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24641. 题目: Use of soil enzyme activities to assess the recovery of soil functions in abandoned coppice forest systems
文章编号: N19080606
期刊: Science of The Total Environment
作者: Hanadi Ananbeh, Marko Stojanović, Antonio Pompeiano, Stanislava Voběrková, Carmen Trasar-Cepeda
更新时间: 2019-08-06
摘要: Coppicing consists of periodically cutting back tree stems to ground level to stimulate the growth of multiple stems from the stool. In Central Europe, many coppiced forests were abandoned at the beginning of the last century owing to a decline in the demand for charcoal and wood. This was assumed to enable the forests to recover and the properties to become similar to those of unmanaged forest (high forest). Most studies on abandoned coppiced forest have focused on forest recovery, while soil recovery has generally been overlooked. With the aim of filling this gap, this study investigated the effect of coppicing abandonment on soil recovery by analysing the changes in soil enzyme activities (dehydrogenase, β-glucosidase, invertase, urease, acid phosphatase and arylsulphatase). Two differently managed sessile oak (Quercus petraea) forests were selected for study: a former coppice forest, abandoned >90 years ago, and an undisturbed forest. The analytical data were compared to assess the degree of recovery of the soil in the abandoned coppice forest. The soil organic matter content was two times lower in the abandoned coppice than in the high forest, suggesting that organic matter depletion due the past coppicing is a long-term effect. All of the absolute enzyme activities were also two times lower in the abandoned coppice forest soil than in the high forest soil. However, the specific enzyme activities were similar in both types of soil. This indicates that metabolic activity is similar in both soil types, suggesting that it either recovers faster than organic matter and soil enzyme activity or that, despite the depletion in organic matter and enzyme activities, metabolic activity was sustained in coppiced forest soil. However, in the latter case this would imply that organic matter and soil enzymes were lost in exactly the same proportion, which is highly improbable.
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24642. 题目: Effect of neap-spring hydrodynamics on salt and suspended sediment transport in multi-branched urban estuaries
文章编号: N19080605
期刊: Science of The Total Environment
作者: Joan Cecilia Casila, Victor Ella, Katsuhide Yokoyama
更新时间: 2019-08-06
摘要: Unique neap and spring tide hydrodynamic features were studied in the estuarine areas of multi-branched urban rivers in Tokyo, Japan. Intensive measurements of salinity, turbidity, dissolved oxygen, velocity, particulate organic matter (POM), and nutrients were conducted for 13 h in five stations simultaneously on July 3 and July 11, 2017. Water sampling, analysis and calculations of salt and sediment transport were performed. Results showed that the Arakawa and Sumida Rivers follow the typical natural estuary hydrodynamics while Shakujii River followed a typical artificial urban estuary. Shakujii River upstream estuary had lower flow velocity during spring tide (−0.05 to 0.04 m/s) than neap tide (−0.09 to 0.16 m/s) because of the channel slope that does not allow the transit of water to upstream even during high tide. Shakujii River downstream estuary had hypoxic (DO < 2 mg/L) bottom depths during neap and spring tide. Sumida River and Shakujii River are adjacent yet the nutrient and POM had different nature. Shakujii River is highly influenced by freshwater from combined sewer systems carrying POM, nutrients and sediments. The freshwater was 54% (14,650 m³) and 100% (28,671.1 m³) by volume during neap and spring tide, respectively. The POM and nutrients in Sumida River is influenced by tidal processes and tributary rivers. SS was transported from Sumida to Shakujii River during flood phase of spring tide. Freshwater from Arakawa River flows to Sumida River during ebb tide. Salt (−0.066 kg/m/s) and SS (−0.16 to −2.435 kg/m/s) were retained in the estuaries which may lead to river deterioration and occurrence of scum, hypoxia and odor. The results of the study, particularly on Shakujii River, are significant and could serve as basis for water quality management in similar urban estuaries.
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24643. 题目: Aerobic denitrification performance of strain Acinetobacter johnsonii WGX-9 using different natural organic matter as carbon source: Effect of molecular weight
文章编号: N19080604
期刊: Water Research
作者: Gang Wen, Tong Wang, Kai Li, Hanyue Wang, Jingyi Wang, Tinglin Huang
更新时间: 2019-08-06
摘要: The aim of this study was to investigate the effect of natural organic matter (NOM) including humic acid (HA) and fulvic acid (FA), intracellular organic matter (IOM) extracted from Microcystis aeruginosa (MA) and Chlorella sp. (CH), and their different molecular weight (MW) fractions on the aerobic denitrification performance of bacterial strain WGX-9 by monitoring nitrogen removal efficiency and testing changes in organic matter with HA, FA, MA-IOM and CH-IOM as the sole carbon source. Strain WGX-9 was identified as Acinetobacter johnsonii and exhibited excellent aerobic denitrification capability. The nitrate removal efficiency with IOM as the sole carbon source was relatively higher than that with NOM as the sole carbon source. The prepared NOM and extracted IOM samples were separated into six fractions with MW cut-offs of 100, 30, 10, 5 and 1 kDa. The fraction of MW > 100 kDa contributed the largest amount to the MW distribution, accounting for 77.11%, 29.00%, 44.97% and 24.81% of HA, FA, MA-IOM, and CH-IOM, respectively. Nitrate removal efficiency was improved with decreasing MW of organic matter. For example, nitrate removal efficiency was 26.50%, 32.41%, 27.88% and 43.89% using HA, FA, MA-IOM, and CH-IOM fractions of MW > 100 kDa as the carbon source, whereas with MW < 1 kDa, it increased to 36.67%, 37.88%, 60.90%, and 68.90%, respectively. This is probably because the smaller MW fraction is more suitable for bacterial growth. These results demonstrate that the strain WGX-9 can utilize lower MW organic matter, which lays the foundations for nitrogen removal in actual drinking water reservoirs.
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24644. 题目: Pore-scale lattice Boltzmann modeling of solute transport in saturated biochar amended soil aggregates
文章编号: N19080603
期刊: Journal of Hydrology
作者: Hongxiang Zhou, Xiuling Yu, Cheng Chen, Shenggao Lu, Laosheng Wu, Lingzao Zeng
更新时间: 2019-08-06
摘要: Biochar has been increasingly used as an amendment to enhance soil structure and improve soil hydraulic properties. Nevertheless, there are very limited physically based studies to investigate solute transport in biochar-amended soils at pore scale. In this study, for the first time, synchrotron-based X-ray micro-computed tomography (SR-μCT) was used to obtain high-resolution pore geometries of two clayey soils and their biochar amended samples, then the three-dimensional lattice Boltzmann (LB) method was implemented to simulate solute transport using the pore structure information. By using the innovative method of combining SR-μCT and LB simulation, we found that biochar amendment reduced the spatial variability of pore water velocity and increased the dispersion coefficient by one order of magnitude. In addition, we observed that anomalous dispersion was more likely to occur in soils with biochar amendment. Furthermore, soils after biochar amendment had relatively higher thresholds of both the transition zone and advection-dominated zone for the dispersion coefficients. These results are crucial in understanding nutrient transport processes and contaminant migration occurring at pore scale.

24645. 题目: Isotopic evidence for seasonal and long-term C and N cycling in a subtropical basin of southern China
文章编号: N19080602
期刊: Journal of Hydrology
作者: Yingxue Xuan, Changyuan Tang, Yingjie Cao, Rui Li, Tao Jiang
更新时间: 2019-08-06
摘要: Knowledge about the origin and transformation of nutrients at different temporal scales in river ecosystems can provide a better understanding of carbon (C) and nitrogen (N) cycles in rivers and bear important implications for regional and global C and N cycling. In this study, stable isotopes of C and N (δ¹³C and δ¹⁵N) and a radioactive isotope of ²¹⁰Pb were used to investigate the factors affecting seasonal and long-term changes in N source apportionment and C and N biogeochemical processes in the Beijiang River located in the Pearl River basin, China. Source apportionment by a Bayesian model (stable isotopic analysis in R, SIAR) showed significant seasonal variations. During the flood season, the dominant origins were non-point sources, such as soil N for dissolved nitrogen (DN, accounting for 38%), soil organic matter for particulate organic matter (POM, 58%) and sedimentary organic matter (SOM, 31%), due to intense precipitation. During the non-flood season, fertilizer became the dominant nitrate source (48%), and effluent detritus prevailed in the POM (47%) and SOM (32%) pools. N transformation between the DN, POM and SOM was influenced by seasonally variable hydrology. Our data suggested that low discharge was more favorable for the vertical mixing of the water column and sedimentation, which was supported by similar δ¹⁵N values in the DN, POM and SOM in the non-flood season. A sedimentary history record of 65 years (1951–2015) showed that the variation of N in the sediment was mainly affected by human activities. From 1999 to 2005, a decreasing trend in the δ¹⁵N values was observed due to the promotion of aquatic plant cultivation after reservoir impoundment. From 2005 to 2011, the enrichment in the δ¹⁵N values was caused by increases in manure and sewage due to the development of the tourism industry. From 2011 to 2015, the increase in pollution treatment funds from the government improved the water environment, resulting in δ¹⁵N depletion in the sediment. At the 65-year temporal scale, increased temperature and CO₂ concentration had less impact on the C and N cycles in river ecosystems, however, high discharge could increase the C and N contents, and flood events might increase the δ¹⁵N values in the sediment. This study provided more detailed information regarding the nutrient sources and improved our understanding of the C and N cycling processes at different temporal scales in river ecosystems.
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24646. 题目: Geochemical, mineralogical and statistical characteristics of arsenic in groundwater of the Lanyang Plain, Taiwan
文章编号: N19080601
期刊: Journal of Hydrology
作者: Chen-Wuing Liu, Ming-Zhe Wu
更新时间: 2019-08-06
摘要: High arsenic concentrations (average 0.1 mg/L) of groundwater were found in Lanyang plain of Taiwan. In this study, 39 groundwater samples from 23 wells were collected and 14 hydro-geochemical parameters were analyzed. Factor analysis was applied to determine major influence factors of the arsenic enriched groundwater quality, and PHREEQC was used to calculate the distribution of aqueous species and saturation index of which affected the hydrogeochemistry of groundwater. 393 geological core samples from 9 drilling wells were collected and analyzed the contents of total arsenic and iron. Moreover, core samples associated with high arsenic concentration groundwater were selected, mineralogical phases were analyzed using X-ray fluorescence (XRF), high resolution X-ray photoelectron (XPS) and scanning electron microscope and energy dispersive spectrometer (SEM-EDS). Results of the arsenic enrichment factor determined by factor analysis indicated that infiltration of the organic and nitrogen pollutants from anthropogenic activities to shallow groundwater, and the reductive dissolution from iron oxyhydroxides in the deep aquifer were the main processes of arsenic release to groundwater from the sediment. Total arsenic and iron contents of the core samples were well correlated in marine sequences. The presence of clay layer within the subsurface may increase in the As contamination in groundwater aquifer. However the time for As release from clay layer to lower aquifer may require tens or hundreds years to complete under natural environment condition. Surface analyses of core sample performed by XPS showed that arsenic was adsorbed or co-precipitated with non-crystalline iron oxyhdroxides and sulfides. After a long term burial of sediment, microbial metabolism of organic matter creates a more reducing environment, arsenic may then be gradually released from iron oxyhydroxides by reductive dissolution or desorption to aqueous phase. The framboidal-diagenetic type phase was identified by XPS and the groundwater is supersaturated with respect to pyrite and orpiment determined by PHREEQC are suggesting sulfide minerals co-precipitate As. Arsenic in sediments is released into groundwater primarily by the reductive dissolution of As-bearing Fe-oxyhydroxides in reducing environment in the Lanyang plain.

24647. 题目: The nutrient release rate accounts for the effect of organic matter type on soil microbial carbon use efficiency of a Pinus tabulaeformis forest in northern China
文章编号: N19080505
期刊: Journal of Soils and Sediments
作者: Zhiyong Zhou, Huan Zhang, Zhen Yuan, Runing Gong
更新时间: 2019-08-05
摘要: Purpose: Microbial carbon use efficiency (CUE) greatly controls the magnitude of soil organic carbon turnover. This study was conducted to estimate the CUE with the additions of different organic matter (OM) to the top soil of a Pinus tabulaeformis forest and explore the variations of CUE and ecoenzyme activity with the quality of the added OM. Materials and methods: Five types of OM, i.e., P. tabulaeformis leaves, Quercus wutaishanica leaves, maize straw, biochar, and wood, were separately crushed by a machine and then manually mixed in the top 20 cm of soil in a plot at 5 × 5 m in June 2014. Concurrently, 20 g of each OM larger than 1 cm was put in a nylon bag of 10 × 15 cm and placed above the plot ground to monitor the OM decomposition. The soil samples were taken and analyzed for the physicochemical properties, the extracellular enzyme activity, and soil microbial biomass, and the OM decomposition rate was also measured in August 2017. Results and discussion: The OM in the litter bag absorbed nitrogen from the soil particle during the decomposition period, and the nitrogen release rates of wood debris and maize straw were significantly lower at − 625.01% and − 276.98%. The carbon targeting enzyme, i.e., α-1,4-glucosidase (AG), was also influenced by the OM addition and changed from 5.39 nmol h⁻¹ g⁻¹ with the Q. wutaishanica leaf addition to 14.82 nmol h⁻¹ g⁻¹ with the wood debris addition. Significant differences were simultaneously detected in the soil microbial biomass carbon content among different OM additions. These changes in soil biophysical properties contributed to much of the variation in CUE_C:N. The CUE_C:N meaning the microbial carbon assimilation at the cost of nitrogen was highest at 0.221 for wood debris addition. Conclusions: The addition of OM differing in quality could influence the soil resource content, exo-enzyme activity, and soil microbial biomass through its nutrient release rate. The CUE_C:N could act as an integrative proxy of soil biophysical properties because it also correlated with the soil nutrient content, ecoenzymatic stoichiometry and the OM nutrient release rate. The high CUE_C:N value indicated a big carbon stabilization in soils with wood debris addition.

24648. 题目: Processes controlling arsenic enrichment along the eastern Arabian Sea surficial sediments
文章编号: N19080504
期刊: Environmental Earth Sciences
作者: Prakash Babu Chakka
更新时间: 2019-08-05
摘要: The processes enriching redox-sensitive arsenic (As) was investigated in 111 surficial sediments (27–3679 m water depth) overlain by varying levels of dissolved oxygen along the eastern Arabian Sea. Under oxygenated conditions, diagenetic enrichment of As was noticed at deeper water depths (> 1200 m), while lattice held As dominant at few station from shallow depths (< 150 m). In sediments impinged by oxygen minimum zone (OMZ; 150–1200 m), As is released from organic matter during sub-oxic diagenesis. As seems to precipitate as As/iron sulfide mineral under intense OMZ based on a positive correlation between As and S and Cd in northeastern part of the study area, while As may diffuse to water column under less intense OMZ evidenced by lack of correlation between As and S and Cd in southeastern part. Several processes can enrich As. A careful approach is recommended for its usage in understanding anthropogenic sources, transport, and paleodepositional environment along eastern Arabian Sea.

24649. 题目: Efficacy of spent tea waste as chemically impregnated adsorbent involving ortho-phosphoric and sulphuric acid for abatement of aqueous phenol—isotherm, kinetics and artificial neural network modelling
文章编号: N19080503
期刊: Environmental Science and Pollution Research
作者: Uttarini Pathak, Aastha Jhunjhunwala, Ananya Roy, Papita Das, Tarkeshwar Kumar, Tamal Mandal
更新时间: 2019-08-05
摘要: The current study emphasises on sorptive expulsion of phenol from aqueous solution using ortho-phosphoric acid (STAC-O) and sulphuric acid (STAC-H)-activated biochar derived from spent tea waste. STAC-O and STAC-H were instrumentally anatomised using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), BET surface area and thermal gravimetric analyser. Equilibrium and kinetic data were implemented for the investigative parametric batch study to prospect the influence of adsorbent dosage, contact time, initial concentration and pH for eradication of phenol from aqueous solution. The maximum phenolic removals by STAC-O and STAC-H are 93.59% and 91.024% respectively at the parametric conditions of adsorbent dosage 3 g/l time 2 h, initial phenol concentration 100 mg/l and pH 8. Non-linear regression of adsorption isotherms and kinetics was accomplished using the equilibrium data. Both the specimens were compared, and it delineated that Temkin isotherm model is contented. The maximum adsorption intakes for STAC-H and STAC-O were 185.002 mg/g and 154.39 mg/g respectively. Pseudo-second-order kinetic model was best fitted for portraying the chemisorption phenomena. Boyd kinetic and intra-particle diffusion model were investigated to elucidate the diffusion mechanism involved in the process. Desorption study was employed for determining the regeneration proficiency of the adsorbents using water, ethanol and NaOH with maximum 93% and 51.16% extrusion for STAC-O and STAC-H respectively. The process parameters involved in this study were further analysed using artificial neural network perusal to determine the input–output relationships and data pattern. The overall adsorption study along with cost estimation exhibited that bidirectional activation of spent tea biochar was prospective in abatement of phenol from aqueous media.

24650. 题目: The non-conservative distribution pattern of organic matter in Rajang, a tropical river with peatland in its estuary
文章编号: N19080502
期刊: Biogeosciences
作者: Zhuoyi Zhu, Joanne Oakes, Bradley Eyre, Youyou Hao, Edwin Sien Aun Sia, Shan Jiang, Moritz Müller, and Jing Zhang
更新时间: 2019-08-05
摘要: South-east Asian peatland-draining rivers have attracted much attention due to their high dissolved organic carbon (DOC) yield and high CO₂ emissions under anthropogenic activities. In August 2016, we carried out a field investigation of the Rajang river and estuary, a tropical system located in Sarawak, Malaysia. The Rajang has peatland in its estuary while the river basin is covered by tropical rainforest. DOC δ¹³C in the Rajang ranged from −28.7 ‰ to −20.1 ‰ and a U-shaped trend from river to estuary was identified. For particulate organic carbon (POC), the δ¹³C ranged between −29.4 ‰ to −31.1 ‰ in the river and a clear increasing trend towards more δ¹³C -enriched with higher salinity existed in the estuary. In the estuary, there was a linear conservative dilution pattern for dissolved organic matter composition (as quantified by D/L amino acids enantiomers) plotted against DOC δ¹³C, whereas when plotted against salinity dissolved D/L amino acids enantiomers values were higher than the theoretical dilution value. Together, these data indicate that the addition of DOC in estuary (by peatland) not only increased the DOC concentration, but also altered its composition, by adding more bio-degraded, ¹³C-depleted organic matter into the bulk dissolved organic matter. Alteration of organic matter composition (adding of more degraded subpart) was also apparent for the particulate phase, but patterns were less clear. The Rajang was characterized by DOC / DON ratios of 50 in the river section, with loss of DON in the estuary increased the ratio to 140, suggesting the unbalanced export pattern for organic carbon and nitrogen, respectively. Under anthropogenic activities, further assessment of organic carbon to nitrogen ratio is needed.

24651. 题目: Molecular Insights into the Formation and Remobilization Potential of Nonextractable Anthropogenic Organohalogens in Heterogeneous Environmental Matrices
文章编号: N19080501
期刊: Journal of Hazardous Materials
作者: Xiaojing Zhu, Larissa Dsikowitzky, Mathias Ricking, Jan Schwarzbauer
更新时间: 2019-08-05
摘要: Anthropogenic organohalogens (AOHs) are toxic and persistent pollutants that occur ubiquitously in the environment. An unneglectable portion of them can convert into nonextractable residues (NER) in the natural solid substances. NER-AOHs are not detectable by conventional solvent-extraction, and will get remobilized through changes of surrounding environment. Consequently, the formation and fate of NER-AOHs should be investigated comprehensively. In this study, solvent extraction, sequential chemical degradation and thermochemolysis were applied on different sample matrices (sediments, soils and groundwater sludge, collected from industrial areas) to release extractable and nonextractable AOHs. Covalent linkages were observed most favorable for the hydrophilic-group-containing monocyclic aromatic AOHs (HiMcAr-AOHs) (e.g. halogenated phenols, benzoic acids and anilines) incorporating into the natural organic matter (NOM) as NER. Physical entrapment mainly contributed to the NER formation of hydrophobic monocyclic aromatic AOHs (HoMcAr-AOHs) and polycyclic aromatic AOHs (PcAr-AOHs). The hypothesized remobilization potential of these NER-AOHs follow the order HiMcAr-AOHs > HoMcAr-AOHs/ aliphatic AOHs > PcAr-AOHs. In addition, the NOM macromolecular structures of the studied samples were analyzed. Based on the derived results, a conceptual model of the formation mechanisms of NER-AOHs is proposed. This model provides basic molecular insights that are of high value for risk assessment and remediation of AOHs.
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24652. 题目: Choosing sampling methods for Chilopoda, Diplopoda and Isopoda (Oniscidea): A case study for ferruginous landscapes in Brazilian Amazonia
文章编号: N19080406
期刊: Applied Soil Ecology
作者: Marcus Paulo Alves de Oliveira, Rafaela Bastos-Pereira, Silvia Helena Soares Torres, Thaís Silveira Pereira, Fagner Márcio Batista, João Paulo Alves, Luiz Felipe Moretti Iniesta, Rodrigo Salvador Bouzan, Amazonas Chagas-Jr, Xavier Prous, Thadeu Pietrobon, Rodrigo Lopes Ferreira
更新时间: 2019-08-04
摘要: The edaphic fauna plays an important role in the organic matter dynamics of the soil. Millipeds (Diplopoda), centipeds (Chilopoda) and isopods (Isopoda) are among the main components of the soil fauna. Vegetation structure represents one of the main factors influencing composition and diversity of these species that inhabit leaf litter and soil, what is particularly important in the Amazon Forest, where there are several singular vegetation types. Savannah and forest areas stand out in ferruginous hills, which represents one of the most poorly known and highly threatened ecosystems in the Amazon. However, sampling the edaphic fauna in high diversity sites represents a challenging task. Studies have shown that sampling method may influence observed patterns of diversity. From this perspective, the present study aimed to (i) investigate whether assemblages of Chilopoda, Diplopoda and Isopoda differ between vegetation types in the Amazon, (ii) indicate how biological parameters behave in such communities, (iii) identify which method or combination of methods is better suited to sample species richness and (iv) quantify the efficiency of each method regarding time of work and cost. Sampling was conducted by means of hand collection, leaf litter collection, hay-bait traps and soil sampling in four patches, two in the savannah (also called canga) and two in the forest. Richness was higher in forest habitats for Chilopoda and Diplopoda, while for Isopoda there was no significant difference. Species composition also differed between vegetation types for Chilopoda and Isopoda, but not for Diplopoda. Beta diversity between vegetation types was mainly determined by nestedness and balancing, while turnover was the main beta diversity component responsible for differences among methods. Soil sampling and hand collection added more species to the samples, therefore, this combination was the most efficient to access diversity. Our results support the hypothesis that differences in the soil cover promoted by distinct vegetation types influence the species diversity and composition of edaphic fauna. The differences were mainly determined by nestedness and balancing, indicating that the fauna sampled in the canga represents a subset of those present in the surrounding forest. In this sense, even in ecosystems with distinct vegetation types, the combination of soil and surface sampling methods is recommended. Lastly, the present study proposes a set of decision rules and a key to select the most appropriate method to sample the studied taxonomic groups.

24653. 题目: Cu(II) adsorption on 2-thiouracil-modified Luffa Cylindrica biochar fibres from artificial and real samples, and competition reactions with U(VI)
文章编号: N19080405
期刊: Journal of Hazardous Materials
作者: Ioanna Liatsou, Ioannis Pashalidis, Carsten Dosche
更新时间: 2019-08-04
摘要: The adsorption of Cu(II) ions by biochar fibres prior and after modification with 2-thiouracil on real and artificial samples has been studied by batch-type adsorption experiments, FTIR and XPS spectroscopy and competition reactions using U(VI) ions as competitor cations. The experimental data of the artificial samples clearly show that the modified material presents extraordinary higher affinity for Cu(II) ions even in the acidic pH range, the spectroscopic data indicate the formation of inner-sphere complexes and the competition reactions significantly higher selectivity of the 2-thiouracil modified biochar fibres for Cu(II). The 2-thiouracil-modified biochar fibres have been successfully applied to acid mine drainage (AMD) samples regarding the selective separation of Cu(II) ions from “real” samples. Regarding the desorption of copper from the biochar surface, although 100% copper recovery was achieved by eluting the metal ion using 1 M HNO3, the deterioration of the modified biochar fibers due to extensive 2-thiouracil release from the biochar surface limits the applicability of the present adsorbent in routine and large-scale applications.
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24654. 题目: Cellulose derived carbon nanofiber: A promising biochar support to enhance the catalytic performance of CoFe₂O₄ in activating peroxymonosulfate for recycled dimethyl phthalate degradation
文章编号: N19080404
期刊: Science of The Total Environment
作者: Lu Gan, Qiang Zhong, Aobo Geng, Linjie Wang, Chi Song, Shuguang Han, Juqing Cui, Lijie Xu
更新时间: 2019-08-04
摘要: We prepared carbon nanofiber (CCNF) using cellulose as the carbon source in this study and utilized for the first time as the support to enhance the catalytic performance of the cobalt ferrite (CoFe₂O₄) for peroxymonosulfate (PMS) activation. The catalytic capability of the CoFe₂O₄/CCNF nanocomposites activated PMS was investigated through degrading dimethyl phthalate (DMP), a classical organic pesticide pollutant, in water media. The influence factors like CCNF content, nanocomposite and PMS dosage, DMP content, and pH value on the degradation speed were systematically investigated and analyzed. Since CoFe₂O₄ is a spinel structured molecule which is magnetically separable, the reusability of the prepared CoFe₂O₄/CCNF nanocomposites under multiple cycles was also tested. Besides, the degradation intermediates during the catalytic process were also analyzed and identified by liquid chromatography-mass spectrometry (LC-MS) with a possible degradation mechanism. The results indicated that the prepared nanocomposite had promising catalytic capability in degrading DMP, in which the SO₄⁻ radicals played the main role as the active oxidation agent. Furthermore, the CoFe₂O₄/CCNF nanocomposites exhibited very good stability and reusability. The present study provides a clean biochar supported catalyst which could readily enhance the PMS activation efficiency for recycled decontamination of refractory organic pollutants in water media.
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24655. 题目: Enhanced nitrobenzene reduction by modified biochar supported sulfidated nano zerovalent iron: Comparison of surface modification methods
文章编号: N19080403
期刊: Science of The Total Environment
作者: Dejin Zhang, Yang Li, Aiwu Sun, Siqi Tong, Guanyong Su, Xinbai Jiang, Jiansheng Li, Weiqing Han, Xiuyun Sun, Lianjun Wang, Jinyou Shen
更新时间: 2019-08-04
摘要: In our previous study, biochar (BC) supported sulfidated nano zerovalent iron (S-nZVI@BC) was prepared for nitrobenzene (NB) reduction. In this study, in order to further improve the reduction performance of S-nZVI@BC, BC was modified before the loading of S-nZVI through three methods: oxidant (H₂O₂) pretreatment, alkali (NaOH) pretreatment and acid (HCl) pretreatment. The results indicated that S-nZVI could be evenly distributed onto HCl-BC due to increased surface area, negative surface charge and increased acidic functional groups on HCl-BC. At an initial concentration of 200 mg L⁻¹, NB could be completely removed by S-nZVI@HCl-BC within a reaction time as short as 60 min, indicating rather excellent performance of S-nZVI@HCl-BC. NB reduction performance followed the order: S-nZVI@HCl-BC > S-nZVI@NaOH-BC > S-nZVI@BC > S-nZVI@H₂O₂-BC. The mass ratio of S-nZVI and HCl-BC was optimized in terms of NB removal efficiency, with 3:1 being identified as the best mass ratio. Furthermore, the mechanism involved in the enhanced NB reduction by S-nZVI@HCl-BC was proposed. This study demonstrated that S-nZVI@HCl-BC is a promising alternative for efficient NB removal from wastewater.
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24656. 题目: Comparison of coagulative colloidal microbubbles with monomeric and polymeric inorganic coagulants for tertiary treatment of distillery wastewater
文章编号: N19080402
期刊: Science of The Total Environment
作者: Ming Zhang, Zhongxia Cai, Li Xie, Yin Zhang, Linfeng Tang, Qi Zhou, Zhimin Qiang, Hua Zhang, Daoyong Zhang, Xiangliang Pan
更新时间: 2019-08-04
摘要: The flotation using coagulative colloidal gas aphrons (CCGAs) is of great potential in effectively removing the recalcitrant dissolved organic matter (DOM) and colorants from the bio-chemically treated cassava distillery wastewater. As bubble modifier, the monomeric and polymeric inorganic coagulants need to be studied considering their distinct influence on the surfactant/coagulant complex, the properties of colloidal aphrons as well as the process performance and mechanisms. Such studies help to create robust CCGAs with high flotation potential. In this work, the commonly-used monomeric and polymeric Al(III)- and Fe(III)-coagulants were combined with the cationic surfactant – cetyl trimethylammonium bromide (CTAB) to generate CCGAs. The CCGAs functionalized with Al(III)-coagulants (both monomeric and polymeric ones) were featured as small bubble size, strong stability and high air content. Particularly, the monomeric Al(III)-coagulant (AlCl₃ in this work) resulted in low surface tension and high foamability when being mixed with CTAB in the bubble generation solution. Those CCGAs achieved high removal efficiencies of DOM and colorants at low coagulant concentrations. The molecular weight of DOM in effluent was well controlled below 1 kDa by CCGAs. For the flocs obtained from CCGA-flotation, the characteristic Raman band of DOM and colorants showed the layer-by-layer variation of Raman intensity which decreased from the outer layer to the center. In contrast with the conventional coagulation-flotation, the reduction of coagulant dosage by CCGAs was 67% (AlCl₃), 25% (polyaluminum chloride), 60% (Fe₂(SO₄)₃) and 40% (polyferric sulfate). The sludge production could then be largely reduced, and meanwhile, the retention time was shortened by 9.5 min.
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24657. 题目: Solubilization and characterization of extracellular proteins from anammox granular sludge
文章编号: N19080401
期刊: Water Research
作者: Marissa Boleij, Thomas Seviour, Lan Li Wong, Mark C.M. van Loosdrecht, Yuemei Lin
更新时间: 2019-08-04
摘要: Elucidating the extracellular polymeric substances (EPS) of anammox granular sludge is important for stable nitrogen removal processes in wastewater treatment. However, due to a lack of standardized methods for extraction and characterization, the composition of anammox granule EPS remains mostly unknown. In this study, alkaline (NaOH) and ionic liquid (IL) extractions were compared in terms of the proteins they extracted from different “Candidatus Brocadia” cultures. We aimed to identify structural proteins and evaluated to which extend these extraction methods bias the outcome of EPS characterization. Extraction was focussed on solubilization of the EPS matrix, and the NaOH and IL extraction recovered on average 20% and 26% of the VSS, respectively. Using two extraction methods targeting different intermolecular interactions increased the possibility of identifying structural extracellular proteins. Of the extracted proteins, ∼40% were common between the extraction methods. The high number of common abundant proteins between the extraction methods, illustrated how extraction biases can be reduced when solubility of the granular sludge is enhanced. Physicochemical analyses of the granules indicated that extracellular structural matrix proteins likely have β-sheet dominated secondary structures. These β-sheet structures were measured in EPS extracted with both methods. The high number of uncharacterized and possible moonlighting proteins confounded identifying structural (i.e. β-sheet dominant) proteins. Nonetheless, new candidates for structural matrix proteins are described. Further current bottlenecks in assigning specific proteins to key extracellular functions in anammox granular sludge are discussed.
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24658. 题目: Survey of bioaccessible pyrethroid insecticides and sediment toxicity in urban streams of the northeast United States
文章编号: N19080309
期刊: Environmental Pollution
作者: Kara E. Huff Hartz, Samuel A. Nutile, Courtney Y. Fung, Federico L. Sinche, Patrick W. Moran, Peter C. Van Metre, Lisa H. Nowell, Michael J. Lydy
更新时间: 2019-08-03
摘要: Pyrethroids are a class of widely-used insecticides that can be transported from terrestrial applications to aquatic systems via runoff and tend to sorb to organic carbon in sediments. Pyrethroid occurrence is detrimental to stream ecosystems due to toxicity to sediment-dwelling invertebrates which are particularly at risk of pyrethroid exposure in urban streams. In this work, 49 streams located in watersheds in the northeastern United States were surveyed for nine current-use pyrethroids using two extraction methods. Total sediment concentrations were determined by exhaustive chemical extraction, while bioaccessible concentrations were determined by single-point Tenax extraction. Total and bioaccessible pyrethroid concentrations were detected in 76% and 67% of the sites, and the average sum of pyrethroids was 232 ng/g organic carbon (OC) for total and 43.8 ng/g OC for bioaccessible pyrethroids. Bifenthrin was the most commonly detected pyrethroid in streambed sediments. Sediment toxicity was assessed using 10-d Hyalella azteca bioassays, and 28% and 15% of sediments caused a decrease in H. azteca biomass and survival, respectively. A temperature-based focused toxicity identification evaluation was used to assess pyrethroids as the causal factor for toxicity. The concentrations of pyrethroids was only weakly correlated with the degree of urban land use. Sediment toxicity was predicted by total and bioaccessible pyrethroid concentrations expressed as toxic units. This work suggests that bioaccessibility-based methods, such as Tenax extraction, can be a valuable tool in assessing sediment toxicity.
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24659. 题目: Predictive role of spectral slope ratio towards 17α-ethynylestradiol photodegradation sensitized by humic acids
文章编号: N19080308
期刊: Environmental Pollution
作者: Dong Ren, Zhaogang Ren, Fang Chen, Bin Wang, Bin Huang
更新时间: 2019-08-03
摘要: Humic acids (HAs) have been shown to dominate the photodegradation of steroid estrogens in natural waters. Nevertheless, how the photosensitizing ability of HAs relates to their structural and optical characteristics remains largely unknown. In this study, 17α-ethynylestradiol (EE2) was selected as a model compound to study to what extent easily-measurable characteristics of HAs might be used to predict their photosensitization potency. HAs were extracted from sediments of two different sources, and then subjected to structural and optical properties characterization using elemental analyzer, UV–vis spectroscopy and fluorescence spectroscopy. Photochemical experiments show that the HAs from the two sources can effectively meditate EE2 photodegradation. Although with drastically different structural and optical properties, the photosensitizing ability of these HAs towards EE2 can be well described by simple linear regressions using a spectroscopic index, the spectral slope ratio (S_R). This optical indicator is correlated with various physicochemical properties of HAs, including the molecular weight, lignin content, charge-transfer interaction potential, photobleaching extent and sources. No universal prediction model could be established for predicting EE2 photodegradation kinetics on the basis of S_R, but in specific waters S_R could be a powerful indictor for predicting the EE2 photodegradation sensitized by HAs.
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24660. 题目: Mechanisms of carbon sequestration and stabilization by restoration of arable soils after abandonment: A chronosequence study on Phaeozems and Chernozems
文章编号: N19080307
期刊: Geoderma
作者: Irina Kurganova, Agustin Merino, Valentin Lopes de Gerenyu, Nieves Barros, Olga Kalinina, Luise Giani, Yakov Kuzyakov
更新时间: 2019-08-03
摘要: Abandonment of croplands ongoing on 220 million ha worldwide contributes strongly to soil restoration by improvement of degraded properties and medium- and long-term carbon (C) sequestration in post-agricultural ecosystems. Two interrelated processes – decomposition and stabilization of soil organic carbon (SOC) – govern SOC dynamics and affect the C source or sink functions of former croplands. We investigated how the abandonment of arable soils affects (i) accumulation of SOC, its composition, stability, and turnover during the post-agricultural restoration of soils, and (ii) microbial activity parameters. A chronosequence study was carried in two bioclimatic zones of European Russia: deciduous forest (Luvic Phaeozems, PH-chronosequence) and dry steppe (Calcic Chernozems, CH-chronosequence). Each chronosequence included an arable soil, 3–4 soils abandoned at increasing time periods (up to 35 years), and natural soil: never cropped Phaeozem and completely restored Chernozem. We combined the results of nuclear magnetic resonance (NMR), thermal analysis including Differential Scanning Calorimetry and Derivative Thermogravimetry, long-term incubation for SOC mineralization, and microbiological activity (basal respiration and microbial C content). Degraded Phaeozems with low SOC amount had much higher relative increase in SOC content (134%) during the post-agricultural restoration compared to SOC-rich Chernozems (38%). SOC gains were recorded in all organic compound classes identified by NMR and thermal analysis, but the increase of recalcitrant SOC was more pronounced in the post-agricultural Chernozems than in the Phaeozems. The post-agricultural Chernozems were characterized by higher SOC aliphaticity and aromaticity than Phaeozems. Microbial activity and biodegradable SOC increased gradually during post-agricultural restoration. Being mostly a function of climate and vegetation, the soil type was the primary factor explaining the greatest portion (54–88%) of the total variance for most soil and microbial parameters. Concluding, despite SOC content increased in both Chernozems and Phaeozems during the post-agricultural restoration, the mechanisms of C sequestration and stabilization were dependent on climate, vegetation, and on the degradation intensity during the agricultural use. The accumulation of organic compounds was specific for virgin soils dominating in deciduous forest and steppes, and had direct consequences for microbial activities, C turnover and sequestration.
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