81. 题目: Stream dissolved organic matter in permafrost regions shows surprising compositional similarities but negative priming and nutrient effects
期刊: Global Biogeochemical Cycles
作者: Ethan Wologo, Sarah Shakil, Scott Zolkos, Sadie Textor, Stephanie Ewing, Jane Klassen, Robert G. M. Spencer, David C. Podgorski, Suzanne E. Tank, Michelle A. Baker, Jonathan A. O’Donnell, Kimberly P. Wickland, Sydney S. W. Foks, Jay P. Zarnetske, Joseph Lee‐Cullin, Futing Liu, Yuanhe Yang, Pirkko Kortelainen, Jaana Kolehmainen, Joshua F. Dean, Jorien E. Vonk, Robert M. Holmes, Gilles Pinay, Michaela M. Powell, Jansen Howe, Rebecca J. Frei, Samuel P. Bratsman, Benjamin W. Abbott
摘要: Permafrost degradation is delivering bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total fluvial DOM and nutrient fluxes, they could influence food webs and net ecosystem carbon balance via priming or nutrient effects that destabilize background DOM. We investigated how addition of biolabile carbon (acetate) and inorganic nutrients (nitrogen and phosphorus) affected DOM decomposition with 28‐day incubations. We incubated late‐summer stream water from 23 locations nested in seven northern or high‐altitude regions in Asia, Europe, and North America. DOM loss ranged from 3% to 52%, showing a variety of longitudinal patterns within stream networks. DOM optical properties varied widely, but DOM showed compositional similarity based on FT‐ICR MS analysis. Addition of acetate and nutrients decreased bulk DOM mineralization (i.e. negative priming), with more negative effects on biodegradable DOM but neutral or positive effects on stable DOM. Unexpectedly, acetate and nutrients triggered breakdown of colored DOM (CDOM), with median decreases of 1.6% in the control and 22% in the amended treatment. Additionally, the uptake of added acetate was strongly limited by nutrient availability across sites. These findings suggest that biolabile DOM and nutrients released from degrading permafrost may decrease background DOM mineralization, but alter stoichiometry and light conditions in receiving waterbodies. We conclude that priming and nutrient effects are coupled in northern aquatic ecosystems, and that quantifying two‐way interactions between DOM properties and environmental conditions could resolve conflicting observations about the drivers of DOM in permafrost zone waterways.
82. 题目: Soil organic carbon becomes newer under warming at a permafrost site on the Tibetan Plateau
期刊: Soil Biology and Biochemistry
作者: Ruiying Chang, Shuguang Liu, Leiyi Chen, Na Li, Haijian Bing, Tao Wang, Xiaopeng Chen, Yang Li, Genxu Wang
摘要: Permafrost areas are experiencing fast and dramatic changes under global warming. Increased primary production and stimulated microbial activity have been widely observed in warming permafrost. However, the fate of permafrost soil organic carbon (SOC) remains elusive, and the potential mechanisms underlying warming-mediated SOC formation and old C decomposition are poorly understood. Here, using in situ six-year manipulative warming experiments with two scenarios (+2.4 °C and +4.9 °C for lower and higher scenarios, respectively, above the ambient temperature) at a permafrost site in the Tibetan Plateau, we observed that soil C sink increased in the surface 5 cm layer under the two warming scenarios. SOC exhibited a linear increase with warming duration at rates of 6.8% and 6.4% annually in the silt & clay fractions and aggregates, respectively. Warming-induced accumulations of SOC in the aggregates and silt & clay fractions were contributed mainly by plant-derived C and minorly by microbial necromass. However, the increased input of new plant-derived C was accompanied with an increasing loss of old C via enhanced respiration under warming, likely due to the mobilization and degradation of C in the aggregates and silt & clay fractions. Our study provides field-based evidence of the enhanced SOC accumulation in the Tibetan permafrost regions under warming, and improves process-based understanding of warming-induced new plant-derived C that could replace the protected old C in the aggregates and silt & clay fractions.
83. 题目: A lipid biomarker investigation of the sources and distribution of organic matter in river-influenced shelf sediments of NE Brazil
期刊: Organic Geochemistry
作者: Renato S. Carreira, Ana Cecília R. de Albergaria-Barbosa, Maria de Lara P. M. Arguelho, Carlos A. B. Garcia
摘要: A better understanding of the sources – continental or marine – and distribution of organic matter (OM) in shelf sediments of areas under distinct natural and anthropogenic forces is essential to obtain a global view of the carbon cycle. In this study, we evaluated the influence of river discharge on the OM accumulation pattern in a portion of the NE Brazilian continental margin (10–15 °S) by considering a suite of lipid biomarkers (sterols, n-alcohols, phytol and taraxerol) in surface sediments. A total of 36 samples were collected adjacent to river mouths representing drainage basins of varying size and representing different human intervention levels, namely the São Francisco, Vaza Barris, Sergipe and Piauí-Real rivers. The average concentration of the total quantified lipids was 3.77 ± 1.93 µg g-1, with the lowest values detected at the São Francisco River pro-delta. This result seems to reflect the reductions in the São Francisco river flow during the last decades caused by human interventions (diverse water use and urbanization, among others) and climate change (reduced precipitation) along its drainage basin, which seems to affect other smaller basins to a lesser extent. Our findings highlight that human interventions and climate change are relevant drivers for biogeochemical processes even in shelves receiving the flow from small to medium rivers in Brazil, which agree with other records worldwide. Finally, we hope the data presented herein contribute to the development of a management system based on a watershed-coastal ocean scaling and socio-environmental perspective for the Sergipe and Alagoas shelf.
84. 题目: Selective removal of pharmaceuticals and personal care products from water by titanium incorporated hierarchical diatoms in the presence of natural organic matter
期刊: Water Research
作者: Yan Li, Chiqian Zhang, Zhiqiang Hu
摘要: Natural organic matter (NOM), such as humic acids, fulvic acids, and tannic acids, is ubiquitous in water bodies and hinders the photodegradation of pharmaceuticals and personal care products (PPCPs). We prepared titanium incorporated hierarchical diatoms as a novel photocatalyst to selectively remove PPCPs (triclosan, bisphenol A or BPA, and N, N-Diethyl-meta-toluamide or DEET) in the presence of NOM (humic acid). Diatom (Stephanodiscus hantzschii) grown in a titanium(IV) bis(ammonium lactato) dihydroxide solution integrated 7.2% ± 1.4% (mass fraction) of titanium in their cell wall and formed silica-titania frustules. The photodegradation of triclosan, BPA, and DEET by both silica-titania frustules and titania nanopowder (a control photocatalyst) follows pseudo-first-order kinetics. Under ultraviolent light irradiation, the titanium-content-normalized pseudo-first-order removal rate constants of triclosan, BPA, and DEET by silica-titania frustules were 3, 4, and 4-times those by titania nanopowder, respectively, at a humic acid concentration of 10 mg•L−1. Incorporation of titanium did not alter the morphology and hierarchical nano/microstructures of the diatom. The silica-titania frustules were rich in nanopores with a diameter of 20 ± 4 nm (mean ± standard deviation), allowing PPCPs with a small molecular weight (typically < 600 g•mol−1) to pass through while efficiently rejecting NOM with high molecular weights. The silica-titania frustules with hierarchical nano/microstructures served as a prefiltration unit by selectively allowing PPCPs to pass through the nanopores and are therefore promising for photodegradation and environmental remediation applications.
85. 题目: Pedoenvironmental indicators of soil in Western Amazonia, Brazil
期刊: Environmental Monitoring and Assessment
作者: Ivanildo Amorim de Oliveira, Milton César Costa Campos, Diego Silva Siqueira, Ludmila de Freitas, Renato Eleotério de Aquino, Flavio Pereira de Oliveira
摘要: This study aimed to ascertain what soil attributes may be an indicator of natural and anthropic pedogenic changes in top grassland (TG), low grassland (LG), ecotone zone (EZ), and forest (F) in Western Amazonia. Twenty samples of the diagnostic horizons were collected from the studied pedoenvironments: TG (A 0.0–14 and Bi 0.30–0.66 m); LG (A 0.0–0.15 and Cg1 0.27–0.80 m); EZ (A 0.0–0.15 and Bi 0.32–0.50 m); and forest (F) (A1 0.0–0.15 and Bt1 0.67–0.10 m). Sand, silt, clay, particle density (PD),soil bulk density (BD),saturated soil hydraulic conductivity, calcium (Ca), magnesium (Mg), exchangeable aluminum (Al3+), potassium (K), sodium (Na), phosphorus (P), pH in water and KCl, and organic matter (OM) contents were calculated and submitted to variance analysis. LG is more related to OM and clay than SHC value. These same attributes characterized TG. EZ is highlighted by its higher values and relationship with Al and K. It was concluded that for TG, LG, EZ, and F top soil layers, 28% of natural and anthropic changes can be identified based on sand, clay, pH in KCl, and OM data; on the other hand, subsurface 23% of determinations can be attributed to pH in H2O, Al, Na, and sand.
86. 题目: How will a drier climate change carbon sequestration in soils of the deciduous forests of Central Europe?
作者: István Fekete, Imre Berki, Kate Lajtha, Susan Trumbore, Ornella Francioso, Paola Gioacchini, Daniela Montecchio, Gábor Várbíró, Áron Béni, Marianna Makádi, Ibolya Demeter, Balázs Madarász, Katalin Juhos, Zsolt Kotroczó
摘要: Global warming is accompanied by increasing water stress across much of our planet. We studied soil biological processes and changes in soil organic carbon (SOC) storage in 30 Hungarian oak forest sites in the Carpathian Basin along a climatic gradient (mean annual temperature (MAT) 9.6–12.1 °C, mean annual precipitation (MAP) 545–725 mm) but on similar gently sloped hillsides where the parent materials are loess and weathered dust inputs dating from the end of the ice age. The purpose of this research was to understand how a drying climate, predicted for this region, might regulate long-term SOC sequestration. To examine the effects of decreasing water availability, we compared soil parameters and processes in three categories of forest that represented the moisture extremes along our gradient and that were defined using a broken-stick regression model. Soil biological activity was significantly lower in the driest (“dry”) forests, which had more than double the SOC concentration in the upper 30 cm layer (3.28 g C/100 g soil ± 0.11 SE) compared to soils of the wettest (“humid”) forests (1.32 g C/100 g soil ± 0.09 SE), despite the fact that annual surface litter production in humid forests was ~ 37% higher than in dry forests. A two-pool SOM model constrained to fit radiocarbon data indicates that turnover times for fast and slow pools are about half as long in the humid soil compared to the dry soil, and humid soils transfer C twice as efficiently from fast to slow pools. Enzyme activity and fungal biomass data also imply shorter turnover times associated with faster degradation processes in the soils of humid forests. Thermogravimetry studies suggest that more chemically recalcitrant compounds are accumulating in the soils of dry forests. Taken together, our results suggest that the predicted climate drying in this region might increase SOC storage in Central European mesic deciduous forests even as litter production decreases.
87. 题目: Promoting extracellular polymeric substances to alleviate phenol toxicity in Arthrospira platensis at high carbon dioxide concentrations
期刊: Journal of Cleaner Production
作者: Yanxia Zhu, Jun Cheng, Ze Zhang, Hui Li, Zhenyi Wang
摘要: Carbon dioxide (CO2) capture combined with phenol degradation by cyanobacteria can sequester carbon back to biosphere and purify coal-chemical flue gas. It was found that intracellular damages caused by phenol was alleviated in Arthrospira platensis under high CO2 concentrations. A high CO2 concentration locally around the cells promoted secretion of extracellular polymeric substances (EPS). The stimulated humic acid-like organics (main ingredients in EPS observed by excitation-emission matrix fluorescence spectroscopy) with strong adhesive properties, which worked as protective barriers to limit phenol transportation into the cells and created a microenvironment suitable for cells growth. The activity of phenol hydroxylase released into extracellular matrix was increased by 112.7% to enhance extracellular phenol degradation under 99.99 vol.% CO2. The decreased abundances of intracellular superoxide dismutase and malondialdehyde suggested that elevated CO2 level protected cells by alleviating phenol toxicity and regulating intracellular redox state. Furthermore, the effective quantum yield of photosystem II was promoted by reducing the damage on photosynthetic membranes under phenol stress, leading to an increased biomass productivity by 35.1% during the first four days under 99.99 vol.% CO2. These results have provided a new approach to simultaneously improve carbon-capture and flue gas purification.
88. 题目: A Fenton-like system of biochar loading Fe-Al layered double hydroxides (FeAl-LDH@BC) / H2O2 for phenol removal
作者: Xiaoliang Fan, Qingqing Cao, Fanyue Meng, Bing Song, Zhongqiang Bai, Yan Zhao, Dandan Chena, Yan Zhou, Min Song
摘要: FeAl-layered double hydroxide (FeAl-LDH) supported by char was synthesized using the hydrothermal method in order to activate hydrogen peroxide (H2O2) to degrade phenol. The effects of char type, char synthesis amount, and several important parameters on the degradation were investigated. In addition, the physicochemical properties of [email protected] were revealed by instruments including the transmission electron microscope (TEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR). The results showed that the degradation efficiency of phenol (80 mg/L) by [email protected] was 85.28% at a pH of 3 and H2O2 concentration of 400 mg/L, and exhibited good reusability with a small amount of iron leaching. Electron paramagnetic resonance (EPR) and radical quenching results indicated that ·OH radicals were the main participant during the degradation process, and XRD and FTIR spectra showed that FeAl-LDH was dissolved and rebuilt during the degradation process, and a small amount of iron was leached out resulting in the homogeneous catalysis. Hence, both homogeneous and heterogeneous processes occurred in the phenol oxidation process. Further soil remediation experiments showed that [email protected] could also effectively degrade phenol in soil, although the efficiency was lower than that in solution.
89. 题目: Responses of bacterial communities and organic matter degradation in surface sediment to Macrobrachium nipponense bioturbation
期刊: Science of The Total Environment
作者: Yiran Hou, Bing Li, Gongcheng Feng, Chengfeng Zhang, Jie He, Haidong Li, Jian Zhu
摘要: The excessive accumulation of organic matter (OM) in sediments in aquaculture ponds is a potential environmental threat due to the risk of endogenous water pollution and eutrophication. From the perspective of inhibiting OM accumulation to prevent endogenous water pollution, the present study investigated the OM degradation states, variations of bacterial communities and basic environmental factors in sediments with/without Macrobrachium nipponense treatment/control groups in triplicate for effects of bioturbation on OM degradation in 90-day incubation. The total organic carbon (TOC) and total nitrogen (TN) in the M. nipponense treatment were higher than in the control at the 30th and 60th days, while no significant differences between treatment and control were found at the end of the experiment. Significantly higher oxidation-reduction potential (ORP) and more extensively degraded OM were observed in the M. nipponense treatment. Eleven significantly differential bacterial taxa were enriched in the sediments of M. nipponense treatment, of which eight (Actinobacteria, Chitinophagales, Chitinophagaceae, Flavihumibacter, Marinilabiliaceae, Cytophaga xylanolytica group, Christensenellaceae, and Christensenellaceae R-7 group) were significantly correlated with at least two OM degradation indicators. The functional groups chemoheterotrophy, aerobic chemoheterotrophy, xylanolysis, ureolysis, and intracellular parasites were enhanced by M. nipponense and were negatively correlated with OM degradation indictors. Overall, the M. nipponense bioturbation effectively increased the ORP to provide better conditions for OM degradation, altered the taxonomic composition and functional groups to enhance the bacterial ability for OM degradation, and finally promoted the OM degradation of the surface sediment in an artificial aquaculture system.
90. 题目: Seasonal variations in the optical characteristics of dissolved organic matter in glacial pond water
期刊: Science of The Total Environment
作者: D. Vione, N. Colombo, D. Said-Pullicino, D. Bocchiola, G. Confortola, F. Salerno, G. Viviano, S. Fratianni, M. Martin, D. Godone, M. Freppaz
摘要: Large amounts of dissolved organic matter (DOM) are stored in mountain glaciers. However, few researches have analysed the optical characteristics of DOM in surface waters fed by mountain glaciers and their seasonal variations. In a pond fed by a glacier we observed simultaneous decreases in the dissolved organic carbon, and increases in both absorbance at 254 nm and specific absorption coefficient (SUVA254) during the ice-free season 2015. This behaviour differs from the typical behaviour of lake/pond water in summer, and from the trends observed in a nearby pond not fed by a glacier. The trends of DOM properties, main ions and water stable isotopes at the glacier-fed pond could be attributed to transient modifications of the subglacial hydrological system. Flushing of previously isolated pools of subglacially stored water, containing terrestrial DOM derived from glacially-overridden soil and vegetation, would be driven by intense rainfall events during the melting season. These findings suggest that heavy rainfall events during the melting season have the capability to transiently modify the characteristics of DOM in a glacial pond. These events may be further exacerbated in the future, as summer rainfall events in the Alps are predicted to increase due to global warming.
91. 题目: Photo-ammonification in surface water samples: mechanism and influencing factors
期刊: Science of The Total Environment
作者: Yanwen Yang, Peizhe Sun, Lokesh P. Padhye, Ruochun Zhang
摘要: Dissolved organic nitrogen (DON) accounts for a large proportion of the total aquatic nitrogen. Compared with dissolved inorganic nitrogen (DIN), the reactivity of DON has received limited attention. Photo-ammonification contributes significantly to the transformation of DON to DIN. However, information on the mechanism of this process is limited. This study investigated the photo-ammonification process of different natural surface water samples. The effects of seasons and rainfall on this process were explored, and the contributing factors were identified. Results showed that the seasonal effect on photo-ammonification differed for different water samples, whereas rainfall increased the rates of photo-ammonification for most of the lakes. The concentrations of reactive species, including triplet states of chromophoric dissolved organic matter (3CDOM*) and singlet oxygen (1O2), were found to be significantly correlated with water optical-parameters. Multivariable linear regression analysis (R2 = 0.617) revealed that the photo-ammonification of DON was mainly facilitated by 3CDOM* whereas 1O2 competed with 3CDOM* and showed an inhibiting effect. The components of dissolved organic matter (DOM) were identified by fluorescence excitation emission matrices coupled with parallel factor analysis and were found to be greatly influenced by the location. Allochthonous humic-like components were found to promote the production of reactive species while tryptophan-like component was found to be a reactive species consumer. This study revealed that the composition of DOM and the reactive species governed the rates of photo-ammonification.
92. 题目: Accumulation and characteristics of fluorescent dissolved organic matter in loess soil-based subsurface wastewater infiltration system with aeration and biochar addition
期刊: Environmental Pollution
作者: Wen Li, Chenglong Liang, Lu Dong, Xin Zhao, Haiming Wu
摘要: Subsurface wastewater infiltration systems (SWISs) have been widely used to treat rural domestic sewage. However, the low nitrogen removal and severe clogging problem always restrict the sustainability of SWISs for wastewater treatment. This study investigated the effects of aeration and biochar on the accumulation of nutrients and dissolved organic matter (DOM) in the substrate of loess soil-based SWISs for understanding the accumulation characteristics of DOM and the enhanced decontamination mechanism. The results showed that biochar addition could not improve the accumulation of nitrogen and phosphorus in the substrate, but could enhance denitrification (22%) via providing sufficient carbon for microorganisms. Moreover, the accumulation of organic matter in the substrate was also greatly affected. The DOM concentration of System D in the 40-60 cm layer reached 85.76 mg L-1, which indicated that biochar could release abundant DOM. Substrate DOM mainly contained humic acid-like and tryptophan-like substances. Moreover, the refractory macromolecular DOM components with high aromaticity and humification were found in the substrate below 60 cm of systems with biochar addition. This may be related to the DOM released by biochar and the extracellular polymeric substance (EPS) produced by microorganisms. It may affect the sustainability of the substrate to a certain extent, but fortunately that intermittent aeration could reduce this adverse effect. This research could provide new insights for preventing clogging and useful guidance for improving wastewater treatment performance in SWISs.
93. 题目: Relationship Between Dissolved Organic Matter and Phytoplankton Community Dynamics in a Human-impacted Subtropical River
期刊: Journal of Cleaner Production
作者: Qi Liu, Yulu Tian, Yang Liu, Ming Yu, Zhaojiang Hou, Kejian He, Hui Xu, Baoshan Cui, Yuan Jiang
摘要: Dissolved organic matter (DOM) is closely related to phytoplankton blooms, one of the most concerning environmental problems globally. DOM originates from phytoplankton production and metabolic activity and, in turn, can influence phytoplankton biomass and community structure. Therefore, clarifying the relationship between phytoplankton community dynamics and DOM has implications for bloom prevention and control as well as for aquatic ecosystem management. To understand this relationship further, we investigated phytoplankton communities at 110 sites in the dry and rainy seasons within the Dongjiang River basin, China, which is known for high rates of urbanization, industrialization, and agricultural intensification. The interaction between DOM (two humic-like DOM [C1 and C2] and two protein-like DOM [C3 and C4]) and phytoplankton community dynamics was investigated. Phytoplankton biomass and taxonomic composition were significantly related to C2, C3, and C4. The effect of C3 and C4 on phytoplankton taxonomic composition was prominent. C2 originating from agricultural wastewater increased phytoplankton biomass and changed phytoplankton taxonomic composition, whereas C1, originating from terrestrial soils and plants, did not stimulate phytoplankton biomass in rivers. There were clear change points, where phytoplankton abundance rapidly increased or decreased with changes in the concentrations of DOM components. Results suggested that DOM controls phytoplankton community dynamics and their relationship changes with variations in DOM chemical composition. DOM generated by anthropogenic activities may act as a potential warning of phytoplankton blooms.
94. 题目: Absorption properties and forcing efficiency of light-absorbing water-soluble organic aerosols: seasonal and spatial variability
期刊: Environmental Pollution
作者: Vikram Choudhary, Prashant Rajput, Tarun Gupta
摘要: Light-absorbing organic aerosols, also known as brown carbon (BrC), enhance the warming effect of the Earth's atmosphere. The seasonal and spatial variability of BrC absorption properties is poorly constrained and accounted for in the climate models resulting in a substantial underestimation of their radiative forcing estimates. This study reports seasonal and spatial variability of absorption properties and simple forcing efficiency of light-absorbing water-soluble organic carbon (WSOC, SFEWSOC) by utilizing current and previous field-based measurements reported mostly from Asia along with a few observations from Europe, the USA, and the Amazon rainforest. The absorption coefficient of WSOC at 365 nm (babs-365) and the concentrations of carbonaceous species at Kanpur were about an order of magnitude higher during winter than in the monsoon season owing to differences in the boundary layer height, active sources and their strengths, and amount of wet precipitation. The WSOC aerosols during winter exhibited ∼1.6 times higher light absorption capacity than in the monsoon season at Kanpur site. The assessment of spatial variability of the imaginary component of the refractive index spectrum (kλ) across South Asia has revealed that it varies from ∼1 to 2 orders of magnitude and light absorption capacity of WSOC ranges from 3 to 21 W/g. The light absorption capacity of WSOC aerosols exhibited less spatial variability across East Asia (5 to 13 W/g) when compared to that in South Asia. The photochemical aging of WSOC aerosols, indicated by the enhancement in WSOC/OC ratio, was linked to degradation in their light absorption capacity, whereas the absorption Ångström exponent (AAE) remained unaffected. This study recommends the adoption of refined climate models where sampling regime specific absorption properties are calculated separately, such that these inputs can better constrain the model estimates of the global effects of BrC.
95. 题目: Design and fabrication of exfoliated Mg/Al layered double hydroxides on biochar support
期刊: Journal of Cleaner Production
作者: Yutao Peng, Yuqing Sun, Daniel C.W. Tsang, Aamir Hanif, Jin Shang, Zhengtao Shen, Deyi Hou, Yaoyu Zhou, Qing Chen, Yong Sik Ok
摘要: Tailored design and fabrication of biochar-based adsorbents with high porosity and well dispersion is a critical process for enhancing their environmental applications. To elucidate the material structure-performance relationship, this study synthesized and compared corn straw biochar-supported Mg/Al layered double hydroxides composites (LDHs-BCs) using conventional co-precipitation or aqueous miscible organic solvent treatment (AMOST) methods under various pyrolysis temperatures (350, 550, 750, and 950 °C) and metal loadings (5 and 15 wt.%). The comprehensive surface characterization demonstrated enlarged interlayer spacing, increased specific surface area, and smaller crystal size of LDHs as well as lowered intensities of O-containing functional groups in LDHs-BCs. These results suggested that, in comparison to conventional co-precipitation method, AMOST method can serve as a simple, cost-effective, and robust method to induce exfoliation, higher dispersion, and more stable attachment of LDHs on the biochar surface. The Langmuir adsorption isotherms further demonstrated that the AMOST-derived composites prepared at higher temperatures (i.e., 750 and 950 °C) and lower metal loading (i.e., 5 wt.%) exhibited superior contaminant removal capacities (280.7−286.2 mg PO43−/g and 92.5−94.7 mg Cu(II)/g at pH 5.0−6.0). The synergistic effect was attributed to coupled functionalization of LDHs and biochar under customized synthesis conditions. These results provide valuable insights into fabricating high-performance and environmentally friendly LDHs-BCs for green remediation and sustainable development.
96. 题目: Impacts of red mud on lignin depolymerization and humic substance formation mediated by laccase-producing bacterial community during composting
期刊: Journal of Hazardous Materials
作者: Zhiwei Jiang, Xintian Li, Mingqi Li, Qiuhui Zhu, Gen Li, Chaofan Ma, Qingyun Li, Jianzong Meng, Youyan Liu, Qunliang Li
摘要: The aim of this study was to investigate the impacts of red mud on lignin degradation, humic substance formation and laccase-producing bacterial community in composting to better improve composting performances. The results indicated that the organic matter contents of final compost products in the treatment group with red mud (T) decreased by 25.74%, which was more than the control group without red mud (CK) (12.09%). The final lignin degradation ratio and humic substance concentration of the T were 18.67% and 22.80% higher than that of the CK, respectively. The final C/N values of compost in the CK and T were 11.32 and 10.66, respectively, which were both less than 15, suggesting that compost reached maturity. Redundancy analysis showed that temperature was the main factors driving the variation of laccase-producing bacterial community. Pearson analysis suggested that Pseudomonas, Phenylobacterium, and Caulobacter were the most significantly correlated with lignin degradation and humification in the T.
97. 题目: Quenching of an Aniline Radical Cation by Dissolved Organic Matter and Phenols: A Laser Flash Photolysis Study
期刊: Environmental Science & Technology
作者: Frank Leresche, Lucie Ludvíková, Dominik Heger, Urs von Gunten, Silvio Canonica
摘要: Aromatic amines are relevant aquatic organic contaminants whose photochemical transformation is affected by dissolved organic matter (DOM). The goal of this study is to elucidate the underlying mechanism of the inhibitory effect of DOM on such reactions. The selected model aromatic amine, 4-(dimethylamino)benzonitrile (DMABN), was subjected to laser flash photolysis in the presence and absence of various model photosensitizers. The produced radical cation (DMABN•+) was observed to react with several phenols and different types of DOM on a time scale of ∼100 μs. The determined second-order rate constants for the quenching of DMABN•+ by phenols were in the range of (1.4–26) × 108 M–1 s–1 and increased with increasing electron donor character of the aromatic ring substituent. For DOM, quenching rate constants increased with the phenolic content of the DOM. These results indicate the reduction of DMABN•+ to re-form its parent compound as the basic reaction governing the inhibitory effect. In addition, the photosensitized oxidation of the sulfonamide antibiotic sulfadiazine (SDZ) was studied. The observed radical intermediate of SDZ was quenched by 4-methoxyphenol less effectively than DMABN•+, which was attributed to the lower reduction potential of the SDZ-derived radical compared to DMABN•+.
98. 题目: Distribution characteristics of low molecular weight organic acids in seawater of the Changjiang Estuary and its adjacent East China Sea: Implications for regional environmental conditions
期刊: Marine Pollution Bulletin
作者: Lina Lyu, Kejing Fang, Hong Jin, Gui-Peng Yang, Haorui Liang, Haibing Ding
摘要: In this study, components, concentrations, distribution characteristics and sources of low molecular weight organic acids (LMWOAs) in seawater of the Changjiang Estuary and its adjacent East China Sea were investigated in March 2015. Lactic, acetic and formic acids were identified with their concentration range of 0–16.7, 0–42.7 and 0–6.7 μmol·L−1, respectively. In the surface seawater, high concentrations of LMWOAs appeared in the sea area close to the estuary and along the coast. LMWOAs were important fractions of dissolved organic carbon and acetic acid was dominant component of LMWOAs. Riverine, terrestrial input, phytoplankton and sediment release were important sources for the LMWOAs, and human activities were considered as dominant sources for them in sampling period. The consistency of regions with high concentrations of LMWOAs, eutrophication, seasonal hypoxia and frequent red tide occurrence suggested LMWOAs as potential indicators for evaluating pollution status in coastal areas.
99. 题目: The effects of management practices on soil organic carbon stocks of oil palm plantations in Sumatra, Indonesia
期刊: Journal of Environmental Management
作者: Niharika Rahman, Ken E. Giller, Andreas de Neergaard, Jakob Magid, Gerrie van de Ven, Thilde Bech Bruun
摘要: The rapid increase in global production of and demand for palm oil has resulted in large-scale expansion of oil palm monoculture in the world's tropical regions, particularly in Indonesia. This expansion has led to the conversion of carbon-rich land-use types to oil palm plantations with a range of negative environmental impacts, including loss of carbon from aboveground biomass and soil. Sequestration of soil organic carbon (SOC) in existing oil palm plantations is an important strategy to limit carbon losses. The aim of this study was to investigate SOC stocks of oil palm plantations under different management systems. Soil samples were collected from three different management systems (best management practices (BMP), current management practices typical of large plantations (CMP) and smallholder management practices (SHMP)) in north Sumatra, Indonesia. Plantations were divided into four management zones that were sampled separately with four replicate profiles in the weeded circle, frond stack, harvesting path and interrow zones. All the soil samples were collected from five (0–5, 5–15, 15–30, 30–50 and 50–70 cm) soil depths. Soil samples were analysed for concentration of SOC, soil texture, soil bulk density and pH. Calculations of SOC stocks in the soils were undertaken according to the fixed-depth and equivalent soil mass approaches. Results showed that SOC stocks of plantations under BMP (68 t ha−1) were 31% and 18% higher than under CMP (57 t ha−1) and SHMP (46 t ha−1) respectively. In the BMP system, soils under the interrow zone that received enriched mulch and frond stack positions stored significantly more SOC than the harvesting path of the BMP system (77, 73 and 57 t ha−1 respectively). BMP also had a 33% higher fresh fruit bunch yield compared to the SHMP system. This study shows that residue incorporation or retention as a part of BMP could be an effective strategy for increasing SOC stocks of oil palm plantations and confirms that these management practices could improve yields from SHMP systems.
100. 题目: Spatial heterogeneity of biochar (segregation) in biochar-amended media: An overlooked phenomenon, and its impact on saturated hydraulic conductivity
期刊: Journal of Environmental Management
作者: Seyyed Ali Akbar Nakhli, Sydney Goy, Kalehiwot Nega Manahiloh, Paul Thomas Imhoff
摘要: While the use of biochar as a soil amendment is gaining popularity for environmental and agricultural purposes, spatial heterogeneity of biochar (segregation) in biochar-amended media and its underlying causes have been overlooked. In this study, for the first time particle segregation in biochar-amended media and its impact on the media's saturated hydraulic conductivity (Ksat) were investigated. Two uniformly graded media were amended with different sizes of a wood-based biochar under dry and wet conditions. While the intended biochar volume fraction (bf) was 17.5%, in dry-packed columns biochar was often segregated and the measured bf ranged from 7.5 ± 0.8 SE% (SE = standard error) to 23.6 ± 1.8 SE% across all spatial locations. If, however, 20% water (volume of water/bulk volume of packed media) was added to the mixtures during mixing, homogeneous packings were achieved. In dry-packing, segregation was governed by the difference in the physical properties of the media and the biochar: particle size, density, and shape. In wet-packing, segregation was prevented due to the inter-particle adhesion forces associated with water. Although X-ray computed tomography images showed that the presence of segregation altered particle distributions and pore morphologies, the Ksat for wet-packed and dry-packed columns were statistically identical. The results of this study suggest that laboratory methods for packing biochar-amended media should include moisturizing the mixture to inhibit particle segregation. Mixing under wet conditions is recommended for any type of soil and biochar and for any scale of application, in both the laboratory and field.