Environmental Science: Nano最新文献

Silver nanoparticles (nAg) raise ecotoxicological concerns due to their increasing production, application, and inevitable release into aquatic environments. In freshwater, nAg aggregate and partially dissolve, coexisting with dissolved silver (Ag⁺). Diatoms, key phytoplankton contributing to global silicon and carbon cycles, are particularly relevant for assessing silver toxicity, yet the metabolic impacts of Ag⁺ and nAg remain poorly understood. Here, we combined metabolomics and physiological assays to investigate the effects of short-term (2 h), sublethal exposures of Ag⁺ (0.01 and 0.02 mg L^-1) and nAg (0.1 and 0.3 mg L^-1) on the freshwater diatom Cyclotella meneghiniana. Both silver forms strongly affected the diatom metabolism, with notable alterations in amino acid, polyamine, glutathione, and nucleotide metabolism, as well as the tricarboxylic acid (TCA) cycle. These metabolic shifts were dependent on the silver form and concentration, and correlated with intracellular silver accumulation. Notably, nAg exerted stronger and more specific effects on the TCA cycle, glutathione metabolism, and polyamine synthesis than Ag⁺. Physiologically, both nAg and Ag⁺ impaired photosystem performance, but only nAg induced enhanced reactive oxygen species (ROS) production and altered carbonic anhydrase activity. This study provides the first insights into both shared and distinct metabolomic responses of diatoms to short-term exposure to Ag⁺ and nAg, highlighting the greater specificity and potency of nAg in disrupting key metabolic and physiological processes.

Cadmium (Cd) contamination severely restricts plant growth by impairing root development and physiological function. This study was laid out to investigate the potential of carbon quantum dots (CQDs) in alleviating cadmium-induced stress in dragonhead (Dracocephalum moldavica) roots. The effects of different cadmium levels (control, 25 and 50 mg CdSO₄ per kg of soil) and foliar treatments of water and CQDs (2, 4, 6, and 8 mg L⁻¹) on plants were investigated in a factorially arranged experiment. The CQDs markedly improved root performance under cadmium toxicity. Application of CQDs increased plant root length and dry mass by about 16% and 19% at 25 mg kg⁻¹, and 19% and 27% at 50 mg kg⁻¹ of cadmium toxicity, respectively, showing the protective roles of these materials. The CQDs also reduced Cd content in roots by approximately 12%, contributing to improved membrane integrity and reduced stress damage. These protective outcomes were associated with several physiological adjustments. Treatment with CQDs, particularly at 4 and 6 mg L⁻¹, noticeably increased activities of plasma and vacuolar H⁺-ATPases, root metabolic activity, and nutrient content (calcium, magnesium, potassium) in root tissues under cadmium toxicity. Furthermore, CQDs decreased the accumulation of stress-related molecules (abscisic acid, salicylic acid, phytochelatins, lignin, reactive oxygen species, lipid peroxidation, antioxidant enzyme activities, proline, and soluble carbohydrates), indicating lower oxidative and osmotic stress. These findings demonstrate the functional role of CQDs in alleviating cadmium toxicity by supporting root growth and modulating key physiological processes involved in ion transport, hormonal balance, and oxidative defense.

The convergence of nanoplastic pollution and cyanobacterial blooms presents a complex threat to aquatic ecosystems, yet the molecular mechanisms governing their interaction remain poorly understood. This is particularly critical for taste-and-odor compounds (T&Os) like geosmin (GSM) and 2-methylisoborneol (2-MIB), which compromise global water security. Here, we investigated the impact of positively charged amino-modified polystyrene nanoplastics (PS-NH₂) on the T&O-producing cyanobacterium Microcystis aeruginosa (M. aeruginosa). We found that low-concentration (1 μg mL⁻¹) exposure significantly inhibited T&O production, whereas high-concentration (20 μg mL⁻¹) exposure dramatically stimulated it, increasing total GSM and 2-MIB yields by 5.40- and 6.16-fold, respectively. An integrated transcriptomic and metabolomic analysis revealed that the high-dose effect is driven by a catastrophic cellular cascade. Severe oxidative stress and membrane damage cause a collapse of the photosynthetic apparatus, triggering a system-wide metabolic reprogramming that diverts carbon precursors overwhelmingly toward T&O biosynthesis. Conversely, the low-dose inhibition occurs without significant transcriptional changes, suggesting a rapid, adaptive resource allocation trade-off. These results reveal an unconventional toxicological pattern and provide a fundamental molecular blueprint for how nanoplastic stress can dysregulate cyanobacterial secondary metabolism, highlighting the critical need to consider non-linear responses in environmental risk assessment.

Environmental conditions significantly influence nanomaterial behaviour and physico-chemical transformations. Surface coatings initially enhance stability but degrade under environmental conditions, exposing nanomaterial cores and increasing transformation rates. These environmental transformations will impact nanomaterial bioavailability and ecotoxicity, with smaller particles and ionic species posing heightened toxicity to aquatic organisms, while larger agglomerates settle into sediments, posing risks to benthic ecosystems. The chronic environmental transformations of silver and titanium dioxide nanomaterials with different surface coatings over four years in diverse synthetic aquatic environments designed to mimic natural conditions are investigated. These conditions include a high-hardness salt only OECD-test medium (HH combo), and two synthetic waters representing low-alkalinity (class I) and high-alkalinity (class V) conditions, reflecting regional chemistries of areas such as Norway, the Alps, southern UK, and parts of southern Europe. A suite of analytical techniques, including dynamic light scattering, single particle inductively coupled plasma mass spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy, were employed to assess morphological and physicochemical transformations of the nanomaterials over time. This study underscores the importance of incorporating nanomaterial ageing and environmental transformation studies into regulatory frameworks to capture the dynamic lifecycle behaviours of nanomaterials and their evolving physico-chemical characteristics and consequent toxicity. Recommendations include mandating environmental testing under diverse conditions to simulate real-world scenarios, assessing coating stability, and adopting tiered risk assessment approaches. These findings provide crucial data for regulators to develop guidelines that reflect the dynamic nature of nanomaterials, enhancing our understanding of their long-term environmental persistence, mobility, and ecological impacts.

Petroleum oil contamination in marine and coastal environments poses significant ecological risks, necessitating the development of efficient remediation strategies. In this study, a modified nanobioremediation (m-NBR) platform is developed using green-synthesized silver(I) oxide (Ag₂O) nanocubes derived from Rhizophora apiculata (R. apiculata) leaf extract. The nanocubes are immobilized on rotatable polystyrene (PS) based floating biocarriers and integrated with Acinetobacter baumannii (A. baumannii). The Ag₂O nanocubes are characterized using spectroscopic and microscopic techniques to evaluate their structural and morphological properties. A. baumannii achieved 88.14% hydrocarbons (HCs) degradation within 10 days, which increased to 99.08% within 6 days upon incorporation of Ag₂O-functionalized floating biocarriers. The rotatable design enhances light exposure and pollutant contact, thereby facilitating photocatalytic activity and microbial attachment. These innovative synergistic effects of photocatalysis and biodegradation promote the breakdown of petroleum HCs into less toxic intermediates. These findings indicate that the present m-NBR platform is a highly promising approach for petroleum oil spill remediation in aquatic environments.

Doping of the surface of nanoscale zero-valent iron (nZVI) particles with noble metals enhances their reactivity and efficiency of pollutant removal. In this study, we explored the effects of different synthesis procedures on the performance of Cu-doped nZVI particles in the removal of trichloroethylene (TCE). The abundance, speciation, and distribution of Cu on the Cu–nZVI particle surface were analysed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX) mapping, and X-ray photoelectron spectroscopy (XPS). Based on the measurements of oxidation–reduction potential (ORP), pH, and dissolved Cu concentration, a 60 min reaction time was found to be optimal for the Cu–nZVI synthesis. The particles prepared with Cu(II) chloride and sulfate removed 67% more TCE than the non-modified nZVI particles in eight days, degrading it mainly to ethene. In contrast, particles synthesized with Cu(II) nitrate showed no increase the removal efficiency due to (i) higher pH of the dispersions, (ii) more passivated surface, and (iii) the presence of Cu in an amorphous form. Increasing the Cu loading above 1% did not improve the TCE removal rate likely due to the more extensive particle surface passivation. These findings provide insights into optimizing the synthesis and performance of metal-doped (n)ZVI particles for pollutant removal.