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17501. 题目: Geochemical and mineralogical constraints in iron ore tailings limit soil formation for direct phytostabilization
文章编号: N18091702
期刊: Science of The Total Environment
作者: Songlin Wu, Yunjia Liu, Gordon Southam, Lachlan Robertson, Tsz Ho Chiu, Adam T. Cross, Kingsley W. Dixon, Jason C. Stevens, Hongtao Zhong, Ting-Shan Chan, Ying-Jui Lu, Longbin Huang
更新时间: 2018-09-17
摘要: The present study aimed to characterize key physico-chemical and mineralogical attributes of magnetite iron (Fe) ore tailings to identify potential constraints limiting in situ soil formation and direct phytostabilization. Tailings of different age, together with undisturbed local native soils, were sampled from a magnetite mine in Western Australia. Tailings were extremely alkaline (pH > 9.0), with a lack of water stable aggregate and organic matter, and contained abundant primary minerals including mica (e.g., biotite), with low specific surface area (N2-BET around 1.2 m2 g−1). These conditions remained relatively unchanged after four years' aging under field conditions. Chemical extraction and spectroscopic analysis [e.g., X-ray diffraction (XRD) and synchrotron-based Fe K edge X-ray absorption fine structure spectroscopy (XAFS) analysis] revealed that the aging process decreased biotite-like minerals, but increased hematite and magnetite in the tailings. However, the aged tailings lacked goethite, a compound abundant in natural soils. Examination using backscattered-scanning electron microscope - energy dispersive X-ray spectrometry (BSE-SEM-EDS) revealed that aged tailings contained discrete sharp edged Fe-bearing minerals that did not physically integrate with other minerals (e.g., Si/Al bearing minerals). In contrast, Fe minerals in native soils appeared randomly distributed and closely amassed with Si/Al rich phyllosilicates, with highly eroded edges. The lack of labile organic matter and the persistence of alkaline-saline conditions may have significantly hindered the bioweathering of Fe-minerals and the biogenic formation of secondary Fe-minerals in tailings. However, there is signature that a native pioneer plant, Maireana brevifolia can facilitate the bioweathering of Fe-bearing minerals in tailings. We propose that eco-engineering inputs like organic carbon accumulation, together with the introduction of functional microbes and pioneer plants, should be adopted to accelerate bioweathering of Fe-bearing minerals as a priority for initiating in situ soil formation in the Fe ore tailings.
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17502. 题目: Characterization of disinfection byproduct formation and associated changes to dissolved organic matter during solar photolysis of free available chlorine
文章编号: N18091701
期刊: Water Research
作者: Tessora R. Young, Wentao Li, Alan Guo, Gregory V. Korshin, Michael C. Dodd
更新时间: 2018-09-17
摘要: Solar irradiation of chlorine-containing waters enhances inactivation of chlorine-resistant pathogens (e.g., Cryptosporidium oocysts), through in situ formation of ozone, hydroxyl radical, and other reactive species during photolysis of free available chlorine (FAC) at UVB-UVA wavelengths of solar light (290–400 nm). However, corresponding effects on regulated disinfection byproduct (DBP) formation and associated dissolved organic matter (DOM) properties remain unclear. In this work, when compared to dark chlorination, sunlight-driven FAC photolysis over a range of conditions was found to yield higher DBP levels, depletion of DOM chromophores and fluorophores, preferential removal of phenolic groups versus carboxylic acid groups, and degradation of larger humic substances to smaller molecular weight compounds. Control experiments showed that increased DBP levels were not due to direct DOM photolysis and subsequent dark reactions with FAC, but to co-exposure of DOM to FAC and reactive species (e.g., O3, HO, Cl, Cl2•-, ClO) generated by FAC photolysis. Because solar chlorine photolysis can enable inactivation of chlorine-resistant pathogens at far lower CTFAC values than chlorination alone, the increases in DBP formation inherent to this approach can likely be offset to some extent by the ability to operate at significantly decreased CTFAC. Nonetheless, these findings demonstrate that applications of solar chlorine photolysis will require careful attention to potential impacts on DBP formation.
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17503. 题目: Phosphorus transformations in stream bank sediments in Iowa, USA, at varying redox potentials
文章编号: N18091610
期刊: Journal of Soils and Sediments
作者: Suroso Rahutomo, John L. Kovar, Michael L. Thompson
更新时间: 2018-09-16
摘要: Purpose: Stream bank erosion is one of the main sources of suspended sediments in stream water, and it often carries phosphorus with it. With a controlled laboratory study, we investigated the changes in different forms of P in stream bank sediments at varying redox potentials. We hypothesized that there could be increases in labile forms of solid-phase P under low redox conditions. Materials and methods: Sediment samples representing four major stratigraphic units were collected from alluvial banks of Walnut Creek in Jasper County, Iowa: Camp Creek, Roberts Creek, and Gunder members of the Holocene-age De Forest Formation and pre-Illinoian till, a glacial deposit that is older than 500,000 years. We compared three treatments: no anaerobic incubation, anaerobic incubation, and anaerobic incubation with addition of glucose. After each treatment, soil P fractions were determined and classified as water-extractable P, labile P, slowly cycling P, stable P, and residual P. Labile P is extractable with 0.5 M NaHCO3, slowly cycling P is extractable with 0.1 M NaOH or 1 M HCl, stable P is extractable with concentrated HCl, and residual P is associated with acid-insoluble compounds in the soil. Results and discussion: Redox potential of the equilibrated systems was significantly less when sediments were incubated anaerobically than when they were not incubated, especially when glucose was added to the anaerobic incubation. Variations in redox potential did not significantly affect the total P, organic or inorganic stable P, or residual P in the sediments. In contrast, we found that the amount of inorganic labile P tended to increase at the same time that slowly cycling P associated with Fe decreased. Conclusions: The younger sediments, higher in the stratigraphic profile and with more organic matter, had greater labile P and slowly cycling P that was associated with Fe, reflecting a greater potential to contribute to elevated levels of P in the stream water if subjected to low redox potential in the stream environment. The forms of P in the four bank sediments were redistributed among the fractions by reducing conditions. There was an increase in the concentration of inorganic labile P, which coincided with a decrease in slowly cycling P associated with Fe, especially in the Holocene-age sediments. These sediments appear to have a greater potential to contribute to elevated levels of P in the stream water when they are subjected to low redox potential in the stream environment.

17504. 题目: Adsorption of Ammonium in Aqueous Solutions by the Modified Biochar and its Application as an Effective N-Fertilizer
文章编号: N18091609
期刊: Water, Air, & Soil Pollution
作者: Lu Shang, Hao Xu, Shaobin Huang, Yongqing Zhang
更新时间: 2018-09-16
摘要: Water body contamination by ammonium is of major concern because it poses huge risks and harm to the environment and human health. Biochar derived from waste spruce sawdust was modified by soaking it into HNO3 and Na2CO3 to obtain a low-cost and high-efficiency adsorbent. The factors affecting the removal of ammonium from aqueous solutions, the mechanisms by which ammonium was adsorbed by the modified biochar, and the potential application of the post-adsorption biochar as an effective N-fertilizer were studied. pH and co-existing ions were affirmed to affect the capacity of the modified biochar to adsorb ammonium. The pseudo-second order kinetic model and Freundlich model could best fit the ammonium adsorption data. Cation exchange was the most important mechanism involved in ammonium adsorption by the modified biochar. The high adsorption capacity of the modified biochar makes it a promising alternative adsorbent to remove ammonium from wastewater. Furthermore, the seedling bioassay experiment demonstrated that the post-adsorption biochar can be cycled back directly to the soil as an effective N-fertilizer.

17505. 题目: Lignin phenols in the paleoenvironmental reconstruction of high mountain peatlands from Atlantic Rainforest, SE - Brazil
文章编号: N18091608
期刊: CATENA
作者: Lúcio Fábio Lourençato, Marcelo Corrêa Bernardes, Andressa Cristhy Buch, Emmanoel Vieira Silva-Filho
更新时间: 2018-09-16
摘要: Tropical peatlands are very different from boreal and temperate regions, because they have particular climatic characteristics and different vegetation types. Similarly, high mountain peatlands differ significantly from those found at low altitudes. Lignin components were investigated as phyto-physiological proxies of landscape evolution in two big national environmental conservation parks of Southeastern Brazil. Lignin phenols showed a high degree of humification and indicated the same land-use for both forest parks, suggesting minimal anthropic intervention over the last 150 years, predominating native grasslands. However, total organic carbon (TOC) and total nitrogen (TN) parameters evidenced the influence of indirect effects of human activities, mainly from atmospheric deposition since 1950s, associated to the early Brazilian industrial development. This study reinforces the importance of protection and conservation to those pristine areas.
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17506. 题目: Marine sulfur cycle evidence for upwelling and eutrophic stresses during early triassic cooling events
文章编号: N18091607
期刊: Earth-Science Reviews
作者: Alan Stebbins, Thomas J. Algeo, Leopold Krystyn, Harold Rowe, Michael Brookfield, Jeremy Williams, Steven W. Nye, Robyn Hannigan
更新时间: 2018-09-16
摘要: Perturbations to the global carbon and sulfur cycles recurred episodically throughout the ~5-Myr-long Early Triassic, in the aftermath of the end-Permian mass extinction, the largest biocrisis in Earth's history. In this study, analyses of carbonate-associated sulfate (CAS) sulfur, CAS oxygen, and pyrite sulfur-isotope ratios in a continental shelf section from the southern Neo-Tethys Ocean (Spiti Valley, India) provide new insights into the Early Triassic marine sulfur cycle. Secular variation in CAS sulfur-isotope values at Spiti is similar to that in South China, suggesting that CAS was a robust recorder of a global seawater sulfate signal. The Spiti CAS and pyrite δ34S profiles show that the highest rates of pyrite burial coincided with cooler sea-surface temperatures. We infer that climatic cooling steepened equator-to-pole temperature gradients, invigorating thermohaline overturning circulation, and enhancing upwelling of nutrients that stimulated marine productivity and organic carbon sinking fluxes. Enhanced productivity fueled and sustained microbial respiration, increased oxygen demand, and, within the southern Neo-Tethys, caused the zone of microbial sulfate reduction to migrate upwards and become more connected to the water column. Microbial sulfate reduction, under these conditions, was no longer limited by organic matter or sulfate availability, leading to burial of more 34S-depleted pyrite and 34S- and 18O-enrichment of the oceanic sulfate pool. This environmental scenario suggests possible environmental stresses related to eutrophication during positive carbon-isotope excursions around the Griesbachian-Dienerian, Dienerian-Smithian, and Smithian-Spathian boundaries. Additionally, the difference between CAS and pyrite sulfur-isotope values, Δ34SCAS-pyr, slowly rose through the Early Triassic, reflecting a slow increase in seawater sulfate concentrations following a minimum close to the Permian-Triassic boundary.

17507. 题目: Origin of the Neoproterozoic Fulu Iron Formation, South China: Insights from Iron Isotopes and Rare Earth Element Patterns
文章编号: N18091606
期刊: Geochimica et Cosmochimica Acta
作者: Vincent Busigny, Noah J. Planavsky, Elizabeth Goldbaum, Maxwell A. Lechte, Lianjun Feng, Timothy W. Lyons
更新时间: 2018-09-16
摘要: In the Neoproterozoic Era there was widespread deposition of iron formations in close association with global or near glaciations. These ‘Snowball Earth’ glaciations likely played a key role in iron formation distribution and deposition. However, the environmental conditions, Fe sources, and formation mechanisms remain debated. Here we present the rare earth element geochemistry and Fe isotope composition of the synglacial iron formation within the Neoproterozoic Fulu Formation, South China. The Fulu iron formation consists of layers of authigenic minerals (mainly hematite) and detrital components (quartz, feldspars, Fe chlorite, and minor biotite). Positive Eu anomalies in one of the Fulu localities indicate a hydrothermal influence, suggesting that Fe was mainly sourced from distal hydrothermal systems. The bulk-rock Fe isotope composition of the Fulu iron formation shows a large range, with δ56Fe from -0.23 to +1.78‰. Correlation between bulk-rock δ56Fe values and Al/Fe ratios demonstrates that δ56Fe variability reflects, in part, varying proportions of authigenic versus detrital components. The Fe isotope composition of authigenic hematite is calculated by a linear regression and shows δ56Fe between +0.83 and +2.21‰, with an average at +1.54 ± 0.50‰ (2σ, n=41). Using a dispersion-reaction model, the high δ56Fe values of hematite constrain local dissolved O2 concentrations of the ocean to less than 0.4 nmol/L, even in the shallow part of the water column. This relationship is consistent with highly reducing conditions in the Neoproterozoic oceans favored by isolation from the atmosphere by a sea ice. We attribute the extremely positive values to partial iron oxidation in waters that were cold relative to modern surface oceans. The dominant occurrence of hematite supports an abiotic precipitation pathway, given that biological activity would have introduced organic matter to the sediments and led to partial reduction of Fe(III) oxides and subsequent formation of magnetite and/or siderite, as is observed in Archean and Paleoproterozoic iron formations. Oxic glacial meltwater and/or O2 vertical transfer from the atmosphere to the upper ocean linked to ice dynamics is likely to have mediated the abiotic oxidation. We propose that vertical transfer of O2 resulted from the deposition of snow that trapped air bubbles at the top of the glacier coupled to a melting of the bottom of the glacier, which in combination delivered a limited but continuous amount of O2 to the ocean.

17508. 题目: A critical review of the application of chelating agents to enable Fenton and Fenton-like reactions at high pH values
文章编号: N18091605
期刊: Journal of Hazardous Materials
作者: Ying Zhang, Minghua Zhou
更新时间: 2018-09-16
摘要: To overcome the drawback of low pH requirement of the classical Fenton reaction, researchers have applied chelating agents to form complexes with Fe and enable Fenton reaction at high pHs, which is reviewed in this article. The chelating agents reviewed include humic substances, polycarboxylates, aminopolycarboxylic acids, and polyoxometalates. Ligands affect the reactivity of Fe-complexes by changing their redox potentials, promoting their reaction with H2O2, and competing with target contaminants for the oxidative species. Fe(III)-complexes are reduced to Fe(II)-complexes by O2•- not H2O2, as indicated by their redox potentials. The stability constants of Fe-complexes increase with increasing pKa values of the corresponding ligands and also with increasing charge density of the metal ions. A higher stability constant of Fe(III)-complex indicates higher reaction rate of corresponding Fe(II)-complex with H2O2 and lower reduction rate of Fe(III)-complex to Fe(II)-complex. OH, O2•-, and ferryl species were reported to be the reactive species on the contaminant removal in the chelate-modified Fenton process. The generation of these species depends on the chelating agents and reaction conditions. The process is very efficient in degrading contaminants, indicating a potential treatment approach for the pollution remediation at natural pH.

17509. 题目: Screening of Wheat Straw Biochars for the Remediation of Soils Polluted with Zn (II) and Cd (II)
文章编号: N18091604
期刊: Journal of Hazardous Materials
作者: Ting-Ting Qian, Ping Wu, Qiu-Ying Qin, Ying-Nan Huang, Yu-Jun Wang, Dong-Mei Zhou
更新时间: 2018-09-16
摘要: The immobilization behaviors of Zn(II) and Cd(II) by wheat straw (WS) biochars could vary with the soil conditions. In the acidic environment, WS biochars produced at low temperature were more competent than those produced at high temperature on Zn(II) and Cd(II) immobilization; while WS biochars produced at high temperature were more effective than those produced at low temperature in the alkaline environment. The ions in the porewater could compromise the sorption capacities of Zn(II) and Cd(II) by WS biochars in acidic soils, while could enhance them in alkaline soils. For biochars produced at the same temperature, residence time had little effect on their behaviors of Zn(II) and Cd(II) immobilization. Only a small portion of immobilized Zn(II)/Cd(II) could be released from WS biochar in the simulated acid rain. Compared with Zn(II)/Cd(II) adsorbed on the acidic functional groups, Zn(II)/Cd(II) precipitates were more stable in 0.01 M CaCl2 solution. Most of the Zn(II) and Cd(II) species on biochar could be released in 1 mM citric acid solution. The immobilized Zn(II) and Cd(II) on WS biochar are likely to be released into the soil environment in the long run.

17510. 题目: Unraveling complex removal behavior of landfill leachate upon the treatments of Fenton oxidation and MIEX® via two-dimensional correlation size exclusion chromatography (2D-CoSEC)
文章编号: N18091603
期刊: Journal of Hazardous Materials
作者: Bilal Aftab, Jin Hur
更新时间: 2018-09-16
摘要: The complex removal behavior of stabilized landfill leachate was explored for the treatments of Fenton oxidation (FnO) and magnetic ion exchange (MIEX®) resin using two-dimensional correlation size exclusion chromatography (2D-CoSEC) and fluorescence excitation emission matrix-parallel factor analysis (EEM-PARAFAC). The overall removal rates of the bulk parameters (~45% for dissolved organic carbon and ~78% for UV absorbance) were similar between the two treatment options, while distinct differences were found with respect to different molecular sizes and chemical composition. The resin treatment eliminated humic substances (HS) and low molecular weight acid (LMWA) fractions to a greater extent than other fractions (i.e., HS: 62% and LMWA: 99%), while low molecular weight neutral (LMWN) and biopolymers (BP) fractions were more effectively treated by the FnO with the removal rates of 56% and 92%, respectively. The 2D-CoSEC further revealed that the sequential or preferential changes of different size fractions with increasing the resin or H2O2 were opposite between the two treatment options in the order of HS → LMWA → LMWN → BP for MIEX®. Due to their complementary roles in treating leachate, the combined processes removed a wider ranges of different molecular sizes compared to the single operation.
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17511. 题目: Stabilization/Solidification Characteristics of Organic Clay Contaminated by Lead When Using Cement
文章编号: N18091602
期刊: Journal of Hazardous Materials
作者: Yize Pan, Joseph Rossabi, Chonggen Pan, Xinyu Xie
更新时间: 2018-09-16
摘要: Research about cement treated soil has examined various characteristics of strengthened and stabilized soil, but has mainly focused on either the unconfined compressive strength or potentially toxic element (PTE) stabilizing results respectively in response to cement dosing. This study investigates how factors including cement concentration, lead concentration, humic/fulvic acid content and curing age affect these two geotechnical and environmental characteristics. A laboratory study was conducted to measure unconfined compressive strength, and lead leaching under several test conditions. Knowing that humic acid and fulvic acid can weaken cementation in cement treated soil but can stabilize PTEs such as lead by different chemical reactions, it was found that the acids generally reduce lead stabilization in cement treated soil. In addition, the stabilized strength reaches a peak at a specific lead content in soil. Finally, scanning electron microscopy was used to observe more detailed changes and mechanisms.
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17512. 题目: Investigations of relationships among aggregate pore structure, microbial biomass, and soil organic carbon in a Mollisol using combined non-destructive measurements and phospholipid fatty acid analysis
文章编号: N18091601
期刊: Soil and Tillage Research
作者: Aizhen Liang, Yan Zhang, Xiaoping Zhang, Xueming Yang, Neil McLaughlin, Xuewen Chen, Yafei Guo, Shuxia Jia, Shixiu Zhang, Lixia Wang, Jianwu Tang
更新时间: 2018-09-16
摘要: Limitations of traditional measurement methods have impeded progress in understanding the role of soil aggregation in protecting soil organic carbon (SOC) from decomposition by soil microbes living in pore spaces. In this paper, we used the Scanning Electronic Microscope (SEM) and X-ray micro Computed Tomography (micro-CT) to study the relationships of the aggregate pore structure and microbial distribution in the interior and exterior of soil aggregates, and thereby gained an insight into protection of carbon within macroaggregates of an undisturbed Mollisol in northeastern China. There were close relationships between soil pore structure and distribution of soil microbes and soil organic carbon (SOC), but they were different on the exterior and interior of soil aggregate. On the exterior of macroaggregates, there were negative relationships between soil porosities, the number of pores and SOC, especially for soil pores in the 10–30 μm and 30–100 μm classes, indicating these two pore sizes are unlikely to help sequester C. In contrast, there was a positive correlation between soil pores > 100 μm and SOC. Furthermore, soil pore structure had no impact on soil microbial biomass and density or on SOC contents in the interior of soil aggregates. This study provides a new method by combining SEM with micro-CT technology for linking soil structure and soil microbial properties with C sequestration and SOC changes.

17513. 题目: The sources and transformations of dissolved organic matter in the Pearl River Estuary, China, as revealed by stable isotopes
文章编号: N18091506
期刊: Journal of Geophysical Research: Oceans
作者: Feng Ye, Wei Guo, Gangjian Wei, Guodong Jia
更新时间: 2018-09-15
摘要: To investigate the sources and transformation processes of bulk marine dissolved organic matter (DOM), seasonally collected water samples from the Pearl River Estuary (PRE), south China, were analyzed for concentration and stable isotopic ratios (δ13C and δ15N) of DOM. The δ13C values clearly indicated a shift of dissolved organic carbon (DOC) sources from terrigenous material in the river to predominantly plankton in the lower estuary. The distribution of δ13C during the estuarine mixing, in combination with sharp decrease in DOC concentration, provided strong evidence for a substantial DOC removal in the salinity range of 5 to 22. In contrast to δ13C, the δ15N of DOM exhibits a strong seasonality, implying a clear decoupling of estuarine DOC and dissolved organic nitrogen (DON) dynamics. During dry periods with low river discharge, sewage‐derived DON contributed significantly to the riverine loading. While freshwater‐saltwater mixing is important in regulating the distribution of DON, the distribution of δ15N along the salinity gradient provided strong evidence for active sediment–water interaction and adsorption/desorption processes at the middle to high salinities. During wet periods, severe soil loss and erosion, and/or in situ biological production, adsorption onto suspended particles dominate the riverine DON fluxes, whereas the DON dynamics might be governed by different biogeochemical processes between spring and summer, as reflected by distinct δ15DON patterns in the estuarine zone. In spring, highly degraded DON originating from soil experienced little further biological alternation during estuarine mixing, whereas there was a tight coupling of DON production and consumption in summer.

17514. 题目: Effects of shrub encroachment on vertical changes in soil organic carbon in Mongolian grasslands: using a multi-biomarker approach
文章编号: N18091505
期刊: Plant and Soil
作者: Luhong Zhou, He Li, Haihua Shen, Yunping Xu, Yinghui Wang, Aijun Xing, Yankun Zhu, Shangzhe Zhou, Jingyun Fang
更新时间: 2018-09-15
摘要: Aims: In recent decades, ecologists have investigated the effects of shrub encroachment on regional carbon cycling in semi-arid and arid regions. Although differences in carbon sequestration and stocks have been recognized in different soil layers, the vertical changes in soil organic carbon (SOC) at the molecular level following shrub encroachment remain unexplored. In this study, we used biomarkers to assess the impacts of shrub encroachment on SOC composition. Methods: We collected soil samples along the 1-m profile within shrub patches and grassy matrix in three typical shrub-encroached grassland (SEG) sites in Inner Mongolia, and quantified the vertical distribution of the biomarkers, including free lipids, bound lipids and lignin-derived phenols. Results: The principal component analysis (PCA) of the biomarker data showed that samples in the grassy matrix had strong positive loadings along the first two components (PCs); in contrast, samples in the upper 50 cm of the shrub patches had negative loadings along the first component (PC1) as well as a narrower range. The acid to aldehyde ratios of the vanillyl and syringyl type monomers increased simultaneously along the 1-m profile in the grassy matrix; however, this trend was not observed in the shrub patches. In addition, the vanillyls to syringyls to cinnamyls ratio was approximately 3:2:1 in the shrub patches and 3:2:1 or 2:2:1 in the grassy matrix. Conclusions: Shrub encroachment altered the vertical patterns in SOC composition, especially in the upper 50 cm, as well as the oxidation status of lignin-derived phenols along the entire 1-m profile. Further, shrub encroachment influenced the soil carbon composition under the shrub canopy as well as in the grassy matrix due to the sprawling canopies and the horizontal extension of the root systems of the encroaching shrubs. These results provided new insights into the vertical patterns of SOC changes after shrub encroachment at the molecular level and have important implications for understanding the mechanisms of soil carbon dynamics with changes in vegetation structure and composition.

17515. 题目: Organic matter facilitates the binding of Pb to iron oxides in a subtropical contaminated soil
文章编号: N18091504
期刊: Environmental Science and Pollution Research
作者: Dan Wan, Nichen Zhang, Wenli Chen, Peng Cai, Lirong Zheng, Qiaoyun Huang
更新时间: 2018-09-15
摘要: The bioavailability and potential uptake of heavy metals by crops is fundamentally influenced by the forms of metals in soils. Organic matter plays an important role in controlling the transformation of heavy metal fractionations in soils. However, long-term effects of organic matter on heavy metal speciation remains highly uncertain. In this study, rice straw was introduced to a subtropical Pb-contaminated soil for 2-year period so as to clarify the redistribution of Pb fractions and their correlations with soil properties. By combining sequential extraction and X-ray absorption fine structure spectroscopy, we find that lead is predominantly presented in Fe oxide-bound, surface adsorbed, and residual fractions in the soil. The incorporation of rice straw can effectively reduce the labile species of Pb by promoting the binding of Pb to iron oxides. Furthermore, aging leads to the transfer of considerable amounts of Pb to the association with Fe oxides and this transformation is enhanced by the presence of organic matter. Organic matter input and soil aging tend to shift Pb to amorphous Fe oxides than crystalline Fe oxides. The correlation analysis shows that Fe oxide fractions play vital roles in controlling the forms of Pb in soil. This study presents the first result regarding the long-term effect of organic matter on the redistribution of Pb in naturally polluted soil, which is useful for understanding the fate of Pb and developing remediation strategies for Pb-polluted soils.

17516. 题目: Monovalent-anion Selective and Antifouling Polyelectrolytes Multilayer Anion Exchange Membrane for Reverse Electrodialysis
文章编号: N18091503
期刊: Journal of Membrane Science
作者: Haiping Gao, Bopeng Zhang, Xin Tong, Yongsheng Chen
更新时间: 2018-09-15
摘要: Reverse electrodialysis (RED) is an emerging membrane - based technology that can be used to capture renewable energy released from mixing seawater and river water. When natural waters are used as feed solutions, the presence of multivalent ions and natural organic matter (NOM) results in a lower open circuit voltage (OCV) and power density. In this research, we modified the surface of standard anion exchange membranes (AEMs) via the facile layer-by-layer (LBL) deposition of poly(styrenesulfonate) (PSS) and poly(ethyleneimine) (PEI). Only moderate increase was introduced to the membrane area resistance. The modified membranes exhibited monovalent - anion selectivity comparable to that of commercial monovalent-ion selective membranes, and largely improved anti-organic fouling potential simultaneously. When tested in a RED process with feed waters containing not only chloride but sulfate and humic acid, the maximum gross power density generated was improved by up to 17 % with polyelectrolyte-modified membranes. Also, the energy conversion efficiency of the modified membranes could be prominently increased by 3 times compared with standard AEM conversion. The results indicate significant efficacy of AEMs with polyelectrolyte multilayers on their membrane surface for RED application.
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17517. 题目: Impact of antimicrobial silver nanoparticles on anode respiring bacteria in a microbial electrolysis cell
文章编号: N18091502
期刊: Chemosphere
作者: Basem S. Zakaria, Sajib Barua, Ahmed Sharaf, Yang Liu, Bipro Ranjan Dhar
更新时间: 2018-09-15
摘要: This study assessed the impact of antimicrobial AgNPs (50 mg L−1, 30–50 nm) on the electrocatalytic activity of a mixed-culture anode biofilm enriched with Geobacter species. The current densities and electrochemical kinetics were maintained after exposure to AgNPs in consecutive fed-batch cycles, despite significant changes in morphological structures and bacterial communities. Bacterial community analysis showed a substantial increase in the Geobacter population in response to AgNPs exposure, indicating their higher tolerance to AgNPs. In contrast, the population of other anode respiring bacteria (ARB) belongs to Acinetobacter, Dysgonomonas, and Cloacibacillus genera appeared to be very sensitive to AgNPs toxicity as their relative abundance significantly decreased. Microscopic imaging showed that AgNPs were accumulated within anode biofilm matrix without penetration inside the cells. Moreover, the anode biofilm became denser because of enhanced extracellular polymeric substances (EPSs) production by ARB after exposure of AgNPs, implying that EPS could protect ARB against AgNPs toxicity.
图文摘要:

17518. 题目: Free ammonia-based pretreatment enhances phosphorus release and recovery from waste activated sludge
文章编号: N18091501
期刊: Chemosphere
作者: Qiuxiang Xu, Xuran Liu, Dongbo Wang, Yanxin Wu, Qilin Wang, Yiwen Liu, Xiaoming Li, Hongxue An, Jianwei Zhao, Fei Chen, Yu Zhong, Qi Yang, Guangming Zeng
更新时间: 2018-09-15
摘要: The recovery of phosphorus from waste activated sludge (WAS) was usually at low levels due to low phosphorus release. This study presents a novel, cost-effective and eco-friendly pretreatment method, e.g., using free ammonia (FA) to pretreat WAS, to enhance the phosphorus release from WAS. Experimental results showed that the phosphorus release from WAS was significantly increased after FA pretreatment at up to 189.4 mg NH3-N L−1 for 24 h, under which the released PO43P (i.e. 101.6 ± 6.7 mg L−1) was higher than that pH 9 (i.e. 62.6 ± 4.54 mg L−1) and control (without pH and FA pretreatment) (i.e. 15.1 ± 1.86 mg L−1). More analysis revealed that the FA induced improvement in phosphorus release could be attributed to the disintegration of extracellular polymeric substances (EPS) and cell envelope of sludge cells. Moreover, the released phosphorus recovered as magnesium ammonium phosphate (MAP) was confirmed. The findings reported may guide engineers to develop an economic and practical strategy to enhance resources and energy recovery from WAS.
图文摘要:

17519. 题目: The spatial variability structure of soil attributes using a detailed sampling grid in a typical periglacial area of Maritime Antarctica
文章编号: N18091412
期刊: Environmental Earth Sciences
作者: A. Thomazini, M. R. Francelino, A. B. Pereira, A. L. Schünemann, E. S. Mendonça, C. E. G. R. Schaefer
更新时间: 2018-09-14
摘要: Large spatial variations on soil attributes and vegetation distribution in terrestrial ecosystems occurs in maritime Antarctica. Guano deposition, organic matter accumulation and vegetation coverage, associated with soil drainage conditions, are the main drivers of soil development, varying considerably in time and space. Yet, the spatial variability of soil attributes remains little documented in this region, being constantly altered due to the intense periglacial processes. The objective of this study was to determine spatial variability structure of a representative ice-free area, to understand how changes on landscape, vegetation coverage and biological activity affect soil attribute distribution, using a detailed grid guaranteeing the recognition/representation of the variability range at Keller Peninsula, King George Island, Maritime Antarctica. A representative heterogeneous area was selected in February 2015, where a large variation on the spatial distribution of vegetation and guano occur, in a typical Antarctic periglacial landscape. A 133-point 50 × 50 m grid with a minimum separation distance of 0.5 m was installed, in which sectors were delimited according to guano influence and vegetation cover. Soil was sampled (0–10 cm) at each point of the grid, to map and model the spatial variability of general soil attributes. Principal component analysis (PCA) was used to select the most important soil attributes in this periglacial landscape. Further, experimental semivariograms were calculated and thematic kriging maps obtained, allowing the visual interpretation of the phenomena. Soil attributes significantly (p < 0.05) varied across the delimited sectors. Soil bases (Ca, Mg, K, Na) and physical soil attributes (sand and silt) were the most important variables selected through PCA. We observed that the spatial variability structure of soil attributes is highly influenced by the heterogeneity of ice-free areas in Maritime Antarctica. In periglacial zones where guano is deposited, soil acidification occurs, resulting in high exchangeable Al contents and potential acidity, associated with elevated amounts of organic matter and phosphorus. In this area, the spatial dependence is stronger. The strength of the spatial dependence rapidly decreases out of the influence of guano deposition, where a more heterogeneous environment is observed. Vegetation coverage also altered the spatial variability structure by stabilizing landscape, avoiding nival erosion and enhancing soil nutrient status. Bare soils reveal a more pronounced skeletal character, with low soil nutrient assembly due to the weak nutrient cycling with a great variability across the landscape. Results reported in this study are expected to represent other similar periglacial landscapes in maritime Antarctica.

17520. 题目: Germanium in the soil-plant system—a review
文章编号: N18091411
期刊: Environmental Science and Pollution Research
作者: Oliver Wiche, Balázs Székely, Christin Moschner, Hermann Heilmeier
更新时间: 2018-09-14
摘要: Germanium (Ge) is widespread in the Earth’s crust. As a cognate element to silicon (Si), Ge shows very similar chemical characteristics. Recent use of Ge/Si to trace Si cycles and changes in weathering over time, growing demand for Ge as raw material, and consequently an increasing interest in Ge phytomining have contributed to a growing interest in this previously rather scarcely considered element in geochemical studies. This review deals with the distribution of Ge in primary minerals and surface soils as well as the factors influencing the mobility of Ge in soils including the sequestration of Ge in secondary mineral phases and soil organic matter. Furthermore, the uptake and accumulation of Ge in plants and effects of plant-soil relationships on the availability of Ge in soils and the biogeochemical cycling of Ge are discussed. The formation of secondary soil minerals and soil organic matter are of particular importance for the concentration of Ge in plant-available forms. The transfer from soil to plant is usually low and shows clear differences between species belonging to the functional groups of grasses and forbs. Possible uptake mechanisms in the rhizosphere are discussed. However, the processes that are involved in the formation of plant-available Ge pools in soils and consequently its biogeochemical cycling are not yet well understood. There is, therefore, a need for future studies on the uptake mechanisms and stoichiometry of Ge uptake under field conditions and plant-soil-microbe interactions in the rhizosphere as well as the chemical speciation in different plant parts.

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