论文检索

总访问量：4521418次

总访客量：195828人

所有论文

22681. 题目: Complexation between dissolved silica and alginate molecules: Implications for reverse osmosis membrane fouling
文章编号: N20040207
期刊: Journal of Membrane Science
作者: Shu Wang, Xia Huang, Menachem Elimelech
更新时间: 2020-04-02
摘要: Dissolved silica and organic matter are major membrane foulants in desalination of brackish water and wastewater by reverse osmosis. However, the interaction between inorganic silica species and dissolved organic molecules and their combined impact on membrane fouling are poorly understood. In this study, we have used sodium silicate and sodium alginate as model inorganic and organic foulants, respectively. Membrane fouling experiments showed a cooperative effect between the dissolved silica and alginate macromolecules, which aggravated membrane fouling. The molecular interactions between sodium alginate and sodium silicate and the properties of the formed complexes were determined by X-ray diffraction and X-ray photoelectron spectroscopy. Results show that the crystallinity of the formed complexes decreased as we increased the ratio of silica in the silica-alginate mixture, indicating the formation of amorphous complexes. Full reflection Fourier transform infrared spectroscopy also confirms new functional groups following the interaction between silica and alginate. Isothermal titration calorimetry was also employed to quantitatively determine the binding parameters by measuring the heat change during the reaction. When binding occurs between silica and alginate, the measured adsorbed or released heat is used to determine the binding constants as well as the enthalpy and entropy changes. Our results suggest that the interaction between silica and alginate is spontaneously exothermic and dominated by noncovalent bonding. Our findings provide fundamental insights into the complexation between silica and alginate in reverse osmosis membrane fouling and highlight the binding mechanism between silica and alginate molecules.

22682. 题目: Impacts of organic matter on the toxicity of biosynthesized silver nanoparticles to green microalgae Chlorella vulgaris
文章编号: N20040206
期刊: Environmental Research
作者: Mehdi Khoshnamvand, Saeed Ashtiani, Yongsheng Chen, Jingfu Liu
更新时间: 2020-04-02
摘要: The increasing production of eco-friendly nanoparticles like biosynthesized nanoparticles (BNPs) calls for study on their environmental and biological safety. Herein, the impact of natural organic matter on the toxicity of BNPs was studied. Using leaf extract of herbal plant Allium fistulosum, the Allium fistulosum-silver nanoparticles (AF-AgNPs) were synthesized with the yield of around 100% and used to explore the impacts of natural organic matter (Suwannee river humic acid) on their toxicity to green microalgae Chlorella vulgaris. The results showed that the as-prepared AF-AgNPs could decrease the end-points of biomass and chlorophyll a content of C. vulgaris in a dose-dependent manner. In addition, AF-AgNPs enhanced algal aggregation and decreased size of cells, especially at higher concentrations. However, organic matter showed an ameliorative effect on the toxicity of AF-AgNPs, and significant enhancement of biomass and chlorophyll a content (p < 0.05) were observed in media treated with higher contents of AF-AgNPs. Organic matter could also prevent more cellular aggregation and size reduction of C. vulgaris. Our results are helpful for understanding the effects of organic matter on the toxicity of BNPs to aquatic organisms.

22683. 题目: Synthesized effects of proteomic and extracellular polymeric substance (EPS) revealing the enhanced hydrogen production by formed biofilm of photo-fermentative bacteria
文章编号: N20040205
期刊: Environment International
作者: Han-Quan Wen, Hong-Yu Ren, Guo-Jun Xie, Guang-Li Cao, De-Feng Xing, Nan-Qi Ren, Bing-Feng Liu
更新时间: 2020-04-02
摘要: Photo-fermentative hydrogen production, the new energy production alternative, was greatly enhanced by formed biofilm. To understand the mechanism of enhancement, the intracellular proteome and extracellular polymeric substance (EPS)i during biofilm formation were investigated in this work. Experimental results indicated that a possible and effective altered system could transfer light to hydrogen. Proteins were significantly regulated, for example those related with nitrogenase, flagellin, EPS transportation and DNA duplication were up-regulated while those concerned photosystem were down-regulated. It revealed these changes of proteins contributed to positive activity of key enzymes, improved communication system and increased total light utilization efficiency thus leading to enhanced capacity of hydrogen production. Besides above metabolic changes inside the cells, EPS secreted by the bacteria played an important role in hydrogen production and its yield decided the release of hydrogen. When EPS descended to a lower concentration during biofilm formation, it meant carbon source for EPS synthesis was reduced, and more energy and reducing power could be transferred into hydrogen energy. More importantly, this work found that composition and structure of EPS were efficiently influenced by the formation of biofilm, such as benzene and O-H structure, secondary protein structure and the kinds of protein, which were important to stable biofilm and efficient hydrogen production. Therefore, final hydrogen yield was improved by altered protein and EPS resulted from biofilm formation. This study demonstrated that formation of biofilm is an efficient, ecological and attracting way to the future bio-hydrogen production.

22684. 题目: Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant. Part 1: Insights from sediment properties and radiocesium distributions
文章编号: N20040204
期刊: Science of the Total Environment
作者: Yukio Tachi, Tomofumi Sato, Yosuke Akagi, Makoto Kawamura, Hideji Nakane, Motoki Terashima, Kenso Fujiwara, Kazuki Iijima
更新时间: 2020-04-02
摘要: In order to elucidate the radiocesium transport behaviors in natural environment, we systematically investigated sediments from the highly contaminated rivers of Ukedo and Odaka around the Fukushima Daiichi Nuclear Power Plant. We focused on determining the key factors controlling the radiocesium sorption and fixation, such as variations in the particle size, clay mineralogy, and organic matter (OM). The distribution patterns of the 137Cs concentration and particle size fractions were found to be similar for the two rivers, indicating that both clay and silt fractions contributed almost equally to the Cs sorption. The clay mineralogical composition evaluated using X-ray diffraction analysis showed that the relative contents of micaceous minerals were higher in the Ukedo River samples, whereas the relative contents of smectite and kaolinite were higher in the Odaka River samples. This implies that the sediments in both rivers were likely at different weathering stages due to the different geological settings in both catchments. The effects of OM on the sediment properties were also investigated by comparing the cation exchange capacity (CEC) and the radiocesium interception potential (RIP) of the two samples both with and without OM present. The CEC values were controlled by both the clay minerals and OM, and the RIP values increased significantly in the absence of OM. Such trends were correlated to the total organic carbon values, which may be used to understand the direct and indirect roles of OM in the sorption and fixation of Cs. These key differences in river sediment were attributed to the differences in the geological settings and weathering stages. These properties may contribute to the different sorption and fixation behaviors of radiocesium. In the second part paper, we further examined these behaviors and identified key factors by investigating their relationship to the sediment properties of both rivers.

22685. 题目: Riverine nitrate source apportionment using dual stable isotopes in a drinking water source watershed of southeast China
文章编号: N20040203
期刊: Science of the Total Environment
作者: Xu Shang, Hong Huang, Kun Mei, Fang Xia, Zheng Chen, Yue Yang, Randy A. Dahlgren, Minghua Zhang, Xiaoliang Ji
更新时间: 2020-04-02
摘要: It is crucial to quantitatively track riverine nitrate (NO3−) sources and transformations in drinking water source watersheds for preventing current and future NO3− pollution, and ensuring a safe drinking water supply. This study identified the significant contributors to riverine NO3− in Zhaoshandu reservoir watershed of Zhejiang province, southeast China. To achieve this goal, we used hydrochemistry parameters and stable isotopes of NO3− (δ15N-NO3− and δ18O-NO3−) accompanied with a Markov Chain Monte Carlo mixing model to estimate the proportional contributions of riverine NO3− inputs from atmospheric deposition (AD), chemical nitrogen fertilizer (NF), soil nitrogen (SN), and manure and sewage (M&S). Results indicated that the main form of riverine nitrogen in this region was NO3−, constituting ~60% of the total nitrogen mass on average (total organic nitrogen ~37% & ammonium ~3%). Variations in the isotopic signatures of NO3− demonstrated that microbial nitrification of NF, SN and M&S was the primary nitrogen transformation process within the Zhaoshandu reservoir watershed, whereas denitrification was minimal. A classical dual isotope bi-plot incorporating chloride concentrations suggested NF, SN and M&S were the major contributors of NO3− to the river. Riverine NO3− source apportionment results were further refined using the Markov Chain Monte Carlo mixing model, which revealed that AD, NF, SN and M&S contributed 7.6 ± 4.1%, 22.5 ± 12.8%, 27.4 ± 14.5% and 42.5 ± 11.3% of riverine NO3− at the watershed outlet, respectively. Finally, uncertainties associated with NO3− source apportionment were quantitatively characterized as: SN > NF > M&S > AD. This work provides a comprehensive approach to distinguish riverine NO3− sources in drinking water source watersheds, which helps guide implementation of management strategies to effectively control NO3− contamination and protect drinking water quality. Summary of the main finding from this works (Capsule) We utilized NO3− stable isotope analysis and a Markov Chain Monte Carlo mixing model to quantify riverine nitrate pollution sources in a drinking water source watershed in Zhejiang province, southeast China. Markov Chain Monte Carlo mixing model output showed that NF, SN and M&S were the dominant sources of riverine NO3− during the sampling period in Zhaoshandu watershed. Uncertainty analysis characterized the variation strength associated with contributions of individual nitrate sources and indicated the greatest uncertainty for SN, followed by NF, M&S and AD.

22686. 题目: Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant. Part 2: Sorption and fixation behaviors and their relationship to sediment properties
文章编号: N20040202
期刊: Science of the Total Environment
作者: Yukio Tachi, Tomofumi Sato, Chizuko Takeda, Takamitsu Ishidera, Kenso Fujiwara, Kazuki Iijima
更新时间: 2020-04-02
摘要: We systematically investigated the sorption and fixation behaviors of radiocesium (137Cs) for sediments taken from the rivers of Ukedo and Odaka around the Fukushima Daiichi Nuclear Power Plant. By comparing the Cs sorption and sequential desorption results at various Cs concentrations, across a range of sediment properties, we were able to understand the different contributions at frayed edge sites (FESs) and regular exchange sites (RESs) of the clay minerals, and their relationships with the Cs concentrations and the contents of organic matter (OM). The Cs sorption and fixation were dominated by FESs at trace Cs concentrations, and by ion exchange at RES and the collapse of interlayers at higher Cs concentrations. The Cs sorption at lower Cs concentration was strongly related to radiocesium interception potential (RIP); however, Cs fixation was more related to clay mineralogy (i.e. contents of mica, vermiculite and hydroxy-interlayered vermiculite) rather than the RIP. The first-order kinetic constants for time-dependent Cs sorption at low Cs concentrations were correlated negatively to the ratio between the total organic carbon and RIP values. This implies that Cs access to FESs requires a relatively long duration that is dependent on the contents of the OM. From these results, the sorption and fixation mechanisms were confirmed to be significantly different at different Cs concentrations. Then, the prediction of Cs transport should be based on the key mechanisms that are dominant at the actual trace levels of Cs. A significant difference between the Cs fixation behaviors at the Ukedo River and Odaka River may be understood by considering the differences in their clay mineralogy, due to the different geological settings and weathering stages of both catchments.

22687. 题目: The antimony sorption and transport mechanisms in removal experiment by Mn-coated biochar
文章编号: N20040201
期刊: Science of the Total Environment
作者: Xiaocen Jia, Jianwei Zhou, Jing Liu, Peng Liu, Lu Yu, Bing Wen, Yu Feng
更新时间: 2020-04-02
摘要: A method of Mn-coated biochar production was developed, which showed great removal ability of trivalent antimony (Sb(III)) (0.94 mg g−1) and pentavalent antimony (Sb(V)) (0.73 mg g−1), and the adsorption capacity was stable under different pH. According to the adsorption kinetics and isotherm, the adsorption process of both Sb(III) and Sb(V) was chemisorption, which was both monolayer and poly layers heterogeneous chemisorption process. X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy analyses indicated that the main oxides and functional groups involved in the adsorption were manganese oxides (MnOx), carboxyl and hydroxyl groups and Sb(V) was combined with Mn-coated biochar by inner-sphere complexation. Sb(III) was oxidized by oxygen and MnOx which was both on the surface of biochar and dissolved in solution. Furthermore, X-ray absorption near-edge structure (XANES) showed that Sb(V) was the main species after Sb(III) and Sb(V) adsorbed on the Mn-coated biochar. Extended X-ray absorption fine structure (EXAFS) analysis indicated that Sb(III) and MnOx formed the monodentate mononuclear and corner-sharing complexes with a structure of Mn-O-Sb on Mn-coated biochar. While Sb(V) and MnOx formed inner-sphere complexes including edge-sharing and corner-sharing complexes. The new synthetic material can contribute to develop new remediation strategies for treating Sb-contaminated water.

22688. 题目: Plastic-film mulch cropping increases mineral-associated organic carbon accumulation in maize cropped soils as revealed by natural 13C/12C ratio signature
文章编号: N20040114
期刊: Geoderma
作者: Qiu-Jin Ma, Qian Zhang, Jianbiao Niu, Xiao Gang Li
更新时间: 2020-04-01
摘要: Plastic-film mulch is used for increasing soil temperature and reducing water evaporation to enhance productivity in semiarid regions worldwide; however, its effects on soil organic carbon (SOC) level and stability are not clear. We tested hypotheses that increasing soil temperature and moisture by plastic-film mulch with an increase of carbon input would increase the accumulation of heavy-fraction SOC (HFOC) and decrease the mineralization potential of HFOC. Soils were sampled at 0–45 cm depth from four treatments: (i) no mulch and no straw incorporation, (ii) mulch only, (iii) straw incorporation only, and (iv) straw incorporation plus mulch. All treatments were cultivated with C4 maize (Zea mays L.) under ridge–furrow management continuously for nine years in a field previously planted with C3 crops in a cold environment. Proportionately to the increased aboveground biomass, root biomass in the 0–20 cm depth increased under mulch compared to no mulch. Nine years later, mulch reduced both maize-derived (new) and C3-crop-derived (old) light-fraction SOC (LFOC) stocks only at 0–15 cm soil depth compared to no mulch, regardless of whether straw was incorporated or not, reflecting the increased decomposition due to increased temperature and moisture in mulched soils. Mulch increased new HFOC stock at 0–30 cm soil depth relative to no mulch. These indicated that the faster decomposition of labile LFOC with increasing plant input under mulch relative to no mulch was paralleled by an enhancement in the accumulation of stable HFOC in mulched soils. Mulch enhanced the benefits of straw incorporation in terms of increasing the accumulation of new HFOC. Over nine years, the average sequestration rate of new HFOC at 0–45 cm soil depth was 204 (±18) and 266 (±10) kg ha−1 yr−1 without and with mulch, respectively, in non-straw-incorporated plots, and 514 (±14) and 752 (±18) kg ha−1 yr−1 without and with mulch, respectively, in straw-incorporated plots. Old HFOC was unaffected by mulch or straw incorporation. Overall, mulch did not change the total SOC storage in the top 45-cm soil. Mulch decreased the mineralization potential of new HFOC under laboratory incubation compared to no mulch, indicating that the new HFOC was more decomposed in mulched soils. We concluded that increasing soil temperature and moisture by using plastic-film mulch with high plant input increases the accumulation of stable HFOC in maize croplands.

22689. 题目: Molecular indicators of methane metabolisms at cold seeps along the United States Atlantic Margin
文章编号: N20040113
期刊: Chemical Geology
作者: Nancy G. Prouty, Pamela L. Campbell-Swarzenski, Hilary G. Close, Jennifer F. Biddle, Sabrina Beckmann
更新时间: 2020-04-01
摘要: Anaerobic oxidation of methane (AOM) and the environmental conditions supporting AOM on continental margins is an essential component to global methane budgets. Diagnostic lipid biomarkers and their compound specific isotope analysis preserved in authigenic carbonates at cold seeps can serve as fingerprints to archaeal−bacterial consortia involved in AOM. However, despite the discovery of several hundreds of seeps along the United States Atlantic Margin (USAM), there are relatively few biomarker investigations of cold seep carbonates along this passive margin. A lipid biomarker, carbon isotope, and DNA marker gene study was therefore undertaken to determine the microbial origins of authigenic carbonates from two USAM seeps, Norfolk and the Baltimore Canyon seep fields. Results from this study capture a distinct archaeal lipid signature from putative methanotrophic archaea, including archaeol (I), sn-2-hydroxyarchaeol, 2,6,10,15,19-pentamethylicosane (PMI), and crocetane. The 13C-depleted AOM-related archaeal lipid samples (i.e., archaeol: −91.6‰, sn-2-hydroxyarchaeol: −129.2‰, PMI −92.8‰, and crocetane: −70.9‰) confirm the dominance of methane assimilation and isotope fractionation during AOM. These results are consistent with the detection of archaeal anaerobic methanotrophs (ANMEs) based on 16S rRNA gene sequencing. The Norfolk authigenic carbonate contained ANME-1a, -1b, 2a-2b, and 2c whereas only the ANME-2 clade was detected at Baltimore and present as the subclusters 2a-2b and -2b. The ANME-2d clade may also be present, particularly at the Baltimore seep site, given the high abundance of Candidatus Methanoperedens nitroreducens detected in the mcrA gene sequencing. The presence of terminally branched fatty acids, antesio- and iso-C15:0 components, as well as C16:1ω7 with δ13C values as low as −107.6‰, are indicative of sulfate-reducing bacteria (SRB) at the Norfolk seep site and supports syntrophy of SRB with methane-oxidizing archaea. In contrast, nitrate-driven AOM in syntrophy M. nitroreducens at the Baltimore seep site is consistent with elevated fatty acid δ13C values and lack of Deltaproteobacteria at the Baltimore seep site. Taken together, the range in lipid composition, distribution, and carbon isotopic composition observed at the Norfolk and Baltimore seep sites suggests AOM is performed by multiple archaea instead of a single species and may be paired with either or both nitrate- and sulfate-reduction. Given the heterogeneous nature of cold seep ecosystems, this study fills a critical spatial gap in our knowledge of AOM activity at two seep sites along a passive margin.

22690. 题目: The effect of low-temperature biochar and its non-pyrolyzed composted biosolids source on the geochemical fractionation of Pb and Cd in calcareous river sediments
文章编号: N20040112
期刊: Environmental Earth Sciences
作者: Kerry Mitchell, Celeste Viridiana Mendoza-González, Magdalena Samanta Ramos-Gómez, Laura Yamamoto-Flores, Alma Lilian Guerrero-Barrera, Roberto Macias-Medrano, Francisco Javier Avelar-González
更新时间: 2020-04-01
摘要: Single extraction and sequential extraction assays were used to compare the effect of low-temperature biochar and its non-pyrolyzed composted biosolids on Pb and Cd mobility in the buffered conditions of calcareous river sediments. Results showed that amendment reduced the mobility of both metals, though under higher pH conditions, the effect of the non-pyrolyzed composted biosolids on the mobility of Pb was more apparent. On the other hand, the low temperature biochar had a more significant effect on the mobility of both metals under low pH conditions. The single extraction scheme used to simulate varying physicochemical conditions confirmed that amendment decreased Pb mobility up to 49% and Cd up to 96%. Sequential extraction assays confirmed a shift in predominant metal-fraction associations; from potentially mobile fractions to the more immobile ferromanganese oxide and organic matter fractions. These results highlighted the significant impact biochar amendment can have on metal mobility even when temporarily buffered by the physicochemical conditions in the calcareous substrates.

22691. 题目: Tradeoffs in soil carbon protection mechanisms under aerobic and anaerobic conditions
文章编号: N20040111
期刊: Global Change Biology
作者: Wenjuan Huang, Chenglong Ye, William Hockaday, Steven J. Hall
更新时间: 2020-04-01
摘要: Oxygen (O2) limitation is generally understood to suppress soil carbon (C) decomposition and is a key mechanism impacting terrestrial C stocks under global change. Yet, O2 limitation may differentially impact kinetic or thermodynamic vs. physico‐chemical C protection mechanisms, challenging our understanding of how soil C may respond to climate‐mediated changes in O2 dynamics. Although O2 limitation may suppress decomposition of new litter C inputs, release of physico‐chemically protected C due to iron (Fe) reduction could potentially sustain soil C losses. To test this tradeoff, we incubated two disparate upland soils that experience periodic O2 limitation—a tropical rainforest Oxisol and a temperate cropland Mollisol—with added litter under either aerobic (control) or anaerobic conditions for one year. Anoxia suppressed total C loss by 27% in the Oxisol and by 41% in the Mollisol relative to the control, mainly due to the decrease in litter‐C decomposition. However, anoxia sustained or even increased decomposition of native soil‐C (11.0% vs. 12.4% in the control for the Oxisol and 12.5% vs. 5.3% in the control for the Mollisol, in terms of initial soil C mass), and it stimulated losses of metal‐ or mineral‐associated C. Solid‐state 13C nuclear magnetic resonance spectroscopy demonstrated that anaerobic conditions decreased protein‐derived C but increased lignin‐ and carbohydrate‐C relative to the control. Our results indicate a tradeoff between physico‐chemical and kinetic/thermodynamic C protection mechanisms under anaerobic conditions, whereby decreased decomposition of litter C was compensated by more extensive loss of mineral‐associated soil C in both soils. This challenges the common assumption that anoxia inherently protects soil C and illustrates the vulnerability of mineral‐associated C under anaerobic events characteristic of a warmer and wetter future climate.

22692. 题目: Synthesis of calcite-based bio-composite biochar for enhanced biosorption and detoxification of chromium Cr (VI) by Zhihengliuella sp. ISTPL4
文章编号: N20040110
期刊: Bioresource Technology
作者: Arti Mishra, Bulbul Gupta, Naveen Kumar, Rashmi Singh, Ajit Verma, Indu Shekhar Thakur
更新时间: 2020-04-01
摘要: The current study presents a comprehensive analysis of the potential of actinobacterium Zhihengliuella sp. ISTPL4 and different composite materials for the removal of hexavalent chromium [Cr (VI)]. Genome analysis of strain indicated the presence of several oxidoreductases which includes chromate reductase, nitrate reductase, thioredoxin, superoxide dismutase and hydrogenase are other major candidate genes. Catalytic calcite-based bio-composite material was absorbed on biochar had highest Cr removal efficiency. The main mechanism involved in Cr biosorption by this strain was explained by the Langmuir isotherm model; under equilibrium conditions the maximum adsorption was observed 49± 0.3mgg−1. Kinetic studies showed that biosorption of Cr (VI) by this strain was a rate-limiting step and followed a pseudo-second-order kinetics (R2 =0.99). SEM analysis is in line with EDX result indicating highest Cr removal by calcined biochar. MTT assay shown that the bacteria successfully convert toxic Cr (VI) to comparatively less toxic form such as Cr (III).

22693. 题目: Enhanced volatile fatty acid degradation and methane production efficiency by biochar addition in food waste-sludge co-digestion: A step towards increased organic loading efficiency in co-digestion
文章编号: N20040109
期刊: Bioresource Technology
作者: Guneet Kaur, Davidraj Johnravindar, Jonathan W.C. Wong
更新时间: 2020-04-01
摘要: This work investigated the effect of biochar addition to mitigate VFA accumulation and enhance methane production in mesophilic food waste/sludge co-digestion. Different types of biochar derived from agricultural and forestry residues at two pyrolysis temperatures were tested. Results showed that wheat straw biochar 550 °C supported the highest specific methane yield of 381.9 LCH4/kg VSadded and VS removal efficiency of 41.62% among all treatments. Degradation of propionic acid and long-chain fatty acids such as valeric, caproic and isovaleric acids was observed. This also corresponded to an increase in methanogenic favorable substrates including acetic acid (>40%) and butyric acid (~20%) over the control. Consequently, a 24% increase in overall methane production was obtained as compared to control. This demonstrated that biochar addition had positive effects on VFA degradation and methane production which could be a useful strategy to increase the organic loading in co-digestions without the fear of process failure.

22694. 题目: Evaluating the performance of inorganic draw solution concentrations in an anaerobic forward osmosis membrane bioreactor for real municipal sewage treatment
文章编号: N20040108
期刊: Bioresource Technology
作者: Yue Gao, Zhou Fang, Cheng Chen, Xianzheng Zhu, Peng Liang, Yong Qiu, Xiaoyuan Zhang, Xia Huang
更新时间: 2020-04-01
摘要: Sewage can become a valuable source if its treatment is re-oriented for recovery. An anaerobic forward osmosis membrane bioreactor (AnOMBR) was developed for real municipal sewage treatment to investigate performance, biogas production, flux change and mixed liquor characteristics. The AnOMBR had a good treatment capacity with removal ratio of chemical oxygen demand, ammonia nitrogen, total nitrogen and total phosphorus more than 96%, 88%, 89% and almost 100%. Although high DS concentration increased the initial flux, it caused rapid decline and poor recoverability of FO membrane flux. Low DS concentration led to too long hydraulic retention time, thus resulting in a low reactor efficiency. Additionally, it was observed that salt, protein, polysaccharide and humic acid were all accumulated in the reactor, which was not conducive to stable long-term operation. Based on the characteristics of membrane fouling, salt accumulation and AnOMBR performance, the optimal DS of 1 M NaCl solution was selected.

22695. 题目: Nanoscale Pisum sativum pods biochar encapsulated starch hydrogel: A novel nanosorbent for efficient chromium (VI) ions and naproxen drug removal
文章编号: N20040107
期刊: Bioresource Technology
作者: Asmaa K. Mohamed, Mohamed E. Mahmoud
更新时间: 2020-04-01
摘要: Assembly of novel ecofriendly and sustainable (N-PSPB/SHGL) nanosorbent was fabricated based on encapsulation of derived nanoscale spherical biochar from Pisum sativum pods (N-PSPB) with starch hydrogel (SHGL). The mass ratio between starch and N-PSPB was examined and 2% (w/w) was selected as the optimum percentage for fabrication of the assembled hydrogel. High swelling capacity was characterized by N-PSPB/SHGL nanosorbent (500.0%) at room temperature (25°C), excellent stability for ten cycles with respect to regeneration by 0.1 mol L-1 HCl. Additionally, characterizations of N-PSPB/Starch nanosorbent were established by SEM and BET measurement to characterize surface area (226.94 m2/g) and pore volume (9.88 cm3/g). The N-PSPB/SHGL nanosorbent was subjected to extensive investigations to evaluate its efficiency for removal of naproxen drug (NAP) and chromium (VI). The Cr(VI) and NAP drug adsorptions were fitted to pseudo-second kinetic and correlated with Langmuir isotherm. The adsorption processes were spontaneous and endothermic based on thermodynamic study.

22696. 题目: Phosphorus Speciation in Atmospherically Deposited Particulate Matter and Implications for Terrestrial Ecosystem Productivity
文章编号: N20040106
期刊: Environmental Science & Technology
作者: Peggy A. O’Day, Ugwumsinachi G Nwosu, Morgan E. Barnes, Stephen C. Hart, Asmeret Asefaw Berhe, John N. Christensen, Kenneth H. Williams
更新时间: 2020-04-01
摘要: Chemical forms of phosphorus (P) in airborne particulate matter (PM) are poorly known and do not correlate with solubility or extraction measurements commonly used to infer speciation. We used P X-ray absorption near-edge structure (XANES) and 31P nuclear magnetic resonance (NMR) spectroscopies to determine P species in PM collected at four mountain sites (Colorado and California). Organic P species dominated samples from high elevations, with organic P estimated at 65–100% of total P in bulk samples by XANES and 79–88% in extracted fractions (62–84% of total P) by NMR regardless of particle size (≥10 or 1–10 μm). Phosphorus monoester and diester organic species were dominant and present in about equal proportions, with low fractions of inorganic P species. By comparison, PM from low elevation contained mixtures of organic and inorganic P, with organic P estimated at 30–60% of total P. Intercontinental PM transport determined from radiogenic lead (Pb) isotopes varied from 0 to 59% (mean 37%) Asian-sourced Pb at high elevation, whereas stronger regional PM inputs were found at low elevation. Airborne flux of bioavailable P to high-elevation ecosystems may be twice as high as estimated by global models, which will disproportionately affect net primary productivity.

22697. 题目: Heterogeneous Diffusion of Polystyrene Nanoparticles through an Alginate Matrix: The Role of Cross-linking and Particle Size
文章编号: N20040105
期刊: Environmental Science & Technology
作者: Joann M. Rodríguez-Suárez, Caitlyn S. Butler, Anne Gershenson, Boris L. T. Lau
更新时间: 2020-04-01
摘要: Most bacteria in natural and engineered environments grow and exist in biofilms. Recent investigations have shown that nanoparticles (NPs) interact with environmental biofilms, but these interactions are still not well characterized. Extracellular polymeric substances (EPS) are polymers secreted by bacteria to establish the functional and structural integrity of biofilms, and EPS porosity is a major contributor to NP access to and diffusion in biofilms. We used a synergistic combination of total internal reflection fluorescence microscopy and image correlation spectroscopy to monitor and map diffusion of fluorescent NPs in alginate yielding a detailed picture of the heterogeneous structure and connectivity of pores within a model EPS polymer. Using different sizes (20, 100, and 200 nm) of carboxylated polystyrene NPs, we examined how NP diffusive behaviors change as a result of calcium-induced cross-linking of the alginate matrix. This study reveals that cross-linking decreases NP diffusion coefficients and pore accessibility in an NP size-dependent manner and that NP movement through alginate matrices is anisotropic and heterogeneous. These results on heterogeneous and size-dependent movement within biofilms have important implications for future studies and simulations of NP-biofilm interactions.

22698. 题目: Changes in soil organic carbon fractions and residence time five years after implementing conventional and conservation tillage practices
文章编号: N20040104
期刊: Soil and Tillage Research
作者: Mehdi Rahmati, Iraj Eskandari, Mehdi Kouselou, Vali Feiziasl, Gholam Reza Mahdavinia, Nasser Aliasgharzad, Blair M. McKenzie
更新时间: 2020-04-01
摘要: Tillage not only affects the quantity of soil organic carbon, SOC, but also its quality. Therefore, an investigation was conducted to see how a five-year (2011–2016) implementation of conventional tillage, CT, and conservation tillage practices, CTP's, under dryland vetch – wheat farming system can affect the total organic carbon, TOC, of soil and its fractions as well as its biological indicators including the half-life of organic materials, HL, and the mean residence time, MRT. The applied tillage practices included three CTP's of reduced tillage, RT, with chisel plow, minimum tillage, MT, with stubble cultivator, and no-tillage, NT, with direct seeding as well as one conventional tillage, CT, with moldboard plow. The results revealed that all applied CTP's (RT, MT, and NT) significantly increased the TOC of examined surface soils (0−25 cm) compared to CT. The labile fraction of SOC (dissolve organic carbon, DOC) under CTP's, excluding NT, showed a significant decrease compared to CT. While MT significantly increased the fraction of organic carbon stabilized by clay and silt particles, OC{c + s} compared to CT, NT and RT made no considerable change in OC{c + s} compared to CT. There was also a considerable (but insignificant) increase in the amount of organic carbon stabilized by sand and aggregates plus particulate organic matter, OC{S + A+POM}, under CTP's compared to CT. We recorded the greatest (228 ± 21 μg N g−1 2 h−1) and least (98 ± 27 μg N g−1 2 h−1) activity of urease under RT and CT systems, respectively, and the differences were significant. Based on the incubation data, the NT and RT systems significantly resulted in highest HL, (170 ± 9 days) for soil organic materials while CT had the lowest HL, (127 ± 5 days). While RT showed significantly the highest aggregate stability (55 ± 7 %), the CT and MT had the lowest aggregate stability (29 ± 4 %). In general, our results demonstrated the benefits of CTP's, and more specifically the benefits of RT and NT systems, in improving SOC, as primary indicator of soil quality, in surface soils under dryland agriculture in terms of quantity and quality of organic carbon.

22699. 题目: Biochar enhanced the nitrifying and denitrifying bacterial communities during the composting of poultry manure and rice straw
文章编号: N20040103
期刊: Waste Management
作者: Mohd Huzairi Zainudin, Nurul Asyifah Mustapha, Toshinari Maeda, Norhayati Ramli, Kenji Sakai, Mohd Hassan
更新时间: 2020-04-01
摘要: Biochar has proven to be a feasible additive for mitigating nitrogen loss during the composting process. This study aims to evaluate the influence of biochar addition on bacterial community and physicochemical properties changes, including ammonium (NH4+), nitrite (NO2−) and nitrate (NO3−) contents during the composting of poultry manure. The composting was carried out by adding 20% (w/w) of biochar into the mixture of poultry manure and rice straw with a ratio of 2:1, and the same treatment without biochar was prepared as a control. The finished product of control compost recorded the high contents of NO2− and NO3− (366 mg/kg and 600 mg/kg) with reduced the total NH4+ content to 10 mg/kg. Meanwhile, biochar compost recorded a higher amount of total NH4+ content (110 mg/kg) with low NO2− and NO3− (161 mg/kg and 137 mg/kg) content in the final composting material. The principal component analysis showed that the dynamics of dominant genera related to Halomonas, Pusillimonas, and Pseudofulvimonas, all of which were known as nitrifying and denitrifying bacteria, was significantly correlated with the dynamic of NO2− and NO3− content throughout the composting process. The genera related to Pusillimonas, and Pseudofulvimonas appeared as the dominant communities as the NO2− and NO3− increased. In contrast, as the NO2− and NO3− concentration decreased, the Halomonas genus were notably enriched in biochar compost. This study revealed the bacterial community shifts corresponded with the change of physicochemical properties, which provides essential information for a better understanding of monitoring and improving the composting process.

22700. 题目: Variations in CH4 and CO2 productions and emissions driven by pollution sources in municipal sewers: An assessment of the role of dissolved organic matter components and microbiota
文章编号: N20040102
期刊: Environmental Pollution
作者: Hao Chen, Jianfeng Ye, Yafei Zhou, Zhongning Wang, Qilong Jia, Yunhan Nie, Lei Li, Hui Liu, Gaboury Benoit
更新时间: 2020-04-01
摘要: Variations in methane (CH4) and carbon dioxide (CO2) emissions in municipal sewer driven by pollution sources are complex and multifaceted. It is important to investigate the role of dissolved organic matter (DOM) components and microbiota to better understand what and how those variations occurred. For this purpose, this study provides a systematic assessment based on short-term in-sewer conditioned cultivations, in conjunction with a field survey in four typical sewers in Shanghai Megacity. The results are as follows: (1) Sediment plays a main role in driving the sewer carbon emission behavior owing to its strong associations with the utilized substrates and predominant microbes that significantly promoted the gas fluxes (genera Bacteroidete_vadinHA17, Candidatus_competibacter, and Methanospirillum). (2) Aquatic DOM in overlying water is an indispensable factor in promoting total carbon emissions, yet the dominant microbes present there inversely correlated with gas fluxes (genera Methanothermobacter and Bacteroides). (3) The total fluxes of both CH4 and CO2 enhanced by pavement runoff were limited. Its high COD-CH4/CO2 conversion efficiencies can be ascribed to its dominant anthropogenic humic-like components and the emerged aquatic tyrosine-like components. (4) Domestic sewage can significantly enhance the total fluxes because of its high concentration of bioavailable DOM. However, these substrates, which were more suitable for supporting microbial growth, as well as the substrate competition caused by sulfate reduction and the nitrogen cycle (revealed by the dominant functional microbes genera Acinetobacter, Pseudomonas, Dechloromona, and Candidatus_competibacter and their correlations with indicators), seemed to be responsible for the low COD-CH4/CO2 conversion efficiencies of domestic sewage. (5) A field survey indicated the distinct features of carbon emissions of sewer sewage discharged from different catchments. An extreme hydraulic condition in a sewer in the absence of influent showed unexpectedly high levels of CO2, while a small amount of CH4 emissions.