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22501. 题目: Mechanical pretreatment for increased biogas production from lignocellulosic biomass; predicting the methane yield from structural plant components
文章编号: N18071105
期刊: Waste Management
作者: Panagiotis Tsapekos, Panagiotis G. Kougias, Irini Angelidaki
更新时间: 2018-07-11
摘要: Lignocellulosic substrates are associated with limited biodegradability due to the structural complexity. For that reason, a pretreatment step is mandatory for efficient biomass transformation which will lead to increased bioenergy output. The aim of the present study was to assess the efficiency of two pretreatment machines to enhance the methane yield of meadow grass. Specifically, the application of shearing forces with a rotated plastic sweeping brush against a steel roller significantly increased biomass biodegradability by 20% under relatively gentle operation conditions (600 rpm). The more intense operation (1200 rpm) was not associated with higher methane yield enhancement. Regarding an alternative machine, in which the brush was replaced with a coarse steel roller resulted in a more distinct effect (+27%) despite the lower rotating speed ( 400 rpm). Moreover, the association of the substrate’s individual chemical components and the practical methane yield was assessed, establishing single and multiple linear regression models. However, the estimation accuracy was rather low with either single (regressor: lignin, R2: 0.50) or multiple linear regression analyses (regressors: arabinan-lignin-protein, R2: 0.61). Results showed that poorly lignified plant tissue containing relatively high fractions of protein and arabinan is more susceptible to anaerobic digestion.

22502. 题目: Effect of humic acid & bacterial exudates on sorption–desorption interactions of 90Sr with brucite
文章编号: N18071104
期刊: Environ. Sci.: Processes Impacts
作者: Hollie Ashworth, Liam Abrahamsen-Mills, Nick Bryan, Lynn Foster, Jonathan R. Lloyd, Simon Kellet, Sarah Heath
更新时间: 2018-07-11
摘要: One of the nuclear fuel storage ponds at Sellafield (United Kingdom) is open to the air, and has contained a significant inventory of corroded magnox fuel and sludge for several decades. As a result, some fission products have also been released into solution. 90Sr is known to constitute a small mass of the radionuclides present in the pond, but due to its solubility and activity, it is at risk of challenging effluent discharge limits. The sludge is predominantly composed of brucite (Mg(OH)2), and organic molecules are known to be present in the pond liquor with occasional algal blooms restricting visibility. Understanding the chemical interactions of these components is important to inform ongoing sludge retrievals and effluent management. Additionally, interactions of radionuclides with organics at high pH will be an important consideration for the evolution of cementitious backfilled disposal sites in the UK. Batch sorption–desorption experiments were performed with brucite, 90Sr and natural organic matter (NOM) (humic acid (HA) and Pseudanabaena catenata cyanobacterial growth supernatant) in both binary and ternary systems at high pH. Ionic strength, pH and order of addition of components were varied. 90Sr was shown not to interact strongly with the bulk brucite surface in binary systems under pH conditions relevant to the pond. HA in both binary and ternary systems demonstrated a strong affinity for the brucite surface. Ternary systems containing HA demonstrated enhanced sorption of 90Sr at pH 11.5 and vice versa, likely via formation of strontium–humate complexes regardless of the order of addition of components. The distribution coefficients show HA sorption to be reversible at all pH values studied, and it appeared to control 90Sr behaviour at pH 11.5. Ternary systems containing cyanobacterial supernatant demonstrated a difference in 90Sr behaviour when the culture had been subjected to irradiation in the first stages of its growth.

22503. 题目: Global challenges and adaptations in management practices to preserve soil carbon pool with changing climate
文章编号: N18071103
期刊: Environmental Earth Sciences
作者: Reshmi Sarkar
更新时间: 2018-07-11
摘要: Increasing CO2 levels and its consequent effects have been prominent with climate change. Three out of ten transgressed planetary boundaries reflect our planet’s status at tipping point. Soil Organic Carbon (SOC) which helps soil supply water and nutrients to plants through roots is inherently related to various ecological systems and needs urgent attention. Although the total SOC globally is more than the total carbon in biosphere and atmosphere, the vulnerability of SOC due to anthropogenic activities is unavoidable. The environmental factors affecting sequestration of SOC, soil fertility, crop production, accelerated SOC removal with rising temperatures, green-house gases emissions and climate change are interrelated. Thus, it is impossible to understand and estimate the various scenarios of impacts on SOC pool with ever-changing ecosystems and related processes in soil environment completely. Based on currently predicted climate change scenarios, if deforestation is controlled and reestablishment is achieved, tropical forests can trap atmospheric CO2 in the cheapest way and function as the largest sink on earth. The agricultural management practices (AMPs), which have been practiced in the last two decades and found helpful are suitable. However, some innovative adaptations such as crop modelling, selecting types of residue to change microbial communities, practices of grassland-grazing and low-C-emission AMPs are also necessary. To achieve the millennium development goals, we must accomplish food security, which relates all 17 sustainable development goals (SDGs) also relays agricultural systems, soil systems, ecosystem services, soil fertility and how best we nurture SOC pool with supportive AMPs.

22504. 题目: Bio-cord plays a similar role as submerged macrophytes in harboring bacterial assemblages in an eco-ditch
文章编号: N18071102
期刊: Environmental Science and Pollution Research
作者: Lei Zhou, Chengrong Bai, Jian Cai, Yang Hu, Keqiang Shao, Guang Gao, Erik Jeppesen, Xiangming Tang
更新时间: 2018-07-11
摘要: Artificial carriers are widely used to enhance the formation of biofilm and improve pollutants’ removal efficiency in agricultural wastewater treatment ditches (eco-ditches), yet comprehensive insight into their bacterial community is scarce. In this study, bacterial diversities in four different habitats—the water column, surface sediments, submerged macrophytes (Myriophyllum verticillatum L.), and the artificial carriers (bio-cord)—were compared in a Chinese eco-ditch. Comparable richness and evenness of bacterial communities were observed on M. verticillatum and bio-cord, both being higher than for free-living bacteria in the water column but lower than for bacteria in the surface sediment. The highest similarity of bacterial community composition and structure also occurred between M. verticillatum and the bio-cord, dominated by α- and γ-proteobacteria, Verrucomicrobia, and Bacteroidetes. Firmicutes and Planctomycetes, respectively, were the exclusive abundant phyla in M. verticillatum and the bio-cord, probably indicating the unique interaction between M. verticillatum and their epiphytic bacteria. Some abundant genera, such as Roseomonas, Pseudomonas, and Rhodopirellula, which were exclusively observed in M. verticillatum or the bio-cord, have been reported to have the same capacity to remove nitrogen and organic matter in wastewater treatment systems. In conclusion, in the studied eco-ditch, the bio-cord was found to play a similar role as submerged macrophytes in harboring bacterial assemblages, and we therefore propose that bio-cord may be a good alternative or supplement to enhance wastewater treatment in agricultural ditches.

22505. 题目: Production, characterization, and potential of activated biochar as adsorbent for phenolic compounds from leachates in a lumber industry site
文章编号: N18071101
期刊: Environmental Science and Pollution Research
作者: Flavia Lega Braghiroli, Hassine Bouafif, Nesrine Hamza, Carmen Mihaela Neculita, Ahmed Koubaa
更新时间: 2018-07-11
摘要: There is growing interest in low-cost, efficient materials for the removal of organic contaminants in municipal and industrial effluents. In this study, the efficiency of biochar and activated biochar, as promising adsorbents for phenol removal, was investigated at high (up to 1500 mg L-1) and low concentrations (0.54 mg L-1) in synthetic and real effluents (from wood-residue deposits in Québec), respectively. The performance of both materials was then evaluated in batch adsorption experiments, which were conducted using a low solid/liquid ratio (0.1 g:100 mL) at different phenol concentrations (C0 = 5–1500 mg L-1), and at 20 °C. Activated biochars presented higher phenol adsorption capacity compared to biochars due to their improved textural properties, higher micropore volume, and proportion of oxygenated carbonyl groups connected to their surface. The sorption equilibrium was reached within less than 4 h for all of materials, while the Langmuir model best described their sorption process. The maximum sorption capacity of activated biochars for phenol was found to be twofold relative to biochars (303 vs. 159 mg g-1). Results also showed that activated biochars were more effective than biochars in removing low phenol concentrations in real effluents. In addition, 95% of phenol removal was attained within 96 h (although 85% was removed after 4 h), thus reaching below the maximum authorized concentration allowed by Québec’s discharge criteria (0.05 mg L-1). These results show that activated biochars made from wood residues are promising potential adsorbent materials for the efficient treatment of phenol in synthetic and real effluents.

22506. 题目: Effects of pipe material on nitrogen transformation, microbial communities and functional genes in raw water transportation
文章编号: N18071018
期刊: Water Research
作者: Hang Xu, Chenshuo Lin, Wei Chen, Zhen Shen, Zhigang Liu, Taoyuan Chen, Yueting Wang, Yang Li, Chunhui Lu, Jian Luo
更新时间: 2018-07-10
摘要: Raw water transportation pipelines are vital in an urban water supply system for transporting raw water to drinking water treatment plants. This study investigated the effects of pipe material on nitrogen transformation, microbial communities and characteristics of related function genes in paint-lined steel pipe (PLSP) and cement-lined steel pipe (CLSP) raw water model systems. We established quantitative relationships between specific functional genes and change rates of nitrogen pollutants, which were verified by field investigation on nitrogen pollutant transformations in real raw water transportation systems. The results showed that the CLSP produced higher ammonia nitrogen (NH4+-N) transformation rates and higher effluent concentrations of nitrate nitrogen (NO3- -N) and dissolved organic nitrogen (DON) than the PLSP. Both pipes achieved high and stable nitrite nitrogen (NO2- -N) and low total nitrogen (TN) removal efficiency. Nitrification was found to be the dominant process in both model systems, especially in the CLSP. Characteristics of microbial communities and nitrogen functional genes, which were analysed by high-throughput pyrosequencing and quantitative polymerase chain reaction (qPCR), respectively, varied between the two pipe systems. Nitrogen transformation pathways, identified by path analysis, were also different between the PLSP and CLSP due to different microbial community characteristics and synergistic effects of nitrogen functional genes. In the CLSP, (NH4+-N→NO2 -N) with part denitrification, was the primary transformation pathway of ammonia nitrogen (NH4+-N), while only ammonia oxidization contributed to NH4+-N transformation in the PLSP. (NO2- -N→NO3- -N) was the main pathway involved in NO2- -N transformation and NO3 -N accumulation. The TN removal showed complex relationships with nitrification, denitrification and nitrogen fixation processes. These findings provided molecular-level insights into nitrogen pollutant transformations during the transportation of raw water through different types of pipes and technical support for the selection of raw water pipe materials. In our study area, the Taihu basin, China, PLSP was better than CLSP for distributing raw water in a short transportation distance, due to the lower effluent concentrations of DON and NO3- -N and less abundance of microorganisms.

22507. 题目: Formation of brominated trihalomethanes during chlorination or ozonation of natural organic matter extracts and model compounds in saline water
文章编号: N18071017
期刊: Water Research
作者: Zheng-Qian Liu, Amisha D. Shah, Elisabeth Salhi, Jakov Bolotin, Urs von Gunten
更新时间: 2018-07-10
摘要: Oxidation experiments (chlorine, ozone and bromine) were carried out with synthetic saline waters containing natural organic matter (NOM) extracts and model compounds to evaluate the potential of these surrogates to mimic the formation of brominated trihalomethanes (Br-THMs) in natural saline waters. Synthetic saline water with Pony Lake fulvic acid (PLFA) showed comparable results to natural brackish and sea water for Br-THMs formation during chlorination and ozonation for typical ballast water treatment conditions ([Cl2]0 ≥ 5 mg/L or [O3]0 ≥ 3 mg/L). The molar CHBr3 yield in synthetic saline waters is higher for chlorination than for ozonation, since ozone reacts slower with bromide and faster with THM precursors. For bromination, the molar yields of CHBr3 for the NOM model compounds phenol, resorcinol, 3-oxopentanedioic acid and hydroquinone are 28, 62, 91 and 11%, respectively. CHBr3 formation is low during chlorination or ozonation of resorcinol-containing synthetic saline waters due to the faster reaction of resorcinol with these oxidants compared to the bromine formation from bromide. Oxidation experiments with mixtures of hydroquinone and phenol (or resorcinol) were conducted to mimic various functional groups of NOM reacting with Cl2 (or O3) in saline water. With increasing hydroquinone concentrations, the CHBr3 formation increases during both chlorination and ozonation of the mixtures, except for chlorination of the mixture of hydroquinone and resorcinol. The formation of THMs during chlorination of the mixture of hydroquinone and resorcinol is similar to that of resorcinol alone due to the much faster reaction of HOX with resorcinol compared to hydroquinone. In general, PLFA seems to be a reasonable DOM surrogate to simulate CHBr3 formation for realistic ballast water treatment. During chlorination, CHBr3 formations from phenol- and PLFA-containing synthetic brackish waters are comparable, for similar phenol contents.

22508. 题目: Simultaneous removal of dissolved organic matter and nitrate from sewage treatment plant effluents using photocatalytic membranes
文章编号: N18071016
期刊: Water Research
作者: Hang Xu, Yang Li, Mingmei Ding, Wei Chen, Kang Wang, Chunhui Lu
更新时间: 2018-07-10
摘要: The residual dissolved organic matter (DOM) and nitrate in sewage treatment plant (STP) effluent have potential negative impacts on the aqueous environment. To that end, we used formic acid (FA) to enhance the photochemical behavior of the photocatalytic membrane for the simultaneous removal of DOM and nitrate from secondary STP effluent. Effluent samples were collected from two different biological treatment processes, Anaerobic-Oxic and Anaerobic-Anoxic-Oxic-membrane bioreactor, respectively. Through Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) analysis, we found that the addition of FA resulted in a similar molecular transformation in different STP effluent samples. Besides, the radical signal of the carboxyl anion could be observed during the photocatalytic process. Based on the results, we proposed the mechanism of the process that carboxyl anion radicals generated by FA could attack DOM and result in further oxidation of the DOM transition state to CO2 or small molecule by nitrate. Meanwhile, CHON and CHOS compounds in DOM were attacked by the carboxyl anion radicals more easily than CHO compounds. Moreover, long-term use of the membrane confirmed its durability and reusability in practical applications. At a moderate FA concentration and lower hydraulic retention time, the nitrate and DOM removal efficiencies for the sample from JX STP were 68% and 70%, respectively, whereas those of the CD STP sample were 85% and 60%. The removal of DOM and nitrate from different STP effluents using photocatalytic membranes is an advanced approach for the treatment of secondary effluent, and may be applicable to other membranes or systems.

22509. 题目: Intermolecular interactions of polysaccharides in membrane fouling during microfiltration
文章编号: N18071015
期刊: Water Research
作者: Shujuan Meng, Wenhong Fan, Xiaomin Li, Yu Liu, Dawei Liang, Xiaoxing Liu
更新时间: 2018-07-10
摘要: Membrane technology has been widely employed for seawater desalination, water and wastewater reclamation, while membrane fouling still remains as a major challenge. The polysaccharides in extracellular polymeric substances (EPS) have been recognized as an important foulant that causes serious membrane fouling, while the detailed structure of polysaccharides and the intermolecular interactions between them have not been adequately disclosed. In this study, two different polysaccharides and their mixtures were used to study the intermolecular cross-linking of polysaccharides as well as its effects on membrane fouling. Results demonstrated that the fouling propensities of distinct polysaccharides were completely different, which was attributed to the different intermolecular interactions lying in polysaccharides. The cross-linking among molecules of polysaccharide, regardless of the homogeneity, was found to form complex networks and determine the effective dimension of polysaccharides. Depending on the effective dimension of foulants, pore blocking and cake layer occurred subsequently during filtration processes. In light of this, it potentially gives new insights into the fouling behaviours by combining the structure-function knowledge of polysaccharides with their fouling propensity. In addition, transparent exopolymeric particles (TEP) measurement was found to provide an intuitionistic evaluation of the complex networks formed from polysaccharides, so that may act as a good indicator of fouling during membrane filtration.

22510. 题目: Spatial and temporal shifts in fluvial sedimentary organic matter composition from a High Arctic watershed impacted by localized slope disturbances
文章编号: N18071014
期刊: Organic Geochemistry
作者: David M. Grewer, Melissa J. Lafrenière, Scott F. Lamoureux, Myrna J. Simpson
更新时间: 2018-07-10
摘要: Arctic warming may induce slope failure in upland permafrost soils. These landslide-like events, referred to as active layer detachments (ALDs), redistribute soil material into hydrological networks during spring melt and heavy rainfall. In 2011, 2013 and 2014, fluvial sediments from the West River at the Cape Bounty Arctic Watershed Observatory were sampled where ALDs occurred in 2007–2008. Two ALD-impacted subcatchments were examined exhibiting either continuing disturbance or short-term stabilization. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and targeted biomarker analysis via gas chromatography–mass spectrometry were used to investigate shifts in organic matter (OM) composition. Additionally, radiocarbon ages were determined using accelerator mass spectrometry. Biomarker concentrations and O-alkyl carbon assessed via NMR were both lower in sediments nearest the active disturbance and increased in sediments downstream where other aquatic inputs became more dominant. This suggests immobilization of recalcitrant OM near the ALD and the sustained transport of labile ALD-derived OM further downstream. Shifts toward older radiocarbon dates along the river between 2011 and 2014 suggest the continued transport of permafrost-derived OM downstream. The stabilizing subcatchment revealed high O-alkyl carbon via NMR and increased concentrations of unaltered terrestrial-derived biomarkers indicative of enhanced OM accumulation following ALD activity. The relatively young radiocarbon ages from these sediments suggest accumulation from contemporary sources and potential burial of the previously dispersed ALD inputs. Within the broader context of Arctic climate change, these results portray a complex environmental trajectory for thaw-released permafrost-derived OM and highlight uncertainty in the relationship between lability and persistence upon release by permafrost disturbance.

22511. 题目: A novel method to measure the 13C composition of intact bacteriohopanepolyols
文章编号: N18071013
期刊: Organic Geochemistry
作者: Jordon D. Hemingway, Stephanie Kusch, Sunita R. Shah Walter, Catherine A. Polik, Felix J. Elling, Ann Pearson
更新时间: 2018-07-10
摘要: We present a novel method to measure the 13C/12C isotope ratio (reported as δ13C) of individual, intact bacteriohopanepolyols (BHPs) using semi-preparative ultrahigh pressure liquid chromatography (UPLC) followed by high temperature gas chromatography–isotope ratio mass spectrometry (HT-GC–IRMS). The method is reproducible, as indicated by the precision of δ13C values for bacteriohopanetetrol (BHT) extracted from R. palustris biomass and analyzed across an order-of-magnitude range of IRMS peak areas (δ13C = –33.4 ± 0.6‰ VPDB, n = 94, ± 1σ). To show that this method successfully separates individual BHPs from complex environmental matrices, we report δ13C values for BHT and the BHT stereoisomer (BHT-II) from a ca. 2.9 Ma, organic-rich Mediterranean Sea sediment sample. These analyses suggest that intact BHP δ13C measurements can greatly improve the interpretation of environmental signals by alleviating the need for side-chain cleavage which reduces BHP source-specificity.

22512. 题目: Inactivation of E. coli and E. faecalis by solar photo-Fenton with EDDS complex at neutral pH in municipal wastewater effluents
文章编号: N18071012
期刊: Journal of Hazardous Materials
作者: Irene García-Fernández, Sara Miralles-Cuevas, Isabel Oller, Sixto Malato, Pilar Fernández-Ibá?ez, María Inmaculada Polo-López
更新时间: 2018-07-10
摘要: Photo-Fenton is a solar disinfection technology widely demonstrated to be effective to inactivate microorganisms in water by the combined effect of photoactivated iron species and the direct action of solar photons. Nevertheless, the precipitation of iron as ferric hydroxide at basic pH is the main disadvantage of this process. Thus, challenge in photo-Fenton is looking for alternatives to iron salts. Polycarboxylic acids, such as Ethylendiamine-N‘,N‘-disuccinic acid (EDDS), can form strong complex with Fe3+ and enhance the dissolution of iron in natural water through photochemical process. The aim of this study was to evaluate the disinfection effectiveness of solar photo-Fenton with and without EDDS in water. Several reagent concentrations were assessed, best bacterial (Escherichia coli and Enterococcus faecalis) inactivation was obtained with 0.1:0.2:0.3 mM (Fe3+:EDDS:H2O2) within isotonic water. The benefit of using EDDS complexes to increase the efficiency of kept dissolved iron in water at basic pH was proved. Solar disinfection and H2O2/solar with and without EDDS, and Fe-EDDS complexes were also investigated. Bacterial inactivation results in municipal wastewater effluents (MWWE) demonstrated that the competitive role of organic matter and inorganic compounds strongly affect the efficacy of Fe:EDDS at all concentrations tested, obtaining the faster inactivation kinetics with H2O2/solar (0.3 mM).

22513. 题目: Global-scale evidence for the refractory nature of riverine black carbon
文章编号: N18071011
期刊: Nature Geoscience
作者: Alysha I. Coppola, Daniel B. Wiedemeier, Valier Galy, Negar Haghipour, Ulrich M. Hanke, Gabriela S. Nascimento, Muhammed Usman, Thomas M. Blattmann, Moritz Reisser, Chantal V. Freymond, Meixun Zhao, Britta Voss, Lukas Wacker, Enno Schefu?, Bernhard Peucker-Ehrenbrink, Samuel Abiven, Michael W. I. Schmidt & Timothy I. Eglinton
更新时间: 2018-07-10
摘要: Wildfires and incomplete combustion of fossil fuel produce large amounts of black carbon. Black carbon production and transport are essential components of the carbon cycle. Constraining estimates of black carbon exported from land to ocean is critical, given ongoing changes in land use and climate, which affect fire occurrence and black carbon dynamics. Here, we present an inventory of the concentration and radiocarbon content (∆14C) of particulate black carbon for 18 rivers around the globe. We find that particulate black carbon accounts for about 15.8 ± 0.9% of river particulate organic carbon, and that fluxes of particulate black carbon co-vary with river-suspended sediment, indicating that particulate black carbon export is primarily controlled by erosion. River particulate black carbon is not exclusively from modern sources but is also aged in intermediate terrestrial carbon pools in several high-latitude rivers, with ages of up to 17,000 14C years. The flux-weighted 14C average age of particulate black carbon exported to oceans is 3,700 ± 400 14C years. We estimate that the annual global flux of particulate black carbon to the ocean is 0.017 to 0.037 Pg, accounting for 4 to 32% of the annually produced black carbon. When buried in marine sediments, particulate black carbon is sequestered to form a long-term sink for CO2.

22514. 题目: Electrochemical treatment of butylated hydroxyanisole: Electrocoagulation versus advanced oxidation
文章编号: N18071010
期刊: Separation and Purification Technology
作者: Zhihong Ye, Enric Brillas, Francesc Centellas, Pere Lluís Cabot, Ignasi Sirés
更新时间: 2018-07-10
摘要: This work compares the removal of butylated hydroxyanisole (BHA), a ubiquitous antioxidant in food and pharmaceuticals, from water either by electrocoagulation (EC) with an Fe|Fe cell or H2O2-based electrochemical advanced oxidation processes like electrochemical oxidation (EO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF) with an air-diffusion cathode. BHA degradation by EC was very poor, whereas the dissolved organic carbon (DOC) was more effectively abated in urban wastewater. The effect of pH, number of Fe|Fe pairs and current on the EC performance was examined. The additive was also slowly degraded by EO-H2O2 with a RuO2-based or BDD anode in 50 mM Na2SO4 solution. In the simulated matrix, BHA decay by EO-H2O2 was substantially enhanced owing to active chlorine generation from anodic oxidation of Cl , whereas the OH-mediated oxidation at the BDD surface accounted for DOC decay. In EF and PEF, the OH produced in the bulk upgraded the mineralization, primordially using BDD. In raw urban wastewater at natural pH 7.9, the time course of BHA and DOC contents was affected by NOM oxidation, being accelerated in the order: EO-H2O2 < EF < PEF. The quickest decontamination of urban wastewater occurred in PEF at pH 3.0, because of the higher amounts of OH in the bulk along with UVA photolysis.

22515. 题目: Evaluating the electrochemical and photoelectrochemical production of hydroxyl radical during electrocoagulation process
文章编号: N18071009
期刊: Separation and Purification Technology
作者: Alejandro Medel, José A. Ramírez, Jesús Cárdenas, Ignasi Sirés, Yunny Meas
更新时间: 2018-07-10
摘要: In this study, we evaluate for the first time the effect of ionic composition on the anodic production of hydroxyl radical (OHa) during electrocoagulation (EC) process in batch using carbon steel electrodes. Likewise, hydroxyl radical production from active chlorine (OHph) electrogenerated in EC photoassisted with UVA (λ = 365 nm) and UVC light (λ = 254 nm) was evaluated using car wash wastewater. Both, OHa and OHph, were analyzed by UV–Vis spectroscopy and fluorescence using coumarin as the probe. Under optimal conditions (j = 8 mA cm-2, 25 °C, 15 min, 6 rpm), turbidity, suspended solids and color were removed by 98.3%, 98.7% and 93.1%, respectively. However, total organic carbon (TOC) abatement only attained 27%. This can be related to the fact that OHa and OHph were not identified during EC, with or without UV irradiation. Hence, the organic matter is mainly removed by coagulation with Fe(OH)n species. Comparative treatment of the same wastewater by electrochemical oxidation (EO) with a Ti|IrO2-Ta2O5 anode in the presence of electrogenerated active chlorine and UVC light demonstrated the generation of OHph, thus encouraging the potential coupling of EC with EO.

22516. 题目: Late Holocene record from a Loire River incised paleovalley (French inner continental shelf): Insights into regional and global forcing factors
文章编号: N18071008
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: M. Durand, M. Mojtahid, G.M. Maillet, A. Baltzer, S. Schmidt, S. Blet, E. Marchès, H. Howa
更新时间: 2018-07-10
摘要: Sediment core KV14bis was retrieved from the Fosse du Croisic, a Loire River incised paleovalley located in the inner shelf of the Bay of Biscay. This core (5.4 m length) covers the past 2.6 cal kyr BP with high sedimentation rate. A multiproxy approach (X-ray imagery, XRF data, grain size analyses, and benthic foraminiferal assemblages) was applied in order to reconstruct the hydrological regime of the Loire River during the late Holocene. This hydrological regime was further linked to climate forcing (e.g. solar activity, North Atlantic Oscillation - NAO) and human activity. Our data describe a succession of several dry/humid periods. The humid periods are centered on ~2.2, 1.3, and 0.5 cal kyr BP and are characterized by high terrigenous flux, fine silty sedimentation, relatively high organic carbon content and high proportions of the epiphytic foraminiferal species Planorbulina mediterranensis. This species was probably brought to the study site by the Loire River plume, attached on floating algae. The dry periods are centered on ~2.5, 1.5, 1.2 cal kyr BP and 1900 CE and are characterized by low terrigenous input, and high carbonate content due to abundant shell debris. During periods of low river runoff, deposition of a sand-particle population (grain size ~200 μm) could indicate increased storminess. This latter may have remobilized sediments from shallower depths during these generally dry periods on the continent. The overall coherence of our results with several European continental records supports a pluri-centennial scale regional climate control of humidity and storminess resembling that of the NAO. Spectral analyses emphasized a possible additional control of solar activity. Through deforestation and soil erosion, early human impact was also probably superimposed on this climatic forcing.

22517. 题目: Microbial carbon use efficiency and priming effect regulate soil carbon storage under nitrogen deposition by slowing soil organic matter decomposition
文章编号: N18071007
期刊: Geoderma
作者: Weixing Liu, Chunlian Qiao, Sen Yang, Wenming Bai, Lingli Liu
更新时间: 2018-07-10
摘要: Microbial carbon use efficiency (CUE) strongly influences the rate of soil organic carbon (SOC) formation by mediating C loss via microbial respiration, whereas the priming effect plays a crucial role in regulating the stability of SOC. Nitrogen (N) deposition increases N availability and alters litter quality and quantity, both of which could strongly affect the CUE and priming effect. However, it remains unclear whether and how, under N deposition, the CUE and priming effect could affect soil C cycling. In this study, we conducted a consecutive 12-yr N addition experiment in a temperate steppe. We evaluated how increasing N inputs affect soil C accumulation, microbial respiration, microbial biomass and composition in the field. We also performed an incubation experiment by adding 13C labeled glucose and phenol to the pre-incubated soils to test how N addition affects microbial CUE and the priming effects on stable soil C. Our field experiment showed that N addition increased soil organic C concentration and decreased soil microbial respiration, microbial total phospholipid fatty acids (PLFAs), and fungi to bacteria (F:B) ratio. Our incubation experiments indicated that N addition increased microbial CUE of glucose but decreased that of phenol. The priming effects of both glucose and phenol were suppressed by N addition. Redundancy analysis (RDA) showed the importance of fungi in regulating microbial CUE and priming effect. Specifically, multi-model averaging suggested that the decreased fungal biomass under N addition was the most important predictor for changes in CUE of glucose, while decreased fungal biomass and F:B ratio were the most important predictors for changes in the CUE and priming effects. In addition, the increased CUE of glucose best explained the decreased microbial respiration, and the reduced priming effect of glucose best explained the increased SOC under N addition. Overall, our finding suggested that N addition would alter microbial CUE and the priming effects on stable soil C. The different responses of CUE and priming effects to glucose and phenol addition imply that the decreased microbial respiration and increased C storage under N deposition could be more attributed to labile C inputs rather than recalcitrant C inputs.

22518. 题目: Exposure to ZnO nanoparticles alters neuronal and vascular development in zebrafish: Acute and transgenerational effects mitigated with dissolved organic matter
文章编号: N18071006
期刊: Environmental Pollution
作者: Shimaa M. Kteeba, Ahmed E. El-Ghobashy, Hala I. El-Adawi, Osman A. El-Rayis, Virinchipuram S. Sreevidya, Laodong Guo, Kurt R. Svoboda
更新时间: 2018-07-10
摘要: Exposure to ZnO-nanoparticles (NPs) in embryonic zebrafish reduces hatching rates which can be mitigated with dissolved organic material (DOM). Although hatching rate can be a reliable indicator of toxicity and DOM mitigation potential, a fish that has been exposed to ZnO-NPs or any other toxicant may also exhibit other abnormal phenotypes not readily detected by the unaided eye. In this study, we moved beyond hatching rate analysis to investigate the consequences of ZnO-NPs exposure on the nervous and vascular systems in developing zebrafish. Zebrafish exposed to ZnO-NPs (1–100 ppm) exhibited an array of cellular phenotypes including: abnormal secondary motoneuron (SMN) axonal projections, abnormal dorsal root ganglion development and abnormal blood vessel development. Dissolved Zn (<10 kDa) exposure also caused abnormal SMN axonal projections, but to a lesser extent than ZnO-NPs. The ZnO-NPs-induced abnormal phenotypes were reversed in embryos concurrently exposed with various types of DOM. In these acute mitigation exposure experiments, humic acid and carbohydrate, along with natural organic matter obtained from the Suwannee River in Georgia and Milwaukee River in Wisconsin, were the best mitigators of ZnO-NPs-induced motoneuron toxicity at 96 h post fertilization. Further experiments were performed to determine if the ZnO-NPs-induced, abnormal axonal phenotypes and the DOM mitigated axonal phenotypes could persist across generations. Abnormal SMN axon phenotypes caused by ZnO-NPs-exposure were detected in F1 and F2 generations. These are fish that have not been directly exposed to ZnO-NPs. Fish mitigated with DOM during the acute exposure (F0 generation) had a reduction in abnormal motoneuron axon errors in larvae of subsequent generations. Therefore, ZnO-NPs exposure results in neurotoxicity in developing zebrafish which can persist from one generation to the next. Mitigation with DOM can reverse the abnormal phenotypes in an acute embryonic exposure context, as well as across generations, resulting in healthy fish.

22519. 题目: Geochemical indices and regression tree models for estimation of ambient background concentrations of copper, chromium, nickel and zinc in soil
文章编号: N18071005
期刊: Chemosphere
作者: Hannah G. Mikkonen, Robert van de Graaff, Bradley O. Clarke, Raghava Dasika, Christian J. Wallis, Suzie M. Reichman
更新时间: 2018-07-10
摘要: Geochemical ratios between elements of environmental concern and Fe have been recommended for estimation of “background” concentrations of Cr, Cu, Ni and Zn in soil. However, little research has occurred to assess the consistency of geochemical ratios across soils developed in different environments. Broad application of generic geochemical ratios could result in under or over estimation of anthropogenic impacts to soil and subsequent inaccurate assessment of risk to the environment. A soil survey was undertaken in Victoria, Australia, including collection of samples (n = 622) from surface (0–0.1 m below ground level) and sub-surface (0.3–0.6 m below ground level) soils, overlying Tertiary-Quaternary basalt, Tertiary sediments and Silurian siltstones and sandstones. Samples were analyzed for metals and soil physical and chemical properties (particle size, cation exchange capacity, organic matter and pH). Geochemical correlations between elements in soils from different parent materials and environments were compared against geochemical relationships reported in Australia and internationally. Ratios of Cr and Fe were relatively consistent across parent materials, and comparable to published models for estimation of background Cr. Conversely, ratios between Cu, Ni, and Zn with Fe, were variable between soils developed in different weathering environments and/or soil depths. Alternative regression equations and rule based regression tree models were developed as an improved means for prediction of ambient background Cu, Ni and Zn concentrations in soil. Ambient background concentrations of Ni and Cr were predictable across parent materials and depths, allowing these models to be extended to soils across Australia and potentially internationally.

22520. 题目: Pesticide fate in cultivated mountain basins: The improved DynAPlus model for predicting peak exposure and directing sustainable monitoring campaigns to protect aquatic ecosystems
文章编号: N18071004
期刊: Chemosphere
作者: Melissa Morselli, Elisa Terzaghi, Filippo Galimberti, Antonio Di Guardo
更新时间: 2018-07-10
摘要: Agricultural activities can involve the use of plant protection products (PPPs) and the use of such chemicals can occur near surface waters bodies, thus creating a potential for adverse effects on aquatic ecosystems. In mountain watersheds, where runoff fluxes are particularly rapid due to side slopes, exposure is generally characterized by short but intense concentration peaks. Monitoring campaigns are often inadequate or too expensive to be carried out and modelling tools are therefore vital for exposure assessment and their use is encouraged by current legislation. However, currently adopted models and scenarios (e.g., FOCUS for PPPs) are often too conservative and/or “static” to accurately capture exposure variability, and the need for more realistic and dynamic tools is now one of the major challenges for risk assessment. In a previous work, the new fate model DynAPlus was developed to improve pesticide fate predictions in cultivated mountain basins and was successfully evaluated against chlorpyrifos water concentrations measured in a mountain stream in Northern Italy. However, the need for some model improvements (e.g., the inclusion of dissolved organic matter and macrophytes in water) was highlighted. In this work, DynAPlus was improved by replacing the water-sediment unit with ChimERA fate, a recently-published model capable of predicting bioavailable chemical concentrations in shallow water environments accounting for the presence and temporal variations of particulate/dissolved organic carbon and primary producers. The model was applied to preliminarily characterize the risk associated to the use of four PPPs (two insecticides and two fungicides) in a sub-basin of the Adda River (Valtellina Valley, Northern Italy), surrounded by apple orchards. Results revealed the potential magnitude of exposure peaks for the four PPPs and suggested that monitoring campaigns should prioritize, in the selected case study, chlorpyrifos, etofenprox and fluazinam. The potential role of DynAPlus in providing more realistic exposure predictions for ecological risk assessment, as well as for planning efficient monitoring campaigns and help pesticide management practices, was also stressed.

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