论文检索

总访问量：5120433次

总访客量：272865人

所有论文

25941. 题目: Carbon chemistry of intact versus chronically drained peatlands in the southeastern USA
文章编号: N19082304
期刊: Journal of Geophysical Research: Biogeosciences
作者: C.A. Stricker, J.Z. Drexler, K.A. Thorn, J.A. Duberstein, S. Rossman
更新时间: 2019-08-23
摘要: The Great Dismal Swamp (GDS) is a large temperate swamp in Virginia/North Carolina with peat soils historically resistant to microbial decomposition. However, this peatland has been subject to ~200 years of disturbance during which extensive drainage, fire suppression, and wide‐spread logging have increased decomposition and dramatically decreased the distribution of Atlantic white cedar (AWC). The purpose of this study was to determine the impact of long‐term drainage and AWC loss on the carbon chemistry of GDS peats. Peat cores were collected from three drained GDS vegetation communities (pocosin, AWC, and red maple‐black gum) and compared to cores collected from an intact, undrained AWC peatland at the Alligator River National Wildlife Refuge (AR) in North Carolina, USA. The AR peats had higher lignin content in the deeper peat intervals, and lignin content and % organic carbon were largely invariant with depth compared to the GDS peats. The concentrations of syringyl group phenols were greater in the surface layers of GDS peats, likely reflecting the selective removal of AWC and transition from gymnosperms to angiosperms. Acid to aldehyde ratios for vanillyl and syringyl group phenols indicated that the GDS peats were more decomposed, particularly at depth, and that this occurred under aerobic conditions. Moreover, solid state ¹³C NMR confirmed a coincident loss of carbohydrates and increase in recalcitrant byproducts of carbohydrate degradation with depth. These data indicate that long‐term drainage has accelerated the decomposition of peat at the GDS, reducing the capacity and stability of the carbon sink.

25942. 题目: Electro-Fenton with peroxi-coagulation as a feasible pre-treatment for high-strength refractory coke plant wastewater: Parameters optimization, removal behavior and kinetics analysis
文章编号: N19082303
期刊: Chemosphere
作者: Xin Zhou, Zilong Hou, Lin Lv, Jingjing Song, Zeyang Yin
更新时间: 2019-08-23
摘要: Electro-Fenton (EF) with peroxi-coagulation (PC) as an emerging electro-chemical advanced oxidation method has been extensively applied to treat refractory wastewater. However, the studies on the pretreatment of the raw coke plant wastewater by EF process were still lacking. In this study, a lab-scale EF system (Fe as anode and graphite as cathode) achieved the highest COD removal of 69.2% based on the preliminary experiments. The process parameters and corresponding COD removal performance were further optimized using response surface methodology (RSM) combined with Box-Behnken experimental design (BBD). The optimal conditions were obtained as: 3.2 mA cm⁻² of current density, 2 h of the reaction time and 2.6 of the initial pH value, with the COD removal reaching 70.0%. Fourier infrared (FTIR), fluorescence excitation-emmission matrix (EEM) and gas chromatography-mass spectrometry (GC-MS) also revealed the degradation behaviors of dissolved organic matters (DOMs) by characterizing their structures and compositions before and after EF pretreatment, thus greatly improving the biodegradability of the wastewater. Moreover, the EF process for COD removal well followed third-order kinetics model. These findings give helpful guidance to design, optimize and control the EF process as a favourable pretreatment for actual refractory coking wastewater in practice.
图文摘要:

25943. 题目: Transformation and degradation of recalcitrant organic matter in membrane bioreactor leachate effluent by the O3/H2O2 process
文章编号: N19082302
期刊: Environmental Science: Water Research & Technology
作者: Zhepei Gu, Weiming Chen, Fan Wang, Qibin Li
更新时间: 2019-08-23
摘要: Membrane bioreactor effluent from treating leachate (MBR leachate) is characterized by a high humification degree, and further treatment of refractory organics is required. Refractory organic components in the MBR leachate were identified by using the three-dimensional excitation emission matrix (3D-EEM) coupled with parallel factor (PARAFAC) analysis, namely fulvic-like substances (C1, Ex/Em = (245)325 nm/410 nm) and humic-like substances (C2, Ex/Em = (255)365 nm/460 nm). With a higher O₃ dosage and an increase in H₂O₂ dose, the removal efficiency for C1 and C2 can be enhanced. However, an overdose of H₂O₂ or alkaline conditions exhibited some inhibition of refractory component removal in the O₃/H₂O₂ process. The unsaturated structure of the humic substances was destroyed, and the aromaticity degree, hydrophobicity degree, humification degree, molecular mass, and condensation degree of the benzene ring compounds in the MBR leachate were reduced considerably by the O₃/H₂O₂ process. Therefore, the biodegradability of the MBR leachate increased considerably to 0.32. Correlation analysis, principal component analysis, and linear regression were applied and indicated that the chemical oxygen demand (COD) had a significant positive correlation with C1 and C2, and the absorbance at 254 nm (UV₂₅₄) had a more significant positive correlation with C2. Hence, monitoring and determination of relative C1 and C2 contents can achieve rapid COD prediction in the MBR leachate. This study provides suggestions and guidance for MBR leachate treatment and references for the rapid prediction of refractory organic concentration.
图文摘要:

25944. 题目: Key factors and microscopic mechanisms controlling adsorption of cadmium by surface oxidized and aminated biochars
文章编号: N19082301
期刊: Journal of Hazardous Materials
作者: Ling Zhu, Lihong Tong, Nan Zhao, Xiang Wang, Xixiang Yang, Yizhong Lv
更新时间: 2019-08-23
摘要: Modified biochar has great potential for adsorbing cadmium (Cd) in the aquatic environment, but the micro-immobilization mechanisms, driven by surface modifications, remain unclear. There has been no attempt to determine the key adsorption factors by integrating the numerous physiochemical indicators. In this study, surface oxidized biochar (OPBC) and surface aminated biochar (APBC) were prepared from porous biochar (PBC), and the Cd adsorption mechanisms by the modified biochars at the molecular and electronic scales were investigated. The adsorption capacity of APBC and OPBC for Cd was 23.54 and 19.04 mg g⁻¹, respectively, which was about three times higher than that of PBC. Macroscopically, physicochemical adsorption and intraparticle diffusion dominated the Cd adsorption, and surface properties, such as functional groups, were identified as key factors controlling adsorption. Microscopically, the adsorption of Cd mainly occurred in regions rich in π electrons, lone pair electrons and electron donor groups. The interaction between carboxyl and Cd dominated the adsorption performance of OPBC, while the Cd²⁺-π interaction was weakened by increasing the π electron electrostatic potential of aromatic rings. The lone pair electrons of the amino groups dominated the complexation of APBC with Cd, and the π electron electrostatic potential was almost unaffected.
图文摘要:

25945. 题目: The combined influence of hydrophobicity, charge and molecular weight on natural organic matter removal by ion exchange and coagulation
文章编号: N19082221
期刊: Chemosphere
作者: P. Finkbeiner, G. Moore, R. Pereira, B. Jefferson, P. Jarvis
更新时间: 2019-08-22
摘要: Three different source waters were investigated using virgin and pre-used anion exchange resins, coagulation, and ion exchange combined with coagulation (IEX&Coagulation). The hydrophobicity, size distribution and charge of natural organic matter (NOM) were used to evaluate its removal. Dissolved organic carbon (DOC) removal by pre-used IEX resin was 67–79%. A consistent ratio of different hydrophobicity fractions was found in the removed DOC, while the proportion and quantity of the molecular weight fraction around 1 kDa was important in understanding the treatability of water. For pre-used resin, organic compounds were hypothesised to be restricted to easily accessible exchange sites. Comparatively, virgin resin achieved higher DOC removals (86–89%) as resin fouling was absent. Charge density and the proportion of the hydrophobic fraction were found to be important indicators for the specific disinfection byproduct formation potential (DBP-FP). Treatment of raw water with pre-used resin decreased the specific DBP-FP by between 2 and 43%, while the use of virgin resin resulted in a reduction of between 31 and 63%. The highest water quality was achieved when the combination of IEX and coagulation was used, reducing DOC and the specific DBP-FP well below that seen for either process alone.
图文摘要:

25946. 题目: Composition and superposition of alluvial deposits drive macro-biological soil engineering and organic matter dynamics in floodplains
文章编号: N19082220
期刊: Geoderma
作者: A. Schomburg, D. Sebag, P. Turberg, E.P. Verrecchia, C. Guenat, P. Brunner, T. Adatte, R. Schlaepfer, R.C. Le Bayon
更新时间: 2019-08-22
摘要: Soil structure formation in alluvial soils is a fundamental process in near-natural floodplains. A stable soil structure is essential for many ecosystem services and helps to prevent river bank erosion. Plants and earthworms are successful soil engineering organisms that improve the soil structural stability through the incorporation of mineral and organic matter into soil aggregates. However, the heterogeneous succession of different textured mineral and buried organic matter layers could impede the development of a stable soil structure. Our study aims at improving the current understanding of soil structure formation and organic matter dynamics in near natural alluvial soils. We investigate the effects of soil engineering organisms, the composition, and the superimposition of different alluvial deposits on the structuration patterns, the aggregate stability, and organic matter dynamics in in vitro soil columns, representing sediment deposition processes in alluvial soils. Two successions of three different deposits, silt–buried litter–sand, and the inverse, were set up in mesocosms and allocated to four different treatments, i.e. plants, earthworms, plants + earthworms, and a control. X-ray computed tomography was used to identify structuration patterns generated by ecosystem engineers, i.e. plant root galleries and earthworm tunnels. Organic matter dynamics in macro-aggregates were investigated by Rock-Eval pyrolysis. Plant roots only extended in the top layers, whereas earthworms preferentially selected the buried litter and the silt layers. Soil structural stability measured via water stable aggregates (%WSA) increased in the presence of plants and in aggregates recovered from the buried litter layer. Organic matter dynamics were controlled by a complex interplay between the type of engineer, the composition (silt, sand, buried litter) and the succession of the deposits in the mesocosm. Our results indicate that the progress and efficiency of soil structure formation in alluvial soils strongly depends on the textural sequences of alluvial deposits.

25947. 题目: Straw incorporation influences soil organic carbon sequestration, greenhouse gas emission, and crop yields in a Chinese rice (Oryza sativa L.) –wheat (Triticum aestivum L.) cropping system
文章编号: N19082219
期刊: Soil and Tillage Research
作者: Haihou Wang, Mingxing Shen, Dafeng Hui, Ji Chen, Guofeng Sun, Xin Wang, Changying Lu, Jing Sheng, Liugen Chen, Yiqi Luo, Jianchu Zheng, Yuefang Zhang
更新时间: 2019-08-22
摘要: Crop straw management plays important roles in sustainable agriculture and environmental protection. Straw incorporation has multiple influences on soil organic carbon (SOC) sequestration, greenhouse gas (GHG) emissions, and crop yields, but these influences have rarely been studied simultaneously in a single cropping system. This study was conducted to examine the influence of long-term straw incorporation on the SOC sequestration rate, methane (CH₄) and nitrous oxide (N₂O) emissions and crop yields in a Chinese rice (Oryza sativa L.) –wheat (Triticum aestivum L.) cropping system in Hydragric Anthrosols under a subtropical monsoon climate. Four straw incorporation treatments were applied: wheat straw incorporation only (WS), rice straw incorporation only (RS), both wheat and rice straw incorporation (WSRS), and no straw incorporation (as a control). The SOC sequestration rate was estimated from the changes in SOC stock in the topsoil (0–20 cm) from 2007 to 2016. The emissions of CH₄ and N₂O were measured every 7 d when possible using a static chamber method from the 2013 rice season to the 2016 wheat season. Our results showed that the straw incorporation treatments significantly influenced the seasonal CH₄ and N₂O emissions and rice yield but had no influence on wheat yield. Straw incorporation significantly increased the annual topsoil SOC sequestration rate by 0.24–0.43 t C ha⁻¹ yr⁻¹ and the annual CH₄ and N₂O emissions by 44–138 kg CH₄-C ha⁻¹ yr⁻¹ and 0.68–1.49 kg N₂O-N ha⁻¹ yr⁻¹, respectively. Relative to the RS treatment, the WS and WSRS treatments significantly increased annual CH₄ emissions by 38% and 61%, respectively. Relative to the RS treatment, the WSRS treatment significantly increased the annual N₂O emissions, by 35%. The average annual yields were significantly higher in the WSRS (16.8 t ha⁻¹ yr⁻¹) and RS (16.7 t ha⁻¹ yr⁻¹) treatments than in the WS (15.7 t ha⁻¹ yr⁻¹) and control (15.2 t ha⁻¹ yr⁻¹) treatments. Across the three rotation cycles, the annual net global warming potential and greenhouse gas intensity were similar between the control and RS treatments but were significantly lower in these treatments than in the WSRS and WS treatments. These findings suggest that the RS treatment can simultaneously increase crop yields and environmental sustainability in rice–wheat cropping systems.

25948. 题目: Phaeodaria: an important carrier of particulate organic carbon in the mesopelagic twilight zone of the North Pacific Ocean
文章编号: N19082218
期刊: Global Biogeochemical Cycles
作者: Takahito Ikenoue, Katsunori Kimoto, Yusuke Okazaki, Miyako Sato, Makio C. Honda, Kozo Takahashi, Naomi Harada, Tetsuichi Fujiki
更新时间: 2019-08-22
摘要: Phaeodaria, which comprise one group of large, single‐celled eukaryotic zooplankton, have been largely ignored by past marine biological studies because Phaeodaria and their delicate skeletons are liable to collapse. As a result, collection and quantification of specimens are difficult, and seasonal changes of phaeodarian abundance have not been thoroughly studied. The transport of biogenic elements by sinking phaeodarians has been estimated for only a few representative species. Sinking particles >1 mm in size and swimmers have traditionally been excluded when estimating sinking particle fluxes. The focus of this study is the large number of phaeodarians among the >1 mm sinking particles collected in the western North Pacific from June 2014 to July 2015. Careful sorting by microscopic examination and chemical analyses revealed that phaeodarians accounted for up to about 10% of the organic carbon in all sinking particles and accounted for a mean of 33% of the organic carbon in the >1 mm sinking particles. The high standing stocks of phaeodarians at depths of 150–1000 m in the mesopelagic twilight zone suggested that particles sinking from the euphotic zone as aggregates and fecal pellets can be efficiently ex to the deep sea by the ballasting effect of large phaeodarian particles rich in organic carbon.

25949. 题目: Assessing the influence of soil abiotic and biotic factors on Nostoc commune inoculation success
文章编号: N19082217
期刊: Plant and Soil
作者: B. Roncero-Ramos, J. R. Román, E. Rodríguez-Caballero, S. Chamizo, P. Águila-Carricondo, P. Mateo, Y. Cantón
更新时间: 2019-08-22
摘要: Aims: A possible approach to restore drylands is to recover biocrusts by inoculating cyanobacteria. Many studies have demonstrated the ability of cyanobacteria to successfully colonize soil and improve its functions. However, most studies have focused on the abiotic factors influencing the inoculation success, overlooking biotic factors. We examined the influence of the soil indigenous community on the inoculated cyanobacteria by sterilizing soils and analyzing its effects on several key soil properties. Methodology: Nostoc commune was inoculated under laboratory conditions on two soil types with different levels of degradation and under two watering frequencies. All treatments were carried out in natural and sterilized soils. Results: The analysis of the cyanobacterial coverage (30–50% in all inoculated soils), chlorophyll a, visible albedo, roughness, water repellency, organic carbon (OC) and exopolysaccharides (EPS) content showed that cyanobacterial inoculation succeeded, improving soil properties that varied depending on the soil type. The sterilization of soils had little effect: in less degraded soils, the results suggest a faster growth of the indigenous community reaching coverage values of 10% and an interaction with the inoculum that led to a decrease in 2 and 0.3 g Kg⁻¹ of OC and TB-EPS, respectively; in more degraded soils, the community reduced the cyanobacterial coverage around 11%, suggesting competitive interactions. Conclusions: N. commune can be employed to restore lifeless soils. Also, the analysis of native soil community should be considered before field inoculation to plan appropriate methodologies.

25950. 题目: Evaluation of the adsorption potential of biochars prepared from forest and agri-food wastes for the removal of fluoxetine
文章编号: N19082216
期刊: Bioresource Technology
作者: Maria João Fernandes, Manuela M. Moreira, Paula Paíga, Diogo Dias, Maria Bernardo, Manuela Carvalho, Nuno Lapa, Isabel Fonseca, Simone Morais, Sónia Figueiredo, Cristina Delerue-Matos
更新时间: 2019-08-22
摘要: Twelve biochars from forest and agri-food wastes (pruning of Quercus ilex, Eucalyptus grandis, Pinus pinaster, Quercus suber, Malus pumila, Prunus spinosa, Cydonia oblonga, Eriobotrya japonica, Juglans regia, Actinidia deliciosa, Citrus sinensis and Vitis vinifera) were investigated as potential low-cost and renewable adsorbents for removal of a commonly used pharmaceutical, fluoxetine. Preliminary adsorption experiments allowed to select the most promising adsorbents, Quercus ilex, Cydonia oblonga, Eucalyptus, Juglans regia and Vitis vinifera pruning material. They were characterized by proximate, elemental and mineral analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, determination of specific surface area and pH at the point of zero charge. Batch and equilibrium studies were performed, and the influence of pH was evaluated. The equilibrium was reached in less than 15 min in all systems. The maximum adsorption capacity obtained was 6.41 mg/g for the Eucalyptus biochar, which also demonstrated a good behavior in continuous mode (packed column).
图文摘要:

25951. 题目: Surface water treatment by UV/H2O2 with subsequent soil aquifer treatment: impact on micropollutants, dissolved organic matter and biological activity
文章编号: N19082215
期刊: Environmental Science: Water Research & Technology
作者: Robin Wünsch, Julia Plattner, David Cayon, Fabienne Eugster, Jens Gebhardt, Richard Wülser, Urs von Gunten, Thomas Wintgens
更新时间: 2019-08-22
摘要: Because organic micropollutants (MP) are frequently detected in river waters that are used as drinking water sources, combining a relatively cost-efficient natural treatment with upstream advanced oxidation processes (AOP) appears promising for their efficient abatement. Such a multi-barrier system can be integrated in drinking water production schemes to minimize risks from potentially hazardous MPs. This study investigates the impact of an UV/H₂O₂ AOP before soil aquifer treatment (SAT) on the abatement of selected MPs (EDTA, acesulfame, iopamidol, iomeprol, metformin, 1H-benzotriazole, iopromide), dissolved organic matter (DOM) (apparent molecular size distribution, specific UV absorbance at 254 nm – SUVA) and microbial parameters (intact cell count, cell-bound ATP). A pilot plant consisting of an AOP (0.5 m³ h⁻¹, 4 mg L⁻¹ H₂O₂, 6000 J m⁻²) and two parallel soil columns (filtration velocity: 1 m d⁻¹, column height: 1 m) was continuously operated over a period of 15 months with Rhine river water pre-treated with rapid sand filtration. The investigations revealed a shift towards longer retention times of the humic substances peak in LC analysis of DOM, lower SUVA and higher biodegradability of DOM after UV/H₂O₂ treatment. In addition, an overall higher abatement of all investigated MPs by the combined treatment was observed (AOP with subsequent SAT) compared to either process alone. This observation could be explained by an addition of the single treatment effects. The strong primary disinfection effect of the AOP was detectable along the first meter of infiltration, but did not lead to any change in the column performance (i.e., similar abatement of dissolved organic matter).
图文摘要:

25952. 题目: Changes in the stocks of soil organic carbon, total nitrogen and phosphorus following afforestation of post-arable soils: A chronosequence study
文章编号: N19082214
期刊: Forest Ecology and Management
作者: Halina Smal, Sławomir Ligęza, Jacek Pranagal, Danuta Urban, Dorota Pietruczyk-Popławska
更新时间: 2019-08-22
摘要: The objective of this study was to investigate the effect of afforestation of post-arable sandy soils (Dystric Arenosols) with Scots pine (Pinus sylvestris L.) on the amount and distribution of C_org, N_tot and P_tot stocks between genetic soil horizons. The study was performed at three locations with five classes of afforestation each: 10-, 20-, 30-, 40-, 50-year-old stands, which additionally included the arable and the continuous forest soils as reference. The soil was sampled by genetic horizon, including the organic one, down to 100 cm, from its whole thickness, and from A horizon of the afforested soils from: 0–5, 5–10 and 10–20 cm. In the organic horizon of the afforested soils, the stock of C_org, N_tot and P_tot increased significantly with stand age, and an average rate of accumulation was 33.6, 1.30 and 0.04 g m⁻² year⁻¹ respectively. C_org stocks in the former plough layer were found to decrease within the first decade of afforestation, and subsequently, the values gradually increased. With organic horizon included the respective stocks reached the level comparable with the related horizon of the arable soil after approx. 20–30 years. Subsoil B, BC and C horizons together accounted for approx. 35% of the C_org stocks in the entire profile. N_tot stocks in mineral soil horizons initially dropped in the first decade after afforestation, which was subsequently followed by an increase; however, after 50 years, still the observed values were lower in comparison with both the respective arable and continuous forest soils. P_tot stocks in the mineral soil horizon declined over the chronosequence, and in the profile at 50-year-old stands, they were lower in comparison with both the arable and the continuous forest soils. Stand age and sampling by genetic horizons, including the organic horizon, from the entire soil profile should be considered for estimation of changes in C_org, N_tot and P_tot stocks following afforestation of agricultural soils.

25953. 题目: Biochar produced from the co-pyrolysis of sewage sludge and walnut shell for ammonium and phosphate adsorption from water
文章编号: N19082213
期刊: Journal of Environmental Management
作者: Qianqian Yin, Mengtian Liu, Huaipu Ren
更新时间: 2019-08-22
摘要: Pyrolysis of sewage sludge to obtain biochar is an environmentally friendly method of sewage sludge utilization. In this study, sewage sludge and walnut shell were co-pyrolyzed to produce biochar, which was utilized in the adsorption of ammonium and phosphate from water. Brunauer–Emmett–Teller analysis, X-ray diffraction spectroscopy, scanning electron microscopy, and Fourier transform infrared techniques were applied to analyze the physical and chemical properties of the biochar. The sewage sludge-based biochar consisted of rich metal oxides and functional groups, and the addition of walnut shell was beneficial for the development of porous structure. When the mixing ratio of sewage sludge and walnut shell was 3:1, the derived biochar (MBC3-1) showed a high adsorption capacity for NH4 in neutral or weak alkaline water. Pure sewage sludge biochar (SBC) was the best option for the adsorption of PO43 in a wide pH range of water. The adsorption of NH4 and v on MBC3-1 and SBC were controlled by intraparticle diffusion and pseudo-second-order kinetic models, respectively. Isothermal studies indicated that multiple adsorption processes occurred in the adsorption of NH4 and PO43, and the maximum adsorption capacity of NH4 and PO43 reached 22.85 mg/g and 303.49 mg/g on MBC3-1 and SBC, respectively. Thermodynamic analysis confirmed the exothermic and endothermic nature for NH4 and PO43 adsorption on biochar, respectively.
图文摘要:

25954. 题目: Optimizing sludge dewatering with a combined conditioner of Fenton's reagent and cationic surfactant
文章编号: N19082212
期刊: Journal of Environmental Sciences
作者: Dong-Qin He, Jing-Yi Chen, Bo Bao, Xiang-Liang Pan, Jun Li, Chen Qian, Han-Qing Yu
更新时间: 2019-08-22
摘要: Enhancing sludge dewatering is of importance in reducing environmental burden and disposal costs. In this work, a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), was combined with Fenton's reagent for sludge dewatering. Results show that the Fenton-CTAB conditioning significantly promotes the sludge dewatering. Using combined techniques of response surface methodology and uniform design, dosages of Fe²⁺, H₂O₂, and CTAB for water content response were optimized to be 89, 276, and 233 mg/g dry solids (DS), respectively. The water content of sludge decreased from 79.0% to 66.8% under the optimal conditions. Compared with cationic polyacrylamide, the Fenton-CTAB system exhibited superior sludge dewatering performance. To gain insights into the mechanisms involved in sludge dewatering, the effects of Fenton-CTAB conditioning on the composition of extracellular polymeric substances (EPS) and the morphology of the sludge flocs were investigated. The decomposition of EPS into some dissolved organics and the release of proteins in tightly bound EPS facilitated the conversion of bound water to free water and further reduced the water content of sludge cake. After conditioning, morphology of sludge showed aggregation. Overall, the enhanced sludge dewatering by Fenton-CTAB treatment provides an efficient way for management of sewage sludge.
图文摘要:

25955. 题目: Photocatalytic degradation of gemifloxacin antibiotic using Zn-Co-LDH@biochar nanocomposite
文章编号: N19082211
期刊: Journal of Hazardous Materials
作者: Peyman Gholami, Alireza Khataee, Reza Darvishi Cheshmeh Soltani, Laleh Dinpazhoh, Amit Bhatnagar
更新时间: 2019-08-22
摘要: The purpose of the present study was to investigate the photocatalytic performance of biochar (BC)-incorporated Zn-Co-layered double hydroxide (LDH) nanostructures in gemifloxacin (GMF) degradation as a pharmaceutical pollutant. The as-prepared Zn-Co-LDH@BC showed high photocatalytic performance due to the enhanced separation of photo-generated charge carriers using cobalt hydroxide as well as inhibiting the agglomeration of LDH nanostructures by incorporation of BC. According to the results, 92.7% of GMF was degraded through photocatalysis in the presence of Zn-Co-LDH catalyst. The photocatalytic performance of BC-incorporated Zn-Co-LDH was highly dependent on the solute concentration and photocatalyst dosage. The addition of ethanol caused more inhibiting effect than that of benzoquinone (BQ), indicating the major role of ^•OH in decomposition of GMF compared to the negligible role of O₂^•−. A greater enhancement in the photocatalytic degradation of GMF was obtained when the photoreactor containing Zn-Co-LDH@BC nanostructures was oxygenated. Less than 10% drop in the removal efficiency of GMF was observed within five successive operational runs. The results of chemical oxygen demand (COD) analysis indicated the COD removal efficiency of about 80% within 200 min, indicating the acceptable mineralization of GMF. The reaction pathways were also proposed for the photocatalytic conversion of GMF under UV light irradiation.
图文摘要:

25956. 题目: Tetracycline removal by double-metal-crosslinked alginate/ graphene hydrogels through an enhanced Fenton reaction
文章编号: N19082210
期刊: Journal of Hazardous Materials
作者: Yan Kong, Yuan Zhuang, Baoyou Shi
更新时间: 2019-08-22
摘要: Polymer hydrogels usually has limited catalytic activity and stability in catalysis. Here, we presented for the first time the preparation of a novel double-metal-crosslinked alginate hydrogel using graphene oxide to facilitate the Fe(II)/Fe(III) redox cycles. Five multivalent metal cations were used as crosslinkers to prepare different alginate-GO-M (Fe(III), Fe(II), La(III), Ce(III), and Co(II)), and the effects of assisted metal cations (La(III), Ce(III), and Co(II)) on different Fe(II) bimetallic alginate-GO-Fe-M(AG-Fe-M) complexes were investigated. Double-metal-crosslinked alginate-GO hydrogels can degrade tetracycline much faster during the initial 10 min than single-metal-crosslinked hydrogels. In addition, the release of iron from AG-Fe-Ce (10.59 ppm) is less than that from AG-Fe-Co (21.57 ppm) and AG-Fe-La (25.6 ppm) during the Fenton reaction. More importantly, the AG-Fe-Ce does not release TOC and maintains most of the catalytic activity after four reuse cycles, confirming its excellent stability. For the treatment of raw water containing a high proportion of proteinaceous matter and tetracycline, the AG-Fe-Ce significantly reduces the molecular weight of the dissolved organic matter. We deduced that the humic acid and protein show good complexation ability to tetracycline, thereby reducing its bioavailability. This study provides new insights into the synthesis of polymer catalysts for water treatment.
图文摘要:

25957. 题目: Mobilization and transformation of arsenic from ternary complex OM-Fe(III)-As(V) in the presence of As(V)-reducing bacteria
文章编号: N19082209
期刊: Journal of Hazardous Materials
作者: Xiaolin Cai, Pengfei Wang, Zejiao Li, Yan Li, Naiyi Yin, Huili Du, Yanshan Cui
更新时间: 2019-08-22
摘要: Organic matter (OM) was proved to have a high affinity for arsenic (As) in the presence of ferric iron (Fe(III)), the formed ternary complex OM-Fe(III)-As(V) were frequently studied before; however, the mobilization and transformation of As from OM-Fe(III)-As(V) in the presence of As(V)-reducing bacteria remains unclear. Two different strains (Desulfitobacterium sp. DJ-3, Exiguobacterium sp. DJ-4) were incubated with OM-Fe(III)-As(V) to assess the biotransformation of As and Fe. Results showed that Desulfitobacterium sp. DJ-3 could substantially stimulate the reduction and release of OM-Fe complexed As(V) and resulted in notable As(III) release (30 mg/L). The linear combination fitting result of k³-weighted As K-edge EXAFS spectra showed that 56% of OM-Fe-As(V) was transformed to OM-Fe-As(III) after 144 h. Besides, strain DJ-3 could also reduce OM complexed Fe(III), which lead to the decomposition of ternary complex and the release of 11.8 mg/g Fe(II), this microbial Fe(III) reduction process has resulted in 11% more As liberation from OM-Fe(III)-As(V) than without bacteria. In contrast, Exiguobacterium sp. DJ-4 could only reduce free As(V) but cannot stimulate As release from the complex. Our study provides the first evidence for microbial As reduction and release from ternary complex OM-Fe(III)-As(V), which could be of great importance in As geochemical circulation.
图文摘要:

25958. 题目: Monsoon-influenced variation of clay mineral compositions and detrital Nd-Sr isotopes in the western Andaman Sea (IODP Site U1447) since the late Miocene
文章编号: N19082208
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Jongmin Lee, Sunghan Kim, Jae Il Lee, Hyen Goo Cho, Stephen C. Phillips, Boo-Keun Khim
更新时间: 2019-08-22
摘要: Nd-Sr isotopes (ε_Nd, ⁸⁷Sr/⁸⁶Sr) of detrital particles, clay mineral compositions, and δ¹³C of sediment organic matter (δ¹³C_SOM) at the International Ocean Discovery Program (IODP) Expedition 353 Site U1447 in the western Andaman Sea were measured to reveal the sediment provenance changes and/or weathering intensity variations in association with the Indian monsoon intensity change. The shipboard age model based on biostratigraphic data and paleomagnetic reversals shows that IODP Site U1447 preserves late Miocene (~10 Ma) sediments. Nd/Sr isotope systematics demonstrates that the sediments originated mainly from the Myanmar region, including the Irrawaddy River, Salween River, Sittang River and Indo-Burman-Arakan Ranges without a significant change of sediment provenance since the late Miocene. Thus, temporal variations of clay mineral compositions, represented as smectite/(illite + chlorite) [S/(I + C)], indicate the long-term variations of physical/chemical weathering intensity attributable to intensity changes of Indian winter/summer monsoon. A gradual decreasing trend of S/(I + C) ratios indicates stronger physical and/or weaker chemical weathering since the late Miocene, as a result of strengthening of Indian winter monsoon (and/or weakening of Indian summer monsoon), which seems be closely related to global cooling since the late Miocene. Distinct decrease of S/(I + C) ratios occurred at ~9.2–8.5 Ma, ~3.6 Ma, ~2.4 Ma, and ~1.2 Ma, which may be attributed to the combined effect of both global cooling and Tibetan Plateau Uplift as a local response. In addition, δ¹³C_SOM values at IODP Site U1447 were higher at ~3.5 Ma and after 1.5 Ma when S/(I + C) ratio was minima, which may imply an increase of C₄ plant in Myanmar region as a result the strong Indian winter monsoon (or weak Indian summer monsoon).

25959. 题目: Did early land plants produce a stepwise change in atmospheric oxygen during the Late Ordovician (Sandbian ~458 Ma)?
文章编号: N19082207
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Y. Datu Adiatma, Matthew R. Saltzman, Seth A. Young, Elizabeth M. Griffith, Nevin P. Kozik, Cole T. Edwards, Stephen A. Leslie, Alyssa M. Bancroft
更新时间: 2019-08-22
摘要: A stepwise change in atmospheric oxygen (O₂) levels during the Ordovician has been attributed to the emergence of land plants. This phenomenon is tied to a major baseline shift in the stable carbon isotope (δ¹³C) curve and inferred increase in nutrient delivery and enhanced primary productivity in nearshore settings, which led to high organic carbon burial. The timing and magnitude of this baseline shift, however, is still elusive in part because of the lack of high-resolution δ¹³C data that span this period. Much of the existing Ordovician δ¹³C literature is focused on isotopic excursions with less emphasis on identifying long-term shifts in baseline (pre- and post-excursion) values.This study presents new high resolution δ¹³C data from stratigraphic sections at Germany Valley (West Virginia) and Union Furnace (Pennsylvania) in the Central Appalachian Basin. These sections span the entire Sandbian Stage and continue into the lower Katian Stage. The δ¹³C data from both sections are characterized by relative stability carbon isotope values (mean = −0.61‰) in the lower Sandbian, followed by a + 1.2‰ shift in the upper Sandbian (mean = +0.62‰). Herein, we propose that the positive shift represents a long-term global shift in baseline δ¹³C values of dissolved inorganic carbon. The timing of this positive shift coinciding with the diversification of early land plants (i.e., bryophytes) supports earlier models that suggested enhanced organic carbon burial rates served as a mechanism for the stepwise oxygenation of the atmosphere during the Late Ordovician.

25960. 题目: Octadecylamine degradation through catalytic activation of peroxymonosulfate by FeMn layered double hydroxide
文章编号: N19082206
期刊: Science of The Total Environment
作者: Gong Chen, Li-chao Nengzi, Bo Li, Yingjie Gao, Guixian Zhu, Xiuwen Cheng
更新时间: 2019-08-22
摘要: A kind of heterogeneous catalyst, FeMn layered double hydroxide (Fe-Mn-LDH), was fabricated by coprecipitation process and used as PMS activator to degrade a novel organic pollutant octadecylamine (ODA). And the X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microcopy (TEM), Mapping and X-ray photoelectron spectra (XPS) measurements were utilized to characterize the fresh and used Fe-Mn-LDH. After a serious of degradation experiments, it was clearly to see that the activator possessed excellent activation property for PMS and was capable of removing 85% ODA (10 mg·L⁻¹) within 25 min obviously higher than pure PMS. Moreover, the effect of some elements (such as PMS consumption, catalyst consistence and initial pH value), different reaction system and catalyst repeatability on ODA degradation were also explored. And by identification of main radical experiment, SO₄^— and HO were both confirmed the primary radicals. What's more, extra anion and nature organic matter (NOM) addition experiment displayed that NOM, NO₃^— and CO₃^2— perform a negative effect on ODA degradation but Cl^— could promote it. In addition, repeated experiments and metal leaching after degradation showed good stability of Fe-Mn-LDH. Finally, based on the XPS and Gas Chromatography-Mass Spectrometer (GS-MS) technology, the possible degradation mechanism and pathway were proposed.
图文摘要: