[en] Highlights: • Synthetic inhibitors mixed with urea and manure significantly lowed N₂O fluxes. • The reduction of N₂O emission closely linked with AOB community, but not AOA. • Soil AOB abundance were markedly inhibited by the nitrapyrin added treatments. • The changes in AOB community ascribed to edaphic factors of pH, NH₄⁺ and SOC. • Elevated temperature notably increased AOA, but decreased AOB abundance. Synthetic inhibitors and organic amendment have been proposed for mitigating greenhouse gas N₂O emissions. However, their combined effect on the N₂O emissions and ammonia-oxidizer (ammonia-oxidizing bacteria and archaea, AOB and AOA) communities remains unclear in calcareous soils under climate warming. We conducted two incubation experiments (25 and 35 °C) to examine how N₂O emissions and AOA and AOB communities responded to organic amendment (urea plus cattle manure, UCM), and in combination with urease (N-(n-butyl) thiophosphoric triamide, NBPT) and nitrification inhibitor (nitrapyrin). The treatments of UCM + nitrapyrin and UCM + nitrapyrin + NBPT significantly lowered total N₂O emissions by average 64.5 and 71.05% at 25 and 35 °C, respectively, compared with UCM treatment. AOB gene abundance and α-diversity (Chao1 and Shannon indices) were significantly increased by the application of urea and manure (P < 0.05). However, relative to UCM treatment, nitrapyrin addition treatments decreased AOB gene abundance and Chao 1 index by average 115.4 and 30.4% at 25 and 35 °C, respectively. PCA analysis showed that UCM or UCM plus nitrapyrin notably shifted AOB structure at both temperatures. However, fertilization had little effects on AOA community (P > 0.05). Potential nitrification rate (PNR) was greatly decreased by nitrapyrin addition, and PNR significantly positively correlated with AOB gene abundance (P = 0.0179 at 25 °C and P = 0.0029 at 35 °C) rather than AOA (P > 0.05). Structural equation model analysis showed that temperature directly increased AOA abundance but decrease AOB abundance, while fertilization indirectly influenced AOB community by altering soil NH₄⁺, pH and SOC. In conclusion, the combined application of organic amendment, NBPT and nitrapyrin significantly lowered N₂O emissions via reducing AOB community in calcareous soil even at high temperature. Our findings provide a solid theoretical basis in mitigating N₂O emissions from calcareous soil under climate warming.

[en] Highlights: • PM_2.5 caused severe cytotoxic effects on hESCs by elevating ROS level. • PM_2.5 induced down-regulation of Nrf2 signaling pathway in hESCs. • Akt and Erk pathways were not changed in PM_2.5-treated hESCs. • NAC could block cell apoptosis and rescue the activity of Nrf2 signaling pathway. -- Abstract: While the effects of fine particulate matter (PM_2.5) on embryonic toxicity are widely accepted, its exact mechanisms have not yet been fully elucidated, which partially attribute to lack of ideal research model. Embryonic stem cells (ESCs) have the capacity to differentiate into all cell types of three germ layers. Thus, they are ideal resources for the reproductive toxicity assessment in vitro. In the present study, we investigated the effects of PM_2.5 exposure on the oxidative stress and apoptosis of human ESCs (hESCs) and its possible mechanism. Our results showed that strong cytotoxicity high reactive oxygen species (ROS) level and fragmentation of nuclei were observed in the PM_2.5-treated hESCs. Meanwhile, up-regulation of apoptosis as well as down-regulation of Nrf2 signaling pathway were also observed after PM_2.5 treatment. However, we did not detect significant expression change or phosphorylation of Akt and Erk in PM_2.5-treated hESCs. Interestingly, scavenging of PM_2.5-induced ROS by N-acetylcysteine (NAC) could block cell apoptosis and rescue the activity of Nrf2 signaling pathway. In conclusion, we demonstrate that PM_2.5 is toxic to hESCs by inhibition of ROS-mediated Nrf2 pathway activity. Our findings suggest activation of Nrf2 pathway will help develop new strategies for the prevention and treatment of PM_2.5-associated disease.

[en] The development of new photocatalyst towards the highly efficient photo-reduction of U(VI) was highly desirable. In this study, ZIF-8/g-C₃N₄ photocatalyst was fabricated to photo-reduce U(VI) from aqueous solutions under different water chemistry. It is demonstrated that ZIF-8/g-C₃N₄ exhibited the fast-photocatalytic rate (completely photoreduction within 30 min), high photocatalytic activity (K_d > 10⁵ mL/g) and superior chemical stability (No significant decrease after fifth cycles). The photoreduction rate of U(VI) significantly decreased with increasing pH, H₂O₂ radicals and photo-generated electrons play an important role in U(VI) photoreduction by quenching experiments and ESR analysis. According to XPS and XANES analysis, adsorbed U(VI) was partly photo-reduced into U(IV) by ZIF-8/g-C₃N₄ photocatalyst. The highly efficient removal of U(VI) on ZIF-8/g-C₃N₄ photocatalyst was attributed to the synergistic effect of ZIF-8 and g-C₃N₄ photocatalyst. The present study may provide a new strategy to apply new photocatalyst for in-situ photoreduction of U(VI) in actual environmental remediation.

[en] Highlights: • The effective regeneration and magnetic properties of MFTP nanocomposite was constructed via simple preparation method. • The adsorption process of UO₂²⁺ ion towards MFTP nanocomposite, including surface adsorption and redox reaction. • The transition metal ion (Mn) and oxygen/nitrogen-containing groups enhanced the adsorption capacity of MFTP nanocomposite. Nanocomposite (MnFe₂O₄@TpPa-1, named as MFTP) adsorbent was developed by one-pot solvothermal method, using β-ketoenamine linked covalent organic frameworks (COFs, TpPa-1) as a supporting material to alleviate the aggregation of MnFe₂O₄. The properties were characterized by XRD, SEM, FT-IR, HRTEM, XPS, pH_pzc and others. The pseudo-second-order and Langmuir model were better description the adsorption process, and the maximum UO₂²⁺ ion adsorption capacity of MFTP (1235.01 mg/g) was much larger than that of MnFe₂O₄ (212.1 mg/g). The adsorption mechanism was complicated, including surface adsorption, oxidation, and reduction reaction. With the aid of XPS and the first-principle calculations, conformed that transition metal ion (≡Mn(II)) species and oxygen/nitrogen-containing groups participated in adsorption process. The experimental results shown that porous MFTP nanocomposite could be used as an effective and reusable adsorbent to remove/ recover UO₂²⁺ ion from wastewater or seawater.

[en] Mesoporous titanium dioxide with crystalline mesopore walls (M-TiO₂-ns) have been successfully synthesized through the self-assembly of poly 4-Vinylpyridine template and tetrabutyl titanate precursor based on their complex bond interaction under high temperature (180 °C) hydrothermal conditions. X-ray diffraction shows that M-TiO₂-ns have highly crystalline mesopore walls with anatase phase characters; N₂ sorption-desorption isotherms, SEM and TEM images show that M-TiO₂-ns have high BET surface areas (85 and 120 m²/g, respectively), large pore volumes (0.32 and 0.34 cm³/g, respectively) and crystalline mesopore walls, which exhibit monolithic morphology with crystal sizes around 3-5 μm. Interestingly, M-TiO₂-ns exhibit much higher catalytic activities and good recyclability in both induced reduction of decabromodiphenyl and oxidation of Rhodamine B under UV light than those of nonporous crystalline TiO₂ and M-TiO₂ templated by hydrocarbon surfactant of F127, which is even comparable with that of commercial P25. Combination of the unique characters such as crystallinity, stable mesostructure, large BET surface areas and superior photo catalytic activities make M-TiO₂-ns a kind of potentially important material for removing of organic pollutions in environment through green photo irradiation processes.

[en] Calcium peroxide (CP) has been widely applied in environmental remediation, but few studies have reported its application in controlling Microcystis blooms. To recognize its feasibility for mitigating Microcystis blooms, the properties of CP in terms of hydrogen peroxide (HP) release and phosphate removal were investigated at different CP doses, temperatures, and initial pH values. HP release kinetics followed the Higuchi model. Batch experiments conducted in this study suggested that the HP yield and release rate were positively correlated with the CP dose. Increasing temperature decreased the HP yield but accelerated the HP release rate. The phosphate removal kinetics were well simulated by the pseudo-second-order model. The batch experiments suggested that an increased CP dose enhanced the phosphate removal capacity, but it did not affect the phosphate removal rate. Moreover, increased temperature accelerated both phosphate removal capacity and rate. However, the initial pH of low-buffer-capacity solutions did not notably affect HP release and phosphate removal. According to laboratory experiments, HP released from CP could impair photosynthetic activity, resulting in Microcystis mortality. Furthermore, the reduced phosphate concentration in the solutions suggested that CP could facilitate the control of eutrophication, which directly reduced bloom formation. Hence, our results confirmed CP as a promising algicide for Microcystis bloom control, and it is worthwhile to develop novel methods for bloom mitigation based on CP.

[en] Highlights: • nZVI@SBA-15-PDA/PEI composites were developed via a facile method. • nZVI@SBA-15-PDA/PEI exhibited better performance of stability than nZVI. • Adsorption conditions played a vital role in the elimination of Cr(VI) and U(VI). • Removal of Cr(VI) and U(VI) was an adsorption and reduction process. Herein, a composite material (nZVI@SBA-15-PDA/PEI) was developed by loading nanoscale zero-valent iron (nZVI) on polydopamine-decorated SBA-15 for Cr(VI) and U(VI) removal. The structure, morphology and composition of the as-prepared composites were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffractometer (XRD) and fourier transform infrared spectroscopy (FT-IR) techniques. The experimental results demonstrated that the water environmental conditions played an important role in elimination of Cr(VI) and U(VI), such as pH values, pollutant concentrations and equilibrium time. Meanwhile, the fitted data displayed that the elimination process could be more accurately explained by the Langmuir and pseudo-second-order kinetic models, and the maximum removal capacities for Cr(VI) and U(VI) were 44.05 mg/g (pH = 3.0) and 57.78 mg/g (pH = 6.0) at 298 K, respectively. The characterization analysis conformed that the elimination mechanisms were proposed as a two-step interaction. Namely, both Cr(VI) and U(VI) were firstly attached onto the surface of composite materials via electrostatic interaction or surface complex reaction, and subsequently about 47.1% of U(VI) and 55.7% Cr(VI) were reduced to U(IV) and Cr(III) by nZVI. Thus, this nZVI composites exhibited a high potential to eliminate Cr(VI) and U(VI) from polluted water environment.

[en] Highlights: • The invasive plant (Solidago canadensis) was used to prepare biochar. • CaAl hydrotalcite or hydroxyapatite was used to decorate the biochar. • Both CaAl hydrotalcite or hydroxyapatite enhanced Eu(III) adsorption on biochar. • The adsorption mechanism involved complexation, ion exchange, and precipitation. In this paper, CaAl hydrotalcite or hydroxyapatite decorated invasive plant (Solidago canadensis)-derived biochar were synthesized by co-precipitation and high temperature pyrolysis method. The three composites and bare biochar were characterized by Scanning electron microscopy (SEM), X-ray spectroscopy (EDX), the Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS) techniques, and employed to remove Eu(III) from wastewater under a series of environmental conditions. The results indicated that the Eu(III) adsorption on BC@LDH@HAP was higher than that on BC, BC@LDH, and BC@HAP, and belonged to multi-layer adsorption, which was different from the monolayer adsorption of biochar. The adsorption could be fitted best by Langmuir model and the maximum adsorption capacity of Eu(III) on BC@LDH@HAP was up to 714 mg/g at pH ~ 6. The characterization results suggested that this excellent adsorption of BC@LDH@HAP arose from the abundant P-, C-, O-containing functional groups rather than larger specific surface area. The spectra of XPS, FT-IR, and XRD uncovered that the adsorption mechanisms of Eu(III) on BC@LDH@HAP involved surface complexation, ion exchange, and precipitation. Moreover, the absorbed Eu(III) was formed into two precipitate induced by P-containing groups and carbonate groups. This research confirmed BC@LDH@HAP is a promising material for the removal of Eu(III) in wastewater.

[en] Highlights: • An Al-based MOF, CAU-1 was prepared by solvothermal approach, and simple operation and cost-effective synthetic route. • The structure of CAU-1 possessed excellent thermostability, rich functional groups and large surface area. • The adsorption process of UO₂²⁺ ion, including chelation effect induced by nitrogen, oxygen-containing functional groups. • The adsorption mechanism of ReO₄⁻ ion onto CAU-1 could be electrostatic attraction and chelation effect. In this research, an Al-based metal-organic framework (MOFs), CAU-1 was prepared through complexation between 2-aminoterephthalic acid and Al (III) by solvothermal approach, and simple operation and cost-effective synthetic route. The objective was to immobilize the typical positive/negative radionuclide ions (UO₂²⁺/TcO₄⁻) in aqueous solution. The synthesized CAU-1 was characterized by XRD, FT-IR, TGA, FESEM, TEM-SAED, pH_pzc, XPS and N₂ physisorption analysis. The structure of CAU-1 possessed excellent thermostability, rich functional groups (‒NH₂ and ‒OH groups), as well as large surface area (1636.3 m²/g) and the micropore volume (0.51 m³/g). Furthermore, batch experiments demonstrated that CAU-1 with superior adsorption capacity was 648.37 (UO₂²⁺) mg/g and 692.33 (ReO₄⁻) mg/g calculating from Langmuir isotherm model, respectively. Thermodynamic investigation showed the adsorption process was endothermic and spontaneous. In addition, the adsorption mechanism of ReO₄⁻ ion onto CAU-1 could be electrostatic attraction and chelation effect, while for UO₂²⁺ ion, was mainly chelation effect induced by nitrogen-containing and oxygen-containing functional groups. Hence, the inexpensive and high-capacity CAU-1 could be considered as a practical material for sequestrations of radioactive pollutants from water environment.

[en] With the rapid development of computer and optical technique, as a powerful measuring method in hydrodynamics, flow visualization technique is able to get much flow field information in practical engineering. It also has an important meaning to projects and environmental areas. The image processing is the key to flow visualization for gaining flow field information. In terms of the PIV principles, the algorithm of PIV based on Fast Fourier Transformation (FFT) is studied, and the image mosaic program based on genetic algorithm has been compiled. The flow field of seabuckthorn flexible dam has been calculated and analyzed by using those methods as above-mentioned, and in the meanwhile, the application of flow visualization technique to measure the outdoor flow field has been studied exploringly, which proves that it is feasible to apply this technique to measure the large-scale outdoor flow field.