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18641. 题目: Oriented acidification of wasted activated sludge (WAS) focused on odd-carbon volatile fatty acid (VFA): Regulation strategy and microbial community dynamics
文章编号: N18060904
期刊: Water Research
作者: Long Huang, Zhiqiang Chen, Dandan Xiong, Qinxue Wen, Ye Ji
更新时间: 2018-06-09
摘要: As the main intermediate metabolite in anaerobic digestion of wasted activated sludge (WAS), volatile fatty acids (VFAs) are proper substrate for mixed culture (MC) polyhydroxyalkanoate (PHA) synthesis. To further optimize the performance of MC PHA production process, VFA_odd (i.e., VFA with odd carbon atoms) oriented acidification process was proposed and conducted in this study. Three regulation factors including reaction pH, fraction of added β-cyclodextrin (β-CD) and glycerol were selected and response surface methodology (RSM) was used to enhance and effectively regulate the VFA_odd production while maintaining enough acidification degree in the WAS acidification. High percentage of VFA_odd (larger than 60% and dominated by propionic acid) can be obtained in the operating condition area with glycerol addition ratio (quantified by C/N) ranging from 15 to 20 and reaction pH ranging from 8.0 to 9.5 when β-CD addition was held at zero level (0.2 g/gTSS) according to the RSM. Semi-continuous acidification and MC PHA production assays further verified the reliability and effectiveness of the VFA_odd oriented acidification strategy. Microbial function group related to propionic acid production (Gprop) was defined based on the relationships between system function and microbial community structure, and 13 frequent species were found being involved in the Gprop. Roles of the group members in the oriented acidification were analyzed to understand the mechanisms of the regulation of VFA_odd production at microbial ecological level. A synergistic effect of WAS and glycerol on the VFA_odd production in the acidification process was revealed based on the ecological analysis.
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18642. 题目: Multiple linear regression models to predict the formation efficiency of triplet excited states of dissolved organic mat...
文章编号: N18060903
期刊: Limnology and Oceanography
作者: Andrew J. McCabe, William A. Arnold
更新时间: 2018-06-09
摘要: The source and composition of dissolved organic matter (DOM) dictates light absorption in surface waters. Sunlight absorption by chromophoric dissolved organic matter (CDOM) forms reactive intermediates and drives global organic carbon processing. Triplet excited states of CDOM (3CDOM*) are primary reactive intermediates formed by sunlight absorption by CDOM. 3CDOM* also produce secondary reactive intermediates, including radicals and reactive oxygen species, which are active in biogeochemical pathways. The efficiency of 3CDOM* formation (apparent quantum yield, AQYT) depends on DOM composition, especially DOM molecular weight. This dependence may arise from the greater probability of forming intra‐molecular charge‐transfer (CT) complexes in high‐molecular weight DOM that inhibit 3CDOM* formation. There are few examples that demonstrate this in field samples. In this report, vegetation, general hydrology, and watershed characteristics for 39 temperate wetlands, which are critical sources of high‐molecular weight DOM, from the United States were defined and related to DOM composition and AQYT. The DOM bulk composition was assessed using absorbance and fluorescence spectroscopies. AQYT was estimated under simulated sunlight using the probe 2,4,6‐trimethylphenol. Relatively high AQYT values (7%) were observed in wetlands with long hydroperiods and > 50% cropland watershed land cover compared to wetlands with >50% forest watershed land cover (< 1–4%). Low molecular weight DOM (E2/E3 > 7 and SUVA254 < 3 L mg‐C-1m-1) and autochthonous DOM (β/α > 0.7) had relatively high AQYT estimates ( 10%), indicating that allocthonous, high‐molecular weight compounds produce 3CDOM* less efficiently than autochthonous DOM. The CT theory of DOM light absorption and internal light‐screening offer mechanistic explanations for these trends.

18643. 题目: A comparative analysis for the development and recovery processes of different types of clogging in lab-scale vertical flow constructed wetlands
文章编号: N18060902
期刊: Environmental Science and Pollution Research
作者: Yongchao Zhou, Shan Luo, Bohai Yu, Tuqiao Zhang, Jin Li, Yiping Zhang
更新时间: 2018-06-09
摘要: Clogging is a major operational and maintenance issue associated with the use of constructed wetlands. In this study, four lab-scale vertical flow constructed wetlands (VFCW) were used to fully understand the development mechanisms of various types of clogging and their recovery characteristics. The VFCWs were fed with glucose solution, starch suspension with and without bacteriostat, glucose, and starch mixed solution, respectively, to simulate Bio-clogging, organic particle clogging (Op-clogging), inert particle clogging (Ip-clogging), and the combination of Bio-clogging and Op-clogging (C-clogging). Resting operations with water decline were applied to relieve the clogging in the VFCWs. The results indicate that Op-clogging occurred first, followed by C-clogging and Bio-clogging. Ip-clogging took the longest time to develop and did not occur by the end of this study. The microscope analysis found that the extracellular polymeric substances (EPS) bonded the starch particles together to form a dense membrane-like structure and promoted the clogging process. In addition, surface clogging was observed in all four experimental beds. Op-clogging occurred much closer to the surface than those caused by soluble organic matter and inert particles. Furthermore, the growth of biofilm caused significant decline in hydraulic conductivity, whereas its influence on porosity was relatively slight. Moreover, applying resting operation with water decline was effective for recovery from Bio-clogging, Op-clogging, and C-clogging in VFCWs except for Ip-clogging. The results also implied the recovery rates through applying resting operation with water decline were much higher than that with constant water level.

18644. 题目: A new look at the multi-G model for organic carbon degradation in surface marine sediments for coupled benthic–pelagic s...
文章编号: N18060901
期刊: Biogeosciences
作者: Konstantin Stolpovsky, Andrew W. Dale, and Klaus Wallmann
更新时间: 2018-06-09
摘要: The kinetics of particulate organic carbon (POC) mineralization in marine surface sediments is not well constrained. This creates considerable uncertainties when benthic processes are considered in global biogeochemical or Earth system circulation models to simulate climate–ocean interactions and biogeochemical tracer distributions in the ocean. In an attempt to improve our understanding of the rate and depth distribution of organic carbon mineralization in bioturbated (0–20 cm) sediments at the global scale, we parameterized a 1-D diagenetic model that simulates the mineralization of three discrete POC pools (a “multi-G” model). The rate constants of the three reactive classes (highly reactive, reactive, refractory) are fixed and determined to be 70, 0.5 and 0.001 yr-1, respectively, based on the Martin curve model for pelagic POC degradation. In contrast to previous approaches, however, the reactivity of the organic material degraded in the seafloor is continuous with, and set by, the apparent reactivity of material sinking through the water column. Despite the simplifications of describing POC remineralization using G-type approaches, the model is able to simulate a global database (185 stations) of benthic oxygen and nitrate fluxes across the sediment–water interface in addition to porewater oxygen and nitrate distributions and organic carbon burial efficiencies. It is further consistent with degradation experiments using fresh phytoplankton reported in a previous study. We propose that an important yet mostly overlooked consideration in upscaling approaches is the proportion of the reactive POC classes reaching the seafloor in addition to their reactivity. The approach presented is applicable to both steady-state and non-steady state scenarios, and links POC degradation kinetics in sedimentary environments to water depth and the POC rain rate to the seafloor.

18645. 题目: A uniform bacterial growth potential assay for different water types
文章编号: N18060807
期刊: Water Research
作者: Nadia Farhat, Frederik Hammes, Emmanuelle Prest, Johannes Vrouwenvelder
更新时间: 2018-06-08
摘要: The bacterial growth potential is important to understand and manage bacterial regrowth-related water quality concerns. Bacterial growth potential depends on growth promoting/limiting compounds, therefore, nutrient availability is the key factor governing bacterial growth potential. Selecting proper tools for bacterial growth measurement is essential for routine implementation of the growth potential measurement. This study proposes a growth potential assay that is universal and can be used for different water types and soil extract without restrictions of pure culture or cultivability of the bacterial strain. The proposed assay measures the sample bacterial growth potential by using the indigenous community as inocula. Flow cytometry (FCM) and adenosine tri-phosphate (ATP) were used to evaluate the growth potential of six different microbial communities indigenous to the sample being analyzed, with increasing carbon concentrations. Bottled mineral water, non-chlorinated tap water, seawater, river water, wastewater effluent and a soil organic carbon extract were analyzed. Results showed that indigenous bacterial communities followed normal batch growth kinetics when grown on naturally present organic carbon. Indigenous bacterial growth could detect spiked organic carbon concentrations as low as 10 μg/L. The indigenous community in all samples responded proportionally to the increase in acetate-carbon and proportional growth could be measured with both FCM and ATP. Bacterial growth was proportional to the carbon concentration but not the same proportion factor for the different water samples tested. The effect of inoculating the same water with different indigenous microbial communities on the growth potential was also examined. The FCM results showed that the highest increase in total bacterial cell concentration was obtained with bacteria indigenous to the water sample. The growth potential assay using indigenous bacterial community revealed consistent results of bacterial growth in all the different samples tested and therefore providing a fast, more stable, and accurate approach for monitoring the biological stability of waters compared to the previously developed assays. The growth potential assay can be used to aid in detecting growth limitations by compounds other than organic carbon.

18646. 题目: New insight into the mechanism of peroxymonosulfate activation by sulfur-containing minerals: Role of sulfur conversion in sulfate radical generation
文章编号: N18060806
期刊: Water Research
作者: Yang Zhou, Xiaolei Wang, Changyin Zhu, Dionysios D. Dionysiou, Guangchao Zhao, Guodong Fang, Dongmei Zhou
更新时间: 2018-06-08
摘要: Peroxymonosulfate (PMS) or persulfate activation by sulfur-containing minerals has been applied extensively for the degradation of contaminants; however, the role of sulfur conversion in this process has not been fully explored. In this study, pyrite (FeS2)-based PMS activation process was developed for diethyl phthalate (DEP) degradation, and its underlying mechanisms were elucidated. PMS was found to be efficiently activated by FeS2 for DEP degradation and mineralization, achieving 58.9% total organic carbon removal using 0.5 g/L FeS2 and 2.0 mM PMS. Sulfides were the dominant electron donor for PMS activation, and mediated Fe(II) regeneration to activate PMS on the surface of FeS2 particles. Meanwhile, different sulfur conversion intermediates, such as S5 2-, S8 0, S2O3 2-, and SO3 2-, were formed from the oxidation of sulfides by Fe(III) and PMS, and determined by X-ray photoelectron spectroscopy and in-situ attenuated total reflectance Fourier transform infrared spectroscopy analysis. SO3 2- was the dominant sulfur species responsible for sulfate radicals (SO4 -) generation by activating PMS directly or activating Fe(III) to initiate a radical chain reaction, which was supported by the electron paramagnetic resonance results. This study highlights the important role of sulfur conversion in PMS activation by pyrite and provides new insights into the mechanism of oxidant activation by sulfur-containing minerals.
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18647. 题目: Contrasting evolution of iron phase composition in soils exposed to redox fluctuations
文章编号: N18060805
期刊: Geochimica et Cosmochimica Acta
作者: Pauline Winkler, Klaus Kaiser, Aaron Thompson, Karsten Kalbitz, Sabine Fiedler, Reinhold Jahn
更新时间: 2018-06-08
摘要: Ferric iron (FeIII) solid phases serve many functions in soils and sediments, which include providing sorption sites for soil organic matter, nutrients, and pollutants. The reactivity of Fe solid phases depends on the mineral structure, including the overall crystallinity. In redox-active soils and sediments, repeated reductive dissolution with subsequent exposure to aqueous ferrous iron (Fe2+) and oxidative re-precipitation can alter Fe phase crystallinity and reactivity. However, the trajectory of Fe mineral transformation under redox fluctuations is unclear and has been reported to result in both increases and decreases in Fe phase crystallinity. Several factors such as water budget, organic matter input, redox dynamics as well as the initial Fe phase composition might play a role. The objective of our study was to examine if Fe minerals in soils that differ in porosity-dependent water leaching rate and initial Fe phase crystallinity, demonstrate distinct mineral transformations when subjected to redox fluctuations. We sampled paired plots of two soil types under similar management but with different water leaching rates and contrasting Fe oxide crystallinity — an Alisol rich in crystalline Fe phases and an Andosol rich in short-range-ordered (SRO) Fe phases. The two soils were either exposed to several decades of redox fluctuations during rice paddy cultivation (paddy) or to predominantly oxic conditions in neighboring vegetable gardens (non-paddy). Paddy soils are uniquely suited for this type of study because they are regularly submerged and develop regular redox fluctuations. We also incubated the non-paddy soils in the laboratory for one year through eight anoxic/oxic cycles and monitored the aqueous soil geochemistry. M ssbauer spectroscopy was then used to evaluate Fe mineral speciation in field soils (paddy and non-paddy) and laboratory incubations. In the field soils, we found that redox fluctuation had contrasting effects on Fe oxide crystallinity, with crystallinity being lower in the Alisol paddy soil and higher in the Andosol paddy soil than in their corresponding non-paddy controls. In the laboratory incubation experiment, Eh, pH and dissolved Fe2+ responded as anticipated, with elevated Fe2+ concentrations during the anoxic periods as well as low Eh and high pH. M ssbauer measurements suggest the fluctuating redox incubation was beginning to alter Fe oxide crystallinity along the same trajectory as observed in the field, but the changes were within the range of fitting errors. We propose that reductive dissolution of crystalline Fe oxides prevails in the soil rich in crystalline Fe oxides (Alisol) and that re-precipitation as SRO Fe oxides is favored by constrained leaching, which leads to the observed decrease in Fe oxide crystallinity. In the soil rich in SRO Fe phases (Andosol), preferential reductive dissolution of SRO Fe oxides coupled with stronger leaching of dissolved Fe2+ causes the observed relative increase in crystallinity of the remaining Fe oxides. The observed increase in Fe oxide crystallinity may further be a result of Fe(II)-catalyzed re-crystallization of SRO Fe oxides. These findings indicate that, besides other factors, the Fe mineral composition of the initial soil or sediment as well as the leaching rate likely influence the trajectory of Fe oxide evolution under alternating redox-conditions.

18648. 题目: Degradation mechanism of cyanide in water using a UV-LED/H2O2/Cu2+ system
文章编号: N18060804
期刊: Chemosphere
作者: Tae-Kyoung Kim, Taeyeon Kim, Areum Jo, Suhyun Park, Kyungho Choi, Kyung-Duk Zoh
更新时间: 2018-06-08
摘要: In this study, we developed a UV-LED/H2O2/Cu2+ system to remove cyanide, which is typically present in metal electroplating wastewater. The results showed the synergistic effects of UV-LED, H2O2, and Cu2+ ions on cyanide removal in comparison with UV-LED photolysis, H2O2 oxidation, UV-LED/H2O2, and H2O2/Cu2+ systems. Cyanide was removed completely in 30 min in the UV-LED/H2O2/Cu2+ system, and its loss followed pseudo-first order kinetics. Statistically, both H2O2 and Cu2+ ions showed positive effects on cyanide removal, but Cu2+ ions exhibited a greater effect. The highest cyanide removal rate constant (k = 0.179 min-1) was achieved at pH 11, but the lowest was achieved at pH 12.5 (k = 0.064 min-1) due to the hydrolysis of H2O2 (pKa of H2O2 = 11.75). The presence of dissolved organic matter (DOM) inhibited cyanide removal, and the removal rate constant exhibited a negative linear correlation with DOM (R 2 = 0.987). The removal rate of cyanide was enhanced by the addition of Zn2+ ions (from 0.179 to 0.457 min-1), while the co-existence of Ni2+ or Cr+6 ion with Cu2+ ion reduced cyanide removal. The formation of OH radicals in the UV-LED/H2O2/Cu2+ system was verified using an aminophenyl fluorescence (APF) probe. Cyanate ions and ammonia were detected as the byproducts of cyanide decomposition. Finally, an acute toxicity reduction of 64.6% was achieved in the system within 1 h, despite a high initial cyanide concentration (100 mg/L). In terms of removal efficiency and toxicity reduction, the UV-LED/H2O2/Cu2+ system may be an alternative method of cyanide removal from wastewaters.
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18649. 题目: Enhanced sorption of hexavalent chromium [Cr(VI)] from aqueous solutions by diluted sulfuric acid-assisted MgO-coated biochar composite
文章编号: N18060803
期刊: Chemosphere
作者: Ran Xiao, Jim J. Wang, Ronghua Li, Jonghwan Park, Yili Meng, Baoyue Zhou, Scott Pensky, Zengqiang Zhang
更新时间: 2018-06-08
摘要: Metal oxide-Carbon composites have aroused great interesting towards specific anionic contaminants removal from the polluted environment. In this study, aiming at removing toxic chromate ion [Cr(VI)] from aqueous solutions, a novel approach was developed to produce surface-enhanced MgO-coated biochar adsorbent from sugarcane harvest residue (SHR). It was found that sulfuric acid hydrolysis and MgO-coating both facilitated the removal of Cr(VI) by biochars, and the maximum sorption capacities for the pristine biochar (SHR550), MgO-coated biochar (MgSHR550), and acid-assisted MgO-coated biochar (MgASHR550) that derived from the Langmuir isotherm model were 20.79, 54.64, and 62.89 mg g-1, respectively. Additionally, the Cr(VI) removal was a pseudo-second-order kinetic model controlled process with equilibrium reached within 24 h. The mechanism investigation revealed that Cr(VI) ions was directly sorbed by the MgO-coated biochars via the chemical interaction between MgO and Cr(VI), whereas the sorption-coupled reduction of Cr(VI) to Cr(III) governed the sorption of Cr(VI) on the SHR550. Although the increases of solution pH (>2.0) and KNO3 concentration (>0.05 mol L-1) reduced the Cr(VI) removal by biochars, while there were lower secondary pollution risks in MgO-coated biochar treatments due to the suppressed release of Cr(III) in solutions. This work could provide guidance for the production of efficient biochar for the removal of Cr(VI) from wastewater.
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18650. 题目: Combining micelle-clay sorption to solar photo-Fenton processes for domestic wastewater treatment
文章编号: N18060802
期刊: Environmental Science and Pollution Research
作者: Monica Brienza, Shlomo Nir, Gael Plantard, Vincent Goetz, Serge Chiron
更新时间: 2018-06-08
摘要: A tertiary treatment of effluent from a biological domestic wastewater treatment plant was tested by combining filtration and solar photocatalysis. Adsorption was carried out by a sequence of two column filters, the first one filled with granular activated carbon (GAC) and the second one with granulated nano-composite of micelle-montmorillonite mixed with sand (20:100, w/w). The applied solar advanced oxidation process was homogeneous photo-Fenton photocatalysis using peroxymonosulfate (PMS) as oxidant agent. This combination of simple, robust, and low-cost technologies aimed to ensure water disinfection and emerging contaminants (ECs, mainly pharmaceuticals) removal. The filtration step showed good performances in removing dissolved organic matter and practically removing all bacteria such as Escherichia coli and Enterococcus faecalis from the secondary treated water. Solar advanced oxidation processes were efficient in elimination of trace levels of ECs. The final effluent presented an improved sanitary level with acceptable chemical and biological characteristics for irrigation.

18651. 题目: Humic substances in Fluvisols of the Lower Vistula floodplain, North Poland
文章编号: N18060801
期刊: Environmental Science and Pollution Research
作者: Magdalena Banach-Szott, Krystyna Kondratowicz-Maciejewska, Miros?aw Kobierski
更新时间: 2018-06-08
摘要: The present study describes properties of humic substances of the Fluvisols (the Lower Vistula, Poland). Fluvisols under agricultural management (arable soil and grassland) were sampled from the surface horizon 50, 200, 600, and 900 m from the Vistula River. The content of carbon in the fractions of humic acids (CHAs), fulvic acids (CFAs), and humins (CHUMIN) as well as the content of dissolved organic carbon (DOC) were assayed. The organic matter of the soils that were sampled 200 m from the river demonstrated a lowest share of the humic acids (HAs) and fulvic acids (FAs). The percentage share of the hydrophilic fractions (HIL) in the HAs and, as a result the value of the HIL/ΣHOB ratio, increased with the distance from the riverbed. The HAs of the soils located further from the riverbed had a higher degree of humification compared to the HAs of the soils that were sampled 50 and 200 m away. Based on the research results, it was determined that the properties of HAs can be used to evaluate the effect of flood events, their location, and scope on the transformation of the organic matter in fluvial sediments.

18652. 题目: Use of palmitoleic acid and its oxidation products for monitoring the degradation of ice algae in Arctic waters and bottom sediments
文章编号: N18060705
期刊: Organic Geochemistry
作者: Jean-Fran?ois Rontani, Rémi Amiraux, Catherine Lalande, Marcel Babin, Hak-Ryul Kim, Simon T. Belt
更新时间: 2018-06-07
摘要: Degradation of palmitoleic acid (C16:1ω7), the main fatty acid component of sea ice-associated (sympagic) diatoms, was monitored in Arctic sea ice at the beginning of ice melting and in the underlying sinking particles and superficial bottom sediments. In sea ice, degradation of sympagic algae involved biotic oxidation induced by 10S-DOX-like lipoxygenase of unknown salinity-stressed attached bacteria, while photo- and autoxidation were limited. In the water column, strong hydratase and Z/E isomerase activity were observed. Hydration of unsaturated fatty acids seems to be a detoxification strategy, which is essential for bacterial survival when associated with free fatty acid-rich environments such as ice algae. In contrast, Z/E isomerisation of palmitoleic acid was attributed to the release of Fe2+ ions during radical-induced damage of the active site of the bacterial 10S-DOX-like lipoxygenase and Z/E isomerases. Due to the poor physiological state of their attached bacteria resulting from salinity stress in brine channels or toxicity of free ice algae fatty acids, sympagic algae appeared to be only very weakly biotically degraded within the water column. In bottom sediments, free radicals resulting from 10S-DOX-like lipoxygenase activity induced a strong autoxidation of the ice algal material. The presence in bottom sediments of a significant proportion of oxidation products resulting from 10S-DOX-like lipoxygenase activity attested to the strong contribution of sea ice-derived OM released during the early stages of ice melt prior to deposition in the sediments. However, on the basis of the highest fatty acid photooxidation state observed in these sediments, an additional contribution of highly photooxidized material (ice algal material released at the end of ice melting or open water phytoplankton) seems likely. The degradation of hydroperoxides, resulting from biotic and abiotic degradation of palmitoleic acid, appeared to involve: (i) homolytic cleavage of the peroxyl group affording the corresponding hydroxy- and oxoacids, (ii) reduction to the corresponding hydroxyacids by peroxygenases, (iii) heterolytic proton-catalysed cleavage and (iv) conversion to allylic 1,4-diols by diol synthases and hydroperoxide isomerases.

18653. 题目: Enhancement of surfactant biodegradation with an anaerobic membrane bioreactor by introducing microaeration
文章编号: N18060704
期刊: Chemosphere
作者: Zhenmin Cheng, Yuansong Wei, Qingqing Zhang, Junya Zhang, Tiedong Lu, Yuanmei Pei
更新时间: 2018-06-07
摘要: In controlled ecological life support system (CELSS), 100% water recycle efficiency is needed. Both water and nutrients in wastewater needs reclaiming. In an anaerobic membrane bioreactor (AnMBR) designed to hydrolyze organic matters and convert organic nitrogen, accumulation of anionic surfactants and organic compounds was observed in the supernatant. To solve the problem, microaeration which had rarely been reported to enhance surfactants biodegradation in anaerobic process was introduced and it was proved to be an effective approach that resulted in concentrations of surfactants and soluble chemical oxygen demand (SCOD) in the supernatant decreasing from 9000 mg/L and 40000 mg/L to 2000 mg/L and 10000 mg/L, respectively. And the degradations followed the kinetic characteristics of zero order reaction with R2 values of 0.9472 and 0.949. Three-dimensional excitation emission matrix (3D-EEM) analysis revealed that some activities of microbes were activated and enhanced by microaeration, which resulted in the disintegration of aggregates of large molecules, indicated by the size exclusion chromatography (SEC). After the introduction of microaeration, the emerging genera Aquamicrobium, Flaviflexus, Pseudomonas and Thiopseudomonas in the microbial community might be responsible for the effective biodegradation of the surfactants.

18654. 题目: Photocatalytic degradation of organic pollutants in wastewater with g-C3N4/sulfite system under visible light irradiation
文章编号: N18060703
期刊: Chemosphere
作者: Yi Wei, Qiancheng Zou, Peng Ye, Manye Wang, Xiaoxia Li, Aihua Xu
更新时间: 2018-06-07
摘要: To develop low cost and high efficient sulfate radical (SO4 -) based advanced oxidation processes (AOPs) for rapid remediation of contaminated waters is of great interest. In this study, a green and novel SO4 - based AOPs, in situ visible light activation of sulfite by graphitic carbon nitride (g-C3N4), for the degradation of organic pollutants is reported. The g-C3N4+HSO3 -+ Vis system could achieve remarkably enhanced degradation of organic pollutants such as organic dyes and phenol in aqueous solution. The excellent reusability of the metal free catalyst was also observed during ten successive cycles. The efficiency of the system was dependent on the reaction conditions, which first increased and then decreased with the increase of HSO3 - concentration and initial solution pH. The addition of HCO3 - stimulated the pollutant degradation, but other water matrix components such as Cl and humic acid showed nearly no influence on the reaction. The mechanism investigations suggested that sulfite is oxidized in the system to sulfite radicals, which then react with dioxygen and superoxide radicals to form SO5 - radicals and HSO5 - respectively. SO5 - radicals can be also reduced by sulfite or photoelectron to HSO5 -. SO4 - radicals were then produced from HSO5 -reduction by photoelectron, and contributed to dye degradation in the system together with superoxide radicals. This study provides a novel new approach for efficient degradation of organic degradation via sulfite activation.
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18655. 题目: Effect of aquatic macrophyte growth on landscape water quality improvement
文章编号: N18060702
期刊: Environmental Science and Pollution Research
作者: Hengfeng Zhang, Yixi Zhao, Hang Yin, Yuanyuan Wang, Huixian Li, Zhanshen Wang, Yongbo Geng, Wenyan Liang, Hongjie Wang
更新时间: 2018-06-07
摘要: The water of urban landscape park is often confronted with microalgal blooms due to its stagnancy. Bioremediation using the combined emergent and submerged plants to control the microalgae growth was investigated in the present study. Two water bodies (Bei and Xin) of Yuyuantan Park in Beijing were selected for the field experiments, and the other lakes with different vegetation of macrophytes were selected as the comparison. The concentrations of chlorophyll a (chl a), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP), and water temperature and transparency were monitored before and after bioremediation from 2015 to 2017. Results showed that the effects of microalgal inhibition were more significant 2 years after bioremediation. Specifically, the chl a of Dong Lake without any vegetation of macrophytes was up to 65.1 μg/L in summer of 2017, while the Bei and Xin Lakes was only 6.2 and 11.3 μg/L, respectively. In addition, the water quality and transparency also improved, with water bodies being crystal clear. Submerged plants played major roles in microalgal control and water quality improvement, compared to the lakes with only emergent plants. The intensity of humic acid-like substances in three-dimensional fluorescent spectra was stronger for the lakes with submerged plants.

18656. 题目: A simple cleanup method for the removal of humic substances from soil protein extracts using aluminum coagulation
文章编号: N18060701
期刊: Environmental Science and Pollution Research
作者: Manolis Mandalakis, Nicolai S. Panikov, Paraskevi N. Polymenakou, Maria V. Sizova, Aristeidis Stamatakis
更新时间: 2018-06-07
摘要: Soil proteomics, the large-scale characterization of the entire protein complement in soils, provides a promising approach for deciphering the role of microbial functioning in terrestrial ecosystems. However, the extraction of soil proteins in sufficient quantities and of adequate purity remains a challenging task mainly due to the co-extraction of interfering humic substances. Up to now, the treatment of soil extracts with liquid phenol has been the “gold standard” for reducing humics, while the NoviPure cleanup kit was recently launched as a non-toxic approach. The present study describes an alternative method for delivering high-purity proteins based on humic coagulation with trivalent aluminum ions (Al3+). Various experimental parameters were optimized individually in order to maximize protein yield and diminish co-extracted humics. The optimized method was applied on a set of soil samples with diverse physicochemical characteristics and a comparison with the other two techniques was conducted. The amount of residual humics resulting from Al3+-based method was 26 and 35% higher than that from phenol treatment and NoviPure Kit, respectively, but these differences were of marginal statistical significance. With regard to extracted proteins, the average yields of the three methods were comparable, without showing any statistically significant differences. Overall, humic coagulation with Al3+ offers comparable cleanup performance in terms of protein yield and purity, but it is less toxic and less complex than the phenol-partitioning method, whereas it is far less expensive than the NoviPure Kit. The new technique is expected to facilitate the implementation of proteomic studies in soils.

18657. 题目: Characteristics of wet dissolved carbon deposition in a semi-arid catchment at the Loess Plateau, China
文章编号: N18060603
期刊: Biogeosciences
作者: Linhua Wang, Haw Yen, Liding Chen, Xinhui E, and Yafeng Wang
更新时间: 2018-06-06
摘要: Wet dissolved carbon deposition is a critical node of the global carbon cycle, but little is known about dissolved organic and inorganic carbon (DOC and DIC) concentrations and fluxes in the semi-arid areas of the Loess Plateau Region (LPR). In this study, we measured variations in DOC and DIC concentrations in rainfalls at Yangjuangou Ecological Restoration and Soil and Water Observatory. Rainwater samples were collected in 16 rainfall events from July to September and the event-based, monthly concentrations and fluxes of DOC and DIC were quantified. The results showed that the event-based concentrations and fluxes of DOC and DIC were highly variable, ranging from 0.56 to 28.71 mg C L-1 and from 3.47 to 17.49 mg C L-1, respectively. The corresponding event-based fluxes ranged from 0.21–258.36 mg C m-2 and from 4.12 to 42.32 mg C m-2. The monthly concentrations of DOC and DIC were 24.62 and 4.30 (July), 3.58 and 10.52 (August), and 1.01 and 5.89 (September) mg C L-1, respectively. Thus, the monthly deposition fluxes of DOC and DIC were 541.64/94.60, 131.03/385.03, and 44.44/259.16 mg C m-2 for July, August, and September, respectively. In addition, the concentrations of DOC and DIC for the concentrated rainfall season (July–September) in the studied catchment were 7.06 and 7.00 mg C L-1, respectively. The estimated annual wet dissolved carbon depositions were 1.91 and 1.89 g C m-2 yr-1 for DOC and DIC, respectively. The results of this study suggest the variation in concentrations and fluxes of DOC and DIC and explore that these variation may be related to the dissolved carbon source and the rainfall characteristics during the concentrated rainfall season in the semi-arid catchment of the LPR. Furthermore, these results also suggest that dissolved carbon may be an important external input of carbon into terrestrial ecosystems.

18658. 题目: Effects of vegetation and fecal pellets on the erodibility of cohesive sediments: Ganghwa tidal flat, west coast of Korea
文章编号: N18060602
期刊: Environmental Pollution
作者: Ho Kyung Ha, Hun Jun Ha, Jun Young Seo, Sun Min Choi
更新时间: 2018-06-06
摘要: Although the Korean tidal flats in the Yellow Sea have been highlighted as a typical macrotidal system, so far, there have been no measurements of the sediment erodibility and critical shear stress for erosion (τ ce ). Using the Gust erosion microcosm system, a series of field experiments has been conducted in the Ganghwa tidal flat to investigate quantitatively the effects of biogenic materials on the erodibility of intertidal cohesive sediments. Four representative sediment cores with different surficial conditions were analyzed to estimate the τ ce and eroded mass. Results show that τ ce of the “free” sediment bed not covered by any biogenic material on the Ganghwa tidal flat was in the range of 0.1–0.2 Pa, whereas the sediment bed partially covered by vegetation (Phragmites communis) or fecal pellets had enhanced τ ce up to 0.45–0.6 Pa. The physical presence of vegetation or fecal pellets contributed to protection of the sediment bed by blocking the turbulent energy. An inverse relationship between the organic matter included in the eroded mass and the applied shear stress was observed. This suggests that the organic matter enriched in a near-bed fluff layer is highly erodible, and the organic matter within the underlying sediment layer becomes depleted and less erodible with depth. Our study underlines the role of biogenic material in stabilizing the benthic sediment bed in the intertidal zone.
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18659. 题目: Revegetation of the riparian zone of the Three Gorges Dam Reservoir leads to increased soil bacterial diversity
文章编号: N18060601
期刊: Environmental Science and Pollution Research
作者: Qingshui Ren, Changxiao Li, Wenhang Yang, Hong Song, Peng Ma, Chaoying Wang, Rebecca L. Schneider, Stephen J. Morreale
更新时间: 2018-06-06
摘要: As one of the most active components in soil, bacteria can affect soil physicochemical properties, its biological characteristics, and even its quality and health. We characterized dynamics of the soil bacterial diversity in planted (with Taxodium distichum) and unplanted soil in the riparian zone of the Three Gorges Dam Reservoir (TGDR), in southwestern China, in order to accurately quantify the changes in long-term soil bacterial community structure after revegetation. Measurements were taken annually in situ in the TGDR over the course of 5 years, from 2012 to 2016. Soil chemical properties and bacterial diversity were analyzed in both the planted and unplanted soil. After revegetation, the soil chemical properties in planted soil were significantly different than in unplanted soil. The effects of treatment, time, and the interaction of both time and treatment had significant impacts on most diversity indices. Specifically, the bacterial community diversity indices in planted soil were significantly higher and more stable than that in unplanted soil. The correlation analyses indicated that the diversity indices correlated with the pH value, organic matter, and soil available nutrients. After revegetation in the riparian zone of the TGDR, the soil quality and health is closely related to the observed bacterial diversity, and a higher bacterial diversity avails the maintenance of soil functionality. Thus, more reforestation should be carried out in the riparian zone of the TGDR, so as to effectively mitigate the negative ecological impacts of the dam. Vegetating the reservoir banks with Taxodium distichum proved successful, but planting mixed stands of native tree species could promote even higher riparian soil biodiversity and improved levels of ecosystem functioning within the TGDR.

18660. 题目: Chemometric tool to study the mechanism of arsenic contamination in groundwater of Puducherry region, South East coast of India
文章编号: N18060512
期刊: Chemosphere
作者: M. Sridharan, D. Senthil Nathan
更新时间: 2018-06-05
摘要: To understand occurrence, distribution and source of arsenic, 175 groundwater samples from coastal aquifers of the Puducherry region were collected and analyzed for major ions and trace metals. The concentration of As in groundwater of study area ranges from not detectable — 28.88 μg/L during the post-monsoon and not detectable — 36.88 μg/L in the pre-monsoon. The desirable limit for As in groundwater is 10 μg/L as per World Health Organization and Bureau of Indian standard. About 13.64 and 11.50% of groundwater samples shows arsenic concentration higher than recommended limit. Hydrochemical facies which dominate during pre and post monsoon are Na-K-Cl-SO4, Ca-Cl and Ca-Mg-Cl-SO4type and Na-K-Cl-SO4, mixedCa-Na-HCO3, Ca-HCO3 and mixed Ca-Mg-Cl type respectively. The Gibbs diagram suggested that rock-water interaction is major process controlling hydrochemistry of groundwater. From the Pourbaix diagram, it is inferred that H3AsO3 is the principal As species in groundwater. The PHREEQC modelling indicates supersaturation of ferric oxides and hydroxide mineral phases in aquifer system which on reductive dissolution releases arsenic into groundwater. Statistical analysis (Spearman Correlation and Principal Component Analysis) showed that reductive dissolution of As-bearing minerals and Fe-oxyhydroxides in the presence of organic matter is the major process contributing arsenic into groundwater. The relationship between As, K+ and HCO 3 indicates agricultural and competitive exchange process which is an additional contributor of arsenic in groundwater. The sources which act as a sink and responsible for the release of As into the groundwater are marine sediments enriched in As and Fe-bearing minerals and organic matter.
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