论文检索

主页 | efc软件 | 课题库 | 公众号
:



总访问量:344813

总访客量:20044

关键词:
Organic Matter |
DOM |
POM |
Soil OM |
Sediment OM |
Organic Carbon |
Organic Nitrogen |
Biomarker |
Humic Substances |
Fulvic Substances |
Humins |
Biochar |
Black Carbon |
GDGT |
Lignin |
Free Radical |
...
最新文章  | 
昨日文章 | 
前日文章
期刊:
Agriculture, Ecosystems & Environment |
Agricultural Water Management |
Applied Geochemistry |
Applied Soil Ecology |
Aquatic Geochemistry |
Atmospheric Research |
Biogeochemistry |
Biogeosciences |
Biology and Fertility of Soils |
Bioresource Technology |
CATENA |
Chemical Engineering Journal |
Chemical Geology |
Chemosphere |
CLEAN - Soil, Air, Water |
Colloids and Surfaces A: Physicochemical and Engineering Aspects |
Deep Sea Research Part II: Topical Studies in Oceanography |
Earth-Science Reviews |
Ecological Engineering |
Ecology Letters |
Ecology |
Ecotoxicology and Environmental Safety |
Environment International |
Environmental Earth Sciences |
Environmental Geochemistry and Health |
Environmental Monitoring and Assessment |
Environmental Pollution |
Environmental Research |
Environmental Science & Technology |
Environmental Science and Pollution Research |
Environmental Science: Processes Impacts |
Environmental Science: Water Research & Technology |
Environmental Toxicology and Chemistry |
Estuarine, Coastal and Shelf Science |
European Journal of Soil Science |
Forest Ecology and Management |
Geochimica et Cosmochimica Acta |
Geoderma |
Geophysical Research Letters |
Global Change Biology |
Global Biogeochemical Cycles |
Groundwater |
Harmful Algae |
International Journal of Coal Geology |
Journal of Environmental Chemical Engineering |
Journal of Environmental Management |
Journal of Environmental Sciences |
Journal of Geophysical Research: Biogeosciences |
Journal of Geophysical Research: Oceans |
Journal of Hazardous Materials |
Journal of Membrane Science |
Journal of Soils and Sediments |
Land Degradation & Development |
Limnology and Oceanography |
Marine Chemistry |
Marine Pollution Bulletin |
Nature Communications |
Nature Geoscience |
Ocean Science Journal |
Oikos |
Organic Geochemistry |
Palaeogeography, Palaeoclimatology, Palaeoecology |
Plant and Soil |
Progress in Oceanography |
Quaternary International |
Science of The Total Environment |
Sedimentary Geology |
Separation and Purification Technology |
Soil and Tillage Research |
Soil Biology and Biochemistry |
Waste Management |
Water Research |
Water, Air, & Soil Pollution |
Wetlands |
...

所有论文

61. 题目: Contrasting temperature responses of soil respiration derived from soil organic matter and added plant litter
文章编号: N20070402
期刊: Biogeochemistry
作者: Jasmine M. Robinson, Shaun L. L. Barker, Vickery L. Arcus, Samuel R. McNally, Louis A. Schipper
更新时间: 2020-07-04
摘要: Accurate description of temperature response and sensitivity of different carbon pools within soil is critical for accurately modelling soil carbon stocks and changes. Inconsistent sampling, incubation and fractionation methods highlights the need for new approaches to this area of study. We developed and tested a new protocol which allowed measurement of the temperature response of two carbon pools within soil. A Horotiu silt loam soil, wet up to 60% maximum water holding capacity, was mixed with 13C-enriched plant litter and incubated for 5 or 20 h, at 30 discrete temperatures (~ 2–50 °C). A mixing model was used to separate respired CO2 into litter and soil organic matter sourced carbon pools, which were then fitted using macromolecular rate theory. Overall, litter sourced respiration had a low Topt (the temperature where respiration rate is maximal) and was less temperature sensitive (Q10) than soil organic matter sourced respiration, which was more Arrhenius-like. We attribute these differences in temperature parameters to the factors that control the availability of carbon to microbes from the labile litter (enzyme kinetics with a clear temperature optimum) compared to the relatively stable soil organic matter (desorption and diffusion that exhibit Arrhenius behaviour). The developed method is rapid and reliable and may be suited to exploring temperature response of a variety of 13C-labelled pools in soil and more clearly demonstrates that labile carbon has very different temperature response than more stable carbon pools in soil.

62. 题目: Aquatic testing guidelines insufficiently control the influence of dilution water toc and hardness on cationic polymer toxicity – A proposal to improve standardized test procedures
文章编号: N20070401
期刊: Chemosphere
作者: Edward R. Salinas, Jared S. Bozich, Sara Kolbenschlag, Miriam Kary-Heinrich, Philipp W. Hopp, Rüdiger Lukas, Sabine Zok, Björn Hidding
更新时间: 2020-07-04
摘要:

Cationic polymers (CPs) are widely used chemicals for wastewater treatment applications and in various down-the-drain household products. The aquatic toxicity of CPs results from an electrostatic interaction with negatively charged cell surfaces. These effects are greatly mitigated by the binding affinity of CPs to total organic carbon (TOC) in surface water. Consequently, baseline aquatic toxicity tests of CPs using clean lab water (TOC < 2 mg/L) typically overestimate toxicity and risk which is greatly mitigated at higher environmentally relevant OC levels. However, the point at which mitigation begins is not well defined and low-level TOC in lab water may influence the baseline toxicity outcome. Similarly, divalent cations, quantified as water hardness, may modulate the electrostatic binding between OC and CP. Although standard guidelines define limits for lab water hardness and TOC, the consequences of variability within those limits on test outcome is unknown. We investigated the impact of part-per-billion (ppb) additions of TOC to lab water at different hardness levels on CP acute toxicity to Daphnia magna and Raphidocelis subcapitata. In both species, the acute toxicities of CPs with different molecular weight and charge density varied by > 10-fold in response to slight changes in TOC and water hardness, although parameters were maintained within guideline limits. When determining the baseline aquatic toxicity of CPs, the lab water should be standardized at the lowest biologically tolerable hardness and TOC at a reliably measurable level (>1 - < 2 mg/L) to reduce variability and increase the reliability of the toxicity estimate.

63. 题目: Saline-alkali soil applied with vermicompost and humic acid fertilizer improved macroaggregate microstructure to enhance salt leaching and inhibit nitrogen losses
文章编号: N20070312
期刊: Applied Soil Ecology
作者: Mengli Liu, Chong Wang, Xuelian Liu, Yuchen Lu, Yifan Wang
更新时间: 2020-07-03
摘要:

High salinity, poor soil structure and nutrient deficiencies are the main limitations in saline-alkali soils. We investigated the effects on the microstructure, and the aerobic and anaerobic bacterial communities in the macroaggregates following addition of vermicompost and humic acid fertilizer to saline-alkali soil. These effects could enhance salt leaching and inhibit nitrogen losses in the topsoil. Vermicompost and humic acid fertilizer improved soil aggregate stability and the microstructure of macroaggregates (porosity, path tortuosity and effective porosity), which in turn increased soil permeability and salt leaching in saline-alkali topsoil. The improvement in aggregate microstructure affected the soil bacterial community of the macroaggregates by increasing the relative abundances of aerobic heterotrophs, such as Chloroflexi and Bacteroidetes. Additionally, vermicompost and humic acid fertilizer influenced nitrogen cycling by the macroaggregate microbial community, and stimulated nitrification by increasing archaeal and bacterial amoA gene copy numbers in the topsoil, but inhibited nitrite-reducing bacteria by decreasing nirS and nirK gene copy numbers. Furthermore, these amendments increased microbial N2O reduction by increasing nosZ gene copy numbers, suggesting that vermicompost and humic acid fertilizer have the potential to reduce N2O emissions in saline-alkali soil. In summary, vermicompost and humic acid fertilizer can ameliorate saline-alkali soils by replenishing organic matter, improving aggregate microstructure, and regulating the microbial community, which could increase salt leaching and inhibit nitrogen losses.

64. 题目: Impact of algal organic matter on the performance, cyanotoxin removal, and biofilms of biologically-active filtration systems
文章编号: N20070311
期刊: Water Research
作者: Youchul Jeon, Lei Li, Jose Calvillo, Hodon Ryu, Jorge W. Santo Domingo, Onekyun Choi, Jess Brown, Youngwoo Seo
更新时间: 2020-07-03
摘要:

The occurrence of harmful algal blooms dominated by toxic cyanobacteria has induced continuous loadings of algal organic matter (AOM) and toxins in drinking water treatment plants. However, the impact of AOM on the active biofilms and microbial community structures of biologically-active filtration (BAF), which directly affects the contaminant removal, is not well understood. In this study, we systematically examined the effects of AOM on BAF performance and bacterial biofilm formation over 240 days, tracing the removal of specific AOM components, a cyanotoxin [microcystin-LR (MC-LR)], and microbial community responses. The component analysis (excitation and emission matrix analysis) results for AOM revealed that terrestrial humic-like substances showed the highest removal among all the identified components and were strongly correlated to MC-LR removal. In addition, reduced empty bed contact time and deactivation of biofilms significantly decreased BAF performances for both AOM and MC-LR. The active biofilm, bacterial community structure, and mlrA gene (involved in microcystin degradation) abundance demonstrated that bacterial biofilm composition responded to AOM and MC-LR, in which Rhodocyclaceae, Saprospiraceae, and Comamonadaceae were dominant. In addition, MC-LR biodegradation appeared to be more active at the top than at the bottom layer in BAF. Overall, this study provides deeper insights into the role of biofilms and filter operation on the fate of AOM and MC-LR in BAF.

65. 题目: Conifers are a major source of sedimentary leaf wax n-alkanes when dominant in the landscape: Case studies from the Paleogene
文章编号: N20070310
期刊: Organic Geochemistry
作者: Kristen M. Schlanser, Aaron F. Diefendorf, Christopher K. West, David R. Greenwood, James F. Basinger, Herbert W. Meyer, Alexander J. Lowe, Hans H. Naake
更新时间: 2020-07-03
摘要:

Plant wax n-alkanes are valuable paleoclimate proxies because their carbon (δ13C) and hydrogen (δ2H) isotopes track biological and environmental processes. Angiosperms produce higher concentrations of n-alkanes than conifers, with some exceptions. Vegetation source is significant because in similar climates, both taxa produce n-alkanes with unique δ13C and δ2H values due to different physiological strategies. To test whether conifers contribute significantly to sediment n-alkanes and result in distinctive isotopic signatures, we collected sediment samples from a suite of Paleogene paleobotanical sites in North America with high and low conifer abundances. To disentangle the source of sediment n-alkanes, we measured the δ13C values of nonsteroidal triterpenoids (angiosperm biomarkers) and tricyclic diterpenoids (conifer biomarkers) to determine angiosperm and conifer end member δ13C values. We then compared these end member values to n-alkane δ13C values for each site to estimate their major taxon sources. At sites dominated by conifer macrofossils, δ13C values of n-alkanes indicate a conifer source. At mixed conifer and angiosperm sites, conifer contributions increased with increasing n-alkane chain length. At sites where conifers were not as abundant as angiosperms, the δ13C values of n-alkanes indicate a predominant angiosperm source with some sites showing a conifer contribution to n-C33 and n-C35 alkanes. This suggests that conifers in the Paleogene contributed to longer chain n-alkanes (n-C33 and n-C35) even when not the dominant taxa, but this likely differs for other geographic locations and taxa. This new approach allows unique floral information to be extracted when chain length is carefully considered in the absence of other paleobotanical data and necessitates having some paleovegetation constraints when interpreting carbon and hydrogen isotopes of plant wax-derived n-alkanes.

66. 题目: Phosphorus limitation affects the molecular composition of Thalassiosira weissflogii leading to increased biogenic silica dissolution and high degradation rates of cellular carbohydrates
文章编号: N20070309
期刊: Organic Geochemistry
作者: Christos Panagiotopoulos, Madeleine Goutx, Maxime Suroy, Brivaela Moriceau
更新时间: 2020-07-03
摘要:

Diatoms in general, and Thalassiosira weissflogii (T. weissflogii) in particular, are among the most ubiquitous phytoplanktonic species while, phosphorus (P) is an essential nutrient that limits productivity in many oceanic regimes. To investigate how T. weissflogii cultures grown under different P regimes are chemically altered before and during their prokaryotic degradation, T. weissflogii cells were cultivated under two

contrasting P conditions, P-stress and P-replete. Biodegradation experiments were conducted in natural sea water comprising a natural prokaryotic community. The particulate fraction was monitored for 3 weeks for organic carbon (POC), nitrogen (PON), biogenic silica (bSiO2), total carbohydrates (PCHO) and individual monosaccharides, including prokaryotic counting. Our results indicated that P-stress induced changes in the chemical composition of the T. weissflogii cells, causing a decrease to the Si/N (1.1 to 0.46) and Si/C (0.17 to 0.08) ratios. The P-stress T. weissflogii cells were characterized by high amounts of galactose (23% of PCHO), xylose (21%), and glucose (19%) compared to the P-replete T. weissflogii cells, which were dominated by ribose (20% of PCHO), further indicating the exhaustion of ribose-rich molecules (e.g., ATP) in T. weissflogii under P-stress conditions. The degradation experiments showed that bSiO2 produced under P-stress conditions dissolved more rapidly than bSiO2 formed under P-replete conditions, whereas POC and PON exhibited higher degradation rate constants in the P-replete T. weissflogii than in the P-stress T. weissflogii experiment. Overall, these observations show that T. weissflogii submitted to P-limitation, results in changes in its initial biochemical composition, increases frustule dissolution rate, and decreases the degradation of T. weissflogii-organic matter by marine prokaryotes.

67. 题目: Dissolved organic matter dynamics in the pristine Krka River estuary (Croatia)
文章编号: N20070308
期刊: Marine Chemistry
作者: Saša Marcinek, Chiara Santinelli, Ana-Marija Cindrić, Valtere Evangelista, Margherita Gonnelli, Nicolas Layglon, Stephane Mounier, Veronique Lenoble, Dario Omanović
更新时间: 2020-07-03
摘要:

The karstic Krka River is characterized by having lower dissolved organic carbon (DOC) concentrations (~30 μM) than coastal seawater (~60 μM). This peculiarity, together with the pristine nature of this area, makes the Krka River estuary a natural laboratory where it is possible to discriminate among the different dissolved organic matter (DOM) sources (riverine, marine and produced in-situ) and to study the main processes of DOM production and removal. The hypothesis behind this work is that in winter, due to the high discharge of the river, most of the DOM has a terrestrial signature, whereas in summer autochthonous DOM compose the main fraction of the DOM pool because of the reduced discharge, the high temperature and primary production. Our data shows that DOM in the river mainly consists of terrestrial molecules, as suggested by the high chromophoric content and low spectral slope (S275–295) values, as well by the predominance of humic-like substances. DOM in the seawater features the concentration and optical properties of the typical marine DOM from open sea waters. In summer, low riverine discharge and high temperature promote the intense biological activity, with an increase in DOC concentrations of up to 148 μM, resulting in a non-conservative behavior of DOM in the estuary. The high stratification combined with a decoupling between production and removal processes can explain the observed DOM accumulation. In the bottom layer DOM was released and quickly removed when oxygen was available, whereas in hypoxic waters the production of DOC, chromophoric DOM (CDOM) and fluorescent DOM (FDOM) was linearly related to oxygen consumption. Our work highlights the need of further studies combining chemical and biological information in order to gain new insights into the main processes responsible for DOM dynamics in this system.

68. 题目: Oxidation kinetics of biochar from woody and herbaceous biomass
文章编号: N20070307
期刊: Chemical Engineering Journal
作者: Chad A. Peterson, Robert C. Brown
更新时间: 2020-07-03
摘要:

The goal of this study was to determine oxidation kinetics for biochar produced from fast pyrolysis of various biomass feedstocks. In particular, the role of inherent ash content on the oxidation rate was evaluated. Thermogravimetric analysis (TGA) and fluidized bed combustion experiments were used to explore oxidation kinetics of six fast pyrolysis produced biochars with diverse ash content. Reaction rates varied by a factor of three under chemical kinetic-limited conditions, demonstrating inorganic content impacts oxidation rate. Chemical kinetic rate coefficients were proposed as a function of compositional parameters to determine overall fit and impact. Potassium content was found to have a positive correlation, best describing the differences in the oxidation kinetic rate coefficients. Additionally, feedstocks were subjected to a 1 M HCl acid wash mitigating the catalytic activity of the metals. Acid washed biochars had lower oxidation kinetic rates compared to their unwashed counterparts, indicating the removal of catalytically active metals reduced oxidation rate. Gas composition (CO/CO2) was measured during fluidized bed experiments for both acid-washed and unwashed biochars, which varied between the six biochars. Formation of CO2 was greatly affected by catalytic metals, finding potassium content to correlate well with a higher percentage of CO2 formation as compared to CO. Comparison of oxidation rates were made between the two experimental apparatuses to measure the effect of attrition on biochar oxidation.

69. 题目: Soil particle density as affected by soil texture and soil organic matter: 2. Predicting the effect of the mineral composition of particle-size fractions
文章编号: N20070306
期刊: Geoderma
作者: Joerg Ruehlmann, Martin Körschens
更新时间: 2020-07-03
摘要:

The particle density of soil (ρS) represents one of the basic physical properties of soil. However, measurement of this parameter is not part of common routine soil inventories in most countries. Therefore, pedotransfer functions (PTFs) were developed to calculate ρS. Here, we used a complex, hierarchically structured PTF to calculate ρS, separating the soil mineral substance (SMS) into clay, silt and sand fractions as well as separating the soil organic matter (SOM) into heavy-density and low-density fractions. This PTF was recently published, and here, we introduced an additional hierarchical level to consider the particle size fraction-dependent effect of the mineral composition on ρS. This extended PTF was calibrated and validated using data from soils of 16 German long-term experiments contrasting in soil texture and in soil mineral composition. Χ-ray diffraction analysis was applied to identify the mineralogical composition of the clay, silt and sand fractions. We fitted the particle densities of the identified minerals occurring in the respective particle size fractions by minimising the squared differences between the measured and predicted ρS. The model performed very well (RMSE = 0.011 Mg m−3 soil). According to the mechanistic base of the model and its hierarchical structure, it is very easy to include available information about the composition of any fraction or subfraction of soil mineral substances and to use the model to calculate the ρS corresponding to the specific site conditions.

70. 题目: The role of an urban park's tree stand in shaping the enzymatic activity, glomalin content and physicochemical properties of soil
文章编号: N20070305
期刊: Science of the Total Environment
作者: Joanna Lemanowicz, Samir A. Haddad, Agata Bartkowiak, Robert Lamparski, Piotr Wojewódzki
更新时间: 2020-07-03
摘要:

Soil enzymes play a key role in the circulation of nutrients and the functioning of the ecosystem. The aim of the study was to assess how the tree species of urban agglomerations affect soil quality and enzymatic activity (dehydrogenases DEH, catalase CAT, alkaline AlP and acid AcP phosphatase, protease PR, β-glucosidase GLU, and urease UR). To this end, soil samples were taken from beneath nine park trees. The risk of soil contamination by selected heavy metals (Pb, Ni, Cd) was also investigated against the background of the selected physicochemical properties. Enzyme activity results were used to calculate multi-parametric indices of soil quality: availability factor (AF), enzymatic pH indicator (AlP/AcP), biological index of fertility (BIF), geometric mean (GMea), alternation index (Al3), biochemical soil activity (BA16 and BA17). The results showed statistically significant differences in physicochemical and enzymatic properties of soil depending on tree species. Correlation analysis showed that the content of total organic carbon (TOC), total nirogen (TN), total phosphorus (TP) and humus (OM) in soil significantly influenced the activity of the studied enzymes and glomalin content. AF coefficient values (1.84%–18.19%) suggest that the bioavailability of available phosphorus (AP) was sufficient. The Pb, Ni, Cd content results were found to be low and did not exceed the permissible concentrations. DEH, CAT and AlP activity were highest under common hawthorn, and AcP, GLU and PR under northern white cedar. The calculated enzymatic indicators proved to be a sensitive and accurate indicator of the dynamics of changes taking place in the city park soil. Based on the results, an attempt can be made to assess the planning of sustainable development of studied areas of urban parks.

71. 题目: Stable Mercury Isotope Transition during Postdepositional Decomposition of Biomass in a Forest Ecosystem over Five Centuries
文章编号: N20070304
期刊: Environmental Science & Technology
作者: Wei Yuan, Xun Wang, Che-Jen Lin, Chuansheng Wu, Leiming Zhang, Bo Wang, Jonas Sommar, Zhiyun Lu, Xinbin Feng
更新时间: 2020-07-03
摘要: Organic soil is an important transient reservoir of mercury (Hg) in terrestrial ecosystems, but the fate of deposited Hg in organic forest soil is poorly understood. To understand the dynamic changes of deposited Hg on forest floor, the composition of stable Hg and carbon (C) isotopes in decomposing litters and organic soil layer was measured to construct the 500 year history of postdepositional Hg transformation in a subtropical evergreen broad-leaf forest in Southwest China. Using the observational data and a multiprocess isotope model, the contributions of microbial reduction, photoreduction, and dark reduction mediated by organic matter to the isotopic transition were estimated. Microbial reduction and photoreduction play a dominant role in the initial litter decomposition during first 2 years. Dark redox reactions mediated by organic matter become the predominant process in the subsequent 420 years. After that, the values of Hg mass dependent fractionation (MDF), mass independent fractionation (MIF), and Δ199Hg/Δ201Hg ratio do not change significantly, indicating sequestration and immobilization of Hg in soil. The linear correlations between the isotopic signatures of Hg and C suggest that postdepositional transformation of Hg is closely linked to the fate of natural organic matter (NOM). Our findings are consistent with the abiotic dark reduction driven by nuclear volume effect reported in boreal and tropical forests. We recommend that the dark reduction process be incorporated in future model assessment of the global Hg biogeochemical cycle.

72. 题目: Testing Os Staining Approach for Visualizing Soil Organic Matter Patterns in Intact Samples via X-ray Dual-Energy Tomography Scanning
文章编号: N20070303
期刊: Environmental Science & Technology
作者: Hongbing Zheng, Kyungmin Kim, Alexandra Kravchenko, Mark Rivers, Andrey Guber
更新时间: 2020-07-03
摘要: Challenges with in situ visualization of nonparticulate organics in porous materials limit understanding and modeling processes of transport, decomposition, and storage of organic compounds. In particular, it impedes deciphering the mechanisms driving accumulation and protection of soil organic matter (SOM), processes crucial for sustaining soil fertility and mitigating effects of global climate change. A recently proposed method of staining soil organics by OsO4 vapors with subsequent dual-energy X-ray computed microtomography scanning (μCT) offers new opportunities to visualize SOM within intact soil matrix. Our objective was to test the method's performance in staining different organic materials located in media with contrasting pore characteristics: (1) roots of switchgrass (Panicum virgatum L.), either placed within fine and coarse sands or grown within soil microcores, (2) biochar fragments, and (3) soils with relatively low and high C contents. We found that the method was effective in staining organic materials of root origin and the organics associated with fine soil particles, but not the biochar. The estimated percent of total C that reacted with OsO4 vapors ranged from 0.7% in plant roots to 3.2% in sand-free fraction of the high C soil and was only 0.2% in the studied biochar. Total soil C and Os concentrations were strongly linearly related, suggesting a potential for future method development. However, we would recommend caution when interpreting the results in cases when gas diffusion through the soil matrix is limited.

73. 题目: Coupled Manganese Redox Cycling and Organic Carbon Degradation on Mineral Surfaces
文章编号: N20070302
期刊: Environmental Science & Technology
作者: Dong Ma, Juan Wu, Peng Yang, Mengqiang Zhu
更新时间: 2020-07-03
摘要: Minerals, natural organic matter (NOM), and divalent manganese (Mn(II)) often coexist in suboxic/oxic environment. Multiple adsorption and oxidation processes occur in this ternary system, which are coupled to affect the fate of both OM and Mn therein and alter their chemical reactivity toward metals and other pollutants. However, the details about the coupling are poorly known although much has been gained for the binary systems. We determined the mutual influence of surface-catalyzed Mn(II) oxidation and humic acid (HA) adsorption and oxidation in a Fe(III) oxide (goethite)-HA-Mn(II) system at pH 5–8. The presence of Mn(II) substantially increased HA adsorption whereas HA greatly impaired the extent and rate of Mn(II) oxidation by O2 on goethite surfaces. The impacts were more pronounced at higher pH. Mn(II) oxidation produced β-MnOOH, γ-MnOOH, and Mn3O4 which in turn oxidized HA, producing small organic acids. The presence of HA markedly altered the composition of Mn(II) oxidation products by inhibiting the formation of β-MnOOH while favoring the production of γ-MnOOH and Mn(II) adsorbed on the HA-mineral assemblage. Nonconducting γ-Al2O3 exhibited similar but weaker effects than semiconducting goethite in the above processes. Our results suggest that similar to Mn-oxidizing microorganisms, mineral surfaces can drive the coupling of the Mn redox cycle with NOM oxidative degradation under suboxic/oxic and circumneutral/alkaline conditions.

74. 题目: Adsorption of Divalent Copper Ions from Synthetic Wastewater Using Layered Double Hydroxides (NiZnFe) and Its Composites with Banana Biochar and Carbon Nanotubes
文章编号: N20070301
期刊: Water, Air, and Soil Pollution
作者: M. Shafiq, A. A. Alazba, M. T. Amin
更新时间: 2020-07-03
摘要: The adsorption potential of layered double hydroxides (LDH) of nickle–zinc–iron (NiZnFe) and its composites with single-wall carbon nanotubes (CNTs) and banana biochar (Bb) was investigated for divalent copper (Cu2+) removal in a batch system. Field emission scanning electron microscopy and FT-IR spectra confirmed the adsorption of Cu2+ onto LDH (NiZnFe) and its composites with Bb (LDH/Bb) and CNTs (LDH/cnt). The optimum equilibrium contact time was determined to be ~ 30 min, with LDH/Bb displaying the maximum uptake and removal efficiency (95%) for an initial Cu2+ concentration of 20 mg L−1. Pseudo-second-order kinetic models presented high R2 values (1.0) for all adsorbents, indicating good agreement between the theoretical adsorption capacities with experimental values. Multistep adsorption with both the surface and pore diffusion mechanism was suggested as well based on the intraparticle diffusion kinetic model. An optimum pH of 5.0 was considered with an increase in the uptake of Cu2+ and its removal efficiency, wherein LDH/Bb presented a greater removal efficiency and higher Cu2+ uptake compared with that of LDH (NiZnFe) and LDH/cnt. A gradual increase in Cu2+ uptake was observed in association with an increase in adsorbent dose from 0.2 to 0.5 g, with insignificant changes upon further increasing the dose of the adsorbent from 0.5 to 0.9 g. An increase in the initial Cu2+ concentrations from 10 to 100 mg L−1 resulted in a decrease in the removal efficiency, whereas Cu2+ uptake increased almost linearly in the Cu2+ concentration range of 10–60 mg L−1. Results of experimental data fitting using the Langmuir and Freundlich isotherm models suggest a dominance of monolayer adsorption, although multilayer adsorption appears to occur onto adsorbents with heterogeneous surfaces. Notably, chemisorption was also proposed to occur owing to the values of mean free energy of adsorption falling in the 8–16-kJ mol−1 range, as calculated using the Dubinin–Radushkevich isotherm model. Importantly, the use of the SIP isotherm model indicated LDH/Bb to exhibit higher energy of adsorption and degree of heterogeneity than other two adsorbents. Thus, biochar or CNTs composited NiZnFe-LDH could serve as efficient adsorbents for Cu2+ removal from wastewater streams.

75. 题目: Neutralization of red mud using bio-acid generated by hydrothermal carbonization of waste biomass for potential soil application
文章编号: N20070209
期刊: Journal of Cleaner Production
作者: Chongqing Wang, Xue Zhang, Ruirui Sun, Yijun Cao
更新时间: 2020-07-02
摘要:

Red mud, a by-product generated from alumina industry, poses serious environmental issues and safety risks. Strong alkalinity of red mud is a key factor affecting its potential soil application and comprehensive utilization. A novel process employing natural biomass without addition of chemicals was proposed for remediation of red mud. Hydrothermal carbonization (HTC) of local fallen leaves was conducted to obtain solution containing bio-acids (SBA) and hydrochar. Factors of HTC and stirring process were investigated on neutralization of red mud using SBA. The presence of small-molecule compounds such as furfural and organic acids in SBA is identified by GC-MS. SBA is effective to lower the alkalinity of red mud, and the pH value of red mud is reduced from 9.88 to 6.65 under experimental conditions. Neutralization mechanism was examined by various characterizations including XRD, FTIR, TG and EPMA. Neutralization results in little change of red mud, and it is deduced that small-molecule organic acids only remove free alkali without destruction of minerals. Soil matrix prepared by mixing the neutralized red mud and hydrochar is favorable to plant growth. The developed process including HTC of waste biomass, neutralization of red mud and fabrication of soil matrix for plant growth is green, sustainable and environmentally friendly, thus highly promising for potential applications.

76. 题目: Late Cretaceous–Paleogene palaeoclimate reconstruction of the Gippsland Basin, SE Australia
文章编号: N20070208
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Lian Jiang, Wenjing Ding, Simon C. George
更新时间: 2020-07-02
摘要:

The Cretaceous–Paleogene palaeovegetation and palaeoclimate in the Gippsland Basin was reconstructed using vascular plant-derived biomarkers, and are consistent with other proxy evidence for palaeoclimate (e.g. spore-pollen assemblages and plankton foraminifera oxygen isotopes). Variation in the higher plant-derived aliphatic and aromatic sesquiterpenoids, diterpenoids and triterpenoids resulted from vegetation succession, and are different in the T. lilliei, F. longus, L. balmei, M. diversus, P. asperopolus and N. asperus palynological biozones. Analyses of the oleanane index, the higher plant parameter, the higher plant index, the higher plant fingerprint, and various aliphatic and aromatic angiosperm/gymnosperm indices indicate the late Cretaceous–Paleogene (ca. 80–40 Ma) palaeoclimate in the Gippsland Basin was initially warm (Campanian T. lilliei Biozone), and then changed in this way: → cool (Maastrichtian upper F. longus Biozone), → warm (Paleocene L. balmei Biozone), → hot (early Eocene M. diversus and P. asperopolus Biozones), → warm and then cool (middle Eocene N. asperus Biozone). This changing climate trend is mostly consistent with global climate changes. In comparison to the analogous Taranaki Basin (western New Zealand), the Gippsland Basin is inferred to have had a less gymnosperm-dominated rainforest and a warmer climate in the late Cretaceous. During the Paleogene the palaeoclimate was similar in the two basins, as deduced from the angiosperm/gymnosperm indices of the sedimentary rocks.

77. 题目: Exploring the relative changes in dissolved organic matter for assessing the water quality of full-scale drinking water treatment plants using a fluorescence ratio approach
文章编号: N20070207
期刊: Water Research
作者: Tahir Maqbool, Yanling Qin, Quang Viet Ly, Jiaxing Zhang, Chengyue Li, Muhammad Bilal Asif, Zhenghua Zhang
更新时间: 2020-07-02
摘要:

This study aims to extend and demonstrate the application of fluorescence spectroscopy for monitoring the water quality of three differently operated full-scale drinking water treatment plants located in the Shenzhen city (China). A ratio of fluorescent organic matter (FDOM), which describes relative changes in humic-like to protein-like fluorescence, was used to explain mechanisms behind the physicochemical processes. The fluorescence components obtained through individual and combined parallel factor analysis (PARAFAC) modeling revealed the presence of humic-like (C1) and protein-like (C2) structures in the DOM. The C1/C2 ratio provided a direct relationship between the seasonal variations and DOM composition. Wet season generated DOM enriched with humic-like fluorescence, while dry season caused a higher release of protein-like fluorescence. The fluorescence ratio presented unique patterns of DOM in treatment trains. The chemical pretreatment and disinfection unit processes showed a higher tendency to remove the humic-like fluorescence. However, the C1/C2 ratio increased during physical treatment processes such as coagulation-precipitation and sand filtration, indicating preferential removal of protein-like fluorescence. The DOM composition in influent directly (R2 = 0.77) influenced the relative intensities of fluorescence components in the treated water. Compared to the dry season, the wet season caused significant changes in DOM composition and produced treated water enriched with humic-like fluorescence. This fluorescence ratio offers an approach to explore the role of different treatment units and determine the factors affecting the composition of DOM in the surface water and water treatment plants.

78. 题目: The occurrence, characteristics, transformation and control of aromatic disinfection by-products: A review
文章编号: N20070206
期刊: Water Research
作者: Xiaoyu Liu, Li Chen, Mengting Yang, Chaoqun Tan, Wenhai Chu
更新时间: 2020-07-02
摘要:

With the development of analytical technology, more emerging disinfection by-products (DBPs) have been identified and detected. Among them, aromatic DBPs, especially heterocyclic DBPs, possess relatively high toxicity compared with regulated DBPs, which has been proved by bioassays. Thus, the occurrence of aromatic DBPs is of great concern. This article provides a comprehensive review and summary of the characteristics, occurrence, transformation pathways and control of aromatic DBPs. Aromatic DBPs are frequently detected in drinking water, wastewater and swimming pool water, among which swimming pool water illustrates highest concentration. Considering the relatively high concentration and toxicity, halophenylacetonitriles (HPANs) and halonitrophenols (HNPs) are more likely to be toxicity driver among frequently detected phenyl DBPs. Aromatic DBPs can be viewed as important intermediate products of dissolved organic matter (DOM) during chlor(am)ination. High molecular weight DOM could convert to aromatic DBPs via direct or indirect pathways, and they can further decompose into regulated aliphatic DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs) by ring opening and side chain cleavage. Even though no single DBPs control strategy is efficient to all aromatic DBPs, the decrease of overall toxicity may be achieved by several methods including absorption, solar radiation and boiling. By systematically considering aromatic DBPs and aliphatic DBPs, a better trade-off can be made to reduce health risk induced by DBPs.

79. 题目: Low water treatability efficiency of wildfire-induced dissolved organic matter and disinfection by-product precursors
文章编号: N20070205
期刊: Water Research
作者: Huan Chen, Habibullah Uzun, Alex T. Chow, Tanju Karanfil
更新时间: 2020-07-02
摘要:

Wildfire could alter both the quantity and composition of terrestrial organic matter exported into source water, and water treatability of fire-impacted dissolved organic matter (DOM) could be different from its unburned counterpart. Currently, there is no standard protocol to treat wildfire-impacted source water. To identify the best treatment practices in handling post-fire runoffs, we conducted a systematic controlled study using leachates of unburned white fir (Abies concolor) and Ponderosa pine (Pinus ponderosa) and black and white ashes (collected immediately and one year after the 2013 Rim Fire, California) to evaluate coagulation and oxidation strategies for controlling disinfection byproducts (DBPs) formation. Results showed that the efficiency (%) of alum coagulation in removing dissolved organic carbon and nitrogen followed the order of litter > ash immediately after the fire > ash one year after the fire. Alum coagulation was less effectiveness in removing DOM and DBP precursors in ash leachates, compared to litter leachates. This may be attributed to the loss of side chains and the decrease of DOM molecular weight during the wildfire, thus inducing lower removal efficiency of the DOM and DBP precursors during the alum coagulation. Considering use of brominated flame retardants by firefighters, the addition of bromide (Br) (100 μg/L) greatly increased the formation of haloacetonitriles by chlorine, and this increase was relatively lower in ash leachates. The influence of reaction time and pH on DOM reactivity was similar among the leachates of litter and ash samples. Our results show that alum coagulation followed by chloramination at alkaline pH is an effective strategy for reducing post-fire DBP formation in drinking water.

80. 题目: Quantifying denitrification following floodplain restoration via the two-stage ditch in an agricultural watershed
文章编号: N20070204
期刊: Ecological Engineering
作者: Shannon L. Speir, Jennifer L. Tank, Ursula H. Mahl
更新时间: 2020-07-02
摘要:

In agricultural streams, constructed floodplains have been shown to expand bioreactive surface area and enhance nitrate (NO3-N) removal via microbial denitrification, thereby reducing export to downstream ecosystems. At the Shatto Ditch Watershed (Indiana, USA), 0.6 km of two-stage ditch was constructed at the watershed outlet in 2007, while an additional 3.7 and 2.7 km were constructed in 2017 and 2018, respectively. We quantified denitrification following floodplain construction using experimental incubations of stream sediments and floodplain soils from Spring 2017 to Spring 2019. We measured dissolved dinitrogen gas (N2) concentrations using membrane inlet mass spectrometry (MIMS) and found that denitrification on unconsolidated stream sediments was minimally impacted by stream dredging during two-stage construction in 2017 and 2018. In contrast, even one year after the 2017 construction, denitrification on floodplain soils fell below detection limits; we finally observed measurable rates in Spring 2019. As predicted, stream sediment denitrification was driven by water column NO3-N concentration, while organic matter limited denitrification on floodplain soils. Floodplains constructed via the two-stage ditch can increase NO3-N removal by >20% in agricultural watersheds, representing an effective ecological engineering solution to combat downstream eutrophication. However, our results also show that denitrification on floodplain soils may take longer to recover from construction-related activities as organic matter builds up more slowly over time. As such, lags in the recovery or enhancement of ecosystem function are important to consider when documenting restoration success.

 共 8178 条记录  本页 20 条  本页从 61-80 条  4/409页  首页 上一页  1 2 3 4 5 6 7 8 9  下一页  末页   

本数据库数据来源自各期刊,所有权归属各期刊。数据仅供分享学习,不作商业用途,特此申明。