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24521. 题目: Biochar is conducive to reduce thermal loss caused by mechanical turning during swine manure composting
文章编号: N19071912
期刊: Bioresource Technology
作者: Hongtao Liu
更新时间: 2019-07-19
摘要: The effects of biochar on temperature related performance and thermal loss during swine manure composting, when different mechanical turning frequencies were adopted, were investigated. Monitoring results showed that biochar addition significantly increased accumulated temperature and prolonged duration of thermophilic phase. More importantly, biochar addition remarkably reduced total thermal loss, which was a consensus between decreased heat exchange and incremental water vaporization heat, when there was one turning event. From heat output point of view, bichar decreased heat exchange and incremental water vaporization heat when one and two turning happened. In detail, biochar decreased the proportion of heat exchange from 66.2% to 61.6% and 67.2% to 62.7% respectively, and increased water vaporization heat from 22.1% to 32.9%, 17.3% to 23.9% respectively. Finally, biochar showed a potential to mitigate thermal loss caused by turning during swine composting.
24522. 题目: Ultra-efficient sorption of Cu2+ and Pb2+ ions by light biochar derived from Medulla tetrapanacis
文章编号: N19071911
期刊: Bioresource Technology
作者: Liping Zhang, Wenqi Li, Haisheng Cao, Die Hu, Xiang Chen, Ying Guan, Jun Tang, Hui Gao
更新时间: 2019-07-19
摘要: A novel mesoporous biochar (PBC) was facilely prepared from Medulla tetrapanacis. PBC exhibited high efficiency for the sorption of Cu2+ (458.72 mg/g) and Pb2+ (1031.23 mg/g) ions, and these values were higher than that of reported literatures. In the multi-metal system, the maximum sorption capacity for Cu2+, Pb2+, Cr3+, and Fe3+ were 430.88 mg/g, 701.63 mg/g, 696.67 mg/g, and 697.01 mg/g, respectively, and the removal efficiencies of those ions were more than 80 % at a metal ion concentration of 200 mg/L. Furthermore, the PBC was effective for the treatment of industrial effluent wastewater. The ash content (45.46%) of the PBC was higher than that of most other biochar derived from lignocellulosic biomass. Complexation, precipitation, π-π interactions, ion exchange, and physical sorption were the main sorption mechanisms. Overall, PBC is an inexpensive product, which is simply synthesized and an excellent adsorbent for heavy metal ion removal.
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24523. 题目: Influence of feedstocks and modification methods on biochar’s capacity to activate hydrogen peroxide for tetracycline removal
文章编号: N19071910
期刊: Bioresource Technology
作者: Yaoyao Wang, Haoran Dong, Long Li, Ran Tian, Jie Chen, Qin Ning, Bin Wang, Lin Tang, Guangming Zeng
更新时间: 2019-07-19
摘要: Three types of raw biochar (i.e. CBC, OBC, PBC produced from cornstalk, orange peel and peanut hull, respectively) and the modified ones (i.e., KMnO4-, KOH- and H3PO4-treatment) were employed to activate H2O2 for the removal of tetracycline (TC). The effects of pyrolysis temperatures, H2O2 concentration and initial pH were examined. TC removal by raw biochars w/o H2O2 was dependent on the feedstock and pyrolysis temperature of biochar, but the removal efficiency was still quite low under optimum conditions. The KMnO4-treatment significantly enhanced the adsorption of TC on all three biochars, but only enhanced the TC removal by CBC+H2O2. The KOH-treatment had insignificant effect on the adsorption of TC on biochar, but improved the performance of CBC/PBC+H2O2. The H3PO4-treatment had a negative impact on TC removal by biochar w/o H2O2. Overall, H2O2 could either enhance or decrease the TC removal by biochar, depending on biochar type, H2O2 concentration and solution pH.
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24524. 题目: Accelerated bio-methane production rate in thermophilic digestion of cardboard with appropriate biochar: Dose-response kinetic assays, hybrid synergistic mechanism, and microbial networks analysis
文章编号: N19071909
期刊: Bioresource Technology
作者: Dunjie Li, Liuying Song, Hongli Fang, Ping Li, Yue Teng, Yu-You Li, Rutao Liu, Qigui Niu
更新时间: 2019-07-19
摘要: The effect of biochar on the thermophilic digestion of mono-cardboard was investigated. Compared with control group (T0), the maximum rate of biomethane production was significantly improved after the addition of biochar, especially, it has been improved by 40.6% in T1 (0.77 g/gTS sludge) with the methane production of 89.28 mL/gVS. Also, the addition of biochar improved the efficiency of acidogenesis and acetogenesis. However, adverse effects were observed with the biomethane production decreased by 33.98% and the lag phase extended by 35 h in T5 (3.86 g/gTS sludge). Especially, the results showed that the adsorption of biochar played important roles in digestion. In addition, acetoclastic Methanosaeta which considered to be involved in interspecific electron transfer (IET) was enriched after biochar added and the highest diversity of acetogens was obtained in T1. Oppositely, microbial networks analysis showed that the excessive biochar may destroy the diversity of microorganism drastically.
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24525. 题目: Effect of particulate organic matter fractions on the distribution of heavy metals with aided phytostabilization at a zinc smelting waste slag site
文章编号: N19071908
期刊: Environmental Pollution
作者: Youfa Luo, Yonggui Wu, Jie Shu, Zhixue Wu
更新时间: 2019-07-19
摘要: Particulate organic matter (POM) significantly affects the distribution of heavy metals in contaminated soil. However, the effect of POM on the fate of heavy metals during in situ-aided phytostabilization of waste slag is unclear. The objective of this study was to investigate the distributions of heavy metals such as Cu, Pb, Zn, and Cd in the POM fractions at a zinc smelting waste slag site under in situ-aided phytostabilization after five years. The results showed that the litters and residues of four plants―Arundo donax, Broussonetia papyrifera, Cryptomeria fortunei, and Robinia pseudoacacia―decomposed to form different POM size fractions. The percentage of the 0.05–0.25 mm POM size fraction was the highest, followed by the >1 mm and 0.5–1 mm POM size fractions, and that of the 0.25–0.5 mm POM size fraction was the lowest. The masses of POM derived from the four plants were in the following order: C. fortunei > B. papyrifera > A. donax > R. pseudoacacia. The contents, enrichment coefficients, and mass loads of heavy metals such as Cu, Pb, Zn, and Cd in the POM increased with decreasing POM size, and those in the 0.05–0.25 mm POM size fraction were the highest. The mass load of heavy metals in the POM occurred in the following order: Cu > Cd > Zn > Pb. The surfaces of the POM with coarser and smaller size fractions were smoother and rougher, respectively, and the smaller POM size fractions had larger specific surface areas. The main functional groups in the different POM size fractions were –COOH, –OH, CO, CC, C–H, Si–O, and –CH3. The POM fractions played a significant role in determining the distribution of heavy metals in the revegetated waste slag. These findings have important implications for aided phytostabilization, which significantly influences the fate and speciation of heavy metals at the phytoremediation site.
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24526. 题目: A Global End-Member Approach to Derive aCDOM(440) from Near-Surface Optical Measurements
文章编号: N19071907
期刊: Biogeosciences
作者: Stanford B. Hooker, Atsushi Matsuoka, Raphael M. Kudela, Youhei Yamashita, Koji Suzuki, and Henry F. Houskeeper
更新时间: 2019-07-19
摘要: This study establishes an optical inversion scheme for deriving the absorption coefficient of colored (or chromophoric, depending on the literature) dissolved organic material (CDOM) at the 440 nm wavelength, which can be applied to global water masses with near-equal efficacy. The approach uses a ratio of diffuse attenuation coefficient spectral end members, i.e., a short and long wavelength pair. The global perspective is established by sampling "extremely" clear water plus a generalized extent in turbidity and optical properties that each span three decades of dynamic range. A unique data set was collected in oceanic, coastal, and inland waters (as shallow as 0.6 m) from the North Pacific Ocean, the Arctic Ocean, Hawaii, Japan, Puerto Rico, and the east and west coasts of the United States. The data were partitioned using subjective categorizations to define a validation quality subset of conservative water masses, i.e., the inflow and outflow of properties constrain the range in the gradient of a constituent, plus 15 subcategories of water masses that were not evolving conservatively. The dependence on subcategories was confirmed with an objective methodology based on cluster analysis techniques. The latter defined five distinct classes with validation quality data present in all classes, but which also decreased in percent composition as a function of increasing class number and optical complexity. Four different algorithms based on different validation quality end members were validated with accuracies of 1.–6.2 %, wherein pairs with the largest spectral span were most accurate. Although algorithm accuracy decreased with the inclusion of more subcategories containing non-conservative water masses, changes to the algorithm fit were small when a preponderance of subcategories were included. The high accuracy for all end-member algorithms was the result of data acquisition and data processing improvements, e.g., increased vertical sampling resolution to less than 1mm and a boundary constraint to mitigate wave focusing effects, respectively. An independent evaluation with a historical database confirmed the consistency of the algorithmic approach and its application to quality assurance, e.g., to flag data outside expected ranges, identify suspect spectra, and objectively determine the in-water extrapolation interval by converging agreement for all applicable end-member algorithms. The legacy data exhibit degraded performance (as 44 % uncertainty) due to a lack of high-quality near-surface observations, especially for clear waters wherein wave-focusing effects are problematic. The novel optical approach allows the in situ estimation of an in-water constituent in keeping with the accuracy obtained in the laboratory.
24527. 题目: Soil Organic Matter Composition in Coastal and Continental Date Palm Systems: Insights from Tunisian Oases
文章编号: N19071906
期刊: Pedosphere
作者: Rawan K. MLIH, Martina I. GOCKE, Roland BOL, Anne E. BERNS, Irabella FUHRMANN, Nadhem BRAHIM
更新时间: 2019-07-19
摘要: In Tunisia, the coastal Chenini oasis is characterized by a lush vegetation cover, whereas more inland continental oases (e.g., the Guettaya oasis) have a very scarce vegetation cover. For sustaining date palm production in these areas, organic fertilizers are applied, either spread on the soil surface (in Chenini) or buried under a sand layer (in Guettaya). We examined at a molecular level how these management techniques affect soil organic matter composition in oasis systems. A dominance of fresh plant input for Guettaya was indicated by solid-state 13C nuclear magnetic resonance spectroscopy signals, which was most pronounced in the uppermost soil close to palms. Evidence for more degraded organic matter was found in deeper soil near the palms, as well as in the soil distant from the palms. Amino sugar contents were low in the uppermost Guettaya soil near the palms. The overall microbial amino sugar residue contents were similar in range as those found in other dryland environments. With increasing distance from trees, the amino sugar contents declined in Guettaya, where the palms grow on bare soil, but this was not the case for Chenini, which has multi-layer vegetation cover under palms. In agreement with the results from previous dryland studies, the soil microbial community in both oasis systems was dominated by fungi in topsoil, and a shift toward bacteria-derived residues in subsurface soil. This might be due to higher variability of temperature and moisture in topsoil and/or lower degradability of fungal remains; however, further research is required to confirm this hypothesis.
24528. 题目: Responses of Soil Microbial Community Structure and Activity to Incorporation of Straws and Straw Biochars and Their Effects on Soil Respiration and Soil Organic Carbon Turnover
文章编号: N19071905
期刊: Pedosphere
作者: Xiaoping TIAN, Lei WANG, Yahong HOU, Han WANG, Yiu Fai TSANG, Jihua WU
更新时间: 2019-07-19
摘要: Like straw, biochar incorporation can influence soil microorganisms and enzyme activities and soil carbon (C) responses; however, few studies have compared the various effects of straw and biochar and the underlying mechanisms. An experiment was performed to study the changes in soil respiration (SR) and soil organic C (SOC) fluxes in response to the incorporation of three kinds of straw (reed, smooth cordgrass, and rice) and their pyrolyzed products (biochars) at Chongming Island, China. In addition, the microbial activity and community structure of some amended soils were also analyzed to clarify the mechanisms of these responses. The results showed that all biochar incorporation (BC) induced lower SR than the corresponding unpyrolyzed straw incorporation (ST), and the average SR in the soils following BC and ST during the experimental periods was 21.69 and 65.32 μmol CO2 m−2 s−1, respectively. Furthermore, the average SOC content was 16.97 g kg−1 following BC, which was higher than that (13.71 g kg−1) following ST, indicating that compared to ST, BC was a low-C strategy, even after accounting for the C loss during biochar production. Among the BC treatments, reed-BC induced the lowest SR (17.04 μmol CO2 m−2 s−1), whereas smooth cordgrass-BC induced the highest SR (27.02 μmol CO2 m−2 s−1). Furthermore, in contrast with ST, BC significantly increased the abundance of some bacteria with poorer mineralization or better humification ability, which led to lower SR. The lower easily oxidizable C (EOC) and higher total C contents of biochars induced lower SR and higher SOC in the soil following BC compared to that following ST. Among the BC treatments, the higher total nitrogen content of rice biochar led to significantly higher soil microbial biomass, and the lower EOC content of reed biochar led to lower soil microbial activity and SR.
24529. 题目: Response of fungal communities in different soils to biochar and chemical fertilizers under simulated rainfall conditions
文章编号: N19071904
期刊: Science of The Total Environment
作者: Mengyang Zhang, Muhammad Riaz, Lin Zhang, Hao Xia, Zeinab El-desouki, Cuncang Jiang
更新时间: 2019-07-19
摘要: Biochar is a good soil additive, which cannot only effectively store carbon, but also improve soil fertility and crop yield. However, the specific response of fungal communities to biochar and chemical fertilizers are still relatively lacking. In addition, most studies do not take into account rainfall factors when conducting culture experiments. In the case of simulated rainfall, we investigated the response of fungal communities in different soils to biochar and fertilizers in China and analyzed the correlation between chemical properties and different fungal species. The tested soils were yellow-brown soil, fluvo-aquic soil, lou soil and black soil, and the simulated daily rainfall was 25 mm. The results indicated that the application of biochar and chemical fertilizers had a greater impact on the alpha diversity of acidic soils (yellow-brown soil, fluvo-aquic soil), but less on alkaline soils (lou soil, black soil). The relative abundance of Ascomycetes was most affected by biochar and fertilizer in any soil. From the point of view of the fungal community, yellow-brown soil was more suitable for single application of biochar, because it not only improved the ability of the soil to degrade persistent organic matter but also inhibited the spread of soil pathogens. In black soil, the relative abundance of Fusarium was significantly reduced by the combined application of biochar and chemical fertilizers (FC), and the decline was much higher than several other bacteria. However, FC caused the greatest changes in the structure of all soil fungal communities. Moreover, there was a significant correlation between the content of available nutrients and composition of fungal community in fluvo-aquic soil. In summary, it can be explained that the effects of biochar and chemical fertilizers on soil fungi may vary depending on the soil type, so it is very urgent to conduct long-term research on different typical soils.
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24530. 题目: Linking chemical structure of dissolved organic carbon and microbial community composition with submergence-induced soil organic carbon mineralization
文章编号: N19071903
期刊: Science of The Total Environment
作者: Chao Ma, Xi Chen, Jingzhi Zhang, Yuanpeng Zhu, Yusef K. Kalkhajeh, Rushan Chai, Xinxin Ye, Hong-jian Gao, Wenying Chu, Jing-dong Mao, Michael L. Thompson
更新时间: 2019-07-19
摘要: Much research has been devoted to investigating how water-extractable organic carbon (DOC) concentration and microbial activity regulate soil organic carbon (SOC) mineralization when soils are saturated with water. However, the relationships of DOC chemical structure and microbial community composition with SOC mineralization, as well as the relative contributions of microbial decomposers and their substrates on the mineralization rate have rarely been examined. In a laboratory experiment, we incubated two typical cropland soils (an Entisol and a Mollisol) of China for 360 days under submerged and non-submerged conditions, and we evaluated the concentration and chemical structure of soil DOC, soil microbial metabolic potential and community composition by using total C/N analysis, solution-state 1H NMR, Biolog EcoPlates, and 16S rRNA amplicon sequencing, respectively. The results showed that submergence significantly increased DOC concentration (P < 0.01) and microbial activity (P < 0.001) and changed DOC chemical structure in the Entisol (P < 0.01). In the Mollisol, it significantly increased the rate (P < 0.01) and cumulative extent (P < 0.001) of SOC mineralization and DOC concentration (P < 0.01) as well as altering the composition of the microbial community (P < 0.001). Moreover, the SOC mineralization rate was better explained by microbial community composition (Entisol: SPC = −0.71, P < 0.001; Mollisol: SPC = 0.92, P < 0.001) than by DOC concentration (Entisol: SPC = 0.21, P > 0.05; Mollisol: SPC = 0.30, P < 0.05) or DOC chemical structure (Entisol: SPC = 0.12, P > 0.05; Mollisol: SPC = −0.45, P < 0.001). Our study revealed that the bacterial community composition had a close relationship to the rate of submergence-induced SOC mineralization in both soils, but only DOC concentration and chemical structure were effective predictors of mineralization rate in the low-pH Mollisol.
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24531. 题目: Impacts of typhoon-induced heavy rainfalls and resultant freshwater runoff on the partitioning of organic carbon oxidation and nutrient dynamics in the intertidal sediments of the Han River estuary, Yellow Sea
文章编号: N19071902
期刊: Science of The Total Environment
作者: Jin-Sook Mok, Sung-Han Kim, Jonguk Kim, Hyeyoun Cho, Sung-Uk An, Ayeon Choi, Bomina Kim, Cheolho Yoon, Bo Thamdrup, Jung-Ho Hyun
更新时间: 2019-07-19
摘要: Occurrence of typhoons accompanied by heavy precipitation has increased for the past 40 years in northeast Asia. To elucidate the impact of three consecutive typhoon-induced heavy rainfall events and resultant freshwater runoff on the partitioning of organic carbon (Corg) oxidation and nutrient dynamics, we investigated the geochemical constituents, the rate of anaerobic Corg oxidation, sulfate reduction (SR), iron reduction (FeR) and P speciation in the intertidal mud flat of the Han River estuary, Yellow Sea. Corg oxidation by SR and FeR and their metabolic products (∑CO2, NH4+, H2S, Fe2+) decreased significantly (P < 0.05) during and immediately after the heavy rainfall. Additional mesocosm experiments demonstrated that potential N2 production rates increased up to 2.4 times with increased nitrate concentrations during freshwater runoff. The results suggest that denitrification becomes a significant Corg oxidation pathway substituting for SR during high-nitrate freshwater runoff, which may remove substantial portion of the N introduced into the estuary. P speciation analysis further revealed that the concentrations of iron bound P decreased by 2.2 fold during the heavy rainfall compared to that measured before the rainfall. The results suggest that an excess supply of riverine Si keeps P from binding to Fe, thereby stimulating P release. Taking projections of enhanced rainfall events in the future into account, our results suggest that the intensified storm events and resultant riverine runoff induces a shift of Corg oxidation pathways in the sediments, which ultimately alters C-N-P-S-Fe dynamics and may deepen N-limiting conditions in coastal ecosystems of the Yellow Sea.
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24532. 题目: Spatial distribution of soil nematodes relates to soil organic matter and life strategy
文章编号: N19071901
期刊: Soil Biology and Biochemistry
作者: Casper W. Quist, Gerrit Gort, Paul Mooijman, Dick J. Brus, Sven van den Elsen, Olga Kostenko, Mariette Vervoort, Jaap Bakker, Wim H. van der Putten, Johannes Helder
更新时间: 2019-07-19
摘要: Soils are among the most biodiverse and densely inhabited environments on our planet. However, there is little understanding of spatial distribution patterns of belowground biota, and this hampers progress in understanding species interactions in belowground communities. We investigated the spatial distribution of nematodes, which are highly abundant and diverse metazoans in most soil ecosystems. To gain insight into nematode patchiness, we mapped distribution patterns in twelve apparently homogeneous agricultural fields (100 m × 100 m each) with equal representation of three soil textures (marine clay, river clay and sandy soil). Quantitative PCRs were used to measure the abundances of 48 distinct nematode taxa in ≈1,200 plots. Multivariate analysis showed that within this selection of sites, soil texture more strongly affected soil nematode communities than land management. Geostatistical analysis of nematode distributions revealed both taxon-specific and field-specific patchiness. The average geostatistical range (indicating patch diameter) of 48 nematode taxa in these fields was 36 m, and related to soil organic matter. Soil organic matter content affected the spatial variance (indicating within-field variation of densities) in a life-strategy dependent manner. The r-strategists (fast-growing bacterivores and fungivores) showed a positive correlation between organic matter content and spatial variance, whereas most K-strategists (slow-growing omnivores and carnivores) showed a negative correlation. Hence, the combination of two parameters, soil organic matter content and a general life-strategy characterisation, can be used to explain the spatial distribution of nematodes at field scale.
24533. 题目: Fate of Labile Organic Carbon in Paddy Soil Is Regulated by Microbial Ferric Iron Reduction
文章编号: N19071816
期刊: Environmental Science & Technology
作者: Jian-Xin Xu, Xiao-Ming Li, Guo-Xin Sun, Li Cui, Long-Jun Ding, Chen He, Liguan Li, Quan Shi, Barth F. Smets, Yong-Guan Zhu
更新时间: 2019-07-18
摘要: Global paddy soil is the primary source of methane, a potent greenhouse gas. It is therefore highly important to understand the carbon cycling in paddy soil. Microbial reduction of iron, which is widely found in paddy soil, is likely coupled with the oxidation of dissolved organic matter (DOM) and suppresses methanogenesis. However, little is known about the biotransformation of small molecular DOM accumulated under flooded conditions and the effect of iron reduction on the biotransformation pathway. Here, we carried out anaerobic incubation experiments using field-collected samples amended with ferrihydrite and different short-chain fatty acids. Our results showed that less than 20% of short-chain fatty acids were mineralized and released to the atmosphere. Using Fourier transform ion cyclotron resonance mass spectrometry, we further found that a large number of recalcitrant molecules were produced during microbial consumption of these short-chain fatty acids. Moreover, the biotransformation efficiency of short-chain fatty acids decreased with the increasing length of carbon chains. Ferrihydrite addition promoted microbial assimilation of short-chain fatty acids as well as enhanced the activation and biotransformation of indigenous stable carbon in the soil replenished with formate. This study demonstrates the significance of ferrihydrite in the biotransformation of labile DOM and promotes a more comprehensive understanding of the coupling of iron reduction and carbon cycling in paddy soils.
24534. 题目: Biochar accelerates the removal of tetracyclines and their intermediates by altering soil properties
文章编号: N19071815
期刊: Journal of Hazardous Materials
作者: Yan Yue, Congcong Shen, Yuan Ge
更新时间: 2019-07-18
摘要: Tetracyclines accumulation in soil environment potentially threatens agroecosystem safety. Interestingly, biochar could clean up organic pollutants, but to what extent biochar affects the removal of tetracyclines is unknown. To investigate it, five types of biochars derived from cow manure (CMB) and other four plant materials were respectively added into soils contaminated with a mixture of tetracycline, oxytetracycline, and chlortetracycline for 60-day incubation in the dark. Three parent tetracyclines and their corresponding intermediates (epitetracycline, anhydrotetracycline, epianhydrotetracycline, epioxytetracycline, epichlortetracycline, and demethylchlortetracycline) were respectively determined and named as TTCs, OTCs and CTCs. Obtained results showed biochar especially CMB could effectively remove the antibiotics (P < 0.05). Compared to control, the removal rate of TTCs, OTCs and CTCs respectively increased by up to 10.86%, 10.29% and 10.12% in CMB-added soil. The increased removal rate of the antibiotics after biochar addition was due to the increasing accessibilities for degrading microorganisms via the elevating electrical conductivity. Moreover, biochar addition might stimulate these microbial activities through the increase of C and N supplement. Our results indicate biochar accelerates the removal of tetracyclines and their intermediates by altering soil properties and thus increasing the antibiotics accessibilities, which provide insights into how biochar accelerates the removal for these antibiotics.
24535. 题目: Novel insights into integrated fermentation and nitrogen removal by free nitrous acid (FNA) serving as treatment method
文章编号: N19071814
期刊: Journal of Hazardous Materials
作者: Fangzhai Zhang, Yongzhen Peng, Baikun Li, Zhong Wang, Hao Jiang, Qiong Zhang
更新时间: 2019-07-18
摘要: Free nitrous acid (FNA) has only been studied as the pretreatment of waste activated sludge (WAS). Integrated fermentation and nitrogen removal using FNA as a primary means of treatment are seldom investigated. WAS fermentation was characterized under various FNA concentration. The production of COD, protein, and carbohydrate increased with FNA concentration (in the range of 0.197-1.97 mg/L) before the denitrification process. Volatile fatty acids (VFA) were only produced after complete denitrification. Potential FNA impact on fermentation step found FNA facilitated both solubilization and hydrolysis but inhibited acidification, acetogenesis, and methanogenesis processes. The types of fermentation were determined using threedimensional excitation-emission matrix (EEM) fluorescence spectroscopy. Protein-like substances and Tyrosine/Tryptophan were the most dominant dissolved organic matters (DOMs). The cell decay rate increased from 0.044 to 0.102/d based on the nonlinear fitting for the FNA concentration of 0.197-1.97 mg/L. The microbial biomass mortality reached 92.7% when the FNA in tight extracellular polymeric substances (T-EPS) exceeded 0.04 mg/L. In addition, the microbial diversity and microbial structure were substantially reduced by FNA during long-term operation, while the bacterial abundance associated with hydrolysis and acidification increased significantly.
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24536. 题目: Adsorption process of polar and nonpolar compounds in a nanopore model of humic substances
文章编号: N19071813
期刊: European Journal of Soil Science
作者: Daniel Tunega, Martin H. Gerzabek, Georg Haberhauer, Hans Lischka, Roland Solc, Adelia J. A. Aquino
更新时间: 2019-07-18
摘要: Humic substances (HSs) as a major part of soil organic matter are complex combinations of natural organic matter, which are ubiquitous in the environment, and occur predominantly in soils, residues, and natural water. They play a crucial role in the fate and behaviour of contaminants in the environment. In this work, a HS nanopore model was based on a structural motif containing polar and nonpolar domains. The polar domain was represented by the carboxyl groups that predominate in the composition of HSs, while the nonpolar domain was constructed by aliphatic chains. The effect of hydrophobic/hydrophilic interactions on sorption in HSs was analyzed by the inclusion of the nonpolar polycyclic aromatic hydrocarbon naphthalene and the polar herbicide 2‐methyl‐4‐chlorophenoxyacetic acid (MCPA) into the nanopore. Water cluster was also included to allow the formation of the water molecular bridges (WaMB), which stabilized the whole system. Thermodynamic potential‐of‐mean‐force (PMF) calculations by means of classical molecular dynamics simulations were performed to investigate the effect of polar and nonpolar domains in the adsorption mechanism. The polar MCPA molecule was stabilized at the hydrophilic water‐HS interface, whereas nonpolar naphthalene was stabilized inside of the hydrophobic nanovoid of the HS nanopore model. The obtained results demonstrated that the adsorption strength of HSs regarding polar and nonpolar species is similar, but the adsorption mechanisms differ.
24537. 题目: Effects of maize straw‐derived biochar application on soil temperature, water conditions and growth of winter wheat
文章编号: N19071812
期刊: European Journal of Soil Science
作者: Qiuyan Yan, Fei Dong, Junhui Li, Zengqiang Duan, Feng Yang, Xun Li, Jinxiu Lu, Feng Li
更新时间: 2019-07-18
摘要: Biochar application to soil has been widely accepted as an approach to enhance soil carbon sequestration, promote nutrient use efficiency and improve crop yields. Maize straw‐derived biochar application is also a novel practice for the sustainable use of straw waste. However, it remains unclear whether biochar modifies soil temperature, thereby influencing winter wheat growth. Field experiments were conducted for two years to answer this question. Maize straw‐derived biochar was applied at rates of 0 (B0), 20 (B20), 40 (B40) and 60 (B60) t ha‐1 in the field plots. Biochar application increased the soil temperature compared to the unamended control plot for all growth stages. The highest soil temperatures occurred at 40‐cm depth in the B40 treatment and 20‐cm depth in the B60 treatment. Biochar application also enhanced the soil water content of the winter wheat fields during the growing seasons, with a maximum effect achieved at a rate of biochar application of 40 t ha‐1. However, water content did not increase with increasing rate of application. Biochar application decreased the soil bulk density, and this effect was enhanced with increasing rates of biochar application. The largest grain yield was obtained in the B40 treatment, resulting from an increase in aboveground biomass and effective spike number. Our study suggests that biochar application potentially improves the grain yield of winter wheat from the increased soil temperature. This conclusion needs to be confirmed by a long‐term study on biochar application.
24538. 题目: Anthropogenic N deposition alters soil organic matter biochemistry and microbial communities on decaying fine roots
文章编号: N19071811
期刊: Global Change Biology
作者: William A. Argiroff, Donald R. Zak, Rima A. Upchurch, Sydney O. Salley, A. Stuart Grandy
更新时间: 2019-07-18
摘要: Fine root litter is a primary source of soil organic matter (SOM), which is a globally important pool of C that is responsive to climate change. We previously established that ~20 years of experimental nitrogen (N) deposition has slowed fine root decay and increased the storage of soil carbon (C; +18%) across a widespread northern hardwood forest ecosystem. However, the microbial mechanisms that have directly slowed fine root decay are unknown. Here, we show that experimental N deposition has decreased the relative abundance of Agaricales fungi (‐31%) and increased that of partially ligninolytic Actinobacteria (+24%) on decaying fine roots. Moreover, experimental N deposition has increased the relative abundance of lignin‐derived compounds residing in SOM (+53%), and this biochemical response is significantly related to shifts in both fungal and bacterial community composition. Specifically, the accumulation of lignin‐derived compounds in SOM is negatively related to the relative abundance of ligninolytic Mycena and Kuehneromyces fungi, and positively related to Microbacteriaceae. Our findings suggest that by altering the composition of microbial communities on decaying fine roots such that their capacity for lignin degradation is reduced, experimental N deposition has slowed fine root litter decay, and increased the contribution of lignin‐derived compounds from fine roots to SOM. The microbial responses we observed may explain widespread findings that anthropogenic N deposition increases soil C storage in terrestrial ecosystems. More broadly, our findings directly link composition to function in soil microbial communities, and implicate compositional shifts in mediating biogeochemical processes of global significance.
24539. 题目: Nitrate addition stimulates microbial decomposition of organic matter in salt marsh sediments
文章编号: N19071810
期刊: Global Change Biology
作者: Ashley N. Bulseco, Anne E. Giblin, Jane Tucker, Anna E. Murphy, Jonathan Sanderman, Kenly Hiller‐Bittrolff, Jennifer L. Bowen
更新时间: 2019-07-18
摘要: Salt marshes sequester carbon at rates more than an order of magnitude greater than their terrestrial counterparts, helping to mitigate climate change. As nitrogen loading to coastal waters continues, primarily in the form of nitrate, it is unclear what effect it will have on carbon storage capacity of these highly productive systems. This uncertainty is largely driven by the dual role nitrate can play in biological processes, where it can serve as a nutrient‐stimulating primary production or a thermodynamically favorable electron acceptor fueling heterotrophic metabolism. Here, we used a controlled flow‐through reactor experiment to test the role of nitrate as an electron acceptor, and its effect on organic matter decomposition and the associated microbial community in salt marsh sediments. Organic matter decomposition significantly increased in response to nitrate, even at sediment depths typically considered resistant to decomposition. The use of isotope tracers suggests that this pattern was largely driven by stimulated denitrification. Nitrate addition also significantly altered the microbial community and decreased alpha diversity, selecting for taxa belonging to groups known to reduce nitrate and oxidize more complex forms of organic matter. Fourier Transform‐Infrared Spectroscopy further supported these results, suggesting that nitrate facilitated decomposition of complex organic matter compounds into more bioavailable forms. Taken together, these results suggest the existence of organic matter pools that only become accessible with nitrate and would otherwise remain stabilized in the sediment. The existence of such pools could have important implications for carbon storage, since greater decomposition rates as N loading increases may result in less overall burial of organic‐rich sediment. Given the extent of nitrogen loading along our coastlines, it is imperative that we better understand the resilience of salt marsh systems to nutrient enrichment, especially if we hope to rely on salt marshes, and other blue carbon systems, for long‐term carbon storage.
24540. 题目: Demethylated hopanoids in ‘Ca. Methylomirabilis oxyfera’ as biomarkers for environmental nitrite-dependent methane oxidation
文章编号: N19071809
期刊: Organic Geochemistry
作者: Nadine T. Smit, Darci Rush, Diana X. Sahonero-Canavesi, Monique Verweij, Olivia Rasigraf, Simon Guerrero Cruz, Mike S. M. Jetten, Jaap S. Sinninghe Damsté, Stefan Schouten
更新时间: 2019-07-18
摘要: Hopanoids are lipids that are widespread in the bacterial domain and are well established molecular biomarkers in modern and paleo environments. In particular, the occurrence of 13C-depleted 3-methylated hopanoids are characteristic of aerobic bacteria involved in methane oxidation. Previously the intra-aerobic methanotroph ‘Candidatus Methylomirabilis oxyfera’ (‘Ca. M. oxyfera’), which performs nitrite-dependent methane oxidation in anoxic environments, has been shown to synthesize bacteriohopanepolyols (BHPs) and their 3-methylated counterparts. However, since ‘Ca. M. oxyfera’ does not utilize methane as a carbon source, its biomass and lipids do not show the characteristic 13C-depletion. Therefore, the detection of ‘Ca. M. oxyfera’ in various environments is challenging, and still underexplored. Here, we re-investigated the hopanoid content of ‘Ca. M. oxyfera’ bacteria using enrichment cultures. We found the GC-amenable hopanoids of ‘Ca. M. oxyfera’ to be dominated by four demethylated hopanoids of which only one, 22,29,30-trisnorhopan-21-one, had been identified previously. The three novel hopanoids were tentatively identified as 22,29,30-trisnorhopan-21-ol, 3-methyl-22,29,30-trisnorhopan-21-one and 3-methyl-22,29,30-trisnorhopan-21-ol. These unique demethylated hopanoids are most likely biosynthesized directly by ‘Ca. M. oxyfera’ bacteria. Bioinformatical analysis of the ‘Ca. M. oxyfera’ genome revealed potential candidate genes responsible for the demethylation of hopanoids. For the sensitive detection of the four trisnorhopanoid biomarkers in environmental samples, a multiple reaction monitoring (MRM) method was developed and used to successfully detect the trisnorhopanoids in a peatland where the presence of ‘Ca. M. oxyfera’ had been confirmed previously by DNA-based analyses. These new biomarkers may be a novel tool to trace nitrite-dependent methane oxidation in various (past) environments.