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25261. 题目: Engineered biochar composite fabricated from red mud and lipid waste and synthesis of biodiesel using the composite
文章编号: N18120603
期刊: Journal of Hazardous Materials
作者: Kwangsuk Yoon, Jong-Min Jung, Dong-Wan Cho, Daniel C.W. Tsang, Eilhann E. Kwon, Hocheol Song
更新时间: 2018-12-06
摘要: Co-pyrolysis of lipid waste and red mud was investigated to achieve valorization of red mud by fabricating biochar composite. For the further sustainable approach, this study intentionally employed carbon dioxide (CO₂) as reaction medium in the co-pyrolysis process. The use of CO₂ on co-pyrolysis of lipid waste and red mud enabled manipulation of the carbon distributions between pyrogenic products. CO₂ expedited the thermal cracking of lipid waste and further reacted with lipid waste during the thermolysis. These mechanistic roles of CO₂ were catalytically enhanced by the presence of mineral phases (Fe₂O₃) in red mud, thereby resulting in the enhanced formation of CO (40 times more at 550 °C). However, CO₂ suppressed dehydrogenation of lipid waste (∼ 50%), which resulted in the different pathway for reducing iron oxide in red mud. Moreover, as an aspect of valorization of red mud, catalytic capability of biochar composite was evaluated. As a case study, biodiesel (FAMEs) were synthesized, and all experimental findings suggested that biochar composite could be an effective catalyst for biodiesel synthesis. As compare to biodiesel synthesis using silica (92% yield at 360 °C), the equivalent biodiesel yield was achieved with the biochar at much lower temperature (130 °C).
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25262. 题目: Using adsorbent mixtures to mitigate membrane fouling and remove NOM with microgranular adsorptive filtration
文章编号: N18120602
期刊: Journal of Membrane Science
作者: Siamak Modarresi, Mark M. Benjamin
更新时间: 2018-12-06
摘要: This study investigated the removal of natural organic matter (NOM) from water, and its effect on membrane fouling, by mixtures of heated aluminum oxide particles (HAOPs) and powdered activated carbon (PAC) in both batch and microgranular adsorptive filtration (µGAF) reactors. In batch reactors, increasing the portion of HAOPs in the adsorbent mixture led to a steady increase in membrane fouling. However, this trend was reversed when the water was pretreated with the same adsorbent mixtures in µGAF reactors. The opposing trends tracked the trend for removal of the biopolymer fraction of the NOM.The results are consistent with a hypothesis that the fouling was caused primarily by formation of a condensed, biopolymer-rich gel layer on the membrane surface. According to this hypothesis, when the feed was pretreated in batch reactors, some foulants were collected on each adsorbent, with PAC collecting more foulant than HAOPs did, but the accumulated material did not condense into a gel. However, when μGAF reactors were used instead of batch reactors for pretreatment, the tight packing of the adsorbent particles promoted the formation of a gel, leading to increased NOM removal in general and increased foulant removal in particular. The fact that fouling mitigation increased with increasing amounts of HAOPs and decreasing amounts of PAC in the μGAF adsorbent layer suggests that HAOPs are much more effective than PAC at promoting formation of the gel layer. Generalizing this result, it appears that pretreatment by mixtures of adsorbents in μGAF reactors could have significant advantages over conventional approaches in which a single adsorbent is applied in a well-mixed reactor.
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25263. 题目: Insights into aggregation and transport of graphene oxide in aqueous and saturated porous media: Complex effects of cations with different molecular weight fractionated natural organic matter
文章编号: N18120601
期刊: Science of The Total Environment
作者: Mohai Shen, Xiao Hai, Yaxin Shang, Chuanrong Zheng, Peiwen Li, Yao Li, Wanwan Jin, Danlin Li, Yajuan Li, Jingyi Zhao, Hengtao Lei, Hui Xiao, Yunbei Li, Guangxuan Yan, Zhiguo Cao, Qingwei Bu
更新时间: 2018-12-06
摘要: The stability of nanomaterials in aquatic environment is a critical factor that governs their fate and ecotoxicity. Meanwhile, the interaction between nanomaterials and ubiquitous natural organic matter (NOM) is a vital process that influences the transport and biological effects of nanomaterials in the environment. However, impacts of NOM on the aggregation and transport of two-dimensional nanomaterials, especially for the increasingly used graphene oxide (GO), are not well understood. Particularly, there is lack of exploration on potential impacts of the heterogeneous properties of NOM on GO behaviour, especially that induced by the wide molecular weight (MW) span of NOM. In this study, effects of several kinds of well-characterized MW fractionated Suwannee River NOM (M_f-SRNOMs) on the aggregation and transport of GO in aqueous media and saturated porous media were investigated. Our results suggest that the stability and migration capacity of GO under most investigated electrolyte conditions are promoted by all Mf-SRNOMs, and efficiencies of different Mf-SRNOMs are generally positively correlated with their MW. Primarily, mechanisms including MW-dependent steric hindrance and sorption of Mf-SRNOMs onto GO are critical in stabilizing GO, and thus facilitating its transport. However, the stronger sorption of higher Mf-SRNOMs onto the GO basal plane through π-π interaction further facilitated the cation bridging between both ends of Mf-SRNOM and GO, and resulted in heteroaggregation of NOM-GO. Moreover, the weight analysis indicated that despite the fact that high Mf-SRNOMs only occupied a small percentage of pristine-SRNOM, they showed a stronger contribution towards pristine-SRNOM's capacity in stabilizing GO, when compared with that of lower MW counterpart. These findings pointed out that complex effects of the heterogeneities of NOM and cations should be highly relevant when the aggregation and transport behaviour of two-dimensional nanomaterials is investigated, and NOM fractions that are highly aromatic and of a higher MW should receive greater attention.
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25264. 题目: The Role of Reactive Iron in the Preservation of Terrestrial Organic Carbon in Estuarine Sediments
文章编号: N18120515
期刊: Journal of Geophysical Research: Biogeosciences
作者: B. Zhao, P. Yao, T. S. Bianchi, M. R. Shields, X. Q. Cui, X. W. Zhang, X. Y. Huang, C. Schröeder, J. Zhao, Z. G. Yu
更新时间: 2018-12-05
摘要: To better understand the role of reactive Fe (Fe_R) in the preservation of sedimentary OC (SOC) in estuarine sediments, we examined specific surface area (SSA), grain size composition, total OC (TOC), lignin phenols, Fe_R, Fe_R‐associated OC (Fe‐OC) and lignin phenols (Fe‐lignin), and δ¹³C of Fe_R‐associated OC (δ¹³C_Fe‐OC) in surface sediments of the Changjiang Estuary and adjacent shelf. An estimated 7.4 ± 3.5% of the OC was directly bound with Fe_R in the Changjiang Estuary and adjacent shelf. Unusually low TOC/SSA loadings and Fe‐OC/Fe ratios in mobile‐muds suggest that frequent physical reworking may reduce Fe_R binding with OC, with selective loss of marine OC. More depleted ¹³C_Fe‐OC relative to ¹³C of TOC (¹³C_bulk) in deltaic regions and mobile‐muds showed that Fe_R was largely associated with terrestrial OC, derived from extensive riverine OC and Fe inputs. A higher proportion of hematite in the mobile muds compared to the offshore samples indicated that Fe oxides are likely subjected to selective sorting and/or become mature during long‐term sediment transport. When considering the percentage of Fe‐OC to SOC and SOC burial rates in different marine environments (e.g., non‐deltaic shelf, anoxic basins, slope and deep sea), our findings suggest that about 15.6 ± 6.5% of SOC is directly bound to Fe_R on a global scale, which is lower than the previous estimation (~21.5%). This work further supports the notion of a “Rusty Sink” where, in this case Fe_R plays an important role in the preservation and potential transport of terrestrial OC in the marine environment.

25265. 题目: Glacial iron sources stimulate the Southern Ocean carbon cycle
文章编号: N18120514
期刊: Geophysical Research Letters
作者: C. Laufkötter, Alon A. Stern, Jasmin G. John, Charles A. Stock, John P. Dunne
更新时间: 2018-12-05
摘要: Icebergs and glacial meltwater have been observed to significantly affect chlorophyll concentrations, primary production and particle export locally, yet the quantitative influence of glacial iron on the carbon cycle of the Southern Ocean remains unknown. We analyse the impact of icebergs and glacial meltwater on the Southern Ocean carbon cycle in a global Earth System Model. We consider several simulations spanning low and high bounds of current estimates of glacial iron concentration. We find that a high glacial iron input produces the best agreement with observed iron and chlorophyll distributions. These high glacial iron input results indicate that about 30% of the Southern Ocean particle export production, i.e., the flux of particulate organic matter through the 100 m depth level, is driven by glacial iron sources. This export production is associated with an uptake of 0.14 Pg carbon per year, which reduces carbon outgassing in the Southern Ocean by 30%.

25266. 题目: Formation of mineral–mineral and organo–mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances
文章编号: N18120513
期刊: European Journal of Soil Science
作者: T. Guhra, T. Ritschel, K.U. Totsche
更新时间: 2018-12-05
摘要: Structures of colloidal compounds in soil including organo–mineral and mineral–mineral associations are considered as composite building units (CBUs) that may combine into soil microaggregates. Despite the ubiquitous occurrence of CBUs, the major formation mechanisms are rather obscure and little is known about whether they form primarily during weathering of the parent rocks or by aggregation processes from the soil suspension. We studied the formation of CBUs from suspensions composed of minerals and organic matter typical for temperate soils, i.e. quartz, goethite, illite and extracellular polymeric substances (EPS). Without EPS, we found CBUs formed as mineral–mineral associations by hetero coagulation of illite and quartz that is bridged by goethite. The presence of EPS, in contrast, led to the formation of a stable suspension of clay‐sized CBUs with no involvement of quartz. We explained this by the rapid formation of organo–mineral CBUs made of EPS‐associated goethite and EPS‐associated illite. The sorption of EPS to goethite screened its surface charge, thereby reducing the electrostatic attraction between goethite and illite. This interaction effectively impeded the formation of mineral–mineral CBUs. Moreover, interactions of EPS with goethite resulted in a marked decrease of the phosphorus/carbon ratio in the suspension. This suggested a preferred adsorption of phosphorus‐containing EPS constituents to goethite and in turn to a compositional fractionation of EPS constituents between the solid and liquid phase as shown by Fourier‐transform infrared spectroscopy with attenuated total reflection (FTIR–ATR). Laser light diffraction measurements revealed a shift from the fine silt fraction to that of the fine sand that also supports the role of EPS as a ‘binding’ agent.

25267. 题目: Soil organic carbon stocks in a tidal marsh landscape are dominated by human marsh embankment and subsequent marsh progradation
文章编号: N18120512
期刊: European Journal of Soil Science
作者: M. Van de Broek, L. Baert, S. Temmerman, G. Govers
更新时间: 2018-12-05
摘要: Tidal marshes are coastal and estuarine ecosystems that store large amounts of sedimentary organic carbon (OC). Despite the valuable ecosystem services they deliver, tidal marshes have been converted to other land‐use types over the past centuries. Although previous studies have reported large decreases in soil organic carbon (SOC) stocks after tidal marsh embankment, knowledge on the magnitude and rate of OC losses is still limited. Here, we studied the effect of stepwise embankments of brackish and salt marshes and subsequent marsh progradation on SOC stocks in the Scheldt estuary (the Netherlands). We collected samples from soil profiles along tidal marsh–reclaimed tidal marsh chronosequences and determined total OC stocks and the stable carbon signature of the OC. Our results showed that large losses of previously sequestered SOC occur on a decadal timescale with the embankment of brackish (−8.7 ± 0.7 kg OC m⁻²) and salt marshes (−6.7 ± 0.8 kg OC m⁻²). The (incomplete) replacement of tidal marsh OC by agricultural OC is substantially faster in topsoils (ca. a century) compared with subsoils (multiple centuries). Simulations with a coupled land use–SOC model showed that large rates of marsh progradation following embankment construction resulted in a substantial increase in landscape‐scale SOC storage, whereas large SOC losses occurred in landscapes dominated by embanked tidal marshes. The findings of our study might help to assess how these management practices affect regional SOC stocks.

25268. 题目: Synthesis and characterisation of a multifunctional oil-based drilling fluid additive
文章编号: N18120511
期刊: Environmental Earth Sciences
作者: Wu-Juan Sun, Guo-Qing Tian, Hang-Juan Huang, Guo-Min Lu, Cong-Yu Ke, Jun-Feng Hui, Xun-Li Zhang
更新时间: 2018-12-05
摘要: An oil-based drilling fluid additive H-DEA (or humic acid-cocamide diethanolamine) was synthesised using humic acid and cocamide diethanolamine as raw materials. The rheological behaviors of H-DEA showed that the synthesised product has the good properties in both decreasing the filtrate loss and improving rheology property of oil-based drilling fluids compared with other commercially available additives. Under the optimal additive amount of 3%, both API filtrate loss and yield point changed remarkably from 5.40 to 0.41 mL and 9.0 to 25.6 Pa, respectively. Furthermore, differential scanning calorimetry (DSC) showed that H-DEA has good thermal stability in a wide temperature range up to 170 °C. Infrared spectroscopy (IR) and rheological analysis revealed that the possible mechanism of the multifunctional effects may be attributed to the existing of high density of strong polar groups, hydrogen bonds, electrostatic forces, and intermolecular association on H-DEA molecular structure. The results of the study showed that the synthesised H-DEA can be potentially used as a multifunctional oil-based drilling fluid additive in oil-drilling excavation.

25269. 题目: Microalgae biochar-derived carbon dots and their application in heavy metal sensing in aqueous systems
文章编号: N18120510
期刊: Science of The Total Environment
作者: J. Plácido, S. Bustamante-López, K.E. Meissner, D.E. Kelly, S.L. Kelly
更新时间: 2018-12-05
摘要: This research seeks a coupled solution for managing the large amounts of biochar produced by microalgae biofuel production, and the necessity for novel, economic and accurate heavy metal sensing methods. Therefore, this study evaluated the transformation of microalgae biochar (MAB) into carbon dots (Cdots) and their subsequent application as heavy metal ion sensors in aqueous systems. The experimental phase included the transformation of MAB into microalgae biochar-derived carbon dots (MAB–Cdots), MAB–Cdot characterisation and the evaluation of the MAB–Cdots as transducers for the detection of four heavy metal ions (Pb²⁺, Cu²⁺, Cd²⁺, and Ni²⁺). MAB–Cdot fluorescence was stable over a wide range of pH and resistant to photo-bleaching, making them suitable as fluorescence probes. The MAB–Cdot fluorescence was quenched by all of the metal ions and displayed different quenching levels. Depending upon the ions involved, MAB–Cdots were used to detect the presence of heavy metal ions from concentrations of 0.012 μM up to 2 mM by measuring the reduction in fluorescence intensity. Neutral and slightly alkaline pHs were optimal for Cu²⁺ Ni²⁺ and Pb²⁺ heavy metal quenching. To quantify the concentration of the heavy metal ions, linear and logarithmic functions were used to model the MAB–Cdot fluorescence quenching. The sensing mechanism was determined to be reversible and purely collisional with some fluorophores less accessible than the others. This work demonstrated the ability to produce Cdots from microalgae biochar, examined their application as a transducer for detecting heavy metal ions in aqueous systems and paves the way for novel sensing systems using MAB-Cdots.
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25270. 题目: Molecular characteristics, proton dissociation properties, and metal binding properties of soil organic matter: A theoretical study
文章编号: N18120509
期刊: Science of The Total Environment
作者: Yuzhen Liang, Yang Ding, Pei Wang, Guining Lu, Zhi Dang, Zhenqing Shi
更新时间: 2018-12-05
摘要: Soil organic matter (SOM) is a key soil sorbent with a large number of reactive binding sites that may complex with metals, controlling their fate, transport, and bioavailability in soil. However, due to the complex and heterogeneous nature of SOM, it is not easy to probe its physical and chemical properties at the molecular level. In this study, an a priori method was developed to predict the molecular properties of SOM, which incorporated computational molecular modeling, SPARC Performs Automated Reasoning in Chemistry's (SPARC's) chemical reactivity models, and linear free energy relationships (LFERs). Specifically, the method uses SOM models simulated by molecular dynamics modeling based on the experimental elemental composition and functional group information of SOM. For the molecular characteristics, the molecular H/C and O/C ratios, molecular weight, aromatic index, and double bond equivalence of the SOM molecules were calculated. For the proton binding constants, the SPARC was used to calculate the microscopic pK_a values of every binding sites of individual molecules of the SOM model. Based on the pK_a values, the metal binding constants for individual monodentate binding sites were calculated using the Irving-Rossotti LFERs for different heavy metals. The results agreed reasonably with the default values used in the Windermere Humic Aqueous Model (WHAM) (VI) for the investigated metals. The theoretical SOM models, to some extent, represented the average properties of the investigated SOM. Overall, this study gives new quantitative and molecular insight into the structure and chemical properties of SOM. Detailed deprotonation and metal-SOM complexation information was gained for individual SOM binding sites. Such feasible and straightforward predictive scheme is useful to assess the risk of heavy metals in various aquatic and terrestrial environment involving heterogeneous natural organic matter.
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25271. 题目: Synergy of partial-denitrification and anammox in continuously fed upflow sludge bed reactor for simultaneous nitrate and ammonia removal at room temperature
文章编号: N18120508
期刊: Bioresource Technology
作者: Rui Du, Shenbin Cao, Baikun Li, Hanyu Zhang, Shuying Wang, Yongzhen Peng
更新时间: 2018-12-05
摘要: In this study, the synergy of high nitrite (NO₂^--N) accumulated partial-denitrification (PD) and anammox in a continuously fed upflow anaerobic sludge bed (UASB) reactor was verified for simultaneous nitrate (NO₃^--N) and ammonia (NH₄⁺-N) removal. A 225-days operation demonstrated that the relatively low total nitrogen (TN) concentration of 6.56 mg/L in effluent could be achieved with influent NH₄⁺-N and NO₃^--N both of 30 mg/L, resulting in a high TN removal of 89.1% at 17.5°C. Batch tests revealed that the NO₃^--N-to-NO₂^--N transformation ratio (NTR) of PD stabilized at 90% during the whole operation, which played a crucial role in the desirable performance. However, the PD and anammox activity was negatively impacted by the limited mass transfer with serious sludge flotation. Significantly, hydrodynamic mixing optimization by adjusting liquid recirculation ratio effectively enhanced the nitrogen removal. Moreover, protein composition and tightly-bound structure of EPS played an important role in the sludge stability.
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25272. 题目: Reduction of organic matter and disinfection byproducts formation potential by titanium, aluminum and ferric salts coagulation for micro-polluted source water treatment
文章编号: N18120507
期刊: Chemosphere
作者: Yang Wan, Xin Huang, Baoyou Shi, Jian Shi, Haotian Hao
更新时间: 2018-12-05
摘要: Typical Chinese source water has high content of low molecular weight and aromatic protein-like organic matter which is difficult to remove and poses a great challenge to conventional coagulation/flocculation. To investigate coagulation performance of this typical water, this research focused on organic matter removal characteristics and the associated disinfection byproducts formation potentials (DBPFPs) during the coagulation process by titanium salts compared with traditional aluminum and ferric salts. Results showed that based on the dissolved organic matter (DOM) removal, the optimal coagulant dosages of AlCl₃, FeCl₃ and TiCl₄ were 0.5 mM and the optimal initial pH values were 8, indicating that the DOM in the typical Chinese water could be effectively removed through sweeping and adsorption by metal hydroxides rather than the complexation and charge neutralization effect under acidic conditions. Compared these three coagulants, the highest ultra violet absorbance at 254 nm removal rate of 72.9% was achieved by TiCl₄. The three-dimensional excitation emission matrix results showed that the removal ability of humic acids by AlCl₃ was poorer than FeCl₃ and TiCl₄. The removal rate of low molecular weight components (1600 Da) by TiCl₄ was 20% higher than using AlCl₃ and 14% higher than FeCl₃. Comparing with AlCl₃ and FeCl₃, TiCl₄ had a better performance on the control of DBPFPs, especially for chloroform and dichloroacetic acid, due to its higher removal ability of aromatic organics. The trihalomethane formation potentials removal rate by TiCl₄ was three times higher than that by AlCl₃ and twice by FeCl₃, by which could be inferred that titanium salts achieved better removal of low molecular weight organic matter than aluminum and ferric salts.
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25273. 题目: Investigating spectroscopic and copper-binding characteristics of organic matter derived from sediments and suspended particles using EEM-PARAFAC combined with two-dimensional fluorescence/FTIR correlation analyses
文章编号: N18120506
期刊: Chemosphere
作者: Bin Hu, Peifang Wang, Chao Wang, Jin Qian, Tianli Bao, Yue Shi
更新时间: 2018-12-05
摘要: Different environmental dynamics of sediment organic matter (SOM) and suspended particulate organic matter (SPOM) result in great disparities in characteristics and subsequent interactions with heavy metals. In this study, sediments and suspended particles were collected from two large and shallow lakes (Taihu and Hongze Lake) to study the difference in the characteristics and copper binding properties between SOM and SPOM through spectroscopy method. Our results showed that SPOM in Taihu Lake was dominated by autochthonous tyrosine-like substance and SOM was dominated by terrestrial humic-like substance, whereas SPOM in Hongze Lake was dominated by terrestrial humic-like substances. Furthermore, dissolved organic matter (DOM) in Taihu and Hongze Lake was controlled by autochthonous protein and terrestrial humic substances, respectively. Comparison of SPOM between these two lakes indicated that various organic matter sources could be responsible for the organic matter characteristics in suspended particles. Meanwhile, relatively higher binding affinities and more binding sites were observed for SPOM in both two lakes compared to SOM through two-dimensional correlation spectroscopy (2D-COS) analysis of synchronous fluorescence spectra. Moreover, 2D-COS analysis of FTIR spectra revealed that hydrophobic groups (i.e., phenolic groups) had higher binding affinity than hydrophilic groups (i.e., polysaccharide groups) for both SOM and SPOM. Our results provide a new angle for understanding the suspended particles in shallow lakes, which might play a more important role in the environmental behaviors of heavy metals, than has been previously thought.
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25274. 题目: Organic-matter-rich shales of China
文章编号: N18120505
期刊: Earth-Science Reviews
作者: Caineng Zou, Rukai Zhu, Zhong-Qiang Chen, James G. Ogg, Songtao Wu, Dazhong Dong, Zhen Qin, Yuman Wang, Lan Wang, Senhu Lin, Jingwei Cui, Ling Su, Zhi Yang
更新时间: 2018-12-05
摘要: Organic-matter-rich shales are the main target rocks for unconventional oil and gas exploration and development across the world. In China, shale-gas geological resources are estimated as approximately 110 × 10¹² m³, with recoverable gas reserves of ca. 20 × 10¹² m³. Recoverable shale-oil reserves are estimated as ca. 5 × 10⁹ t. A total 35 important organic-matter-rich shale units have been recognized from Mesoproterozoic to Cenozoic strata across the entire China. These shales are categorized according to their origin under marine, marine–nonmarine transitional and lacustrine conditions. Shales of marine origin, with ca. 9 × 10¹² m³ recoverable resources, dominate China's potential in terms of total volume of organic-carbon. Currently, the most favorable marine shales for oil and gas exploration are found in the Sichuan Basin within the lower Cambrian Qiongzhusi Formation and in the Wufeng-Longmaxi formations of uppermost Ordovician through lower Silurian. A fortuitous combination of of sea-level variations, of paleo-productivity, of tectonic activity causing development and migration of partially closed deep basin depocenters, and of sediment accumulation rates controlled the extensive deposition and distribution of organic-matter-rich shales in these Wufeng and Longmaxi formations. Organic-matter-rich shales in marine-nonmarine transitional facies associated with coal measures occur in North China within the Carboniferous and Permian, and in South China within the Permian. These Carboniferous-Permian organic-matter-rich shales are important source rocks for the gas fields in the Ordos and Sichuan Basins. Abundant organic-rich shales are also widely distributed within coal-bearing clastics and coal-measure shales of fluvial, lacustrine, and swamp facies in Upper Triassic to Middle Jurassic successions of many basins. Lacustrine organic-rich shales were deposited during the Permian through Neogene in various freshwater to saline lake settings. Lacustrine organic-matter-rich shales are the main oil source rocks in the Songliao, Bohai Bay, Ordos and Junggar basins. Lacustrine algae contributed to the rain of organic matter; and the preservation of organic matter and distribution of organic-rich shale was controlled by lake currents, water depth and oxygen-poor conditions, with enhanced preservation when buried by turbidity currents. Algal blooms were partly induced by trace nutrients from volcanic ash falls in all of these lacustrine basins. Seawater intrusion into the freshwater lake of the Songliao Basin promoted some episodes of black shales. Saline lacustrine basins, such as middle Permian Junggar Basin, contain organic-rich dolomite mudstone that mainly formed during hot climate conditions when the lakes had high salinity and stratified water columns that deprived the bottom waters of oxygen, thereby preserving massive amounts of organic matter. Laminated calcite-rich mudstone in the saline lacustrine settings formed in more brackish waters under stable warm conditions and weak biological activity. The modeling of the factors controlling the distribution of organic-matter-rich shales within China's basins is important for the exploration and development of unconventional oil and gas resources.

25275. 题目: Humic substances from green waste compost: An effective washing agent for heavy metal (Cd, Ni) removal from contaminated sediments
文章编号: N18120504
期刊: Journal of Hazardous Materials
作者: Siyu Zhang, Jia Wen, Yi Hu, Ying Fang, Haibo Zhang, Lang Xing, Yongxu Wang, Guangming Zeng
更新时间: 2018-12-05
摘要: In this study, humic substances (HS) selected from 8 composting groups (peanut straw, sesame straw, corn straw and deciduous leaves, with or without grape marc) were used to remove Cd and Ni from artificially contaminated sediments. Sesame straw compost appeared to have the highest removal capacity for heavy metals through a series comparison on Cd removal efficiency, yield of HS and fulvic acids (FA), and seed germination index. The selected sesame HS was further used to wash two contaminated sediments of varying properties (a clay type for sediment 1 and a silty loam for sediment 2). Batch desorption experiments were conducted to determine the optimum HS concentration, equilibrium time, pH, solid-to-liquid ratio, and washing frequency. Under optimum conditions, a triple washing removed 74.16% of Cd and 42.91% of Ni from sediment 1, and 86.88% of Cd and 43.84% of Ni from sediment 2, respectively, whereas a commercial FA only achieved half of the efficiency. After washing, both sediments were identified with increased contents of total organic matter total nitrogen and phosphorus. Therefore, HS from the sesame straw compost is a cost-effective, efficient and environmental-friendly washing agent to remove heavy metals from contaminated sediments.

25276. 题目: Exploration of the formation of self-forming dynamic membrane in an upflow anaerobic sludge blanket reactor
文章编号: N18120503
期刊: Separation and Purification Technology
作者: Muhammad Ahmar Siddiqui, Ji Dai, Dao Guan, Guanghao Chen
更新时间: 2018-12-05
摘要: Self-forming dynamic membrane bioreactor (SFDMBR) technology has drawn increased attention recently, especially for its potential application in anaerobic conditions to retain slow growing sludge in the system. To attain maximum sludge retention, quick development of a self-forming dynamic membrane (SFDM) is deemed necessary. A lab-scale upflow anaerobic sludge blanket (UASB) reactor with a side-stream anaerobic SFDMBR was used in this study to investigate the factors affecting the successful formation of a SFDM and identify the indicators of success. The SFDM formed successfully within 60 to 90 min to produce permeates of less than 10 NTU after system optimization. The short formation period and low permeate turbidity provide strong support for the potential of retaining a large amount of sludge in the UASB reactor. The thickness and wet density of the SFDM increased continuously with the decrease in surface area during the formation period. Extracellular polymeric substances (EPS) played an essential role in SFDM formation. Humic acid was the dominant EPS in the sludge, but it did not significantly affect the SFDM formation. Even though polysaccharides only represented 3.7% of the total EPS in sludge, it accumulated on the supporting material as a percentage of the total EPS increased significantly from 6.2% after 60 min to 10.8% after 720 min. Therefore, polysaccharides were the primary reason for the formation of the SFDM. β-polysaccharides were more important because it mainly accumulated on the fiber of the supporting material.
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25277. 题目: Mineral identity, natural organic matter, and repeated contaminant exposures do not affect the carbon and nitrogen isotope fractionation of 2,4-dinitroanisole during abiotic reduction
文章编号: N18120502
期刊: Environmental Science: Processes Impacts
作者: Matthew J. Berens, Bridget A. Ulrich, Jennifer H. Strehlau, Thomas B. Hofstetter, William A. Arnold
更新时间: 2018-12-05
摘要: The recent development of insensitive munitions, such as 2,4-dinitroanisole (DNAN), as components of military explosives has generated concern for potential subsurface contamination and created a need to fully characterize their transformation processes. Compound specific isotope analysis (CSIA) has proven to be a useful means of assessing transformation pathways according to characteristic stable isotope fractionation patterns. The C and N isotope fractionation of DNAN associated with abiotic and enzymatic hydrolysis was recently assessed. The extent to which DNAN isotope fractionation will be affected by other potentially competing transformation pathways known for nitroaromatic compounds (e.g., reduction) and if previous knowledge can be extrapolated to other environmental matrices remains to be understood. Here, we investigated the C and N isotope fractionation and reaction rate constants of DNAN during abiotic reduction mediated by mineral-associated Fe(II) species as a function of mineral type, natural organic matter presence, and repeated exposures to DNAN. Though rate constants varied, N and C apparent kinetic isotope effects (AKIEs) remained consistent across all experiments (averaged values of ¹⁵N-AKIE = 1.0317 ± 0.0064 and ¹³C-AKIE = 1.0008 ± 0.0005) and revealed significant ¹⁵N- and minimal ¹³C-enrichment in agreement with previous work on nitroaromatic compounds. Moreover, the observed fractionation was clearly distinct from trends for abiotic and enzymatic hydrolysis. This study provides a strengthened basis for the use of CSIA as a robust tool for monitoring DNAN degradation in complex environmental matrices as a component of future remediation efforts.
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25278. 题目: Soil formation on calcium carbonate-rich parent material in the outer Carpathian Mountains – A case study
文章编号: N18120501
期刊: CATENA
作者: Joanna Beata Kowalska, Tomasz Zaleski, Agnieszka Józefowska, Ryszard Mazurek
更新时间: 2018-12-05
摘要: In this study, ten stratified calcium carbonate–rich soil profiles from the Polish Outer Carpathians were investigated in order to identity the influence of parent material variability and slope processes on soil diversity and their evolution. Moreover, we evaluated the morphological and physico-chemical soil properties to recognize the diagnostic horizons and classification of such soils. While it is usually thought that carbonate-rich soils are considered as formed in situ, these study soils clearly presented layering and contribution of materials, as they were developed from mixed substrates of different origin, e.g. as the result of mass movements and possible aeolian silt contribution. Irrespective of the type of parent material, every investigated soil showed traces of slope processes, resulting in heterogeneous soil profiles. Further, a few different patterns of primary calcium carbonate arrangement were found. In general, the studied soils were characterized by enrichment with calcium carbonate, not only due to inheritance from calcium carbonate–rich parent material but also translocation of calcium carbonate within soil profiles, the latter depending on soil stratification.Based on the obtained results, four pathways of soil evolution were formulated. Leptosols, which represent initial calcium carbonate–rich soils, may evolve in different directions. First, formation of the thick layer suitable for cambic horizon development under deciduous forests, which enables the classification of such soils as Cambisols, depends on slope processes and allochthonous material deposition. In turn, the decrease of mineralization rates for organic matter, delivery of soil material from the upper parts of the slope as well as mixing of organic matter by mesofauna result in the formation of mollic horizons and transformation of Leptosols into Phaeozems. Further erosion and redeposition of fine soil material provide two types of slope sediments: i) those with silt loam texture dominance, and ii) clay loams interstratified with silty substrates. The first type of sediments are more suitable for water percolation, and after carbonate leaching clay dispersion and translocation occur. In such materials, Luvisols may develop. Sediments with a prevalence of clay loam aided Stagnosol formation, in which pools of carbonates were stabilized due to the reduction of water percolation, leading to stagnation.
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25279. 题目: A conceptual framework to study soil aggregate dynamics
文章编号: N18120410
期刊: European Journal of Soil Science
作者: C. O. Márquez, V. J. García, R. C. Schultz, T. M. Isenhart
更新时间: 2018-12-04
摘要: The objective of this study was to develop a conceptual framework to study soil aggregate dynamics through the integration of aggregation, disruption, stabilization and destabilization processes of soil constituent units. We used aggregate‐size distribution and water stability of macroaggregates to evaluate changes in soil aggregates in two ecosystems where one is the ‘reference’ state and the other is the ‘new’ state. The framework was validated with data from a (i) non‐buffered annual row crop (ARC) system, (ii) no‐till (NT) system and (iii) bare fallow (BF) system. The dynamics of soil aggregates in the ARC were dominated by the disruption of aggregates (the aggregation–disruption index (ADI) was –0.08), in NT by the aggregation process (ADI = 0.03) and in BF by the disruption of aggregates (ADI = –0.20). Three pathways were observed: (i) expression of the aggregation process essential in reestablishing soil structure and functionality, (ii) expression of the disruption process critical in the destruction of soil structure and (iii) prevalence of mixed behaviour where the dominant process depended on the relative rate of aggregation and disruption. The proposed framework and study of the carbon associated with aggregates could pave the way to the development of a methodology for the quantitative study of soil organic carbon (SOC) dynamics, carbon inputs (outputs), soil carbon fractions, and edaphic and biotic conditions that regulate SOC dynamics.

25280. 题目: Nitrogen removal in response to the varying C/N ratios in subsurface flow constructed wetland microcosms with biochar addition
文章编号: N18120409
期刊: Environmental Science and Pollution Research
作者: Xu Zhou, Shubiao Wu, Ruigang Wang, Haiming Wu
更新时间: 2018-12-04
摘要: Biochar as a substrate has great potential to promote pollutant removal efficiency in subsurface flow constructed wetlands (SSFCWs). However, information about the effect of different influent C/N ratios on treatment efficiency in SSFCWs with biochar is still scarce. In this study, SSFCW microcosms added with and without biochar were performed to investigate comparatively nitrogen removal in response to the domestic wastewater with varying C/N ratios. The results demonstrated that nitrogen removal increased at influent C/N ratios from1 to 3, and then decreased with the rising influent C/N ratios from 3 to 15 in different SSFCWs. Much higher removal efficiencies for COD (92%), NH₄⁺-N (50%), and TN (50%) were obtained in the biochar-added SSFCW especially at the C/N ratio of 3 when comparing to CW without biochar. The higher pollutants removal ability of biochar-added SSFCWs was mainly attributed to the stronger adsorption ability in the porous biochar. However, poor nitrification was observed at various influent C/N ratios in SSFCWs with and without biochar due to lack of enough oxygen. This study supported that the use of biochar could increase the treatment performance in SSFCWs under various influent C/N ratios.