14581. 题目: Authigenic metastable iron sulfide minerals preserve microbial organic carbon in anoxic environments
期刊: Chemical Geology
作者: Aude Picard, Amy Gartman, Julie Cosmidis, Martin Obst, Charles Vidoudez, David R. Clarke, Peter R. Girguis
摘要: The burial of organic carbon (OC) in sedimentary environments promotes long-term carbon sequestration, which allows the release of oxygen in the atmosphere. Organo-mineral interactions that form between terrigenous minerals and OC during transport to and deposition on the seabed enhance OC preservation. Here, we propose an authigenic mechanism for the coupled preservation of labile OC and metastable iron sulfide minerals under anoxic conditions. Sulfate-reducing microorganisms (SRM) are ubiquitous in anoxic environments and produce the majority of free sulfide in marine sediments, leading to the formation of iron sulfide minerals in situ. Using high spatial resolution microscopy, spectroscopy and spectro-microscopy, we show that iron sulfide biominerals precipitated in the presence of SRM incorporate and adsorb organic molecules, leading to the formation of stable organo-mineral aggregates that could persist for years in anoxic environments. OC/iron sulfide assemblages consist of the metastable iron sulfide mineral phases mackinawite and/or greigite, along with labile organic compounds derived from microbial biomass or from organic molecules released extracellularly by SRM. Together these results underscore the role that a major group of anoxic microbes play in OC preservation and illustrate the value of the resulting authigenic metastable iron sulfide minerals mackinawite and greigite in protecting labile organic molecules from degradation over time.
14582. 题目: Graphitic biochar catalysts from anaerobic digestion sludge for nonradical degradation of micropollutants and disinfection
期刊: Chemical Engineering Journal
作者: Yi-di Chen, Xiaoguang Duan, Chaofan Zhang, Shaobin Wang, Nan-qi Ren, Shih-Hsin Ho
摘要: The peroxydisulfate(PDS) -based advanced oxidation processes (AOPs) is a promising technology for wastewater treatment and the efficiency primarily depends on the high-performance catalysts. Therefore, it is necessary to develop a green and low-cost biomaterial for PDS activation to drive such a process. In this study, biochar catalysts were produced via pyrolysis of anaerobic digestion sludge (ADS) as effective PDS activators. The biochar derived from ADS (ADSBC) yielded large specific surface areas, a high degree of graphitization and good conductivity, which can be used for effectively oxidizing various pollutants including dyes, estrogens and sulfonamides with PDS in broad pH and temperature ranges. It is showed that PDS activated by ADSBC 1000 can completely remove sulfathiazole in 90 min much higher than that of ADSBC 400 (20.25%). Moreover, the biochar produced under high pyrolysis temperature shows great stability and low biotoxicity due to the limited metals leaching and eliminated persistent free radicals as well as dissolved organic matter. The mechanism of the ADSBCs/PDS system was critically discussed via selectively radical screening tests, solvent exchange (H2O to D2O), selectivity to pollutants and electrochemical analysis. These results revealed that the organics were decomposed by a nonradical pathway via electron transfer rather than relying on free radicals or singlet oxygen. More importantly, the biochar-based nonradical oxidation system can leveraged for inactivation of Escherichia coli (E. coli) and diverse bacteria in both simulated and real wastewater. Therefore, this work not only provides an approach to reuse the sludge residue to prepare graphitic biochar catalysts as PDS activators for decontamination of emerging micropollutants, but also expands the practical application of advanced carbocatalysis for bacteria inactivation by nonradical oxidation in real wastewater.
14583. 题目: Degradation of imidacloprid by UV-activated persulfate and peroxymonosulfate processes: Kinetics, impact of key factors and degradation pathway
期刊: Ecotoxicology and Environmental Safety
作者: Qiongfang Wang, Pinhua Rao, Guanghui Li, Lei Dong, Xin Zhang, Yisheng Shao, Naiyun Gao, Wenhai Chu, Bin Xu, Na An, Jing Deng
摘要: UV-activated persulfate (UV/PS) and peroxymonosulfate (UV/PMS) processes as alternative methods for removal of imidacloprid (IMP) were conducted for the first time. The reaction rate constants between IMP and the sulfate or hydroxyl radical were calculated as 109 or 101011, respectively. The degradation of IMP was greatly improved by UV/PS and UV/PMS compared with only UV or oxidant. At any given dosage, UV/PS achieved higher IMP removal rate than UV/PMS. The pH range affecting the degradation in the UV/PS and UV/PMS systems were different in the ranges of 6–8 and 9 to 10. SO42, F− and NO3 had no obvious effect on the degradation in the UV/PS and UV/PMS systems. CO32 and PO43 inhibited the degradation of IMP in the UV/PS system, while they enhanced the degradation in the UV/PMS system. Algae organic matters (AOM) were used to consider the impact of the degradation of IMP for the first time. The removal of IMP were restrained by both AOM and natural organic matters. The higher removal rate of IMP demonstrated that both UV/PS and UV/PMS were suitable for treating the water containing IMP, while UV/PS was cost-effective than UV/PMS based on the total cost calculation. Finally, the degradation pathways of IMP were proposed.
14584. 题目: Biogeochemical behavior of metals along two permeable reactive barriers in a mining‐affected wetland
期刊: Journal of Geophysical Research: Biogeosciences
作者: Konstantin Gunten, Brendan Bishop, Luyu Zhang, Karlis Muehlenbachs, Md. Samrat Alam, Kurt O. Konhauser, Daniel S. Alessi
摘要: The biogeochemistry of two alkaline permeable reactive barriers (PRBs) installed for remediation in a mining‐affected wetland was investigated in order to assess the importance of colloidal particles on metal removal processes in such systems. At the time of investigation, both PRBs were effective in removing U, Cu, and Zn (>95%) from groundwater but were slightly less efficient for Ni and Co (<90%). Previously installed groundwater wells allowed an in‐depth analysis of groundwater passing through the first PRB. Here, in an alkaline environment (pH 6.0‐9.7), 11‐14% of Ni, 36‐37% of Co, 77‐81% of Cu, 14‐17% of U, and 10‐19% of Fe were associated with organic matter and inorganic colloids, while upgradient in the more acidic environments (pH <6.0), ionic species and complexes (e.g., Co2+, Ni2+, Cu2+, UO2H3SiO4 +) dominated. Copper and U preferentially bound to larger colloidal fractions (>1 kDa), which might have promoted their sequestration. Uranium removal was likely further enhanced by U (VI) reduction in the alkaline and oxygen‐depleted conditions of the PRBs. The less efficient removal of Ni and Co, being target metals for remediation, was explained by a combination of their high solubility, unfavorable redox and pH conditions created by the alkaline PRBs, and their limited association with colloidal particles. These considerations that are critical in the design of future PRBs for the remediation of similar systems.
14585. 题目: Peatland contribution to stream organic carbon exports from a montane watershed
期刊: Journal of Geophysical Research: Biogeosciences
作者: T. Rosset, L. Gandois, G. Le Roux, R. Teisserenc, P. Durantez Jimenez, T. Camboulive, S. Binet
摘要: Mountains contain many small and fragmented peatlands within watersheds. As they are difficult to monitor, their role in the water and carbon cycle is often disregarded. This study aims to assess the stream organic carbon exports from a montane peatland and characterizes its contribution to the water chemistry in a headstream watershed. High frequency in situ monitoring of turbidity and fDOM were used to quantify respectively particulate (POC) and dissolved (DOC) organic carbon exports at the inlet and outlet of a peatland over three years in a French Pyrenean watershed (1343 m.a.s.l.). The DOC and POC signals are both highly dynamic, characterized by numerous short peaks lasting from a few hours to a few days. Forty‐six percent of the exports occurred during 9% of the time corresponding to the highest flows monitored at the outlet. Despite its small area (3%) within the watershed, the peatland contributes at least 63% of the DOC export at the outlet. The specific DOC flux ranges from 16.1±0.4 to 34.6±1.5 g.m2. yr‐1. POC contributes 17% of the total stream organic carbon exports from the watershed. As the frequency of extreme climatic events is expected to increase in the context of climate change, further studies should be conducted to understand the evolution of under‐estimated mountainous peatland carbon fluxes and their implication in the carbon cycle of headwaters.
14586. 题目: Reduction‐oxidation potential and dissolved organic matter composition in northern peat soil: interactive controls of water table position and plant functional groups
期刊: Journal of Geophysical Research: Biogeosciences
作者: E.S. Kane, T.J. Veverica, M.M. Tfaily, E.A. Lilleskov, K.M. Meingast, R.K. Kolka, A.L. Daniels, R.A. Chimner
摘要: Globally important carbon (C) stores in northern peatlands are vulnerable to oxidation in a changing climate. A growing body of literature draws attention to the importance of dissolved organic matter (DOM) in governing anaerobic metabolism in organic soil, but exactly how the reduction‐oxidation (redox) activities of DOM, and particularly the phenolic fraction, are likely to change in an altered climate remain unclear. We used large mesocosms in the PEATcosm experiment to assess changes in peatland DOM and redox potential in response to experimental manipulations of water table (WT) position and plant functional groups (PFGs). WT position and PFGs interacted in their effects on redox potential and quantity and quality of DOM. Phenolics were generally of higher molecular weight and more oxidized with sedges in lowered water tables. Altered DOM character included changes in dissolved nitrogen (N), with higher N:[phenolics] with higher E4:E6 (absorbance ratio λ=465:665) DOM in the lowered WT and sedge PFG treatments. Conversely, biomolecular assignments to amino‐sugars were largely absent from low WT treatments. Low WT resulted in the creation of unique N compounds which were more condensed (lower H:C), that changed with depth and PFG. The accumulation of oxidized compounds with low WT and in sedge rhizospheres could be very important pools of electron acceptors beneath the water table, and their mechanisms of formation are discussed. This work suggests the effects of changes in vegetation communities can be as great as WT position in directly and interactively mediating peat redox environment and the redox‐activity of DOM.
14587. 题目: Effects of biochar amendment on bacterial and fungal communities in the reclaimed soil from a mining subsidence area
期刊: Environmental Science and Pollution Research
作者: Yuan Liu, Jirong Zhu, Wenhui Gao, Zonghao Guo, Chen Xue, Jiayin Pang, Liangzuo Shu
摘要: Biochar amendment of soil is well known to improve soil fertility and microbial function. However, little is known about the effect of biochar addition to reclaimed soil in coal mining subsidence area on microbial community. A plant soil cultivation experiment was conducted with wheat grown and four treatments were included: P and K fertilizer (CK); NPK inorganic fertilizer (NPK); NPK inorganic fertilizer and straw (NPKS); and NPK inorganic fertilizer and biochar (NPKB). The results indicated that biochar amendment significantly increased the concentrations of NH4+-N, total N, and available P and K compared with the NPK. Biochar addition also significantly increased the grain yield and total biomass of wheat. Furthermore, biochar amendment treatment increased the absolute abundance and altered the community structure of soil bacteria and fungi in the reclaimed soil. Illumina MiSeq sequencing showed that the addition of biochar increased α-diversity of bacteria and relative abundances of Proteobacteria, Actinobacteria, and Bacteroidetes, whereas the relative abundance of Firmicutes were decreased by 61%. However, biochar addition did not change the relative abundance of dominant fungal phyla. Redundancy analysis (RDA) suggested that total N, available P, and K contents were the key factors correlated with changes in microbial community structure. Overall, our results suggest that biochar amendment in reclaimed soil in coal mine subsidence area could increase wheat yield and abundance and alter microbial community compositions.
14588. 题目: Anaerobically digested blackwater treatment by simultaneous denitrification and anammox processes: Feeding loading affects reactor performance and microbial community succession
作者: Yun Zhou, Bing Guo, Lei Zhang, Xin Zou, Sen Yang, Huixin Zhang, Siqing Xia, Yang Liu
摘要: Source diverted blackwater collected from toilets can be anaerobically digested to recover energy. The anaerobically digested blackwater (ADB) contains high levels of ammonium and low carbon to nitrogen (C/N) ratio. In the present study, ADB was treated by a two-stage nitritation-denitrification/anammox process in an integrated fixed film activated sludge-continuous flow reactor (IFAS-CFR). NH4+-N, NO2--N, total nitrogen (TN), and chemical oxygen demand (COD) removal efficiencies were 80%, 82%, 76%, and 78%, respectively. Anaerobic ammonium oxidation (anammox) and denitrification contributed to 44–48%, and 52–56% of total nitrogen removal, respectively. Both of the protein- and humic acid-like matters were removed during the process. An increase in feed load promoted the sustained growth of anammox bacteria—Candidatus Brocadia in the biofilm, as well as an increase of denitrifiers (Pseudomonas, Thermotonus, Phodanobacter, Caulobacter) in both biofilm and suspended biomass, which remained higher in the suspended biomass than in biofilm. Overall, biofilm had higher nitrogen removal efficiency than suspended biomass, while suspended biomass had a higher COD removal efficiency than biofilm.
14589. 题目: Characterization of sulfate-reducing bacteria anaerobic sludge granulation enhanced by chitosan
期刊: Journal of Environmental Management
作者: Jing Guo, Yong Kang
摘要: Two laboratory-scale up-flow anaerobic sludge granules reactors were operated as control reactor (R1) and chitosan (CTS) addition reactor (R2) to investigate the effect of the addition of CTS on the granulation process of sulfate-reducing bacteria (SRB) anaerobic sludge. Granular sludge with the diameter greater than 0.5 mm was selected to calculate the granulation percentage, and the remaining sludge was considered as flocculent sludge in this paper. The results showed that the granulation percentage in the two reactors were stabilized to 47.3% and 64.2%, respectively. The sizes of sludge granules in R2 were mainly between 0.5 and 1.5 mm with the average pore diameter of 91.6 nm and the porosity of 57.1% while the granules in the same particle size in R1 were 41.5 nm and 46.1%, respectively. It demonstrated that CTS was an appropriate additive which can enhance the formation of SRB granule sludge with better pore structure. The granular sludge with CTS exhibited excellent physical performance and more extracellular polymeric substances, especially for protein (PN). In addition, computational fluid dynamics (CFD) simulation was conducted to illustrate the hydrodynamic characteristics of granules with Kozeny-Carman model. With a higher porosity, the permeability of the granules fed with CTS was considerably increased. Moreover, the model also indicated that the permeability and convection changed significantly with Reynolds numbers (Re) of the external flow field for a given type of the porous structure.
14590. 题目: Bioremediation of copper by active cells of Pseudomonas stutzeri LA3 isolated from an abandoned copper mine soil
期刊: Journal of Environmental Management
作者: Thenmozhi Murugaian Palanivel, Nallusamy Sivakumar, Aliya Al-Ansari, Reginald Victor
摘要: Copper bioremoval efficiency and bioaccumulation capacity of Pseudomonas stutzeri LA3 isolated from copper contaminated soil were investigated. P. stutzeri LA3 removed about 50% of Cu (II) at 50 mg l−1 of concentration and accumulated a maximum of 1.62 mg of Cu g−1 biomass dry weight. Bioremediation by P. stutzeri LA3 partially depended on the production of extracellular polymeric substances, composed of proteins and carbohydrates. Cell surface alterations were observed on the Cu (II) treated biomass through a scanning electron microscope (SEM). Energy dispersive spectrometer (EDX) investigation of Cu (II) treated biomass showed clear signals of Cu, confirming the presence of copper ions on the cell surface. Fourier transform infrared spectroscopy (FTIR) showed the contribution of functional groups such as hydroxyl (–OH), carboxyl (–COOH), amide and amine (–NH2) in the remediation process. Based on the results, the isolated strain P. stutzeri LA3 could serve as a potential candidate for copper due to its significant copper removal effeciency.
14591. 题目: Straw management influences the stabilization of organic carbon by Fe (oxyhydr)oxides in soil aggregates
作者: Bin Xue, Li Huang, Yanan Huang, Kashif Ali Kubar, Xiaokun Li, Jianwei Lu
摘要: The association of soil organic carbon (SOC) with Fe (oxyhydr)oxides is a major SOC stabilization process. However, the effects of straw incorporation on the role of Fe (oxyhydr)oxides in stabilization of SOC composition in aggregates have not been fully explored. The objective of this study was to explore the effect of straw incorporation on the relationship between iron oxides and SOC in soil aggregates in the rice-rape cropping system. In this study, SOC concentration, soil iron fractions and SOC composition in soil aggregates were analyzed. Soil samples were collected under two treatments, conventional tillage without straw incorporation (T) and conventional tillage with straw incorporation (TS), from surface 0–20 cm layer in 10-year and 6-year experiments in Wuxue City (WX) and Jingzhou City (JZ) in China. Compared with the T treatment, the TS treatment increased the proportion of >2 mm aggregates and decreased the proportion of aggregates of other sizes. Except for the 0.25–2 mm aggregates at WX, TS treatment increased the SOC concentration in the aggregates by 36–39% and 20–40% at WX and JZ, respectively, compared with the T treatment. Straw incorporation increased the abundance of alkyl C and the alkyl C/O-alkyl C ratio (an SOC decomposition index), but it slightly decreased the abundance of O-alkyl C at WX, which was opposite to the trend at JZ. Meanwhile, TS treatment increased the abundance of aromatic C in the silt + clay fraction (<0.053 mm) at WX and in aggregates (>0.25 and 0.053–0.25 mm) at JZ. Additionally, straw incorporation decreased the aliphatic C/aromatic C ratio (an SOC complexity index) in the <0.25 mm fraction at WX and in the >0.25 mm fraction at JZ. Furthermore, straw incorporation promoted the accumulation of poorly crystalline (Feo) and organically complexed (Fep) Fe (oxyhydr)oxides in aggregates. Feo was also significantly and positively correlated with the proportion of aromatic C (r = 0.617, P < 0.05) and carbonyl C (r = 0.801, P < 0.05) in the organic matter at WX experimental site. In conclusion, straw incorporation drives the formation of SOC-Fe (oxyhydr)oxides association in aggregates, thus contributing to soil organic carbon stabilization in paddy soils.
14592. 题目: Mineral control of organic carbon storage in acid temperate forest soils in the Basque Country
作者: Nahia Gartzia-Bengoetxea, Iñigo Virto, Ander Arias-González, Alberto Enrique, Oihane Fernández-Ugalde, Pierre Barré
摘要: Soil minerals are known to play a major role in soil organic carbon (SOC) stabilization. However, the exact nature of the role is still poorly understood as comparative studies are complicated by the fact that mineralogy usually varies with other important factors such as climate, land-use, texture and acidity. This study investigated naturally-occurring minerals and C storage in nine mature, second-rotation Pinus radiata D. Don forest plantations at a similar development stage and growing under similar climatic conditions, but established on soils derived from three different parent materials: sandstone, basalt and trachyte. We quantified the SOC stocks in the 0–20 cm soil layer, clay-size minerals and metal oxides. The distribution of SOC in labile and mineral-bound fractions and the chemical structure of the SOC were also determined, by CPMAS NMR spectroscopy. For similar tree biomass, mean SOC storage was 2 times higher in the soils derived from basalt and 2.5 times higher in the soils derived from trachyte which were relatively rich in chlorite/vermiculite mixed layers and short-range order aluminium and iron forms, than in the sandstone-derived soils dominated by illite and with no short-range order aluminium. The parent material also affected the major C components of the SOC. Thus, the proportion of aromatic-C forms in the total SOC was higher in the sandstone-derived soil than in the soils of volcanic origin. Furthermore, the proportion of SOC in the mineral-bound fraction was around 30% in the sandstone-derived soil and around 50% in the volcanic soils. We conclude that estimates of ecosystem SOC stocks in acid temperate forest soils should include proxies for clay mineralogy, such as phyllosilicate minerals, contents of Fe and Al (hydr-) oxides and non-crystalline compounds. In addition, we recommend the inclusion of soil parent material as a proxy in models aimed at estimating regional SOC stocks.
14593. 题目: Nitrate sources and processes in the surface water of a tropical reservoir by stable isotopes and mixing model
期刊: Science of The Total Environment
作者: Widad Fadhullah, Nur Syahirah Yaccob, M.I. Syakir, Syahidah Akmal Muhammad, Fu-Jun Yue, Si-Liang Li
摘要: Nitrate is one of the primary nutrients associated with sedimentation and fuels eutrophication in reservoir systems. In this study, water samples from Bukit Merah Reservoir (BMR) were analysed using a combination of water chemistry, water stable isotopes (δ2H–H2O and δ18O–H2O) and nitrate stable isotopes (δ15N–NO3− and δ18O–NO3−). The objective was to evaluate nitrate sources and processes in BMR, the oldest man-made reservoir in Malaysia. The δ15N–NO3− values in the river and reservoir water samples were in the range +0.4 to +14.9‰ while the values of δ18O–NO3− were between −0.01 and +39.4‰, respectively. The dual plots of δ15N–NO3− and δ18O–NO3− reflected mixing sources from atmospheric deposition (AD) input, ammonium in fertilizer/rain, soil nitrogen, and manure and sewage (MS) as the sources of nitrate in the surface water of BMR. Nitrate stable isotopes suggested that BMR undergoes processes such as nitrification and mixing. Denitrification and assimilation were not prevalent in the system. The Bayesian mixing model highlighted the dominance of MS sources in the system while AD contributed more proportion in the reservoir during both seasons than in the river. The use of δ13C, δ15N, and C:N ratios enabled the identification of terrestrial sources of the organic matter in the sediment, enhancing the understanding of sedimentation associated with nutrients previously reported in BMR. Overall, the nitrate sources and processes should be considered in decision-making in the management of the reservoir for irrigation, Arowana fish culture and domestic water supply.
14594. 题目: Microbial utilization of low molecular weight organic carbon substrates in cultivated peats in response to warming and soil degradation
期刊: Soil Biology and Biochemistry
作者: Yuan Wen, Huadong Zang, Benjamin Freeman, Samuel Musarika, Chris D. Evans, David R. Chadwick, Davey L. Jones
摘要: Peatlands store vast amounts of carbon (C) within the global terrestrial biosphere. Drainage and cultivation of peat soils lead to rapid soil degradation and C losses, and this may worsen under warming as the soils are no longer protected by anaerobic conditions. To predict the rates of soil C loss and design effective mitigation strategies, it is important to understand what controls organic matter mineralization in these soils. Using the 0–10 cm soil depth of thick and thin (degraded) agricultural peat soils, we investigated the fate of low molecular weight organic substrates (LMWOS) and how the microbial biomass consuming these substrates responded to temperature. We incubated the soils under increasing temperatures (4, 10, 20, and 30 °C) for 72 h. Either 14C-labelled glucose or amino acids were added to the soils and their speed of breakdown, partitioning into anabolic/catabolic processes and microbial C use efficiency (CUE) were determined. The total 14CO2 loss from soil increased significantly with increasing temperature during 72-h incubation, regardless of peat layer thickness. Warming altered the dynamics of LMWOS mineralization by changing C allocation and turnover rate of different pools. The half-life of LMWOS decreased more than 50% when temperature increased from 4 to 30 °C for both substrates. CUE was always higher for thin than thick peat soil and both declined by 0.002–0.005 °C-1 with temperature increase. Thin peat decreased substrate C allocation into the fast cycling pool compared to the thick peat, but had no overall effect on pool turnover rate. Our work suggests that climate warming will accelerate C mineralization and turnover in drained peat soils, with larger effects expected in thick peat soil. This study provides an important initial step in characterizing the response of the microbial utilization of labile C to temperature change and soil degradation in cultivated peatlands.
14595. 题目: Mesophilic and thermophilic anaerobic digestion of aqueous phase generated from hydrothermal liquefaction of cornstalk: Molecular and metabolic insights
期刊: Water Research
作者: Huihui Chen, Shilai Hao, Zheng Chen, Sompong O-Thong, Jiajun Fan, James Clark, Gang Luo, Shicheng Zhang
摘要: The critical challenge of hydrothermal liquefaction (HTL) for bio-oil production from biomass is the production of large amounts of aqueous products (HTL-AP) with high organic contents. The present study investigated the anaerobic digestion (AD) performances of HTL-AP under both thermophilic and mesophilic conditions, and molecular and metabolic analysis were conducted to provide insights into the different performances. The results showed that thermophilic AD had lower COD removal efficiency compared to mesophilic AD (45.0% vs. 61.6%). Liquid chromatography coupled with organic carbon detection and organic nitrogen (LC-OCD-OND) analysis showed that both high molecular weight (HMW) and low molecular weight (LMW) compounds were degraded to some extent and more LMW acids (LMWA) and recalcitrant aromatic compounds were degraded in the mesophilic reactor, which was the main reason of higher COD removal efficiency. Phenyl compounds (e.g. phenol and 2 methoxyphenol), furans and pyrazines were the recalcitrant chemicals detected through GC-MS analysis. Fourier transform ion cyclone resonance mass spectrometry (FT-ICR-MS) analysis demonstrated the complexity of HTL-AP and the proportions of phenolic or condensed aromatic compounds increased especially in the thermophilic effluents. Metabolites analysis showed that the reasons contributing to the differences of mesophilic and thermophilic AD were not only related to the degradation of organic compounds (e.g. benzoate degradation via CoA ligation) in HTL-AP but also related to the microbial autogenesis (e.g. fatty acid biosynthesis) as well as the environmental information processing. In addition, the enrichment of Mesotoga, responsible for the high degradation efficiency of LMWA, and Pelolinea, involved in the degradation of phenyl compounds, were found in mesophilic reactor, which was consistent with higher removal of corresponding organics.
14596. 题目: Impact of isolated dissolved organic fractions from seawater on biofouling in reverse osmosis (RO) desalination process
期刊: Water Research
作者: Wenqiang Yin, Jia Shin Ho, Emile R. Cornelissen, Tzyy Haur Chong
摘要: The biofouling potential of three isolated dissolved organic fractions from seawater according to their molecular weights (MWs), namely, fractions of biopolymers (F·BP, MW > 1000 Da), humic substances and building blocks (F·HS&BB, MW 350–1000 Da), and low molecular weight compounds (F.LMW, MW < 350 Da) were characterized by assimilable organic carbon (AOC) content. The AOC/DOC ratio was in the order of F. LMW (∼35%) > F·BP (∼19%) > F·HS&BB (∼8%); AOC/DOC of seawater was ∼20%; organic compositions of seawater were BP ∼6%, HS&BB ∼52% and LMW ∼42%; LMW accounted for >70% of AOC in seawater. Their impact on SWRO biofouling in term of flux decline rate was in the order of F. LMW (∼30%) > F·BP (∼20%) > F·HS&BB (<10%). Despite being the major organic compound in seawater, HS&BB showed marginal effect on biofouling. The role of indigenous BP was less critical owing to its relatively low concentration. LMW, which was the major AOC contributor, played a significant role in biofouling by promoting microbial growth that contributed to the build-up of soluble microbial products and exopolymeric substances (i.e., in particular BP). Therefore, seawater pretreatment shall focus on the removal of AOC (i.e., LMW) rather than the removal of biopolymer.
14597. 题目: Experimental redox transformations of uranium phosphate minerals and mononuclear species in a contaminated wetland
期刊: Journal of Hazardous Materials
作者: Lucie Stetten, Pierre Lefebvre, Pierre Le Pape, Arnaud Mangeret, Pascale Blanchart, Pauline Merrot, Jessica Brest, Anthony Julien, John R. Bargar, Charlotte Cazala, Guillaume Morin
摘要: Reducing conditions and high organic carbon content make wetlands favorable to uranium (U) sequestration. However, such environments are subjected to water-table fluctuations that could impact the redox behavior of U and its mobility. Our previous study on U speciation in a contaminated wetland has suggested a major role of water-table redox fluctuations in the redistribution of U from U(IV)-phosphate minerals to organic U(VI) and U(IV) mononuclear species. Here, we investigate the mechanisms of these putative processes by mimicking drying or flooding periods via laboratory incubations of wetland samples. LCF-XANES and EXAFS analyses show the total oxidation/reduction of U(IV)/U(VI)-mononuclear species after 20 days of oxic/anoxic incubation, whereas U-phosphate minerals are partly oxidized/reduced. SEM-EDXS combined with μ-XRF and μ-XANES analyses suggest that autunite Ca(UO2)2(PO4)2⋅11H2O is reduced into lermontovite U(PO4)(OH)⋅H2O, whereas oxidized ningyoite CaU(PO4)2⋅2H2O is locally dissolved. The release of U from this latter process is observed to be limited by U(VI) adsorption to the soil matrix and further re-reduction into mononuclear U(IV) upon anoxic cycling. Analysis of incubation waters show, however, that dissolved organic carbon enhances U solubilization even under anoxic conditions. This study brings important information that help to assess the long-term stability of U in seasonally saturated organic-rich contaminated environments.
14598. 题目: Changes in groundwater dissolved organic matter character in a coastal sand aquifer due to rainfall recharge
期刊: Water Research
作者: Liza K. McDonough, Denis M. O'Carroll, Karina Meredith, Martin S. Andersen, Clément Brügger, Hanxue Huang, Helen Rutlidge, Megan I. Behnke, Robert G.M. Spencer, Amy McKenna, Christopher E. Marjo, Phetdala Oudone, Andy Baker
摘要: Dissolved organic matter (DOM) in groundwater is fundamentally important with respect to biogeochemical reactions, global carbon cycling, heavy metal transport, water treatability and potability. One source of DOM to groundwater is from the transport of organic matter from the vadose zone by rainfall recharge. Changes in precipitation patterns associated with natural climate variability and climate change are expected to alter the load and character of organic matter released from these areas, which ultimately impacts on groundwater quality and DOM treatability. In order to investigate potential changes in groundwater DOM character after rainfall recharge, we sampled shallow groundwater from a coastal peat-rich sand aquifer in New South Wales, Australia, during an extended period of low precipitation (average daily precipitation rate < 1.6 mm day−1 over the 8 months prior to sampling), and after two heavy precipitation events (84 mm day−1 and 98 mm day−1 respectively). We assess changes in DOM composition after correcting for dilution by a novel combination of two advanced analytical techniques: liquid chromatography organic carbon detection (LC-OCD) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). We also assess changes in water chemistry pre- and post-rainfall. Post-rainfall, we show that the dilution-corrected amount of highly aromatic DOM molecular formulae (i.e. those categorised into the groups polyphenolics and condensed aromatics) were 1.7 and 2.0 times higher respectively than in pre-rainfall samples. We attribute this to the flushing of peat-derived DOM from buried organic material into the groundwater. We also identify that periods of low precipitation can lead to low hydrophilic/HOC ratios in groundwater (median = 4.9, n = 14). Redundancy analysis (RDA) was used to compare the HOC fraction with FT-ICR MS compound groups. We show that HOC has a more aromatic character in pre-rainfall samples, and is less similar to the aromatic groups in post-rainfall samples. This suggests that the decline in water-borne hydrophobics observed post-rainfall could be associated with preferential adsorption of the hydrophobic aromatic DOM, making post-rainfall samples less treatable for potable water supply. Post-rainfall we also observe significant increases in arsenic (leading to concentrations greater than 3 times the World Health Organisation drinking water limit of 10 μg/L). Increases in coastal rainfall due to climate change may therefore alter the composition of groundwater DOM in coastal peatland areas in ways that may impact DOM bioavailability, and increase arsenic concentrations, reducing the ease of water treatment for human consumption. To the best of our knowledge, this is the first study to identify the chemical and molecular changes of shallow groundwater DOM pre-rainfall and post-rainfall in a sedimentary organic carbon rich environment through multiple analytical techniques.
14599. 题目: Dissolved Organic Matter Export from Surface Sediments of a New England Salt Marsh
作者: Hayley N. Schiebel, Francesco Peri, Robert F. Chen
摘要: Salt marshes sequester a large amount of carbon via sedimentation, but seasonal and climate change impacts on sediment carbon biogeochemistry are not well-understood. This study investigates the export of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) from New England salt marsh sediment seasonally and under possible expected drought conditions. Surface sediment total organic carbon (TOC) values shifted seasonally depending on the overlying dominant plant species suggesting that vegetation and inundation frequency and duration are key factors in sediment TOC fluctuations. Fall sediment samples leached more DOC than summer samples, were compositionally similar to the estuarine water column, and compositionally different from fresh plant matter. Thus, the seasonal TOC pulse incorporated into surface sediments could be a dominant source of DOC to the estuary in the fall and that summer contributions are presumed to be from upstream DOM sources based on optical properties. Sediments leached more DOC under drought than non-drought conditions due to induced cracking in the sediment enhancing organic matter degradation. This study suggests the majority of DOM exported laterally from salt marshes comes from surface sediments (versus plant matter) and that temperature and sea-level rise could affect seasonal and drought pulses of DOC from the marsh.
14600. 题目: Angiosperm symbioses with non‐mycorrhizal fungal partners enhance N acquisition from ancient organic matter in a warming maritime Antarctic
期刊: Ecology Letters
作者: Paul W. Hill, Richard Broughton, Jeremy Bougoure, William Havelange, Kevin K. Newsham, Helen Grant, Daniel V. Murphy, Peta Clode, Soshila Ramayah, Karina A. Marsden, Richard S. Quilliam, Paula Roberts, Caley Brown, David J. Read, Thomas H. Deluca, Richard D. Bardgett, David W. Hopkins, Davey L. Jones
摘要: In contrast to the situation in plants inhabiting most of the world's ecosystems, mycorrhizal fungi are usually absent from roots of the only two native vascular plant species of maritime Antarctica, Deschampsia antarctica and Colobanthus quitensis. Instead, a range of ascomycete fungi, termed dark septate endophytes (DSEs), frequently colonise the roots of these plant species. We demonstrate that colonisation of Antarctic vascular plants by DSEs facilitates not only the acquisition of organic nitrogen as early protein breakdown products, but also as non‐proteinaceous d‐amino acids and their short peptides, accumulated in slowly‐decomposing organic matter, such as moss peat. Our findings suggest that, in a warming maritime Antarctic, this symbiosis has a key role in accelerating the replacement of formerly dominant moss communities by vascular plants, and in increasing the rate at which ancient carbon stores laid down as moss peat over centuries or millennia are returned to the atmosphere as CO2.