Fayuan Wang

The widespread co-occurrence of heavy metals and nanoplastics (NPs) in soil poses persistent stress to rhizobia.

Both biochar and nano-zero-valent iron (nZVI) are increasingly used to remediate soils polluted with heavy metals, such as the toxic Cr(VI). However, how soil microbiomes respond to biochar and nZVI applied in Cr(VI)-contaminated soil has not yet been clarified. The current study compared the effects of bare nZVI (B-nZVI) and starch-stabilized nZVI (S-nZVI) at 100 and 1000 mg/kg on soil enzyme activity and microbial communities in Cr(VI)-contaminated soil growing mung bean amended with or without 1% biochar. High-throughput metagenomic sequencing was conducted to determine the evenness (Simpson index), diversity (Shannon index), and richness (Chao-1 index) of soil bacteria, fungi, archaea, and viruses. Soil catalase activity was inhibited by S-nZVI but stimulated by biochar. Soil phosphatase activity was stimulated by both types of nZVI, but not influenced by biochar. The combination of 1000 mg/kg nZVI and biochar decreased bacterial and fungal evenness and diversity, but did not significantly alter their richness. Archaeal communities remained relatively stable across most treatments. The evenness and diversity of viral communities increased significantly at 1000 mg/kg S-nZVI, whereas the richness decreased conversely. PCoA showed that soil microbial community structure was significantly changed by 1000 mg/kg S-nZVI, which diminished Actinobacteria but enriched Cellvibrio. Furthermore, 1000 mg/kg S-nZVI increased the abundances of some genes involved in antioxidant enzymes and the metabolism of Fe and Cr, and decreased the abundance of C-cycling genes significantly. Overall, S-nZVI caused significant perturbations in soil microbial activity and community structure, but these adverse effects were alleviated by the incorporation of biochar.

Microplastics (MPs) and nanoplastics (NPs) have emerged as pervasive contaminants across diverse environments—including soil, water, and the atmosphere—posing substantial risks to resident organisms. Concurrently, alien plant invasion represents a significant driver of environmental change, introducing considerable ecological risks to terrestrial ecosystems. Synthesizing evidence from 26 original research articles, this review examines the bidirectional interactions between micro(nano)plastics (MNPs) and terrestrial invasive plants. A growing body of evidence indicates that MNPs alter the growth and performance of both invasive and native plants. In most documented cases, MNPs appear to enhance the competitive ability of invasive plants, thereby elevating their invasion potential. However, counterexamples exist wherein MNPs strengthen the competitiveness of native plants, consequently mitigating invasion risk. These divergent outcomes are likely attributable to a suite of influencing factors, notably the characteristics of the MNPs (e.g., type, size, concentration), the specific invasive and native plant species involved, and variations in experimental conditions. Key mechanistic pathways involve MNPs-induced disturbances in soil microecology—particularly nutrient dynamics and rhizosphere microbiomes—and allelopathic interactions. Conversely, invasive plants may adsorb/absorb MNPs and subsequently modify their environmental fate and behaviors (e.g., degradation, transport). Finally, we delineate critical knowledge gaps and propose prioritized directions for future research. This review advances our understanding of the ecological risks associated with plant invasions in an era of pervasive MNP pollution and offers a scientific foundation for developing informed management strategies.

Microplastics can be absorbed by plant roots and enter the food chain. Throughout the plant life cycle, roots frequently encounter various physical injuries. However, whether these prevalent injuries serve as critical pathways for microplastics entry into plants remains unknown. Here, we demonstrate that both shallowly wounded roots (injuries limited to the cortex) and unwounded roots exhibit effective resistance to the penetration of microplastics. In contrast, deep wounds (injuries extending to the stele) in roots provide a rapid pathway for microplastics to enter crops such as taro (Colocasia esculenta) and maize (Zea mays). Microplastics are rapidly transported upward via wound-exposed xylem vessels in both vermiculite and soil culture conditions. When 20% of the roots were subjected to deep wounds and exposed to vermiculite containing 50 mg kg^-1 of polystyrene microplastics, the accumulation levels in taro corms reached 161.1 ± 26.4 (1 μm) and 135.6 ± 24.9 (5 μm) items g^-1, while in maize stems reached 503.4 ± 147.4 (1 μm) and 222.3 ± 63.8 (5 μm) items g^-1. Our findings provide substantial evidence that root wounds facilitate the uptake, translocation, and accumulation of microplastics in crops, underscoring the urgent need for proper farming practices to prevent root injuries and enhance food safety.

Sweet sorghum has a high tolerance to toxic metals, but its response to soil amendments in Cd-polluted soils remains underexplored. Here, we compared the effects of biochar and hydroxyapatite (HAP) at different doses (0, 0.5%, and 1%, w/w) on the growth, mineral nutrition, stress tolerance, and phytoremediation efficiency of sweet sorghum grown in an agricultural soil heavily polluted by Cd (20.80 mg/kg). In most cases, both amendments greatly increased plant biomass and nutrient uptake of N, P, and K, and enhanced the activities of antioxidative enzymes (peroxidase and superoxide dismutase) in leaves. They also increased soil pH and reduced soil available Cd concentrations, confirming their liming effects and immobilization of Cd. Unexpectedly, both HAP and biochar significantly increased Cd concentration and uptake in the shoots and roots, contradicting prior findings. Shoot Cd uptake was increased by 96% and 57% by 0.5% and 1% biochar, respectively. Root Cd uptake was increased by 50% and 64% by 1% HAP and 0.5% biochar, respectively. Overall, both HAP and biochar improved sweet sorghum growth and mitigated Cd toxicity, and particularly, decreased soil Cd availability while enhancing shoot and root Cd accumulation, indicating a promising strategy for the phytoextraction and phytostabilization of Cd-polluted soils.