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26601. 题目: Enhanced performance and mechanism of bromate removal in aqueous solution by ruthenium oxide modified biochar (RuO₂/BC)
文章编号: N19032809
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Chuanglei Fan, Nan Chen, Chuanping Feng, Yuqing Yang, Jibo Qin, Miao Li, Yu Gao
更新时间: 2019-03-28
摘要: The removal of pollutants from water using agricultural waste-based biomaterials is gaining extensive attention. In this study, biochar loading ruthenium oxide (RuO₂/BC), a novel composite for bromate removal from drinking water, has been prepared by the impregnation method. Based on the single-factor design, a Box-Behnken design (BBD) of the response surface methodology (RSM) was applied to access the mutual interactions and effects between the three factors and optimized preparation conditions (activation time is 3.9 h, activation temperature is 612.2 °C and mass ratio of biochar to RuCl₃ is 38.9: 1). The effects of initial solution pH, RuO₂/BC dosage and initial bromate concentration on bromate removal by RuO₂/BC were investigated. The Field Emission Scanning Electronic Microscopy (FESEM), Brunauer-Emmett-Teller (BET), Energy Dispersive X-Ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and Zeta potential were used to characterize the properties of prepared composite. Results showed that bromate removal by RuO₂/BC was highly pH dependent and the bromate reduction kinetics followed the pseudo-first-order kinetic model. The detailed mechanism including adsorption and reduction of bromate by the synergistic effect of RuO₂ and biochar (C = C, C = O and -OH) was demonstrated. These results proposed a new approach for the remediation of bromate contaminated water.
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26602. 题目: The role of tephra in enhancing organic carbon preservation in marine sediments
文章编号: N19032808
期刊: Earth-Science Reviews
作者: Jack Longman, Martin R. Palmer, Thomas M. Gernon, Hayley R. Manners
更新时间: 2019-03-28
摘要: Preservation of organic carbon (C_org) in marine sediments plays a major role in defining ocean-atmosphere CO₂ levels, Earth climate, and the generation of hydrocarbons. Important controls over sedimentary C_org preservation include; biological productivity, C_org isolation from oxidants (mainly dissolved O₂) in the overlying water column and sediments, and C_org – mineral association in sediments. Deposition of the products of explosive volcanism (tephra) in the oceans directly enhances C_org burial through all these mechanisms, and indirectly through enhanced formation of authigenic carbonate (C_auth) derived from sedimentary C_org. In the modern oceans, it is suggested that tephra deposition may account for 5–10% of the C_org burial flux and 10–40% of the C_auth burial flux. However, during certain periods in Earth's history, extensive explosive volcanism may have led to enhanced C_auth precipitation on a sufficiently large scale to influence the global ocean-atmosphere carbon cycle. Changes in tephra-related C_org preservation may also have played a role in increasing C_org preservation rates in local marine basins, at the oxic-anoxic boundary and enhanced the generation of hydrocarbon deposits in these settings.

26603. 题目: Effects of dissolved organic matter from different sources on Microcystis aeruginosa growth and physiological characteristics
文章编号: N19032807
期刊: Ecotoxicology and Environmental Safety
作者: Miaomiao Zhao, Dong Qu, Wendi Shen, Ming Li
更新时间: 2019-03-28
摘要: The roles dissolved organic matter play when managing watersheds and controlling cyanobacteria blooms have been overlooked. We assessed the effects of dissolved organic matter extracted from biochar, paddy soil, pectin, and rice husks, at carbon concentrations of 0, 1, 3, 5, and 10 mg L⁻¹ on Microcystis aeruginosa growth, photosynthesis, and physiological characteristics. The dissolved organic matter derived from paddy soil and rice husks increased M. aeruginosa growth by promoting photosynthesis. Biochar at low carbon concentrations (1, 3, and 5 mg L⁻¹) also improved M. aeruginosa growth by increasing the maximum photosynthesis II quantum yield. However, biochar at a high concentration decreased the protein and RNA concentrations in M. aeruginosa and therefore inhibited the increase in M. aeruginosa biomass. Pectin did not affect M. aeruginosa photosynthesis, protein concentration, RNA concentration, or growth. The results suggested that M. aeruginosa growth was improved by the amino acids tryptophan and tyrosine, decreased by abundant humic-acid-like substances, and unaffected by polysaccharides.

26604. 题目: Antecedent precipitation influences the bacterial processing of terrestrial dissolved organic matter in a North Carolina estuary
文章编号: N19032806
期刊: Estuarine, Coastal and Shelf Science
作者: C.L. Osburn, J.N. Atar, T.J. Boyd, M.T. Montgomery
更新时间: 2019-03-28
摘要: Estuaries and coastal waters ultimately receive the terrestrial dissolved organic matter (DOM) exported from coastal watersheds, more directly during extreme precipitation events. Recent work suggests DOM's degradation in coastal waters varies with its quality, which also might vary as a function of precipitation, activating contributions from different sources within a watershed. The aim of this study was to determine the extent to which microbial degradation of terrestrial DOM in the Newport River Estuary, eastern North Carolina, was influenced by precipitation events occurring within the preceding seven days from sampling. We hypothesized that DOM stored in forested wetlands (e.g., pocosins and Cypress swamps) that become connected to the main channel of the Newport River during high precipitation events was more labile than DOM flowing into the estuary under low precipitation events. DOM quality was assessed with optical and stable C isotope (δ¹³C) measurements, while DOM lability was assessed by measurements of bacterial production (BP) and mineralization of ¹⁴C-labeled phenanthrene (Pmin), a polyaromatic tracer compound. Aromatic content of DOM, assessed by specific ultraviolet absorbance at 254 nm (SUVA₂₅₄) was highest in the river with values well over 5.0 L mg C⁻¹ m⁻¹, and decreased with salinity. Antecedent precipitation (AP) of at least 100 mm in the seven days prior to sampling resulted in dissolved organic carbon (DOC) concentrations >20 mg L⁻¹, at salinities <10. Similarly, fluorescence humification index (HIX) values were highest in the estuary after the highest AP. Generally depleted δ¹³C-DOC values (−26 to −28‰) in the estuary up to a salinity of 30 indicated a substantial source of DOM likely originating from the forested swamps and tidal wetlands fringing the estuary. BP exhibited wide variability yet declined with salinity, while median values after higher AP (40 μg C L⁻¹ d⁻¹) were double that under lower AP. By contrast, aromatic mineralization (Pmin) rates increased as both DOC and CDOM concentrations, and SUVA₂₅₄ and HIX values, declined with salinity. However, Pmin rates were highest after the highest AP for the three events sampled. Results indicate that flooding of coastal wetlands mobilizes a large pool of labile DOM which have a large impact on the carbon cycle in estuaries. By altering the quality, as well as quantity of terrestrial organic matter inputs to estuarine systems, extreme events may also affect utilization of aromatic organics by estuarine microbial assemblages, an intriguing research question worthy of further study.
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26605. 题目: The importance of macro- and micro-nutrients over climate for leaf litter decomposition and nutrient release in Patagonian temperate forests
文章编号: N19032805
期刊: Forest Ecology and Management
作者: Lucía Vivanco, Amy T. Austin
更新时间: 2019-03-28
摘要: Temperate forests play an important role in the global carbon (C) cycle. Extensive research on litter decomposition in temperate forests in the Northern Hemisphere have greatly contributed to our conceptual framework of the controls of C cycling, where climate and litter lignin/N ratio have played a dominant role. However, there is a noteworthy lack of basic information on southern temperate forests, which have unique characteristics demonstrated by differences in ecosystem functioning and their response to human impact when compared to their northern counterparts. Patagonian forests are the most extensive temperate forests in South America and offer the opportunity to evaluate the importance of climate and litter traits in old growth forests with relatively little human impact. We compared litter decomposition of 10 dominant native tree species and of two non-native tree species (used as common substrates) in two native forests with varying precipitation and tree species composition: a Nothofagus mesic mixed forest (2200 mm MAP) and an Austrocedrus open dry forest (1350 mm MAP). In addition to rainfall, these forest types differed markedly in tree species composition and leaf litter traits that resulted in 1.5 times larger soil carbon and nitrogen pool in Austrocedrus open dry forest and 5 times higher soil inorganic nitrogen than in Nothofagus mesic forests. Nevertheless, decomposition of common litter substrates was similar between both forest types. In contrast, native tree species litter showed up to 10-fold differences in their decomposition rates in a common forest site. Litter mass loss and nitrogen dynamics were strongly associated with magnesium (Mg) and manganese (Mn) content of the litter, respectively. In contrast to dominant control of climate and litter lignin/N, our results demonstrate that native tree species traits may be more important than climate and its effects on plant-soil interactions in Patagonian forests. Our study also highlights the importance of macro- and micro-nutrients (Mg and Mn) in litter that are generally overlooked as determinants of litter decomposition in terrestrial ecosystems. These native Patagonian forests show distinctive controls of litter decomposition compared with other temperate forests of the world. They also highlight the importance of considering how management that affects tree species identity and composition may have far-reaching effects on ecosystem functioning that are currently not being considered.

26606. 题目: Paired bulk organic and individual amino acid δ¹⁵N analyses of bivalve shell periostracum: A paleoceanographic proxy for water source variability and nitrogen cycling processes
文章编号: N19032804
期刊: Geochimica et Cosmochimica Acta
作者: Nina M. Whitney, Beverly J. Johnson, Philip T. Dostie, Katherine Luzier, Alan D. Wanamaker
更新时间: 2019-03-28
摘要: Developing high resolution, well-dated marine proxies of environmental, climatic, and oceanographic conditions is critical in order to advance our understanding of the ocean’s role in the global climate system. While some work has investigated bulk and compound specific stable nitrogen isotopes (δ¹⁵N) in bivalve shells as proxies for environmental variability, the small concentrations of nitrogen found in the organic matrix of the shell calcium carbonate (CaCO₃) makes developing high resolution records challenging. This study investigates the potential of using the bulk and amino acid δ¹⁵N of bivalve periostracum, the protein layer on the outside of the shell, as a proxy archive of nitrogen cycling processes and water source variability.Bulk δ¹⁵N values were measured on the periostracum, aragonitic CaCO₃, and adductor muscle of Arctica islandica shells collected in the Gulf of Maine. Increased variability of isotopic values across growth lines compared to along growth lines support mechanistic reasoning based on growth processes that periostracum is recording changes in δ¹⁵N over the course of the clam’s lifetime (up to 500 years). In addition, the statistically significant relationship between periostracum δ¹⁵N and contemporaneous carbonate δ¹⁵N of the same shell (r= 0.82, p<.0001, n=40) suggests that periostracum preserves a similar δ¹⁵N signal to that preserved in the carbonate. This finding, coupled with the fact that source amino acid δ¹⁵N values of periostracum are similar to that of the adductor muscle and the particulate organic matter (POM) consumed by the clam, suggests that periostracum bulk δ¹⁵N reflect the δ¹⁵N of the clam’s food source. The isotopic offsets between periostracum, carbonate, and adductor muscle δ¹⁵N values are primarily caused by differences in amino acid composition of the different tissue types, as evidenced by isotope mass balance calculations, although may also be related to differences in δ¹⁵N values of the individual amino acids of the different tissue types, especially the trophic amino acids.Compound specific δ¹⁵N analyses of the periostracum of A. islandica shells were used to determine that the calculated trophic position of the clams in this study (1.4±0.4) did not change significantly between 1783 and 1997. Phenylalanine δ¹⁵N values over the last 70 years show similar trends to that of the bulk record, suggesting that changes in bulk δ¹⁵N of that time period are related to changes in baseline δ¹⁵N. Periostracum δ¹⁵N values from shells collected in the western Gulf of Maine have decreased by ∼1‰ since the mid-1920s. This trend (-0.008‰/year) is not statistically different from the trend of previously published δ¹⁵N values of deep-sea corals from the entrance to the Gulf of Maine over the same time period. This coral record has been shown to indicate a shift in water mass source to the region and therefore the similarity between the two records suggest that changes in periostracum δ¹⁵N values are reflecting broader North Atlantic hydrographic changes. Our study introduces a new, high-resolution and absolutely dated paleoceanographic proxy of baseline δ¹⁵N, presenting the opportunity for future reconstructions of aspects of nitrogen cycling and water source changes in the global oceans.

26607. 题目: Early Silurian δ¹³C_org excursions in the foreland basin of Baltica, both familiar and surprising
文章编号: N19032803
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Emma U. Hammarlund, David K. Loydell, Arne T. Nielsen, Niels H. Schovsbo
更新时间: 2019-03-28
摘要: The Sommerodde-1 core from Bornholm, Denmark, provides a nearly continuous sedimentary archive from the Upper Ordovician through to the Wenlock Series (lower Silurian), as constrained by graptolite biostratigraphy. The cored mudstones represent a deep marine depositional setting in the foreland basin fringing Baltica and we present high-resolution data on the isotopic composition of the section's organic carbon (δ¹³C_org). This chemostratigraphical record is correlated with previously recognized δ¹³C excursions in the Upper Ordovician–lower Silurian, including the Hirnantian positive isotope carbon excursion (HICE), the early Aeronian positive carbon isotope excursion (EACIE), and the early Sheinwoodian positive carbon isotope excursion (ESCIE). A new positive excursion of high magnitude (~4‰) is discovered in the Telychian Oktavites spiralis Biozone (lower Silurian) and we name it the Sommerodde Carbon Isotope Excursion (SOCIE). The SOCIE appears discernible in δ¹³C_carb data from Latvian and Estonian cores but it is not yet widely recognized. However, the magnitude of the excursion within the deep, marine, depositional setting, represented by the Sommerodde-1 core, suggests that the SOCIE reflects a significant event. In addition, the chemostratigraphical record of the Sommerodde-1 core reveals the negative excursion at the transition from the Aeronian to Telychian stages (the ‘Rumba low’), and suggests that the commencement of the EACIE at the base of the Demirastrites triangulatus Biozone potentially is a useful chemostratigraphical marker for the base of the Aeronian Stage.

26608. 题目: Patterns and drivers of meiofaunal assemblages in the canyons Polcevera and Bisagno of the Ligurian Sea (NW Mediterranean Sea)
文章编号: N19032802
期刊: Progress in Oceanography
作者: L. Carugati, M. Lo Martire, R. Danovaro
更新时间: 2019-03-28
摘要: Meiofaunal abundance, assemblage structure and richness of higher taxa were investigated for the first time in two submarine canyons (Polcevera and Bisagno) of the Ligurian Sea and on the adjacent open slope, in relation with the quantity and quality of sedimentary organic matter and other environmental variables, including grain size. Meiofaunal abundance and richness of higher taxa decreased with increasing water depth (from ca. 200 down to ca. 2000-m depth) in the open slope and Polcevera canyon, whereas the highest values were observed at 500 m depth in the Bisagno canyon. The comparison between canyons and the adjacent open slope, showed the lack of significant differences in meiofaunal abundance, at the same depth except for samples collected at 200 and 2000-m depth. Overall the biodiversity was higher in canyons than in the open slope. Phytopigments, utilised as a proxy of the input of primary organic matter, were up to 3 times higher in canyon than in slope sediments and, along with grain size, explained a large portion of the variability in all meiofaunal variables. Canyon and slope showed a high beta diversity (83%), mostly due to the presence of a high portion of rare taxa in the canyons. Some taxa, such as Cladocera, Cumacea, Gastrotricha, Nemertina were exclusively encountered in canyon sediments, whereas Tardigrada were encountered only in the adjacent slope. Results reported here indicated that, differences in meiofaunal assemblages between canyons and slopes are primarily driven by quantity and quality of the available food resources and by the presence of specific topographic features.

26609. 题目: Food web structure and trophodynamics of deep-sea plankton from the Bari Canyon and adjacent slope (Southern Adriatic, central Mediterranean Sea)
文章编号: N19032801
期刊: Progress in Oceanography
作者: I. Conese, E. Fanelli, S. Miserocchi, L. Langone
更新时间: 2019-03-28
摘要: Zooplankton represent a key component of deep-sea ecosystems, linking Particulate Organic Matter (POM) to higher trophic levels through both vertical migrations from the photic zone and being prey of several megafaunal species, including demersal and benthopelagic organisms. Nevertheless, this key group in deep-sea ecosystems is far to be well known, especially concerning trophic aspects. In this study, we aimed to depict the trophic web structure of deep-sea zooplankton collected in sediment traps from the Southern Adriatic, central Mediterranean Sea, and adjacent slope from 600 to 1200 m, and its trophodynamics. To achieve these objectives, we considered a long time-series set of samples, from March 2010 to October 2012 and we used stable isotope analysis of nitrogen and carbon. The area is characterised by cascading events of dense shelf waters, and the possible influence of this periodic phenomenon on seasonal changes in the isotopic composition of deep-sea zooplanktonic species was also analysed. Our results evidenced a complex structure for the deep-sea zooplankton food web with taxa organized in three trophic levels from POM feeders to ultra-specialized carnivores. Temporal changes in the isotopic signatures of deep-sea zooplankton species were observed, although the influence of cascading events was not so clear. The high swimming capability of deep-sea zooplankton and their ability to perform vertical migrations may be the cause of such unclear relationship, with species more relying on vertical fluxes from surface primary production than on lateral advective transport of organic particles.

26610. 题目: Stabilization of Lead and Copper in a Contaminated Typic Torripsament Soil Using Humic Substances
文章编号: N19032716
期刊: Clean - Soil, Air, Water
作者: Ahmed S. Abuzaid, Mohamed A. Bassouny, Hossam S. Jahin, Ahmed A. Abdelhafez
更新时间: 2019-03-27
摘要: Potassium humate (KH) has been known as an effective metal stabilizer. Thus, contaminated soils amended with KH can be implied in horizontal expansion of forage maize to diminish the shortage in summer forage crops in Egypt. The implications of KH on the bioavailability, uptake and accumulation of lead (Pb) and copper (Cu) in maize plants grown on a contaminated soil are investigated. A pot experiment is conducted using a typic Torripsament soil naturally contaminated with Pb and Cu and treated with KH at rates of 0.0, 0.5, 1.0, and 2.0 g kg−1 soil. The KH applications decrease the diethylene triamine pentaacetic acid and water‐extractable Pb and Cu significantly and accordingly decrease their contents in maize shoots and roots compared with control treatment. The highest KH rate of 2.0 g kg−1 soil lower Pb concentration in maize shoots below the safe limit for animal feeding (5 mg kg−1). On the other hand, the KH applications could not achieve a significant reduction of bioavailable Cu and the contents in maize remained far away from the safe limit (4–15 mg kg−1). These findings prove the success of KH in restricting Pb transfer to food chain via maize uptake, while further work with higher application rates is recommended for Cu.

26611. 题目: Molecular marker study of aerosols in the northern South China Sea: Impact of atmospheric outflow from the Indo-China Peninsula and South China
文章编号: N19032715
期刊: Atmospheric Environment
作者: Xiaofei Geng, Guangcai Zhong, Jun Li, Zhineng Cheng, Yangzhi Mo, Shuduan Mao, Tao Su, Haoyu Jiang, Kaiwen Ni, Gan Zhang
更新时间: 2019-03-27
摘要: Continental outflow influences concentration and chemical composition of marine aerosols, which has an important impact on regional biogeochemistry and climate. Aerosols sampling for molecular marker study was conducted from June 2015 to May 2016 at Xieyang Island in the northern South China Sea (SCS), to learn the impact of outflow from Indo-China Peninsular (ICP) and South China (SC). Xieyang Island was under the influence of air masses from ICP and SC nearly 70% of the year. Levels of anhydrosugars were higher during October to early March. They were lower in April and May, although biomass burning events in ICP were most intensive and half of air masses back trajectories passed through ICP in this period. Significant correlations between levels of anhydrosugars, polycyclic aromatic hydrocarbons, n-alkanes, high molecular weight n-fatty acids and terephthalic acid were observed, suggesting co-emissions of these compounds. Source types of aerosol primary organic matter (POM) tracked by these markers, namely open burning of municipal wastes, fossil fuel combustion, higher plant emissions and biomass burning, largely contributed in fall and winter with SC to be an important source region. However, levels of sugar alcohols (a group of biogenic aerosol tracers) were higher in warm seasons with ICP and SCS to be the main source regions, and were poorly correlated with levels of other molecular markers. Carbon preference index of n-alkanes also increased in warm seasons, indicating enhanced higher plant wax emissions. It suggested that there was a close link between biogenic emissions of sugar alcohols (or n-alkanes) and the growing activities of related organisms. Besides continental outflow, there were marine sources of steranes, hopanes (fossil sources tracers) and mannitol (a sugar alcohol), since their levels were higher for aerosol samples basically influenced by air masses originated from SCS.

26612. 题目: Role of biochar and plant growth promoting rhizobacteria to enhance soil carbon sequestration—a review
文章编号: N19032714
期刊: Environmental Monitoring and Assessment
作者: Rubab Sarfraz, Azhar Hussain, Asma Sabir, Ibtissem Ben Fekih, Allah Ditta, Shihe Xing
更新时间: 2019-03-27
摘要: Global climate is undergoing significant changes due to extensive release of greenhouse gases (GHGs) such as CO₂ and methane in the atmosphere. These gases are produced and released as a result of anthropogenic activities and fossil fuel burnings which also result in depletion of soil carbon resources. Biochar has various distinctive properties, which contribute to make it an effective, economical, and eco-friendly approach for soil carbon sequestration. The versatility in physicochemical properties of biochar provides an opportunity to optimize its efficacy to obtain desired benefits. A critical review of the literature indicates that biochar and plant growth–promoting microbes have the potential to improve soil organic carbon (SOC). Recent studies have depicted a significant role of the combined application of plant growth–promoting microbes and biochar on SOC dynamics. In future, these areas need to be explored as these have the potential to improve SOC dynamics and it could be a better strategy to sustain natural resources and ultimately mitigation of the climate change.

26613. 题目: Feasibility of the solar/chlorine treatment for lipid regulator degradation in simulated and real waters: The oxidation chemistry and affecting factors
文章编号: N19032713
期刊: Chemosphere
作者: Liping Wang, Jingyun Fang, Xiang Zhang, Xibing Xu, Xiujuan Kong, Zihao Wu, Zhechao Hua, Ziran Ren, Kaiheng Guo
更新时间: 2019-03-27
摘要: This work investigated the feasibility and mechanisms of solar/chlorine process in the removal of a kind of emerging contaminants, lipid regulators (gemfibrozil (GFRZ), benzafibrate (BZF), and clofibric acid (CA)), in simulated and real waters. These lipid regulators could be effectively removed by solar/chlorine treatment, and their corresponding pseudo-first-order rate constants (k′) increased with increasing chlorine dosage. The degradation of GFRZ and BZF was primarily ascribed to reactive chlorine species (RCS) and ozone, while that of CA was mainly attributable to hydroxyl radical (HO) and ozone. As pH rose from 5.0 to 8.4, k_ozone′ of GFRZ and BZF increased, while k_HO′ decreased. However, k_RCS′ of GFRZ increased by 130%, while that of BZF decreased by 43.3%. These changes resulted in slight changes in the overall k′s with increasing pH. k′s of GFRZ, BZF, and CA by solar/chorine treatment were inhibited by natural organic matter (NOM) while the presence of bromide enhanced the degradation of GFRZ by solar/chlorine process. The degradation of lipid regulators was still effective in a secondary wastewater effluent sample and a sand-filtered water sample, although that was inhibited due to the dissolve organic matter (DOM) contained in real waters. The acute toxicity during the degradation of GFRZ by solar/chlorine treatment was comparable to that by treatment with chlorine alone. This study demonstrated that RCS played an important role in the degradation of micropollutants by the solar/chlorine treatment and the feasibility of solar/chlorine process in the application for the degradation of organic compounds in real waters.
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26614. 题目: Binding characteristics of heavy metals to humic acid before and after fractionation by ferrihydrite
文章编号: N19032712
期刊: Chemosphere
作者: Yang Ding, Minqin Liu, Shimeng Peng, Junhui Li, Yuzhen Liang, Zhenqing Shi
更新时间: 2019-03-27
摘要: The fractionation of humic substances (HS) at the mineral and water interface can change the constituents and reactivity of HS, but there is still a lack of the understanding of the effects of HS fractionation on the binding characteristics of heavy metals to HS. In this study, the binding characteristics of five heavy metals (Cd, Cu, Ni, Pb, and Zn) to humic acid (HA) before and after adsorption by ferrihydrite were investigated by employing two-dimensional correlation spectroscopy (2D COS) integrated with synchronous fluorescence and Fourier transform infrared (FTIR) spectroscopies. 2D COS analyses of the fluorescence results indicated that the susceptibility of the fluorescence of humic-like fraction to heavy metals significantly decreased after the adsorption of HA by ferrihydrite, which may be due to the fact that humic-like components were preferentially adsorbed by ferrihydrite. However, the fractionation processes did not alter the metal binding sequence and affinity to different HA components. 2D COS analyses of the FTIR results suggested that fractionation processes decreased the susceptibility of COO⁻ groups to heavy metals, and changed the metal binding sequence to polysaccharides C-O and aryl groups, with the exception of Pb. Furthermore, model calculations showed that the binding ability of heavy metals to both humic-like and fulvic-like fractions decreased after the adsorption of HA by ferrihydrite. The results of this study contribute to predicting heavy metal behavior in the environment.
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26615. 题目: Interactions of trace elements and organic ligands in seawater and implications for quantifying biogeochemical dynamics: A review
文章编号: N19032711
期刊: Earth-Science Reviews
作者: Jing Zhang, Gerhard Kattner, Boris P. Koch
更新时间: 2019-03-27
摘要: Interactions between dissolved trace elements and organic ligands in seawater play an important role in ocean biogeochemistry, ranging from regulating primary production in surface waters to element cycling on basin-wide scale, with strong feedbacks to climate variability. In this study, we review different aspects in the field of marine trace elements and their organic ligands: recent instrumental innovation, factors that affect the fate of trace element complexes at the molecular level, spatial distribution of organic matter – trace element complexes in the ocean, modeling approaches as well as prospect in the scenarios of climate variability. We also assess the critical issues of parameterization in the numerical simulation that incorporate the trace elements – organic ligands interactions. Given the predicted climate changes, we examine the potential of exchange between inorganic and organic complexes for trace elements in different oceanic provinces.

26616. 题目: Effects of eutrophication on sedimentary organic carbon cycling in five temperate lakes
文章编号: N19032710
期刊: Biogeosciences
作者: Annika Fiskal, Longhui Deng, Anja Michel, Philip Eickenbusch, Xingguo Han, Lorenzo Lagostina, Rong Zhu, Michael Sander, Martin H. Schroth, Stefano M. Bernasconi, Nathalie Dubois, and Mark A. Lever
更新时间: 2019-03-27
摘要: Even though human induced eutrophication has severely impacted temperate lake ecosystems over the last centuries, the effects on total organic carbon (TOC) burial and mineralization are not well understood. We study these effects based on sedimentary records from the last 180 years in five Swiss lakes that differ in trophic state. We compare changes in content of TOC and modeled TOC accumulation rates through time to historical data on algae blooms, water column anoxia, wastewater treatment, artificial lake ventilation, and water column phosphorus (P) concentrations. We furthermore investigate the effects of eutrophication on rates of microbial TOC remineralization and vertical distributions of microbial respiration reactions in sediments. Our results indicate that the history of eutrophication is well reflected in the sedimentary record. Subsurface peaks in sedimentary TOC coincide with past periods of elevated P concentrations in lake water. Sediments of eutrophic lakes show overall higher rates of microbial respiration, and a higher relative contribution of methanogenesis to total respiration. Yet, a clear impact of lake trophic state on the zonation of microbial respiration reactions is absent. Moreover, even though water column P concentrations have been reduced by ~ 80 % (range: ~ 50–90 %) since the period of peak eutrophication in the 1970s, TOC burial and accumulation rates have only decreased significantly (~ 20 and 25 %) in two of the five lakes. Hereby we found no clear relationship between the magnitude of the decrease in P concentrations and the change in TOC burial and accumulation rate. Instead, artificial lake ventilation, which is used to prevent water column anoxia in eutrophic lakes, may help sustain high rates of TOC burial and accumulation in sediments despite strongly reduced water column P concentrations. Our results provide novel insights into how eutrophication and eutrophication management practices affect organic carbon burial and the distribution of microbial respiration reactions in temperate lakes. These insights are important to understanding how anthropogenic activities affect the size of the carbon pool that is stored globally in lacustrine sediments.

26617. 题目: Interactive effects of biochar and AMF on plant growth and greenhouse gas emissions from wetland microcosms
文章编号: N19032709
期刊: Geoderma
作者: Jin-Feng Liang, Jing An, Jun-Qin Gao, Xiao-Ya Zhang, Ming-Hua Song, Fei-Hai Yu
更新时间: 2019-03-27
摘要: Both biochar and arbuscular mycorrhizal fungi (AMF) can affect plant growth, but little is known about how the interaction between biochar and AMF affects greenhouse gas emissions from plant-soil systems. We tested the hypotheses that biochar and AMF can interact to affect greenhouse gas emissions due to promoted plant biomass and changed soil N availability. We assembled microcosms, each initially grown with three ramets (vegetative individuals) of a clonal, wetland plant Phragmites australis, with or without AMF in soil and with or without biochar addition to soil. Biochar addition alone and AMF presence alone both significantly enhanced biomass of P. australis, but such effects became weaker when they were present simultaneously. The presence of AMF significantly decreased concentrations of chlorophyll and nitrogen (N) in P. australis and concentrations of NH₄⁺-N, NO₃⁻-N, inorganic N and total N in soil, but such effects became weaker when biochar was added to soil than when it was not. Biochar addition significantly increased concentrations of chlorophyll and N in P. australis when AMF were present, but had little impact when AMF were absent. The presence of AMF increased CO₂ emission and CO₂ equivalent independent of biochar addition. The presence of AMF also increased N₂O emission when biochar was added, but decreased it when biochar was not added. We conclude that biochar addition and AMF presence can interact to affect plant growth and N uptake, soil N availability and greenhouse gas emissions from plant-soil ecosystems.

26618. 题目: Cerium-modified biochar: A recycling biomaterial for regulating phosphorus availability in paddy ecosystem from coastal mudflat reclamation
文章编号: N19032708
期刊: Geoderma
作者: Haiying Lu, Yanfang Feng, Yuanyuan Feng, Yue Dong, Haijun Sun, Jincheng Xing, Hongbo Shao, Lihong Xue, Linzhang Yang
更新时间: 2019-03-27
摘要: Phosphorus (P) is a vital element for plant growth, especially in mudflat-reclaimed soil due to its extra alleviation of adverse effect by salt stress. P availability in mudflat-reclaimed soil is a critical factor for crop yield. In this study, cerium-modified straw biochar (Ce-MSB) derived from maize straw was prepared and characterized and its influence on P availability of the paddy soil was evaluated. The results indicated that the cerium elements were chemically bound to the functional groups of the biochar surface through SEM, EDX and FTIR techniques. The equilibrium process of P by Ce-MSB was described well by the Langmuir isotherm model (R² > 0.99). The maximal P adsorption capacity of Ce-MSB was influenced remarkably by temperature. Accordingly, the addition of Ce-MSB significantly decreased the P content of surface water in paddy system after 3 months, while increasing the soil P availability. Furthermore, the incorporation of both common biochar and Ce-MSB into the soil increased the SOM content, while decreased soil pH and EC. Biolog EcoPlateTM trials indicated that Ce-MSB has no significantly negative effects on soil microbial diversity. This study provides valuable information for the source-reduction of P discharge from paddy system and improvement of P availability.Phosphorus (P) is a vital element for plant growth, especially in coastal reclaimed mudflat due to its extra alleviation of adverse effect by salt stress. P availability in mudflat-reclaimed soil is a critical factor for crop yield. In this study, cerium-modified straw biochar (Ce-MSB) derived from maize straw was prepared and characterized and its influence on P availability of the paddy soil was evaluated. The results indicated that the cerium elements were chemically bound to the functional groups of the biochar surface through scanning electron microscopy (SEM), energy dispersive X-ray spectrum scanning (EDX), and fourier transform infrared spectroscopy (FTIR) techniques. The equilibrium process of P (PO₄³⁻) by Ce-MSB was described well by the Langmuir isotherm model (R² > 0.99). The maximal P adsorption capacity of Ce-MSB was influenced remarkably by temperature, which was 58, 69, and 78 mg g⁻¹ under 5, 25, and 40 °C, respectively. Under laboratory simulation, the addition of Ce-MSB significantly decreased the P content of surface water in paddy system after 3 months, while increasing the P availability of soil. Furthermore, the incorporation of both common biochar and Ce-MSB into the soil increased the SOM content, while decreased soil pH and EC. Biolog EcoPlateTM trials indicated that Ce-MSB has no significantly negative effects on soil microbial diversity. This study provides valuable information for the source-reduction of P discharge from paddy system and improvement of P availability.

26619. 题目: Aerosol optical properties and the mixing state of black carbon at a background mountainous site in Eastern China
文章编号: N19032707
期刊: Journal of Environmental Sciences
作者: Liang Yuan, Yan Yin, Hui Xiao, Jian Hao, Kui Chen, Xingna Yu, Xiaoling Zhang
更新时间: 2019-03-27
摘要: In-situ measurements of aerosol optical properties were conducted at Mt. Huang from September 23 to October 28, 2012. Low averages of 82.2, 10.9, and 14.1 M/m for scattering coefficient (σ_{sp, neph, 550}), hemispheric backscattering coefficient (σ_{hbsp, neph, 550}), and absorption coefficient (σ_{ap, 550}), respectively, were obtained. Atmospheric aging process resulted in the increase of σ_{ap, 550} but the decrease of the single scattering albedo (ω₅₅₀) at constant aerosol concentration. However, the proportion of non-light-absorbing components (non-BCs) was getting higher during the aging process, resulting in the increase of aerosol diameter, which also contributed to relatively higher σ_{sp, neph, 550} and ω₅₅₀. Diurnal cycles of σ_{sp, neph, 550} and σ_{ap, 550} with high values in the morning and low values in the afternoon were observed closely related to the development of the planetary boundary layer and the mountain-valley breeze. BC mixing state, represented by the volume fraction of externally mixed BC to total BC (r), was retrieved by using the modified Mie model. The results showed r reduced from about 70% to 50% when the externally mixed non-BCs were considered. The periodical change and different diurnal patterns of r were due to the atmospheric aging and different air sources under different synoptic systems. Local biomass burning emissions were also one of the influencing factors on r. Aerosol radiative forcing for different mixing state were evaluated by a “two-layer-single-wavelength” model, showing the cooling effect of aerosols weakened with BC mixing state changing from external to core-shell mixture.
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26620. 题目: Effects of packing carriers and ultrasonication on membrane fouling and sludge properties of anaerobic side-stream reactor coupled membrane reactors for sludge reduction
文章编号: N19032706
期刊: Journal of Membrane Science
作者: Yue Zheng, Zhen Zhou, Cheng Cheng, Zhiwei Wang, Hongjian Pang, Lingyan Jiang, Lu-Man Jiang
更新时间: 2019-03-27
摘要: The aim of this study was to investigate membrane fouling performance of anaerobic side-stream reactor (ASSR) coupled membrane reactors (MBR), and effects of representative enhancement strategy, namely packing carriers and low-strength ultrasonication, on sludge properties and membrane fouling by four pilot-scale MBRs. Compared to anoxic/oxic MBR (AO-MBR) for control, ASSR coupled AO-MBR (ASSR-MBR), ASSR-MBR with ASSR packed with carriers (AP-MBR) and AP-MBR with part of sludge ultrasonicated before fed into ASSR (AUP-MBR) reduced sludge production by 8.4%, 17.5% and 32.9% with efficient pollutants removal. ASSR-MBR showed more severe membrane fouling because inserting ASSR disintegrated sludge floc structure, increased the secretion of extracellular polymeric substances (EPS) and deteriorated viscoelastic property of sludge. Packing carriers in ASSR alleviated membrane fouling of ASSR-MBR by inhibiting EPS-secreting bacteria (Flavobacteriia, γ-Proteobacteria, δ-Proteobacteria and norank_Saccharibacteria), enlarging particle size and improving dewaterability. AUP-MBR showed the most severe membrane fouling and obvious cake layer fouling because ultrasonication disintegrated sludge to small particles, increased adherence property of EPS, and deteriorated dewaterability and viscoelastic property of sludge. MiSeq sequencing revealed Proteobacteria and Bacteroidetes were responsible for membrane fouling at the phylum level, and norank_Neisseriaceae, Arcobacter, norank_Parcubacteria and Mycobacterium were dominant genera easily attached on membrane surface.
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