Nanoplastics (NPs) represent an emerging threat to aquatic ecosystems. However, their transgenerational transfer potential and associated toxicological consequences remain poorly characterized. In this study, the transgenerational transfer of polystyrene (PS) NPs was quantified and visualized in the floating macrophyte Spirodela polyrhiza using the metal-doped and bioimaging method. Beyond parental (F0) S. polyrhiza uptake via frond lower epidermis, PS accumulated through stipule-mediated mother-to-daughter frond transfer (MF-to-DF transfer) with an efficiency of 1-3%. Both F0 uptake and MF-to-DF transfer were insensitive to environmentally relevant PS weathering. The F1-to-F2 transfer efficiency exhibited a clear dose-dependent increase, rising from 0.2 to 0.6% at 0.1 mg L-1 to 0.7-1.1% at 5 mg L-1. Notably, a pronounced F2-specific phytotoxicity emerged, which was closely correlated with reduced growth (9 ± 4% lower specific growth rate) and frond number (12 ± 7% decline), whereas no comparable inhibition was observed in F1. Mechanistically, this phytotoxicity stemmed from transcriptional reprogramming (dysregulated circadian/photosynthesis-antenna pathways, activated stress resistance metabolites) at 5 mg L-1. These findings established that parental NP exposure could induce transgenerational growth inhibition in unexposed offspring; however, the extent to which these mechanistic observations apply to environmental scenarios (e.g., 0.1 mg L-1) remains to be determined. This represented a significant yet under-characterized ecotoxicological risk, and it critically escalated NP impacts from individual-level toxicity to population-relevant consequences in aquatic ecosystems.

ABSTRACT Mercury (Hg) methylators play key roles in the global Hg cycle. Nonetheless, the Hg methylators are widely present in Hg-absent environments and the Hg methylation is a cometabolic process without cell growth, which leave the origin and evolution of the Hg methylation as a mystery. Here, we reported the CCl 4 /trihalomethane-to-dihalomethane dehalogenation by model Hg methylators in a metabolic way. Heterologously-expressed HgcAB catalyzed both the CCl 4 dechlorination and Hg methylation. Halomethanes were shown to sustain the Hg-methylation community without adding external carbon source, electron donor and acceptor. Metadata analyses suggested the halomethane dehalogenation potential of Hg methylators at the global scale. These results, together with much higher global flux and kinetic V max of the metabolic halomethanes dehalogenation relative to the co-metabolic Hg methylation, suggested halomethanes as the potential HgcAB substrates for the evolution of Hg methylation.

Mounting evidence confirms that microplastics (MPs) pose ecological risks. Despite the environmental relevance of aged MPs under warming, little is known about their particle versus leachate toxicity. Here, we mechanistically quantify these contributions in the duckweed Spirodela polyrhiza at concentrations of 10-500 mg L-1. Our results reveal polymer- and end point-specific effects, indicating distinct modes of action. While particle effects dominated the toxicity of polyvinyl chloride (PVC, 55.2-86.2%) and polystyrene (PS, 50.5-67.1%), the toxicity of poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA) was primarily driven by their leachates (51.1-78.5% and 54.0-91.7%, respectively). High-risk chemical candidates, including docosanamide, pyrene, hexadecanamide, nonanoic acid, stearic acid, oxepanone, and adipic acid, were further identified and prioritized within the leachates from PLA and PBAT through nontarget screening via HPLC-MS and integration with the Toxicological Priority Index (ToxPi) framework. Although elevated temperatures enhanced chemical leaching, the resulting toxicity did not increase proportionally. By elucidating how particles and leachates differentially drive MP toxicity in a polymer-specific manner under warming, this work provides critical insights for developing mechanism-driven risk assessment frameworks.

Current understanding of mercury sulfide nanoparticles (HgS NPs) fails to adequately capture their long-term effects in soil-rice systems, particularly the dynamic interplay between NPs, rice plants, and soil microbes under field-relevant conditions. In this study, single-particle inductively coupled plasma mass spectrometry (spICP-MS) delineated a soil-to-grain mercury pathway mediated by HgS NPs at environmentally realistic concentrations (108-109 NPs g-1). Across the 111-day rice growth cycle, HgS NPs functioned as both vectors for plant uptake and key precursors for methylmercury (MeHg) formation, thereby defining grain mercury risk. Mercury-containing NPs detected in roots can be translocated to grains, with the filling stage as the critical window. Soil methylation displayed marked temporal dynamics (MeHg: 0.1-25.1 μg kg-1), governed by Hg bioavailability (glutathione-leachable mercury) and methylator abundance (hgcA gene copy number). Notably, exposure produced opposing yield outcomes: grain weight increased by 47 ± 20% at 108 NPs g-1 but decreased by 23 ± 12% at 109 NPs g-1, while total mercury accumulated to 27.1-147.9 ng g-1 in brown rice at both doses, underscoring concurrent threats to yield and food safety. This refined understanding advocates for an integrated mitigation approach: growth-stage management to block filling-phase translocation into grains, combined with targeted soil interventions to inhibit MeHg formation, thereby mitigating dietary mercury exposure from rice.

We examine the effects of polystyrene (PS) NPs at 5.4 ± 1.0 nm on rice (Oryza sativa L.) under two scenarios: a comparative 14-day hydroponic exposure (3.6-35.7 μg PS plant-1 d-1) of root vs foliar exposure and a 30-day soil-based foliar exposure (5.3-73.4 μg PS plant-1 d-1) from heading to maturity. PS NPs exhibit route-specific phytotoxicity: while only high-dose root exposure inhibits photosynthesis, foliar exposure causes sustained inhibition. Importantly, soil-based foliar exposure also inhibits photosynthesis without the PS NP translocation to grains. This foliar-specific inhibition correlates directly with PS accumulation in leaves and is mechanistically attributed to its colocalization with chloroplasts (Pearson's r = 0.592), as confirmed by confocal imaging in high-dose (35.7 μg PS plant-1 d-1) exposed leaf. The colocalization impairs both the light-dependent reactions and carbon fixation during photosynthesis, as evidenced by significant reductions in photosynthetic pigments (54.4-61.0%), Hill reaction activity (49.9-70.2%), ATP production (22.1-24.3%), net photosynthetic rate (84.5-89.0%), Rubisco activity (84.6-87.5%), stomatal conductance (47.9-69.5%), and transpiration rate (47.4-48.9%). Transcriptomic analysis identifies the genetic basis of this inhibition, showing significant downregulation of the core photosynthesis pathway and key genes for photosynthetic-antenna proteins, carbon fixation, and carotenoid/porphyrin metabolism. These findings provide mechanistic insights into PS NP-induced photosynthesis inhibition and underscore atmospheric NPs as an emerging threat to global food security.

Mercury pollution, in conjunction with other contaminants, hampers progress toward the United Nations Sustainable Development Goals. The Minamata Convention on Mercury, which came into force in 2017, represents a critical step in combating this global issue. However, evaluating its effectiveness faces a major challenge, that is, establishing a clear link between reduced mercury emissions and lessened human exposure to neurotoxic methylmercury. Here, we propose that a previously overlooked methylmercury detoxification pathway in primary producers holds the potential to bridge the gaps in the emission-exposure nexus. A comprehensive understanding of this in vivo methylmercury demethylation and mercury reduction will enhance the effectiveness of global mercury mitigation efforts, accelerating our pace toward a sustainable future.

Micro(nano)plastics (MNPs) are widely detected and persistent in soil ecosystems, posing long-term risks to soil invertebrates. However, the long-term effects of MNPs across generations on soil invertebrates remain unclear. In this study, the effects of polystyrene nanoplastics (PS NPs) and microplastics (PS MPs) at 0.001 %-0.05 % on both parental and offspring earthworms were examined. Compared to control (CK), PS NPs at 0.01 % and 0.05 %, as well as PS MPs at 0.005 %-0.05 % resulted in a decrease in the number of offspring by 34.41 %-39.23 % and 23.60 %-32.15 %, respectively. This suggested a disturbance on the reproduction ability of parents, consistent with the observed seminal vesicle damage. In addition, PS MNPs decreased the growth of parents and offspring by 5.28 %-27.40 % and 28.15 %-43.47 % relative to CK, which could be associated with the observed intestinal damage and oxidative stress. Furthermore, offspring exhibited greater growth inhibition and oxidative stress than their parents, indicating the multigenerational effect of PS MNPs. Metabolomics analysis revealed that PS NPs and PS MPs exposure at 0.05 % inhibited the growth and reproduction of parents via disturbing the membrane transport (ABC transporters), protein translation (aminoacyl-tRNA biosynthesis), and nucleotide metabolism (purine metabolism). Moreover, PS concentration exerted significant effects on individual and biochemical indexes, while particle size induced greater disturbances on the metabolism of parents under the exposure conditions used in this study. Our results highlighted the importance of investigating the long-term effects to comprehensively and accurately assess the ecological risk of MNPs.

The methylation of mercury-containing nanoparticles (Hg-NPs) into neurotoxic methylmercury (MeHg) poses threats to wildlife and humans. However, how autochthonous dissolved organic matter (DOM) affects the occurrence and MeHg production of Hg-NPs remains poorly understood. In this study, the distribution of Hg-NPs and their interactions with autochthonous DOM in the Nanfei River, an urban river in eastern China, were systematically explored. Field investigations revealed that mass concentrations of Hg-NPs increased along the flow path, rising from 0.10 ± 0.06 to 0.91 ± 0.21 ng·L-1, and were positively correlated with MeHg levels (p < 0.001), indicating that Hg-NPs (predominantly < 60 nm in diameter) are bioavailable substrates for Hg methylation in the river. The spatial distribution of Hg-NPs was primarily driven by the increasing level and changing composition of DOM along the river, particularly by fractions with a higher degree of humification and higher molecular weight. Laboratory experiments showed that algae-derived DOM, which has a higher content of aromatic protein, was more effective in promoting Hg-NP formation and maintaining their net MeHg production than other DOM sources. These findings highlight the critical role of autochthonous DOM, particularly algae-derived DOM, in regulating the occurrence and methylation of Hg-NPs, providing new insights into MeHg risk prediction under algal blooms.

The occurrence of metal-containing nanoparticles (Fe-, Pb-, Ti-, Cu-, Mn-, Cr-, Hg-, and Ag-NPs) in leachates from 74 municipal solid waste (MSW) disposal sites, spanning 7500 latitudinal kilometers and serving an urban population of 39.6 million, was quantified by single-particle inductively coupled plasma mass spectrometry. All leachate samples contained more than three metal-containing NPs, with the summed number concentrations and sizes ranging from 109 to 1014 particles L-1 and from 12 to 100 nm, respectively. Transmission electron microscopy with energy-dispersive X-ray spectroscopy analysis of representative subsamples further revealed the colocalization of multiple elements within individual NPs, indicating heteroaggregation and/or complexation with metal ions. MSW leachates serve as long-term sources of metal-containing NPs to groundwater because the summed number concentrations of metal-containing NPs in the downgradient groundwater were 2.2-515.7 times higher than their counterparts in the upgradient groundwater. Random forest models further identified leachate total organic carbon (TOC) and total metal concentrations as the primary drivers of NP spatial heterogeneity, enabling global NP mapping and hotspots identification. Under effective TOC mitigation (≤30.3 mg L-1), 84% of leachates showed NP reductions of 6-99.4%. These findings provide a prioritized framework for NP monitoring and MSW sites management, supporting the Basel Convention's goals for sustainable waste management.

Nanoplastics (NPs) are chemically reactive following abiotic and biotic weathering processes. These weathered NPs have the potential to facilitate the transformation of legacy contaminants, such as heavy metals.

The role of microplastics (MPs) in transforming coexisting contaminants in aquatic environments is poorly understood. Herein, the mediation of polystyrene (PS) MPs on the phototransformation of silver ions (Ag+) was investigated. Ag-based nanoparticles (21.0-177.0 nm) formed from Ag+ in the presence of PS MPs (8.3-41.9 μm) after 40-day natural light and 96-h UV light irradiation, as detected by single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS). Using a successive dissolution method, the species were identified as Ag0, Ag2O, and Ag2S nanoparticles. After 96 h of UV irradiation, Ag0 was the main nanoparticle species (93.4%), accounting for 78.0% of the total Ag. Both the MPs surface and the liquid phase were confirmed as Ag0 nanoparticle formation sites, whereas Ag2O and Ag2S were mainly formed in the liquid phase. Free radicals (superoxide radicals, oxygen-centered persistent free radicals) and oxygen-containing groups (aldehyde groups) on the MPs surface and dissolved organic matter in the liquid phase played crucial roles in Ag0 nanoparticle formation. Furthermore, sulfur species (e.g., S2- and S2O32-) in the liquid phase were responsible for the Ag2S nanoparticle formation. These findings are crucial for better understanding the environmental fate, geochemical cycle, and risk of both MPs and Ag+.

Growing evidence has indicated that mercury sulfide nanoparticles (HgS NPs) are the potential precursors for neurotoxic methylmercury. But how and which soil components affect HgS NP retention remains unclear. Here, we examined the retention of uncoated and humic acid coated HgS NPs in 18 natural soils with varied properties. Our results suggested that the Kr values (retention coefficients) for uncoated and humic acid HgS NPs were 2.46 × 103 to 8.32 × 105 L kg− 1 and 3.00 × 103 to 2.73 × 105 L kg− 1, respectively. Soil properties (i.e., electrical conductivity, organic matter (OM), oxalate-extractable Fe and Mn) significantly affected the uncoated HgS NP retention, accounting for 69

Plastic debris has recently been identified as a hotspot for abiotic metal transformations, triggered primarily by photo-weathering under sunlight. Here we perform a set of experiments with freshwater in the field and laboratory to explore metal transformations under dark conditions. We demonstrate that light-independent weathering of plastics leads to methylation of inorganic mercury (Hg(II)) in waterbodies. We propose that methylation occurs via an abiotic pathway involving three chain reaction steps, namely the release of plastic-derived dissolved organic matter (P-DOM), complexation of P-DOM with Hg(II) and intramolecular transfer of methyl groups. P-DOM is released during the light-independent oxidation of plastics via reactive oxygen species. Density functional theory simulations confirm the thermodynamic feasibility of the intramolecular transfer of methyl groups to Hg(II), upon its complexation with oxygen-containing groups in P-DOM. Model estimates demonstrate that polypropylene in freshwater produces methylmercury via this abiotic pathway with Hg(II) methylation potentials from 2.8 × 10−5

Understanding how ecosystems respond to ubiquitous microplastic (MP) pollution is crucial for ensuring global food security. Here, we conduct a multiecosystem meta-analysis of 3,286 data points and reveal that MP exposure leads to a global reduction in photosynthesis of 7.05 to 12.12% in terrestrial plants, marine algae, and freshwater algae. These reductions align with those estimated by a constructed machine learning model using current MP pollution levels, showing that MP exposure reduces the chlorophyll content of photoautotrophs by 10.96 to 12.84%. Model estimates based on the identified MP-photosynthesis nexus indicate annual global losses of 4.11 to 13.52% (109.73 to 360.87 MT·y −1 ) for main crops and 0.31 to 7.24% (147.52 to 3415.11 MT C·y −1 ) for global aquatic net primary productivity induced by MPs. Under scenarios of efficient plastic mitigation, e.g., a ~13% global reduction in environmental MP levels, the MP-induced photosynthesis losses are estimated to decrease by ~30%, avoiding a global loss of 22.15 to 115.73 MT·y −1 in main crop production and 0.32 to 7.39 MT·y −1 in seafood production. These findings underscore the urgency of integrating plastic mitigation into global hunger and sustainability initiatives.

Interfacial interactions control the environmental risk of silver nanoparticles (AgNPs) by mediating their exposure and biological outcome relationships. Despite recognizing their importance, current risk paradigms fail to adequately capture the inherent complexity of these reactive interfaces - dynamic systems where multiscale transformations and biological interactions occur simultaneously. This often results in oversimplified models that poorly predict real-world behavior. Here, we synthesize recent advances in understanding AgNP interfacial behaviors, including abiotic transformations (i.e., partitioning, dissolution, sulfidation, and chlorination) and plant-nano interactions. We present an integrated framework that combines in situ characterization techniques, computational approaches that integrate thermodynamic datasets with computational chemistry models at environmental relevant low concentrations, and life-cycle-oriented mesocosm experiments, to quantitatively link interfacial processes with biological impacts. The resulting mechanistic insights advance predictive risk assessment in multi-scale environments and inform the development of safer nanotechnology applications in natural systems.

Mercury sulfide nanoparticles (HgS NPs) are ubiquitous in nature and are methylated to neurotoxic methylmercury (MeHg) by microorganisms. However, there is a paucity of knowledge regarding the biokinetics of HgS NPs in microorganisms. Here, the biokinetic uptake and efflux of HgS NPs in the model bacterium (Escherichia coli) were quantified and compared with those of Hg-dissolved organic matter complexes (Hg-DOM). The results demonstrate that the uptake of HgS NPs was time- and concentration-dependent. The uptake rate constant of HgS NPs was 0.031 ± 0.006 L g-1 h-1, which was 2.4-fold higher than that of Hg-DOM. Meanwhile, the internalized Hg in E. coli was depurated, as evidenced by the presence of Hg-containing NPs in the culture media. The efflux rate constant of HgS NPs and Hg-DOM were comparable (0.028 ± 0.007 h-1 vs. 0.031 ± 0.009 h-1). Consequently, HgS NPs exhibited a significantly higher bioconcentration factor (BCF; 1107 ± 63 L kg⁻1) than Hg-DOM (419 ± 57 L kg⁻1), suggesting their enhanced bioavailability and therefore greater methylation potential in Hg-methylating bacteria. These results demonstrate the unique characteristics of HgS NP uptake kinetics, which are essential for capturing their bioaccumulation mechanisms and providing more reliable and accurate risk assessments.

The current and continued influx of engineered nanoparticles (NPs) into the environment is significant, including the release of NPs that have been historically stored or retained in soils to various waterbodies. However, the reactivity and dynamic nature of NP transformation processes are poorly understood due to the lack of long-term environmentally relevant experiments that accurately represent ecosystem complexity. Here, we established a two-year mesocosm system to quantify the relative reactivity of silver sulfide NPs using stable isotope tracers, with more recent 109Ag2S-NPs inputs to the 80 L water column (water-borne NPs, 141 mg) and historically stored Ag2S-NPs in soils (soil-borne NPs, 4.5 +/- 0.3 mu g g-1). Soil-borne NPs accounted for 59.4-92.1% of the Ag accumulation in the grain of rice Oryza sativa L. (31.4-112.4 mu g kg-1), radish roots Raphanus sativus L. (106.2-396.7 mu g kg-1), and rice borers Chilo suppressalis (21.5-30.7 mu g kg-1), highlighting the significance of soil-borne NPs in agricultural ecosystems. Based on the measured soil-to-plant transfer factors, recommended concentrations of soil-borne NPs should be less than 2.4 mu g Ag g-1 for rice growth and 0.7 mu g Ag g-1 for radish growth to minimize human exposure to silver via consumption of these edible tissues. This work demonstrates that quantifying the reactivity of NP transformation processes and different NP fractions in the environment is not only important for accurately characterizing the risk of these materials but also for ensuring the safety and sustainability of agriculture.