Search

Mercury (Hg) is extremely poisonous and can be absorbed through touch, inhalation, or consumption. In the living environment, Hg in contaminated sediment can be transferred into grass by the direct absorption through the roots or shoots. The intake of Hg due to Hg emissions may pose a threat to living bodies especially to human beings. The present study aims to provide a novel insight about total mercury (THg) and methyl mercury (MeHg) in a riparian grass (Cynodon dactylon (L).Pers) and sediments during the discharging phase (summertime at 145 m water level) in Three Gorges Reservoir (TGR-China); where C. dactylon is a dominant perennial herb in the riparian zone. Yet, the potential risk of Hg contamination in the riparian ecosystem is not thoroughly assessed in the dam regulated reservoir. This study was conducted in the riparian zones of the reservoir formed by a mega dam (Three Gorge Dam) which regulates the water levels during the summer and winter period in the TGR. Our results showed that riparian sediments were acting as a sink for THg and MeHg. Insignificant correlation of THg and MeHg was found between the amphiphyte C. dactylon and its surrounding sediments in the TGR. Bioconcentration factors values for MeHg were found higher than 1 in all study locations in the riparian zones in TGR, which could be due to action of certain bacteria/purely chemical-based methylation on inorganic form of Hg. Additionally, translocation factor indices also highlighted that the amphiphyte C. dactylon was MeHg accumulator in riparian zones. These results suggested that since riparian sediment was found acting as the sink for THg and MeHg during discharging phase, MeHg contamination in the amphiphyte C. dactylon in riparian zones was not caused by the riparian sediments but by other factors, for instance, the anthropogenic activities in the TGR. Finally, this study leads to conclude that amphiphyte C. dactylon can be used as biomonitoring agent for Hg pollution in the TGR.

Metal-organic framework (MOF) is a class of inorganic-organic hybrid material assembled periodically with metal ions and organic ligands. MOFs have always been the focuses in a variety of frontier fields owing to the advantageous properties, such as large BET surface areas, tunable porosity and easy-functionalized surface structure. Among the various application areas, catalysis is one of the earliest application fields of MOFs-based materials and is one of the fastest-growing topics. In this review, the main roles of MOFs in heterogeneous organocatalysis have been systematically summarized, including used as support materials (or hosts), independent catalysts, and sacrificial templates. Moreover, the application prospects of MOFs in photocatalysis and electrocatalysis frontiers were also mentioned. Finally, the key issues that should be conquered in future were briefly sketched in the final parts of each item. We hope our perspectives could be beneficial for the readers to better understand these topics and issues, and could also provide a direction for the future exploration of some novel types of MOFs-based nanocatalysts with stable structures and functions for heterogeneous catalysis.

Activated carbon fiber (ACF) was used to enhance the UV/Electro-Fenton (UV/EF) system to remove nitrobenzene (NB). Comparative removal of NB by ACF adsorption, electrolysis, and UV photolysis was investigated, which indicated ACF can significantly enhance the UV/EF (ACF) system to remove NB. By using ACF cathode, 98% of NB removal was achieved after 20 min, which was much higher than Ti cathode by 60%. The UV/EF (ACF) system was proved to have the feasibility of mineralization of nitrobenzene by the 90% of TOC removal after 5 h. ACF reuse experiments were carried, and the results showed ACF cathode could be reused for successive 4 runs with just 5% declination of NB removal. The impacts of several key influence factors (current intensity, electrolyte, and O2 flux) were explored. Three different kinds of ACF (ACF0: original ACF; ACFN: treated by ammonia; ACFH: treated by nitric acid), methanol, tert-butyl (TBA) alcohol, phenol, and catalase were involved in the system to study the mechanism of the UV/EF (ACF) system. The results showed the combination of ACF and the UV/EF system could significantly improve the H2O2 production and NB removal. Finally, the comparison of the electrical energy per order (EE/O) values between the UV/EF (ACF) and UV/EF (Ti) system showed that ACF can significantly improve the current efficiency of the UV/EF system.

Throughout continents, reservoirs tend to have elevated methylmercury (MeHg) concentration transformed from mercury (Hg/total Hg). This impact may be pronounced in the reservoir with less velocity of water during the charging period resulted in the deposition of sediments. In sediments on favorable conditions, methylation may be enhanced by the decomposition of flood organic material, which can release Hg and enhance microbial activity. However, much less is known about the transfer ratio of Hg and its form MeHg from sediment to biota in the hydrological reservoir during the dam charging phase. The objective of our study was to understand the interrelationship between total Hg and MeHg in two key components sediment and fish in the reservoir ecosystem. This study was performed at the Three Gorges Reservoir (TGR) located on upstream of the Yangtze River in China. At the TGR charging phase, during winter time, the water level was high due to blockade of water by Three Gorges Dam (TGD). Sediment and fish samples were collected in winter season for total Hg, MeHg, and several ancillary parameters. The results showed that total Hg in sediment samples of the winter season were ranged from 6.2 ± 0.001 to 193.3 ± 0.001 × 10−3 mg/kg, with an average value of 53.76 ± 51.80 × 10−3 mg/kg, and for MeHg was ranged from 12.1 ± 0.04 to 348.7 ± 0.16 × 10−2 ng/g, with an average value of 98.96 ± 93.07 × 10−2 ng/g. Total Hg and MeHg in fish samples of the winter season were from 42.48 ± 6.71 to 166 ± 52.56 ng/g, with an average value of 76.22 ± 31.23 ng/g, and from 21.09 ± 2.31 to 61.60 ± 13.30 ng/g, with an average value of 37.89 ± 11.96 ng/g. The relationship of total Hg and MeHg concentrations in fish to those of sediments from corresponding sites showed a negative relationship. This might include a strong association of total Hg with an inorganic component of sediment (e.g., bound to sulfides or coprecipitated with other metal oxides such as manganese and iron). The average concentration of fish MeHg found in this study, at rates greater than 1.72 g/day, was estimated hazardous to human health. This study concludes sediment was acting as sequestrate for total Hg and MeHg in TGR. The bioaccumulation of total Hg and MeHg in fish was not controlled by sediment further investigation about pathological routes and dietary habits of fish needed to be identified for total Hg and MeHg study in TGR.

The agricultural production in the drawdown zone of Three Gorges Reservoir of China has been gradually attracting people's attention in recent years. As influenced by both excessive farming and artificially regulated water level fluctuation, the environmental sustainability of the agricultural system in the drawdown zone is being concerned widely with its production mode and increasing use of agricultural chemicals. Emergy method was used in this study to evaluate the environmental performance of the three agricultural production systems, i.e., cropping, poultry rearing, and fish raising system in the drawdown zone of Three Gorges Reservoir of China. Additionally, to attain a comprehensive understanding of the driving force of respective system's production, some economic indicators are selected to learn the economical efficiency of the three systems referred. The results indicate that the purchased nonrenewable resource accounts for a major portion in cropping production, whereas the renewable resource input constitutes the main part in poultry rearing and fish raising systems. The emergy yield ratio (EYR), environmental loading ratio (ELR), emergy sustainability index (ESI), and economic output/input ratio indicate that the cropping system is less well performed than the poultry rearing and fish raising systems on environmental sustainability, albeit with a relatively higher economic output and net profit. To achieve an environmental sustainable agricultural production, green and clean energy should be advocated to use in the cropping system. At the same time, the government should provide some policy supports to develop an intensive poultry rearing and fish raising productions for raising local farmers' income. Besides, it should be noted that, a controversy about whether the drawdown zone land should be used or not is gradually becoming a social dilemma in Three Gorges Reservoir area. In the long run, the cooperation between the government and local farmers is crucial for alleviating this contradiction, whereby the drawdown zone area's agricultural production could achieve a sustainable development with a light environmental impact.

Removal of nitrobenzene (NB), a carcinogenic and refractory pollutant, in aqueous solution by adsorption, ozonation, electrolysis, and electro-peroxone (E-peroxone) with activated carbon fiber (ACF) was investigated, respectively. Kinetic analyses of NB removal by all the processes followed pseudo-first-order kinetics and the Kapp of E-peroxone-ACF was 14.90 × 10−2 min−1, which was much higher than the others. Besides, the Kapp of E-peroxone-ACF process reduces slightly to 12.18 × 10−2 min−1 even after 100 times of ACF recycle, showing a sustainable activity. Moreover, according to the pore texture characteristics, surface functional groups, FTIR, and SEM images, E-peroxone process does not considerably alter the ACF surface, whereas ozone alone can cause substantial damage to it. These results suggested that ACF was induced from an initiator/a promoter into an electrocatalyst in ozonation by free electrons injection. Moreover, comparing with titanium cathode, ACF can remarkably improve the removal of NB in E-peroxone due to the synchronous adsorption of pollutants and ozone as well as the enhancement of H2O2 generation. It indicates that the ACF cathode is a promising material for organic pollutants removal in the E-peroxone process.

The presence of shadows in optical satellite images limits the application of remote-sensing technology. It is important to restore shadow radiance information for improving information extraction from remote-sensing images. Several shadow-restoration methods have been developed using complex statistical relationships between shadowed areas and their nearby sunlit areas. In this study, a simple shadow-restoration approach was proposed based on the surface reflectance equality relationship RER under the assumption that the surface reflectance of a feature in the shadowed area is equal to that of the same feature in the nearby sunlit area. This approach reduces the number of parameters, thus reducing the error propagated by the uncertainties of extra parameters. The new RER method was tested with three multispectral images with different shadow features. By comparing RER with the widely used mean and variance transformation, the RER was shown to be capable of restoring the image colours, texture, tone, and brightness of the shadowed areas to a visually satisfactory level. Quantitative analysis suggests that RER can help to restore the reflectance of shadow features accurately and has robust performance for a variety of land-surface types. Moreover, RER can be effectively used to restore the spectral shape information of shadow features, which is particularly important when applying RER to the restoration of multispectral imagery for the purpose of image classification.

BiOCl has recently drawn considerable attention for its unique and excellent optical, electrical, mechanical, magnetic properties and photocatalytic performances. We modified the conventional solvothermal method to a simple, rapid and environment-friendly microwave-assisted method to prepare high-quality BiOCl nanoplates, which not only exhibited good purity, crystallinity but also possessed an excellent adsorption activity and visible-light photocatalytic activity for dye Rhodamine B (RhB). The prepared composite was characterized through Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) and UV–vis-DRS to analyze the morphology, crystal structure, surface properties and optical property. The results showed that as-produced BiOCl nanoplates had a high purity, crystallinity and a high percentage of exposed {001} facet, and exhibited a strong adsorption and photocatalytic activity with the adsorption capacity of 6.05–8.81 mgRhB/gBiOCl. Moreover, it was found that the photocatalytic degradation for RhB by using as-produced BiOCl agreed with zero-order reaction kinetics, and the reaction rate constant k was firstly evaluated to be 1.11 h −1 at 22 °C.

A completely non-chromatographic and highly large-scale adaptable synthesis of zirconium poly(styrene-phenylvinylphosphonate)phosphate-supported L-proline (ZrPS-PVPA-Pr) has been developed in only three steps overall. Catalyst 1c was determined to be efficient for the asymmetric direct aldol reaction (only 0.5 mol% of 1c was used) in the presence of water at room temperature, with an enantiomeric excess as high as 99%. In addition, water was identified as one of the most significant reaction condition parameters due to the characteristics of the organic–inorganic hybrid catalyst support. Catalyst 1c was easily recovered by simple filtration and could be reused at least six times with little loss of activity and enantioselectivity. Catalyst 1c can be used efficiently on a large-scale while maintaining the enantioselectivities of the aldol reactions. Therefore, this method has the potential for application in industry.

Gaseous nitrogen (N) losses are mainly responsible for low N use efficiency of applied fertilizers and their derivative environmental hazards, while N application rates and soil water regime are important factors regulating these N processes. In this study, gaseous N losses via ammonia volatilization (AV) and denitrification, determined by sponge trapping-KCl extraction and acetylene inhibition-soil core incubation, respectively, were investigated under different coupled water-N management practices with a winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) rotation system in the Huang-Huai-Hai Plain. Ammonia volatilization after urea application, particularly after topdressing during maize growing seasons, was the dominant gaseous N loss, amounting up to 53.2 kg N ha−1 (38.6 % of the applied N). Ammonia volatilization generally decreased by increasing irrigation rate applied immediately after fertilization. Denitrification N losses were lower than ammonia-N losses, accounting for 1.3 to 18.7 kg N ha−1 year−1, with more than 90 % occurring during the maize growing seasons. Total gaseous N losses showed a significant (P

Forward osmosis (FO) is an emerging technology, however the internal concentration polarization (ICP) problem needs to be resolved in order to improve the water flux. Hydrophobic/hydrophilic interpenetrating network composite nanofibers (HH-IPN-CNF) was used for FO membrane support layer, which was successfully designed and fabricated by electrostatic spinning technology. Hydrophobic polymer is polyethylene terephthalate (PET) and hydrophilic polymer is polyvinyl alcohol (PVA). The FO membrane flux has a significant increase due to the HH-IPN-CNF support layer. The membrane flux improved with the increase of PVA nanofiber content in the HH-IPN-CNF support layer. When the ratio of PET/PVA composite nanofibers was 1/4, the FO membrane exhibited the highest water flux (47.2 LMH) and low salt leakage (9.5 gMH). In the test, deionized (DI) water was used as feed solution (FS), and 0.5 M NaCl solution was used as draw solution (DS) in the mode of active layer facing DS. The improvement of FO flux was attributed to the increase of wetting performance of support layer and the water-transferring function. The existence of the HH-IPN-CNF structure formed between PET and PVA nanofibers leads to the reduction of the ICP. The FO membranes with HH-IPN-CNF support layer achieved a significant increase in water flux.

The transpiring wall reactor (TWR) is considered to be one of the most promising reactors because it minimizes both corrosion and salt precipitation problems that seriously hinder the industrialization of supercritical water oxidation technologies. A transparent reactor is built to study the fluid dynamics of transpiring flow, which are the foundation of reactor design and optimization. The results showed that the transpiring flow is anisotropic with respect to the surface of the transpiring wall due to both the static pressure and viscous resistance. Finally, the novel idea of using air as the transpiring fluid instead of water is presented in an attempt to alleviate current TWR problems such as high energy consumption, high volume of pure water consumption, and temperature fluctuation in the reaction area. A series of experiments and theoretical derivations demonstrate that this novel idea is feasible.

Due to the unique optical properties and excellent biological applications, carbon-based luminescent materials have become a research hotspot in recent years. In this paper, we report a synthesis method under mild condition, in which Carbon NanoCrystals (CNCs) were first prepared, and then high-purity multi-color carbon dots (HPMCCDs) were synthesized by modulating crystal morphology. The prepared nonfluorescent CNCs are, respectively, dissolved in a strong polar solvent and a weak polar solvent to prepare HPMCCDs. It exhibits the multi-excitation and multi-emission features (from green to yellow). The high-purity carbon dots (HPCDs) prepared by using this method demonstrate the higher quantum yields (QYs) (53.7%) than that of the carbon dots (CD) by traditional hydrothermal methods with dialysis, and make full use of the atomic economic model. Besides, it shows the unique up-conversion luminescence property (UCLP) at lower wavelength excitation and, which can also be placed for a long time at room temperature without being oxidized or deteriorated. Furthermore, we explored the regulation of polar-chromism mechanism of the CNCs. Finally, the HPMCCDs can be used for multi-color bioimaging in vivo and in vitro and as well as many other potential applications.

International audience; AbstractBiofortification is a strategy for overcoming human zinc (Zn) deficiency, especially in rural areas of developing countries. Actually, biofortification by foliar Zn application has been demonstrated at small scale, but not at large scale due to the absence of economic analysis. Therefore, here, we conducted the first cost-effectiveness analysis using the method of “disability-adjusted life year” measuring the health burden. We thus quantified the cost of agronomic biofortification of wheat with Zn in three major wheat-growing regions of China. Our results show that the current annual health burden due to human Zn deficiency, defined as numbers of disability-adjusted life years lost, is 0.21 million years for the region under single wheat plantation, 0.79 million years for the region under wheat-maize rotation, and 0.38 million years for the region under wheat-rice rotation. Comparing with traditional wheat diets in these three regions, the consumption of agronomically Zn-biofortified wheat diets could increase the daily Zn intakes of infants and children under 5 years of age. These increased daily Zn intakes consequently reduce the health burden due to human Zn deficiency in these regions by up to 56.6 %. According to cost-effectiveness analysis, the cost for saving one disability-adjusted life year in these regions ranges from US$ 226 to US$ 594 for foliar Zn application alone. The cost ranges from US$ 41 to US$ 108 when foliar Zn and pesticide applications are combined to reduce labor costs. This cost of US$ 41–108 under the combined application of foliar Zn plus pesticide is lower than the World Bank’s standard.

Carboxymethyl cellulose (CMC) stabilized microscale iron sulfide (FeS) particles were synthesized and applied to remediate hexavalent chromium (Cr(VI)) spiked soil. The effects of parameters including dosage of FeS particles, soil moisture, and natural organic matter (NOM) in soil were investigated with comparison to iron sulfate (FeSO4). The results show that the stabilized FeS particles can reduce Cr(VI) and immobilize Cr in soil quickly and efficiently. The soil moisture ranging from 40% to 70% and NOM in soil had no significant effects on Cr(VI) remediation by FeS particles. When molar ratio of FeS to Cr(VI) was 1.5:1, about 98% of Cr(VI) in soil was reduced by FeS particles in 3 d and Cr(VI) concentration decreased from 1407 mg kg−1 to 16 mg kg−1. The total Cr and Cr(VI) in Toxicity Characteristic Leaching Procedure (TCLP) leachate were reduced by 98.4% and 99.4%, respectively. In FeS particles-treated soil, the exchangeable Cr fraction was mainly converted to Fe-Mn oxides bound fraction because of the precipitation of Cr(III)-Fe(III) hydroxides. The physiologically based extraction test (PBET) bioaccessibility of Cr was decreased from 58.67% to 6.98%. Compared to FeSO4, the high Cr(VI) removal and Cr immobilization efficiency makes prepared FeS particles a great potential in field application of Cr(VI) contaminated soil remediation.

Di-(2-ethylhexyl) phthalate (DEHP) has the potential to disrupt the thyroid endocrine system, but the underlying mechanism is unknown. In this study, zebrafish (Danio rerio) embryos were exposed to different concentrations of DEHP (0, 40, 100, 200, 400 μg/L) from 2 to 168 hours post fertilization (hpf). Thyroid hormones (THs) levels and transcriptional profiling of key genes related to hypothalamus-pituitary-thyroid (HPT) axis were examined. The result of whole-body thyroxine (T4) and triiodothyronine (T3) indicated that the thyroid hormone homeostasis was disrupted by DEHP in the zebrafish larvae. After exposure to DEHP, the mRNA expressions of thyroid stimulating hormone (tshβ) and corticotrophin releasing hormone (crh) genes were increased in a concentration dependent manner, respectively. The expression level of genes involved in thyroid development (nkx2.1 and pax8) and thyroid synthesis (sodium/iodide symporter, nis, thyroglobulin, tg) were also measured. The transcripts of nkx2.1 and tg were significantly increased after DEHP exposure, while those of nis and pax8 had no significant change. Down-regulation of uridinediphosphate-glucuronosyl-transferase (ugt1ab) and up-regulation of thyronine deiodinase (dio2) might change the THs levels. In addition, the transcript of transthyretin (ttr) was up-regulated, while the mRNA levels of thyroid hormone receptors (trα and trβ) remained unchanged. All the results demonstrated that exposure to DEHP altered the whole-body thyroid hormones in the zebrafish larvae and changed the expression profiling of key genes related to HPT axis, proving that DEHP induced the thyroid endocrine toxicity and potentially affected the synthesis, regulation and action of thyroid hormones.

FeS nanoparticles were synthesized using chemical precipitation method involving sulfide and ferrous solutions. Effects of important synthesis parameters including stabilizer, time taken for titration, horizontal oscillation speed, and initial salt concentration on the size of synthesized FeS nanoparticles were investigated by Orthogonal Array design. Increasing the CMC dosage significantly made the hydrodynamic diameter decrease between 0.05 wt.% and 0.15 wt.% while Na2S titration, oscillation rate, and Na2S concentration did not show significant influence on the hydrodynamic diameter of FeS nanoparticles. The synthesized FeS nanoparticles were characterized by using XRD (X-ray diffraction), TEM (transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy). The as-synthesized FeS nanoparticles had an average size of 25 ± 10 nm and had a better long-term stability after storage for 150 days compared to bare FeS particles. Because of the optimized process parameters, the synthesized FeS nanoparticles had a higher Cr(VI) removal capacity of 683 mg per gram of FeS in comparison to the previously reported cases, and up to 92.48% Cr(VI) was removed from aqueous solutions. The small size, special surface property, and high reactivity make the synthesized FeS nanoparticles a promising tool for the remediation of Cr(VI) contaminated soil and groundwater.

peer-reviewed Small mixer impeller design is not tailored for granulation because impellers are intended for a wide range of processes. The aim of this research was to evaluate the performances of several impellers to provide guidance on the selection and design for the purposes of granulation. Lactose granules were produced using wet granulation with water as a binder. A Kenwood KM070 mixer was used as a standard apparatus and five impeller designs with different shapes and surface areas were used. The efficacy of granulate formation was measured by adding an optically sensitive tracer to determine variations in active ingredient content across random samples of granules from the same size classes. It was found that impeller design influenced the homogeneity of the granules and therefore can affect final product performance. The variation in active ingredient content across granules of differing size was also investigated. The results show that small granules were more potent than larger granules.

The interlayer pores of swelling 2:1 clays provide an ideal 2-dimensional environment in which to study confined fluids. In this paper we discuss our understanding of the structure and dynamics of interlayer fluid species in expanded clays, based primarily on the outcome of recent molecular modelling and neutron scattering studies. Counterion solvation is compared with that measured in bulk solutions, and at a local level the cation-oxygen coordination is found to be remarkably similar in these two environments. However, for the monovalent ions the contribution to the first coordination shell from the clay surfaces increases with counterion radius. This gives rise to inner-sphere (surface) complexes in the case of potassium and caesium. In this context, the location of the negative clay surface charge (i.e. arising from octahedral or tetrahedral substitution) is also found to be of major importance. Divalent cations, such as calcium, eagerly solvate to form outer-sphere complexes. These complexes are able to pin adjacent clay layers together, and thereby prevent colloidal swelling. Confined water molecules form hydrogen bonds to each other and to the clays' surfaces. In this way their local environment relaxes to close to the bulk water structure within two molecular layers of the clay surface. Finally, we discuss the way in which the simple organic molecules methane, methanol and ethylene glycol behave in the interlayer region of hydrated clays. Quasi-elastic neutron scattering of isotopically labelled interlayer CH 3OD and (CH2OD)2 in deuterated clay allows us to measure the diffusion of the CH3- and CH2-groups in both clay and liquid environments. We find that in both the one-layer methanol solvates and the two-layer glycol solvates the diffusion of the most mobile organic molecules is close to that in the bulk solution.