Electro-assisted Adsorption of Zn(II) on Activated Carbon Cloth in Batch-Flow Mode: Experimental and Theoretical Investigations.

High levels of zinc ion (Zn2+) in environmental scenarios have long been considered to be harmful, and this study was experimentally and theoretically performed to explore the feasibility of electro-assisted adsorption of Zn2+ on activated carbon cloth from aqueous solutions in batch-flow mode. The characteristics of carbon cloth were systematically evaluated using cyclic voltammetry and various surface characterization techniques. Effects of operating parameters, including charging voltage, feed Zn2+ concentration, solution volume, and flow rate, on the dynamic removal process of Zn2+ were examined. Meanwhile, a theoretical model was developed to quantitatively describe the electro-assisted adsorption of Zn2+, and an excellent agreement between the modeling results and the experimental data was observed. The Zn2+ removal mechanisms involve both nonelectrostatic interactions (physi- or chemisorption) and electrostatic interactions. Experimental and theoretical results demonstrated a significant enhancement of Zn2+ adsorption capacity on the carbon electrodes under the electro-assistance. Moreover, the carbon electrodes exhibited good regeneration performance achieved via a simple short-circuiting method and provided good reproducibility over consecutive runs for the removal of Zn2+. The validated model could be applied to predict the effects of important parameters that are difficult to be experimentally manipulated, and is expected to play an important role in establishing the electro-assisted adsorption as a viable treatment technology for zinc wastewater.

Responses of seeds of typical Brassica crops to tetracycline stress: Sensitivity difference and source analysis.

Antibiotics can induce adverse effects on plants. Brassica crop seeds, for their advantages, are used widely in seed germination test to investigate phytotoxicity of substances. However, their performances on evaluating antibiotics remain to be studied to select sensitive species for control of potential risks. In this work, common species of Chinese cabbage (Brassica rapa L.), edible rape (Brassica napus L.), and cabbage (Brassica oleracea L.) with three cultivars each were selected to compare and analyze the sensitivity difference of their seeds to tetracycline (TC) stress. Results showed that the ratio of axis to cotyledon (RAC) by fresh weight was an alternative endpoint besides radicle length (RL) in the test. The species sensitivity distribution (SSD) based on the effective concentrations causing x% inhibition (ECx) in RL of seeds exposed to TC was applied to compare the sensitivity of seeds and estimate the hazardous concentration for x% species (HCx). From the species-dependent sensitivity and the sensitivity difference of cultivars in the same species of seeds to TC, the performance of Chinese cabbage was the best in the study. The sensitivity of seeds to TC could be evaluated by EC20 related to seed physical traits and germination indices, while the extent of seeds affected by TC could be evaluated by EC50 related to the composition of seed storage reserves. We recommended that it was a new idea to analyze responses of different seeds to TC at large scale according to seed innate characteristics.

Synergistic effect of intercalation and EDLC electrosorption of 2D/3D interconnected architectures to boost capacitive deionization for water desalination via MoSe2/mesoporous carbon hollow spheres.

Transition-metal dichalcogenides can be used for capacitive deionization (CDI) via pseudocapacitive ion intercalation/de-intercalation due to their unique two-dimensional (2D) laminar structure. MoS2 has been extensively studied in the hybrid capacitive deionization (HCDI), but the desalination performance of MoS2-based electrodes remains only 20-35 mg g-1 on average. Benefiting from the higher conductivity and larger layer spacing of MoSe2 than MoS2, it is expected that MoSe2 would exhibit a superior HCDI desalination performance. Herein, for the first time, we explored the use of MoSe2 in HCDI and synthesized a novel MoSe2/MCHS composite material by utilizing mesoporous carbon hollow spheres (MCHS) as the growth substrate to inhibit the aggregation and improve the conductivity of MoSe2. The as-obtained MoSe2/MCHS presented unique 2D/3D interconnected architectures, allowing for synergistic effects of intercalation pseudocapacitance and electrical double layer capacitance (EDLC). An excellent salt adsorption capacity of 45.25 mg g- 1 and a high salt removal rate of 7.75 mg g- 1 min-1 were achieved in 500 mg L- 1 NaCl feed solution at an applied voltage of 1.2 V in batch-mode tests. Moreover, the MoSe2/MCHS electrode exhibited outstanding cycling performance and low energy consumption, making it suitable for practical applications. This work demonstrates the promising application of selenides in CDI and provides new insights for ration design of high-performance composite electrode materials.

Effective fluoride removal from brackish groundwaters by flow-electrode capacitive deionization (FCDI) under a continuous-flow mode.

Herein, we demonstrated the suitability and effectiveness of utilizing flow-electrode capacitive deionization (FCDI) for treatment of fluoride-contaminated brackish groundwater. By comparing operational modes of short-circuited closed-cycle (SCC), isolated closed-cycle (ICC) and single cycle (SC), it was found that SCC mode was the most advantageous. In SCC configuration, the effects of different parameters on the removal of F- and Cl- were investigated including current density, hydraulic residence time (HRT), activated carbon (AC) loading and feed concentration of coexisting NaCl. Results indicated that the steady-state effluent Cl- concentration dropped with elevated applied current, and the decreasing rate got faster with the increase of HRT or AC loading. However, for the steady-state effluent F- concentration, it dropped to a value under a small applied current and maintained stable in spite of the increase in applied current, and both HRT and AC loading had insignificant effects on the steady-state effluent F- concentration. F- was preferentially removed from the treated water compared with Cl-, and a higher ion selectivity could be obtained at lower applied current and smaller HRT with the trade-off being that operation under these circumstances would generate outlet water with little change in conductivity compared to the influent. The removal efficiencies of F- and Cl- both decreased with increasing feed concentration of coexisting NaCl. This study should be of value in establishing FCDI as a viable technology for treatment of fluoride-contaminated brackish groundwater.

Microcystis aeruginosa's exposure to an antagonism of nanoplastics and MWCNTs: The disorders in cellular and metabolic processes.

Nanoplastics and carbon nanotubes (CNTs) is one of the emerging environmental contaminants and a widely used engineering nanomaterial, and their biological toxicity has been frequently studied. However, there has been no research on the combined exposure of these two totally different shape nanoparticles. To explore their potential threat to freshwater ecosystems, Microcystis aeruginosa (M. aeruginosa) was exposed to concentration gradients of polystyrene nanoplastics (Nano-PS) and multi-walled carbon nanotubes (MWCNTs). The physiological analysis and whole-transcriptome sequencing were integrated to certify the cytotoxicity. As the physiological results showed, the low concentration (5 mg/L) of these two nanoparticles showed a stimulation on the growth (6.49%-12.2%) and photosynthesis (0-7.6%), and the coexposure was slightly higher than individuals. However, other concentrations showed inhibitory effect, especially at high concentration (50 mg/L), and all physical signs and electron microscope images showed obvious cytotoxicity. Compared with the individuals, the coexposure showed an antagonistic effect induced by the heterogeneous agglomeration which decreased the surface toxicity and the contact with algae of nanomaterials. Transcriptome results showed that coexposure treatment had the fewest differential genes, and the primary effects embodied in the disturbances of cellular and metabolic processes which were superior to the individuals. In the 50 mg/L Nano-PS, the translation process was significantly disordered, and MWCNTs could disrupted the photosynthesis, multiple metabolism processes, membrane transport, and translation. These findings demonstrated the aquatic toxic mechanism from cellular and metabolic processes of Nano-PS and MWCNTs for M. aeruginosa and provided valuable data for environmental risk assessment of them.

Photocatalytic degradation of tetracycline antibiotics using delafossite silver ferrite-based Z-scheme photocatalyst: Pathways and mechanism insight.

Tetracycline (TC), a widely used antibiotic, is easy to enter the aquatic ecosystem through soil erosion, livestock manure and wastewater discharge, resulting in a series of risks. The application of Z-scheme photocatalysts with efficient interface charge separation and transfer has been regard as an effective strategy for antibiotic degradation. Herein, a novel ternary Z-scheme Bi12O17Cl2/Ag/AgFeO2 was successfully synthesized by ultrasound-assisted ethanol reduction of Ag+ on the interface of Bi12O17Cl2 and AgFeO2. The Bi12O17Cl2/Ag/AgFeO2 Z-scheme system exhibited an enhanced photocatalytic degradation capability for TC, which was over 6.5 times and 2.4 times higher than those of AgFeO2 and Bi12O17Cl2/AgFeO2 system, respectively. The photocatalytic process of TC was explored, and the results indicated that an optimum catalyst concentration of 0.5 g L-1 and a primeval pH (without adjustment) favored the degradation process, while the introduction of exogenous anions (CO32-, SO42- and NO3-) and organic matter (HA) supressed the degradation of TC. Simultaneously, the possible pathway for the degradation process of TC was presented based on the liquid chromatography-mass spectrometry (LC-MS) analysis. Active species trapping experiments and ESR spectra revealed the significant contribution of O2- in the TC degradation, and verified the Z-scheme mechanism of the Bi12O17Cl2/Ag/AgFeO2 system.

Tetracycline stress disturbs the mobilization of protein bodies in seed storage reserves during radicle elongation after seed germination.

Residues of antibiotics in the soil can have adverse effects on crop plants related closely to humans. However, there is a lack of knowledge on the phytotoxicity of antibiotics to sensitive species. The aim of our study was mainly to reveal tetracycline stress on the mobilization of seed storage proteins, lipids, and minerals of Chinese cabbage (Brassica rapa L.) during radicle elongation after germination. The Chinese cabbage seed was incubated for 48 h in tetracycline solutions at 1 and 5 µM. For the cotyledons of the seed, the result of TEM showed that tetracycline significantly hindered the mobilization of protein bodies, which was in line with the result of FTIR spectroscopy. However, the mobilization of oil bodies and mineral bodies in cotyledons was not significantly disturbed by the stress of tetracycline, as well as the energy supply in different organs including the cotyledons, hypocotyl, and radicle of the seed. To our knowledge, this is the first study to demonstrate the disturbance on mobilization of protein bodies in seed storage reserves caused by the stress of tetracycline at low levels during radicle elongation after germination.

Dissolved organic matter released from rice straw and straw biochar: Contrasting molecular composition and lead binding behaviors.

It remains debatable whether carbonized straw reapplying is a better solution than direct straw reapplying. Comparison of the characteristics and complexation behaviors of dissolved organic matter (DOM) derived from straw (ST) and biochar (BC) may offer new insights, but little current information exists. Herein, DOM samples were characterized by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), revealing that the molecular weight and condensed aromatic components of BCDOM (457.70 Da and 71.16%, respectively) were higher than those of STDOM (433.48 Da and 3.13%, respectively). In particular, the N-containing compounds of BCDOM was more aromatic than STDOM. By combining spectroscopic techniques, complexation modeling, and chemometric analysis, BCDOM was shown to exhibit higher binding parameters (log KM) and more binding sites for Pb than STDOM. Noteworthily, the two binding sites, aromatic NO and aromatic NO2, existed only in the interaction of BCDOM with Pb. Furthermore, while phenol-OH displayed the fastest response to Pb in both STDOM and BCDOM, the binding sequences were not exactly the same. These differences may be related to the variations in the aromaticity and N-containing structures of DOM detected by FTICR-MS. These findings have implications on the stewardship of straw- and biochar-amended soil.

Revealing the active period and type of tetracycline stress on Chinese cabbage (Brassica rapa L.) during seed germination and post-germination.

Stresses of antibiotics can cause strains (i.e. effects) on seed at germination and post-germination stages. But there is a lack of research on the period and type of the effects at present. In this study, Chinese cabbage (Brassica rapa L.), a commonly used crop, was selected to investigate the effect of tetracycline (TC), a major-use antibiotic, on its seed during different periods of the stages. Results showed that there were no significant differences among the germination energy (GE) of control (CK) and treatments, but radicle length (RL) of the treatments, the exposure to TC at post-germination stage (i.e. radicle elongation stage), was all significantly less than that of CK. The initial stage of radicle elongation was the earliest and most sensitive period at which the stress of TC caused the plastic effect on seed. Moreover, the action of TC stress on seed did not have a delayed characteristic. The result of RL was identical to the leakage of intracellular substances at radicle fast elongation stage, but not the Evan's blue trapped by radicle. We concluded that TC inhibited the elongation of radicle through weakening the cellular metabolic activity rather than leading to the loss of cellular membrane integrity. It should be paid more attention to the phytotoxicity of TC in the field due to its active characteristics revealed in our study.

How climate change and eutrophication interact with microplastic pollution and sediment resuspension in shallow lakes: A review.

Climate change and eutrophication are both critical environmental issues currently. Climate change induces more critical microplastic pollution and sediment resuspension in eutrophic lakes, and conversely the presence of microplastics and resuspension events would intensify these two environmental effects. Via evaluating the impacts of microplastics and sediment resuspension on climate change and eutrophication, it is favorable to provide recommendations for ecological protection and policy formulation in regard to the nutrient input as well as the production and utilization of plastic. In this review, we explore how climate change and eutrophication interact with microplastic pollution and sediment resuspension in shallow lakes, highlighting that both of the latter two play a significant role in the former two. Furthermore, future prospects are put forward on the further and deeper research on the global warming and eutrophication in shallow lakes with microplastic pollution.

Evaluation of tetracycline phytotoxicity by seed germination stage and radicle elongation stage tests: A comparison of two typical methods for analysis.

Biological tests with plant seeds have been adopted in many studies to investigate the phytotoxicity of pollutants to facilitate the control of risks and remain to be optimized. In this work, the experiment with a small sample size (Experiment 1) and the experiment with a large one (Experiment 2) were designed to study the effect of tetracycline (TC) on Chinese cabbage (Brassica rapa L.) at seed germination and radicle elongation stages. At the former stage, germination number data were obtained to analyze the germination energy (GE) and to judge the probability of the number of germinated seeds (Pn) by the binomial distribution model in Experiment 1. While germination time-to-number data were obtained to analyze the mean time to germination (MGT), the estimate of mean time to germination (EMGT) by survival analysis method, the time to germination for 50% of total seeds (T50) and the germination rate (GR) besides GE in Experiment 2. At the latter stage, the data of radicle length (RL) were obtained in all the experiments and the influence from the former stage on this stage was excluded in Experiment 2 but not in Experiment 1. Results showed that TC had universal adverse effects on the latter stage but not on the former stage in the experiments. Considering the availability of germination data for statistical analysis and the robustness of RL data, the methods adopted in Experiment 2 were more feasible than those in Experiment 1. In addition, Chinese cabbage seeds with medium size have the character of rapid germination compared with the commonly used crop species and can be used to shorten the experimental cycle to study the responses of seeds to pollutants to evaluate the phytotoxicity. We introduced survival analysis method to analyze the germination time-to-number data obtained in seed germination test to evaluate the phytotoxicity of tetracycline.

In situ investigation of intrinsic relationship between protonation behavior and HA characteristics in sediments.

Proton-binding study of humic acid (HA) is critical for describing and modeling the binding mechanism of HA with heavy metals. However, little is known about the intrinsic relationship between protonation behavior and HA characteristics, especially in sediments. In this study, HA was extracted from sediments and combination of spectrographic titration with parallel factor analysis, Gaussian fitting model and two-dimensional correlation spectroscopy analysis was developed as a novel in-situ tool. Results indicated that the intensity changes of fluorophores of sediment HA might be dependent on the structure characteristics (fused or non-fused ring) of phenolic species in the protonation process. Compared with phenolic groups (A1, 5.27 ±â€¯0.05 eV; A3, 3.91 ±â€¯0.02 eV), the carboxyl groups (A2, 4.65 ±â€¯0.03 eV) exhibited greater contribution in the response of chromophores to the protonation process of sediment HA. Furthermore, proton binding to sediment HA first occurred in carboxyl groups and then in phenolic groups. The combined technique is a promising approach for the examination of the binding sites, binding capacities, and binding order in proton-HA binding process under environmental concentrations. Importantly, this method is a sensitive, effective and non-destructive technique without any need pre-concentrate.

Where will threatened migratory birds go under climate change? Implications for China's national nature reserves.

Climate change, regarded as one of the major threats to biodiversity and ecosystems, can impact on the distribution and survival of migratory birds. To investigate the threats of climate change to threatened migratory bird distributions, we used species distribution model (SDM) and climatic data under current and future climate scenarios to predict future changes in species distributions and how the geographic distribution of these threatened birds may respond to climate change by 2050. Our results show the hotspots for all species may remain in the lower and middle reaches of the Yangtze River, while more species may dwell in the coastal regions of the Bohai Gulf and the Yellow Sea in the future. Our findings show that the percentage of all species distributions or hotspots for all threatened species covered by national nature reserves (NNRs) in China remain low by 2050. Thus, we propose that China should increase and expand reserves in eastern China. Significantly, we emphasize the creation of protected areas to make it the Ramsar sites in the world and recommend that China should (1) strengthen the cooperation with neighboring countries to share maximum species occurrence data (especially the threatened species), (2) overlay maps of individual species for each taxon to assess the efficiency of coastal nature reserves and predict the hotspots shift under climate change, (3) trade off urban development and ecosystem stability to create new and dynamic protected areas to make it the Ramsar sites, (4) appeal for long-term protection of ecosystem stability to achieve sustainable development in the world.

Integrating priority areas and ecological corridors into national network for conservation planning in China.

Considering that urban expansion and increase of human activities represent important threats to biodiversity and ecological processes in short and long term, developing protected area (PA) network with high connectivity is considered as a valuable conservation strategy. However, conservation planning associated with the large-scale network in China involves important information loopholes about the land cover and landscape connectivity. In this paper, we made an integrative analysis for the identification of conservation priority areas and least-cost ecological corridors (ECs) in order to promote a more representative, connected and efficient ecological PA network for this country. First, we used Zonation, a spatial prioritization software, to achieve a hierarchical mask and selected the top priority conservation areas. Second, we identified optimal linkages between two patches as corridors based on least-cost path algorithm. Finally, we proposed a new framework of China's PA network composed of conservation priority and ECs in consideration of high connectivity between areas. We observed that priority areas identified here cover 12.9% of the region, distributed mainly in mountainous and plateau areas, and only reflect a spatial mismatch of 19% with the current China's nature reserves locations. From the perspective of conservation, our result provide the need to consider new PA categories, specially located in the south (e.g., the middle-lower Yangtze River area, Nanling and Min-Zhe-Gan Mountains) and north regions (e.g., Changbai Mountains), in order to construct an optimal and connected national network in China. This information allows us better opportunities to identify the relative high-quality patches and draft the best conservation plan for the China's biodiversity in the long-term run.