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24661. 题目: Biopolymers recovery: dynamics and characterization of alginate-like exopolymers in an aerobic granular sludge system treating municipal wastewater without sludge inoculum
文章编号: N20031224
期刊: Journal of Environmental Management
作者: Cássio Moraes Schambeck, Bruna Scandolara Magnus, Laís Cristina Rozone de Souza, Wanderli Rogério Moreira Leite, Nicolas Derlon, Lorena Bittencourt Guimarães, Rejane Helena Ribeiro da Costa
更新时间: 2020-03-12
摘要: Alginate-like exopolymers (ALE) are present in the extracellular polymeric substances (EPS) of biological sludge such as aerobic granular sludge (AGS). The recovery of ALE from excess sludge produced by wastewater treatment plants (WWTP) is a relevant approach for the recovery of valuable products of industrial interest. However, little is known about dynamics of ALE content in sludge and associated factors. Thus, this study aimed at assessing the dynamics of EPS and ALE in terms of content, some chemical properties and influencing environmental factors along granulation in a sequencing batch reactor treating municipal wastewater. Results indicated that the EPS content was not correlated with the development of AGS, while the ALE content was higher, more stable and steadily increased after granulation achievement. Overall, 236 ± 27 mg VSALE/g VSsludge was recovered from AGS and 187 ± 94 mg VSALE/g VSsludge from flocs. However, the lower ALE content in flocs may be compensated by the higher sludge production rate in activated sludge systems. Principal component analysis (PCA) revealed that ALE content positively correlates with the nutrient and organic substrate conversion, and with the fraction of large AGS. Microbial analyses indicated that a stable microbial community composition was associated with a higher and more stable ALE content. ALE recovered from both flocs and AGS was endowed with hydrogel property, and no clear difference in their elemental composition and functional groups was observed. Therefore, our study provides insights about quantitative and qualitative aspects of ALE which are helpful for the improvement of waste biological sludge valorization.

24662. 题目: Recycling and metabolic flexibility dictate life in the lower oceanic crust
文章编号: N20031223
期刊: Nature
作者: Jiangtao Li, Paraskevi Mara, Florence Schubotz, Jason B. Sylvan, Gaëtan Burgaud, Frieder Klein, David Beaudoin, Shu Ying Wee, Henry J. B. Dick, Sarah Lott, Rebecca Cox, Lara A. E. Meyer, Maxence Quémener, Donna K. Blackman, Virginia P. Edgcomb
更新时间: 2020-03-12
摘要: The lithified lower oceanic crust is one of Earth's last biological frontiers as it is difficult to access. It is challenging for microbiota that live in marine subsurface sediments or igneous basement to obtain sufficient carbon resources and energy to support growth1,2,3 or to meet basal power requirements4 during periods of resource scarcity. Here we show how limited and unpredictable sources of carbon and energy dictate survival strategies used by low-biomass microbial communities that live 10–750 m below the seafloor at Atlantis Bank, Indian Ocean, where Earth's lower crust is exposed at the seafloor. Assays of enzyme activities, lipid biomarkers, marker genes and microscopy indicate heterogeneously distributed and viable biomass with ultralow cell densities (fewer than 2,000 cells per cm3). Expression of genes involved in unexpected heterotrophic processes includes those with a role in the degradation of polyaromatic hydrocarbons, use of polyhydroxyalkanoates as carbon-storage molecules and recycling of amino acids to produce compounds that can participate in redox reactions and energy production. Our study provides insights into how microorganisms in the plutonic crust are able to survive within fractures or porous substrates by coupling sources of energy to organic and inorganic carbon resources that are probably delivered through the circulation of subseafloor fluids or seawater.

24663. 题目: Assessment of the molecular composition of humic acid as an indicator of soil carbon levels by ultra-high-resolution mass spectrometric analysis
文章编号: N20031222
期刊: Organic Geochemistry
作者: Marco A. Jiménez-González, Gonzalo Almendros, Derek C. Waggoner, Ana M. Álvarez, Patrick G. Hatcher
更新时间: 2020-03-12
摘要: Long-term stabilization of soil organic matter (SOM) plays an important role in the carbon cycle. Hence, understanding biogeochemical mechanisms of soil C sequestration is crucial to control its release to the atmosphere. This study aims at investigating the biogeochemical mechanisms of soil C sequestration. An exploratory assessment was carried out on the information about the soil C levels provided by the molecular composition of humic acids (HAs) analyzed by electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). Significant PLS forecasting model for total soil C was obtained using as descriptors the 131 compounds in common in all the HAs detected by FTICR-MS, and its variable importance for projection (VIP) was plotted in the space defined by their atomic ratios using van Krevelen diagrams. The results indicated that significant relationships exist between the HAs molecular composition and the soil organic C levels. The VIP values for the different groups of compounds illustrates how HA contains information about the amounts of C stored in the soil: the HAs in the soils with high levels of organic C have significantly (P < 0.1) higher proportions of unsaturated lipid and lignin-derived compounds; on the other side, low soil organic C levels are associated to HAs with comparatively high proportions of saturated lipid compounds.

24664. 题目: Assessment of the relationship between ACL/CPI values of long chain n-alkanes and climate for the application of paleoclimate over the Tibetan Plateau
文章编号: N20031221
期刊: Quaternary International
作者: Cunlin Li, Suping Ma, Yanqing Xia, Xiaobo He, Wenqiang Gao, Gaoqing Zhang
更新时间: 2020-03-12
摘要: Leaf wax n-alkanes are one of the most abundant molecular biomarkers, and they have tremendous potential for climate study. To understand the relationship between distribution characteristics of terrestrial higher plant long chain n-alkanes and climate, we assessed the correlation between average chain length (ACL25-33)/carbon preference index (CPI25-33) and mean annual temperature (MAT), growing season temperature (GST), and mean annual precipitation (MAP) and growing season precipitation (GSP) over the Tibetan Plateau (TP). It is important to note that the distribution characteristics of these long chain n-alkanes must be determined in surface soils and surface lake sediments. Statistical analysis and multi-proxy approaches (CPI and Paq) were applied to deal with this problem. The answer was that the long-chain n-alkanes corresponding to the conditions (CPI25-33≥5, aquatic macrophyte versus aquatic macrophyte and terrestrial plant ratio Paq≤0.20) were basically derived from terrestrial higher plants. Using these long chain n-alkanes to assess the correlation between ACL25-33/CPI25-33 and MAT, GST, MAP and GSP, we concluded that (i) weak positive correlations between ACL25-33 and MAT/GST were observed on the TP. Under high temperatures, the ACL values of terrestrial higher plants will increase to reduce cuticular transpiration. (ii) there are negative relationships between CPI25-33 and MAP/GSP. (iii) based on the studies of two proxies (ACL and CPI) for paleoclimate application, the long-chain n-alkane ACL25-33 may become a useful qualitative indicator of temperature change in paleoclimate studies from Xining Basin, Ximen Co, Glacially eroded lake, and Lake Dangxiong Co on the TP. CPI25-33 values might serve as a qualitative indicator of precipitation in paleoclimate studies when the plant species do not vary on the TP.

24665. 题目: The Effects of Water Chemistry on the Detachment and Dissolution of Differently Stabilized Silver Nanoparticles from Ceramic Membranes
文章编号: N20031220
期刊: Environmental Science: Water Research & Technology
作者: Anne Mikelonis, Lewis Stetson Rowles III, Desmond Lawler
更新时间: 2020-03-12
摘要: Silver nanoparticles (Ag NPs) are an attractive addition to membranes used for drinking water treatment due to their antimicrobial properties. This research examined the role of stabilizing agents, used during the synthesis of Ag NPs, on their detachment/dissolution from ceramic membranes exposed to different types of drinking water sources typical in the United States. Ag NPs that had been stabilized by citrate, polyvinylpyrrolidone (PVP), or branched polyethylenimine (BPEI) were deposited on the surface of porous aluminum oxide membranes. Results demonstrated that Ag NP stabilizer influenced removal from the membranes. For Ag NPs electrostatically stabilized (citrate), hard water was found to remove the Ag NPs for longer periods of time and at higher quantities than in water without hardness. The reverse was found for sterically stabilized Ag NPs (BPEI and PVP). Additions of natural organic matter (NOM) were added to waters filtered by membranes coated in citrate Ag NPs and were found to prolong the detachment of the citrate Ag NPs in the hard water test condition. Variations in total silver released from ceramic membranes were explained by differential impacts on the NP and membrane’s electrical double layers when switching from Ag NP deposition to filtration water chemistry conditions (zeta potential measurements are provided in this paper). Despite these differences, our findings show that, in waters that do not contain NOM, Ag release quickly falls below silver drinking water standards (0.1 mg/L) and greater than 50% remained on the membranes.

24666. 题目: Climate-zone-dependent effect mechanism of humic acid and fulvic acid extracted from river sediments on aggregation behavior of graphene oxide
文章编号: N20031219
期刊: Science of The Total Environment
作者: Jawad Ali, Yang Li, Xinjie Wang, Jian Zhao, Nannan Xi, Zhenrui Zhang, Xinghui Xia
更新时间: 2020-03-12
摘要: Climate factors could affect the physicochemical properties of dissolved organic matter (DOM) in river sediments, which potentially influence the stability of nanoparticles in natural waters. In this study, we extracted humic acid (HA) and fulvic acid (FA) from river sediments in different climate zones of China. Their effect with different concentrations (0.2 and 1 mg·C·L−1) on the aggregation kinetics of large (589 nm) and small graphene oxide (GO, 200 nm) in NaCl solutions was investigated. Both concentrations of HA/FA significantly inhibited the aggregation of small GO because of the steric forces rendered by DOM. For large GO, the inhibition effect of HA on aggregation was higher than FA because of the higher molecular weight, longer carbon chain length, and more structure complexity of HA. Interestingly, with 0.2 mg·C·L−1 HA and large GO, Makou in Subtropical monsoon climate zone decreased the aggregation rate more significantly due to its larger molecular weight, while, Maqin in the Plateau and mountain (PM) climate zone with smaller molecular weight and greater hydrophobicity showed lower inhibition effect on the aggregation. One mg·C·L−1 FA with high polarity from Tangke in PM climate zone and Panjin from Temperate monsoon climate zone showed more stability ability towards large GO. Derjaguin-landau-verwey-overbeek (DLVO) theory indicated that the interaction energy barrier between GO particles dependent on physicochemical characteristics of DOM and GO size. Understanding the climate-zone-dependent effect of sediment DOM on stability of GO is essential for anticipating its fate in natural systems.

24667. 题目: Ecological drivers of methanotrophic communities in paddy soils around mercury mining areas
文章编号: N20031218
期刊: Science of The Total Environment
作者: Hua-Jing Tian, Jiao Feng, Li-Mei Zhang, Ji-Zheng He, Yu-Rong Liu
更新时间: 2020-03-12
摘要: Methanotrophs play a crucial role in mitigating methane (CH4) emission by oxidizing produced CH4 in paddy soils; however, ecological drivers of methanotrophic community in the soils around heavy metal contaminated areas remain unclear. In this study, we evaluated the effects of heavy metal pollution and soil properties on the abundance, diversity and composition of methanotrophic community in paddy soils from two typical mercury (Hg) mining regions in southwest China. The results of random forest and structure equation models suggest that both heavy metal content and soil nutrients greatly influenced the attributes of methanotrophic community. In general, the abundance and diversity of methanotrophs were negatively related to soil Hg content, but showed positive correlation with soil organic carbon content. However, the other metals (cadmium (Cd), nickel (Ni), lead (Pb), arsenic (As), zinc (Zn)) had inconsistent associations with the microbial indexes of methanotrophic community in the soil. Elevated levels of heavy metal and nutrients in the soils shifted the community composition of methanotrophs. For example, Pb, As and Zn contents had negative associations with the relative abundance of Methylocaldum. In addition, changes in the relative abundance of ecological clusters within the co-occurrence network of methanotrophs were related to metal contents and soil properties. Together, our findings provide novel insights into understanding ecological drivers of methanotrophic community in paddy soils around Hg mining regions, with important implications for mitigating CH4 emissions in terrestrial ecosystems.

24668. 题目: Characterization and role of derived dissolved organic matter on arsenic mobilization in alluvial aquifers of Punjab, Pakistan
文章编号: N20031217
期刊: Chemosphere
作者: Aroosa Malik, Ambreen Parvaiz, Nisbah Mushtaq, Ishtiaque Hussain, Tariq Javed, Hafiz Ur Rehman, Abida Farooqi
更新时间: 2020-03-12
摘要: Biogeochemical mobilization of arsenic in groundwater depends on the presence of dissolved organic matter (DOM) that likely promotes the As release, i.e., reductive dissolution, complexation, competition, and electron shuttling. We investigated the role of DOM in As release, along with its complete characterization, in the Indus plain of Pakistan, one of the worst arsenic impacted zones in the South Asian region. In total, 60 groundwater and 15 soil samples, collected at six sites from north to south within the flood plain of the Ravi River, Lahore, Pakistan were investigated. Arsenic concentration ranged from 9.61 μg/L to 386 μg/L in the groundwater samples (high As observed in areas close to the river). Dissolved organic carbon (DOC) in 29 groundwater samples ranged between 0 and 10.1 mg-C/L. A moderately positive correlation of As with DOC and Fe in the northern part of the study area suggest the reductive dissolution of FeOOH associated with dissolved organic matter (DOM). The reductive dissolution plays an essential role for As enrichment in the area evidenced by the lower concentrations of SO42−, NO3−, and PO34−and a non-correlative pattern with As. In contrast, a positive correlation of As with PO34−, DOC, and HCO3− in the southern part indicate competitive desorption behind the As release. Fluorescence excitation-emission matrix intensity data of DOM indicate the maximum presence of humic-like substances in the northern part that gradually shifts to aromatic, fulvic and protein type towards the southern part. Specific ultraviolet absorbance and fluorescence index display aromatic and terrestrial (allochthonous) sources of DOM near the riverbank and mixed (both allochthonous and autochthonous) source away from the river. The positive correlations of As with DOC and fluorescence intensity also attest that DOM played a vital role in the As mobilization in groundwater of the study area.

24669. 题目: Tracking the sources of allochthonous organic matter along a subtropical fluvial-estuarine gradient using molecular proxies in view of land uses
文章编号: N20031216
期刊: Chemosphere
作者: Ana Caroline Cabral, Ana Lúcia Lindroth Dauner, Fernanda Caroline Borato Xavier, Marina Reback Domingues Garcia, Marines Maria Wilhelm, Vanessa Cristina Gonçalves dos Santos, Sergio Antônio Netto, César C. Martins
更新时间: 2020-03-12
摘要: Sedimentary sterols and linear alkylbenzenes associated with allochthonous organic matter (AOM) inputs were studied in surface sediments along the Tubarão riverbed, South Brazil. These markers were analysed in terms of concentrations, diagnostic ratios and by using multivariate analyses to identify the main organic matter sources. It was necessary to integrate all these factors to distinguish the sources and determine sewage contamination. Phytosterols predominated over faecal sterols, but the contributions of livestock waste along the river (determined in 50% of the sites) were confirmed by the fingerprint analysis. Raw sewage contamination was verified at one site, according to the increased levels of sewage molecular markers and confirmed by the multivariate analyses and diagnostic ratios calibrated to this region. A possible synergistic effect between inorganic nanoparticles from coal mine waste and organic contaminants related to AOM input was suggested and should not be ignored since both activities severely contribute to the environmental changes in much of this fluvial-estuarine gradient from the South Atlantic.

24670. 题目: Nitro-oxidative signalling induced by chemically synthetized zinc oxide nanoparticles (ZnO NPs) in Brassica species
文章编号: N20031215
期刊: Chemosphere
作者: Árpád Molnár, Márk Papp, Dávid Zoltán Kovács, Péter Bélteky, Dóra Oláh, Gábor Feigl, Réka Szőllősi, Zsolt Rázga, Attila Ördög, László Erdei, Andrea Rónavári, Zoltán Kónya, Zsuzsanna Kolbert
更新时间: 2020-03-12
摘要: Due to their release into the environment, zinc oxide nanoparticles (ZnO NPs) may come in contact with plants. In elevated concentrations, ZnO NPs induce reactive oxygen species (ROS) production, but the metabolism of reactive nitrogen species (RNS) and the consequent nitro-oxidative signalling has not been examined so far. In this work, Brassica napus and Brassica juncea seedlings were treated with chemically synthetized ZnO NPs (∼8 nm, 0, 25 or 100 mg/L). At low dose (25 mg/L) ZnO NP exerted a positive effect, while at elevated concentration (100 mg/L) it was toxic to both species. Additionally, B. juncea was more tolerant to ZnO NPs than B. napus. The ZnO NPs could enter the root cells due to their small (∼8 nm) size which resulted in the release of Zn2+ and subsequently increased Zn2+ content in the plant organs. ZnO NPs disturbed superoxide radical and hydrogen peroxide homeostasis and modulated ROS metabolic enzymes (NADPH oxidase, superoxide dismutase, ascorbate peroxidase) and non-enzymatic antioxidants (ascorbate and glutathione) inducing similar changes in oxidative signalling in both Brassica species. The homeostasis of RNS (nitric oxide, peroxynitrite and S-nitrosoglutathione) was also altered by ZnO NPs; however, changes in nitrosative signalling proved to be different in the examined species. Moreover, ZnO NPs triggered changes in protein carbonylation and nitration. These results suggest that ZnO NPs induce changes in nitro-oxidative signalling which may contribute to ZnO NP toxicity. Furthermore, difference in ZnO NP tolerance of Brassica species is more likely related to nitrosative than to oxidative signalling.

24671. 题目: Effect of soil type on the degradation of polychlorinated biphenyls in a pyrophosphate-chelated Fenton-like reaction
文章编号: N20031214
期刊: Chemical Engineering Journal
作者: Yi Sun, Ling Zhao, Ying Teng
更新时间: 2020-03-12
摘要: Little information can be obtained about the effect of soil type on the degradation of polychlorinated biphenyls (PCBs) in the pyrophosphate (PP)-chelated Fenton-like reaction that has been proven as a promising means for soil remediation. Thus, red soil (RS), paddy soil (PS), fluvo-aquic soil (FS), and black soil (BS) were chosen as representative soils located in different regions of China to systematically investigate effects of soil type on the degradation efficiency and initial rate constant (k) of PCBs in the PP-chelated Fenton-like reaction. Effects of soil type on the degradation efficiency of PCBs markedly depended on the Fe/PP ratio in the presence of enough H2O2. The degradation efficiency of PCBs in four soil slurries showed significant differences at a Fe/PP ratio of either 2:1 or 1:2, but no significant difference was observed at a Fe/PP ratio of 1:1, which was attributed to the discrepant contributions of soil constituents in four soils at three PP dosages. Hydroxyl radical (HO·) and k values followed the same order of RS > BS > PS > FS within 1 h under the optimal condition, which was an integrated result of the amount of soluble Fe3+ and the availability of H2O2. Two pathways were proposed as the influence mechanisms of soil type on the degradation kinetics of PCBs. One was the diverse availability of H2O2 among four soils mainly caused by both SOM and carbonate, and another was the different amounts of soluble Fe3+ among four soils primarily controlled by soil constituents through adsorption and hydrolysis pathways.

24672. 题目: Assessing branched tetraether lipids as tracers of soil organic carbon transport through the Carminowe Creek catchment (southwest England)
文章编号: N20031213
期刊: Biogeosciences
作者: Jingjing Guo, Miriam Glendell, Jeroen Meersmans, Frédérique Kirkels, Jack J. Middelburg, Francien Peterse
更新时间: 2020-03-12
摘要: Soils represent the largest reservoir of organic carbon (OC) on land. Upon mobilization, this OC is either returned to the atmosphere as carbon dioxide (CO2), or transported and ultimately locked into (marine) sediments, where it will act as a long-term sink of atmospheric CO2. These fluxes of soil OC are, however, poorly quantified, mostly due to the lack of a soil-specific tracer. In this study, a suite of branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are membrane lipids of soil bacteria, is tested as specific tracers for soil OC from source (soils under arable land, ley, grassland and woodland) to sink (Lake Loe Pool sediments) considering a small catchment located in southwest England (i.e. Carminowe Creek draining into Lake Loe Pool). The analysis of brGDGTs in catchment soils reveals that their distribution is not significantly different across different land use types (p > 0.05), and thus does not allow tracing land use-specific soil contributions to Lake Loe Pool sediments. Furthermore, the significantly higher contribution of 6-methyl brGDGT isomers in creek sediments (isomerization ratio (IR) = 0.48 ± 0.10; mean ± s.d., standard deviation; p 5ME = 0.46 ± 0.02 in creek bed sediment and 0.38 ± 0.01 in lake core sediment; p

24673. 题目: The partitioning of litter carbon fates during decomposition under different rainfall patterns: a laboratory study
文章编号: N20031212
期刊: Biogeochemistry
作者: Xu Yang, Katalin Szlavecz, Scott L. Pitz, J. Adam Langley, Chih-Han Chang
更新时间: 2020-03-12
摘要: During litter decomposition, three major fates of litter carbon (C) are possible: emission as carbon dioxide (CO2) into the atmosphere, leaching of dissolved organic carbon (DOC), and translocation and transformation into soil organic carbon (SOC). Soil moisture, one of the key drivers of litter decomposition, is predicted to change in the future due to shifts in precipitation patterns. We explored the effects of low, medium and high rainfall intensities on the partitioning of litter carbon fates in a 6-month long laboratory experiment. We tracked carbon in 13C-labeled tulip poplar litter in a laboratory mesocosms by measuring respiration rates, dissolved organic carbon in the leachate, and soil organic carbon at the end of the experiment. Mesocosms with the same three rainfall intensities but without leaf litter were also set up. Leaching of labile carbon caused priming, but the effect was stronger in the low intensity treatment. Transport of litter-derived carbon also differed: in high intensity treatment there was more total carbon in the surface soil and more litter-derived carbon in in the deep soil layers. The cumulative CO2 efflux was not significantly different. Our results highlight that extreme rainfall events, as projected by most climate models, may lead to altered carbon cycling in temperate forest soils.

24674. 题目: Selective removal of color substances by carbon-based adsorbents in livestock wastewater effluents
文章编号: N20031211
期刊: Environmental Geochemistry and Health
作者: Hyojeon Kim, Yeo-Myeong Yun, Kyeong-Ho Lim, Quoc Cuong Do, Seoktae Kang
更新时间: 2020-03-12
摘要: Livestock wastewater effluent generated after the anaerobic treatment process contains the considerable amount of color-causing organic matter. In this study, a quantitative comparison of three carbon-based adsorbents included granular activated carbon (GAC), expanded graphite (EG), and multi-walled carbon nanotubes (MWNTs) was carried out for the potential application to the removal of color substances, and their mechanism was proposed. Although GAC showed the highest specific dissolved organic carbon (DOC) adsorption capacity, the color removal efficiency was the smallest among three adsorbents. The selective color removal ratios of EG and MWNTs reached 22.7 ± 0.1 PtCo/mg-DOC-removed and 21.2 ± 0.1 PtCo/mg-DOC-removed, respectively, while that of GAC was only 12.3 ± 0.1 PtCo/mg-DOC-removed. The selective adsorption of color substances by graphene-based carbon materials was due to the aromatic π–π interaction between organic matter and the hexagonal carbon lattice of graphene. The analysis of molecular weight distribution also confirmed that the exposed surface area and macro-pores were responsible for the adsorption of high molecular weight color substances. The chemical regeneration of three adsorbents was examined using 1% NaOCl solution and MWNTs showed almost complete recovery of the initial color removal capacity. In conclusion, MWNTs were the most suitable carbon nanomaterial for the selective color removal from livestock wastewater effluent.

24675. 题目: Sorption of aromatic organophosphate flame retardants on thermally and hydrothermally produced biochars
文章编号: N20031210
期刊: Frontiers of Environmental Science & Engineering
作者: Ziwen Du, Chuyi Huang, Jiaqi Meng, Yaru Yuan, Ze Yin, Li Feng, Yongze Liu, Liqiu Zhang
更新时间: 2020-03-12
摘要: Aromatic organophosphate flame retardant (OPFR) pollutants and biochars are commonly present and continually released into soils due to their increasingly wide applications. In this study, for the first time, the sorption of OPFRs on biochars was investigated. Although triphenyl phosphate (TPhP) and triphenylphosphine oxide (TPPO) have similar molecular structures and sizes, TPhP exhibited much faster and higher sorption than TPPO due to its stronger hydrophobicity, suggesting the dominant role of hydrophobic interactions in TPhP sorption. The π-π electron donor-acceptor (EDA) interactions also contributed to the sorption process, as suggested by the negative correlation between the sorption capacity of the aromatic OPFRs and the aromatic index (H/C atomic ratios) of biochar. Density functional theory calculations further showed that one benzene ring of aromatic OPFRs has no electrons, which may interact with biochar via π-π EDA interactions. The electrostatic attraction between the protonated P = O in OPFRs and the negatively charged biochar was found to occur at pH below 7. This work provides insights into the sorption behaviors and mechanisms of aromatic OPFRs by biochars.

24676. 题目: Fractionation and chemical structure of dissolved organic matter in the rhizosphere associated with cadmium accumulation in tobacco lines (Nicotiana tabacum L.)
文章编号: N20031209
期刊: Environmental Science and Pollution Research
作者: Ming Zhao, Tingxuan Li, Haiying Yu, Xizhou Zhang, Zicheng Zheng, Yongdong Wang, Tao Liu, Dharmendra K. Gupta, Huagang Huang
更新时间: 2020-03-12
摘要: Reducing cadmium (Cd) accumulation in flue-cured tobacco is the main degree to reduce the harm of Cd to human health. In this study, a rhizobag experiment was conducted to investigate the characteristics of dissolved organic matter (DOM) in the rhizosphere of a low-Cd-accumulating tobacco line (RG11) and its role in the processes of Cd accumulation by plants. Cd concentrations in the roots and leaves of RG11 were 24.09–25.30 and 31.08–34.41% lower, respectively, than those of Yuyan5 under Cd stress. Cd exposure promoted DOM accumulation in the rhizosphere soils of the two tobacco lines. DOM concentrations in the rhizosphere soils of RG11 were 8.29–14.31% lower than those of Yuyan5 under Cd stress. RG11 presented less hydrophilic acid and hydrophilic base fractions, along with more hydrophobic acid and hydrophobic base fractions of DOM in the rhizosphere than those of Yuyan5 under Cd exposure. Fourier transform infrared spectroscopy results showed that RG11 exhibited less O–H, C–H, C=C, COO–, and C–O functional groups in rhizosphere DOM than those of Yuyan5 under Cd stress. Thus, the DOM in the rhizosphere of RG11 showed lower ability to solubilize Cd in soils, resulting in less Cd uptake by roots. This could be considered to be one of the important mechanisms of low Cd accumulation in leaves of RG11.

24677. 题目: Transesterification activity of modified biochars from spent malt rootlets using triacetin
文章编号: N20031208
期刊: Journal of Cleaner Production
作者: Maria Ntaflou, John Vakros
更新时间: 2020-03-12
摘要: In this study, transesterification of triacetin was studied using biochar as a greener and environmentally friendly solid catalyst. Biochar and modified biochars were produced from spent malt rootlets with pyrolysis at 850 °C in limited oxygen atmosphere, treated with acid, base, or pure water, characterized with various physicochemical techniques, like N2 adsorption for the determination of Specific Surface Area, thermogravimetric analysis, Infra-Red spectroscopy, Xray powder diffraction and Potentiometric Mass Titration for the determination of acid-base behavior and tested for their transesterification activity. The physicochemical characterization of the biochars showed that the treatment had significant effect on the specific surface area, TGA curves and point of zero charge of the biochars. Treatment with NaOH results to a significant increase in point of zero charge of the biochar, removal of lignin and enrichment of Na on the surface of biochar. Treatment with H2SO4 increases the specific surface area and the microporosity, lowers the point of zero charge and removes almost completely the mineral deposits from the surface. It was found that the two most active biochars were the untreated and the treated with NaOH biochar. The transesterification activity is correlated well with the basicity of the samples. The activity of the biochars is similar to the activity obtained in homogenous catalysis and it is stable for at least 3 cycles. The results are promising and biochars from spent malt rootlets can be used in transesterification reaction for biofuels production.

24678. 题目: A Novel Strategy to Evaluate the Aromaticity Degree of Natural Organic Matter Based on Oxidization-Induced Chemiluminescence
文章编号: N20031207
期刊: Environmental Science & Technology
作者: Jitao Lv, Ruixia Han, Lei Luo, Xiangyun Zhang, Shuzhen Zhang
更新时间: 2020-03-12
摘要: Due to its complex composition and structure, many of the properties of natural organic matter (NOM) are poorly understood. In this study, the oxidization-induced chemiluminescence (OCL) of NOM was investigated, and a flow-injection OCL method was developed using alkaline persulfate-H2O2 as the oxidizing agent. The method is suitable for the direct analysis of NOM in both homogeneous and heterogeneous samples without isolation or concentration. A strong linear relationship (p < 0.001) was found between the normalized organic carbon OCL (OCLOC) and the percentage of aromatic carbon in standard NOM and soil samples, suggesting that OCLOC can be used as an empirical indicator to assess the aromaticity degree of NOM in both homogeneous and heterogeneous samples. By using this method, the percentages of aromatic carbon in a forest soil profile with low organic carbon content were estimated, and a decrease in the degree of aromaticity in deeper soil was observed. Considering the high sensitivity (lower than 0.1 mg C L–1) and throughput (13 s per detection) and low sample consumption (less than 1 mg) of the method, the proposed OCLOC indicator shows great promise for the high-throughput evaluation of the aromaticity degree of NOM for a wide variety of environmental and geochemical samples.

24679. 题目: AQDS and Redox-Active NOM Enables Microbial Fe(III)-Mineral Reduction at cm-Scales
文章编号: N20031206
期刊: Environmental Science & Technology
作者: Yuge Bai, Adrian Mellage, Olaf Arie Cirpka, Tianran Sun, Largus T. Angenent, Stefan B. Haderlein, Andreas Kappler
更新时间: 2020-03-12
摘要: Redox-active organic molecules such as anthraquinone-2,6-disulfonate (AQDS) and natural organic matter (NOM) can act as electron shuttles thus facilitating electron transfer from Fe(III)-reducing bacteria (FeRB) to terminal electron acceptors such as Fe(III) minerals. In this research, we examined the length scale over which this electron shuttling can occur. We present results from agar-solidified experimental incubations, containing either AQDS or NOM, where FeRB were physically separated from ferrihydrite or goethite by 2 cm. Iron speciation and concentration measurements coupled to a diffusion-reaction model highlighted clearly Fe(III) reduction in the presence of electron shuttles, independent of the type of FeRB. Based on our fitted model, the rate of ferrihydrite reduction increased from 0.07 to 0.19 μmol d–1 with a 10-fold increase in the AQDS concentration, highlighting a dependence of the reduction rate on the electron-shuttle concentration. To capture the kinetics of Fe(II) production, the effective AQDS diffusion coefficient had to be increased by a factor of 9.4. Thus, we postulate that the 2 cm electron transfer was enabled by a combination of AQDS molecular diffusion and an electron hopping contribution from reduced to oxidized AQDS molecules. Our results demonstrate that AQDS and NOM can drive microbial Fe(III) reduction across 2 cm distances and shed light on the electron transfer process in natural anoxic environments.

24680. 题目: Role of in Situ Natural Organic Matter in Mobilizing As during Microbial Reduction of Fe III -Mineral-Bearing Aquifer Sediments from Hanoi (Vietnam)
文章编号: N20031205
期刊: Environmental Science & Technology
作者: M. Glodowska, E. Stopelli, M. Schneider, A. Lightfoot, B. Rathi, D. Straub, M. Patzner, V. T. Duyen, M. Berg, S. Kleindienst, A. Kappler
更新时间: 2020-03-12
摘要: Natural organic matter (NOM) can contribute to arsenic (As) mobilization as an electron donor for microbially-mediated reductive dissolution of As-bearing Fe(III) (oxyhydr)oxides. However, to investigate this process, instead of using NOM, most laboratory studies used simple fatty acids or sugars, often at relatively high concentrations. To investigate the role of relevant C sources, we therefore extracted in situ NOM from the upper aquitard (clayey silt) and lower sandy aquifer sediments in Van Phuc (Hanoi area, Vietnam), characterized its composition, and used 100-day microcosm experiments to determine the effect of in situ OM on Fe(III) mineral reduction, As mobilization, and microbial community composition. We found that OM extracted from the clayey silt (OMC) aquitard resembles young, not fully degraded plant-related material, while OM from the sandy sediments (OMS) is more bioavailable and related to microbial biomass. Although all microcosms were amended with the same amount of C (12 mg C/L), the extent of Fe(III) reduction after 100 days was the highest with acetate/lactate (43 ± 3.5% of total Fe present in the sediments) followed by OMS (28 ± 0.3%) and OMC (19 ± 0.8%). Initial Fe(III) reduction rates were also higher with acetate/lactate (0.53 mg Fe(II) in 6 days) than with OMS and OMC (0.18 and 0.08 mg Fe(II) in 6 days, respectively). Although initially more dissolved As was detected in the acetate/lactate setups, after 100 days, higher concentrations of As (8.3 ± 0.3 and 8.8 ± 0.8 μg As/L) were reached in OMC and OMS, respectively, compared to acetate/lactate-amended setups (6.3 ± 0.7 μg As/L). 16S rRNA amplicon sequence analyses revealed that acetate/lactate mainly enriched Geobacter, while in situ OM supported growth and activity of a more diverse microbial community. Our results suggest that although the in situ NOM is less efficient in stimulating microbial Fe(III) reduction than highly bioavailable acetate/lactate, it ultimately has the potential to mobilize the same amount or even more As.