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28901. 题目: Non-Redfieldian mesopelagic nutrient remineralization in the eastern North Atlantic subtropical gyre
文章编号: N18121111
期刊: Progress in Oceanography
作者: Bieito Fernández-Castro, Beatriz Mouriño-Carballido, Xosé Antón Álvarez-Salgado
更新时间: 2018-12-11
摘要: The eastern boundary of the North Atlantic subtropical gyre (NASTG) receives organic materials produced in the nearby Canary upwelling system (CanUS), which has important implications for the metabolic balance of the region. Here we computed absolute geostrophic, Ekman and eddy diffusive transports and net budgets of oxygen, nitrate, and phosphate, with an inverse model applied to annual climatologies from the World Ocean Atlas 2013, in a large box covering the eastern boundary of the NASTG. The surface waters (<100 m) of the box exported mol O2 m-2 yr-1 to the adjacent ocean and atmosphere, and imported mol N m-2 yr-1 and mmol P m-2 yr-1 of nitrate and phosphate, respectively, indicating that net autotrophy prevailed in the euphotic waters of the eastern NASTG. The central, intermediate and deep waters (100 m-bottom) imported mol O2 m-2 yr-1, and exported mol N m-2 yr-1 and mmol P m-2 yr-1 of nitrate and phosphate, respectively, indicative of net remineralization. Mesopelagic remineralization rates exceeded epipelagic net community production, implying a net deficit of carbon and nutrients in the region. Remineralization occurred at high N:P molar ratios (28) in central waters, and thus, a excess nitrate (DINxs = NO3-16PO4) was produced at a rate of 1011 mol N yr-1. This excess nitrate was exported to the gyre interior, influencing the biogeochemistry of the whole NASTG and leaving the eastern margin with a strong nitrogen deficit, relative to carbon and phosphorus. According to the available literature, the organic carbon export from the CanUS could be sufficient to account for the carbon deficit, but the source of nitrogen remains elusive.
28902. 题目: Performance and microbial community analysis of an algal-activated sludge symbiotic system: Effect of activated sludge concentration
文章编号: N18121110
期刊: Journal of Environmental Sciences
作者: Li Sun, Wei Zuo, Yu Tian, Jun Zhang, Jia Liu, Ni Sun, Jianzheng Li
更新时间: 2018-12-11
摘要: It was focused on the effect of different sludge concentrations on the performances of an algal-activated sludge symbiotic system in terms of wastewater treatment, algal-activated sludge characteristics and community structure. The results showed that the highest nutrient removal efficiencies were obtained in the reactor R2 with soluble chemical oxygen demand (sCOD), ammonia nitrogen (NH4+-N) and phosphate (PO43 − -P) removal efficiencies of (90.6 ± 2.3)%, (97.69 ± 2.6)% and (83.81 ± 2.3)%, respectively. Further investigation exhibited that sludge concentration has a great effect on the dissolved oxygen (DO) concentration, the pH, the growth of algae and the extracellular polymeric substance (EPS) production, which resulted in influencing the settleability and the performance of symbiotic system. The denaturing gradient gel electrophoresis (DGGE) analysis demonstrated that the sludge concentration had a selective power for particular members of algae. Meantime, the stimulated algal population would selectively excite the members of bacteria benefited for the formation of algal-bacterial consortia. The variation of microbial compositions, which was influenced by the different sludge concentrations, might be ultimately responsible for the different treatment performances.
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28903. 题目: Insight into the distribution of metallic elements in membrane bioreactor: Influence of operational temperature and role of extracellular polymeric substances
文章编号: N18121109
期刊: Journal of Environmental Sciences
作者: He Wang, Xiufen Li, Xinhua Wang, Yueping Ren
更新时间: 2018-12-11
摘要: The distribution of metallic elements in a submerged membrane bioreactor (MBR) was revealed at different temperatures using inductively coupled plasma-optical emission spectrometry (ICP-OES), and the role of extracellular polymeric substances (EPS) was probed by integrating scanning electron microscopy (SEM) with confocal laser scanning microscopy (CLSM) over long-term operation. More metallic elements in the influent were captured by suspended sludge and built up in the fouling layer at lower temperature. The concentration of metallic elements in the effluent was 5.60 mg/L at 10°C operational temperature, far lower than that in the influent (51.35 mg/L). The total contents of metallic elements in suspended sludge and the membrane fouling layer increased to 40.20 and 52.19 mg/g at 10°C compared to 35.14 and 32.45 mg/g at 30°C, and were dominated by the organically bound fraction. The EPS contents in suspended sludge and membrane fouling layer sharply increased to 37.88 and 101.51 mg/g at 10°C, compared to 16.87 and 30.03 mg/g at 30°C. The increase in EPS content at lower temperature was responsible for the deposition of more metallic ions. The strong bridging between EPS and metallic elements at lower temperature enhanced the compactness of the fouling layer and further decreased membrane flux. This was helpful for understanding the mechanism of membrane fouling at different operational temperatures and the role of EPS, and also of significance for the design of cleaning strategies for fouled membranes after long-term operation.
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28904. 题目: Tracking the reactivity of ozonation towards effluent organic matters from WWTP using two-dimensional correlation spectra
文章编号: N18121108
期刊: Journal of Environmental Sciences
作者: Xin Jin, Weijie Zhang, Rui Hou, Pengkang Jin, Jina Song, Xiaochang C. Wang
更新时间: 2018-12-11
摘要: The characteristics of effluent organic matter (EfOM) from a wastewater treatment plant (WWTP) during ozonation were investigated using excitation and emission matrix (EEM) spectra, Fourier transform infrared spectroscopy (FT-IR) and high-performance size exclusion chromatography (HPSEC) at different ozone dosages. The selectivity of ozonation towards different constituents and functional groups was analysed using two-dimensional correlation spectra (2D-COS) probed by FT-IR, synchronous fluorescence spectra and HPSEC. The results indicated that ozonation can destroy aromatic structures of EfOM and change its molecular weight distribution (MWD). According to 2D-COS analysis, microbial humic-like substances were preferentially removed, and then the protein-like fractions. Terrestrial humic-like components exhibited inactivity towards ozonation compared with the above two fractions. Protein-like substances with small molecular weight were preferentially reacted during ozonation based on 2D-COS probed by HPSEC. In addition, the selectivity of ozone towards different functional groups of EfOM exhibited the following sequence: phenolic and alcoholic CO groups > aromatic structures containing CC double bonds > aliphatic CH. X-ray photoelectron spectroscopy (XPS) further elucidated the preferential reaction of aromatic structures in EfOM during ozonation.
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28905. 题目: Preferential binding between intracellular organic matters and Al13 polymer to enhance coagulation performance
文章编号: N18121107
期刊: Journal of Environmental Sciences
作者: Ruiping Liu, Tingting Guo, Min Ma, Mingquan Yan, Jing Qi, Chengzhi Hu, Gang Liu, Huijuan Liu, Jiuhui Qu, Walter van der Meer
更新时间: 2018-12-11
摘要: Coagulation is the best available method for removing intracellular organic matter (IOM), which is released from algae cells and is an important precursor to disinfection by-products in drinking water treatment. To gain insight into the best strategy to optimize IOM removal, the coagulation performance of two Al salts, i.e., aluminum chloride (AlCl3) and polyaluminum chloride (PACl, containing 81.2% Al13), was investigated to illuminate the effect of Al species distribution on IOM removal. PACl showed better removal efficiency than AlCl3 with regard to the removal of turbidity and dissolved organic carbon (DOC), owing to the higher charge neutralization effect and greater stability of pre-formed Al13 species. High pressure size exclusion chromatography analysis indicated that the superiority of PACl in DOC removal could be ascribed to the higher binding affinity between Al13 polymer and the low and medium molecular weight (MW) fractions of IOM. The results of differential log-transformed absorbance at 254 and 350 nm indicated more significant formation of complexes between AlCl3 and IOM, which benefits the removal of tryptophan-like proteins thereafter. Additionally, PACl showed more significant superiority compared to AlCl3 in the removal of < 5 kDa and hydrophilic fractions, which are widely viewed as the most difficult to remove by coagulation. This study provides insight into the interactions between Al species and IOM, and advances the optimization of coagulation for the removal of IOM in eutrophic water.
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28906. 题目: Kinetic and thermodynamic studies on partitioning of polychlorinated biphenyls (PCBs) between aqueous solution and modeled individual soil particle grain sizes
文章编号: N18121106
期刊: Journal of Environmental Sciences
作者: Gbadebo Clement Adeyinka, Brenda Moodley
更新时间: 2018-12-11
摘要: The significance of soil mineral properties and secondary environmental conditions such as pH, temperature, ionic strength and time in the partitioning of eight selected polychlorinated biphenyl (PCB) congeners between aqueous solution and soil particles with different grain sizes was studied. The mineral properties of a model soil sample were determined, and Brunauer–Emmett–Teller (BET) adsorption–desorption isotherms were employed to observe the surface characteristics of the individual modeled soil particles. Batch adsorption experiments were conducted to determine the sorption of PCBs onto soil particles of different sizes. The results revealed that the sorption of PCB congeners onto the soil was dependent on the amount of soil organic matter, surface area, and pore size distribution of the various individual soil particles. Low pH favored the sorption of PCBs, with maximum sorption occurring between pH 6.5 and 7.5 with an equilibration period of 8 hr. Changes in the ionic strength were found to be less significant. Low temperature favored the sorption of PCBs onto the soil compared to high temperatures. Thermodynamic studies showed that the partition coefficient (Kd) decreased with increasing temperature, and negative and low values of ΔH° indicated an exothermic physisorption process. The data generated is critical and will help in further understanding remediation and cleanup strategies for polluted water.
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28907. 题目: Effects of effluent organic matters on endocrine disrupting chemical removal by ultrafiltration and ozonation in synthetic secondary effluent
文章编号: N18121105
期刊: Journal of Environmental Sciences
作者: Xiurong Si, Zunfang Hu, Ding Ding, Xu Fu
更新时间: 2018-12-11
摘要: Endocrine disrupting chemicals (EDCs) in the secondary effluent discharged from wastewater treatment plants are of great concern when water reuse is intended. Ozonation and ultrafiltration (UF) are powerful technologies reported to eliminate EDCs. Due to the importance of effluent organic matters (EfOMs) in secondary effluent, the effects of three kinds of EfOM on the treatment of five EDCs using ozonation and UF were investigated. The three kinds of EfOM studied were humic acid sodium salt (NaAH), bovine serum albumin (BSA) and sodium alginate (NaAg); and the five EDCs were estrone, 17β-estradiol, estriol, 17α-ethynyl estradiol and bisphenol A. The results showed that EfOM accelerated the decay rate of ozone and inhibited the degradation efficiency of EDCs by ozonation in the order NaAH > BSA > NaAg. The ultraviolet absorbance at 280 nm (UVA280) has potential for use as a surrogate indicator to assess EDC removal via ozonation without conducting difficult EDC analyses. When the decline in UVA280 exceeded 18%, the five EDCs had been completely removed. The UF behavior of NaAH, BSA and NaAg was found to follow the cake filtration law. The fouling potential of EfOM followed the order NaAg > NaAH > BSA; while EfOM on the membrane surface enhanced EDC removal in the order NaAH > BSA > NaAg. The mean retention rate of the membrane was increased by 24%, 10% and 8%, respectively. The properties of EDCs and EfOM cakes both influenced the EDC removal rates due to adsorption, size exclusion and charge attraction.
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28908. 题目: Effect of manganese oxide-modified biochar addition on methane production and heavy metal speciation during the anaerobic digestion of sewage sludge
文章编号: N18121104
期刊: Journal of Environmental Sciences
作者: Jianhua Li, Min Zhang, Zhiyin Ye, Changming Yang
更新时间: 2018-12-11
摘要: Low organic matter content and high heavy metal levels severely inhibit the anaerobic digestion (AD) of sewage sludge. In this study, the effect of added manganese oxide-modified biochar composite (MBC) on methane production and heavy metal fractionation during sewage sludge AD was examined. The MBC could increase the buffering capacity, enhance the methane production and degradation of intermediate acids, buffer the pH of the culture, and stabilize the sewage sludge AD process. The application of MBC positively impacted methane production and the cumulative methane yield increased up to 121.97%, as compared with the control. The MBC addition can improve metal stabilization in the digestate. An optimum MBC dose of 2.36 g was recommended, which would produce up to 121.1 L/kg volatile solids of methane. After the AD process, even though most of the metals accumulated in the residual solids, they could be transformation from the bio-available fractions to a more stable fraction. The total organic- and sulfide-bound and residual fraction content at a 3 g dose of MBC that is 0.12 g/g dry matter were 51.06% and 35.11% higher than the control, respectively. The results indicated that the application of MBC could improve the performance of AD and promote stabilization of heavy metals in sewage sludge post the AD process.
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28909. 题目: Shifts of soil microbial community composition along a short-term invasion chronosequence of Spartina alterniflora in a Chinese estuary
文章编号: N18121103
期刊: Science of The Total Environment
作者: Guangliang Zhang, Junhong Bai, Jia Jia, Wei Wang, Xin Wang, Qingqing Zhao, Qiongqiong Lu
更新时间: 2018-12-11
摘要: Exotic plant invasion can alter native soil microbial community composition, and further influence the biogeochemical processes. Little information is available about the impacts of the invasion chronosequence of Spartina alterniflora on the dynamics of soil microbial community. Soil microbial community in coastal salt marshes invaded by S. alterniflora and reference wetlands covered by Suaeda salsa were investigated using phospholipid fatty acids (PLFAs) profiling along a short-term chronosequence (i.e., 2-, 5- and 10-year) of S. alterniflora invasion in the Yellow River Estuary. Results exhibited an increase in soil moisture, soil organic matter (SOM), soil dissolved organic carbon (DOC), total nitrogen (TN) and the total of PLFAs with increasing invasion ages of S. alterniflora in these coastal salt marshes. Comparatively, soil pH and bulk density exhibited a weak decline along the invasion chronosequence. The elevated values of relative abundance of fungi and the ratios of fungi: bacteria (F/B) in all invaded salt marshes were mainly associated with the accumulation of soil available substrate (e.g., SOM, DOC and TN). S. alterniflora invasion also increased the ratios of gram-positive/gram-negative (G+/G-) bacterial PLFAs, with the highest value occurring in the 2-year invaded salt marshes. The bacterial stress indicated by ratios of cy17:0/16:1ω7c and cy19:0/18:1ω7c consistently decreased along the invasion chronosequence. In conclusion, the shifts of soil microbial community composition were tightly associated with soil variables, such as soil pH and soil nutrient supply. Our findings reflect the short-term chronological effects of S. alterniflora invasion on the soil physicochemical characteristics and microbial communities, which contributes to the linkage between the plant invasion and soil development of coastal salt marshes.
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28910. 题目: Permafrost landslides promote soil CO2 emission and hinder C accumulation
文章编号: N18121102
期刊: Science of The Total Environment
作者: O.V. Masyagina, S.Yu. Evgrafova, T.N. Bugaenko, V.V. Kholodilova, L.V. Krivobokov, M.A. Korets, D. Wagner
更新时间: 2018-12-11
摘要: Landslides are common in high-latitude forest ecosystems that have developed on permafrost. The most vulnerable areas in the permafrost territories of Siberia occur on the south-facing slopes of northern rivers, where they are observed on about 20% of the total area of river slopes. Landslide disturbances will likely increase with climate change especially due to increasing summer–autumn precipitation. These processes are the most destructive natural disturbance agent and lead to the complete removal of pre-slide forest ecosystems (vegetation cover and soil). To evaluate postsliding ecosystem succession, we undertook integrated ecological research at landslides of different age classes along the Nizhnyaya Tunguska River and the Kochechum River (Tura, Krasnoyarsk region, Russia). Just after the event (at the one-year-old site), we registered a drop in soil respiration, a threefold lower microbial respiration rate, and a fourfold smaller mineral soil carbon and nitrogen stock at bare soil (melkozem) plots at the middle location of the site as compared with the non-affected control site. The recovery of disturbed areas began with the re-establishment of plant cover and the following accumulation of an organic soil layer. During the 35-year succession (L1972), the accumulated layer (O-layer) at the oldest site contained similar C- and N stocks to those found at the control sites. However, the mineral soil C- and N stocks and the microbial biomass – even of the oldest landslide area – did not reach the value of these parameters in control plots. Later, the soil respiration level and the eco-physiological status of soil microbiota also recovered due to these changes. This study demonstrates that the recovery after landslides in permafrost forests takes several decades. In addition, the degradation of permafrost due to landslides clearly hinders the accumulation of soil organic matter in the mineral soil.
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28911. 题目: An affordable and reliable assessment of aquatic decomposition: Tailoring the Tea Bag Index to surface waters
文章编号: N18121101
期刊: Water Research
作者: Laura M.S. Seelen, Giovanna Flaim, Joost Keuskamp, Sven Teurlincx, Raquel Arias Font, Duygu Tolunay, Markéta Fránková, Kateřina Šumberová, Maria Temponeras, Mirjana Lenhardt, Eleanor Jennings, Lisette N. de Senerpont Domis
更新时间: 2018-12-11
摘要: Litter decomposition is a vital part of the global carbon cycle as it determines not only the amount of carbon to be sequestered, but also how fast carbon re-enters the cycle. Freshwater systems play an active role in the carbon cycle as it receives, and decomposes, terrestrial litter material alongside decomposing aquatic plant litter. Decomposition of organic matter in the aquatic environment is directly controlled by water temperature and nutrient availability, which are continuously affected by global change.We adapted the Tea Bag Index (TBI), a highly standardized methodology for determining soil decomposition, for lakes by incorporating a leaching factor. By placing Lipton pyramid tea bags in the aquatic environment for 3 hours, we quantified the period of intense leaching which usually takes place prior to litter (tea) decomposition. Standard TBI methodology was followed after this step to determine how fast decomposition takes place (decomposition rate, k1) and how much of the material cannot be broken down and is thus sequestered (stabilization factor, S). A Citizen Science project was organized to test the aquatic TBI in 40 European lakes located in four climate zones, ranging from oligotrophic to hypereutrophic systems. We expected that warmer and/or eutrophic lakes would have a higher decomposition rate and a more efficient microbial community resulting in less tea material to be sequestered.The overall high decomposition rates (k1) found confirm the active role lakes play in the global carbon cycle. Across climate regions the lakes in the warmer temperate zone displayed a higher decomposition rate (k1) compared to the colder lakes in the continental and polar zones. Across trophic states, decomposition rates were higher in eutrophic lakes compared to oligotrophic lakes. Additionally, the eutrophic lakes showed a higher stabilization (S), thus a less efficient microbial community, compared to the oligotrophic lakes, although the variation within this group was high. Our results clearly show that the TBI can be used to adequately assess the decomposition process in aquatic systems. Using “alien standard litter” such as tea provides a powerful way to compare decomposition across climates, trophic states and ecosystems.By providing standardized protocols, a website, as well as face to face meetings, we also showed that collecting scientifically relevant data can go hand in hand with increasing scientific and environmental literacy in participants. Gathering process-based information about lake ecosystems gives managers the best tools to anticipate and react to future global change. Furthermore, combining this process-based information with citizen science, thus outreach, is in complete agreement with the Water Framework Directive goals as set in 2010.
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28912. 题目: Impact of dense bottom water on a continental shelf: An example from the SW Adriatic margin
文章编号: N18121009
期刊: Marine Geology
作者: M. Rovere, C. Pellegrini, J. Chiggiato, E. Campiani, F. Trincardi
更新时间: 2018-12-10
摘要: Dense shelf waters have been recognised as a key factor in transporting sediment and organic matter across continental slopes; however, the effect of their circulation on continental shelves is still overlooked. The Adriatic Sea is one of the areas in the Mediterranean where dense shelf water forms and flows as a bottom-hugging gravity current along the continental margin. A fraction of this dense water passes beyond the shelf break and flows downslope through cascading, while a large (lighter and faster) portion remains on the shelf, with a principal vein flowing between 80 and 120 m water depth.This paper presents the 3D shape, internal architecture and sediment facies of a variety of large-scale sedimentary features detected on the continental shelf and at the shelf edge, between 50 and 300 m water depth. These features include giant comet marks, large flute-shaped scours, muddy sediment waves, very large dunes with superimposed bedforms, active and relict sand ridges and shelf edge contourites. Both erosional and depositional features show an overall internal geometry and orientation consistent with water masses flowing southward, and are located where flows become accelerated by topographic constraints and deviated by the curvature of the shelf edge.In this study, the morphology and seismic stratigraphic structure of large-scale bedforms are investigated in an effort to place constraints on bedform evolution and preservation, especially as predictive tools for sand resource management, and to bring new evidence of the interaction between unidirectional hydrodynamic processes and seafloor dynamics on the shelf.
28913. 题目: Assimilate allocation by rice and carbon stabilisation in soil: effect of water management and phosphorus fertilisation
文章编号: N18121008
期刊: Plant and Soil
作者: Cornelius Talade Atere, Tida Ge, Zhenke Zhu, Shoulong Liu, Xizhi Huang, Olga Shibsitova, Georg Guggenberger, Jinshui Wu
更新时间: 2018-12-10
摘要: Background and aims: Water and nutrient management influences the allocation and stabilisation of newly assimilated carbon (C) in paddy soils. This study aimed to determine the belowground allocation of C assimilated by rice and the subsequent C stabilisation in soil aggregates and as mineral-organic associates depending on combined alternate wetting and drying (AWD) versus continuous flooding (CF) and P fertilisation. Methods: We continuously labelled rice plants in 13CO2 atmosphere under AWD versus CF water management, and at two P fertilisation levels (0 or 80 mg P kg−1 soil). The 13C allocation to soil and its incorporation into the wet-sieved aggregate size classes and density fractions of the rhizosphere and bulk soils were analysed 6, 14, and 22 days after the labelling was started (D6, D14, and D22, respectively). Results: Under both water regimes and P fertilisation levels, the proportion of photoassimilates was the highest in the silt- and clay-size aggregate classes and in the mineral-associated fraction. On D6 and D14, P fertilization resulted in smaller 13C incorporation into soil, independent of water management. In the rhizosphere soil, at D22, P fertilisation increased 13C incorporation over no P amendment in macroaggregates (>250 μm) by 32% (AWD) and 42% (CF), in microaggregates (250–53 μm) by 97% (CF), and in the silt + clay size class (<53 μm) by 83% (CF). Further, P fertilisation led to larger 13C incorporation into the rhizosphere soil light fraction (75% at AWD and 90% at CF) and dense fraction (38% and 45%, respectively), and into the bulk soil macroaggregates (71% and 78%, respectively). Conclusions: Phosphorus fertilisation increased the contents of recent photoassimilates in soil aggregate classes with longer residence time as well as of the particulate organic matter with the continuation of plant growth. This positive response of the stabilisation of recent plant photosynthates in soil to P fertilisation can increase the potential of paddy soil for C sequestration. This potential is not limited by the introduction of alternate wetting and drying water-saving technique.
28914. 题目: Insight into enhanced carbamazepine photodegradation over biochar-based magnetic photocatalyst Fe3O4/BiOBr/BC under visible LED light irradiation
文章编号: N18121007
期刊: Chemical Engineering Journal
作者: Shan Li, Zhaowei Wang, Xiating Zhao, Xing Yang, Guiwei Liang, Xiaoyun Xie
更新时间: 2018-12-10
摘要: A novel, economical and magnetically separable heterojunction photocatalyst Fe3O4/BiOBr stacked on reed straw biochar (Fe3O4/BiOBr/BC) with visible light response was successfully prepared via a facile modified one-step hydrolysis method for the first time. The target pollutant carbamazepine (CBZ) was used to further investigate the photocatalytic activity of Fe3O4/BiOBr/BC. Compared with BiOBr and Fe3O4/BiOBr, novel photocatalyst Fe3O4/BiOBr/BC owing to the introduction of biochar exhibited better photocatalytic activity (95.51%) of CBZ photodegradation even under 50 W energy-saving visible LED light irradiation. Additionally, effect of pH on CBZ photodegradation using Fe3O4/BiOBr/BC was insignificant meaning wider practical application. Besides, three common anions (Cl−, NO3−, SO42−) and DOM existing in natural water exhibited beneficial or detrimental effects to some extent. Free radicals trapping experiments results illustrated high carbamazepine removal efficiency could be ascribed to superoxide radicals and hydroxyl radicals. The transformation intermediates of CBZ were determined by HRMS and the possible photodegradation pathways were proposed. Finally, good reusability and stability verified the excellent practicality and feasibility of Fe3O4/BiOBr/BC for removal of organic pollutants in aqueous.
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28915. 题目: Hydroxylamine-assisted catalytic degradation of ciprofloxacin in ferrate/persulfate system
文章编号: N18121006
期刊: Chemical Engineering Journal
作者: Chen Li, Hui Lin, Andac Armutlulu, Ruzhen Xie, Yongli Zhang, Xiaoyang Meng
更新时间: 2018-12-10
摘要: In this study, ferrate (Fe(VI)) was used as catalyst to activate persulfate (PS) for the removal of ciprofloxacin (CIP) from aqueous solution. Hydroxylamine (HA) was used to accelerate the reduction and regeneration of Fe(II) from the Fe(VI) + PS system. It was found that 91.5% of 30 μM CIP was decomposed within 60 min in the PS + Fe(VI)/HA system, which is 25.9% higher than that in the PS + Fe(VI) system. In the PS + Fe(VI)/HA system, the removal of CIP increased with the decrement of initial solution pH, whereas inorganic anions (i.e. HCO3−, Cl−, NO3− ions) and humic acid had slightly inhibitory effects on CIP removal. The radical scavenging experiments and the electron paramagnetic resonance (ESR) tests confirmed that the addition of HA in the PS + Fe(VI) system can accelerate the generation of reactive oxygen species (ROS) such as sulfate radicals (SO4−) and hydroxyl radicals (OH), which played important roles for the removal of CIP in the PS + Fe(VI)/HA system. CIP degradation intermediates were also identified and the pathways were proposed. This study suggested a new approach for catalytic degradation of CIP by ferrate.
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28916. 题目: A novel method for the separation of high-molecular-weight saturates from paraffinic petroleum based samples
文章编号: N18121005
期刊: Organic Geochemistry
作者: Petr Straka, Daniel Maxa, Martin Staš
更新时间: 2018-12-10
摘要: The precise chromatographic isolation of saturates is a common problem of the characterization of highly paraffinic petroleum based samples. Incomplete elution of high–molecular-weight saturates (HMWS) or contamination of saturates by aromatics can occur when alumina or silica gel are used to separate highly paraffinic samples. Here, we present a precise, fast and simple method for the quantitative isolation of HMWS from samples of highly paraffinic crude oils, crude oil deposits, high–boiling petroleum distillates, distillation residues and waxes. The method is based on a direct chromatographic elution of HMWS with n–heptane at 80 °C on a column packed with silica gel modified with silver nitrate. The pre–separation of asphaltenes from samples is not necessary. This allowed for a quantitative elution of all present HMWS (up to C100) with no contamination by aromatics. As an example of a practical application to benefit from this efficient hydrocarbon fractionation procedure, is the analysis of crude oils and deposits. A detailed knowledge of the content of high-molecular-weight n–alkanes in these samples can help to prevent problems during crude oil transport and storage.
28917. 题目: Response of bloom-forming cyanobacterium Microcystis aeruginosa to 17β-estradiol at different nitrogen levels
文章编号: N18121004
期刊: Chemosphere
作者: Leilei Bai, Chicheng Cao, Changhui Wang, Hui Zhang, Jiancai Deng, Helong Jiang
更新时间: 2018-12-10
摘要: Co-existence of cyanobacterial harmful algal blooms (CyanoHABs) and steroid estrogens (SEs) has been an increasing concern in eutrophic waters. The cellular responses and biodegradation of 17β-estradiol (E2) in cyanobacterium Microcystis aeruginosa were investigated at different nitrogen levels. During the 10-d experiment, the growth of M. aeruginosa was stimulated by 10–100 μg L−1 of E2 at the lowest nitrogen level of 0.5 mg L−1, whereas the presence of E2 inhibited the cyanobacterial growth at 5 mg L−1 of nitrogen. With nitrogen concentration increased to 50 mg L−1, the impact of E2 on levels of growth rate and chlorophyll a (Chla) alleviated. Exposure to E2 also promoted the superoxide dismutase activity of M. aeruginosa, coupled with cellular oxidative damage as indicated by the increasing malondialdehyde content. A sufficient nitrogen supply mitigated the oxidative stress of E2 through enhancing the synthesis of detoxification-related enzymes. Simultaneously, the secretion of tryptophan-like substances in loosely- and tightly-bound extracellular polymeric substances was triggered for adapting to an E2 addition in the short term. Moreover, significant biodegradation of E2 was observed, and the process followed a first-order kinetic reaction. The obtained half-lives decreased with nitrogen levels and ranged from 2.47 to 2.81 and 3.39–5.04 d, respectively, at 10 and 100 μg L−1 of E2. These results provide a better understanding of the potential effects of SEs on CyanoHABs formation, as well as the important role of CyanoHABs on SEs removal in aquatic ecosystems, which should be fully considered in the control of combined pollution.
28918. 题目: Degradation of climbazole by UV/chlorine process: Kinetics, transformation pathway and toxicity evaluation
文章编号: N18121003
期刊: Chemosphere
作者: Wen-Wen Cai, Tao Peng, Jin-Na Zhang, Li-Xin Hu, Bin Yang, Yuan-Yuan Yang, Jun Chen, Guang-Guo Ying
更新时间: 2018-12-10
摘要: Climbazole is an antifungal agent widely used in household personal care products, and it was found persistent in chlorination disinfection process. Here we investigated the kinetics and mechanism of climbazole degradation by UV/chlorine process. The results showed that the UV/chlorine process dramatically enhanced degradation of climbazole when compared to the UV photolysis and chlorination alone. The neutral condition (pH 7) produced the highest reaction rate for the climbazole by UV/chlorine among the various pH conditions. Dissolved organic matter and inorganic ions in natural water showed moderate inhibition effects on the degradation of climbazole in the UV/chlorine process. Hydroxyl radical (OH and chlorine radical (Cl) were found to be the main reactive species in the degradation of climbazole, with the second-order rate constant of 1.24 × 1010 M−1 s−1 and 6.3 × 1010 M−1 s−1, respectively. In addition, the OH and Cl in the UV/chlorine at 100 μM accounted for 82.2% and 7.7% contributions to the removal of climbazole, respectively. Eleven of main transformation products of climbazole were identified in the UV/chlorine process. These oxidation products did not cause extra toxicity than climbazole itself. The findings from this study show that the combination of chlorination with UV photolysis could provide an effective approach for removal of climbazole during conventional disinfection process.
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28919. 题目: Micro(nano)plastics: An un-ignorable carbon source?
文章编号: N18121002
期刊: Science of The Total Environment
作者: Duofei Hu, Maocai Shen, Yaxin Zhang, Guangming Zeng
更新时间: 2018-12-10
摘要: Micro(nano)plastics, new emerging contaminants, are widely found in the environment due to continuous release. Massive and widespread presence of micro(nano)plastics may have a significant impact on the calculation of total organic carbon, and potentially result in misunderstanding of the overall environmental pollution level. Previous studies typically paid attention to the environmental distribution, source, analysis methods and technologies, as well as the environmental and ecological effects of micro(nano)plastics. However, little was aware of the total organic carbon consequences. There are few evidences for the contribution of micro(nano)plastics to total organic carbon. Accordingly, more efforts need to be taken to explore the contribution of micro(nano)plastics to total organic carbon.
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28920. 题目: Characterization of CDOM in saline and freshwater lakes across China using spectroscopic analysis
文章编号: N18121001
期刊: Water Research
作者: Kaishan Song, Yingxin Shang, Zhidan Wen, Pierre-Andre Jacinthe, Ge Liu, Lili Lyu, Chong Fang
更新时间: 2018-12-10
摘要: Colored dissolved organic matter (CDOM) is a major component of DOM in waters, and plays a vital role in carbon cycling in inland waters. In this study, the light absorption and three-dimensional excitation-emission matrix spectra (EEMs) of CDOM of 936 water samples collected in 2014–2017 from 234 lakes in five regions across China were examined to determine relationships between lake water sources (fresh versus saline) and their fluorescence/absorption characteristics. Results indicated significant differences regarding DOC concentration and aCDOM(254) between freshwater (6.68 mg C L−1, 19.55 m-1) and saline lakes (27.4 mg C L−1, 41.17 m-1). While humic-like (F5) and fulvic-like (F3) compounds contributed to CDOM fluorescence in all lake waters significantly, their contribution to total fluorescence intensity (FT) differed between saline and freshwater lakes. Significant negative relationships were also observed between lake altitude with either F5 (R2 = 0.63, N = 306) or FT (R2 = 0.64, N = 306), suggesting that the abundance of humic-like materials in CDOM tends to decrease with increased in lakes altitude. In high-altitude lakes, strong solar irradiance and UV exposure may have induced photo-oxidation reactions resulting in decreased abundance of humic-like substances and the formation of low molecular weight compounds. These findings have important implications regarding our understanding of C dynamics in lacustrine systems and the contribution of these ecosystems to the global C cycle.
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