Microplastic-derived dissolved organic matter (MP-DOM) is an emerging class of dissolved organic matter in the environment, yet how it reacts with heavy metals and affects their species remains poorly understood. This study investigates the Cu2+ binding and Cr6+ reduction potential of DOM released from polystyrene (PS), polypropylene (PP), and polybutylene adipate terephthalate (PBAT) under both dark and solar irradiation. The fluorescence quenching method, combined with excitation-emission matrix-parallel factor analysis (EEM-PARAFAC), was used to evaluate metal interactions, revealing that plastic-derived humic like fluorescent components exhibited substantial quenching with increasing Cu2+ concentration. Stability constants (log KM) were higher under solar irradiation (1.59-3.32) than in the dark (0.36-2.22), confirming weaker to moderate complexation under light exposure. Solar irradiation shows almost same findings of Cr6+ reduce during 10 min, achieving 94-99% reduce with first-order rate constants (k) of 0.53-0.57 min(-1), compared to 86-99% reduce (0.49-0.58 min(-1)) under dark conditions, the statistical analysis shows non-significant change (p > 0.05). Two-Dimensional Correlation Spectroscopy (2D-COS) based on FTIR suggested that oxygen-containing functional groups generated by solar irradiation contributed to higher metal-binding and reduction affinity. These results demonstrate that MP-DOM not only forms stable complexes with Cu2+ but also acts as a potent reducing agent for Cr6+, highlighting the critical role of MP-DOM in governing the fate and toxicity of heavy metals in aquatic systems.

Microplastics (MPs) persist in the environment due to their chemical inertness and structural stability, underscoring the need for effective degradation strategies. Here, we develop a surface-confined cascade system in which laccase is coupled with metal ions (Na+, Cu2+, Fe3+) to activate reactive oxygen species (ROS) for the degradation of three representative polymers─polyethylene (PE), polyethylene terephthalate (PET), and polylactic acid (PLA). The laccase-Cu2+ system (optimal at 0.1 mM) exhibited the strongest catalytic performance, inducing substantial oxidative transformation of MPs, as reflected by pronounced increases in O/C ratios and extensive disruption of polymer surface chemistry. Among the three polymers, PLA showed the highest degradation susceptibility owing to its lower crystallinity, labile aliphatic ester linkages, and enhanced responsiveness to ROS. In situ-generated MPs-derived dissolved organic matter (MPs-DOM) further regulated interfacial redox processes by accelerating electron transfer to metals, stabilizing reduced species, and sustaining ROS cycling. XPS and solution-phase analyses corroborated the DOM-assisted metal redox cycling at polymer interfaces. Multivariate modeling identified humic-like components and oxygenated moieties as the dominant ROS predictors. These findings reveal MPs-DOM as an active redox mediator that reinforces laccase-metal synergy, enabling persistent ROS generation and progressive MPs degradation.

Global municipal solid waste (MSW) incineration faces escalating environmental risks from polycyclic aromatic hydrocarbons (PAHs) due to increasing plastic content, yet the specific role of plastics remains poorly understood. Hence, this study systematically characterized PAHs EFs and distribution profiles during MSW combustion across a range of temperatures (300 - 900 °C) and plastic mass fractions (Mpc, 15.43% - 63.43%), while the transition in PAHs formation pathways was elucidated using density functional theory (DFT) calculations. Results demonstrated that Mpc significantly increased ∑PAHs EFs (3.41-7.63 g/kg) and altered pPAHs distribution (87.98-93.14%), explaining 45.78% of the variance. This alteration featured the shift in predominant product of six-ring indeno[1,2,3-cd]pyrene (IdP) to five-ring benzo[k]fluorene (BkF). In contrast, combustion temperature (21.02% of variance) affected only the EFs (2.18-5.13 g/kg) with negligible distribution changes (<0.38%). DFT calculations demonstrated that the shift in the dominant reaction pathways during high-plastic combustion is driven by the accumulation of intermediate acetylene, which triggers a mechanistic transition from the hydrogen abstraction-vinylacetylene addition (HAVA) pathway to the hydrogen abstraction-acetylene addition (HACA) pathway. Among seven polymers, PVC showed the strongest promotion of PAHs formation, and this effect was further amplified in mixed-plastic systems, where experimental EFs exceeded theoretical values by up to 34.95-fold, indicating complex radical-chain interactions during co-combustion. The proposed BkF/Perylene ratio performed a robust molecular tracer, stable across thermal fluctuations yet highly sensitive to plastic-to-cellulose ratios. These findings clarify plastics' role in PAHs formation during MSW combustion and support optimized incineration strategies for plastic-containing waste.

Microplastics (MPs) present a significant environmental challenge due to their widespread contamination and inherent resistance to biodegradation. Enzyme-driven biodegradation has emerged as a promising and environmentally friendly approach to mitigate microplastic pollution, yet the underlying molecular mechanisms remain poorly understood. This study systematically explored the laccase-mediated degradation of aliphatic (polyethylene, PE), aromatic (polyethylene terephthalate, PET), and biodegradable (polylactic acid, PLA) MPs, aiming to uncover the molecular-level mechanisms driving these processes. Our results demonstrated that laccase selectively degraded these MPs into low-molecular-weight products through polymer chain scission and functional group transformation. Notably, PLA exhibited the highest degradation efficiency, evidenced by significant surface modifications and molecular weight reduction. Reactive oxygen species (ROS) generation and electron-transfer processes were found to facilitate polymer chain cleavage and functional group evolution. Molecular dynamics simulations revealed distinct binding modes of laccase with different MPs: hydrophobic interactions dominated with PE, while hydrogen bonding and electrostatic forces played crucial roles with PET and PLA. These findings provide molecular-level insights into laccase-mediated MP degradation and offer valuable guidance for developing sustainable enzymatic strategies to tackle plastic pollution.

The adverse effects of microplastic particles on plant growth have been extensively studied, but the ecological risks caused by microplastic-derived dissolved organic matter (MP-DOM), which is substance continuously released from microplastics and highly bioavailable, still remain largely unexplored, especially its toxic effects and underlying mechanisms on plant growth. Here, we employed multiomics combined with transgenic materials to investigate the effects of different MP-DOM types, including PP-DOM, PS-DOM, and PBAT-DOM, on Arabidopsis root growth. The results indicated that PS-DOM and PBAT-DOM, but not PP-DOM, significantly inhibit root elongation in a dose-dependent manner by impairing the meristem zone and stem cell activity. Integrated transcriptomic and metabolomic analyses revealed that MP-DOM altered gene expression related to phenylpropanoid biosynthesis and the plant hormone signal transduction pathway. Molecular transformation network analysis revealed that low-polarity saturated molecules enriched in PS-DOM and PBAT-DOM perturbed the phenylpropanoid biosynthesis, thereby indirectly impairing auxin homeostasis. Phenotypic analysis of auxin reporter lines confirmed that PS-DOM and PBAT-DOM disrupt polar auxin transport by downregulating the expression of auxin transporters, leading to abnormal auxin accumulation and inhibition of root growth. This study elucidates the molecular mechanism underlying MP-DOM-induced phytotoxicity, providing insight into the ecological risk assessment of microplastics in agricultural production.

Nanoplastics, commonly found with varying charge states in the environment, represent an emerging pollutant with the potential to be absorbed by terrestrial plants, negatively affecting their growth, especially root growth. However, the underlying mechanisms by which surface charge modifications affect root growth remain poorly understood. We investigated the impact of polystyrene nanoplastics with different surface charges on the growth and development of roots, and identified the cellular response pathways triggered by nanoplastics and molecular mechanisms with the help of transcriptomics sequencing, confocal microscopy observation, and molecular docking simulation. The results showed that strong inhibitory effects of negatively charged nanoplastics on development of root meristem zone. Additionally, it downregulated genes associated with stem cell niche activity and mitotic processes. Transcriptomic analysis highlighted the significant suppression of key pathways related to phytohormone signaling and transmembrane transporter protein activity. Molecular docking further demonstrated that negatively charged nanoplastics preferentially bind to polar auxin efflux transporter PIN proteins, leading to excessive auxin accumulation at root tip and impairing auxin redistribution, thereby disrupting gravitropic growth. This research offers valuable insights into how differently charged nanoplastics influence root growth and provides guidance for the ecological risk assessment of nanoplastics and the sustainable development of agriculture.

The widespread occurrence of microplastics (MPs) in agricultural soils raises global concern, yet a systematic understanding of their national-scale distribution and drivers remains elusive. Here, we present the first comprehensive, nationwide analysis of MPs in Chinese farmland soils, integrating abundance, morphology, and polymer data from 169 sites across 31 provinces with regional agricultural practices and soil properties. The results showed that the abundance of MPs in Chinese farmland soils ranged from 240 to 12,720 items kg(-1). Among the identified MPs, films were the predominant morphological category, accounting for 58.4%, while small-sized particles dominated across dimensional distributions, accounting for 65.5%. Polyethylene (PE) was consistently the most prevalent polymer in all soil samples analyzed, accounting for 36.5%. The analysis results further clarified the key driving factors of MP distribution. The accumulation of MPs in soil environments resulting from local agricultural and human activities, or atmospheric deposition, may affect the transport and accumulation of small-sized MPs. Soil properties also affected the distribution characteristics of MPs. The abundance of MPs and pH were significantly and negatively correlated (p < 0.01). Soil electrical conductivity (EC) had a significant positive correlation with the abundance of fiber MPs (p < 0.05), and coarse sand content was positively correlated with pellet MP counts (p < 0.05). This study establishes that MP pollution in Chinese farmland is a spatially structured mosaic, governed by both human input and soil-specific retention. Our findings provide an empirical basis for targeted source control (e.g., plastic mulching film management) and advance risk assessment by incorporating soil-mediated fate processes.

While microplastics (MPs) have been extensively studied for their effects on soil nutrient cycling, their influence on ecosystem multifunctionality (EMF) across the entire crop growth cycle remains poorly understood. This study systematically investigated the impacts of a model biodegradable MP, polylactic acid (PLA), on soil microbiomes and EMF across different maize incubation periods. Results of 16S rRNA amplicon sequencing and metagenomic analysis revealed that PLA-MPs decreased bacterial community α-diversity, co-occurrence network complexity, and stability throughout the 120-day incubation period. Particularly, PLA-MPs exerted more pronounced effects at early incubation stages (30 and 60 days), and these effects were intensified with increasing PLA-MP concentrations. PLA-MPs suppressed anaerobic carbon fixation (porA, porB, frda) and pyruvate metabolism (ppdk), while promoting fermentation (L-lactate dehydrogenase), nitrogen fixation (nifD, nifH, nifK, anfG), and microbial phosphorus (P) acquisition (phoD, phn cluster). Over the entire incubation period, PLA-MP-induced shifts in nutrient cycling enhanced soil carbon (C) function by 37.6-569%, while decreasing nitrogen (N) and P functions by 8.40-22.4% and 16.8-56.2%, respectively. Path analysis revealed that PLA-MPs altered soil properties and bacterial community diversity, which in turn regulated functional genes and these individual soil functions, thereby reducing EMF by 2.05-27.0% (R2 = 0.923), with bacterial community diversity as the primary driver of EMF (standardized path coefficient of 0.978). These findings underscore the impacts of PLA-MPs on EMF in the soil-crop system throughout the entire maize growth cycle, advancing the understanding of the agroecological safety of biodegradable MPs.

Microplastics-derived dissolved organic matter (MPs-DOM), as a novel and non-negligible of DOM, significantly influences the photoaging of coexisting microplastics (MPs), but their interactions remain underexplored. In this study, we investigated the effects of different MPs-DOM (aromatic polystyrene DOM (PS-DOM), aliphatic polyethylene DOM (PE-DOM), and biodegradable poly(butylene adipate-co-terephthalate) DOM (PBAT-DOM)) on the aging behavior of PS-MPs and their transformations characteristics within 96 d of UVA irradiation. Result demonstrated that MPs-DOM notably accelerated the PS-MP aging (especially PBAT-DOM), and the aging rate was closely correlated with MP-DOM evolution. Notably, PS-MP exhibited significant and rapid increase in aging within the first 6h, which was attributed to the presence of highly unsaturated and phenolic compounds in MPs-DOM that promote the generation of reactive oxygen species (ROS). Throughout this process, these compounds were transformed into the saturated and low-aromatic compounds via the carboxylic acid and dealkylation reactions. As the reaction proceeded, PS-DOM released from PS-MP gradually became the dominant component in MP-DOM. The highly unsaturated components of PS-DOM have higher ability to produce ROS, thereby further accelerating PS-MPs aging. These findings provide valuable insights into the interactions between MPs and MPs-DOM and contribute to a better understanding of their environmental implications and risks.

Soil aggregate stability is vital for soil structure, erosion control, fertility, and crop productivity. Dissolved organic matter (DOM) turnover plays an important role in controlling the stability of soil aggregates, affecting aggregate formation and microbial activity. Microplastics (MPs) are known to impact soil DOM composition and structure, but their effects on DOM transformation in different soil aggregates remain unclear. Herein, we conducted 450 day incubation assays to study the effects of nondegradable and biodegradable MPs with varying aging levels on DOM transformations in agricultural soil aggregates. MPs were found to increase DOM transformation in soil aggregates, leading to changes in soil aggregate stability, including a reduction in geometric mean diameter and mass-weighted diameter. The addition of MPs resulted in a decrease in the stability of DOM in large-sized aggregates but an increase in the aromaticity and unsaturation of DOM in small-sized aggregates, which were more pronounced in the PLAMPs-treated group. This phenomenon is primarily attributed to the transformation of unsaturated aliphatic compounds and highly unsaturated and phenolic compounds, which play a major role in the intra- and intergroup transformation of DOM. In this process, microbial communities play a significant role. They tend to consume DOM in larger aggregates and produce DOM in smaller aggregates, leading to an accumulation of DOM in smaller aggregates, thereby promoting the formation of smaller aggregates and reducing the aggregate stability. This study uncovers the mechanisms of DOM transformation in response to MPs in soil aggregates, providing a scientific basis for soil management and sustainable agricultural development.

The pervasive prevalence of nanoplastics in environment poses a challenge that threatens ecosystem and agricultural production. Despite their ubiquity, the determinants of nanoplastics phytotoxicity and the mechanisms through which plants defend against this phytotoxicity remain poorly understand. In this study, it is demonstrated that the phytotoxicity of nanoplastics is inversely correlated with particle size. Specifically, polystyrene-nanoplastics sized at 20 nm dramatically inhibit root growth in Arabidopsis, while larger particles (100 to 1000 nm) have minimal effects. Mechanistically, these small nanoplastics primarily target the root meristem (RM), disrupting cell integrity and inhibiting cell division, which impairs root development. Plants employ two key defense strategies to counteract this toxicity: i) upregulating genes associated with RM maintenance and ii) accumulating auxin in the roots by inhibiting the auxin efflux transporter PIN2-dependent efflux of auxin, thereby reducing upward transport. However, this defensive response comes at a cost, as it also impairs root gravitropism, a critical process for plant adaptation to environmental changes. These findings provide valuable insights into the mechanisms of nanoplastic-induced phytotoxicity and plant defense, establishing a foundation for the development of biosafe plastic products and strategies to genetically enhance plant resistance to tiny nanoparticle exposure by optimization of intrinsic detoxification pathways.

Dissolved organic matter (DOM) is critical to soil ecosystems, with its dynamics influenced by exogenous substances like microplastics (MPs)-derived dissolved organic matter (MPs-DOM) from agricultural mulches. However, the impacts of MPs-DOM, especially at environmentally relevant concentrations, on soil DOM dynamics remain unclear. Here, we examined DOM transformation in yellow (YS) and black (BS) soils upon the addition of MPs-DOM, leached from biodegradable and nonbiodegradable mulches under ultraviolet irradiation (UV-MPs-DOM) and dark conditions (D-MPs-DOM), at environmentally relevant concentrations (3 mg C/kg). Results showed that extraction conditions, rather than mulch type, predominantly affected the bioavailability of MPs-DOM. UV-MPs-DOM, enriched in lipid-like and protein/amino sugar-like compounds, promoted soil DOM transformation. In YS, characterized by lower microbial diversity, UV-MPs-DOM enhanced DOM lability more than D-MPs-DOM. Conversely, in BS, with a diverse microbial community, UV-MPs-DOM with high bioavailability not only directly altered soil DOM composition but also was rapidly metabolized by the soil microbiome, particularly Proteobacteria, thereby resulting in increased soil DOM recalcitrance. However, the low bioavailability of D-MPs-DOM primarily exerted direct effects, contributing to its accumulation and increase in soil DOM lability. These findings provide novel evidence that MPs-DOM at environmentally relevant concentrations can alter soil DOM through distinct pathways, highlighting its potential long-term ecological risks.

This study investigated the solution conformation, microstructure, and rheological properties of a quaternary ammonium salt of sodium carboxymethyl cellulose (NaCMC) in aqueous solution. The results showed that the chain conformation of NaCMC exists in the form of linear aggregation of semi-flexible coils. NaCMC aqueous solution is a typical non-Newtonian fluid and can show shear-thinning behavior. Its viscosity increases with the increase of concentration (1.0%-3.0%, w/v) but decreases with the increase of temperature (5 degrees C-50 degrees C). The flow curve conformed with the Cross model fitting. The thixotropy index exhibited strong thixotropic behavior with the increase of concentration; the viscoelastic properties showed oscillatory behaviors between a dilute solution and an elastic gel, which exhibited random coil conformation with the potential to form a weak gel-like network. In addition, the viscosity at high concentrations (2.0%, 2.5%, 3.0%, w/v) and low temperatures (5 degrees C, 15 degrees C, 25 degrees C) almost conformed to the Cox-Merz rule, and NaCMC rheological properties are highly dependent on changes in concentration and temperature. Investigating the effects of concentration and temperature on the rheological properties of NaCMC can help us better understand its molecular behavior, providing theoretical support and optimization strategies for applications in drug delivery, food processing and packaging, cosmetics, and other fields.

Curdlan (CD), as a typical β-glucan, is becoming popular as a candidate for intelligent functional materials in the food industry and biomedicine. However, the water insolubility of CD limits its widespread application. Carboxymethylated derivatives of CD with different degrees of substitution (DSs) were fabricated. The structures were accurately characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), nuclear magnetic resonance (NMR), atomic force microscopy (AFM), and solution conformation analysis to explore the rheological properties and printability of carboxymethylated curdlan (CMCD). The cytotoxicity in vitro and biocompatibility in vivo for 3D printing scaffolds were systematically evaluated. This indicated that carboxymethylation significantly altered the crystal structure of CD, the CMCD with the DS greater than 0.49 showed calcium ion crosslinking properties and was in a state suitable for printing, making its rheological behavior more appropriate for specific applications, which may serve as a rapid prototyping of material for hydrogels in 3D printing bioinks. The printability of CMCD was not only related to the DS but also depended on its concentration. CMCD scaffolds exhibited excellent biocompatibility and low immunogenicity. These results provide new insights and approaches for the application of CD-based biomaterials in tissue engineering and related disciplines.

The therapeutic potential of essential oils in feed and medicine is limited by their volatility, degradation, and poor bioavailability. To overcome these challenges, a novel colon-targeted microsphere was engineered for the controlled delivery of tea tree essential oil (TEO), as illustrated in Scheme 1. A critical component of this system is a pH-responsive coating composed of pectin and starch, which acts as a colon-specific polymeric barrier. This coating demonstrated precise pH-responsive release, with minimal leakage in simulated gastric fluid (SGF) (only 10.87 % release over 4 h) and sustained, colon-specific release in simulated intestinal fluid (SIF) (79.77 % over 14 h). The core of the system, designated TEOCMT, was fabricated through the modification of montmorillonite (MMT) with cetyltrimethylammonium bromide (CTAB), resulting in organo-montmorillonite (CMT). Tea tree essential oil was then encapsulated within the interlayer spaces of CMT, forming an effective sustained-release system (TEOCMT). Compared to raw MMT (5.63 %), the TEO loading capacity of CMT increased 8.3-fold, reaching 46.79 %. Furthermore, the antibacterial activity of PS/TEOCMT microspheres was triggered in alkaline media, where they dissolved and released the TEOCMT core. This resulted in enhanced efficacy, particularly against S. aureus (MIC = 1.25 mg mL-1), which was superior to that of pure TEO (MIC = 2.5 mg mL-1). The PS/TEOCMT microspheres also exhibited excellent biocompatibility. This work presents a robust and effective strategy for unlocking the full potential of essential oils in colon-specific applications.

Microplastic-derived dissolved organic matter (MP-DOM) is emerging as a component of environmental dissolved organic matter (DOM), yet the molecular-scale interactions governing its behavior with iron minerals and their implications for photochemical reactivity remain poorly understood. This study investigates the molecular-scale interactions of five representative DOM types with goethite, focusing on reactive oxygen species (ROS) generation under simulated sunlight (UVA, 5.7 mW/cm2). Among the ROS species, hydrogen peroxide (H2O2) exhibited the most pronounced variation in yield across the different DOM types. DOM analysis revealed that natural DOM (humic acid [HA] and fulvic acid [FA]) contains hydroxyl/phenolic groups and sulfur-nitrogen heteroatoms, whereas MP-DOM (polystyrene [PS-DOM], polybutylene adipate terephthalate [PBAT-DOM], and polyethylene [PE-DOM]) is rich in aromatic and aliphatic structures. PS-DOM and PBAT-DOM induced significant lattice distortion and Fe(III) reduction, promoting oxygen vacancy formation, while PE-DOM exhibited minimal reactivity due to its hydrophobic structure. Optical and electrochemical characterizations showed that DOM lowered the conduction band position and narrowed the band gap of goethite, enhancing light absorption and charge separation. PS-DOM and HA induced the highest photocurrents and H2O2 yields, with PS-DOM enhancing H2O2 production via oxygen vacancy formation. Multivariate analysis identified condensed aromatics and sulfur-nitrogen groups as key regulators of ROS generation by promoting electron transfer and defect formation. This work demonstrates that DOM molecular features directly modulate the photoreactivity of goethite by controlling the efficiency of charge separation, defect density, and ultimately the yield of H2O2.

Cobalt, a high-grade metallic substance, is utilized across a wide variety of applications, ranging from joint prostheses to dental fillings. This has increased the level of human exposure to cobalt nanoparticles (CoNPs), potentially causing adverse local tissue reactions and implantation failure. The mechanisms are not fully understood. In this study, a macrophage model of cell exposure to CoNPs was employed to investigate the potential effects of CoNPs on cellular metabolic pathways and gene regulatory networks based on previous explorations on the complications of artificial joint implants. Results showed that CoNPs significantly affected cell membrane components and the expression of genes encoding extracellular matrix proteins. In addition, CoNPs downregulated amino acid metabolism and inhibited pentose metabolism. Based on the observed metabolome and transcriptome alterations, we concluded that the regulatory networks involving pentose and drug metabolism pathways may mediate CoNP-induced toxicity in macrophages. Therefore, beyond inflammatory responses, the combinatorial effects of numerous metabolic regulatory networks may also contribute to CoNP-induced cell damage, particularly in macrophages. These findings provide a deeper insight into the health concerns related to metal nanoparticles of implant materials and emphasize the necessity for safer applications of metal-containing implantable products.

Microplastics (MPs)-derived dissolved organic matter (MPs-DOM) is emerging as a significant contributor to environmental DOM pools. However, the molecular-scale processes governing its interactions with mineral and their effects on photoreactivity remain poorly understood. This study elucidates the structure-dependent molecular transformations and photochemical reactivity of DOM during its interaction with goethite, revealing distinct mechanisms driving reactive oxygen species (ROS) dynamics. Hydroxyl radical (•OH) production universally declined as goethite adsorbed electron-donating groups. Singlet oxygen (1O2) remained stable due to the presence of persistent aromatic photosensitizers. Triplet-excited DOM (3DOM*) exhibited divergent trends: humic acid (HA) and polybutylene adipate terephthalate (PBAT)-DOM showed decreases due to aromatic core adsorption, while fulvic acid (FA) and polystyrene (PS)-DOM exhibited increases driven by humification-stabilized quinoid systems and sulfonation-enhanced conjugation, respectively. The aliphatic inertia of polyethylene (PE)-DOM minimized ROS fluctuations. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) indicated that HA retained lignin-like components and stable sulfur/nitrogen heterocycles, while FA preserved branched quinones. PS-DOM underwent sulfonation, generating benzene sulfonates that enhanced 1O2 formation, whereas PBAT-DOM hydrolyzed to nitrogenous metabolites that suppressed •OH production. PE-DOM remained structurally resistant, consistent with its hydrophobic aliphatic chains. These findings emphasize that goethite's selective adsorption enriches redox-active aromatics in natural DOM but promotes the persistence of MPs-DOM through sulfurization and nitrogenization.

Ferrihydrite (Fh), as a ubiquitous iron (oxyhydr)oxide, plays an essential role in nutrient cycling and pollutant transformation due to its high surface area and diversified reaction sites. In the natural environment, Fh transformation could be easily influenced by coexisting components (particularly dissolved organic matter (DOM) and anions). As a new and important carbon source, microplastic-derived DOM (MP-DOM) directly or indirectly affects the morphology and fate of Fh, but limited knowledge exists about the combined effect of MP-DOM and anions on Fh transformation. Herein, this study elucidates the joint effects of polystyrene DOM (PS-DOM) and anions (such as Cl-, SO42-, and PO43-) on Fh transformation. Single anions (especially PO43-) were shown to inhibit the transformation of Fh to hematite (Hm) by hindering the dissolution and recrystallization of Fe(III). However, the inhibitory effect was strongly enhanced when PS-DOM and anions coexisted, which is attributed to their synergetic effects on inhibiting dissolution/recrystallization by occupying more active sites and hindering electron transfer. Furthermore, Fh transformation was predominantly controlled by PS-DOM, especially those containing high-unsaturation, high-oxidation-state, and O-rich phenolic compounds. These findings provide a new perspective on the significance of considering the joint effects of DOM and anions in evaluating the transformation of iron minerals.