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22801. 题目: Effects of biochar on uptake, acquisition and translocation of silver nanoparticles in rice (Oryza sativa L.) in relation to growth, photosynthetic traits and nutrients displacement
文章编号: N19042904
期刊: Environmental Pollution
作者: Qumber Abbas, Guijian Liu, Balal Yousaf, Muhammad Ubaid Ali, Habib Ullah, Rafay Ahmed
更新时间: 2019-04-29
摘要: Rapid development in nanotechnology and incorporation of silver nanoparticles (AgNPs) in wide range of consumer products causing the considerable release of these NPs in the environment, leading concerns for ecosystem safety and plant health. In this study, rice (Oryza sativa) was exposed to AgNPs (0, 100, 200, 500 and 1000 mg L⁻¹) in biochar amended (2 %w/v) and un-amended systems. Exposure of plants to AgNPs alone reduced the root and shoot length, biomass production, chlorophyll contents, photosynthesis related physiological parameters as well as macro-and micronutrients in a dose dependent manner. However, in case of biochar amendment, physiological parameters i.e., net photosynthesis rate, maximum photosynthesis rate, CO₂ assimilation, dark respiration and stomatal conductance reduced only 16, 6, 7, 3 and 8%, respectively under AgNPs exposure at 1000 mg L⁻¹ dose. Meanwhile, biochar at all exposure level of AgNPs decreased the bioaccumulation of Ag in rice root and shoot tissues, thus alleviated the phyto-toxic effects of NPs on plant growth. Moreover, results showed that biochar reduced the bioavailability of AgNPs by surface complexation, suppressing dissolution and release of toxic Ag⁺ ions in the growth medium. The presence of biochar at least decreased 2-fold tissue contents of Ag even at highest AgNPs (1000 mg L⁻¹) concentration. These finding suggested that biochar derived from waste biomass resources can be used effectively to prevent the bioaccumulation and subsequent trophic level transfer of emerging Ag nano-pollutant in the environment.
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22802. 题目: Removal and simultaneous reduction of Cr(VI) by organo-Fe(III) composites produced during coprecipitation and coagulation processes
文章编号: N19042903
期刊: Journal of Hazardous Materials
作者: Kai-Yue Chen, Yu-Min Tzou, Ya-Ting Chan, Jeng-Jzung Wu, Heng-Yi Teah, Yu-Ting Liu
更新时间: 2019-04-29
摘要: Composites formed during the coprecipitation and/or coagulation of ubiquitous dissolved organic matter (DOM) and Fe in natural and waste water systems might be potential scavengers for Cr(VI) in terms of sorption and reduction. Our objective here was to determine sorption and simultaneous reduction of Cr(VI) on organo-Fe(III) composites (OFC) in relation coprecipitated pH and C/(C + Fe) ratios. Results showed the greatest Cr sorption of 51.8 mg g^-1 on the OFC sample that was precipitated at pH 3 and contained the C/(C + Fe) molar ratio of 0.71. Wherein the Cr(VI) removal subsequent to the coprecipitation was dominated by the sorption on Fe hydroxides. Although amounts of total sorbed Cr decreased with increasing C/(C + Fe) molar ratio, the reverse trend on Cr(VI) reducibility compensated the Cr(VI) removal capability of OFC samples. With C/(C + Fe) molar ratios ≥ 0.89, the increasing amounts of coprecipitated organic matter that homogeneously distributed with Fe domains on OFC surfaces could trigger a significantly pronounced Cr reduction. Collectively, our results suggested an alternative method for Cr(VI) remediation by manipulating C/Fe ratios in suspensions. After the sorption of most Cr(VI) on Fe hydroxides, increasing C/Fe ratio in systems could further improve the Cr(VI) removal efficiency by the reduction of remaining Cr(VI) to Cr(III).
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22803. 题目: Formation and evolution of the Ediacaran to Lower Cambrian black shales in the Yangtze Platform, South China
文章编号: N19042902
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Xinyan Fang, Liangliang Wu, Ansong Geng, Qian Deng
更新时间: 2019-04-29
摘要: Black shales in the Ediacaran Doushantuo Formation (predominantly from Member II, IV and equivalent strata) and the Lower Cambrian Niutitang Formation (or equivalents) occur widely in the Yangtze Platform, South China. These black shales could provide sufficient hydrocarbons for the petroleum system in this region. However, biomarker parameters have proven invalid in the assessment of petroleum resources because of the high thermal maturity. Therefore, it is necessary to study the characteristics and formation mechanisms of these two black shales. This study analyzed redox-sensitive elements, total organic carbon (TOC) contents, and carbon isotopic compositions of organic matter in four continuous sedimentary successions including the two investigated shales in the Yangtze Platform (namely Jiulongwan on the inner shelf, Songlin in an intra-shelf lagoon, Dongkanshang on the upper slope, and Fengtan in the basin). Combined with other previously reported five sections, the redox conditions of sedimentary waters and marine paleoproductivity of the Ediacaran to Lower Cambrian black shales in the Yangtze Platform were discussed and compared. The results showed that the redox conditions of the Early Cambrian in the study area were similar to those of the Ediacaran Doushantuo period, which were oxic-suboxic at surface water, and anoxic in the deep with the occurrence of euxinic conditions. However, the euxinic conditions in the deep waters were distributed more widely in the Early Cambrian than in the Ediacaran period. The source of organic matter in the Doushantuo Formation was dominated by algae in the shallow-water platform and the shelf-margin areas, while chemoautotrophic/methanotrophic biomass may also have contributed in the intra-shelf lagoon and deep-water basin areas. In contrast, the organic matter of the Niutitang Formation was mainly contributed by the chemoautotrophic/methanotrophic biomass, with a minor contribution by photosynthetic algae and cyanobacteria. During the Doushantuo period, the input of terrigenous clastic materials was low, resulting in the enrichment of organic matter and formation of organic-rich black shale in the Yangtze Platform over a long geological time period. Compared to the Doushantuo period, the shorter sedimentation time and the higher deposition rate during the Early Cambrian produced a thicker and higher-quality Niutitang Formation source rock widely distributed in the Yangtze Platform.

22804. 题目: Investigation of the fouling behaviors correlating to water characteristics during the ultrafiltration with ozone treatment
文章编号: N19042901
期刊: Science of The Total Environment
作者: Weiwei Huang, Weiguang Lv, Wenzong Zhou, Mengliu Hu, Bingzhi Dong
更新时间: 2019-04-29
摘要: This study investigated the fouling behavior and mechanism of ozone treatment correlating to water characteristics for micro-polluted water during ultrafiltration (UF). The results indicated that pre-ozonation efficiently mitigated membrane fouling of natural organic matter (NOM). The higher ozone doses were, the more the performance transmembrane pressures (TMPs) decreased. Ozone mainly converted macro molecule organics into low molecule organics. Macro molecular biopolymers (BP) can be removed up to 35.5% with an ozone treatment of 9 mg/L, while low molecular weight building blocks of acids and humics (BB) and neutrals (LMWN) increased 7.25% and 14.62%, respectively, with an ozone treatment of 9 mg/L. Analysis of fluorescence excitation emission matrices (EEMs) coupled with parallel factor analysis (PARAFAC) indicated that ozone mainly removed soluble microbial organics and fulvic-like and humic-like organics but not tyrosine organics. Hydrophobic organics (HPO) were reduced with an increase of ozone doses, especially macro molecular BP and humic substances (HS), and the neutral hydrophilic fraction (N-HPI) was enhanced. Ozone treatment helped to reduce the interception of BP and HS in HPO and improved the interception of BP and HS in N-HPI, as well as BB and LMWN, in both fractions. Principal component analysis suggested that BP, as well as UV₂₅₄, had high correlations with a membrane fouling index, which can be used as the fouling indicator during ozone treatment.
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22805. 题目: Novel hybrid material humic acid impregnated magnetic chitosan nano particles for decontamination of uranium from aquatic environment
文章编号: N19042807
期刊: Journal of Environmental Chemical Engineering
作者: Hirakendu Basu, Sudeshna Saha, Mehzabin Vivek Pimple, Rakesh Kumar
更新时间: 2019-04-28
摘要: In this study, a novel nano-composite was developed by synthesizing humic acid modified magnetic chitosan nano particles for efficient removal of uranium. Due to the combined effects of magnetic chitosan nano particles and humic acid, the composite material showed excellent removal efficiency (>95%) for uranium at pH 5-7 within 10 minutes (equilibrium time). Sorption followed Langmuir isotherm and pseudo second order kinetic model. The sorption capacity was calculated to be 47.9 mg g-1. Zeta potential of the nano-composite and different species of uranium present are reported which helps to understand the mechanism of uptake. Graphical

22806. 题目: Iron oxides selectively stabilize plant‐derived polysaccharides and aliphatic compounds in agricultural soils
文章编号: N19042806
期刊: European Journal of Soil Science
作者: D. Wan, T. H. Ye, Y. Lu, W. L. Chen, P. Cai, Q. Y. Huang
更新时间: 2019-04-28
摘要: A strong link exists between iron oxides and soil organic carbon (SOC). However, the role of iron oxides in the preservation of SOC in agricultural soil remains poorly understood. In this study, we comprehensively examined the concentration, molecular composition and biological sources of iron oxide‐bound organic carbon (Fe‐bound OC) in arable soils collected from 12 sites in central and east China. The results indicated that 6.2 ~ 31.2% of the SOC was bound to iron oxides in agricultural soil and that the binding mechanisms varied from adsorption in most soils to coprecipitation in those with a large content of organic carbon. The distribution of Fe‐bound OC showed no clear variation in relation to site, but Fe‐bound OC reached a peak in soils with an annual mean temperature of 16.4°C. Correlation analysis demonstrated that TOC might be the main determinant for the amount of Fe‐bound OC and that the binding mechanism is influenced by both TOC and the active Fe ratio. Comprehensive studies of C/N, ¹³C isotope and synchrotron radiation‐based Fourier transform infrared (SR‐FTIR) spectroscopy showed that iron oxides selectively protected plant‐derived aliphatic compounds and polysaccharides in agricultural soil. This study revealed the quantitative characterization, biological sources and molecular composition of Fe‐bound OC in arable soils, which provides useful information for evaluating and managing the global C cycle under the framework of climate change.

22807. 题目: Soil organic carbon accumulation and several physicochemical soil properties under stone pine and maritime pine plantations in coastal dune, Durusu-Istanbul
文章编号: N19042805
期刊: Environmental Monitoring and Assessment
作者: Musalam Mohammed Abdalmoula, Ender Makineci, Alper Gün Özturna, Servet Pehlivan, Abbas Şahin, Doğanay Tolunay
更新时间: 2019-04-28
摘要: The study was conducted in dune restoration sites introduced with maritime pine (MP, Pinus pinaster Aiton) and stone pine (SP, Pinus pinea L.) at different development stages (diameters at breast height (DBH) in which small-diameter forests (SDF) = 0–8 cm, medium-diameter forests (MDF) = 8–20 cm, large-diameter forests (LDF) = 20–36 cm, and upper large-diameter forests (UDF) = > 36 cm). There were 15 replicated plots in each stage of both species and 25 dune sites; thus, a total of 145 sample plots were selected. Soil samples were taken from six different depth layers (0–5, 5–15, 15–30, 30–50, 50–70, and 70–100 cm). Forest floors were sampled with five replicates in each plot, and they were separated into leaf + fermentation and humus layers to determine unit mass and carbon concentration. Forest floor mass is significantly increased (17–34 t/ha in MP and 28–57 t/ha in SP) with the development stage. Low organic carbon (0.09–0.36% in MP and 0.13–0.84% in SP) was found in the top soil layer despite a significant accumulation of forest floor. The soil organic carbon density varies between 3 and 34 t C/ha. As the stand development stage increases, clay concentrations in every depth layer increased and soil pH and calcium carbonate values tend to decrease. Results indicated that both species have capability to grow on sandy material within poor nutrient and water capacities in a 50-year restoration process. However, the accumulation of forest floor increased and organic matter storage in the topsoil (0–5 cm) remained quite low due to the slow decomposition process.

22808. 题目: Operational pattern affects nitritation, microbial community and quorum sensing in nitrifying wastewater treatment systems
文章编号: N19042804
期刊: Science of The Total Environment
作者: Zhaolu Feng, Yuepeng Sun, Tianle Li, Fanhua Meng, Guangxue Wu
更新时间: 2019-04-28
摘要: Achievement of nitrite accumulation is critical for the application of advanced nitrogen removal processes. Two lab-scale sequencing batch biofilm reactors (SBBRs) and two sequencing batch reactors (SBRs) were operated under intermittent aeration with different feeding patterns. The nitrite accumulation ratio was 56.6% (pulse feeding) and 68.9% (constant feeding) in SBBRs with nitritation. Nitrate accounted for 98% of the effluent nitrogen in SBRs with complete nitrification. The dominant nitrifier was Nitrosomonas in SBBRs and Nitrospira in SBRs. Four types of acyl homoserine lactones (AHLs) were detected. N‑[(RS)‑3‑Hydroxybutyryl]‑l‑homoserine lactone and N‑octanoyl‑l‑homoserine lactone had a high concentration in the extracellular polymeric substance phase, and had an obvious relationship with nitrite accumulation and ammonia removal. Various microbial communities coexisted in nitrifying systems, with diverse microbial interactions. Microorganisms harboring AHLs-related genes had more interactions with each other, suggesting that nitritation could be regulated by AHLs based quorum sensing.
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22809. 题目: Identification of the co-existence of low total organic carbon contents and low pH values in agricultural soil in north-central Europe using hot spot analysis based on GEMAS project data
文章编号: N19042803
期刊: Science of The Total Environment
作者: Haofan Xu, Alecos Demetriades, Clemens Reimann, Juan J. Jiménez, Juliane Filser, Chaosheng Zhang, GEMAS Project Team
更新时间: 2019-04-28
摘要: Total organic carbon (TOC) contents in agricultural soil are presently receiving increased attention, not only because of their relationship to soil fertility, but also due to the sequestration of organic carbon in soil to reduce carbon dioxide emissions. In this research, the spatial patterns of TOC and its relationship with pH at the European scale were studied using hot spot analysis based on the agricultural soil results of the Geochemical Mapping of Agricultural Soil (GEMAS) project. The hot and cold spot maps revealed the overall spatial patterns showing a negative correlation between TOC content and pH values in European agricultural soil. High TOC contents accompanying low pH values in the north-eastern part of Europe (e.g., Fennoscandia), and low TOC with high pH values in the southern part (e.g., Spain, Italy, Balkan countries). A special feature of co-existence of comparatively low TOC contents and low pH values in north-central Europe was also identified on hot and cold spot analysis maps. It has been found that these patterns are strongly related to the high concentration of SiO₂ (quartz) in the coarse-textured glacial sediments in north-central Europe. The hot spot analysis was effective, therefore, in highlighting the spatial patterns of TOC in European agricultural soil and helpful to identify hidden patterns.
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22810. 题目: Experimental and quantum-chemical study of differential absorbance spectra of environmentally relevant species: A study of quercetin deprotonation and its interactions with copper (II) ions
文章编号: N19042802
期刊: Science of The Total Environment
作者: Chenyang Zhang, Gregory V. Korshin, Andrey M. Kuznetsov, Mingquan Yan
更新时间: 2019-04-28
摘要: This study compared the experimental and theoretically calculated differential absorbance spectra (DAS) of quercetin, which is a typical model compound of natural organic matter (NOM) that is found in biochemical and environmental systems. Absorbance spectra of quercetin, which has five exchangeable protons, were generated at each state of deprotonation and its binding with Cu(II) ions. The spectra showed that the emergence of characteristic peaks in the experimental DAS was associated with the deprotonation of quercetin and its binding with Cu(II). Calculations of the theoretical DAS were conducted based on the time-dependent density functional theory (TD-DFT) methods and yielded results that were consistent with the experimental DAS data because the features in the absorbance spectra were primarily associated with the electron transitions from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) in the molecule. The appearance of the characteristic peaks in the DAS reflects the changes of the structure and electron distribution of the organic molecules that are induced by water treatment or environmental processes.
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22811. 题目: Quantifying the relationships between soil fraction mass, fraction carbon, and total soil carbon to assess mechanisms of physical protection
文章编号: N19042801
期刊: Soil Biology and Biochemistry
作者: Alison E. King, Katelyn A. Congreves, Bill Deen, Kari E. Dunfield, R. Paul Voroney, Claudia Wagner-Riddle
更新时间: 2019-04-28
摘要: Relationships between soil fractions (their mass or carbon (C)) and soil organic carbon (SOC) have been used to develop central ideas in SOC research. However, few attempts have been made to quantify the relationship between SOC and all soil fractions, despite the potential of such an effort to address SOC stabilization processes. We identified 41 published studies that used diverse management techniques to cause a change in SOC concentration and disrupted soil into macroaggregates (>250 μm), free microaggregates (53–250 μm) and free silt + clay (<53 μm), subsequently disrupting macroaggregates into constituent fractions (coarse particulate organic matter [cPOM] > 250 μm, occluded microaggregates, and occluded silt + clay). We used linear hierarchical models to quantify relationships between mass, C concentration and total C of fractions and SOC. Soil mass redistribution toward macroaggregates was associated with SOC accumulation, however total microaggregate mass (free + occluded) did not increase with macroaggregate mass, as would be expected given de novo microaggregate formation within macroaggregates. Instead, high SOC soils exhibited a greater percent of total microaggregates occluded in macroaggregates. Occlusion in macroaggregates was also associated with increased C concentrations of microaggregates (35% higher, SE = 3.2) and silt + clay (30% higher, SE = 3.9) relative to their free counterparts. Taken together, these relationships suggest reduced macroaggregate turnover promotes SOC accumulation via the stabilization of C into occluded fractions. Rates of SOC increase with silt + clay C concentrations failed to increase with mean site-level SOC concentration, indicating of the studied soils (median SOC concentration = 14 g kg⁻¹; max 68), SOC accumulation appears unlikely to be limited by C storage capacity in the silt + clay fraction. For each unit SOC gain, macroaggregates accounted for 83% (95% CI = 74, 91), and occluded microaggregates for 43% (95% CI = 33, 52), consistent relationships that have potential to be used as benchmarks for fraction-based SOC models.
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22812. 题目: Antimonite Complexation with Thiol and Carboxyl/Phenol Groups of Peat Organic Matter
文章编号: N19042709
期刊: Environmental Science & Technology
作者: Johannes Besold, Naresh Kumar, Andreas C Scheinost, Juan Lezama Pacheco, Scott Fendorf, Britta Planer-Friedrich
更新时间: 2019-04-27
摘要: Peatlands and other wetlands with abundant natural organic matter (NOM) are important sinks for antimony (Sb). While formation of Sb(III) sulfide phases or Sb(III) binding to NOM are discussed to decrease Sb mobility, the exact binding mechanisms remain elusive. Here, we reacted increasing sulfide concentrations with purified model peat at pH 6, forming reduced organic sulfur species, and subsequently equilibrated the reaction products with 50 μM of antimonite under anoxic conditions. Sulfur solid-phase speciation and the local binding environment of Sb were analyzed using X-ray absorption spectroscopy. We found that 85% of antimonite was sorbed by untreated peat. Sulfide-reacted peat increased sorption to 98%. Shell-by-shell fitting of Sb K-edge X-ray absorption fine structure spectra revealed Sb in untreated peat bound to carboxyl or phenol groups with average Sb–carbon distances of ∼2.90 Å. With increasing content of reduced organic sulfur, Sb was progressively coordinated to S atoms at distances of ∼2.45 Å and Sb–carbon distances of ∼3.33 Å, suggesting increasing Sb–thiol binding. Iterative target factor analysis allowed exclusion of reduced inorganic Sb–sulfur phases with similar Sb–sulfur distances. In conclusion, even when free sulfide concentrations are too low for formation of Sb–sulfur precipitates, peat NOM can sequester Sb in anoxic, sulfur-enriched environments.

22813. 题目: Removal and Oxidation of Arsenic from Aqueous Solution by Biochar Impregnated with Fe-Mn Oxides
文章编号: N19042708
期刊: Water, Air, & Soil Pollution
作者: Lina Lin, Zhengguo Song, Yongchun Huang, Zulqarnain Haider Khan, Weiwen Qiu
更新时间: 2019-04-27
摘要: We explored the preparation of Fe-Mn oxide-biochar composites and applied them for the removal of arsenic (As) from aqueous solutions. All composites exhibited high As removal efficiencies that increased with increasing pH within the investigated range (pH 3–7). According to the equation fitting for adsorption processes, F₃M₁BC₁₈ (biochar:FeSO₄:KMnO₄, the weight ratios of 18:3:1) had the greatest sorption ability (Q_m = 8.80 mg g⁻¹), and the sorption process of F₃M₁BC₁₈ was well fitted with Freundlich isotherm. In addition, FTIR and XPS analyses indicated that Fe oxides and Mn oxide particles on the outer sphere resulted in more oxidation of As(III) to As(V). The best-performing composite was characterized before and after adsorption using a range of instrumental techniques, which better identify the properties of F₃M₁BC₁₈. Moreover, the physical properties, composition, and structures of the synthesized composites were investigated, and the As removal mechanism involving surface adsorption/oxidation was proposed with the high performance of Fe-Mn oxide-impregnated biochars, suggesting that these materials are well-suited for efficient water decontamination.

22814. 题目: Litter quantity, litter chemistry, and soil texture control changes in soil organic carbon fractions under bioenergy cropping systems of the North Central U.S.
文章编号: N19042707
期刊: Biogeochemistry
作者: Adam C. von Haden, Christopher J. Kucharik, Randall D. Jackson, Erika Marín-Spiotta
更新时间: 2019-04-27
摘要: Soil organic carbon (SOC) storage is a critical component of the overall sustainability of bioenergy cropping systems. Predicting the influence of cropping systems on SOC under diverse scenarios requires a mechanistic understanding of the underlying processes driving SOC accumulation and loss. We used a density fractionation technique to isolate three SOC fractions that are conceptualized to vary in SOC protection from decomposition. The free light fraction (FLF) is particulate SOC that is present in the inter-aggregate soil matrix, the occluded light fraction (OLF) is contained within aggregates, and the heavy fraction (HF) is associated with minerals. We evaluated surface (0 to 10 cm depth) SOC fraction changes from baseline conditions 5 years after biofuel cropping system establishment at two temperate sites with contrasting soil textures. The biofuel cropping systems included no-till maize, switchgrass, prairie, and hybrid poplar. The FLF concentration (g fraction C g bulk soil⁻¹) did not change significantly from baseline levels under any of the cropping systems at either site after 5 years. Except for poplar, OLF concentrations were reduced in all systems at the site with coarse-textured soils and maintained at the site with fine-textured soils. In poplar systems, OLF concentrations were maintained on coarse-textured soils and increased on fine-textured soils. The HF concentrations also increased under poplar on the coarse-textured soil. A structural equation model indicated that OLF concentrations increased with lower litter C:N, and HF concentrations increased with greater litter quantity and lower litter C:N mass ratios. C:N increased over time within all SOC fractions, suggesting that all pools are sensitive to land-use change on sub-decadal timescales. In agreement with modern SOC theory, our empirical results indicate that increasing litter input quantity and promoting plant species with low C:N litter may improve SOC storage in aggregate and mineral-associated soil fractions.

22815. 题目: Podzolisation preserves ichnofossils constructed by ghost shrimp
文章编号: N19042706
期刊: CATENA
作者: Pedro Martinez, Peter Buurman, Josiane Millani Lopes-Mazzetto, Diego Luciano do Nascimento, Pablo Vidal-Torrado
更新时间: 2019-04-27
摘要: Ichnofossils of ghost shrimps (e.g., Ophiomorpha nodosa and Callichirus major) are interpreted worldwide as records of sea level fluctuations and provide reliable evidence of sedimentation rate, salinity, and substrate type. The preservation of these ichnofossils was previously ascribed to the polysaccharide mucus produced by ghost shrimps when burrows were built. We found evidence that these ichnofossils were preserved due to the impregnation of the burrow walls by dissolved organic matter (DOM) during podzolisation that took place after the galleries had been abandoned. Our study was conducted on a tropical barrier island in southeastern Brazil with a spatial gradient of podzolisation intensity. We made a detailed macromorphological description of the ichnofossils at the soil profile scale. Then, we used thin sections of undisturbed soils to identify sand grain arrangements and organic matter (OM) accumulation. We detected three macromorphological structures, (i) tubular gallery wall, (ii) sandy infilling of the gallery, and (iii) soil matrix outside the gallery. In the micromorphology analysis, we identified that the tubular wall is impregnated with monomorphic OM also found outside the burrow but in lower concentration. Sand grains in the wall of the gallery are tightly packed, causing a lower porosity than inside and outside the trace fossil. The precipitation of monomorphic OM is due to stagnation of DOM that percolated through the soil. Water with DOM is trapped in the wall of the tubule because of its smaller pores. The ghost shrimps constructed their burrows in marine sediments without podzolisation. Then, with the progradation of the shoreline, the sediments were colonized by restinga forest adding DOM to the soil and podzolisation started. The extent to which DOM is produced depends on vegetation development, therefore, the accumulation of DOM in the B horizon that enables the preservation of the ichnofossils is constrained by vegetation development and progradation of the shoreline.

22816. 题目: The magnetic biochar derived from banana peels as a persulfate activator for organic contaminants degradation
文章编号: N19042705
期刊: Chemical Engineering Journal
作者: Xing Rong, Meng Xie, Lingshuai Kong, Vinothkumar Natarajan, Long Ma, Jinhua Zhan
更新时间: 2019-04-27
摘要: The magnetic biochar (γ-Fe₂O₃@BC) derived from banana peels was synthesized by a facile one-pot thermal process and used as the cost-effective and recyclable persulfate (PS) activator for organic contaminants degradation. The results showed that the encapsulated iron oxide nanoparticles not only introduced the magnetism into biochar for easy separation, but also influenced the catalytic ability for PS activation. The γ-Fe₂O₃@BC was found to be highly effective for bisphenol A (BPA) degradation without pH adjustment. A complete removal of BPA was obtained within 20 min with an observed rate constant (k_obs) of 0.1849 min⁻¹, which was almost two times as large as that (0.0956 min⁻¹) of pure biochar. Further, it exhibited high mineralization efficiency for the degradation of various organic contaminants. The high catalytic activity could be attributed to large BET surface area, dispersed iron species, abundant oxygen functional groups and rich doped nitrogen. Radical quenching experiments and electron spin resonance (ESR) studies confirmed that OH, SO₄⁻ and O₂⁻ were all involved in the radical oxidation process which was responsible for BPA degradation. A mechanism of PS activation by the γ-Fe₂O₃@BC catalyst was proposed based on the synergistic effect of biochar and iron.
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22817. 题目: Estimation of plot-level soil carbon stocks in China's forests using intensive soil sampling
文章编号: N19042704
期刊: Geoderma
作者: Shangshi Liu, Haihua Shen, Xia Zhao, Luhong Zhou, He Li, Longchao Xu, Aijun Xing, Jingyun Fang
更新时间: 2019-04-27
摘要: Forest soil is a large carbon (C) pool and plays a pivotal role in the global C cycle. The accurate estimation of soil organic carbon (SOC) stocks in forests is the cornerstone of studying the C budget; however, current assessments of forest SOC stocks are highly uncertain. One of the key reasons for this uncertainty is that most previous studies only used a few soil profiles for their estimation, whereas SOC stocks are highly spatially heterogeneous. To accurately evaluate the plot-level SOC stocks of China's forests, we conducted intensive soil sampling (100 soil cores within a plot) in 33 plots across 11 forest sites from south to north China. The average SOC density (SOCD) of these forest sites was 137.4 ± 12.1 Mg C ha⁻¹ (0–100 cm), with significant geographic variations. The highest SOCD (306.8 ± 7.6 Mg C ha⁻¹) was observed in deciduous needleleaf forest (boreal forest) in northeast China, while the lowest one (64.8 ± 0.9 Mg C ha⁻¹) was found in subtropical evergreen broadleaf forest in south China. We also showed that the error of the SOCD estimates obtained from the intensive soil sampling was significantly smaller than that of estimates obtained from the traditional sampling method (5.3 ± 1.3% vs. 24.2 ± 5.6%, with a confidence level of 0.95). Our results suggest that intensive sampling can significantly reduce the uncertainty in forest SOC stock estimation by guarding against the effects of spatial heterogeneity, and provide an important methodological reference for accurately evaluating forest SOC stocks and C budgets in other regions.

22818. 题目: Multi-spectroscopic and elemental characterization of southern Australian asphaltites
文章编号: N19042703
期刊: Organic Geochemistry
作者: Alan G. Scarlett, Alex I. Holman, Svetoslav V. Georgiev, Holly J. Stein, Roger E. Summons, Kliti Grice
更新时间: 2019-04-27
摘要: Strandings of various types of bitumen along the coast of southern Australia are long known. Among these, brittle, angular lumps termed ‘asphaltites’ are possibly sourced from Cretaceous source rocks linked to an oceanic anoxic event (OAE), but the exact source remains unclear. The unusual chemical composition of these asphaltites and their survival during transport and shoreline stranding suggest that they formed by nearby submarine seepage of asphaltene-rich crude oils. Here, we provide a detailed organic and inorganic geochemical characterization of asphaltites to constrain their origin and age. High-pressure hydropyrolysis (HyPy) of asphaltene fractions from ten asphaltites released similar assemblages of macromolecularly bound compounds, suggesting a common source for all asphaltites. Comprehensive gas chromatography–time-of-flight mass spectrometry (GC×GC-TOFMS) was used to compare these asphaltene-derived compounds with the maltene fractions, while compound specific isotope analysis (CSIA) was used to compare δ¹³C and δ²H of n-alkanes and isoprenoids. A large offset between the δ²H of the n-alkanes and isoprenoids suggests oil generation and expulsion at low thermal maturity. The mean concentrations of isorenieratane and chlorobactane, carotenoid derivatives indicative of photic zone euxinia (PZE), in the asphaltites were 8.8 ± 0.8 SEM µg g^-1 and 1.4 ± 0.1 SEM µg g^-1, respectively. A mean Aryl Isoprenoid Ratio of 0.75 (SD = 0.17) is accompanied by Pr/Ph of ∼1.2. These features strongly support persistent PZE conditions at the level expected for an OAE. Trace metal contents of the asphaltites, including low selenium and high vanadium concentrations, also support anoxic conditions. Rhenium-osmium (Re-Os) analyses constrain the age of asphaltite generation to 103 ± 22 Ma, with a relatively low initial ¹⁸⁷Os/¹⁸⁸Os ratio of 0.44 ± 0.18. Integrating local geologic knowledge with organic and inorganic geochemistry and Re-Os isotopic results, we identify a Cretaceous unit associated with OAE1a (∼125 Ma) as the most likely source of the asphaltites. Alternative scenarios involving source rocks deposited during OAE1b (∼112 Ma) are possible, but require rapid burial of organic-rich sediments to reach required maturation levels in a shorter time.
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22819. 题目: Sources and burial fluxes of sedimentary organic carbon in the northern Bering Sea and the northern Chukchi Sea in response to global warming
文章编号: N19042702
期刊: Science of The Total Environment
作者: Kui Wang, Haisheng Zhang, Xibin Han, Wenxian Qiu
更新时间: 2019-04-27
摘要: The Arctic and subarctic seas are the major CO₂ sink areas on earth. In this study, the vertical variation characteristics of organic carbon, total nitrogen and their ratio (C_org/N_t), stable isotopes δ¹³C and δ¹⁵N, and BIT (branched and isoprenoid tetraether) index of GDGTs (glycerol dialkyl glycerol tetraethers) in combination with ²¹⁰Pb-dating were used to analyze the changes in the marine and terrestrial sources of organic carbon in the northern Bering Sea (site 1), western Beaufort Sea slope (site 2) and northern Chukchi Sea (site 3). Organic carbon burial fluxes (OCBF) in the context of global warming were also explored at sites 1 and 3. The results showed that organic matter in these sediments were a mixed input of marine and terrestrial sources, and the BIT index and δ¹³C of site 2 suggested that the terrestrial soil organic matter was dominant. Based on a combination of ²¹⁰Pb dating and C_org, the sedimentary OCBF at site 1 was 2.29–3.65 mg cm⁻² y⁻¹, and at site 3 was 0.00–0.41 mg cm⁻² y⁻¹. The temperature anomalies and sea ice changes in the Arctic in the past 100 years were compared with the burial fluxes of the terrestrial organic carbon. At site 1, the results indicated that fast melting of seasonal sea ice led to earlier arrival of ice algae bloom, enhanced zooplankton feeding and reduced carbon burial from 1947 to 2010, and the sudden increase in carbon burial after 2010 was attributed to an increase in primary productivity and terrestrial organic matter input due to an accelerated melting of sea ice. There was a smaller change in marine organic carbon content in site 3, but OCBF increased after a pre-1965 decrease, mainly controlled by terrestrial organic matter input associated with temperature rising and sea ice melting during recent decades.
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22820. 题目: Catalytic pyrolysis coupling to enhanced dewatering of waste activated sludge using KMnO₄Fe(II) conditioning for preparing multi-functional material to treat groundwater containing combined pollutants
文章编号: N19042701
期刊: Water Research
作者: Jing Ai, Weijun Zhang, Feifei Chen, Guiying Liao, Dandan Li, Xia Hua, Dongsheng Wang, Ma Teng
更新时间: 2019-04-27
摘要: Sewage sludge, the major by-product during the primary treatment and subsequent biotreatment of wastewater, is increasingly generated around the world. KMnO₄Fe(II) consists both oxidation properties of KMnO₄ and flocculation ability by in-situ formed Fe(III) and is widely used in water treatment. In this study, KMnO₄Fe(II) was used as chemical conditioners to synchronously improve sludge dewatering performance and catalyze the biomass pyrolysis of waste activated sludge for preparing multi-functional material to remedy arsenic containing groundwater. The results showed that the sludge dewaterability was significantly improved due to the moderate pre-oxidation of extracellular polymeric substances by KMnO₄, and then the sludge particles were re-flocculated by Fe(III) generated from KMnO₄Fe(II). The conditioned sludge cake was then utilized for preparing sludge-based carbon (Fe-Mn-SBC) which was systematically characterized. The surface area of Fe-Mn-SBC was characteristic of high surface area (100.08 m²/g) which had a great adsorption capacity on arsenic. Besides, Fe-Mn-SBC could effectively oxidize As(III) to As(V), and addition of low dose of H₂O₂ can further improve total arsenic removal due to catalytic peroxidation of Fe-Mn-SBC. Besides, it was found that the presence of humic acid could inhibit the hydroxy iron formation and compete for the active adsorption sites and then resulted in the decrease in arsenic removal, and the co-existing humic acid could also be removed by adsorption of Fe-Mn-SBC. This work proposed a novel sludge treatment process by combining enhanced sludge dewatering with catalytic pyrolysis for preparing multi-functional materials, and they are promising in treatment of water containing combined pollutants.
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