Environmental Science: Nano最新文献

Nanoplastics (NPs) are emerging pollutants that widely exist in wastewater treatment systems, but their potential effects and mechanism of action on aerobic denitrifying bacteria remain unclear. This study investigated the effects of different concentrations (1, 10, 20, 50, 100 mg L⁻¹) of polystyrene nanoplastics with/without amino group (PS NPs and PS-NH₂ NPs) on a typical aerobic denitrifier, Pseudomonas stutzeri (P. stutzeri). The results indicated that NPs were abundantly adsorbed on the surface of P. stutzeri, which have hindered oxygen transfer and favored denitrification. The expression of genes related to nitrogen metabolism were both downregulated under the stress of NPs. However, PS NPs promoted the nitrogen removal performance by enhancing energy metabolism and biosynthesis, notably through the upregulation of the tricarboxylic acid (TCA) cycle and ribosome pathways. In contrast, PS-NH₂ NPs impaired the sdhC involved in the TCA cycle, leading to an obstruction of cellular energy metabolism. Additionally, PS-NH₂ NPs triggered more severe membrane damage and oxidative stress, leading to a significant upregulation of genes related to EPS secretion, biofilm formation, and ROS scavenging to alleviate cellular stress. However, this did not overcome the negative effects caused by the downregulation of nitrogen metabolism, energy metabolism, and biosynthesis, resulting in a decline in the nitrogen removal performance of P. stutzeri. This study provides an understanding of the potential mechanisms underlying changes in P. stutzeri to different NPs stressors.

Polymer nanocarriers (PNCs) are designed to deliver active ingredients in pharmaceuticals, food science and agricultural applications and it is essential to ensure their safety towards environmental and human health. Most research and guidance documents on the fate and effect of nanoparticles primarily focus on metal and metal oxide nanomaterials, while nanosafety research on organic nanomaterials is still in the early stages. This review aims to address a set of critical questions that currently prevent the risk assessment of PNCs. Our focus is on the analytical challenges associated with the detection, quantification and characterisation of PNCs in environmental and biological matrices. By addressing the key questions related to the durability, degradability and biological barrier-crossing properties of PNCs, we critically assess the analytical techniques used across different sectors. Our goal is to highlight the strengths and limitations of these analytical methods for the risk assessment of PNCs and to emphasize the significant overlap in the applications of PNCs across various sectors. We also discuss the urgent need for further research to scientifically advance analytical strategies for PNCs, which are essential for supporting responsible innovation in nanotechnology, ensuring the safety of both human and environmental health.

The intensive use of antibiotics and the inadequate removal in water treatment plants have contributed to the phenomena of antimicrobial resistance. Bacterial colonies and biofilms present in water distribution and aquatic systems respond to the presence of antibiotics by the generation of resistance genes and other determinants transmitted through the environment. In this perspective, we identify the opportunities and challenges of self-propelled micromotors in the fight against antimicrobial resistance by the elimination of antibiotics and bacteria in water. Recent progress is contextualized in the current scenario in terms of bacteria and antibiotics found in real settings and current removal technologies. As illustrated in this perspective, the unique features of micromotors result in a high surface area to-mass ratio for enhanced degradation capabilities, for both antibiotic removal and bacteria biofilm inactivation, as compared with static current technologies. The autonomous movement of micromotors allows us to reach more volumes of water and even hard-to-access areas, offering great opportunities to reach hard-to-access pipelines, not accessible by current approaches. Yet, as envisioned in this perspective, micromotors are far away from real applications, hampered mainly by the main challenges of the treatment of high-water volumes. We also advocate scientists to include in the proof-of-concept studies real water and the evaluation of a major number of antibiotics and bacteria commonly found in real settings, as will be described in this perspective. Micromotors hold considerable promise as a holistic approach to fight antimicrobial resistance, but cross-discipline collaborations are a must to translate the recent progress into real practical applications.

This study assessed the individual and binary toxic effects of inorganic mercury (Hg) plus total dissolved Ag (Ag), or silver nanoparticles (Ag NPs), on the immobilization, fatty acid composition, and oxidative stress of Artemia salina nauplii as an aquatic animal model. Acute toxicity tests revealed that the immobilization of nauplii exposed to 5 × 10⁻⁹ M, 2.5 × 10⁻⁸ M, and 5 × 10⁻⁸ M of Hg as HgCl₂ decreased in the presence of 1 × 10⁻⁴ M of Ag NPs or dissolved Ag as AgNO₃. The median effective concentration (EC₅₀) of Hg increased from 4.5 × 10⁻⁸ M to 9 × 10⁻⁸ M (two-fold) in the presence of Ag (Hg + Ag). Both Ag NPs and Ag decreased the immobilization of nauplii and diminished the oxidative stress and lipid peroxidation induced by Hg. Total amounts of saturated fatty acids (∑SFA) in Hg and Hg + Ag increased compared with that in the control, but this increase was significantly (P < 0.05) lower in Hg + Ag than in Hg. Total amounts of monounsaturated (∑MUFA) and polyunsaturated (∑PUFA) and the ratio of unsaturated to saturated fatty acids (unsat./sat.) decreased compared with the control; however, this reduction was significantly (P < 0.05) smaller for ∑PUFA in Hg + Ag than in Hg. In Hg + Ag NP co-exposure, ∑SFA and the unsat./sat. ratio showed no significant (P < 0.05) change compared with the control. However, MUFAs exhibited a significantly (P < 0.05) increased response, while the amount of PUFAs decreased compared with that in the control, but it was significantly (P < 0.05) higher than that in Hg. A decline in superoxide dismutase (SOD) and catalase (CAT) activity in nauplii due to exposure to mercury alone was mitigated in the presence of Ag or Ag NPs. The thiobarbituric acid reactive substance also decreased in the Hg + Ag and Hg + Ag NP treatments. The toxicity effect of the treatments was in the order of Hg > Hg + Ag > Hg + Ag NPs, revealing the antagonistic effect of Ag or Ag NPs on Hg toxicity, with the highest amelioration observed in the presence of Ag NPs.

The stabilization remediation performance of Cr(VI)-contaminated soil hinges on the remediation behaviors at soil–Cr(VI)–stabilizer multiple interfaces. Fe/C nanostructured materials featuring high chemical affinity, quick electron transfer and tunable active sites might tackle the problems of substance transport and structure evolution across multiple interfaces. Herein, we report that the co-pyrolysis of red mud and straw, two abundant solid wastes, can realize the scaled-up synthesis of biochar-supported nanoscale zero-valent iron (nZVI/BC). At an initial Cr(VI) concentration of 1000.00 mg kg⁻¹ and stabilizer dosage of 10%, the optimal nZVI/BC converted the Cr(VI)-contaminated soil into non-hazardous waste, with toxicity characteristic leaching procedure (TCLP) leaching concentrations of 3.13 mg L⁻¹ Cr(VI) and 11.26 mg L⁻¹ Cr(T). Experimental and theoretical results revealed that nZVI/BC altered the species evolution at the multiple interfaces of nZVI/BC–Cr(VI)–soil, where the acid-soluble Cr in soil shifted into stable residual Cr owing to the microscopically increased bidentate-binuclear inner-sphere coordination modes and the reduction process over the nZVI/BC surface. Meanwhile, the released iron species from nZVI/BC was immobilized on the soil surface, thereby regulating organic matter adsorption to recover soil agglomeration. Therefore, this study presents the feasibility of obtaining Fe/C nanostructured materials by one-step upgrading agricultural and industrial waste into eco-friendly stabilizers for remediating Cr(VI)-contaminated soils.

H₂O₂ is an important green oxidant, and activation of H₂O₂ is the key process determining its efficiency in removing environmental pollutants. However, due to complex catalytic sites and diverse active free radical products, the micro-mechanism of H₂O₂ activation and the selective regulation strategy are still ambiguous. Herein, single-atom catalysts (SACs) are selected as the model catalysts to investigate this fundamental mechanism. With a single active site, it is more beneficial to explain the mechanism. In this work, the differences in active free radical products (OH, ·OOH, ¹O₂) of H₂O₂ over three SACs (Fe, Co, Cu) and intrinsic selective regulation strategies are elucidated based on electron paramagnetic resonance (EPR) and density functional theory (DFT) calculation. EPR testing suggests that Co-SAC has the highest production of ·OH radicals, while Cu-SAC surpasses the other two catalysts in generating both ·OOH and ¹O₂ radicals. DFT calculations indicate that among the SACs, the lowest barrier of ·OH radical formation is Co-SAC (0.54 eV), while Cu-SAC demonstrates a notably lower energy barrier for ·OOH formation (0.26 eV) and ¹O₂ generation (0.51 eV), which is consistent with the EPR experimental results. More importantly, our work reveals that there is a linear relationship between charge transfer and the energy barrier of free radical generation. When the charge transfer amount is greater than 1.02, it is more inclined to promote the generation of ·OOH, and it will generate ¹O₂ free radicals when the charge transfer amount is smaller than 1.02. This work provides a predictive mechanism for SACs to selectively regulate the active free radical products, which is of great significance for developing green environmental protection technologies based on H₂O₂.