Qianqian Yu

Microbially mediated manganese (Mn) biomineralization is crucial for environmental redox buffering and metal cycling, but its response to nanoplastic (NP) pollution remains unclear. Here, the Mn(II)-oxidizing fungus Acremonium strictum KR21-2 was used to evaluate NP effects across a wide concentration gradient. Across all NP treatments, fungal dry weight decreased by less than 20%. Moreover, NP exposure reprogrammed fungal metabolism and gradually remodeled bound extracellular polymeric substances (B-EPS). At low doses (1 and 10 mg/L), NPs redirected cellular metabolism toward glycolysis and biosynthetic pathways and promoted the accumulation of polysaccharide (PS)-rich B-EPS. This adaptive extracellular matrix maintained Mn(II) oxidation while modifying the extracellular nucleation microenvironment, thereby enhancing the crystallinity of birnessite-like biogenic Mn oxides. At 50 and 100 mg/L NPs, B-EPS underwent further functional remodeling, characterized by protein (PN) enrichment, elevated PN/PS ratios, and extracellular superoxide accumulation, suggesting a transition toward an oxidatively stressed microenvironment. This remodeling, in conjunction with suppressed Mn-oxidizing enzyme expression, resulted in the loss of Mn(II) oxidation. These findings indicate that B-EPS forms a crucial yet delicate regulatory network that connects intracellular metabolic reprogramming to extracellular Mn(II) oxidation. B-EPS is sensitive to low-dose NP perturbations, undergoing substantial alterations before the inhibition of Mn biomineralization. Considering that Mn biomineralization is a typical biologically induced mineralization process regulated by the extracellular microenvironment, even minor changes in B-EPS may be magnified and significantly influence the biomineralization pathway and product structure. Therefore, risk assessments based solely on organism-level toxicity may underestimate the ecological impacts of NPs.

Traditional nanoscale zerovalent iron (nZVI) plays a crucial role in combating solid emerging pollutants. This study demonstrates that nZVI can effectively facilitate the aging and dechlorination of polyvinyl chloride (PVC) microplastics under mild anaerobic conditions. The effects of common heavy metals on the dechlorination aging process showed a dechlorination efficiency ranking of Ni > Cu > Co > Cr. Ni²⁺ and Cu²⁺ promote electron transfer and the formation of active iron phases by generating active metallic sites, while the catalytic efficiency of Cu is regulated by the redox cycle between Cu⁺ and Cu²⁺. In contrast, Cr⁶⁺ significantly inhibits dechlorination due to the formation of passivation layers. Electron transfer capacity was identified as the critical driving force for dechlorination, with Ni²⁺ exhibiting the highest electron donor and acceptor capacity. The dechlorination process was accompanied by C-Cl bond cleavage and the formation of C═C groups, indicating that chain scission and carbon backbone rearrangement are key reactions. However, the sequence of bond cleavage and formation varied among different metals. Additionally, in high-efficiency aging systems, more short-chain compounds were produced alongside long-chain compounds, indicating that synergistic effects between metals and nZVI promoted the molecular transformation of PVC chains.

Biogas residue (BR) and biogas residue‐derived biochar (BRC) are widely used as substitute for inorganic Nitrogen (N) fertilizers in vegetable production. Yet, their comparative research on vegetable production and N₂O production was still lacking. Here, the pot experiment of pakchoi (Brassica chinensis) with a gradient of BR or BRC application rates (0, 30%, 60%, 100% w/w) was carried out to simulate different N fertilizer substitution rates. The results showed that the pakchoi yield had no difference between BR or BRC and control treatments; BRC had more advantages than BR in maintaining or increasing the pakchoi yield. BR and BRC could all reduce N₂O production potential in vegetable soils. But BRC had a stronger ability to inhibit denitrification while BR had a stronger ability to inhibit nitrification compared with each other. The results showed that BR and BRC had different regulatory pathways for pakchoi yield and N₂O production. BR regulated the pakchoi yield majorly through nitrification, but BRC majorly through denitrification. It suggested that BR and BRC could partially or completely replace inorganic fertilizers without reducing pakchoi yield. BRC combined with chemical fertilizers was a higher intelligence strategy in vegetable systems to improve pakchoi yield and N₂O production compared with BR. It provided a theoretical basis for the application of BR and BRC to nutrient cycling and microbial processes in the soil‐vegetable system.

As industrial waste from aluminum production, red mud (RM) poses a severe threat to the local environment that needs to be appropriately utilized. The activation of iron oxide, which is abundant in RM, improves its effectiveness as a catalytic material for the degradation of organic pollutants. This study developed a novel activation approach by adding dithionite citrate bicarbonate (DCB) for Bisphenol A (BPA) degradation under aeration conditions. Electrochemical experiments and reactive oxygen species (ROSs) trapping experiments showed that DCB treatment enhanced the redox cycle of Fe(II)/Fe(III), which promoted free radical generation. The optimized condition for the RM activation was achieved at 21 mmol/L dithionites, 84 mmol/L citrates, and 34 mmol/L bicarbonate, and the degradation of BPA by activated RM reached 410 mu g BPA per gram of RM. This work provided a feasible way to utilize RM resources as an efficient, low-cost catalyst for organic pollutants treatment.