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25101. 题目: Generation and properties of aqu/nC 60 : the combined effects of humic acid, sunlight, and agitation intensity
文章编号: N20013118
期刊: Environmental Science and Pollution Research
作者: Xueyao Li, Guanghui Ding, Jing Zhang, Yingying Wang, Wanran Li, Chunchao Wang, Ruijuan Li, Zhanning Yang
更新时间: 2020-01-31
摘要: Once released into natural water, the environmental behavior and fate of C₆₀ could inevitably been affected by humic acid (HA), sunlight, and hydrodynamic conditions. However, the combined effects of these factors are not so clear. Therefore, in the present study, effects of HA, sunlight, and agitation intensity on generation and properties of aqu/nC₆₀ were investigated. The results indicated that HA could increase the concentration of aqu/nC₆₀ mainly through the steric hindrance effect. The higher agitation intensity led to higher concentrations of aqu/nC₆₀ and more efficient steric stabilization was formed by HA. Sunlight irradiation promoted the surface oxidization and consequently enhanced the dispersion of C₆₀. The relative order of the influence on the UV/vis concentration was sunlight > agitation intensity > HA. In addition, HA might not always enhance the dispersion of aqu/nC₆₀ due to light screening/ROS scavenging, over-coating, or chain-like bridging mechanism. Therefore, evaluating the environmental behavior and fate of C₆₀ should take these factors into account together.

25102. 题目: Enhanced reduction of sulfate and chromium under sulfate-reducing condition by synergism between extracellular polymeric substances and graphene oxide
文章编号: N20013117
期刊: Environmental Research
作者: Jia Yan, Weizhuo Ye, Xiaoshan Liang, Siji Wang, Jiehui Xie, Kengqiang Zhong, Min Bao, Jinbin Yang, Huijun Wen, Shugeng Li, Yongheng Chen, Ji-Dong Gu, Hongguo Zhang
更新时间: 2020-01-31
摘要: Microbial reduction of sulfate and metal were simultaneously enhanced in the presence of graphene oxide (GO)-like nanomaterials, however, the mechanism remained unclear. In this study, bio-reduction of Cr was compared between free-living bacterium BY7 and immobilized BY7 (BY-rGO) on reduced GO particles. The role of extracellular polymeric substances (EPS) and rGO material on reduction of sulfate and Cr was investigated. Cr(VI) was reduced to Cr(III) and elemental Cr by BY-rGO particles up to 51% and 28%, respectively. EPS produced by the bacterium BY7 mainly consisted of proteins, polysaccharides, nucleic acids and humic substances. Concentration of EPS was sharply increased (about 54%) with the addition of graphene oxide, while the composition of EPS components was strongly affected by the exposure to Cr. By removing surface EPS without breaking the cells, reduction activities of sulfate and chromium by both BY-rGO particles and free-living BY7 cells were decreased. In contrast, reduction of sulfate and Cr by the free-living BY7 cells was enhanced with external addition of extracted EPS. Based on electrochemical analysis, the reduction peak indicating enhanced electron transfer was lost after removing EPS. Moreover, the contribution of each EPS fractions on sulfate and Cr reduction followed an order of polysaccharides > proteins > humic substances. Therefore, microbial sulfate and Cr reduction processes in the presence of BY-rGO particles were enhanced by the increasing amounts of EPS, which likely mediated electron transfer during sulfate and Cr reduction, and relieved bacteria from metal toxicity. Nevertheless, the presence of rGO was crucially important for elemental Cr production under sulfate-reducing condition, which might contribute to lowering electric potential or reducing activation energy for Cr(III) reduction. This work provided direct evidences for enhancing sulfate and Cr reduction activities by supplement of EPS as an additive to increase treatment efficiency in environmental bioremediation.
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25103. 题目: Evidence for high organic carbon export to the early Cambrian seafloor
文章编号: N20013116
期刊: Geochimica et Cosmochimica Acta
作者: Meng Cheng, Chao Li, Chengsheng Jin, Haiyang Wang, Thomas J. Algeo, Timothy W. Lyons, Feifei Zhang, Ariel Anbar
更新时间: 2020-01-31
摘要: Oxygenation of the early Cambrian ocean is commonly ascribed to high organic export to the sediment due to the rise of algae and filter-feeding animals, but direct evidence of elevated export fluxes has been lacking to date. Here, we report an integrated proxy dataset (U-Mo isotopes, Fe speciation, and major and trace elements) for lower Cambrian black shales at Yuanjia on the Yangtze Platform (South China). These shales are characterized by high iron speciation ratios and Mo and U enrichments, indicating persistently euxinic water conditions during their deposition, but a broad range of δ⁹⁸Mo values (–0.10‰ to +1.94‰) implies strongly variable watermass sulfidity. High and variable nutrient element (Cu, Zn, Ni, Cd) enrichments at Yuanjia are consistent with elevated and variable organic productivity and export fluxes from the euphotic zone to the early Cambrian seafloor. The Yuanjia shales also exhibit super-heavy δ²³⁸U values (to +0.84‰) that cannot be explained by U reduction in sediment porewaters. We hypothesize that these values record a U reduction process within the water column, where U isotope fractionation can be much larger than in sediment porewaters. Such processes may have operated within a benthic organic flocculent layer at the sediment-water interface, a feature that is characteristic of high productivity systems with anoxic bottom waters. Furthermore, the coupling between δ²³⁸U, nutrient elements, and δ⁹⁸Mo suggests that elevated productivity levels were driven likely by episodic upwelling in early Cambrian oceans, supplying abundant nutrients for productivity and influencing H₂S concentrations in the water column. These observations, along with high organic carbon accumulation rates (5600 mg cm^-2 kyr^-1), are direct evidence of high organic export fluxes to the early Cambrian seafloor, thus providing key support for the hypothesis that enhanced organic export and burial triggered a major atmospheric-oceanic oxygenation event that stimulated the subsequent explosion of Cambrian life.

25104. 题目: Genomic and geochemical identification of the long-chain alkenone producers in the estuarine Lake Takahoko, Japan: Implications for temperature reconstructions
文章编号: N20013115
期刊: Organic Geochemistry
作者: Hiroto Kajita, Hideto Nakamura, Naohiko Ohkouchi, Naomi Harada, Miyako Sato, Shun Tokioka, Hodaka Kawahata
更新时间: 2020-01-31
摘要: Identifying the lacustrine haptophyte species that produce long-chain alkenones (LCAs) is essential for using alkenone unsaturation ratios to create lake water temperature reconstructions. We discovered LCAs in the brackish Lake Takahoko in northern Japan. The identity of LCA-producing species was investigated using 18S ribosomal DNA (rDNA) and organic geochemical analysis. Two distinct genetic groups, termed as Tak-A and Tak-B, were identified within the Group II haptophyte phylotype. Tak-A was closely related to Hap-A, which was obtained from Lake George, USA; and Tak-B was identified as Isochrysis galbana. Because Hap-A and Isochrysis galbana have similar temperature calibrations, Tak-A and Tak-B were also expected to share similar calibrations. Therefore, the changes of their relative abundances in the lake should not significantly disturb paleotemperature reconstructions. The alkenone temperature recorded in the surface sediment corresponded to the lake temperature in early to late summer. This is likely related to the haptophyte bloom season in Lake Takahoko suggesting that this lake may be a viable location for creating an lacustrine alkenone paleotemperature record.

25105. 题目: Glucose fermentation with biochar amended consortium: Sequential fermentations
文章编号: N20013114
期刊: Bioresource Technology
作者: Jia-Hsun Lu, Chuan Chen, Chihpin Huang, Shao-Yuan Leu, Duu-Jong Lee
更新时间: 2020-01-31
摘要: The aim of this work was to study sequential batch fermentation of glucose with a biological consortium amended with nine different biochars or with an activated carbon. The glucose fermentation was enhanced by carbon amendment, with activated carbon being more effective than biochars as cell carriers and electron conductors between functional species. The volatile fatty acid distributions were shifted in the consumption of the produced H₂ and CO₂. The types of biochars were irrelevant to glucose glycolysis and the subsequent H₂ and CO₂ consumption reactions. Biofilm growth affects the detailed mechanisms occurred in fermentation broth to the yielded volatile fatty acid distributions.

25106. 题目: Magnetic activated biochar nanocomposites derived from wakame and its application in methylene blue adsorption
文章编号: N20013113
期刊: Bioresource Technology
作者: Xinxin Yao, Lili Ji, Jian Guo, Shaoliang Ge, Wencheng Lu, Lu Cai, Yaning Wang, Wendong Song, Hailong Zhang
更新时间: 2020-01-31
摘要: In this work, magnetic wakame biochar nanocomposites for the first time had been synthesized to investigate their adsorption to methylene blue dye. As-prepared magnetic biochar samples were obtained by the impregnation method to load nickel on wakame biochar via one-step carbonization with activation agent KOH at 800 °C. The prepared samples were characterized by BET, XRD, FTIR, Raman, SEM, TEM and so on. The results exhibited that the maximum adsorption capacity of BW(Ni)0.5 to methylene blue could reach 479.49 mg/g at 20 °C. The adsorption behavior was more suitable for Langmuir isotherm equation and the kinetic data were most consistent with the pseudo second-order model. And also, the adsorption reaction was a spontaneous and endothermic process. After five cycles, it was found that BW(Ni)0.5 had a high adsorption capacity for methylene blue (117.58 mg/g). This study demonstrated that wakame biochar could have great potential in dye wastewater treatment.
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25107. 题目: Engineered rice-straw biochar catalysts for the production of value-added chemicals from furan
文章编号: N20013112
期刊: Chemical Engineering Journal
作者: Younghyun Lee, Sung Woo Lee, Yiu Fai Tsang, Yong Tae Kim, Jechan Lee
更新时间: 2020-01-31
摘要: In this study, biochars produced in two different atmospheres were used as catalysts for the valorization of furan, which derives from the hemicellulosic component of waste biomass. The biochars were produced from rice straw via pyrolysis in either an N₂ or a CO₂ environment (RSB-N₂ or RSB-CO₂) to modify their surface area and porosity. The biochars were then employed as a catalyst to support a bifunctional Ru–ReO_x catalyst. The biochar-supported Ru–ReO_x catalysts (Ru–ReO_x/RSB) were compared to a conventional activated charcoal (AC)-supported Ru–ReO_x catalyst (Ru–ReO_x/AC). The biochar-supported catalysts exhibited differences in reducibility and contained a different form of Re species compared to the AC-supported catalyst, which was attributed to the presence of alkali metal (e.g., potassium) in the biochar catalysts. The reducibility and metal dispersion on the support were also strongly associated with the atmosphere under which the biochar was produced. In particular, the Ru–ReO_x/RSB-CO₂ catalyst consumed 24% more hydrogen than did the Ru–ReO_x/RSB-N₂ catalyst within a temperature range of 250 to 560 °C. The biochar-supported catalysts had 12 times fewer surface metal sites than did the AC-supported catalyst due to their lower surface area. The reaction rate on a per-site basis for the conversion of furan to tetrahydrofuran and 1,4-butanediol was also measured for the catalysts. The Ru–ReO_x/RSB-N₂ catalyst was twice as active as the Ru–ReO_x/RSB-CO₂ catalyst and three times more active than the Ru–ReO_x/AC catalyst. This study thus proposes a straightforward strategy for modifying the catalytic properties of biochar catalysts and suggests a new application of biochar in the production of value-added chemicals from biomass and waste. The results also highlight the potential of biochar as a replacement for conventional catalysts in biorefineries.

25108. 题目: Critical study of crop-derived biochars for soil amendment and pharmaceutical ecotoxicity reduction
文章编号: N20013111
期刊: Chemosphere
作者: Magda Caban, Agnieszka Folentarska, Hanna Lis, Paulina Kobylis, Aleksandra Bielicka-Giełdoń, Jolanta Kumirska, Wojciech Ciesielski, Piotr Stepnowski
更新时间: 2020-01-31
摘要: In this study, biochars (BCs) produced from crops (straw and seeds) were tested for the applicability as additive to soils. The effect on pH, water capacity and cation exchange capacity of soil were tested. The ability for the sorption of pharmaceuticals (beta-blockers, anti-inflammatory drugs, sulfonamides, 17α-ethinylestradiol, carbamazepine, caffeine) using the batch sorption test was performed, and the effect of water pH was investigated. In addition, the metals removed from the biochar was analyzed as a potential toxicity factor. The mechanism of adsorption (Langmuir, Freundlich) was tested for sulfadimetoxine. The effect of the rye-derived biochar on water cress germination and the reduction of the sulfonamides toxicity to this plant was tested. The advantages of crop-derived biochar application to different soils (sand soil, clay soil and reference soil) was presented. It was found that tested BCs effectively increase the water capacity of soils, especially sand type soil, but in the same time it had increase the pH of pure-buffering soils. The driving force of pharmaceutical sorption was its ionization form - the highest sorption occurs for cations, medium for neutral forms, while the lowest sorption for anions. The opposite situation have been noted for desorption from biochar. The washing of biochars increases sorption for the neutral and anionic species, but not for the cations. The application of biochars into the soils can from one site protect the plants from toxic impact of sulfonamides, but from the other hamper the root prolongation by the pH increase.
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25109. 题目: Stabilization process and potential of agro-industrial waste on Pb-Contaminated soil around Pb–Zn mining
文章编号: N20013110
期刊: Environmental Pollution
作者: Yan Zhang, Xuemei Wang, Hongbing Ji
更新时间: 2020-01-31
摘要: Sawdust wastes were used as precursors to prepare adsorbents by combustion and pyrolysis for experimental and mechanism studies and determine the potential of biomass extracted from agro-industrial residues for Pb-polluted soil remediation. Pot experiments were conducted on contaminated soils near Pb–Zn mining with sawdust ash (SA) and sawdust biochar (SB) in different proportions and dosage ratios. Studies have indicated that the application of biomass materials can enhance the adsorption, complexation and precipitation of Pb cations in soil and reduce the mobility of Pb. The concentrations of SPLP-Pb and DTPA-extractable Pb in amended soils were the lowest under 1% 1:2 and 5% 1:1 treatment, respectively. Results of fraction extraction and XANES analysis showed that the materials change the main forms of Pb in soil. Moreover, the binding behavior of Pb with organic matter increases the proportion of Pb (Ac)₂, leading to the transformation of high toxicity Pb-compounds into precipitates and complexes. The remediation methods of 2% 1:2 and 5% 1:2 were better than those of other methods in stabilizing Pb in soil. This study indicated that heat-treated sawdust can be used for Pb-polluted soil remediation, which is a type of environmental remediation measure with considerable ecological potential.
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25110. 题目: Methyl bromide production from dissolved organic matter under simulated sunlight irradiation, and the important effect of ferric ions
文章编号: N20013109
期刊: Environmental Science: Processes Impacts
作者: Hui Liu, Tong Tong, Yingying Pu, Xiaomei Zhu, Bing Sun, Zhaowei Wang, ZhiYu Yan
更新时间: 2020-01-31
摘要: The oceans play an important role in the biogeochemical cycle of methyl bromide (CH3Br), not only the sinks but also the sources. However, many uncertainties exist regarding the way of CH3Br generation in marine environment. To illustrate the possibility of photochemical formation of CH3Br in saline water, its generation in bromide aqueous solution containing humic acid (HA) and ferric ions (Fe(III)) was investigated. CH3Br was obviously generated after irradiation, and its amounts increased with increasing of HA concentration from 0.82 to 12.2 mgC L-1. Fe(III) significantly promoted CH3Br production, and the described production process in the presence of Fe(III) was pH-dependent, decreasing with the increase of pH. Finally, concentrations of CH3Br in natural coastal seawater and seawater with HA were measured, and the results showed that CH3Br was significantly generated under irradiation. Our results suggest that photochemical process of dissolved organic matter may be one source of CH3Br in marine environment.

25111. 题目: No effect of pyrolysis temperature and feedstock type on hydraulic properties of biochar and amended sandy soil
文章编号: N20013108
期刊: Geoderma
作者: Wietse Wiersma, Martine J. van der Ploeg, Ian J.M.H. Sauren, Cathelijne R. Stoof
更新时间: 2020-01-31
摘要: Biochar has been lauded as a cure-all for improving water availability in soils. Yet the effect of pyrolysis temperature and feedstock type on biochar hydraulic properties and its subsequent effects on soils are not well known. We therefore systematically studied water retention, saturated hydraulic conductivity (K_sat) and hydrophobicity of 12 standard biochars (six feedstocks and two pyrolysis temperatures) developed by the UK Biochar Research Centre. The hydraulic properties were determined for pure crushed biochar, as well as for a sandy soil amended with 10 t ha⁻¹ biochar (assessed three times over a period of 15 months). For pure biochar, the effect of feedstock-temperature treatments on the water retention curve was negligible. Rice husk at a pyrolysis temperature of 700 °C had a significantly lower saturated water content, plant available water content and K_sat than all other biochar treatments. This can be attributed to its severe hydrophobicity: while all other treatments were non-hydrophobic and rice husk at 550 °C and Miscanthus straw at 550 °C were both strongly hydrophobic, rice husk at 700 °C was severely hydrophobic. Incorporation of the biochar into a sandy soil did not significantly influence soil water retention, saturated hydraulic conductivity and hydrophobicity. There were also no significant differences between the biochar treatments. These results indicate that except for rice husk at 700 °C the different biochar feedstock types and pyrolysis temperatures yield surprisingly similar material in terms of hydraulic characteristics. Improved soil hydrology should not be a main reason to apply biochar on sandy soils, but if biochar is applied differences in hydrophobicity should be considered.
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25112. 题目: Bacterially-assisted recovery of cadmium and nickel as their metal sulfide nanoparticles from spent Ni–Cd battery via hydrometallurgical route
文章编号: N20013107
期刊: Journal of Environmental Management
作者: Siddhartha Paul, Arvind Kumar Shakya, Pranab Kumar Ghosh
更新时间: 2020-01-31
摘要: Soaring demand for technology metals (e.g., Cd, Ni) and its ever-depleting primary resources ask for alternative recovery from secondary sources. Ni–Cd battery is one such source that can abridge the gap between demand and supply of such metals. Biogenic recovery, being environmentally benign, is explored for Cd and Ni recovery to manage the menace of spent Ni–Cd battery. Studies with 20, 40 and 60 mg/L Cd²⁺ initial concentrations in batch mode (in triplicates) at pH 7.0 ± 0.2, 30 ± 0.5 °C and 120 rpm were conducted using sulfate-reducing bacteria for 10 days. Analysis of extracellular polymeric substance revealed that protein secretion was enhanced, thereby forming Cd-EPS binding. Biosolids were collected and freeze-dried for morphological analysis viz. FESEM/EDX, PXRD and TEM, which revealed the formation of CdS nanoparticles (JCPDS card #00-042-1411) in range of 2–6 nm. Similarly, combined effect with 5, 10 and 20 mg/L Ni²⁺ at 20 mg/L Cd²⁺ were also investigated. Furthermore, to test the efficacy for real field application, spent Ni–Cd battery was dismantled and its powder was characterized, digested with concentrated HCl at 70 °C and was fed in batch mode after cooling, wherein nanoparticles of Ni and Cd sulfides were formed that has potential as semi-conducting material.
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25113. 题目: The characterization of arsenic biotransformation microbes in paddy soil after straw biochar and straw amendments
文章编号: N20013106
期刊: Journal of Hazardous Materials
作者: Yu-Ping Yang, Xian-Jin Tang, Hong-Mei Zhang, Wang-Da Cheng, Gui-Lan Duan, Yong-Guan Zhu
更新时间: 2020-01-31
摘要: Straw biochar and straw application to paddy soil dramatically altered arsenic (As) biogeochemical cycling in soil-rice system, but it remains unknown how As biotransformation microbes (ABMs) contribute to these processes. In this study, rice pot experiments combining terminal restriction fragment length polymorphism (T-RFLP) analysis and clone library were performed to characterize ABMs. Through linear discriminant analysis (LDA) effect size (LEfSe) and correlation analysis, results revealed that arrA-harbouring iron-reducing bacteria (e.g., Geobacter and Shewanella) and arsC-harbouring Gammaproteobacteria (e.g., fermentative hydrogen-producing and lignin-degrading microorganisms) potentially mediated arsenate (As(V)) reduction under biochar and straw amendments, respectively. Methanogens and sulfate-reducing bacteria (SRB) carrying arsM gene might regulate methylated As concentration in soil-rice system. Network analysis demonstrated that the association among ABMs in rhizosphere was significantly stronger than that in bulk soil. Arsenite (As(III)) methylators carrying arsM gene exhibited much stronger co-occurrence pattern with arsC-harbouring As(V) reducers than with arrA-harbouring As(V) reducers. This study would broaden our insights for the dramatic variation of As biogeochemical cycling in soil-rice system after straw biochar and straw amendments through the activities of ABMs, which could contribute to the safe rice production and high rice yield in As-contaminated fields.
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25114. 题目: Biodegradable organic matter-containing ammonium wastewater treatment through simultaneous partial nitritation, anammox, denitrification and COD oxidization process
文章编号: N20013105
期刊: Science of The Total Environment
作者: Yan Guo, Qigui Niu, Takumi Sugano, Yu-You Li
更新时间: 2020-01-31
摘要: For both nitrogen and COD removal from biodegradable organic matter (BOM)-containing ammonium wastewater, the simultaneous partial nitritation, anammox, denitrification and COD oxidization (SNADCO) process is a promising solution. In this study, with the stable influent ammonium concentration of 250.0 mg/L (nitrogen loading rate of 0.5 kg/m³/d) and the variation of influent COD/NH₄⁺-N (C/N) ratio from 0.0 to 1.6, the performance of the SNADCO process in a one-stage carrier-packing airlift reactor with continuous mode was investigated for the first time. The results showed that until the C/N ratio of 0.8, both the well nitrogen and COD removal targets could be reached. Mass balance calculations indicated that the average nitrogen removal efficiency (NRE) of 80.9% achieved at the C/N ratio of 0.8 were due to both the anammox and denitrification pathways. Correspondingly, the achieved average COD removal efficiency of 94.6% was attributed to both the denitrification and COD oxidization pathways. Based on the specific sludge activity tests and Fluorescence in Situ Hybridization observation, anammox and denitrification bacteria were mainly distributed in the biofilm sludge, while ammonium oxidizing bacteria and ordinary heterotrophic organisms were mainly in the suspended sludge. At the C/N ratio of 1.6, the washout of suspended sludge became serious while the biofilm sludge was well retained, resulting in inefficient nitritation and a subsequent decrease in NRE. The microbial interaction analysis provided a clear explanation of the performance change of the SNADCO process under different C/N ratios. This research enriches the knowledge of the SNADCO process in BOM-containing ammonium wastewater treatment.
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25115. 题目: Redox state of microbial extracellular polymeric substances regulates reduction of selenite to elemental selenium accompanying with enhancing microbial detoxification in aquatic environments
文章编号: N20013104
期刊: Water Research
作者: Xin Zhang, Wen-Yuan Fan, Mu-Cen Yao, Chuan-Wang Yang, Guo-Ping Sheng
更新时间: 2020-01-31
摘要: In nature, many microorganisms show resistance to toxic selenite by reducing selenite to non-soluble and low toxic elemental selenium. Extracellular polymeric substances (EPS), a high-molecular-weight biopolymers originated from microbial metabolism, contain many reducing groups and can induce reductive transformation of pollutants. However, the roles of EPS and its redox state in reductive detoxification or reduction removal of selenite, respectively, remain unknown yet. Herein, the reduction of selenite by different sources of EPS was investigated. Selenite was proved to be reduced by EPS and partly transformed to elemental selenium. The formed elemental selenium was mainly selenium nanoparticles confirmed by transmission electron microscopy coupled with energy dispersive spectroscopy. The redox state of EPS governed selenite reduction and elemental selenium formation, and the reduced state of EPS was in favor of selenite reduction. Dissolved oxygen concentration in water regulated EPS redox state and influenced selenite reduction. The thiols, aldehyde and phenolic groups in EPS were responsible for selenite reduction. Under selenite stress, EPS was capable of increasing cell survivability by enhancing microorganisms-mediated selenite reduction. This work revealed the previously undiscovered roles of EPS in selenite reduction and elemental selenium formation in aquatic environments and also suggested a possible crucial role of EPS in selenium biogeochemical cycle.
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25116. 题目: Impact of groundwater quality and associated byproduct formation during UV/hydrogen peroxide treatment of 1,4-dioxane
文章编号: N20013103
期刊: Water Research
作者: Cheng-Shiuan Lee, Arjun K. Venkatesan, Harold W. Walker, Christopher J. Gobler
更新时间: 2020-01-31
摘要: In this study, a semi-batch, bench-scale UV/hydrogen peroxide (UV/H₂O₂) advanced oxidation process system was used to investigate how typical groundwater quality parameters (pH, alkalinity, natural organic matter (NOM), nitrate, and iron) influence the treatment of 1,4-dioxane. Deionized (DI) water spiked with 1,4-dioxane (100 μg L⁻¹), treated using H₂O₂ (10 mg L⁻¹) in a commercially available UV system (40 W low-pressure lamp) showed an UV fluence-based first-order rate constant (k’) and electrical energy-per-order (EEO) of 4.32✕10⁻³ cm²-mJ⁻¹ and 0.15 kWh-m⁻³-order⁻¹, respectively. The most abundant byproduct generated in spiked-DI water was oxalic acid (up to 55 μg L⁻¹), followed by formic and acetic acids. The k’ showed no significant difference at pH ranging from 5 to 7 and at low alkalinity concentrations (<20 mg-CaCO₃ L⁻¹), typical of sandy aquifers. The k’ declined by up to 85% with increasing NOM concentration. Elevated production (up to ∼400% increase) of aldehydes and organic acids was observed in NOM-spiked water, implying that NOM is a significant byproduct precursor during UV/H₂O₂ treatment. High NO₃⁻ concentration (10 mg-N L⁻¹) in source water reduced the k’ by 25%, while no significant impact was observed at lower concentrations (<2 mg-N L⁻¹). Addition of Fe(II) at 0.5 mg-L⁻¹ resulted in an instantaneous Fenton-reaction-assisted removal of ∼10% 1,4-dioxane in the presence of H₂O₂, but did not enhance the performance of UV/H₂O₂ treatment over time. In contrast, both Fe(II) and Fe(III) addition lowered the k’ by 15–27%. The decline of k’ observed in these experiments was attributed to reduced UVT (Fe), ^.OH radical scavenging (pH), or both (NO₃⁻, NOM). Treatment of groundwater samples collected from three 1,4-dioxane-contaminated wells located in Long Island, NY, showed k’ values of 13–40% lower than what was observed for DI water due to radical scavenging from a combination of high NO₃⁻ and NOM in the samples. A multiple linear-regression model, developed using water quality data as model input, showed good agreement with field observations (paired t-test: p > 0.05) in predicting k’ for the removal of 1,4-dioxane from groundwater. This study provides the first systematic evaluation of the impacts of groundwater quality on UV/H₂O₂ process to remove environmentally relevant levels of 1,4-dioxane and reports standardized performance-related parameters to aid in the design and evaluation of full-scale systems.
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25117. 题目: Dissolved organic matter in a tropical saline-alkaline lake of the East African Rift Valley.
文章编号: N20013102
期刊: Water Research
作者: A. Butturini, P. Herzsprung, J. Lechtenfeld O, S. Venturi, S. Amalfitano, Vazquez E, N. Pacini, D.M. Harper, F. Tassi, S. Fazi
更新时间: 2020-01-31
摘要: Saline-alkaline lakes of the East African Rift are known to have an extremely high primary production supporting a potent carbon cycle. To date, a full description of carbon pools in these lakes is still missing. More specifically, there is not detailed information on the quality of dissolved organic matter (DOM), the main carbon energy source for heterotrophs prokaryotes. We report the first exhaustive description of DOM molecular properties in the water column of a meromictic saline-alkaline lake of the East African Rift. DOM availability, fate and origin were studied either quantitatively, in terms of dissolved organic carbon (DOC) and nitrogen (DON) or qualitatively, in terms of optical properties (absorbance) and molecular characterization of solid-phase extracted DOM (SPE-DOM) through negative electrospray ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS). DOM availability was high (DOC ∼ 8.1 mM in surface waters) and meromixis imprinted a severe quantitative and qualitative change on DOM pool. At the surface, DOM was rich in aliphatic and moderately in aromatic molecules and thus mirroring autochthonous microbial production together to photodegradation. At the bottom changes were extreme: DOC increased up to 5 times (up to 50 mM) and, molecular signature drifted to saturated, reduced and non-aromatic DOM suggesting intense microbial activity within organic sediments. At the chemocline, DOC was retained indicating that this interface is a highly reactive layer in terms of DOM processing. These findings underline that saline-alkaline lakes of the East African Rift are carbon processing hot spots and their investigation may broaden our understanding of carbon cycling in inland waters at large.

25118. 题目: Photochemical degradation of nebivolol in different natural organic matter solutions under simulated sunlight irradiation: Kinetics, mechanism and degradation pathway
文章编号: N20013101
期刊: Water Research
作者: Jieqiong Wang, Kai Wang, Yuchen Guo, Junfeng Niu
更新时间: 2020-01-31
摘要: Nebivolol (NEB) is widely used for the treatment of hypertension and chronic heart failure and has become an ubiquitous emerging organic pollutant. It has been shown to undergo direct photolysis, but the role of DOM in its degradation kinetics and mechanism is not well understood. In this study, we studied the photochemical behavior of NEB in the presence of seawater DOM (SW-DOM) and freshwater DOM (SRNOM) under simulated sunlight irradiation. SW-DOM had a promotion effect on NEB photodegradation, whereas SRNOM retarded its photolytic transformation. After eliminating the influence of light screening, we found that the indirect photodegradation rate of NEB in the presence of SRNOM was lower than that in the presence of SW-DOM. Results show that the indirect photodegradation pathway occurred by reaction with triplet-excited DOM (³DOM*). The second-order rate constants for ³SW-DOM* and ³SRNOM* reaction with NEB are 3.7 × 10⁹ M⁻¹ s⁻¹ and 3.7 × 10⁸ M⁻¹ s⁻¹, respectively. The electron donating capacity of SRNOM is higher than that of SW-DOM, indicating that SRNOM may contain more activated phenolic moieties. SRNOM may thus have higher antioxidant activity, leading a higher inhibitory effect on NEB photodegradation. A total of six degradation products were identified in the absence and presence of DOM by HPLC-ESI-MS/MS. The substitution of F by OH-groups and further oxidation a OH-group in the lateral chain to a ketone, and cleavage of N–C bond by the attack of ³DOM* are here proposed as the main degradation pathways.
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25119. 题目: Spatiotemporal Patterns of Mineral and Organic Matter Deposition Across Two San Francisco Bay-Delta Tidal Marshes
文章编号: N20013013
期刊: Wetlands
作者: Kevin J. Buffington
更新时间: 2020-01-30
摘要: Sediment deposition in tidal wetlands is a critical process that determines whether vertical growth will keep pace with sea-level rise. However, more information is needed on how sediment deposition varies spatially and temporally across wetlands, including the effects of elevation, tidal inundation, vegetation, and weather. We investigated variation in sediment deposition due to season, distance from channel, channel size, and vegetation composition at low and high salinity tidal marshes in the San Francisco Bay-Delta Estuary, California using sediment traps deployed monthly between December 2015 and November 2016. Over the course of the year, sediment deposition ranged widely (1.4 – 174.0 kg m−2 yr−1) and averaged 19.5 ± 3.5 kg m−2 yr−1. Deposition increased with flooding duration, decreased with increasing distance from channels, and was highest during the spring and early summer. Higher wind speeds during the spring may have driven re-suspension from mudflats, promoting deposition. Ratios of organic-to-mineral deposition were twice as high at the fresher site and were correlated with differences in vegetation composition between sites. Our results suggest that seasonality, distance from sediment source, salinity regime, and channel size are important sources of spatiotemporal variation in deposition. These results are relevant to accretion sampling and wetland restoration design.

25120. 题目: Soil organic matter attenuates the efficacy of flavonoid-based plant-microbe communication
文章编号: N20013012
期刊: Science Advances
作者: Ilenne Del Valle, Tara M. Webster, Hsiao-Ying Cheng, Janice E. Thies, André Kessler, Mary Kaitlyn Miller, Zachary T. Ball, Kevin R. MacKenzie, Caroline A. Masiello, Jonathan J. Silberg, Johannes Lehmann
更新时间: 2020-01-30
摘要: Plant-microbe interactions are mediated by signaling compounds that control vital plant functions, such as nodulation, defense, and allelopathy. While interruption of signaling is typically attributed to biological processes, potential abiotic controls remain less studied. Here, we show that higher organic carbon (OC) contents in soils repress flavonoid signals by up to 70%. Furthermore, the magnitude of repression is differentially dependent on the chemical structure of the signaling molecule, the availability of metal ions, and the source of the plant-derived OC. Up to 63% of the signaling repression occurs between dissolved OC and flavonoids rather than through flavonoid sorption to particulate OC. In plant experiments, OC interrupts the signaling between a legume and a nitrogen-fixing microbial symbiont, resulting in a 75% decrease in nodule formation. Our results suggest that soil OC decreases the lifetime of flavonoids underlying plant-microbe interactions.