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13861. 题目: Thermodynamic stability of methyldibenzothiophenes in sedimentary rock extracts: Based on molecular simulation and geochemical data
文章编号: N18113007
期刊: Organic Geochemistry
作者: Sibo Yang, Meijun Li, Xiaoqiang Liu, Qiuya Han, Jia Wu, Ningning Zhong
更新时间: 2018-11-30
摘要: The thermodynamic stabilities of methyldibenzothiophene(MDBT) isomers and the mechanisms of 1,2-methyl shift, methylation and demethylation have been systematically investigated by molecular modelling. Combining with the geochemical data from a set of lacustrine mudstone samples in the Liaohe Basin (East China), this study reveals the possible reaction mechanisms governing the formation and occurrence of MDBT isomers in source rocks. The Boltzmann distribution of MDBTs in gas, water and cyclohexane was calculated to show the relative thermal stability with the increasing of temperature (burial depth). A total of eight reaction pathways involving in 1,2-methyl shift, methylation and demethylation chemical processes via ionic and free radical reaction, and the transition states and energy barriers are calculated. The results show that three main reaction pathways (P1, P3 and P6) are three possible pathways for the transformation reactions between DBT and MDBTs during the onset of oil generation window to high maturity stages of sedimentary organic matter. The 1,2-methyl shift isomerization (P1) and low concentration of possible precursor (2-mehtylbiphenyl) for 1-MDBT cause the relative low abundance of 1-MDBT isomer during oil generative window. Methylation of DBT with methyl radical attack (P3), the formation of MDBTs with TMAB as methyl donor (P6), the prevailing degradation reactions and much higher thermodynamic stability of 4-MDBT relative to 1-MDBT makes the MDR maturity indicator regularly increase during oil generative window to high maturity stages. Therefore, previously proposed MDR maturity indicator was further confirmed by theoretical calculation, molecular simulation and the geochemical data of the lacustrine mudstone samples in this study.
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13862. 题目: The effect of biochar nanoparticles on rice plant growth and the uptake of heavy metals: Implications for agronomic benefits and potential risk
文章编号: N18113006
期刊: Science of The Total Environment
作者: Le Yue, Fei Lian, Yang Han, Qiongli Bao, Zhengyu Wang, Baoshan Xing
更新时间: 2018-11-30
摘要: The interaction between biochar nanoparticles (nano-BC) and plant roots in the rhizosphere is largely unknown, although it is crucial for understanding the role of BC in plant growth and bioavailability of pollutants. The effect of nano-BC produced at a series of temperatures (300–600 °C) on alleviating the phytotoxicity of Cd2+ to rice plants was investigated from the aspects of biochemical changes and Cd uptake in this study. The kinetics of Cd2+ fluxes in different root zones in the presence of nano-BC were also measured using a scanning ion-selective electrode technique. We found that the high-temperature nano-BC could more significantly alleviate the phytotoxicity of Cd2+ than the low-temperature and bulk BCs as reflected by the higher increased biomass, root vitality, chlorophyll content, and decreased MDA content as well as relative electrical conductivity of rice plants, which is due to the high adsorption affinity of nano-BC for Cd2+. Also, for the first time we demonstrated that nano-BC could differentially affect the net flux of Cd2+ in different zones of the root tips. However, nano-BC (especially that produced at higher temperatures) more significantly increased the contents of antioxidative enzyme activities (e. g., SOD, POD, and CAT) and soluble protein than the treatment only with Cd2+ (5.0 mg/L), indicating that nano-BC could induce oxidative stress in the rice plants. These results indicate that nano-BC could greatly reduce the uptake and phytotoxicity of Cd2+, but its potential risk should not be overlooked during the environmental and agricultural applications of biochar.
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13863. 题目: Synthesis of biochar from chili seeds and its application to remove ibuprofen from water. Equilibrium and 3D modeling
文章编号: N18113005
期刊: Science of The Total Environment
作者: R. Ocampo-Perez, E. Padilla-Ortega, N.A. Medellin-Castillo, P. Coronado-Oyarvide, C.G. Aguilar-Madera, S.J. Segovia-Sandoval, R. Flores-Ramírez, A. Parra-Marfil
更新时间: 2018-11-30
摘要: In this work chili seeds (Capsicum annuum) were used as raw material in the synthesis of biochar at temperatures between 400 and 600 °C. The samples were chemically, texturally and morphologically characterized and their properties were correlated with the calcination temperature. The adsorption mechanism of IBP was elucidated by analyzing the effect of solution pH, ionic strength and temperature, whereas that, the intraparticle diffusion mechanism was clarified through the application of a 3D diffusional model. The results evidenced that raising the pyrolysis temperature promotes a greater content of disordered graphitic carbon (51.6–85.02%) with small surface area (0.52–0.18 m2/g) and low quantity of functional groups. The adsorption study demonstrated that the biochar synthesized at 600 °C (C600) enhances the adsorption capacity >50 folds compared with chili seeds. Moreover, at pH = 7 the adsorption mechanism is governed by π-acceptor and attractive electrostatic interactions, whereas at basic pH the main adsorption mechanism is π-acceptor. Additionally, hydrophobic interactions become important by increasing the presence of NaCl. The application of 3D diffusional model based on surface diffusion interpreted clearly the kinetic curves obtaining values of Ds ranging from 2.31 × 10−8–2.51 × 10−8 cm2 s−1. Besides, it was determined that intraparticle mass flux is larger along the shortest axis of the seed, and always directed toward the particle center. The maximum mass flux takes place in the center of particle, and it advances like a moving front as time was increased.
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13864. 题目: Response of ammonia volatilization to biochar addition: A meta-analysis
文章编号: N18113004
期刊: Science of The Total Environment
作者: Zhipeng Sha, Qianqian Li, Tiantian Lv, Tom Misselbrook, Xuejun Liu
更新时间: 2018-11-30
摘要: There has been increasing interest in and use of biochar as a soil amendment. However, the effects of biochar addition on ammonia volatilization (AV) appeared contradictory from the many reported studies and the main influencing factors remain unclear. Here, we conducted a comprehensive meta-analysis of 41 published articles with 144 observations to reveal the effects of biochar addition on AV and used a boosted regression tree modelling approach to further interpret the contribution of biochar characteristics, soil properties and experimental conditions to this process. On average, biochar addition did not impact on AV, but this varied greatly under different soil, biochar and experimental conditions. The pH of soil and biochar were important factors impacting AV. Biochar application to acidic soil could stimulate AV, and addition of biochar with a high pH and at a low application rate also showed the same trend. In contrast, combining biochar with urea or organic fertilizer, or using wood-based or acidified biochar at appropriate rates had benefits in reducing AV. These findings have major implications for biochar management strategies in agricultural systems, where an important consideration is the mitigation of potentially detrimental environmental consequences.
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13865. 题目: Insight into complexation of Cu(II) to hyperthermophilic compost-derived humic acids by EEM-PARAFAC combined with heterospectral two dimensional correlation analyses
文章编号: N18113003
期刊: Science of The Total Environment
作者: Jia Tang, Li Zhuang, Zhen Yu, Xiaoming Liu, Yueqiang Wang, Ping Wen, Shungui Zhou
更新时间: 2018-11-30
摘要: Hyperthermophilic composting has been demonstrated to overcome the disadvantages of conventional composting in products with better quality. However, the complexation of heavy metals to hyperthermophilic compost (HTC)-derived HA remains unclear. In the present work, using Cu(II) as the representative heavy metal, we investigated the binding process of Cu(II) to HAs derived from HTC, thermophilic compost (TC), and sewage sludge (SS). The complexation ability of three HAs was analyzed by the method of parallel factor (PARAFAC) coupled with hetero two-dimensional correlation spectroscopy (hetero-2DCOS) analyses. Results showed that HTC-derived HA has the greater complexation ability (log KM = 5.68, CCM = 1.21) than both TC-derived HA (log KM = 5.27, CCM = 0.94) and SS-derived HA (log KM = 5.19, CCM = 0.586), likely due to the higher humification degree, as well as the faster response of carboxyl and phenols to Cu(II) binding with HTC-derived HA. This study demonstrated that the utilization of HTC might provide an effective approach for remediation of Cu(II)-polluted soils. Moreover, PARAFAC analysis integrated with hetero-2DCOS offers a unique insight into understanding the correlation between HAs fractions and functional groups during the Cu(II) binding process.
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13866. 题目: Sources and dry deposition of carbonaceous aerosols over the coastal East China Sea: Implications for anthropogenic pollutant pathways and deposition
文章编号: N18113002
期刊: Environmental Pollution
作者: Fengwen Wang, Ting Feng, Zhigang Guo, Yuanyuan Li, Tian Lin, Neil L. Rose
更新时间: 2018-11-30
摘要: 75 paired TSP and PM2.5 samples were collected over four seasons on Huaniao Island (HNI), an island that lies downwind of continental pollutants emitted from mainland China to the East China Sea (ECS). These samples were analyzed for organic carbon (OC) and elemental carbon (EC), with a special focus on char-EC (char) and soot-EC (soot), to understand their sources, and the scale and extent of pollution and dry deposition over the coastal ECS. The results showed that char concentrations in PM2.5 and TSP averaged from 0.13 to 1.01 and 0.31–1.44 μg m−3; while for soot, they were from 0.03 to 0.21 and 0.16–0.56 μg m−3, respectively. 69.0% of the char and 36.4% of the soot were present in PM2.5. The char showed apparent seasonal variations, with highest concentrations in winter and lowest in summer; while soot displayed maximum concentrations in fall and minimum in summer. The char/soot ratios in PM2.5 averaged from 3.29 to 17.22; while for TSP, they were from 1.20 to 7.07. Both of the ratios in PM2.5 and TSP were highest in winter and lowest in fall. Comparisons of seasonal variations in OC/EC and char/soot ratios confirmed that char/soot may be a more effective indicator of carbonaceous aerosol source identification than OC/EC. Annual average atmospheric dry deposition fluxes of OC and EC into ECS were estimated to be 229 and 107 μg m−2 d−1, respectively, and their deposition fluxes significantly increased during episodes. It was estimated that the loadings of OC + EC and EC accounted for 1.3% and 4.1% of the total organic carbon and EC in ECS surface sediments, respectively, implying a relatively small contribution of OC and EC dry deposition to organic carbon burial. This finding also indicates a possibly more important contribution of wet deposition to organic carbon burial in sediments of ECS, and this factor should be considered for future study.
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13867. 题目: Effect of salinity and humic acid on the aggregation and toxicity of polystyrene nanoplastics with different functional groups and charges
文章编号: N18113001
期刊: Environmental Pollution
作者: Jiayi Wu, Ruifen Jiang, Wei Lin, Gangfeng Ouyang
更新时间: 2018-11-30
摘要: Studies regarding the effect of environmental factors on the environmental behaviour and potential toxicity of nanoplastics (NPs) are limited but important. In this study, four polystyrene NPs with different functional groups and charges (PS, PS-COOH, n-PSNH2, p-PSNH2) were selected to investigate the effect of humic acid (HA) and salinity on their aggregation behaviour and toxicity. The results showed that salinity significantly accelerated the aggregation of the four NPs, while HA mainly exerted a stabilizing effect on the three negatively charged NPs. In contrast, the positively charged p-PSNH2 aggregated significantly at first but remained stable as HA concentration further increased. The joint effect mainly depended on their concentration ratio. The aggregation phenomena can be explained by the Derjaguin - Landau - Verwey - Overbeek (DLVO) theory. Also, the acute toxicity of NPs on Daphnia magna was affected by the surface charge of NPs, and the positively charged p-PSNH2 showed the lowest toxicity among the selected NPs. Furthermore, the presence of HA effectively alleviated the toxicity of PS and p-PSNH2, as the survival rates increased from 15% to 45%–95% and 100% respectively. Our results demonstrate that the surface properties of NPs significantly influence their aggregation and toxicity.
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13868. 题目: Distributing sulfidized nanoscale zerovalent iron onto phosphorus-functionalized biochar for enhanced removal of antibiotic florfenicol
文章编号: N18112914
期刊: Chemical Engineering Journal
作者: Jiang Xu, Zhen Cao, Yan Wang, Yilin Zhang, Xiaoyu Gao, Mohammad Boshir Ahmed, Jing Zhang, Yi Yang, John L. Zhou, Gregory V. Lowry
更新时间: 2018-11-29
摘要: Aggregation of nZVI and sulfur-modified nZVI (S-nZVI) can lower its reactivity with contaminants in water. To overcome this limitation, we synthesized biochar-supported nZVI and S-nZVI using a phosphate pretreatment of the biochar (pBC) to uniformly distribute the nZVI and S-nZVI onto the biochar support. The participation of phosphorus groups in the synthesis, and the good distribution of S-nZVI on the pBC were confirmed by FTIR, SEM, XRD, and XPS. Pretreatment of the biochar led to smaller well-dispersed S-nZVI compared to S-nZVI supported on untreated biochar. This increased the surface area of the S-nZVI and the reaction rate with the antibiotic florfenicol (FF). The removal rate of FF by pBC-S-nZVI was 4.3 times higher than that by unsupported S-nZVI. Even though FF strongly adsorbed to the pBC support, FF was fully degraded based on the mass balance results. Surface area normalized reaction rate constants (kSA) for FF removal by S-nZVI, BC-S-nZVI, and pBC-S-nZVI were similar, suggesting that the enhanced reactivity is due to the greater dispersion of S-nZVI on the treated biochar. These results provide a simple pretreatment method for dispersing nZVI or S-nZVI onto biochar supports.
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13869. 题目: Chemostratigraphic resolution of widespread reducing conditions in the southwest Pacific Ocean during the Late Paleocene
文章编号: N18112913
期刊: Chemical Geology
作者: Benjamin R. Hines, Michael F. Gazley, Katie S. Collins, Kyle J. Bland, James S. Crampton, G. Todd Ventura
更新时间: 2018-11-29
摘要: Paleogene strata throughout much of the southwest Pacific is comprised of thick successions of fine-grained siliceous to calcareous sediments. However, during the Late Paleocene the south Pacific experienced widespread deposition of organic-rich and δ13Corg-enriched sediments that are recorded in the Waipawa Formation and the correlative Waipawa Organofacies. The mechanisms responsible for the elevated input and preservation of organic matter are still poorly understood. Using a multi-proxy chemostratigraphic approach we assess paleoceanographic conditions, including paleo-redox states and paleo-productivity of the Waipawa Formation. Eight key sections from the East Coast Basin, New Zealand were sampled and analysed for multi-element geochemistry and bulk pyrolysis. Sedimentological, stratigraphic and chemostratigraphic evidence indicates the south Pacific underwent an abrupt regression event during the Late Paleocene resulting in on-shelf erosion and/or bypassing of continental sourced sediments from the shelf into deeper waters. The change in sediment delivery further increased nutrients and terrestrial organic matter loading to the site of deposition. Coeval excursions in Ti/Zr and Rb/Sr indicate a shift to an aluminosilicate-dominated sediment supply, resulting in a modest increase in marine productivity that cannot account for the anomalous organic matter enrichment. Changes in the hydrogen index show a transition from terrestrial to mixed terrestrial–marine organic matter occurred during the Late Paleocene, in which high concentration of Type II-III kerogens were buried and preserved in association with enhanced water column reducing conditions in deep marine settings. Elevated concentrations of redox-sensitive trace elements (e.g. U, Mo, Fe, S) are consistent with alternating phases of dysoxic to oxic conditions suggesting an expansion of an oxygen minimum zone, enhancing preservation and delivery of organic matter to the seafloor, leading to the subsequent burial and preservation of organic matter within anoxic sediments. These new data provide insight into the depositional conditions and the petroleum potential of prospective source rocks in this basin using an integrated organic and inorganic geochemical approach to refine our knowledge of the depositional environment and paleoceanographic changes in shelfal to bathyal marine sediments of the Late Paleocene.

13870. 题目: Condensate refractory inclusions from the CO3.00 chondrite Dominion Range 08006: Petrography, mineral chemistry, and isotopic compositions
文章编号: N18112912
期刊: Geochimica et Cosmochimica Acta
作者: S.B. Simon, A.N. Krot, K. Nagashima, L. Kööp, A.M. Davis
更新时间: 2018-11-29
摘要: We have found two refractory inclusions in the CO3.00 carbonaceous chondrite Dominion Range (DOM) 08006 that appear to be primary condensates from the early solar nebula. One, inclusion 56-1, contains the first four phases predicted to form by equilibrium gas-solid condensation: corundum; hibonite; grossite; and perovskite. The other, 31-2, contains nine predicted condensate phases: hibonite; grossite; perovskite; melilite; spinel; FeNi metal; diopside; forsterite; and enstatite. Except for melilite/spinel, the phases occur in the predicted sequence from core to rim of the inclusion, which has an irregular shape inconsistent with a molten stage. This inclusion preserves the most complete record of condensation in the early solar nebula that has yet been found. The physical evidence reported here supports equilibrium condensation calculations that predict the observed sequence as well as the assumptions upon which they are based, such as total pressure (∼10–3 atm), bulk system composition (solar), and C-O-H proportions. All phases in both inclusions and the associated ferromagnesian silicates are 16O-rich, with Δ17O between –25 and –20‰, implying that this is the original composition of the vast majority of primary condensates and that 16O-poor compositions observed in many isotopically heterogeneous inclusions are largely due to subsequent isotopic exchange. While the nebula was well-mixed with respect to oxygen isotopic composition, clearly resolved anomalies in Ca and Ti isotopic compositions indicate that some isotopic heterogeneity existed early and was preserved during condensation. Inclusion 31-2 did not incorporate live 26Al and and has nucleosynthetic anomalies in the heavy Ca and Ti isotopes (i.e., δ48Ca=4.3±1.9‰; δ50Ti=8.8±2.0‰). In contrast, inclusion 56-1 has radiogenic 26Mg excesses yielding a (26Al/27Al)0 ratio of (1.0±0.1) × 10–5 and negative nucleosynthetic isotopic anomalies in Ca (δ48Ca=–10.3±4.2‰) and Ti (δ50Ti=–4.3±2.9‰). Thus, it represents a deviation from the mutual exclusivity relationship between 26Al incorporation and large nucleosynthetic anomalies. The reservoirs in which these inclusions formed had similar O-isotopic and different Al-, Ca– and Ti-isotopic compositions, suggesting that while the CAI-forming region was well-mixed with respect to oxygen isotopic composition, clearly resolved anomalies in Ca and Ti isotopic compositions indicate that some isotopic heterogeneity existed and was preserved during condensation.

13871. 题目: Carbon Cycling of Subsurface Organic Matter Recorded in Speleothem 14C Records: Maximizing Bomb-Peak Model Fidelity
文章编号: N18112911
期刊: Geochimica et Cosmochimica Acta
作者: Peter E. Carlson, Jay L. Banner, Kathleen R. Johnson, Richard C. Casteel, Daniel O. Breecker
更新时间: 2018-11-29
摘要: From 1955 to 1963, atmospheric testing of nuclear weapons caused a significant rise in atmospheric radiocarbon activity. This “bomb peak” has been used to calculate turnover rates of organic carbon in soils and other recent sedimentary deposits. Some speleothems contain precise and independently dated records of radiocarbon activity. These records can be used to understand, through inverse modeling, the processes and rates of turnover of subsurface organic carbon in karst regions. This approach is complicated, however, by the contribution of radioactively “dead” carbon to the stalagmite by the dissolution of host-rock limestone or by the respiration of relatively old soil organic matter. Previously published inverse models of the radiocarbon bomb peak in speleothems constrain the dead carbon proportion (DCP, in percent) by comparing measurements of speleothem radiocarbon activity from before the onset of the bomb peak to measurements of coeval atmospheric radiocarbon. This approach precludes modeling of speleothems that began growing after the onset of atmospheric nuclear weapons testing in 1955. Here, we advance the inverse modeling framework to calculate DCP using the entire length of the speleothem record, allowing for the modeling of speleothems that began growing after the initiation of atmospheric nuclear weapons testing. We test the sensitivity and resolution of this model and find that it can precisely resolve the turnover times and relative contributions of subsurface organic matter pools with residence times of less than a decade. The model fails to resolve turnover times or relative contributions of organic matter pools on millennial or greater timescales. These results also hold for the previously published models from which the current model is derived. We find that imprecise estimates of slow-turnover carbon add significant uncertainty to the calculated average age of respired carbon, which is a common metric of subsurface carbon cycling. The high precision and resolution attainable between sub-decadal carbon pools will allow researchers to differentiate the (sub-) annual pool, which is likely dominated by root/rhizosphere respiration, from the 2- to 10-year pools, which is likely dominated by microbial decomposition of labile organic carbon. The high precision attainable in fast-turnover pools also suggests that when there are multiple viable chronological interpretations for the same speleothem, bomb peak models could be used to help select which chronology is most likely to be accurate. This is important for high-resolution (sub-annual) speleothem climate records, where even single-year chronological offsets can result in misleading calibrations to the instrumental record.

13872. 题目: Fouling resistant functional blend membrane for removal of organic matter and heavy metal ions
文章编号: N18112910
期刊: Journal of Environmental Management
作者: C. Lavanya, R. Geetha Balakrishna, Khantong Soontarapa, Mahesh S. Padaki
更新时间: 2018-11-29
摘要: This study investigates the removal of heavy metal ions and humic acid using Cellulose acetate (CA) and Poly (methyl vinyl ether-alt-maleic acid) (PMVEMA) blend membranes. Antifouling properties of blend membranes were also investigated. Flat sheet membranes were prepared by phase inversion technique using different concentrations of CA and PMVEMA. The prepared membranes were characterized and their performance was evaluated by measuring pure water flux, water uptake capacity and humic acid removal. Rejection of humic acid (HA) was observed to be around 97% for all the blend membranes because of electrostatic interactions between the functional groups of HA and blends. The fouling characteristics of the membranes was assessed using HA as a foulant and the antifouling capacity of blend membranes was observed to be greater with a flux recovery ratio of almost 95% when compared to bare CA, commercial CA (TechInc) and other reported CA blends used for HA rejection. Also, the blend membranes were very effective in removing heavy metal ions (Pb2+, Cd2+ and Cr+6) and humic acid simultaneously. Overall, the PMVEMA modified CA membranes can open up new possibilities in enhancing the hydrophilicity, permeability and antifouling properties.
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13873. 题目: Lipid biomarker distributions in Oligocene and Miocene sediments from the Ross Sea region, Antarctica: Implications for use of biomarker proxies in glacially influenced settings
文章编号: N18112909
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Bella Duncan, Robert McKay, James Bendle, Timothy Naish, Gordon N. Inglis, Heiko Moossen, Richard Levy, G. Todd Ventura, Adam Lewis, Beth Chamberlain, Carrie Walker
更新时间: 2018-11-29
摘要: Biomarker-based climate proxies enable climate and environmental reconstructions for regions where other paleoclimatic approaches are unsuitable. The Antarctic Cenozoic record consists of widely varying lithologies, deposited in rapidly changing depositional settings, with large lateral variations. Previous sedimentological and microfossil studies indicate that the incorporation of reworked older material frequently occurs in these sediments, highlighting the need for an assessment of biomarker distribution across a range of depositional settings and ages to assess the role reworking may have on biomarker-based reconstructions. Here, we compare sedimentary facies with the distribution of n-alkanes and hopanoids within a terrestrial outcrop, two glaciomarine cores and a deep sea core, spanning the Late Oligocene to Miocene in the Ross Sea. Comparisons are also made with n-alkane distributions in Eocene glacial erratics and Mesozoic Beacon Supergroup sediments, which are both potential sources of reworked material. The dominant n-alkane chain length shifts from n-C29 to n-C27 between the Late Eocene and the Oligocene. This shift is likely due to changing plant community composition and the plastic response of n-alkanes to climate cooling. Samples from glaciofluvial environments onshore, and subglacial and ice-proximal environments offshore are more likely to display reworked n-alkane distributions, whereas, samples from lower-energy, lacustrine and ice-distal marine environments predominantly yield immature/contemporaneous n-alkanes. These findings emphasise that careful comparisons with sedimentological and paleontological indicators are essential when applying and interpreting n-alkane-based and other biomarker-based proxies in glacially-influenced settings.

13874. 题目: Frequent euxinia in southern Neo-Tethys Ocean prior to the end-Permian biocrisis: Evidence from the Spiti region, India
文章编号: N18112908
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Alan Stebbins, Jeremy Williams, Michael Brookfield, Steven W. Nye, Robyn Hannigan
更新时间: 2018-11-29
摘要: In this study, we reconstruct water-column oxygen availability during the deposition of Late Permian shales (Wuchiapingian to approximately early Changhsingian) using the geochemistry and morphology of sedimentary pyrite (FeS2). Deposition of the shales occurred prior to the end-Permian mass extinction within the southern Neo-Tethys Ocean (Spiti region, Himachal Pradesh, India). We found that the variability of pyritic sulfur to organic carbon (Spyr/Corg) and the pyritic sulfur isotopic composition (δ34Spyr) did not record changes in oxygen availability at Spiti sections. This was due to the removal of original pyritic sulfur by modern oxidative weathering and diagenetic pyrite formation which overwhelmed the original δ34Spyr values. However, pyrite framboid size distributions was a reliable recorder of paleoredox conditions. The degree of oxygen limitation varied with multiple transient euxinic events interrupting a predominantly oxic-dysoxic trend near the top of the Gungri Formation upper member (approximately late Wuchiapingian to early Changhsingian). These transient euxinic intervals provide important insight and regional evidence of environmental stress and instability in the southern Neo-Tethys well prior to the end-Permian mass extinction.

13875. 题目: Release of polycyclic aromatic hydrocarbons from biochar fine particles in simulated lung fluids: Implications for bioavailability and risks of airborne aromatics
文章编号: N18112907
期刊: Science of The Total Environment
作者: Xinlei Liu, Rong Ji, Yu Shi, Fang Wang, Wei Chen
更新时间: 2018-11-29
摘要: Airborne carbonaceous fine particles, such as soot and biochar, represent a significant fraction of air particulate matter and have received widespread concern due to their health effects. Atmospheric carbonaceous particles can contain high concentration of polycyclic aromatic hydrocarbons (PAHs), and may pose significant health risks when carried into respiratory system from inhalation of particulates. In this study, the bioaccessibility of two PAH compounds, phenanthrene and pyrene, bound to biochar fine particles was assessed by examining their release in two simulated lung fluids: Gamble's solution and artificial lysosomal fluid (ALF). We observed that only 0.47 to 0.75% of biochar-bound PAHs were released in the simulated lung fluids, most likely due to the physical entrapment of PAH molecules in the micropore regimes of biochar, resulting in strong desorption hysteresis, even though apparent desorption equilibrium was reached within 30 min, well within the average clearance time of particulate matter in lung system. The inorganic and organic salts in the simulated lung fluids were found to inhibit the release of PAHs by exerting the pore blockage effect and salting-out effect. Moreover, the low molecular weight organic acids (LMWOAs) in the lung fluids further inhibited PAH release by increasing the micropore volume and surface area of biochar fine particles. When taking into account the inhibited release, the estimated carcinogenic risks of biochar-bound PAHs are typically low, even under extreme conditions wherein both biochar concentrations and PAH loadings on biochar are very high. An important implication is that contaminant bioavailability needs to be taken into account when assessing the risks of the contaminants bound to airborne carbonaceous materials.
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13876. 题目: Effects of arbuscular mycorrhizal fungi, biochar and cadmium on the yield and element uptake of Medicago sativa
文章编号: N18112906
期刊: Science of The Total Environment
作者: Fengge Zhang, Mohan Liu, Yang Li, Yeye Che, Yan Xiao
更新时间: 2018-11-29
摘要: The synergistic effects of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on plant growth and heavy metal uptake remain unclear. A pot experiment was carried out to investigate the influence of AMF inoculation, biochar and cadmium (Cd) addition on the growth, nutrient and cadmium uptake of Medicago sativa, as well as soil biological and chemical characteristics. In comparison to the non-Cd pollution treatment, Cd addition significantly decreased mycorrhizal colonization, biomass, and N, P, Ca and Mg contents of shoots and roots in the absence of biochar. Biochar amendment did not increase mycorrhizal colonization at either Cd levels. Regardless of the biochar amendment, AMF inoculation significantly promoted contents of N and P in plant shoots grown in the Cd-contaminated soils. Nevertheless, in the presence of Cd pollution, biochar dramatically elevated the biomass and N, P, K and Ca contents of plant tissues in both AMF inoculation treatments. Biochar addition significantly reduced soil DTPA-extracted Cd. The treatments with AMF inoculation and biochar amendment showed the lowest shoot Cd concentrations and contents, highest plant tissue N and P contents in the Cd addition group. These results suggested that combined use of AMF inoculation and biochar amendment had significant synergistic effects not only on nutrient uptake but also on the reduction in cadmium uptake of alfalfa grown in Cd-polluted soil.
图文摘要:

13877. 题目: Multiple human pressures in coastal habitats: variation of meiofaunal assemblages associated with sewage discharge in a post-industrial area
文章编号: N18112905
期刊: Science of The Total Environment
作者: I. Bertocci, A. Dell'Anno, L. Musco, C. Gambi, V. Saggiomo, M. Cannavacciuolo, M. Lo Martire, A. Passarelli, G. Zazo, R. Danovaro
更新时间: 2018-11-29
摘要: Marine ecosystems are globally threatened by human activities, but some areas, such as those affected by abandoned industrial plants, show an overlap of acute and chronic impacts, which determine a considerable deterioration of their health status. Here we report the results of a research conducted on coastal sewers that discharge their loads in the highly contaminated area of Bagnoli-Coroglio (Tyrrhenian Sea, Western Mediterranean). The sampling area is characterized by heavy industrial activities (a steel plant using coal, iron and limestone) started in 1905 and ceased in 1990, which left widespread heavy metals and hydrocarbon contamination. After taking into account the potential influence of sediment grain size ranges through their inclusion as covariates in the analysis, we tested the potential impact of sewage discharge on the total abundance and multivariate structure of meiofaunal assemblages, as well as on the abundance of single taxa. The organic matter was analysed in terms of total phytopigment and biopolymeric carbon concentrations. Nematoda, Copepoda (including their nauplii), and Tardigrada were the most abundant meiofaunal taxa at all sites, but nematodes did not show a consistent pattern relative to the sewage outfalls. However, the sewer located in the historically most contaminated area showed a minimal abundance of all taxa, including nematodes, while copepods were relatively less abundant at the two southernmost sewers. Comparing the north vs. south site of the sewers, higher meiofaunal abundances were observed in the southward part, likely as a result of the local circulation. The results of this study indicate the general adaptation of meiofauna to multiple stressors (sewage discharge, superimposed to chronic industrial contamination) and its likely modulation by other local processes. They also provide relevant baseline information for future restoration interventions that would take into account the spatial variation of target organisms as needed.
图文摘要:

13878. 题目: Unexpected higher decomposition of soil organic matter during cold fallow season in temperate rice paddy
文章编号: N18112904
期刊: Soil and Tillage Research
作者: Hyo Suk Gwon, Isra Khan Dawar, Young Eun Yoon, Yong Bok Lee, Pil Joo Kim, Hyun Young Hwang
更新时间: 2018-11-29
摘要: In temperate paddy fields, rice is generally cultivated under flooding for 100–140 days during summer season, and thereafter, the soil is left without management under dried soil condition during cold fallow season. In this area rice straw is mostly removed for cattle feeding. Therefore, soil organic carbon (SOC) stock could be decreased with conventional practices, but the seasonal changes of SOC stock have not been evaluated well. To investigate SOC stock changes in temperate rice paddy, two seasonal C balances during rice cropping and fallow season were compared by the net ecosystem C budget (NECB) in the chemical fertilizer (control) and two different green manure treatments for three years. In the control treatment only chemical fertilizer was conventionally fertilized for rice cropping, but maintained without human control during the fallow season. In two green manure treatments, barley and hairy vetch (hereafter, vetch) were cultivated during the fallow season, and their whole biomasses were incorporated before rice transplanting. The conventional soil management with only chemical fertilization decreased small level of SOC stock (minus 0.70–0.84 Mg C ha−1 y−1 of NECB), which was attributed by high harvest removal (approximately 70% of total C input) and mineralized C loss (30%). Cover cropping and its biomass recycling as green manure was effective to increase SOC stock. High C/N ratio of non-leguminous barley produced high biomass yield, and its biomass incorporation significantly increased SOC stock with 1.21–3.43 Mg C ha−1 y−1 of annual NECB. In comparison low C/N ratio of leguminous vetch application increased slightly SOC stock (0.17–1.34 Mg C ha−1 y−1 of NECB), due to low biomass productivity and high mineralized C loss. However, irrespective with fertilization background, approximately 70% of mineralized C loss were occurred during the cold fallow season. Rice grain yields were similar between the control and hairy vetch treatment, but around 10% lower in barley treatment. Conclusively, high C/N ratio of cover crop cultivation during the fallow season could be better to increase SOC stock in mono-rice paddy, but additional nutrient management to increase rice productivity should be developed for barley utilization as green manure.

13879. 题目: A new experimental platform connecting the rhizosphere priming effect with CO2 fluxes of plant-soil systems
文章编号: N18112903
期刊: Soil Biology and Biochemistry
作者: Camille Cros, Gaël Alvarez, Frida Keuper, Sébastien Fontaine
更新时间: 2018-11-29
摘要: Forty years of research on the rhizosphere priming effect (RPE) has demonstrated the potentially large increase (up to a factor 3) of soil organic matter mineralization induced by plant roots, but failed to directly quantify its contribution to the carbon (C) balance. Combining continuous CO2 flux measurements with RPE measurements has thus far been technically challenging. Here, we present an experimental platform of 40 mesocosms (volume = 88L; surface = 0.049 m2), including a 13C-labeled CO2 air-production system with a maximum capacity of 4 m3 min−1 and customizable labeling intensity. For this study, 13C depleted fossil C was used as source of labeled CO2 and the experiment was run for 250 days. Continuous net CO2-exchange measurements allowed us to estimate net ecosystem productivity, gross primary production and ecosystem respiration of the studied plant-soil systems. The RPE was regularly (bi-monthly to monthly) quantified by measuring the accumulation and isotopic composition of CO2 in dark chambers placed over the mesocosms. Our results show a good relationship between night plant-soil respiration (from continuous CO2-exchange measurements) and dark plant-soil respiration (from CO2 accumulation in dark chambers). This result suggests that our estimates of RPE and plant-soil fluxes based on the different methods are comparable. Preliminary results obtained in spring with grasses cultivated under ambient or elevated CO2 indicate that the RPE represents 1.22 ± 0.16% of gross primary production and 4.64 ± 1.12% of ecosystem respiration. The RPE estimates may have an uncertainty linked to the possible deviation in delta 13C between C sources (soil or plant) and released CO2 from these sources. We performed a sensitivity analysis on how the variation in intensity of isotopic labeling (difference in delta 13C between plant and soil) affects the uncertainty of RPE estimates considering 1‰ delta 13C deviation. Estimation of the RPE with an uncertainty lower than 10% of the estimated value requires a labeling intensity higher than 60‰. The developed platform will help to scale up the study of the RPE control on C cycling to the ecosystem level.

13880. 题目: Effects of shrubs on soil nutrients and enzymatic activities over a 0–100 cm soil profile in the desert-loess transition zone
文章编号: N18112902
期刊: CATENA
作者: Yufei Yao, Mingan Shao, Xiaoli Fu, Xiang Wang, Xiaorong Wei
更新时间: 2018-11-29
摘要: The creation of “fertile islands” beneath shrubs in dryland ecosystems has been widely reported worldwide and is the major factor influencing ecosystem structure and function. However, studies investigating whether and how shrubs affect soil biogeochemical cycles in deep soil layers are relatively limited. In this study, we examined the vertical distribution of the soil nutrient contents and enzymatic activities at the 0–100 cm soil profiles beneath three common xerophytic shrubs (Artemisia ordosica, Caragana korshinskii and Salix psammophila) and in interspace bare soils in a transition zone from desert to loess in the north of China. The soil metrics included the contents of organic carbon, total nitrogen, total phosphorus, nitrate and ammonium nitrogen, available phosphorus and potassium, and the activities of saccharase, urease, alkaline phosphatase and amylase. We found that the contents of organic carbon, total nitrogen and available potassium, and the activities of saccharase, urease and alkaline phosphatase were higher in the soils beneath shrubs than in the interspace bare areas, but these differences only occurred in the 0–10 cm soil profile but not in the soils below the depth of 10 cm. The soil quality index was consistently improved among the three shrub species in the topsoil. In addition, the soil nutrients were positively correlated with enzymatic activities, and the organic carbon content explained approximately 50% of the variations in the enzymatic activities. Collectively, our results demonstrated that the establishment of xerophytic shrubs improved the soil chemical and biological conditions in the desert-loess transition region, and the effect was restricted to the 0–10 cm soil layer.

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