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24501. 题目: Unrecognized Contributions of Dissolved Organic Matter Inducing Photodamages to the Decay of Extracellular DNA in Waters
文章编号: N20012515
期刊: Environmental Science & Technology
作者: Xin Zhang, Jing Li, Mu-Cen Yao, Wen-Yuan Fan, Chuan-Wang Yang, Li Yuan, Guo-Ping Sheng
更新时间: 2020-01-25
摘要: Extracellular DNA (eDNA), which is derived from lysis or secretion of cells, is ubiquitous in various environments and crucial for gene dissemination, bacterial metabolism, biofilm integrity, and aquatic monitoring. However, these processes are largely influenced by damage to eDNA. Photodamage to eDNA, one of the most important types of DNA damage in natural waters, thus far remains unclear. In particular, the roles of the ubiquitous dissolved organic matter (DOM) in this process have yet to be determined. In this study, eDNA photodamage, including both deoxynucleoside damage and strand breaks, proved to be significantly influenced by DOM. DOM competed with eDNA for photons to inhibit the direct photodamage of eDNA. Nevertheless, DOM was photosensitized to produce reactive oxygen species (ROS) (i.e., hydroxyl radicals (·OH) and singlet oxygen (1O2)) to enhance the indirect photodamage of eDNA. The ·OH induced damage to four deoxynucleosides and strand breaks, and the 1O2 substantially enhanced deoxyguanosine damage. The presence of DOM changed the main photodamage products of deoxynucleosides, additional oxidation products induced by ROS formed besides pyrimidine dimers caused by UV. Results indicate that DOM-mediated indirect photodamage contributed significantly to eDNA photodamage in most water bodies. This study revealed the previously unrecognized crucial role of DOM in the decay of eDNA in waters.

24502. 题目: Paleo-environmental evidence of ecosystem change in Lake St. Clair region of Laurentian Great Lakes basin: contrasting responses to land-use change and invasive mussels
文章编号: N20012514
期刊: Journal of Paleolimnology
作者: Melissa M. Baustian, Yolanda M. Brooks, Mark Baskaran, Peter R. Leavitt, Bo Liu, Nathaniel Ostrom, R. Jan Stevenson, Joan B. Rose
更新时间: 2020-01-25
摘要: The Laurentian Great Lakes have been subject to substantial modification from diverse anthropogenic stressors, including nutrient enrichment, climate change, chemical and biological pollutants, and invasive species, yet little is known of the relative historical influence of these factors. Here we analyze diverse fossil metrics from vibracores at two sites, a bay area (Anchor Bay) and a tributary (Clinton River) in the Lake St. Clair ecosystem to determine the ecological responses from land-use practices and invasive mussel invasions. Sediment cores spanning over 100 years indicated that the expansion of non-native Dreissena polymorpha and Dreissena rostriformis (dreissenid mussels) into Anchor Bay site after the mid-1990s was associated with ~ 60 to 95% reduction in algal and cyanobacterial abundances and twofold increase in sedimentary organic matter (SOM) and bioavailable phosphorus. These increases in SOM and bioavailable phosphorus are relatively similar to increases inferred from the late nineteenth century when large portions of the watershed were cleared and drained for agriculture. In contrast, the Clinton River site experienced a continuous increase in the influx of nutrients, organic matter, and elevated sedimentary phototrophic pigments during the twentieth century and into the twenty-first century. Site comparisons suggest different mechanisms inducing changes in primary production varied, where Anchor Bay was mainly affected by the comparatively recent (since ca. mid-1990s) endogenous influence of invasive species, while the Clinton River site was primarily influenced by the input of exogenous anthropogenic nutrients over the past 100 years. These new findings illustrate that watershed management and policies within large lakes with multi-jurisdictional (national) Area of Concerns should consider site-specific regulatory mechanisms.

24503. 题目: Different carboxyl‐rich alicyclic molecules proxy compounds select distinct bacterioplankton for oxidation of dissolved organic matter in the mesopelagic Sargasso Sea
文章编号: N20012513
期刊: Limnology and Oceanography
作者: Shuting Liu, Rachel Parsons, Keri Opalk, Nicholas Baetge, Stephen Giovannoni, Luis M. Bolaños, Elizabeth B. Kujawinski, Krista Longnecker, YueHan Lu, Elisa Halewood, Craig A. Carlson
更新时间: 2020-01-25
摘要: Marine dissolved organic matter (DOM) varies in its recalcitrance to rapid microbial degradation. DOM of varying recalcitrance can be exported from the ocean surface to depth by subduction or convective mixing and oxidized over months to decades in deeper seawater. Carboxyl‐rich alicyclic molecules (CRAM) are characterized as a major component of recalcitrant DOM throughout the oceanic water column. The oxidation of CRAM‐like compounds may depend on specific bacterioplankton lineages with oxidative enzymes capable of catabolizing complex molecular structures like long‐chain aliphatics, cyclic alkanes, and carboxylic acids. To investigate the interaction between bacteria and CRAM‐like compounds, we conducted microbial remineralization experiments using several compounds rich in carboxyl groups and/or alicyclic rings, including deoxycholate, humic acid, lignin, and benzoic acid, as proxies for CRAM. Mesopelagic seawater (200 m) from the northwest Sargasso Sea was used as media and inoculum and incubated over 28 d. All amendments demonstrated significant DOC removal (2–11 μmol C L⁻¹) compared to controls. Bacterioplankton abundance increased significantly in the deoxycholate and benzoic acid treatments relative to controls, with fast‐growing Spongiibacteracea, Euryarcheaota, and slow‐growing SAR11 enriched in the deoxycholate treatment and fast‐growing Alteromonas, Euryarcheaota, and Thaumarcheaota enriched in the benzoic acid treatment. In contrast, bacterioplankton grew slower in the lignin and humic acid treatments, with oligotrophic SAR202 becoming significantly enriched in the lignin treatment. Our results indicate that the character of the CRAM proxy compounds resulted in distinct bacterioplankton removal rates of DOM and affected specific lineages of bacterioplankton capable of responding.

24504. 题目: Bacterioplankton metabolism of phytoplankton lysates across a cyclone‐anticyclone eddy dipole impacts the cycling of semi‐labile organic matter in the photic zone
文章编号: N20012512
期刊: Limnology and Oceanography
作者: Emma K. Wear, Craig A. Carlson, Matthew J. Church
更新时间: 2020-01-25
摘要: Mesoscale eddies, prominent physical processes in the stratified ocean gyres, affect community composition and metabolic rates of both phytoplankton and heterotrophic bacterioplankton (free‐living bacterial and archaeal) communities. We hypothesized that in situ differences in organic matter production would predispose bacterioplankton communities from cyclonic vs. anticyclonic eddies toward metabolic capabilities better suited to utilizing dissolved organic matter (DOM) from the phytoplankton groups commonly associated with each eddy polarity. To test this, we established dilution batch‐culture bioassay incubations along a cyclone to anticyclone spatial transect in the North Pacific Subtropical Gyre. Unamended incubations, to assess spatial variability in ambient DOM bioavailability, and incubations amended with lysates of phytoplankton cultures were established and community growth and metabolic responses were assessed. Over timescales of days, lysate type was more influential than incubation origin: Prochlorococcus lysate was rapidly remineralized, while Emiliania huxleyi lysate was efficiently incorporated into biomass and developed a unique community of copiotrophic bacteria. Over timescales of 1 week to 1 month, eddy effects were indirectly apparent in their potential to promote metabolic processes related to DOM production and consumption. Surface lysate incubations showed priming of ambient DOM, that is, the remineralization of DOM, which was otherwise not bioavailable, in the presence of labile substrates. Some incubations originating from the deep chlorophyll maximum demonstrated signatures of chemoautotrophy fueled by nitrification, coincident with eddy‐driven isopycnal uplift. We conclude that eddy polarity itself does not determine community‐level bacterioplankton metabolic capabilities; however, mesoscale processes may indirectly affect slower, semi‐labile organic matter processing in the oligotrophic ocean.

24505. 题目: Seasonality of Organic Matter Degradation regulates Nutrient and Metal Net Fluxes in a High Energy Sandy Beach
文章编号: N20012511
期刊: Journal of Geophysical Research: Biogeosciences
作者: Janis Ahrens, Melanie Beck, Hannah Marchant, Soeren Ahmerkamp, Bernhard Schnetger, Hans‐Jürgen Brumsack
更新时间: 2020-01-25
摘要: During seawater circulation in permeable intertidal sands, organic matter degradation alters the composition of percolating fluids and remineralization products discharge into surficial waters. Concurrently, coastal seawater nutrient and organic matter composition change seasonally due to variations in pelagic productivity. To assess seasonal changes in organic matter degradation in the intertidal zone of a high energy beach (Spiekeroog Island, southern North Sea, Germany), we analyzed shallow pore waters for major redox constituents (oxygen (O₂), manganese (Mn), iron (Fe)) and inorganic nitrogen species (nitrite (NO₂^‐), nitrate (NO₃^‐), ammonium (NH₄⁺)) in March, August, and October. Surface water samples from a local time series station were used to monitor seasonal changes in pelagic productivity. O₂ and NO₃^‐ were the dominating pore water constituents in March and October. Dissolved Mn, Fe, and NH₄⁺ were more widely distributed in August. Seasonal changes in seawater temperature as well as organic matter and nitrate supply by seawater were assumed to affect microbial rates and degradation pathways. Pore water and seawater variability led to seasonally changing constituent effluxes to surface waters. Mn, Fe, and NH₄⁺ effluxes are minimal in March and reached their maximum in August. Furthermore, the intertidal sands switched from a net dissolved inorganic nitrogen (DIN) sink in March to a net source in August. In conclusion, seasonal effects on intertidal pore water biogeochemistry affect constituent fluxes across the sediment‐water interface. The seasonality of the beach bioreactor must be considered when fluxes are extrapolated to annual timescales.

24506. 题目: Tillage intensity reduces the arbuscular mycorrhizal fungi attributes associated with Solanum lycopersicum, in the Tehuantepec Isthmus (Oaxaca), Mexico
文章编号: N20012510
期刊: Applied Soil Ecology
作者: Ángel Vivani de la Cruz-Ortiz, Jonás Álvarez-Lopeztello, Celerino Robles, Laura V. Hernández-Cuevas
更新时间: 2020-01-25
摘要: Understanding the responses of arbuscular mycorrhizal fungi (AMF) attributes and soil properties to tillage intensity is useful for the management of agroecosystems, especially in tropical lands, which are under intense pressures for human activities. This study aimed to examine the AMF attributes such as spore-based species richness, spore density, and root mycorrhizal colonization in systems with different tillage practices (intensive, traditional, and conservation). The soil of the study systems were sandy loam, moderately alkaline, and showed low levels of inorganic nitrogen and available phosphorus. Conservation tillage displayed the lowest pH and the highest inorganic nitrogen, soil organic carbon, and soil organic matter levels. Traditional tillage showed the lowest available phosphorus concentrations and the highest electric conductivity levels. Conservation tillage system showed the highest AMF spore-based species richness, spore density, and root mycorrhizal colonization; in contrast to intensive tillage that showed the lowest values. Spore density was not affected by the tillage intensity. Spore density and root mycorrhizal colonization appeared to increase with low available phosphorus levels. Spore density seemed to decrease as the levels of soil organic carbon and sand increased; by the contrary, root mycorrhizal colonization appeared to increase with high soil organic carbon levels, and decreased as the levels of inorganic nitrogen increased. This study highlights the conservation tillage as a useful management tool for maintaining the AMF attributes and soil properties.

24507. 题目: Selective carbon sources and salinities enhance enzymes and extracellular polymeric substances extrusion of Chlorella sp. for potential co-metabolism
文章编号: N20012509
期刊: Bioresource Technology
作者: Hoang Nhat Phong Vo, Huu Hao Ngo, Wenshan Guo, Yiwen Liu, Soon Woong Chang, Dinh Duc Nguyen, Xinbo Zhang, Heng Liang, Shan Xue
更新时间: 2020-01-25
摘要: This study investigated the extracellular polymeric substance (EPS) and enzyme extrusion of Chlorella sp. using seven carbon sources and two salinities for potential pollutant co-metabolism. Results indicated that the levels of biomass, EPS and enzymes of microalgae cultured with glucose and saccharose outcompeted other carbon sources. For pigment production, glycine received the highest chlorophyll and carotene, up to 10 mg/L. The EPS reached 30 mg/L, having doubled the amount of protein than carbohydrate. For superoxide dismutase and peroxidase enzymes, the highest concentrations were beyond 60 U/ml and 6 nmol/d.ml, respectively. This amount could be potentially used for degrading 40% ciprofloxacin of concentration 2000 µg/L. When increasing salinity from 0.1% to 3.5%, the concentrations of pigment, EPS and enzymes rose 3 to 30 times. These results highlighted that certain carbon sources and salinities could induce Chlorella sp. to produce EPS and enzymes for pollutant co-metabolism and also for revenue-raising potential.
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24508. 题目: Roles of biochar media and oxygen supply strategies in treatment performance, greenhouse gas emissions, and bacterial community features of subsurface-flow constructed wetlands
文章编号: N20012508
期刊: Bioresource Technology
作者: Bohua Ji, Jinquan Chen, Jian Mei, Junjun Chang, Xuan Li, Wei Jia, Ying Qu
更新时间: 2020-01-25
摘要: Biochar-based subsurface-flow constructed wetlands (CWs) with intermittent aeration (IA) or tidal flow (TF) oxygen supply strategies were established to treat domestic wastewater. The results showed that biochar achieved higher nutrient removal and lower greenhouse gas (GHG) emissions than ceramsite while supporting more diverse bacterial communities and higher abundances of functional taxa. Both IA and TF effectively enhanced nutrient removal, though the latter was more efficient and practical, and aeration conditions greatly influenced nutrient removal efficiency. GHG emissions were decreased by IA but were slightly increased by TF. Both oxygen supply methods significantly shaped the biofilm microbial communities and influenced biodiversity and richness, with observably higher proportions of potential nitrifiers and denitrifiers present in aerated CWs. Overall, biochar-based CWs operated with oxygen supply strategies provide superior treatment of decentralized wastewater.
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24509. 题目: Methane yield enhancement of mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste using algal biochar: Semi-continuous operation and microbial community analysis
文章编号: N20012507
期刊: Bioresource Technology
作者: Le Zhang, Fanghua Li, Agnès Kuroki, Kai-Chee Loh, Chi-Hwa Wang, Yanjun Dai, Yen Wah Tong
更新时间: 2020-01-25
摘要: The impact of algal biochar addition on mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste was investigated with a focus on semi-continuous operations and functional microbial communities. Under batch co-digestion, the highest co-digestion synergy was observed for a mixture of 25% food waste and 75% algal biomass. During semi-continuous co-digestion of 25% food waste-75% algal biomass mixture, biochar amended digesters exhibited a 12-54% increase in average methane yield (275.8-394.6 mL/gVS) compared to the controls. Elevated temperature induced narrow distributions of volatile fatty acids (VFAs) by inhibiting the production of branched VFAs. Genus Proteiniphilum was selectively enriched by 3.2 folds in mesophilic digesters with biochar amendment while genus Defluviitoga was selectively enriched in thermophilic digesters due to elevated temperature. Methanogenic communities were significantly different in mesophilic and thermophilic digesters. Biochar amendment contributed to shifts in the predominant methanogens leading to a more balanced state of two methanogenic pathways.
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24510. 题目: Optical properties of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) levels in constructed water treatment wetland systems in southern California, USA
文章编号: N20012506
期刊: Chemosphere
作者: Catherine D. Clark, Warren J. De Bruyn, Benjamin Brahm, Paige Aiona
更新时间: 2020-01-25
摘要: Many removal mechanisms in treatment wetlands involve absorption to organic matter. Optical properties and DOC levels of waters entering and exiting 4 treatment wetland systems in Orange County, Southern California, were measured to characterize the dissolved organic matter pool. Average DOC levels decreased between the inlets and outlets, except for Forge Street (FS), which increased. For 3 wetlands, absorption coefficients decreased between inlet and outlet; the exception was FS, which increased. Average spectral slopes for the inlets and outlets were similar. Average intensities of terrestrial humic peaks A and C from 3D EEM fluorescence spectra decreased between the inlets and outlets for most wetlands. No EEM protein peaks were observed. Average flu/abs ratios for inlets and outlets were similar (high point for FS inlet excluded), suggesting chromophoric dissolved organic matter (CDOM) of a similar composition was present. The average FI value for the inlets and outlets was ∼1.5, consistent with terrestrial sources of CDOM. Average BIX values for the inlets and outlets were ∼0.8, suggesting limited contributions from autochthonous production of CDOM. Dominant plant species in the wetlands were cattail and bulrush. Humic peaks A and C, along with protein peaks, were observed in plant leachates. Protein peaks rapidly degraded with solar simulator irradiation. Results indicate that most of the wetlands are a net sink for CDOM, possibly due to absorption to sediments. The FS wetland appears to have a source of non-CDOM optically active organic carbon, possibly from a pollutant.

24511. 题目: Substrate availability and soil microbes drive temperature sensitivity of soil organic carbon mineralization to warming along an elevation gradient in subtropical Asia
文章编号: N20012505
期刊: Geoderma
作者: Xiaojie Li, Jinsheng Xie, Qiufang Zhang, Maokui Lyu, Xiaoling Xiong, Xiaofei Liu, Tengchiu Lin, Yusheng Yang
更新时间: 2020-01-25
摘要: Subtropical forest soil exerts a large, but uncertain effect on terrestrial carbon (C) cycling. Global warming is anticipated to alter subtropical soil C cycling but currently, there is no consensus on how warming will affect soil C at different elevations. We conducted a short-term laboratory soil warming incubation experiment (ambient temperature +4 °C) along an elevational gradient in Wuyi Mountains of southeastern China to examine the response of soil organic carbon (SOC) mineralization to rising temperatures. Soil samples were collected from three elevations (630 m, 1450 m and 2130 m), and microbial community composition was determined using phospholipid fatty acids (PLFAs). The SOC mineralization increased with rising mean annual temperature (i.e., with decreasing elevation) and with experimental warming. Unlike most other similar experimental studies, we found that the temperature sensitivity (Q₁₀) of SOC mineralization to short-term experimental warming significantly decreased with increasing elevation. We also found that temperature sensitivity of SOC mineralization in response to warming depends on substrate availability, as indicated by the significant relationship between dissolved organic carbon (DOC) and Q₁₀ values. In addition, soil microbial biomass increased significantly with increasing elevations, but was not significantly affected by short-term experimental warming. Experimental warming reduced the abundance of total PLFAs, bacteria, fungi, and actinomycetes in the low-elevation soil. Experimental warming significantly changed soil microbial community composition at low elevation, with increases in the ratios of cyclopropyl to monoenoic precursor fatty acids (cy:pre), saturated to monounsaturated fatty acids (sat:mono), and isomers to trans-isomers fatty acids (i:a), all of which are stress indicators, indicating that warming treatment increased microbial respiration rather than microbial growth, because the microbial respiration per biomass increases under environmental stress. Microorganisms likely altered their membrane fatty acid components and mass in response to changes in available C. The differences in Q₁₀ associated with short-term warming and among elevations with long-term temperature differences indicate that the effect of warming on SOC mineralization may change through time and this should be taken into account when predicting SOC mineralization in response to continual rising temperatures.

24512. 题目: Fluorescent compounds retained by ultrafiltration membranes for water reuse
文章编号: N20012504
期刊: Journal of Membrane Science
作者: Anita Alexandra Sanchez, Natalie Mladenov, Joseph Wasswa
更新时间: 2020-01-25
摘要: Ultrafiltration (UF) membranes are increasingly being applied in water treatment and reuse processes because they provide effective removal of microorganisms, suspended solids, and high molecular weight compounds. However, membrane fouling necessitates backwashing and periodic chemical cleaning and, as a result, causes an increase in the amount of energy and overall cost for operation. Dissolved organic matter (DOM) has been identified as one of the major causes of biofilm formation and fouling during membrane ultrafiltration. Yet there is still much to be understood regarding how DOM interacts with biofilms, with some studies suggesting that labile DOM fractions may be preferentially removed by biogeochemical interactions with the biofilm. In this study, we evaluated the effects of biofilm formation on the retention of different organic compounds by measuring dissolved organic carbon, total dissolved nitrogen, DOM fluorescence peak intensities, and also performed parallel factor analysis (PARAFAC) modeling of fluorescent components to characterize the feed, permeate, and backwash during UF membrane fouling. We used a pilot scale, inside-out flow, UF membrane with a 0.03 μm pore size and different synthetic wastewater solutions as feed water. To evaluate the role of biofilms in preferential removal of DOM, unsterilized and sterilized synthetic wastewater solutions were run for several cycles. Results indicate that ultrafiltration for both solutions preferentially removed the biologically labile tryptophan-like components compared to the humic-like components. The similar percentage of removal of tryptophan-like components in both experiments suggest that the membrane biofilm on polyethersulfone membranes has little influence on the removal of biodegradable organic constituents. These findings also demonstrate that fluorescence spectroscopy can be a valuable tool to discriminate between different DOM fractions retained and passing through UF membrane filters.
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24513. 题目: Warming and increased precipitation indirectly affect the composition and turnover of labile-fraction soil organic matter by directly affecting vegetation and microorganisms
文章编号: N20012503
期刊: Science of The Total Environment
作者: Qiuyu Chen, Bin Niu, Yilun Hu, Tianxiang Luo, Gengxin Zhang
更新时间: 2020-01-25
摘要: Global warming accompanied by precipitation changes impacts soil carbon sequestration. A three-year field manipulation experiment with warming (+2 °C above ambient temperature) and increased precipitation (+15% and +30% above ambient precipitation) was conducted in an alpine grassland to investigate the response of soil organic matter (SOM) to future climate change on the Qinghai-Tibet Plateau (QTP). Labile-fraction SOM (LF-SOM) fingerprints were characterized by pyrolysis-gas chromatography/tandem-mass spectrometry (Py-GC–MS/MS), and organic compounds in LF-SOM were used as indicators to quantify the contributions of vegetation input and microbial degradation to LF-SOM transformation. Increased precipitation promoted LF-SOM accumulation, which were mainly due to the positive effect of increased precipitation on vegetation productivity. Plant-derived compounds in LF-SOM (including lignin, long-chain alkyl compounds, polysaccharides and phenols) were more sensitive to increasing soil moisture than microbial-derived (including short-chain alkyl compounds, N compounds and chitin) and aromatic-derived compounds (including aromatics and polyaromatics). In contrast, warming alone intensified the effect of drought on the alpine grassland, which had negative effects on both vegetation and microorganisms and reduced LF-SOM. Warming plus increased precipitation not only alleviated the water loss caused by warming but also increased soil temperature, which was more favorable for the growth of microorganisms. This was reflected in the increase in microbial-derived compounds in LF-SOM with increasing soil temperature, which contributed to LF-SOM degradation. Aromatic-derived compounds, as refractory compounds in soil, showed no significant response to either warming or increased precipitation treatments. Acidobacteria (approximately 25%) and Actinobacteria (approximately 20%), as the dominant soil bacterial communities in the alpine grassland, were significantly correlated with plant-derived compounds. At the same time, there were significant correlations between Proteobacteria and microbial-derived compounds, as well as between Firmicutes and aromatic-derived compounds (relative abundance). Under future climate change, microbial activity will increase as temperature increases, which will promote LF-SOM degradation only if precipitation also increases.
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24514. 题目: New insights into the harmful algae inhibition by Spartina alterniflora: Cellular physiology and metabolism of extracellular secretion
文章编号: N20012502
期刊: Science of The Total Environment
作者: Caicai Xu, Shitao Huang, Yuzhou Huang, Kokoette Effiong, Shumiao Yu, Jing Hu, Xi Xiao
更新时间: 2020-01-25
摘要: This study investigated the response of three toxic harmful algal blooms (HABs) species, Heterosigma akashiwo, Chattonella marina, and Alexandrium tamarense to coastal invasive plant, Spartina alterniflora. In this study, the growth of three HABs species were suppressed significantly by S. alterniflora extracts, showing a dose-response relationship. The raphidophyte H. akashiwo and C. marina exhibited higher inhibitory response with EC_50,7d decreased by 14% and 75% as compared to the dinoflagellate A. tamarense. C. marina was the most sensitive among the three species. S. alterniflora extracts disrupted algal cellular integrity and photosynthesis. Furthermore, the extracellular organic matters were detected by fluorescence excitation–emission matrix. Algal metabolites, protein-like substances (tyrosine-like peak and tryptophan-like peak) decreased as time prolonged and the humic-like substances (UVA marine humic-like peak) increased when algal cells were exposed to S. alterniflora extracts. These results provide new insights to the inhibition mechanism of S. alterniflora extracts on HABs species.
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24515. 题目: Molecular and microbial insights towards understanding the effects of hydrochar on methane emission from paddy soil
文章编号: N20012501
期刊: Science of The Total Environment
作者: Mengyuan Ji, Wenjing Sang, Daniel C.W. Tsang, Muhammad Usman, Shicheng Zhang, Gang Luo
更新时间: 2020-01-25
摘要: Directly returning rice straw to the paddy soil would significantly stimulate methane emission, and hydrochar has potential to be used as soil conditioner. However, the effects of hydrochar on the methane emission from paddy soil and the related mechanisms are still unclear. In the present study, straw-based hydrochar obtained at 200 °C (HC200), 250 °C (HC250) and 300 °C (HC300) and hydrochar after removal of bio-oil at these temperatures (CHC200, CHC250, and CHC300) were prepared and added to the paddy soil. The application of HC200, HC250 and HC300 resulted in the enhanced methane production compared to the control, showing 4.3, 1.6 and 1.5-fold higher methane production, respectively. It was related to the large amount of dissolved organic matter (DOM) released from hydrochar. Excitation-emission matrix fluorescence spectroscopy with parallel factor analysis (EEM-PARAFAC) showed that the hydrochar-derived DOM mainly included humic-like, phenolic and less aromatic structures, and with the increase of hydrothermal temperature, the content of humic-like substances and phenols increased, while biodegradable organics decreased. This was consistent with the maximum methane production by HC200. After incubation, there was no low-aromatic structures observed in the soil leachate, and the residual organics were mainly humus. The EEM-PARAFAC results were supported by compositional characterization of soil leachate by high-resolution mass spectrometry, and the refractory organics released from hydrochar was mainly lignins or (CRAM)-like structures in the range of H/C = 0.8–1.6 and O/C = 0.1–0.5. The organics dissolved from the washed hydrochar was significantly reduced, and some washed hydrochar (CHC250 and CHC300) even inhibited methane emission possibly due to their ability to adsorb organics. Microbial analysis further showed that the increased methane production resulted from hydrochar was associated with the enrichment of Janibacter, Anaeromyxobacter, Anaerolinea and Sporacetigenium. This present study provided a better understanding to the effect of hydrochar on methanogenesis in paddy soil.
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24516. 题目: Freezing-Induced Bromate Reduction by Dissolved Organic Matter and the Formation of Organobromine Compounds
文章编号: N20012425
期刊: Environmental Science & Technology
作者: Zhineng Hao, Fengqiong Shi, Dong Cao, Jing-Fu Liu, Guibin Jiang
更新时间: 2020-01-24
摘要: The freezing-induced acceleration of bromate reduction by humic substances (HS) contributes to HS bromination and the formation of organobromine compounds (OBCs). Herein, we report the enhanced reduction of bromate by dissolved organic matter and the formation of large amounts of OBCs in freezing solutions. After 48 h of freezing process, 78.1–100% of bromate was reduced by DOM at different initial concentrations of bromate and DOM in acidic solutions (pH 3 and 4). Bromide was one of the main reduction products, and it accounted for 30.9–47.8% of the total bromine content. Except for bromide, a large amount of OBCs formed by brominating DOM with reactive bromine species, like hypobromite, were detected. The conversion of bromate to OBCs, calculated as the total organobromine content to the initial bromate content, ranged from 28.2 to 52.5% and was mainly dependent on the bromate/DOM content. About 110–603 species of OBCs were detected by Fourier transform ion cyclotron resonance mass spectrometry, and they were primarily highly unsaturated and phenolic compounds. By analyzing the spectral variation before and after the freezing process, we found the disappearance of 900 compounds containing only C, H, and O with a low carbon oxidation state that was regarded as the main reductant of bromate. Our findings call for further investigation of the processes and the effects of bromate formation in aqueous environments.

24517. 题目: Preferential Sorption of Tannins at Aluminum Oxide Affects the Electron Exchange Capacities of Dissolved and Sorbed Humic Acid Fractions
文章编号: N20012424
期刊: Environmental Science & Technology
作者: Edisson Subdiaga, Mourad Harir, Silvia Orsetti, Norbert Hertkorn, Philippe Schmitt-Kopplin, Stefan B. Haderlein
更新时间: 2020-01-24
摘要: Natural organic matter and humic substances (HS) in soils and sediments participate in numerous biogeochemical processes. Sorption to redox-inert aluminum oxide (Al2O3) was recently found to affect the redox properties of HS both in sorbed and dissolved state. With this study, we aim to decipher the molecular basis for these observations by applying Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS) and mediated electrochemical analysis to Elliott soil, Pahokee peat, and Suwannee river humic acid (HA) samples before and after sorption to polar Al2O3 and a nonpolar sorbent (DAX-8 resin). The FT-ICRMS data provided evidence of preferential sorption of specific HA fractions, primarily tannin-like compounds, to Al2O3. These oxygen-rich compounds bear a high density of redox-active functional groups, and their adsorption leads to a depletion of electron exchange capacity in dissolved HAs and enrichment of HAs adsorbed at Al2O3. Sorption of HAs to DAX-8 was less selective and caused only slight changes in electron exchange capacities of dissolved and sorbed HA fractions. By combining FT-ICRMS and electrochemical approaches, our findings suggest that a selective sorption of oxygen-rich compounds in HA fractions to mineral oxides is a decisive factor for the different redox properties of dissolved and sorbed HA fractions.

24518. 题目: Reduction of chlordecone environmental availability by soil amendment of biochars and activated carbons from lignocellulosic biomass
文章编号: N20012423
期刊: Environmental Science and Pollution Research
作者: Ronald Ranguin, Corine Jean-Marius, Christelle Yacou, Sarra Gaspard, Cyril Feidt, Guido Rychen, Matthieu Delannoy
更新时间: 2020-01-24
摘要: Chlordecone (kepone or CLD) was formerly used in French West Indies as an insecticide. Despite its formal ban in 1993, high levels of this pesticide are still found in soils. As such, sequestering matrices like biochars or activated carbons (ACs) may successfully decrease the bioavailability of halogenated compounds like CLD when added to contaminated soils. The present study intends (i) to produce contrasted sequestering matrices in order to (ii) assess their respective efficiency to reduce CLD environmental availability. Hence, the work was designed following two experimental steps. The first one consisted at producing different sequestering media (biochars and ACs) via pyrolysis and distinct activation processes, using two lignocellulosic precursors (raw biomass): oak wood (Quercus ilex) and coconut shell (Cocos nucifera). The chemical activation was carried out with phosphoric acid while physical activation was done with carbon dioxide and steam. In the second step, the CLD environmental availability was assessed either in an OECD artificial soil or in an Antillean contaminated nitisol (i.e., 2.1^-1μg CLD per g of soil dry matter, DM), both amended with 5 wt% of biochar or 5 wt% of AC. These both steps aim to determine CLD environmental availability reduction efficiency of these media when added (i) to a standard soil material or (ii) to a soil representative of the Antillean CLD contamination context. Textural characteristics of the derived coconut and oak biochars and ACs were determined by nitrogen adsorption at 77 K. Mixed microporous and mesoporous textures consisting of high pore volume (ranging from 0.38 cm³.g⁻¹ to 2.00 cm³.g⁻¹) and specific (BET) surface areas from 299.9 m².g⁻¹ to 1285.1 m².g⁻¹ were obtained. Overall, soil amendment with biochars did not limit CLD environmental availability (environmental availability assay ISO/DIS 16751 Part B). When soil was amended with ACs, a significant reduction of the environmental availability in both artificial and natural soils was observed. AC soil amendment resulted in a reduced CLD transfer by at least 65% (P < 0.001) for all lignocellulosic matrices (excepted for coconut sample activated with steam, which displayed a 47% reduction). These features confirm that both pore structure and extent of porosity are of particular importance in the retention process of CLD in aged soil. Owing to its adsorptive properties, AC amendment of CLD-contaminated soils appears as a promising approach to reduce the pollutant transfer to fauna and biota.

24519. 题目: Enhancement of CO 2 adsorption on biochar sorbent modified by metal incorporation
文章编号: N20012422
期刊: Environmental Science and Pollution Research
作者: Nurul Azrin Zubbri, Abdul Rahman Mohamed, Naoto Kamiuchi, Maedeh Mohammadi
更新时间: 2020-01-24
摘要: This work is scrutinizing the development of metallized biochar as a low-cost bio-sorbent for low temperature CO₂ capture with high adsorption capacity. Accordingly, single-step pyrolysis process was carried out in order to synthesize biochar from rambutan peel (RP) at different temperatures. The biochar product was then subjected to wet impregnation with several magnesium salts including magnesium nitrate, magnesium sulphate, magnesium chloride and magnesium acetate which then subsequently heat-treated with N₂. The impregnation of magnesium into the biochar structure improved the CO₂ capture performance in the sequence of magnesium nitrate > magnesium sulphate > magnesium chloride > magnesium acetate. There is an enhancement in CO₂ adsorption capacity of metallized biochar (76.80 mg g⁻¹) compare with pristine biochar (68.74 mg g⁻¹). It can be justified by the synergetic influences of physicochemical characteristics. Gas selectivity study verified the high affinity of biochar for CO₂ capture compared with other gases such as air, methane, and nitrogen. This investigation also revealed a stable performance of the metallized biochar in 25 cycles of CO₂ adsorption and desorption. Avrami kinetic model accurately predicted the dynamic CO₂ adsorption performance for pristine and metallized biochar.

24520. 题目: Effect of Citric acid on extracellular polymeric substances disruption and cell lysis in the waste activated sludge by pH regulation
文章编号: N20012421
期刊: Bioresource Technology
作者: Xuewei Wu, Xiaoming Li, Qi Yang, Qiuxiang Xu, Ziletao Tao, Xiaoding Huang, You Wu, Lingjuan Tao, Zhoujie Pi, Zhuo Chen, Dongbo Wang
更新时间: 2020-01-24
摘要: This paper investigated the effects of citric acid (CA) on extracellular polymer destruction and cell lysis in sludge at different initial pH by measuring capillary suction time (CST), extracellular polymeric substances (EPS) and intracellular bound water. The results indicated that under CA concentration at 0.05 g / g suspended solids (SS) and initial pH 4, the CST value decreased from 175.5 s to 112.3 s, slime extracellular polymeric substances (S-EPS) and loosely bound EPS (LB-EPS) content respectively to increase from 4.92 to 41.43, 2.27 to 5.49 mg/g volatile suspended solids (Vss), while tightly bound EPS (TB-EPS) content to decrease from 12.35 to 5.01 mg/g (Vss), which suggested CA could disrupt outer EPS effectively. Intracellular bound water content decreased from 1.23 g / g to 0.41 g / g dry solid (DS). As a result, CA could release intracellular bound water effectively, thereby improving sludge dewatering degree.
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