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14181. 题目: High variability of particulate organic carbon export along the North Atlantic GEOTRACES section GA01 as deduced from 234Th fluxes
文章编号: N18110203
期刊: Biogeosciences
作者: Nolwenn Lemaitre, Frédéric Planchon, Hélène Planquette, Frank Dehairs, Debany Fonseca-Batista, Arnout Roukaerts, Florian Deman, Yi Tang, Clarisse Mariez, and Géraldine Sarthou
更新时间: 2018-11-02
摘要: In this study we report particulate organic carbon (POC) export fluxes for different biogeochemical basins in the North Atlantic as part of the GEOTRACES GA01 expedition (GEOVIDE, May–June 2014). Surface POC export fluxes were deduced by combining export fluxes of total Thorium-234 (234Th) with the ratio of POC to 234Th of sinking particles at the depth of export. Particles were collected in two size classes ( > 53 and 1–53µm) using in situ pumps and the large size fraction was considered representative of sinking material. Surface POC export fluxes revealed latitudinal variations between provinces, ranging from 1.4mmolm−2d−1 in the Irminger basin, where the bloom was close to its maximum, to 12mmolm−2d−1 near the Iberian Margin, where the bloom had already declined. In addition to the state of progress of the bloom, variations of the POC export fluxes were also related to the phytoplankton size and community structure. In line with previous studies, the presence of coccolithophorids and diatoms appeared to enhance the POC export flux, while the dominance of picophytoplankton cells, such as cyanobacteria, resulted in lower fluxes. The ratio of POC export to primary production (PP) strongly varied regionally and was generally low ( ≤ 14%), except at two stations located near the Iberian Margin (35%) and within the Labrador basin (38%), which were characterized by unusual low in situ PP. We thus conclude that during the GEOVIDE cruise, the North Atlantic was not as efficient in exporting carbon from the surface, as reported earlier by others. Finally, we also estimated the POC export at 100m below the surface export depth to investigate the POC transfer efficiencies. This parameter was also highly variable amongst regions, with the highest transfer efficiency at sites where coccolithophorids dominated.
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14182. 题目: Effects of the interaction between temperature and revegetation on the microbial degradation of soil dissolved organic matter (DOM) – A DOM incubation experiment
文章编号: N18110202
期刊: Geoderma
作者: Hongfei Liu, Yang Wu, Zemin Ai, Jiaoyang Zhang, Chao Zhang, Sha Xue, Guobin Liu
更新时间: 2018-11-02
摘要: DOM is the most bioavailable organic pool in the soil. The restoration of vegetation on abandoned cropland has a major impact on the concentration and composition of the DOM and thus affects the biodegradability of the soil DOM. Understanding the response of the microbial degradation of the DOM to temperature is important to maintain soil bioavailable organic matter in the field. We conducted a laboratory DOM solution incubation experiment to examine the temporal dynamics of DOM concentrations at temperatures of 4 °C (low), 20 °C (medium), and 35 °C (high) for four types of land uses: sloped cropland, grassland, shrub land, and woodland. Ultraviolet–visible and fluorescence spectroscopy were used to determine the structural complexity of the DOM. The conversion of the sloped cropland to shrub land and woodland significantly increased contents of DOC, DON, and recalcitrant substances in DOM soilution, such as humic-like material and fulvic acid, and stabilised the DOC pool, and reduced the decomposition of the DOC at 20 °C and 35 °C. The conversion of the sloped cropland to woodland dramatically reduced TDN decomposition. The DON loss after 60-day incubation significantly correlated with the initial content of tryptophan-like material. The biodegradability of the DON was higher and more sensitive to temperature than that of the DOC. Rising temperature initially promotes the decomposition of tryptophan-like material, and later promotes the degradation of more recalcitrant substances, such as humic-like material and fulvic acid, which enhanced the decomposition of the DOC and DON. The results suggest that the conversion of sloped cropland to shrubland and woodland not only promoted the accumulation of DOC, TDN, and recalcitrant substances in DOM solution, and decreased their biodegradability but also decreased the temperature sensitivity of the decomposition of the DOC and DON. Therefore, shrubland and woodland were the optimal choices for revegetation in the Loess Plateau of China.
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14183. 题目: Increasing soil carbon content with declining soil manganese in temperate rainforests: is there a link to fungal Mn?
文章编号: N18110201
期刊: Soil Biology and Biochemistry
作者: J.M. Kranabetter
更新时间: 2018-11-02
摘要: Forest floor carbon (C) sequestration has been negatively correlated with manganese (Mn) availability, possibly due to reduced efficacy of Mn-peridoxase enzymes produced by Agaricomycete fungi. I examined a soil C and Mn dataset from a podzolization gradient, along with fungal sporocarp Mn concentrations, to potentially corroborate this finding. An inverse power relationship between soil C and soil Mn content across temperate rainforests was confirmed, which provides further evidence of a Mn bottleneck in C turnover. Average Mn concentrations of saprotrophic sporocarps were greater than those of ectomycorrhizal fungi, and displayed a similar inverse correlation with increasing soil C. The absence or limited effectiveness of select saprotrophic fungi across Mn-depleted forest soils may be one mechanism behind impeded turnover of recalcitrant organic matter.

14184. 题目: Investigating Fluorescent Organic-Matter Composition as a Key Predictor for Arsenic Mobility in Groundwater Aquifers
文章编号: N18110119
期刊: Environmental Science & Technology
作者: Anna-Ricarda Schittich, Urban J. Wünsch, Harshad V. Kulkarni, Maria Battistel, Henrik Bregnhøj, Colin A. Stedmon, Ursula S. McKnight
更新时间: 2018-11-01
摘要: Dissolved organic matter (DOM) is linked to the heterogeneous distribution of elevated arsenic (As) in groundwater used for drinking and irrigation purposes, but the relationship between DOM characteristics and arsenic mobility has yet to be fully understood. Here, DOM from groundwater sampled in the Bengal Basin region was characterized using both conventional bulk emission–excitation (EEM) spectroscopy and high-performance size-exclusion chromatography coupled to spectroscopy (HPSEC–EEM). Notably, application of the novel HPSEC–EEM approach permitted the total fluorescence of individual samples to be independently resolved into its underlying components. This allowed the external validation of the bulk-sample fluorescence decomposition and offered insight into the molecular size distribution of fluorescent DOM. Molecular size distributions were similar for the UVA fluorescent (C310 and C340) as well as the three visible fluorescent (C390, C440, and C500) components. There was a greater visible fluorescence in shallow aquifer samples (10–33 m) with high As (SH, up to 418 μg/L) than in samples from the same depth with lower As (up to 40 μg/L). This indicated a link between DOM quality and As mobility within the shallow aquifer. The deep aquifer samples (170–200 m) revealed DOM characteristics similar to SH samples but had low As concentrations (<4 μg/L), signifying that the deep aquifer is potentially vulnerable to As contamination. These findings pave the way for a more comprehensive assessment of the susceptibility of drinking water aquifers, thereby supporting the management of groundwater resources.
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14185. 题目: Enhanced Removal of Chlorophene and 17ß-estradiol by Mn(III) in a Mixture Solution with Humic Acid: Investigation of Reaction Kinetics and Formation of Co-oligomerization Products
文章编号: N18110118
期刊: Environmental Science & Technology
作者: Xinghao Wang, Siyuan Wang, Ruijuan Qu, Jiali Ge, Zunyao Wang, Cheng Gu
更新时间: 2018-11-01
摘要: Reaction with soluble Mn(II) has been considered as a main decay pathway for superoxide in natural waters, accompanied by an important Mn redox cycling. In this study, the interaction of Mn(II) and humic acid (HA) was investigated in visible light irradiated water. Our results indicate that HA may play a dual role to act as a photosensitizer to produce superoxide anions (O2) and as a strong ligand to stabilize the Mn(III), forming soluble Mn(III)L species for substrate transformation. Furthermore, the reaction kinetics, products, and mechanisms of chlorophene (CP) and estradiol (E2) mixture in the Mn(II)/HA/visible light reaction systems were assessed. The removal of CP and E2 was enhanced by 24.3% and 13.2%, respectively, in mixture solution at initial concentration of 1.0 μM for each target contaminant, as compared to the case of single-compound degradation. Product identification and density functional theory calculations indicated that cross-coupling reaction of CP and E2 radicals was more likely to occur than the self-coupling reaction in mixture solution. In addition, estrogenic activities of initial reaction solution were also effectively decreased during the transformation process. These findings provide new insights into Mn(III)-mediated reactions to better understand the environmental fate of organic contaminant mixture in waters.
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14186. 题目: Lignin and holocellulose from coir pith involved in trimethylamine (fishy odor) adsorption
文章编号: N18110117
期刊: Journal of Environmental Sciences
作者: Nuttapong Santawee, Chairat Treesubsuntorn, Paitip Thiravetyan
更新时间: 2018-11-01
摘要: Coir pith is a highly potential adsorbent for adsorbing trimethylamine (TMA). It harbors a higher adsorption capacity for TMA compared to commercial activated carbon (CAC). It was found that lignin and holocellulose extracted from coir pith played an important role in TMA adsorption. Lignin itself had the highest TMA adsorption capacity (269.01 mg/g) followed by holocellulose (75.43 mg/g), coir pith (14.3 mg/g) and CAC (10.26 mg/g), respectively. The pseudo-first- and second orders were applied to the kinetic data. For the adsorption of TMA by coir pith, the best fit was achieved by the pseudo-second order. Thermodynamic studies showed an endothermic and physico-chemical adsorption process between TMA and the coir pith. TMA desorption study suggested that only 14%–47% of TMA was desorbed with distilled water. In addition, Fourier transform-infrared (FT-IR) spectra showed that C–H bond (methyl group), C–O bond from phenolic alcohol and C–O bond from tertiary alcohol in lignin and holocellulose were involved in TMA adsorption. Coir pith-based filter showed high TMA adsorption efficiency (98%) and kept constant for more than 48 days in a continuous system. Pilot scale experiment, coir pith beads filter could be succesfully applied as a packing material for TMA removal. Therefore, coir pith can be used as a promising packing material for TMA treatment at contaminated site.
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14187. 题目: N-doped hierarchically porous carbon for highly efficient metal-free catalytic activation of peroxymonosulfate in water: A non-radical mechanism
文章编号: N18110116
期刊: Chemosphere
作者: Yangke Long, Sifan Bu, Yixuan Huang, Yueqi Shao, Ling Xiao, Xiaowen Shi
更新时间: 2018-11-01
摘要: Metal-free carbo-catalyst has recently emerged as a promising candidate as a substituent for tradition-metal based heterogeneous catalyst for catalytic activation of peroxymonosulfate (PMS). However, most reported carbo-catalysts suffer from low catalytic efficiency and poor stability, thus a high-performance catalyst is urgently desired. In this study, a novel carbo-catalyst (NHPC-800), prepared by using tannic acid and dicyandiamide as renewable carbon/nitrogen feedstocks via a simple pyrolysis route, is reported as an activator of PMS with highly efficient catalytic ability and stability. The as-prepared NHPC-800 possesses as high as 22.4 atom% of nitrogen dopants and a hierarchically porous structure with abundant meso/macropores, accompanied by the abundant edges and wrinkles, which supply sufficient exposed catalytically active centers and fast electrons/mass transportations. Using rhodamine B as a model pollutant, the NHPC-800 shows a highly efficient catalytic ability which is superior to most reported carbo-catalysts and even some state-of-the-art metal catalysts. Based on competitive quenching experiments and electron paramagnetic resonance (EPR) results, a non-radical pathway involving the generation of 1O2 is responsible for the degradation of pollutants. Given that the NHPC-800 shows good recycling performance and strong resistance to adventitious interference such as anions and natural organic matters, we believe NHPC-800 can be a promising candidate for practical applications, and this study can provide inspirations for the further development of highly efficient carbo-catalysts.
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14188. 题目: Groundwater flooding: Ecosystem structure following an extreme recharge event
文章编号: N18110115
期刊: Science of The Total Environment
作者: Julia Reiss, Daniel M. Perkins, Katarina E. Fussmann, Stefan Krause, Cristina Canhoto, Paul Romeijn, Anne L. Robertson
更新时间: 2018-11-01
摘要: 1)Aquifers are recharged by surface water percolating through soil and rock and by connections with surface streams and rivers. Extreme rainfall can cause extensive flooding of surface waters and, eventually, of groundwaters. However, how the resultant changes in nutrients impact groundwater organisms and the structure of groundwater food webs is largely unknown.2)We monitored abiotic (nutrients, temperature and more) and biotic (all organismal groups except viruses) conditions in eight groundwater boreholes in two locations in a chalk aquifer over the course of 25 weeks (ten sampling occasions), following an extreme rainfall- and groundwater-flooding event in the UK.3)We show that groundwater flooding can cause substantial nutrient fertilisation of aquifers – nutrient concentrations (especially dissolved organic carbon) in the groundwater were highest when we started the sampling campaign, directly following the flood event, and then decreased over time while groundwater levels also declined back to their baseline.4)Bacteria in the open water (i.e. bacteria not associated with sediment) became more abundant as the water table and DOC concentrations decreased. Importantly their functional richness tracked the DOC patterns, illustrating that bacteria were responsible for respiring DOC. Microbial metabolic activity and bacterial respiration, measured using smart tracers, supported this finding; DOC and microbial respiration showed a positive correlation.5)The other biota (protists, micro- and macro-metazoans) showed different abundance patterns over time, but importantly, the entire sediment community, ranging from bacteria to macrofaunal species, showed a strong community size structure (mean size spectra slope: −1.12). Size spectra changed gradually through time towards steeper slopes, except in the very deep aquifer.6)Our approach allowed us to demonstrate that groundwater communities track extreme changes in their usually stable environment, highlighting that they potentially buffer environmental change, although we still do not know what the limits of this ‘service’ might be.
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14189. 题目: Intensification of light green SF yellowish (LGSFY) photodegradion in water by iodate ions: Iodine radicals implication in the degradation process and impacts of water matrix components
文章编号: N18110114
期刊: Science of The Total Environment
作者: Amal Haddad, Slimane Merouani, Chiraz Hannachi, Oualid Hamdaoui, Béchir Hamrouni
更新时间: 2018-11-01
摘要: The results of this work showed that UV/IO3 oxidation process supplies good performance in the degradation of light green SF yellowish (LGSFY) dye in deionized water. This process generated reactive iodine radicals that make the degradation much faster than the sole UV irradiation. The assistance of UV-irradiation by 10 mM of iodate increased the LGSFY removal after 10 min from 36% to 90% for C0 = 10 mg/L and from 18% to 85% for C0 = 20 mg/L. In parallel, a 2.5 and 4.72-fold increase in the LGSFY initial degradation rate, as compared with UV alone, were recorded for, respectively, 10 and 20 mg/L of LGSFY. IO2 and IO played the most important role in the degradation of LGSFY by the UV/IO3 process. The degradation was not affected by the presence of chloride and nitrate ions even at high dosage levels (up to 0.1 M), whereas sulfate ions reduced the valuable effect of iodate to the half when they are present at 0.1 M. Correspondingly, humic acids, at usual concentrations as those measured in natural waters, did not affect significantly the LGSFY degradation upon photoactivated iodate process. These results revealed, in one part, that iodine radicals are selective oxidants and, in another part, that the process is likely to remove organic dyes from natural water which often contains mineral constitutes and humic substances.
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14190. 题目: Flow conditions influence diuron toxicokinetics and toxicodynamics in freshwater biofilms
文章编号: N18110113
期刊: Science of The Total Environment
作者: Betty Chaumet, Soizic Morin, Océane Hourtané, Joan Artigas, Brigitte Delest, Mélissa Eon, Nicolas Mazzella
更新时间: 2018-11-01
摘要: Biofilms are considered as good bioindicators of contamination by means of their capacity to react quickly to xenobiotics exposure, and their pivotal role in sustaining the aquatic trophic web. The exchanges of dissolved substances between water column and biofilm can be modulated by flow velocity. This study deals with toxicokinetic (transfer mechanisms) and toxicodynamic (effects) modelling of pesticides under two contrasted flow conditions.Diuron was used to run a 2-h kinetic study on mature biofilms in river channels. Two flow conditions were considered (⋘1 cm·s−1: lentic environments such as ponds, 2 cm·s−1: lotic environments such as watercourses). Three concentrations were tested in order to estimate contamination levels in biofilms: 0, 5 (environmentally relevant concentration) and 50 (to determine the concentration effect) μg·L−1. The effect of the above-mentioned factors was also assessed on biofilms photosynthesis inhibition. For successive sampling times between 0 and 2 h, the raw biofilms and EPS tightly bound to cells plus microorganisms (T-EPS-M), were physically separated and analysed for diuron accumulation and structural and functional microbial descriptors.Diuron amounts accumulated in biofilm increased with increasing diuron exposure. Biofilms accumulated higher amounts of diuron at the lower flow velocity compared to high flow for raw biofilms, while accumulation in the T-EPS-M fraction was similar between flow conditions. Consequently, both flow velocity and diuron exposure had an influence on diuron bioaccumulation and distribution. Photosynthesis inhibition over time was directly linked to the exposure concentration of diuron recorded in the T-EPS-M fraction.These results suggest that flow causes a loss of organic matter in biofilms, decreasing the total accumulation of diuron, especially within diffusible EPS. As pesticide distribution in biofilm is a major factor in the onset of toxicity, the novel fractioning method presented here will improve further toxicokinetic and toxicodynamic studies dealing with biofilms exposed to organic toxicants.
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14191. 题目: Reactivation and pilot-scale application of long-term storage denitrification biofilm based on flow cytometry
文章编号: N18110112
期刊: Water Research
作者: Shuo Wang, Kai Qian, Yin Zhu, Xuesong Yi, Guangsheng Zhang, Guocheng Du, Joo-Hwa Tay, Ji Li
更新时间: 2018-11-01
摘要: The work provides a method on the basis of flow cytometry to evaluate the performance of denitrification biofilm during the preservation, reactivation and pilot-scale operation process. The viable cell ratio of denitrification biofilm significantly reduced and further led to the decrease of denitrification capacity after long-term preservation for 5 months. Protein component in tightly bound extracellular polymeric substances (TB-EPS) could serve to enhance microbial adhesion and promote denitrification biofilm formation. With the significant correlation of viable cell ratio and microbial characteristics, 4°C was more appropriate for preserving denitrification biofilm and conducive to maintain the relatively high denitrification capacity. A maximum denitrification rate of 5.80 gNO3--N/m2·d was obtained in pilot-scale anoxic-oxic (AO) process and Dechloromonas became greater prevalence in denitrification suspended carriers. Furthermore, the enrichment of Pseudomonas, Parcubacteria, Acidovorax, Aquabacterium and Unclassified_Flavobacteriaceae enhanced biofilm formation and nutrient conservation. The significantly positive correlation between viable cell ratio and the ratio of nitrate reduction to COD consumption was discovered, and the indices of Chao, ACE, Shannon and Simpson of denitrification biofilm were positively correlated with viable cell ratio, meaning that flow cytometry analysis was reasonable and suitable to evaluate the performances of denitrification biofilm.
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14192. 题目: Using upstream oxidants to minimize surface biofouling and improve hydraulic performance in GAC biofilters
文章编号: N18110111
期刊: Water Research
作者: Glen Andrew de Vera, Chance Lauderdale, Christina Alito, Jennifer Hooper, Eric C. Wert
更新时间: 2018-11-01
摘要: The combination of biological growth and particle loading can adversely affect hydraulic performance in drinking water biofilters. In this study, upstream oxidant addition was used to distribute biologically-derived filter clogging in granular activated carbon (GAC) biofilters. Oxidant penetration was assessed during pilot-scale operation and backwashing of dual media (GAC/sand) and multimedia (GAC/anthracite/sand) biofilters. Influent chlorine (HOCl), monochloramine (NH2Cl), and hydrogen peroxide (H2O2) residuals were optimized to react with the GAC surface in the upper portion of the filter media bed (depth < 0.5 m) to attenuate biomass development. As the oxidant residual was quenched by surface-mediated reaction with the filter media, biomass growth was promoted deeper in the filter bed (depth > 0.5 m). The oxidant-induced effects on biomass and hydraulic performance were monitored through measurements of adenosine triphosphate (ATP) and head loss accumulation at different media depths. Addition of oxidants (e.g., 0.6 mg Cl2/L HOCl) could decrease terminal head loss by 20% in dual media filters and 40% in multimedia filters. These hydraulic benefits were achieved without significantly affecting removal of assimilable organic carbon (AOC), total organic carbon (TOC), turbidity, and particle counts. Oxidant type, residual concentration, media type, media age, and media depth influenced the passage of oxidant residuals and distribution of filter biomass. When oxidants were added during backwashing, oxidant residual was quenched through the bed depth from a combination of reactions with GAC media and biofilm degradation. This attenuation of residual oxidant may prevent the oxidant residual from penetrating the entire bed depth, potentially compromising backwashing objectives.
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14193. 题目: Overlapping Anthropogenic Effects on Hydrologic and Seasonal Trends in DOC in a Surface Water Dependent Water Utility
文章编号: N18110110
期刊: Water Research
作者: Thomas B. Parr, Shreeram P. Inamdar, Matthew J. Miller
更新时间: 2018-11-01
摘要: Drinking water supplies are increasingly affected by overlapping anthropogenic global change processes. As a key currency of ecosystem function in aquatic ecosystems, dissolved organic carbon (DOC) concentration and composition is sensitive to many global change processes. However, DOC must also be removed to avoid the production of harmful disinfection byproducts as water is processed. Thus, understanding the effects of global change processes on the seasonal and long-term dynamics of DOC composition and concentration is critical for ensuring the sustainability of drinking water supplies. To understand these dynamics, we analyzed a novel 11-year time series of stream water DOC concentration and composition using Weighted Regressions on Time Discharge and Season (WRTDS) to understand the influences of co-occurring changes in climate and atmospheric deposition. We also discuss the implications for water supply provision and management. We found that, during our study period, overlapping global change processes in the watershed had the net effect of increasing the DOC aromaticity, as measured by SUVA254, at moderate to high discharge levels during the late spring and early summer and the autumn and early winter. However, changes in DOC concentration were more dynamic and we observed both increasing and decreasing trends depending on season and hydrologic state. During summer, at low to moderate flow levels we observed a significant (p<0.05) increase in DOC concentration. During autumn, at moderate to high flow levels we observed a significant (p<0.05) decrease in DOC concentration and an increase in SUVA254. For drinking water providers, our results suggest that close monitoring of source waters must be coupled with the development of plans accounting for season- and hydrology-specific long-term changes.
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14194. 题目: Evaluating membrane fouling potentials of dissolved organic matter in brackish water
文章编号: N18110109
期刊: Water Research
作者: Sanghun Park, Taewoo Nam, Jeongyeop You, Eun-Sik Kim, Ilhwan Choi, Jongkwan Park, Kyung Hwa Cho
更新时间: 2018-11-01
摘要: Isolating dissolved organic matter (DOM) is a preliminary step that improves the accuracy of its characterization. In this study, DOM in brackish water was clearly separated and evaluated by multiple characterization analyses. The sample was divided into three fractions by preparative high-performance liquid chromatography (preparative HPLC) according to molecular size. The homogeneity of each fraction was estimated by analytical size exclusion chromatography (SEC) and fluorescence excitation-emission matrix (FEEM). Pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) and liquid chromatography-organic carbon detection (LC-OCD) were used to characterize the physicochemical properties of each fraction. Py-GC/MS revealed that Fraction 1 consisted of evenly distributed organic matter in order polysaccharides, proteins, polyhydroxy aromatics, lignins, and lipids. However, Fraction 2 was primarily composed of dominant lipids and low portion of proteins, and Fraction 3 was composed predominantly of lignins and lipids. The LC-OCD results showed that Fractions 1 and 2 had similar organic carbon (OC) compositions: a humic substance (ca. 37%), building blocks (ca. 10%), and neutrals (ca. 37%), whereas Fraction 3 contained a high proportion of neutrals (62%). In the fouling experiments, the distinct DOM characteristics in each fraction resulted in different declining flux behaviors, ranked as: Fraction 2 > Fraction 1 > Fraction 3.
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14195. 题目: Enhanced degradation of organic contaminants by zero-valent iron/sulfite process under simulated sunlight irradiation
文章编号: N18110108
期刊: Water Research
作者: Pengchao Xie, Li Zhang, Jinhui Chen, Jiaqi Ding, Ying Wan, Songlin Wang, Zongping Wang, Aijiao Zhou, Jun Ma
更新时间: 2018-11-01
摘要: Degradation of propranolol (PrP) by a combined zero-valent iron and sulfite system under simulated sunlight irradiation (ZVI/sulfite/photo) was investigated. Simulated sunlight irradiation enhanced the degradation of PrP by accelerating the decomposition of ferric sulfite complex as a result to producing sulfite radical (SO3•−). As bubbles would block the transport of photons in the reaction solution, mechanical aeration rather than purging air was suggested to sustain the essential dissolved oxygen. The degradation of PrP increased with the elevation of initial ZVI concentration from 0.05 to 0.5 mM, but decreased a little with further increasing ZVI concentration to 1.0 mM. The degradation of PrP raised from 68.5% to 98.7% while sulfite dose increased from 0.1 to 2.0 mM. High removal efficiencies were always achieved when the initial PrP concentration ranged from 10 to 50 μM. As HSO3 which can efficiently complex Fe(II) and transfer Fe(III) to Fe(II) is the dominant species of sulfite at pH 4.0–6.0, the highest removal of PrP was achieved at pH 4.0–6.0. The presence of bicarbonate and humic acid significantly retarded the removal of PrP, while chloride ions could promote the removal of PrP to some extent. SO4•−, HO and SO5•− were suggested to account for PrP removal, while SO4•− was evidenced to be the dominant radicals. Good reuse of ZVI in the system was also achieved as the removal of PrP kept higher than 80% after repeatedly used for 5 times. Possible degradation pathways of PrP in the ZVI/sulfite/photo system were accordingly proposed based on LC-MS and density functional theory calculation. The removal of amitriptyline, nitrobenzene, imipramine and methylparaben in the ZVI/sulfite/photo system was also evaluated. As a reducing agent, sulfite is expected to consume the possible formed bromine-containing intermediates as a result to inhibiting the formation of bromate, which is better than the activated persulfate system.
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14196. 题目: Capping with activated carbon reduces nutrient fluxes, denitrification and meiofauna in contaminated sediments
文章编号: N18110107
期刊: Water Research
作者: Stefano Bonaglia, Robert Rämö, Ugo Marzocchi, Léonie Le Bouille, Martine Leermakers, Francisco J.A. Nascimento, Jonas S. Gunnarsson
更新时间: 2018-11-01
摘要: Sediment capping with activated carbon (AC) is an effective technique used in remediation of contaminated sediments, but the ecological effects on benthic microbial activity and meiofauna communities have been largely neglected. This study presents results from a 4-week experiment investigating the influence of two powdered AC materials (bituminous coal-based and coconut shell-derived) and one control material (clay) on biogeochemical processes and meiofauna in contaminated sediments. Capping with AC induced a 62‒63% decrease in denitrification and a 66‒87 % decrease in dissimilatory nitrate reduction to ammonium (DNRA). Sediment porewater pH increased from 7.1 to 9.0 and 9.7 after addition of bituminous AC and biomass-derived AC, respectively. High pH (>8) persisted for at least two weeks in the bituminous AC and for at least 24 days in the coconut based AC, while capping with clay had no effect on pH. We observed a strong impact (nitrate fluxes being halved in presence of AC) on nitrification activity as nitrifiers are sensitive to high pH. This partly explains the significant decrease in nitrate reduction rates since denitrification was almost entirely coupled to nitrification. Total benthic metabolism estimated by sediment oxygen uptake was reduced by 30 and 43 % in presence of bituminous coal-based AC and coconut shell-derived AC, respectively. Meiofauna abundances decreased by 60‒62 % in the AC treatments. Taken together, these observations suggest that AC amendments deplete natural organic carbon, intended as food, to heterotrophic benthic communities. Phosphate efflux was 91 % lower in presence of bituminous AC compared to untreated sediment probably due to its content of aluminum (Al) oxides, which have high affinity for phosphate. This study demonstrates that capping with powdered AC produces significant effects on benthic biogeochemical fluxes, microbial processes and meiofauna abundances, which are likely due to an increase in porewater pH and to the sequestration of natural, sedimentary organic matter by AC particles.
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14197. 题目: Long-term residue and water management practice effects on particulate organic matter in a loessial soil in eastern Arkansas, USA
文章编号: N18110106
期刊: Geoderma
作者: Johan Desrochers, Kristofor R. Brye, Edward Gbur, Erik D. Pollock, Mary C. Savin
更新时间: 2018-11-01
摘要: Long-term sustainability of soils with a prolonged history of crop production can be better understood by characterizing soil aggregation, particularly the distribution of carbon (C) and nitrogen (N) among particulate organic matter (POM) fractions within various soil aggregate-size fractions. The objective of this field study was to evaluate the effects of residue level, residue burning, tillage, and irrigation on macro-aggregate (>250 μm), micro-aggregate (53–250 μm), coarse (>250 μm) and fine POM (53–250 μm), and silt-clay fractions and their associated C and N in the top 10 cm of a highly erodible loessial soil (Glossaquic Fraglossudalf) after 13 years of consistent management in a wheat-soybean, double-crop (WSDC) system in the Lower Mississippi River Delta region of eastern Arkansas. The total aggregated soil fraction was 11.2% greater (P = 0.02) in the no-tillage (NT)-irrigated compared to the average of the other three tillage-irrigation combinations, which did not differ. Averaged over irrigation, burn, and residue-level treatments, the C concentration in the sand-free macro-aggregate fraction was 8.8% less (P < 0.05) under conventional tillage (15.6 g kg−1) than under NT (17.1 g kg−1). Fine POM C and N concentrations within sand-free-adjusted aggregates were 1.9 times greater (P ≤ 0.04) in the burn-low (2.59 and 0.21 g kg−1, respectively) compared to the burn-high treatment (1.35 and 0.11 g kg−1, respectively), while that in the no-burn under either residue level, which did not differ, were intermediate (2.43 and 0.23 g kg−1, respectively). Results showed that alternative management practices, such as NT and non-burning, can contribute to improved soil health and long-term sustainability and the mitigation of climate-change-related greenhouse gas concentrations in the atmosphere by reducing SOM oxidation, microbial respiration, and carbon dioxide emissions.

14198. 题目: Assessing the pore structure and surface area of allophane-rich and non-allophanic topsoils by supercritical drying and chemical treatment
文章编号: N18110105
期刊: Geoderma
作者: R. Calvelo Pereira, M. Camps Arbestain, F.M. Kelliher, B.K.G. Theng, S.R. McNally, F. Macías, F. Guitián
更新时间: 2018-11-01
摘要: We have investigated the effect of supercritical drying (SD) on the porosity and the BET-N2 specific surface area (SSA) of five allophane-rich and three non-allophanic topsoils. The contribution of organic matter (OM) and short-range ordered (SRO) constituents to the nanoscale porosity (<100 nm size) and SSA was also evaluated following chemical treatments to oxidise OM and then remove the SRO phase. The average pore volume and SSA of the soils, measured after SD, are greater than the values obtained after air drying. For soils that are rich in SRO constituents, oxidation of OM leads to an increase in SSA. This observation is attributed to the unblocking of pore necks previously covered by OM, while the subsequent removal of SRO constituents causes a sharp decrease in SSA. The SRO constituents containing oxalate-extractable Al, are the major contributors to the SSA of the inorganic fraction. Besides confirming that SD can help preserve the nanoscale porosity of allophane-rich soils, the results highlight the contribution of SRO constituents to the SSA of soils and their ability to accumulate OM.

14199. 题目: Growth of Rhodes grass and leaching of ions from seawater neutralized bauxite residues after amendment with gypsum and organic wastes
文章编号: N18110104
期刊: Journal of Environmental Management
作者: Yaying Li, Richard J. Haynes, Irena Chandrawana, Ya-Feng Zhou
更新时间: 2018-11-01
摘要: A 32-week leaching column study was carried out in the greenhouse to investigate the effects of incorporation of gypsum, cattle manure, biosolids, gypsum plus cattle manure and gypsum plus biosolids into the topsoil layer (0–10 cm) on growth of Rhodes grass, and on root distribution and chemical and microbial properties in the topsoil and subsoil (10–30 cm) layers of seawater neutralized bauxite residues. The columns were leached for a period of 8 weeks prior to sowing Rhodes grass and during that time the bulk of the salts accumulated during seawater neutralization were leached out. The main cation leached was Na+ and the main balancing anions were Cl and SO42−. During this period the pH of leachates rose from 7 to 8 up to 9–10. At the end of the study, exchangeable Na and pH were lowered in the surface horizon by all treatments with a combination of gypsum plus organic amendments having the greatest effect. The latter treatments also caused a significant decrease in pH, extractable Al and exchangeable Na in the subsoil. Rhodes grass dry matter production followed the order Control < gypsum < cattle manure = gypsum plus cattle manure < biosolids = gypsum plus biosolids. Growth of roots into the subsoil layer was inhibited in the Control and gypsum treatments but when organic amendments were applied, 50% or more of root dry matter was recovered in the subsoil layer. It was concluded that incorporating a combination of gypsum and organic matter into the surface soil is an effective strategy for revegetation of bauxite residue.

14200. 题目: Kinetics studies and mechanistic considerations on the reactions of superoxide radical ions with dissolved organic matter
文章编号: N18110103
期刊: Water Research
作者: Jianzhong Ma, Huaxi Zhou, Shuwen Yan, Weihua Song
更新时间: 2018-11-01
摘要: Superoxide ion (O2•−) is one of the short lived reactive oxygen species (ROS) formed in aquatic environments. The reactions of O2•− with the model dissolved organic matter (DOM) were studied using a chemiluminescent analysis method under relevant environmental conditions. The reaction of O2•− with DOM produced reduced DOM (DOM•−) by fast one-electron-transfer in the initial stage. This process resulted an initial “loss” in the O2•− decay kinetics. DOM•− is unstable which will continue react with O2•− generating H2O2 to complete a catalytic dismutation cycle. Based on analyzing the observed pseudo-first order O2•− decay rates (kpseudo), the quasi-steady-state concentration of DOM•− is found to be equal to the initial loss of O2•−. Thus, the rate constant for DOM•− with HO2/O2•− is derived to be (1.1−1.9) × 106 M-1 s-1 in the temperature range of 7.8 to 41.4 °C. Meanwhile, the apparent rate constant for DOM with O2•− in a flow cell during a short time (2.25 s) is measured as (1.5−3.3) × 103 MC-1 s-1 in the temperature range of 8.2 to 38.6 °C. These temperature dependent O2•− reaction rate constants present an apparent activation energy of (19.6 ± 2.9) kJ molC-1 for DOM, while that of DOM•− (12.5 ± 3.5 kJ mol-1) is lower. For the pseudo-first order decay rate of O2•−, the catalyzed-dismutation by metal components ranges from 13-23%; the contribution by aromatic ketones of DOM is estimated to be 10-13% by using NaBH4 reduction method. The residual contribution might mainly occur at the quinone-like groups, which contributed 64% to 77% to the total dismutation. The pH effects on the apparent catalytic rate constants dominate the reaction of O2•− with DOM. The present work suggests that DOM is an important sink for O2•− in aquatic environments. Furthermore, we proposed that the reaction of O2•− with DOM could be a potential source of DOM•− in natural water.
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