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23401. 题目: Influence of laccase treatment on fouling layer formation in ultrafiltration of birch hot-water extract
文章编号: N20012701
期刊: Separation and Purification Technology
作者: Tiina Virtanen, Jussi Lahti, Anna Kalliola, Tarja Tamminen, Mika Mänttäri, Mari Kallioinen
更新时间: 2020-01-27
摘要: Fouling problems caused by lignin have been limiting the use of membranes in the recovery of value-added materials from biorefinery streams. Fortunately, laccase-based catalytic pretreatments enable modification of lignin to the less fouling form. Because the mechanisms behind the fouling caused by ligneous compounds in wood-based streams are still not deeply understood, the aim of this study was to find out how laccase oxidation affects membrane fouling caused by pressurized hot-water extract. The effect of laccase on the fouling tendency of birch extract was explored both with adsorptive and pressure-driven experiments. The results suggested that laccase treatment increased the molar mass of lignin and improved significantly filtration capacity of commercial polyethersulphone membrane, possibly due to formation of less dense foulant layer during the filtration. Based on FTIR and BET results laccase oxidation decreased both adsorptive and pressure-driven fouling caused by lignin. However, decreases in pure water permeabilities were higher for the samples that were fouled with laccase treated extract. This may have originated from the transformation in the fouling mechanism from the pore narrowing to the pore blocking and could be prevented by the selection of a membrane with a different pore size.
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23402. 题目: Remediation of organic arsenic contaminants with heterogeneous Fenton process mediated by SiO 2 -coated nano zero-valent iron
文章编号: N20012607
期刊: Environmental Science and Pollution Research
作者: Yuancai Lv, Siyi Huang, Guofu Huang, Yifan Liu, Guifang Yang, Chunxiang Lin, Gao Xiao, Yonghao Wang, Minghua Liu
更新时间: 2020-01-26
摘要: Given their considerable solubility in water and potentially high toxicity to human health, organoarsenic compounds have become an emerging contaminant. Herein, a heterogeneous Fenton process mediated by SiO₂-coated nano zero-valent iron (SiO₂-nZVI) was employed to simultaneously remove the p-arsanilic acid (p-ASA, a typical organoarsenic compound) and the released arsenic. The initial pH value significantly influenced on the degradation of p-ASA and at the optimal pH (3.0), p-ASA (10 mg L⁻¹) could be completely oxidized to As(V), NH₄⁺, and plentiful phenolic compounds such as phenol and p-hydroquinone via the cleavage of C–N and C–As bonds within 60 min in pure water. Meanwhile, although the formed lepidocrocite and magnetite on the surface of SiO₂-nZVI significantly limited the reutilization, they played a vital role in the adsorption of the released As(V) and the residual arsenic levels in the effluent were as low as 0.031 mg L⁻¹, meeting both the drinking water standard of the World Health Organization (WHO) and the surface water standard of China (0.05 mg L⁻¹). Furthermore, high-level dissolved organic matters (DOM) (> 2 mg C L⁻¹) exhibited strong interference with both the oxidation of p-ASA and adsorption of arsenic, but the interference could be eliminated by increasing the SiO₂-nZVI dosage or adding H₂O₂. Importantly, this system could completely remediate p-ASA in a short time and simultaneously avoid the secondary pollution caused by inorganic arsenic, which was significant for the remediation of organoarsenic pollutants in swine wastewater.

23403. 题目: Effect of Biochar and Coal Fly Ash Soil Amendments on the Leaching Loss of Phosphorus in Subtropical Sandy Ultisols
文章编号: N20012606
期刊: Water, Air, & Soil Pollution
作者: Nadeesha L. Ukwattage, Yuncong Li, Yandong Gan, Tiantian Li, Ranjith P. Gamage
更新时间: 2020-01-26
摘要: Leaching of phosphorus fertilizer from loose-structured subtropical soils is a major course of agricultural water pollution in southeastern USA. Soil amendments play a major role in the phosphorus retention in soil through different mechanisms. In the present study we tested the effect of two soil amendments; biochar and coal fly ash in immobilizing the soluble phosphorus fertilizer added to sandy Ultisol soils from subtropical USA. Column leaching tests were conducted with Ultisol soil added with biochar (from avocado branch cut biomass) and coal fly ash at 5 tons/ha rate, under simulated rainfall, to collect the leachate over five pore volumes. The leachate was analyzed for the phosphate phosphorus content. In the end, the soil columns were carefully extracted, sectioned and analyzed for the total phosphorus, after acid digestion. Results showed 50% and 6% drop of soluble phosphorus leaching loss in biochar and coal fly ash added soil respectively. Soil amendments have shifted the loosely bound phosphorus into the Ca/Mg bound and Al/Fe/Mn bound pools which are not readily water extractable. Addition of biochar and coal fly ash together showed a synergistic interaction effect in reducing the leaching loss of phosphorus which needs further investigation to understand the exact mechanism.

23404. 题目: Sensitivity analysis of agricultural inputs for large-scale soil organic matter modelling
文章编号: N20012605
期刊: Geoderma
作者: Julius Diel, Uwe Franko
更新时间: 2020-01-26
摘要: The dynamics of Soil Organic Matter (SOM) and its relation to the carbon and nitrogen cycle affect many environmental problems (e.g. climate change, food security and water quality). The development of adaptation strategies requires model predictions, but for the necessary large-scale SOM dynamic studies, the quality of the input data is often limiting the reliability of the results.So we performed a uncertainty and sensitivity analysis at different sites of the federal state of Saxony, Germany, and assessed the importance of aggregated agricultural data, namely organic amendments, crop yields, area share of by-product incorporation, area share of conservation tillage and initial soil organic carbon (SOC) concentration (p_oram, p_yield, p_bp, p_cons and p_soc respectively) on the result uncertainty by assuming an uniform error of ±10%. The agricultural data was regionalized from 717 long-term observation fields throughout the study region.We assessed the uncertainties of relative SOC stock change (ΔC_rel) and total nitrogen mineralisation from the organic matter (OM-N_min) and explored the changing sensitivities over the model period (1998–2014).Our results show that p_soc was the most important source of uncertainty for all sites of this study. For ΔC_rel, it is over the whole time constantly the by far most sensitive input parameter, with p_bp being the only factor of agricultural practice with some substantial influence on almost all sites. In the mountainous regions, p_cons ranks equal to p_bp, while for the sandy heathlands, none of them mark a substantial influence besides p_soc.For OM-N_min, p_soc loses its importance over time, being outranked by p_oram in the heathlands after 8 years and in the mountainous regions after 13 years. p_oram furthermore places second for all others but one other region, where p_cons is slightly more important. We therefore see the initial carbon content, the share of by-product removal, and the amount of organic amendments as those factors, where improved data quality would bring the highest effect to reduce the uncertainty in regional SOM modelling.

23405. 题目: Dynamic variation in nitrogen removal of constructed wetlands modified by biochar for treating secondary livestock effluent under varying oxygen supplying conditions
文章编号: N20012604
期刊: Journal of Environmental Management
作者: Likui Feng, Yang Liu, Jinyong Zhang, Cong Li, Haiming Wu
更新时间: 2020-01-26
摘要: Vertical flow constructed wetlands are facing the problem of low removal efficiency when treating high-load wastewater. This study explored the effect of oxygen supplement (1.2, 1.0, 0.8 L min⁻¹ for 6 h; 1.0 L min⁻¹ for 4 h and 2 h) on enhancing nitrogen removal in vertical flow constructed wetlands modified by adding biochar for treating secondary livestock effluent. The results indicated that biochar addition could enhance contaminant removal due to its adsorption of contaminants under the condition of no aeration. Additionally, the aeration addition of 1.0 L min⁻¹ for 2 h per day in biochar-based constructed wetlands achieved the high efficiencies for chemical oxygen demand (95%) and total nitrogen (73%) removal. However, total nitrogen removal efficiency in biochar-based constructed wetlands declined under excessive dissolved oxygen conditions which might restrain the denitrification process. Average nitrous oxide emission fluxes in biochar-based constructed wetlands (575–1877 μg m⁻² h⁻¹) were lower than those in non-biochar constructed wetlands (745–2298 μg m⁻² h⁻¹). In addition, the variation of N₂O emission under different aeration conditions was similar with the maximum value at the aeration condition of 1.2 L min⁻¹ for 6 h d⁻¹. These results could be useful for improving the sustainable design and operation of constructed wetlands for high-load wastewater treatments.
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23406. 题目: Mobility monitoring of two herbicides in amended soils: A field study for modeling applications
文章编号: N20012603
期刊: Journal of Environmental Management
作者: María J. Carpio, M. Sonia Rodríguez-Cruz, Carlos García-Delgado, María J. Sánchez-Martín, Jesús M. Marín-Benito
更新时间: 2020-01-26
摘要: This paper reports the mobility and total balance of chlorotoluron (CTL), flufenacet (FNC) and bromide ion (Br⁻) throughout a sandy soil profile after the application of spent mushroom substrate (SMS) and green compost (GC). Obtaining mobility dataset is crucial to simulate the herbicides' fate under amended soil scenarios by application pesticide leaching models with regulatory application (FOCUS models). The application of organic residues is nowadays increased to improve the crop yields and there is a gap in the simulations of this kind of amended scenarios. A two-year field experiment involving unamended soil (S) and SMS- or GC-amended soil plots was conducted. CTL, FNC, and Br⁻ were annually applied and their residual concentrations were determined in soil profiles (0–100 cm) regularly sampled. In all the treatments the order of mobility is followed as FNC < CTL < Br⁻. SMS and GC increased herbicide retention in the top 10 cm by the higher organic carbon (OC) content than the unamended soil, and their ability to increase the soil's water-holding capacity and to decrease water percolation. Simultaneously dissolved organic carbon (DOC) content facilitated herbicide transport being it favoured by the initial soil moisture content and the rainfall shortly after the chemicals' initial application. Over the first year, residual amounts (<2.6%) of Br⁻, CTL and FNC were leached down to 90–100 cm depth in the three treatments. However, over the second year low CTL and FNC amounts (<1.0%) reached the bottom layer only in S + SMS although high Br⁻ concentrations did so in the three treatments (<20%). According to the total balance of Br⁻, CTL, and FNC in the soil profiles other processes (degradation, mineralisation, bound residues formation, and/or crop uptake) different from leaching below 1 m depth might play a key role in their dissipation especially in the amended soil profiles. SMS and GC are likely to be used as organic amendments to preserve the soil and water quality but in the case of SMS, its higher DOC content could imply a higher potential risk for groundwater contamination than GC.

23407. 题目: How do earthworms affect organic matter decomposition in the presence of clay-sized minerals?
文章编号: N20012602
期刊: Soil Biology and Biochemistry
作者: J. Barthod, M.-F. Dignac, G. Le Mer, N. Bottinelli, F. Watteau, I. Kögel-Knabner, C. Rumpel
更新时间: 2020-01-26
摘要: Clay-sized soil minerals are known to protect organic carbon (OC) from mineralisation by formation of organo-mineral associations limiting its availability to microorganisms. The impact of soil fauna on these processes is poorly known. The aim of this study was to investigate the effect of earthworms on organic matter (OM) decomposition and association with minerals during a laboratory experiment. We used a model system consisting of fresh OM incubated with and without epigeic earthworms (Eisenia andrei and foetida) in presence of different types and amounts of phyllosilicates (kaolinite, montmorillonite) and an iron oxide (goethite) and combinations of these minerals. Our experimental setup included a high OM:mineral ratio to represent the soil-litter interphase. We monitored OC mineralization during 196 days. Additionally, we investigated physicochemical parameters and chemical OM characteristics of decomposition products by determination of water-soluble OC (WSOC) and acquisition of solid-state ¹³C NMR spectra. We also analysed microscale organisation of the organo-mineral associations produced with and without earthworms by transmission electron microscopy (TEM).Earthworms enhanced OC mineralisation in all treatments. They also led to greater reductions of OC emissions in the presence of minerals as compared to the mineral-free control, depending on the type and amount of minerals added. The presence of earthworms affected microbial biomass, the concentration of WSOC and increased the contribution of aromatic compounds to OM decomposition products. Microscale analyses by TEM showed that earthworms favoured association of minerals with partly degraded OM along with completely degraded material, while in absence of earthworms only completely degraded OM was associated with minerals. We conclude that earthworms impact OM decomposition through (1) their effect on microbial biomass and the physicochemical parameters of microbial habitat and (2) the formation of OM associations by changing the OM types associated to minerals and possibly by creating closer association of partly degraded OM and iron oxides. The stability of these associations remains to be investigated.

23408. 题目: Nitrogen dynamics affected by biochar and irrigation level in an onion field
文章编号: N20012601
期刊: Science of The Total Environment
作者: Suduan Gao, Dong Wang, Sadikshya R. Dangi, Yinghua Duan, Tom Pflaum, Jim Gartung, Ruijun Qin, Thomas Turini
更新时间: 2020-01-26
摘要: Soil amended with biochar has many potential environmental benefits, but its influence on the fate of nitrogen (N) under irrigated conditions is unclear. The objective of this research was to determine the effects of biochar and interactions with irrigation on N movement in soil, gas emissions, and leaching. A three-year study was conducted in an onion field with three main irrigation treatments (50, 75, and 100% of a reference that provided sufficient water for plant growth) and three biochar amendment rates (0 or control, low char - applied first year at 29 Mg ha⁻¹, and high char - added both first and second year for a total 58 Mg ha⁻¹) as sub-treatments in a split-plot design. Nitrogen fertilizer was applied three times during first year growing season, but weekly the second year. Ammonia (NH₃) volatilization, nitrous oxide (N₂O) emission, and nitrate (NO₃⁻) in soil pore water were monitored during growing season, and annual N (total and NO₃⁻) changes in soil profile were determined for first two years. Nitrate leaching was measured in the third year. Ammonia volatilization was affected by fertilization frequency with higher loss (5–8% of total applied) when fertilizer was applied in large doses during the first year compared to the second year (4–5%). Nitrous oxide emissions were ≤0.1% of applied N for both years and not affected by any treatments or fertilization frequency. Nitrate concentration in soil profile increased significantly as irrigation level dropped, but most of the NO₃⁻ was leached by winter rain. There was no significant biochar effect on total N gas emissions or soil NO₃⁻ accumulation, but significant irrigation effect and interaction with biochar were determined on soil NO₃⁻ accumulation. High leaching was associated with biochar amendment and higher irrigation level. Irrigation strategies are the key to improving N management and developing the best practices associated with biochar.
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23409. 题目: Fluorescence characteristics of particulate water-soluble Organic Compounds Emitted from coal-fired boilers
文章编号: N20012516
期刊: Atmospheric Environment
作者: Yanrong Yang, Juanjuan Qin, Ting Qi, Xueming Zhou, Rongzhi Chen, Jihua Tan, Kang Xiao, Dongsheng Ji, Kebin He, Xiaoting Chen
更新时间: 2020-01-25
摘要: The fluorescence characteristics of particulate water-soluble organic compounds (WSOC) emitted by different power of coal-fired boilers (A total of 14 boilers including 1, 2, 4, 6, 10, 15, 20 tons steam per hour (t·h−1)) in Lanzhou, an industrial city of northwest China, were analyzed by excitation-emission matrix (EEM) fluorescence spectroscopy. Results showed that the fluorescence profiles of WSOC in different power coal-fired boiler samples had certain similarities, reflecting the consistency of the fluorophore structures in the coal-originated WSOC. In general, the main excitation (Ex) and emission (Em) wavelength ranges of fluorescence peaks generated by WSOC were λEx = 230–250 nm and λEm = 360–430 nm. Since the fluorophore of WSOC was mainly concentrated in the fluorescent regions II and III, the main components in the fluorophore were tryptophan-like, fulvic acid and humic-like substances. Humification index (HIX), fluorescence index (FI) and freshness index (BIX) were 0.36 ± 0.36, 2.09 ± 0.42 and 1.02 ± 0.30, respectively. It may indicate that the particulate WSOC had a lower degree of humification and lower aromaticity. In the range of larger Stokes shift (λEx−1-λEm−1 ≥ 1.2 μm−1), the normalized fluorescence intensity of WSOC showed the largest peak, suggesting that there may be many hydrophobic substances containing a large number of π-conjugated systems in WSOC. These findings are not only conducive to cognize the optical characteristics of particulate matter emitted from coal-fired pollution sources, but also help to consummate the spectral characteristics of coal-fired pollution sources.

23410. 题目: Unrecognized Contributions of Dissolved Organic Matter Inducing Photodamages to the Decay of Extracellular DNA in Waters
文章编号: N20012515
期刊: Environmental Science & Technology
作者: Xin Zhang, Jing Li, Mu-Cen Yao, Wen-Yuan Fan, Chuan-Wang Yang, Li Yuan, Guo-Ping Sheng
更新时间: 2020-01-25
摘要: Extracellular DNA (eDNA), which is derived from lysis or secretion of cells, is ubiquitous in various environments and crucial for gene dissemination, bacterial metabolism, biofilm integrity, and aquatic monitoring. However, these processes are largely influenced by damage to eDNA. Photodamage to eDNA, one of the most important types of DNA damage in natural waters, thus far remains unclear. In particular, the roles of the ubiquitous dissolved organic matter (DOM) in this process have yet to be determined. In this study, eDNA photodamage, including both deoxynucleoside damage and strand breaks, proved to be significantly influenced by DOM. DOM competed with eDNA for photons to inhibit the direct photodamage of eDNA. Nevertheless, DOM was photosensitized to produce reactive oxygen species (ROS) (i.e., hydroxyl radicals (·OH) and singlet oxygen (1O2)) to enhance the indirect photodamage of eDNA. The ·OH induced damage to four deoxynucleosides and strand breaks, and the 1O2 substantially enhanced deoxyguanosine damage. The presence of DOM changed the main photodamage products of deoxynucleosides, additional oxidation products induced by ROS formed besides pyrimidine dimers caused by UV. Results indicate that DOM-mediated indirect photodamage contributed significantly to eDNA photodamage in most water bodies. This study revealed the previously unrecognized crucial role of DOM in the decay of eDNA in waters.

23411. 题目: Paleo-environmental evidence of ecosystem change in Lake St. Clair region of Laurentian Great Lakes basin: contrasting responses to land-use change and invasive mussels
文章编号: N20012514
期刊: Journal of Paleolimnology
作者: Melissa M. Baustian, Yolanda M. Brooks, Mark Baskaran, Peter R. Leavitt, Bo Liu, Nathaniel Ostrom, R. Jan Stevenson, Joan B. Rose
更新时间: 2020-01-25
摘要: The Laurentian Great Lakes have been subject to substantial modification from diverse anthropogenic stressors, including nutrient enrichment, climate change, chemical and biological pollutants, and invasive species, yet little is known of the relative historical influence of these factors. Here we analyze diverse fossil metrics from vibracores at two sites, a bay area (Anchor Bay) and a tributary (Clinton River) in the Lake St. Clair ecosystem to determine the ecological responses from land-use practices and invasive mussel invasions. Sediment cores spanning over 100 years indicated that the expansion of non-native Dreissena polymorpha and Dreissena rostriformis (dreissenid mussels) into Anchor Bay site after the mid-1990s was associated with ~ 60 to 95% reduction in algal and cyanobacterial abundances and twofold increase in sedimentary organic matter (SOM) and bioavailable phosphorus. These increases in SOM and bioavailable phosphorus are relatively similar to increases inferred from the late nineteenth century when large portions of the watershed were cleared and drained for agriculture. In contrast, the Clinton River site experienced a continuous increase in the influx of nutrients, organic matter, and elevated sedimentary phototrophic pigments during the twentieth century and into the twenty-first century. Site comparisons suggest different mechanisms inducing changes in primary production varied, where Anchor Bay was mainly affected by the comparatively recent (since ca. mid-1990s) endogenous influence of invasive species, while the Clinton River site was primarily influenced by the input of exogenous anthropogenic nutrients over the past 100 years. These new findings illustrate that watershed management and policies within large lakes with multi-jurisdictional (national) Area of Concerns should consider site-specific regulatory mechanisms.

23412. 题目: Different carboxyl‐rich alicyclic molecules proxy compounds select distinct bacterioplankton for oxidation of dissolved organic matter in the mesopelagic Sargasso Sea
文章编号: N20012513
期刊: Limnology and Oceanography
作者: Shuting Liu, Rachel Parsons, Keri Opalk, Nicholas Baetge, Stephen Giovannoni, Luis M. Bolaños, Elizabeth B. Kujawinski, Krista Longnecker, YueHan Lu, Elisa Halewood, Craig A. Carlson
更新时间: 2020-01-25
摘要: Marine dissolved organic matter (DOM) varies in its recalcitrance to rapid microbial degradation. DOM of varying recalcitrance can be exported from the ocean surface to depth by subduction or convective mixing and oxidized over months to decades in deeper seawater. Carboxyl‐rich alicyclic molecules (CRAM) are characterized as a major component of recalcitrant DOM throughout the oceanic water column. The oxidation of CRAM‐like compounds may depend on specific bacterioplankton lineages with oxidative enzymes capable of catabolizing complex molecular structures like long‐chain aliphatics, cyclic alkanes, and carboxylic acids. To investigate the interaction between bacteria and CRAM‐like compounds, we conducted microbial remineralization experiments using several compounds rich in carboxyl groups and/or alicyclic rings, including deoxycholate, humic acid, lignin, and benzoic acid, as proxies for CRAM. Mesopelagic seawater (200 m) from the northwest Sargasso Sea was used as media and inoculum and incubated over 28 d. All amendments demonstrated significant DOC removal (2–11 μmol C L⁻¹) compared to controls. Bacterioplankton abundance increased significantly in the deoxycholate and benzoic acid treatments relative to controls, with fast‐growing Spongiibacteracea, Euryarcheaota, and slow‐growing SAR11 enriched in the deoxycholate treatment and fast‐growing Alteromonas, Euryarcheaota, and Thaumarcheaota enriched in the benzoic acid treatment. In contrast, bacterioplankton grew slower in the lignin and humic acid treatments, with oligotrophic SAR202 becoming significantly enriched in the lignin treatment. Our results indicate that the character of the CRAM proxy compounds resulted in distinct bacterioplankton removal rates of DOM and affected specific lineages of bacterioplankton capable of responding.

23413. 题目: Bacterioplankton metabolism of phytoplankton lysates across a cyclone‐anticyclone eddy dipole impacts the cycling of semi‐labile organic matter in the photic zone
文章编号: N20012512
期刊: Limnology and Oceanography
作者: Emma K. Wear, Craig A. Carlson, Matthew J. Church
更新时间: 2020-01-25
摘要: Mesoscale eddies, prominent physical processes in the stratified ocean gyres, affect community composition and metabolic rates of both phytoplankton and heterotrophic bacterioplankton (free‐living bacterial and archaeal) communities. We hypothesized that in situ differences in organic matter production would predispose bacterioplankton communities from cyclonic vs. anticyclonic eddies toward metabolic capabilities better suited to utilizing dissolved organic matter (DOM) from the phytoplankton groups commonly associated with each eddy polarity. To test this, we established dilution batch‐culture bioassay incubations along a cyclone to anticyclone spatial transect in the North Pacific Subtropical Gyre. Unamended incubations, to assess spatial variability in ambient DOM bioavailability, and incubations amended with lysates of phytoplankton cultures were established and community growth and metabolic responses were assessed. Over timescales of days, lysate type was more influential than incubation origin: Prochlorococcus lysate was rapidly remineralized, while Emiliania huxleyi lysate was efficiently incorporated into biomass and developed a unique community of copiotrophic bacteria. Over timescales of 1 week to 1 month, eddy effects were indirectly apparent in their potential to promote metabolic processes related to DOM production and consumption. Surface lysate incubations showed priming of ambient DOM, that is, the remineralization of DOM, which was otherwise not bioavailable, in the presence of labile substrates. Some incubations originating from the deep chlorophyll maximum demonstrated signatures of chemoautotrophy fueled by nitrification, coincident with eddy‐driven isopycnal uplift. We conclude that eddy polarity itself does not determine community‐level bacterioplankton metabolic capabilities; however, mesoscale processes may indirectly affect slower, semi‐labile organic matter processing in the oligotrophic ocean.

23414. 题目: Seasonality of Organic Matter Degradation regulates Nutrient and Metal Net Fluxes in a High Energy Sandy Beach
文章编号: N20012511
期刊: Journal of Geophysical Research: Biogeosciences
作者: Janis Ahrens, Melanie Beck, Hannah Marchant, Soeren Ahmerkamp, Bernhard Schnetger, Hans‐Jürgen Brumsack
更新时间: 2020-01-25
摘要: During seawater circulation in permeable intertidal sands, organic matter degradation alters the composition of percolating fluids and remineralization products discharge into surficial waters. Concurrently, coastal seawater nutrient and organic matter composition change seasonally due to variations in pelagic productivity. To assess seasonal changes in organic matter degradation in the intertidal zone of a high energy beach (Spiekeroog Island, southern North Sea, Germany), we analyzed shallow pore waters for major redox constituents (oxygen (O₂), manganese (Mn), iron (Fe)) and inorganic nitrogen species (nitrite (NO₂^‐), nitrate (NO₃^‐), ammonium (NH₄⁺)) in March, August, and October. Surface water samples from a local time series station were used to monitor seasonal changes in pelagic productivity. O₂ and NO₃^‐ were the dominating pore water constituents in March and October. Dissolved Mn, Fe, and NH₄⁺ were more widely distributed in August. Seasonal changes in seawater temperature as well as organic matter and nitrate supply by seawater were assumed to affect microbial rates and degradation pathways. Pore water and seawater variability led to seasonally changing constituent effluxes to surface waters. Mn, Fe, and NH₄⁺ effluxes are minimal in March and reached their maximum in August. Furthermore, the intertidal sands switched from a net dissolved inorganic nitrogen (DIN) sink in March to a net source in August. In conclusion, seasonal effects on intertidal pore water biogeochemistry affect constituent fluxes across the sediment‐water interface. The seasonality of the beach bioreactor must be considered when fluxes are extrapolated to annual timescales.

23415. 题目: Tillage intensity reduces the arbuscular mycorrhizal fungi attributes associated with Solanum lycopersicum, in the Tehuantepec Isthmus (Oaxaca), Mexico
文章编号: N20012510
期刊: Applied Soil Ecology
作者: Ángel Vivani de la Cruz-Ortiz, Jonás Álvarez-Lopeztello, Celerino Robles, Laura V. Hernández-Cuevas
更新时间: 2020-01-25
摘要: Understanding the responses of arbuscular mycorrhizal fungi (AMF) attributes and soil properties to tillage intensity is useful for the management of agroecosystems, especially in tropical lands, which are under intense pressures for human activities. This study aimed to examine the AMF attributes such as spore-based species richness, spore density, and root mycorrhizal colonization in systems with different tillage practices (intensive, traditional, and conservation). The soil of the study systems were sandy loam, moderately alkaline, and showed low levels of inorganic nitrogen and available phosphorus. Conservation tillage displayed the lowest pH and the highest inorganic nitrogen, soil organic carbon, and soil organic matter levels. Traditional tillage showed the lowest available phosphorus concentrations and the highest electric conductivity levels. Conservation tillage system showed the highest AMF spore-based species richness, spore density, and root mycorrhizal colonization; in contrast to intensive tillage that showed the lowest values. Spore density was not affected by the tillage intensity. Spore density and root mycorrhizal colonization appeared to increase with low available phosphorus levels. Spore density seemed to decrease as the levels of soil organic carbon and sand increased; by the contrary, root mycorrhizal colonization appeared to increase with high soil organic carbon levels, and decreased as the levels of inorganic nitrogen increased. This study highlights the conservation tillage as a useful management tool for maintaining the AMF attributes and soil properties.

23416. 题目: Selective carbon sources and salinities enhance enzymes and extracellular polymeric substances extrusion of Chlorella sp. for potential co-metabolism
文章编号: N20012509
期刊: Bioresource Technology
作者: Hoang Nhat Phong Vo, Huu Hao Ngo, Wenshan Guo, Yiwen Liu, Soon Woong Chang, Dinh Duc Nguyen, Xinbo Zhang, Heng Liang, Shan Xue
更新时间: 2020-01-25
摘要: This study investigated the extracellular polymeric substance (EPS) and enzyme extrusion of Chlorella sp. using seven carbon sources and two salinities for potential pollutant co-metabolism. Results indicated that the levels of biomass, EPS and enzymes of microalgae cultured with glucose and saccharose outcompeted other carbon sources. For pigment production, glycine received the highest chlorophyll and carotene, up to 10 mg/L. The EPS reached 30 mg/L, having doubled the amount of protein than carbohydrate. For superoxide dismutase and peroxidase enzymes, the highest concentrations were beyond 60 U/ml and 6 nmol/d.ml, respectively. This amount could be potentially used for degrading 40% ciprofloxacin of concentration 2000 µg/L. When increasing salinity from 0.1% to 3.5%, the concentrations of pigment, EPS and enzymes rose 3 to 30 times. These results highlighted that certain carbon sources and salinities could induce Chlorella sp. to produce EPS and enzymes for pollutant co-metabolism and also for revenue-raising potential.
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23417. 题目: Roles of biochar media and oxygen supply strategies in treatment performance, greenhouse gas emissions, and bacterial community features of subsurface-flow constructed wetlands
文章编号: N20012508
期刊: Bioresource Technology
作者: Bohua Ji, Jinquan Chen, Jian Mei, Junjun Chang, Xuan Li, Wei Jia, Ying Qu
更新时间: 2020-01-25
摘要: Biochar-based subsurface-flow constructed wetlands (CWs) with intermittent aeration (IA) or tidal flow (TF) oxygen supply strategies were established to treat domestic wastewater. The results showed that biochar achieved higher nutrient removal and lower greenhouse gas (GHG) emissions than ceramsite while supporting more diverse bacterial communities and higher abundances of functional taxa. Both IA and TF effectively enhanced nutrient removal, though the latter was more efficient and practical, and aeration conditions greatly influenced nutrient removal efficiency. GHG emissions were decreased by IA but were slightly increased by TF. Both oxygen supply methods significantly shaped the biofilm microbial communities and influenced biodiversity and richness, with observably higher proportions of potential nitrifiers and denitrifiers present in aerated CWs. Overall, biochar-based CWs operated with oxygen supply strategies provide superior treatment of decentralized wastewater.
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23418. 题目: Methane yield enhancement of mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste using algal biochar: Semi-continuous operation and microbial community analysis
文章编号: N20012507
期刊: Bioresource Technology
作者: Le Zhang, Fanghua Li, Agnès Kuroki, Kai-Chee Loh, Chi-Hwa Wang, Yanjun Dai, Yen Wah Tong
更新时间: 2020-01-25
摘要: The impact of algal biochar addition on mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste was investigated with a focus on semi-continuous operations and functional microbial communities. Under batch co-digestion, the highest co-digestion synergy was observed for a mixture of 25% food waste and 75% algal biomass. During semi-continuous co-digestion of 25% food waste-75% algal biomass mixture, biochar amended digesters exhibited a 12-54% increase in average methane yield (275.8-394.6 mL/gVS) compared to the controls. Elevated temperature induced narrow distributions of volatile fatty acids (VFAs) by inhibiting the production of branched VFAs. Genus Proteiniphilum was selectively enriched by 3.2 folds in mesophilic digesters with biochar amendment while genus Defluviitoga was selectively enriched in thermophilic digesters due to elevated temperature. Methanogenic communities were significantly different in mesophilic and thermophilic digesters. Biochar amendment contributed to shifts in the predominant methanogens leading to a more balanced state of two methanogenic pathways.
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23419. 题目: Optical properties of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) levels in constructed water treatment wetland systems in southern California, USA
文章编号: N20012506
期刊: Chemosphere
作者: Catherine D. Clark, Warren J. De Bruyn, Benjamin Brahm, Paige Aiona
更新时间: 2020-01-25
摘要: Many removal mechanisms in treatment wetlands involve absorption to organic matter. Optical properties and DOC levels of waters entering and exiting 4 treatment wetland systems in Orange County, Southern California, were measured to characterize the dissolved organic matter pool. Average DOC levels decreased between the inlets and outlets, except for Forge Street (FS), which increased. For 3 wetlands, absorption coefficients decreased between inlet and outlet; the exception was FS, which increased. Average spectral slopes for the inlets and outlets were similar. Average intensities of terrestrial humic peaks A and C from 3D EEM fluorescence spectra decreased between the inlets and outlets for most wetlands. No EEM protein peaks were observed. Average flu/abs ratios for inlets and outlets were similar (high point for FS inlet excluded), suggesting chromophoric dissolved organic matter (CDOM) of a similar composition was present. The average FI value for the inlets and outlets was ∼1.5, consistent with terrestrial sources of CDOM. Average BIX values for the inlets and outlets were ∼0.8, suggesting limited contributions from autochthonous production of CDOM. Dominant plant species in the wetlands were cattail and bulrush. Humic peaks A and C, along with protein peaks, were observed in plant leachates. Protein peaks rapidly degraded with solar simulator irradiation. Results indicate that most of the wetlands are a net sink for CDOM, possibly due to absorption to sediments. The FS wetland appears to have a source of non-CDOM optically active organic carbon, possibly from a pollutant.

23420. 题目: Substrate availability and soil microbes drive temperature sensitivity of soil organic carbon mineralization to warming along an elevation gradient in subtropical Asia
文章编号: N20012505
期刊: Geoderma
作者: Xiaojie Li, Jinsheng Xie, Qiufang Zhang, Maokui Lyu, Xiaoling Xiong, Xiaofei Liu, Tengchiu Lin, Yusheng Yang
更新时间: 2020-01-25
摘要: Subtropical forest soil exerts a large, but uncertain effect on terrestrial carbon (C) cycling. Global warming is anticipated to alter subtropical soil C cycling but currently, there is no consensus on how warming will affect soil C at different elevations. We conducted a short-term laboratory soil warming incubation experiment (ambient temperature +4 °C) along an elevational gradient in Wuyi Mountains of southeastern China to examine the response of soil organic carbon (SOC) mineralization to rising temperatures. Soil samples were collected from three elevations (630 m, 1450 m and 2130 m), and microbial community composition was determined using phospholipid fatty acids (PLFAs). The SOC mineralization increased with rising mean annual temperature (i.e., with decreasing elevation) and with experimental warming. Unlike most other similar experimental studies, we found that the temperature sensitivity (Q₁₀) of SOC mineralization to short-term experimental warming significantly decreased with increasing elevation. We also found that temperature sensitivity of SOC mineralization in response to warming depends on substrate availability, as indicated by the significant relationship between dissolved organic carbon (DOC) and Q₁₀ values. In addition, soil microbial biomass increased significantly with increasing elevations, but was not significantly affected by short-term experimental warming. Experimental warming reduced the abundance of total PLFAs, bacteria, fungi, and actinomycetes in the low-elevation soil. Experimental warming significantly changed soil microbial community composition at low elevation, with increases in the ratios of cyclopropyl to monoenoic precursor fatty acids (cy:pre), saturated to monounsaturated fatty acids (sat:mono), and isomers to trans-isomers fatty acids (i:a), all of which are stress indicators, indicating that warming treatment increased microbial respiration rather than microbial growth, because the microbial respiration per biomass increases under environmental stress. Microorganisms likely altered their membrane fatty acid components and mass in response to changes in available C. The differences in Q₁₀ associated with short-term warming and among elevations with long-term temperature differences indicate that the effect of warming on SOC mineralization may change through time and this should be taken into account when predicting SOC mineralization in response to continual rising temperatures.