about microplastic (MP) pollution in marine and soil environments, but attention is gradually shifting towards wetland ecosystems, which are a transitional zone between aquatic and terrestrial ecosystems. This paper comprehensively reviews the sources of MPs in wetland ecosystems, as well as their occurrence characteristics, factors influencing their migration, and their effects on animals, plants, microorganisms, and greenhouse gas (GHG) emissions. It was found that MPs in wetland ecosystems originate mainly from anthropogenic sources (sewage discharge, and agricultural and industrial production) and natural sources (rainfall-runoff, atmospheric deposition, and tidal effects). The most common types and forms of MPs identified in the literature were polyethylene and polypropylene, fibers, and fragments. The migration of MPs in wetlands is influenced by both non-biological factors (the physicochemical properties of MPs, sediment characteristics, and hydrodynamic conditions) and biological factors (the adsorption and growth interception by plant roots, ingestion, and animal excretion). Furthermore, once MPs enter wetland ecosystems, they can impact the resident microorganisms, animals, and plants. They also have a role in global warming because MPs act as unique exogenous carbon sources, and can also influence GHG emissions in wetland ecosystems by affecting the microbial community structure in wetland sediments and abundance of genes associated with GHG emissions. However, further investigation is needed into the influence of MP type, size, and concentration on the GHG emissions in wetlands and the underlying mechanisms. Overall, the accumulation of MPs in wetland ecosystems can have far-reaching consequences for the local ecosystem, human health, and global climate regulation. Understanding the effects of MPs on wetland ecosystems is essential for developing effective management and mitigation strategies to safeguard these valuable and vulnerable environments.

Microplastics distribution and microbial community characteristics of farmland soil under different mulch methods.

The widespread use of plastic film in agricultural production has resulted in the accumulation of large amounts of residual plastic film in the soil, and most of the plastic residuals eventually break up into microplastics (MPs). However, the effects of different film mulching methods on the soil ecosystems are largely unexplored. Therefore, we investigated the MPs distribution and the physicochemical properties and microbial community structure in the farmland soil tillage layer covered with different mulching method of film. The results indicate that the film mulching method had no significant effect on the soil pH and organic matter content, however, the respiration intensity of the soil covered with mulching film (MF) (60.11-84.99 µg/g) and shed film (SF) (56.10-65.68 µg/g) was significantly higher than that covered with shed film & mulching film (SMF) (17.25-39.16 µg/g). The MPs abundance in the soil covered with MF (1367 particles/kg soil) was significantly higher than that covered with SF (800 particles/kg soil) and slightly higher than that with SMF (1000 particles/kg soil). The small-sized (0-0.5 mm) MPs abundance was increased with the tillage layer depth (0-20 cm), while the large-sized (1-5 mm) MPs abundance was the opposite. In addition, in the soil covered with agricultural film, the dominant phylum and genera of the bacteria were Proteobacteria (relative abundance was 64.06 %) and Pseudomonas (13.16 %), respectively. In the soil without agricultural film application as a control treatment, the diversity of the soil bacterial community was higher than that in the soil covered with agricultural film, and the relative abundances of the top 10 genera were all less than 5 %. Overall, this study provides essential information for understanding the effects of different film mulching methods on the agricultural systems. Overall, this study provides essential information for understanding the effects of different film mulching methods on the distribution of MPs and the biogeochemical properties of farmland soils.

Exogenous Glutathione Alleviates Cadmium Toxicity in Wheat by Influencing the Absorption and Translocation of Cadmium.

Cadmium (Cd), a toxic heavy metal, is harmful to plants and human health. Glutathione (GSH) could alleviate Cd toxicity of plant species, whereas its mechanism responsible for wheat remains poorly understood. Here, we found that exogenous GSH application significantly increased the fresh and dry weight, root elongation, chlorophyll contents, while decreased the contents of malondialdehyde (MDA) and GSH, and translocation factor of Cd compared with Cd treatment. Moreover, GSH application significantly increased activities of antioxidant enzymes and expression of related genes, which involved in GSH synthesis, especially in roots. In addition, we found that GSH application suppressed Cd-induced expression of metal transporter genes TaNramp1, TaNramp5, TaHMA2, TaHMA3, TaLCT1 and TaIRT2 in roots. Taken together, our results suggested that GSH could alleviate Cd toxicity in wheat by increasing GSH synthesis gene expression or suppressing Cd transporter genes expression, and further affecting Cd uptake and translocation in wheat plants.