Recently, research on the biological effects of microplastics (MPs) has grown exponentially. However, effects of MPs on freshwater fishes and the mechanisms of the biological effects of MPs were limited. So, the purpose of the current study was to clarify the effects of microplastics on oxidative stress response, DNA fragmentation, and proteinogram of the early juvenile stage of Nile Tilapia (Oreochromis niloticus). The fishes were assigned into four groups: one control, three MPs-exposed groups as 1 mg/L of MPs, 10 mg/L of MPs, and 100 mg/L of MPs respectively for 15 days and 15 days of recovery. The activities of superoxide dismutase, catalase, total peroxides, and oxidative stress index (OSI), as well as lipid peroxidation and DNA fragmentation, increased in groups exposed to MPs compared to the control group in a dose-dependent manner. In contrast, the activity of total antioxidant capacity decreased in groups exposed to MPs compared to the control group in a dose-dependent manner. The electrophoretic pattern of muscle proteins revealed alteration in the proteinogram in the MPs-exposed groups compared to control. After the recovery period, the activities of superoxide dismutase, catalase, total peroxides, total antioxidant capacity, lipid peroxidation, DNA fragmentation, and the electrophoretic pattern of muscle proteins returned to normal levels in 1 mg/L of MPs-exposed group. Combined with our previous work, these results suggest that MPs cause the overproduction of reactive oxygen species (ROS) and alters the antioxidants parameters, resulting in oxidative stress and DNA damage. The present study fosters a better understanding of the toxic effects of MPs on Tilapia as a freshwater model. Graphical Abstract

Water quality environmental assessment often requires the joint simulation of several subsystems (e.g. wastewater treatment processes, urban drainage and receiving water bodies). The complexity of these integrated catchment models grows fast, leading to potentially over-parameterised and computationally expensive models. The receiving water body physical and biochemical parameters are often a dominant source of uncertainty when simulating dissolved oxygen depletion processes. Thus, the use of system observations to refine prior knowledge (from experts or literature) is usually required. Unfortunately, simulating real-world scale water quality processes results in a significant computational burden, for which the use of sampling intensive applications (e.g. parametric inference) is severely hampered. Data-driven emulation aims at creating an interpolation map between the parametric and output multidimensional spaces of a dynamic simulator, thus providing a fast approximation of the model response. In this study a large-scale integrated urban water quality model is used to simulate dissolved oxygen depletion processes in a sensitive river. A polynomial expansion emulator was proposed to approximate the link between four and eight river physical and biochemical river parameters and the dynamics of river flow and dissolved oxygen concentration during one year (at hourly frequency). The emulator scheme was used to perform a sensitivity analysis and a formal parametric inference using local system observations. The effect of different likelihood assumptions (e.g. heteroscedasticity, normality and autocorrelation) during the inference of dissolved oxygen processes is also discussed. This study shows how the use of data-driven emulators can facilitate the integration of formal uncertainty analysis schemes in the hydrological and water quality modelling community.

Surface water is one of the important landscape resources in tourist attractions. Due to tourism activities, the surface water quality (SWQ) in scenic was often damaged. An example of the Lushan Scenic, the SWQ, was analyzed and evaluated by water sampling and laboratory analysis methods. The results explained that the SWQ of Lushan Scenic was seriously damaged. The comprehensive index explained that the SWQ of seven sampling dots was from mild pollution to extreme pollution. The main pollutants were ammonia nitrogen, total nitrogen, and total phosphorus, and the TN and TP were the most serious. According to the data of tourists in 2017, the emergency water capacity stored by reservoirs was 32.5 days if there was no raining in Lushan Scenic. The main factors affecting the SWQ were tourism activities, such as tourists, hotels, restaurants, and other commercial activities, and pollutants discharged from domestic water were not completely treated in Lushan Scenic.

In this study, copper oxide nanorods were synthesized via surfactant-assisted chemical precipitation method and characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and UV-Visible spectrometer. XRD result reveals that CuO nanorods were structured in the monoclinic phase. SEM image suggested that synthesized CuO were shaped like nanorod with approximately 20–40 nm width and 500–800 nm length. The observed band gap calculated from UV-Visible absorption studies is 1.45 eV. As-prepared CuO nanorods were applied as a photocatalyst for the degradation of textile dye Reactive Black 5 (RB-5) in aqueous solution under the presence of visible light. The result exhibited that an enhanced degradation of RB-5 was achieved around 98% within 300 min and the experimental values were well matched with the linear fit model (R² = 0.97) and the observed rate constant found to be 5 × 10⁻³ min⁻¹. Therefore, as-synthesized CuO nanorods can be applied as a potential photocatalyst material for the degradation of organic pollutants in the wastewater.

Embracing energy efficiency (EE) and renewable energy (RE) is essential for improving environmental quality. This research investigates the asymmetric impacts of EE, RE, and other factors on CO₂ emissions in BRICS (i.e., Brazil, Russia, India, China, and South Africa) countries from 1990 to 2014. In contrast to previous studies, the present study considers EE as a major cause of CO₂ emissions in BRICS countries. By using the new hidden panel cointegration and nonlinear panel autoregressive distributive lag model, this study is the first of its kind that unfolds the asymmetric links among EE, RE, and CO₂ emissions. Findings clearly explain that the impact of the selected variables on CO₂ emissions is asymmetric, and both EE and RE help to lower CO₂ emissions in BRICS countries. In the long run, positive shocks in EE and RE can significantly mitigate CO₂ emissions in BRICS economies. In particular, a 1% fluctuation in the positive sum of EE reduces CO₂ emissions by 0.783% in the long run. On the other hand, a 1% fluctuation in the positive component of RE reduces CO₂ emissions by 0.733%. Moreover, individual country estimates suggest the heterogeneous effects among BRICS countries. Based on the empirical findings, policymakers should consider the asymmetric behavior of the EE, RE, and economic growth while formulating, energy, environment, and growth policies of BRICS countries. Graphical abstract

Simultaneous removal of NOx and SO₂ is carried out by an oxidation-absorption process, which NO oxidized by active hydroxyl radicals (·OH) derived from catalytic decomposition of vaporized H₂O₂ over Fe₃O₄/TiO₂ and then adsorbed by NaOH solution along with SO₂. Fe₃O₄/TiO₂ synthesized by wet impregnation method with an additional reduction under H₂ atmosphere was characterized by XRD, FTIR, BET, XPS, and VSM analysis. Effects of H₂O₂ concentration, H₂O₂ injection rate, reaction temperature, gas flow rate, and flue gas component on simultaneous removal were investigated. The experimental results show that NO can be effectively oxidized by highly reactive ·OH radicals generated from H₂O₂ decomposition over Fe₃O₄/TiO₂ catalyst, and removal efficiencies of 93.31% for NO, 85.90% for NOx, and 100% for SO₂ were obtained. The surface zero-valent iron (Fe⁰) and divalent iron (Fe²⁺) are the key factors of the catalytic oxidation with hydroxyl radical. H₂O₂ adsorption and dissociation mechanism on catalyst surface was studied using DFT calculation. The calculation results demonstrate that H₂O₂ prefers to dissociate on iron containing surface, and ·OH radicals generation follow by Haber-Weiss (H–W) mechanism. The stable oxidative product of HNO₂ and HNO₃ were generated through NO/NO₂ and H₂O₂ co-adsorption on the FeO/TiO₂ (0 0 1) surface.

Due to the wonderful property of hydrogels, they can provide a platform for a wide range of applications. Recently, there is a growing research interest in the development of potential hydrogel adsorbents in wastewater treatment due to their adsorption ability toward aqueous pollutants. It is important to prepare such a hydrogel that possesses appropriate robustness, adsorption capacity, and adsorption efficiency to meet the need of water treatment. In order to improve the property of hydrogels, much effort has been made by researchers to modify hydrogels, among which incorporating inorganic components into the polymeric networks is the most common method, which can reduce the product cost and simplify the preparation procedure. Not only can hydrogel be applied as adsorbent, but it also can be used as matrix for catalyst immobilization. In this review, the key advancement on the preparation and modification of hydrogels is discussed, with special emphasis on the introduction of inorganic materials into polymeric networks and consequential changes in the properties of mechanical strength, swelling, and adsorption. Besides, hydrogels used as adsorbents for removal of dyes and inorganic pollutants have been widely explored, but their use for adsorbing emerging contaminants from aqueous solution has not received much attention. Thus, this review is mainly focused on hydrogels’ application in removing emerging contaminants by adsorption. Furthermore, hydrogels can be also applied in immobilizing catalysts, such as enzyme and photocatalyst, to remove pollutants completely and avoid secondary pollution, so their progress as catalyst matrix is overviewed.

Fluoride (F), anion of fluorine which is naturally present in soil and water, behaves as toxic inorganic pollutant even at lower concentration and needs immediate attention. Its interaction with flora, fauna and other forms of life, such as microbes, adversely affect various physiochemical parameters by interfering with several metabolic pathways. Conventional methods of F remediation are time-consuming, laborious and cost intensive, which renders them uneconomical for sustainable agriculture. The solution lies in cracking down this environmental contaminant by adopting economic, eco-friendly, cost-effective and modern technologies. Biological processes, viz. bioremediation involving the use of bacteria, fungi, algae and higher plants that holds promising alternative to manage F pollution, recover contaminated soil and improve vegetation. The efficiency of indigenous natural agents may be enhanced, improved and selected over the hazardous chemicals in sustainable agriculture. This review article emphasizes on various biological approaches for the remediation of F-contaminated environment, and exploring their potential applications in environmental clean-up. It further focuses on thorough systemic study of modern biotechnological approaches such as gene editing and gene manipulation techniques for enhancing the plant-microbe interactions for F degradation, drawing attention towards latest progresses in the field of microbial assisted treatment of F-contaminated ecosystems. Future research and understanding of the molecular mechanisms of F bioremediation would add on to the possibilities of the application of more competent strains showing striking results under diverse ecological conditions.

Iron oxide-titanium oxide (Fe₂O₃-TiO₂) nanoparticles were developed as an effective adsorbent in order to extract and remove lanthanum ions selectively from aqueous media. Fe₂O₃-TiO₂ nanoparticles were prepared by simple hydrothermal method and structurally characterized using FESEM, EDS, XRD, FTIR, and BET techniques. The analytical potential of Fe₂O₃-TiO₂ nanoparticles was interpreted by applying the kinetic and isotherm models. The maximum static uptake capacity was 89.63 mgg⁻ ¹ at pH 7. Adsorption isotherm data evinced that a monolayer adsorption occurred on a homogeneous adsorbent surface which is compatible with Langmuir isotherm model. Data acquired from kinetic models study proved that La (III) adsorption onto Fe₂O₃-TiO₂ nanoparticles followed a pseudo-second-order kinetic equation. Thermodynamic study exhibited that a spontaneous process is favorable for adsorption mechanism of La (III) on Fe₂O₃-TiO₂ nanoparticles. Moreover, the existence of different coexisting ions did not influence the extraction of La (III). Finally, the recommended methodology was applied on several environmental samples.

To reveal the characteristics of tetracycline (TC) photocatalytic degradation under Cu(II) coexistence, effects of Cu(II) on TC photocatalytic degradation by ZnO nanoparticles (ZnO NPs) as a function of pH, humic acid (HA), and initial Cu(II) concentration were investigated. Interaction of TC with Cu(II) in the treatment process was analyzed by circular dichroism (CD) spectroscopy, while TC degradation pathway was investigated by high-performance liquid chromatography-mass spectrometry. Sixty-five percent and ninety-one percent TC degradation within 60 min in the absence and presence of Cu(II), respectively, was reported. Both adsorption and photocatalytic degradation of TC under Cu(II) coexistence increased with increasing pH from 3 to 6, while decreased with further increase in pH. HA inhibited the degradation of TC by ZnO NPs both in the presence as well absence of Cu(II), while TC degradation decreased from 91 to 73% and from 73 to 37% in the presence and absence of Cu(II), respectively. TC degradation by ZnO NPs first increased then decreased with increasing Cu(II). Maximum TC degradation (about 94%) was obtained in the optimum concentration range of Cu(II) (0.05–0.15 mmol/L). In addition, there was a lag effect between TC adsorption and degradation on ZnO NPs. TC degradation was improved via Cu(II)–TC surface complexation and followed N-demethylation and hydroxylation routes. This study could be of potential importance in extrapolating the transformation of TC or other antibiotics under the coexistence of heavy metals in water.