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25161. 题目: The concentration of dissolved organic matter impacts the metabolic response in Daphnia magna exposed to 17α-ethynylestradiol and perfluorooctane sulfonate
文章编号: N18121404
期刊: Ecotoxicology and Environmental Safety
作者: Vera Kovacevic, André J. Simpson, Myrna J. Simpson
更新时间: 2018-12-14
摘要: The pharmaceutical 17α-ethynylestradiol (EE2) and the industrial chemical perfluorooctane sulfonate (PFOS) are organic contaminants frequently detected in freshwater environments. It is hypothesized that hydrophobic organic contaminants can sorb to dissolved organic matter (DOM) and this may reduce the toxicity of these contaminants by reducing the contaminants’ bioavailability. To investigate this hypothesis, ¹H nuclear magnetic resonance (NMR)-based metabolomics was used to determine how the metabolome of Daphnia magna changes when a range of DOM concentrations are added during EE2 and PFOS exposure experiments. D. magna were exposed for 48 h to sub-lethal concentrations of 1 mg/L EE2 or 30 mg/L PFOS in the presence of 0, 1, 2, 3 and 4 mg dissolved organic carbon (DOC)/L. EE2 exposure resulted in increased amino acids and decreased glucose in D. magna. All DOM concentrations were able to lessen these metabolite disturbances from EE2 exposure, likely due to reductions in the bioavailability of EE2 through interactions with DOM. Exposure to PFOS resulted in decreased amino acids, and the presence of 1 mg DOC/L did not alter this metabolic response. However, PFOS exposure with the higher DOM concentrations resulted in a different pattern of metabolite changes which may be due to combined impacts of PFOS and DOM on the metabolome or due to an increase in PFOS bioavailability and uptake in D. magna. These results suggest that the concentration of DOM influences the sensitive biochemical changes in organisms that occur during acute sub-lethal exposure to organic contaminants.
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25162. 题目: Improving agricultural water use efficiency with biochar – A synthesis of biochar effects on water storage and fluxes across scales
文章编号: N18121403
期刊: Science of The Total Environment
作者: Benjamin M.C. Fischer, Stefano Manzoni, Laura Morillas, Monica Garcia, Mark S. Johnson, Steve W. Lyon
更新时间: 2018-12-14
摘要: There is an urgent need to develop agricultural methods that balance water supply and demand while at the same time improve resilience to climate variability. A promising instrument to address this need is biochar – a charcoal made from pyrolyzed organic material. However, it is often unclear how, if at all, biochar improves soil water availability, plant water consumption rates and crop yields. To address this question, we synthesized literature-derived observational data and evaluated the effects of biochar on evapotranspiration using a minimal soil water balance model. Results from the model were interpreted in the Budyko framework to assess how climatic conditions mediate the impacts of biochar on water fluxes. Our analysis of literature-derived observational data showed that while biochar addition generally increases the soil water holding capacity, it can have variable impacts on soil water retention relative to control conditions. Our modelling demonstrated that biochar increases long-term evapotranspiration rates, and therefore plant water availability, by increasing soil water retention capacity – especially in water-limited regions. Biochar amendments generally increased crop yields (75% of the compiled studies) and, in several cases (35% of the compiled studies), biochar amendments simultaneously increased crop yield and water use efficiencies. Hence, while biochar amendments are promising, the potential for variable impact highlights the need for targeted research on how biochar affects the soil-plant-water cycle.
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25163. 题目: Characteristics and mechanisms of chlorpyrifos and chlorpyrifos-methyl adsorption onto biochars: Influence of deashing and low molecular weight organic acid (LMWOA) aging and co-existence
文章编号: N18121402
期刊: Science of The Total Environment
作者: Hao Zheng, Qian Zhang, Guocheng Liu, Xianxiang Luo, Fengmin Li, Yipeng Zhang, Zhenyu Wang
更新时间: 2018-12-14
摘要: The effects of inherent minerals in biochars and low molecular weight organic acids (LMWOAs) on chlorpyrifos and chlorpyrifos-methyl adsorption by biochars are unclear. We examined the sorption of chlorpyrifos and chlorpyrifos-methyl onto giant reed-derived biochars before and after deashing or LMWOA aging. The effect of citric acid (CA) as a co-solute on the sorption of chlorpyrifos and chlorpyrifos-methyl was also investigated. With increasing temperature (300–600 °C), the adsorption capacity of biochars increased from 4.32 to 14.8 mg/g for chlorpyrifos and from 15.0 to 50.5 mg/g for chlorpyrifos-methyl. This can be explained by the fact that higher temperature biochar had more aromatic units and pores for capturing more sorbates. The deashing and LMWOA aging treatments exposed more carbon surfaces and improved the porosity of biochar, thus favoring sorption. Further, the deashing treatment resulted in greater sorption enhancement, when compared with the LMWOA aging treatment. At pH 6.5, CA²⁻ and CA³⁻ chelated Ca²⁺ via bridging at CA concentration below 10 mmol/L, thus reducing the competition of Ca²⁺ for aromatic surfaces and COO⁻/OH groups. When the CA concentration was above 20 mmol/L, CA²⁻, CA³⁻, and [Ca(CA)₂]^x− inhibited the sorption of chlorpyrifos and chlorpyrifos-methyl by competing for carbon sites and pores of biochar. These findings will help guide the practical application of biochar in pesticide-contaminated water and soil, and to better understand the role of biochar in the transport, fate, and bioavailability of organophosphorus pesticides in the rhizosphere.
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25164. 题目: Effects of straw amendment on selenium aging in soils: Mechanism and influential factors
文章编号: N18121401
期刊: Science of The Total Environment
作者: Dan Wang, Ming-yue Xue, Ying-kun Wang, De-zhi Zhou, Li Tang, Sheng-yan Cao, Yu-hong Wei, Chen Yang, Dong-Li Liang
更新时间: 2018-12-14
摘要: Soil dissolved organic matter (DOM) alters heavy metal availability, but whether straw amendment can manipulate soil selenium (Se) speciation and availability through DOM mineralization remains unclear. In this study, allochthonous maize straw and selenate were incubated together in four different soils for 1 y. The transformation and availability of DOM associated Se (DOM-Se) was investigated during aging. Results indicated that soil solution and soil particle surfaces were dominated by hexavalent hydrophilic acid-bound Se (Hy-Se). The amount of fulvic acid bound Se in soil solution (SOL-FA-Se) was higher than humic acid bound Se in soil solution (SOL-HA-Se), except in krasnozems, and mainly existed as hexavalent Se (Se(VI)). Tetravalent Se (Se(IV)) was the main valence state of FA-Se adsorbed on soil particle surfaces (EX-FA-Se) after 5 w of aging. The proportion of soil-available Se (SOL + EX-Se) decreased with increasing straw rate. However, under an application rate of 7500 kg·hm⁻², soluble Se fraction (SOL-Se) reduction was minimal in acidic soils (18.7%–34.7%), and the organic bound Se fraction (OM-Se) was maximally promoted in alkaline soils (18.2%–39.1%). FA and HON could enhance the availability of Se in the soil solution and on particle surfaces of acidic soil with high organic matter content. While Se incorporation with HA could accelerate the fixation of Se into the solid phase of soil. Three mechanisms were involved in DOM-Se aging: (1) Reduction, ligand adsorption, and inner/outer-sphere complexation associated with the functional groups of straw-derived DOM, including hydroxyls, carboxyl, methyl, and aromatic phenolic compounds; (2) interconnection of EX-FA-Se between non-residual and residual Se pools; and (3) promotion by soil electrical conductivity (EC), clay, OM, and straw application. The dual effect of DOM on Se aging was highly reliant on the characteristics of the materials and soil properties. In conclusion, straw amendment could return selenium in soil and reduce soluble Se loss.
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25165. 题目: Microbial oxidation of nitrogen supplied as selected organic nitrogen compounds in the South Atlantic Bight
文章编号: N18121313
期刊: Limnology and Oceanography
作者: Julian Damashek, Bradley B. Tolar, Qian Liu, Aimee O. Okotie‐Oyekan, Natalie J. Wallsgrove, Brian N. Popp, James T. Hollibaugh
更新时间: 2018-12-13
摘要: Dissolved organic nitrogen (DON) can account for a large fraction of the dissolved nitrogen (N) pool in the ocean, but the cycling of marine DON is poorly understood. Recent discoveries that urea‐ and cyanate‐N can be oxidized by some strains of Thaumarchaeota suggest that these abundant microbes may be able to access and oxidize a fraction of the DON pool. However, measurements of the oxidation of N supplied as DON compounds are scarce. Here, we compare oxidation rates of N supplied as a variety of DON compounds in samples from Georgia coastal waters, where nitrifier communities are numerically dominated by Thaumarchaeota. Our data indicate that polyamine‐N is particularly amenable to oxidation compared to the other DON compounds tested. Oxidation of N supplied as putrescine (1,4‐diaminobutane) was generally higher than that of N supplied as glutamate, arginine, or urea, and was consistently 5–10% of the ammonia oxidation rate. Our data also suggest that the oxidation rate of polyamine‐N may increase as the length of the carbon skeleton increases. Oxidation of N supplied as putrescine, urea, and glutamate were all highest near the coast and lower further offshore, consistent with patterns of ammonia oxidation in these waters. Though it is unclear whether oxidation of polyamine‐N reflects direct oxidation by Thaumarchaeota or combines remineralization and subsequent ammonia oxidation, more rapid oxidation of N from putrescine compared to amino acids or urea suggests that polyamine‐N may contribute significantly to nitrification in the ocean.

25166. 题目: Spatial variation of earthworm communities and soil organic carbon in temperate agroforestry
文章编号: N18121312
期刊: Biology and Fertility of Soils
作者: Rémi Cardinael, Kevin Hoeffner, Claire Chenu, Tiphaine Chevallier, Camille Béral, Antoine Dewisme, Daniel Cluzeau
更新时间: 2018-12-13
摘要: The aim of this study was to assess how soil organic C (SOC) stocks and earthworm communities were modified in agroforestry systems compared to treeless control plots and within the agroforestry plots (tree rows vs alleys). We used a network of 13 silvoarable agroforestry sites in France along a north/south gradient. Total earthworm abundance and biomass were significantly higher in the tree rows than those in the control plots, but were not modified in the alleys compared to those in the control plots. Earthworm species richness, Shannon index, and species evenness were significantly higher in the tree rows than those in the alleys. Total abundance of epigeic, epi-anecic, strict anecic, and endogeic was higher in the tree rows. Surprisingly, earthworm individual weight was significantly lower in the tree rows than that in the alleys and in the control plots. SOC stocks were significantly higher in the tree rows compared to that in the control plots across all sites. Despite higher SOC stocks in the tree rows, the amount of available C per earthworm individual was lower compared to those in the control. The absence of disturbance (no tillage, no fertilizers, no pesticides) in the tree rows rather than increased SOC stocks therefore seems to be the main factor explaining the increased total abundance, biomass, and diversity of earthworms. The observed differences in earthworm communities between tree rows and alleys may lead to modified and spatially structured SOC dynamics within agroforestry plots.

25167. 题目: Liquid fertilizer production by ammonia recovery from treated ammonia-rich regenerated streams using liquid-liquid membrane contactors
文章编号: N18121311
期刊: Chemical Engineering Journal
作者: X. Vecino, M. Reig, B. Bhushan, O. Gibert, C. Valderrama, J.L. Cortina
更新时间: 2018-12-13
摘要: The nitrogen load on urban wastewater should be considered as a secondary resource for nitrogen-based fertilizers. From this point of view, ammonia-rich streams obtained from a regeneration step with zeolites using 70–80 g NaOH/L could contain up to 3.5–4.5 g NH₃/L as well as other ionic species (Na⁺, K⁺, Ca²⁺, Mg²⁺) and dissolved organic matter (DOM). Thus, they could be treated to obtain a valuable product composed by ammonia for fertilizing applications. A sorption pre-treatment process was carried out to remove the residual amount of DOM and to reduce membrane fouling before processing with hollow fibres liquid-liquid membrane contactors (HF-LLMC). Polypropylene HF-LLMC was used to selectively extract ammonia in single or two-step configurations using different acid stripping solutions (H₃PO₄, HNO₃ or a mixture of HNO₃/H₃PO₄). For ammonia recovery, the ammonia mass transfer coefficient (K_m(NH₃)) and water transport by HF-LLMC were determined. H₃PO₄ was found to be the best acid stripping solution by one-step HF-LLMC; the ammonia removal was 76% with a K_m(NH₃) of 8.8 × 10⁻⁷ m/s. Additionally, the ammonia was concentrated 26 times, and it was recovered as multi-nutrient liquid fertilizer (NP) composed of 7.8% N and 21.6% P₂O₅. Furthermore, ammonia recovery was increased, reaching values up to 94%, through two-step HF-LLMC, and again H₃PO₄ was used as stripping solution. Finally, water transport from the feed to the stripping phase was estimated to be 0.022 L/m²·h for one-step HF-LLMC with H₃PO₄. Finally, the use of UV–Vis and 2D-Fluorescence was shown to be a successful approach for monitoring pore wetting events.
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25168. 题目: Investigation on the control of phosphate leaching by sorption and colloidal transport: Column studies and multi-surface complexation modelling
文章编号: N18121310
期刊: Applied Geochemistry
作者: Ruben Warrinnier, Thomas Goossens, Fien Amery, Thijs Vanden Nest, Mieke Verbeeck, Erik Smolders
更新时间: 2018-12-13
摘要: Surface complexation modelling (SCM) is a powerful tool to estimate speciation and fate of solutes in soil, provided sufficient model validation. This study aims to describe phosphate (PO₄) leaching with SCM. The leachate phosphorus concentrations ([P]) of 120 unsaturated columns of contrasting agricultural soils were measured and modelled. Leachate [P] ranged 0.7–240 μM. Leachate [P] increased as the ratio of P to iron and aluminium (PAlFe) in acid oxalate soil extracts increased and as leachate Fe and Al concentrations ([Al + Fe]) increased. SCM was used to describe PO₄ sorption to ferrihydrite (CD-MUSIC model). This yielded adequate description of leachate [P] (RMSE_log10 = 0.39), but only when reactive PO₄ was described from isotopically exchangeable PO₄, when organic matter was included as the main competing adsorbate and when mobile colloidal ferrihydrite was included. The model reveals that colloidal PO₄ transport enhanced leachate PO₄ concentrations up to a factor 50 at small soil P content and small calcium (Ca²⁺) concentration in solution, as a large Ca²⁺ concentration enhances colloidal stability. This modelling approach explained that long-term application of organic fertilisers with higher Ca content reduced P leaching, likely due to the effect of Ca²⁺ on colloidal stability. A two-parameter empirical Langmuir model, based on soil Fe and Al oxyhydroxides, fitted data better than any SCM, suggesting that the empirical model might be advocated for application at large scale. This study revealed the power of SCM to better understand colloidal transport of P in soil.
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25169. 题目: The immediate effects of downslope cornstalk mulch (DCM) on sediment yield, runoff and runoff-associated dissolved carbon loss in a representative hillslope, Southwestern China
文章编号: N18121309
期刊: CATENA
作者: Tianyang Li, Siyue Li, Chuan Liang
更新时间: 2018-12-13
摘要: Dissolved carbon plays a pivotal role in carbon cycles and potentially affects ecological processes of water body. While stalk mulch can regulate soil and water losses, its effects on the export of dissolved carbon from soils are poorly understood. The main objective of this study was to determine the effects of rainfall intensity and downslope cornstalk mulch (the lengths of cornstalks along the slope, DCM) on runoff, sediment yield and dissolved carbon losses, including dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and dissolved total carbon (DTC). A series of field rainfall simulations were conducted on the steep fallow land (20 °) locating in a representative hillslope of southwestern China that experiences severe soil erosion, and data for runoff, sediment and dissolved carbon loss rates were obtained from triplet parallel plots (1.5 m long and 1 m wide for each one) using 60 min rainfall simulations at 30 and 90 mm h⁻¹ intensities on bare soils and 90 mm h⁻¹ intensity on soils with DCM (air-dried whole plants, 60% coverage and weight 1.65 kg), respectively. Rainfall intensity showed positive effects on runoff generation, sediment yield and loss rates of DIC, DOC and DTC. The plots with immediate DCM had no difference in runoff generation, but were 71.1% lower in sediment yield and 53.9% higher in DOC loss rate relative to the bare plots. The contribution of DIC to DTC increased from 35.9% to 59.6% with the increasing rainfall intensity. Cornstalk mulching appeared efficient in reducing sediment yield, but its adoption is likely to dramatically enhance DOC exports from soils with concerns for the quality of inland waters. Further research studies are required to discriminate between soil and cornstalk mulch contribution to DOC exports by overland flow.
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25170. 题目: Statistical analysis of lake sediment geochemical data for understanding surface geological factors and processes: An example from Amazonian upland lakes, Brazil
文章编号: N18121308
期刊: CATENA
作者: Prafulla Kumar Sahoo, José Tasso Felix Guimarães, Pedro Walfir Martins Souza-Filho, Mike A. Powell, Marcio Sousa da Silva, Aline Mamede Moraes, Ronnie Alves, Alessandro Sabá Leite, Wilson Nascimento Júnior, Tarcísio Magevski Rodrigues, Vladimir Eliodoro Costa, Roberto Dall'Agnol
更新时间: 2018-12-13
摘要: Statistical evaluation applied to geochemical data of upland lake sediments and their catchment basins rocks from Serra dos Carajás was used to identify geochemical signatures associated with underlying processes, sediment provenances, and source-sink relationship. The lakes are Violão, Amendoim and Três Irmãs - TI1, TI2 and TI3. A centred log-ratio transformation (clr) was used prior to multivariate analyses in order to eliminate closure issues in compositional data. Due to the similarity between δ¹⁵N values and organic sources (mainly from C3 plants), the three lakes were clustered together. Violão Lake receives largest organic contribution from autochthonous sources, such as siliceous sponge spicules and algae, except for it shallower portion (WNW extension), which is more similar to TI2, having low δ¹⁵N values that are similar to the isotopic signature of upland swamps. The upper continental crust (UCC) normalization pattern shows that sediments are mainly enriched in Fe, P and Se, which is closely related to the catchment lithology. The distribution of elements in TI2 is significantly different from the other lakes, because it is dominated by organic carbon, while the other lakes are a mix of detritus and organic carbon. Factor Analysis (FA) using clr-transformed data distinguishes several geochemical assemblages in the sediments, with the major detritic groups being similar to catchment basin laterites: the Ti-Zr-Hf-Nb-Y-HREEs group corresponds to resistant minerals which remained stable during lateritization; the LREEs group reflects mobilization and reprecipitation by REE bearing minerals; and the Al-V-Cr-Sc association reflects metavolcanic rock. The Fe-P-Mo-As-Zn cluster in the sediments is attributed to Fe-oxyhydroxide precipitation, while TOC-SO₃-Hg-Se group is controlled by organic matter. Principal Component Analysis (PCA) further indicates that detritic lake sediments are not directly derived from the parent rocks, but from weathered crusts, mainly ferruginous laterites and soils, which is consistent with their elements ratios.

25171. 题目: Lipid biomarker patterns reflect different formation environments of mussel- and tubeworm-dominated seep carbonates from the Gulf of Mexico (Atwater Valley and Green Canyon)
文章编号: N18121307
期刊: Chemical Geology
作者: Hongxiang Guan, Dong Feng, Daniel Birgel, Jörn Peckmann, Harry H. Roberts, Nengyou Wu, Duofu Chen
更新时间: 2018-12-13
摘要: Mussels and tubeworms thriving at many methane seeps typically live in symbiosis with chemosynthetic, chiefly methanotrophic or thiotrophic bacteria. It has been shown that the activities of chemosymbiotic animals can result in large differences in the sedimentary environments of their habitats. Here, we put forward the concept that such environmental variability can be archived in the lipid biomarker inventories of authigenic carbonates forming in different, locally confined environments at seeps, mussel beds and tubeworm bushes in this case. To test this hypothesis, lipid biomarker patterns of carbonates from mussel and tubeworm environments from two seep sites (Atwater Valley 340 and Green Canyon 852) of the Gulf of Mexico were analyzed. Previous work revealed stronger carbon isotope fractionation between the methane source and biomarkers of anaerobic methane oxidizing archaea-2 (ANME-2)/sulfate-reducing Desulfosarcina/Desulfococcus (DSS) consortia than for ANME-1/DSS consortia, both performing anaerobic oxidation of methane (AOM). Similar δ¹³C_methane values were found at the mussel and tubeworm sites from the same seeps and the local microbial consortia also appear to be largely similar based on the observed AOM biomarker inventories. Yet, a large average offset of 32‰ between the δ¹³C values of molecular fossils of sulfate-reducing bacteria (SRB) involved in AOM was observed, with lower values typifying tubeworm carbonates than mussel carbonates. This pattern is interpreted to reflect local effects on isotope fractionation caused by the chemosymbiotic metazoans at mussel- and tubeworm-dominated sites. At tubeworm-dominated sites, the excess sulfate produced by thiotrophic symbionts of tubeworms and pumped down into the sediment results in persistent production of AOM-derived bicarbonate and the enrichment of ¹²C in sub-surface sediments. Interestingly, tubeworm carbonates also contain high amounts of non-isoprenoidal dialkyl glycerol diethers (DAGEs) with extreme ¹³C depletions, representing compounds that derived from non-DSS cluster SRB. Most likely, ¹³C-depleted AOM-derived organic intermediates were used as carbon sources by the DAGE-producing non-DSS cluster SRB, possibly performing organoclastic sulfate reduction. Our study identifies significant variation in biomarker patterns between mussel and tubeworm carbonates at two seep sites in the Gulf of Mexico. Such variation allows to characterize different habitats at seeps, which are shaped by the interaction of chemosymbiotic seep metazoans and their symbionts with the local environment. Metazoan community composition apparently controls geobiological interaction in seep ecosystems to a large degree, which may allow tracing of the effects of chemosymbiosis into the rock record.

25172. 题目: Influence of COM-peptides/proteins on the properties of flocs formed at different shear rates
文章编号: N18121306
期刊: Journal of Environmental Sciences
作者: Monika Filipenska, Petra Vasatova, Lenka Pivokonska, Lenka Cermakova, Andrea Gonzalez-Torres, Rita K. Henderson, Jana Naceradska, Martin Pivokonsky
更新时间: 2018-12-13
摘要: Coagulation followed by floc separation is a key process for the removal of algal organic matter (AOM) in water treatment. Besides optimizing coagulation parameters, knowledge of the properties of AOM-flocs is essential to maximizing AOM removal. However, the impact of AOM on the floc properties remains unclear. This study investigated how peptides/proteins derived from the cellular organic matter (COM) of the cyanobacterium Microcystis aeruginosa influenced the size, structure, and shape of flocs formed at different shear rates (G). Flocs formed by kaolinite, COM-peptides/proteins and a mixture of the same were studied, and the effect of intermolecular interactions between floc components on floc properties was assessed. The coagulation experiments were performed in a Taylor–Couette reactor, with aluminum (Al) or ferric sulphate (Fe) utilized as coagulants. Image analysis was performed to gauge floc size and obtain data on fractal dimension. It was found that floc properties were affected by the presence of the COM-peptides/proteins and the coagulant used. COM-peptides/proteins increased floc size and porosity and widened floc size distributions. The Fe coagulant produced larger and less compact flocs than Al coagulant. Moreover, the decrease in floc size that occurred in parallel with increase in shear rate was not smooth in progress. A rapid change for the kaolinite-coagulant suspension and two rapid changes for the suspensions containing COM were observed. These were attributed to various intermolecular interactions between floc components participating in coagulation at different G. Based on the results obtained, shear rates suitable for efficient separation of flocs containing COM were suggested.
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25173. 题目: Release dynamics of As, Co, and Mo in a biochar treated soil under pre-definite redox conditions
文章编号: N18121305
期刊: Science of The Total Environment
作者: Ali El-Naggar, Sabry M. Shaheen, Zeng-Yei Hseu, Shan-Li Wang, Yong Sik Ok, Jörg Rinklebe
更新时间: 2018-12-13
摘要: This study assessed the impact of pre-definite redox potential (E_H) on the release dynamics and distribution of As, Co, and Mo between the dissolved and colloidal phases as well as their potential mobility and phytoavailability in the sediment phase of a mining soil treated with rice hull biochar (BC). The experiment was conducted from controlled moderately-reducing to oxidizing conditions using an automated biogeochemical microcosm system. Arsenic and Mo were more abundant in the dissolved phase due to their predominant in potential mobile fractions, while Co was more abundant in the colloidal phase due to its association with Fe-(hydr)oxides. Biochar increased the dissolved and colloidal concentrations of As, the dissolved concentration of Co, and the colloidal concentration of Mo under oxidizing condition. On the other hand, the application of BC decreased the dissolved concentration of Mo and the colloidal concentration of Co in the first redox cycle under reducing-acidic condition, due to lower pH values, and chemistry of sulfide-sulfate and Fe/Mn oxides. The phytoavailability of As and Co were higher than their potential mobility in the sediment phase, while the same trend was not discerned for Mo. The potential mobility and phytoavailability of As and Co were high under oxic-acidic conditions. The potential mobility and phytoavailability of Mo might be increased under oxic condition due to the dissolution of Fe and Mn oxides under lower pH conditions, especially in the BC treated soil. Application of such rice hull BC to soil might stimulate the release of As, Co, and Mo under flooding conditions, which might increase the environmental and health risks in such wetland ecosystems.
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25174. 题目: Residual micro organic pollutants and their biotoxicity of the effluent from the typical textile wastewater treatment plants at Pearl River Delta
文章编号: N18121304
期刊: Science of The Total Environment
作者: Feifei Xue, Bing Tang, Liying Bin, Jianwen Ye, Shaosong Huang, Fenglian Fu, Ping Li, Jiao Cui
更新时间: 2018-12-13
摘要: This work investigated the biotoxicity and the residual dissolved organic matter (DOM) of the effluents from nine typical full-scale textile plants located at Pearl River Delta (PRD) in Guangdong province, China. The fluorescence regional integration (FRI) analysis showed that the tryptophan-like (II), soluble microbial product-like (IV) and fulvic acid-like substances (III) were the dominant compounds in the DOM. The acute toxicity test showed toxic effects still remained in most textile effluents, which might attribute to the undegraded dyes or aromatic compounds. Combining with the results from multiple methods, it indicated that the selected nine textile wastewater treatment plants (tWWTPs) all contained some residual micro organic pollutants in their effluents, and the residual benzene-derived products or aromatic amines were probably the toxicity-causing substances. Both ozonization and membrane filtration were capable of further decreasing the content of residual DOM, but by comprehensively considering the effects of removing DOM and biotoxicity, membrane filtration was better than ozonization.
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25175. 题目: Microorganisms in ballast water: Disinfection, community dynamics, and implications for management
文章编号: N18121303
期刊: Science of The Total Environment
作者: Ole-Kristian Hess-Erga, Javier Moreno-Andrés, Øivind Enger, Olav Vadstein
更新时间: 2018-12-13
摘要: Increasing concerns have accelerated the development of international regulations and methods for ballast water management to limit the introduction of non-indigenous species. The transport of microorganisms with ballast water has received scientific attention in recent years. However, few studies have focused on the importance of organisms smaller than 10 μm in diameter. In this work, we review the effects of ballast water transport, disinfection, and the release of microorganisms on ecosystem processes with a special focus on heterotrophic bacteria. It is important to evaluate both direct and indirect effects of ballast water treatment systems, such as the generation of easily degradable substrates and the subsequent regrowth of heterotrophic microorganisms in ballast tanks. Disinfection of water can alter the composition of bacterial communities through selective recolonization in the ballast water or the recipient water, and thereby affects bacterial driven functions that are important for the marine food web. Dissolved organic matter quality and quantity and the ecosystem status of the treated water can also be affected by the disinfection method used. These side effects of disinfection should be further investigated in a broader context and in different scales (laboratory studies, large-scale facilities, and on the ships).
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25176. 题目: Stimulation of anaerobic organic matter decomposition by subsurface organic N addition in tundra soils
文章编号: N18121302
期刊: Soil Biology and Biochemistry
作者: Michael Philben, Jianqiu Zheng, Markus Bill, Jeffrey Heikoop, George Perkins, Ziming Yang, Stan D. Wullschleger, David E. Graham, Baohua Gu
更新时间: 2018-12-13
摘要: Increasing nitrogen (N) availability in Arctic soils could stimulate the growth of both plants and microorganisms by relieving the constraints of nutrient limitation. It was hypothesized that organic N addition to anoxic tundra soil would increase CH₄ production by stimulating the fermentation of labile substrates, which is considered the rate-limiting step in anaerobic C mineralization. We tested this hypothesis through both field and lab-based experiments. In the field experiment, we injected a solution of ¹³C- and ¹⁵N-labeled glutamate 35 cm belowground at a site near Nome on the Seward Peninsula, Alaska, and observed the resulting changes in porewater geochemistry and dissolved greenhouse gas concentrations. The concentration of free glutamate declined rapidly within hours of injection, and the ¹⁵N label was recovered almost exclusively as dissolved organic N within 62 h. These results indicate rapid microbial assimilation of the added N and transformation into novel organic compounds. We observed increasing concentrations of dissolved CH₄ and Fe(II), indicating rapid stimulation of methanogenesis and Fe(III) reduction. Low molecular weight organic acids such as acetate and propionate accumulated despite increasing consumption through anaerobic C mineralization. A laboratory soil column flow experiment using active layer soil collected from the same site further supported these findings. Glutamate recovery was low compared to a conservative bromide tracer, but concentrations of NO₃⁻ and NH₄⁺ remained low, consistent with microbial uptake of the added N. Similar to the field experiment, we observed both increasing Fe(II) and organic acid concentrations. Together, these results support our hypothesis of increased fermentation in response to organic N addition and suggest that increasing N availability could accelerate CH₄ production in tundra soils.
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25177. 题目: A novel waste activated sludge multistage utilization strategy for preparing carbon-based Fenton-like catalysts: catalytic performance assessment and micro-interfacial mechanisms
文章编号: N18121301
期刊: Water Research
作者: Jing Ai, Weijun Zhang, Guiying Liao, Feifei Chen, Dongsheng Wang
更新时间: 2018-12-13
摘要: Waste activated sludge (WAS) contains many anionic functional groups which can interact with heavy metal ions through electrostatic action and complexation reactions. The transition metals adsorbed in WAS can catalyze sludge pyrolysis in anaerobic conditions and improve structural properties of organic matter. In this work, a multistage WAS utilization process for preparing the carbon-based Fenton-like catalysis materials is proposed. More specifically, WAS is firstly used as an adsorbent for heavy metals (Cu and Ni) removal, and then complexes are converted into heterogeneous Fenton-like carbon-based catalysts through oxygen-free pyrolysis. The mechanisms of interactions between extracellular polymeric substances (EPS) and metals are investigated, and the physicochemical properties of sludge-based carbons (SBC) are comprehensively characterized using varies techniques. It is found that WAS is an excellent adsorbent for Cu and Ni removal, which is mainly due to the coordination and electrostatic interactions between EPS and heavy metals. Cu and Ni adsorbed in WAS significantly improved the porous structure of SBC. Both adsorption and catalytic oxidization of Cu/Ni-SBC contribute the removal of E2 in real wastewater. The E2 removal mechanism is explored by electron-spin resonance spectroscopy (ESR) analysis, and it is found that both of ^.O₂^- and ^.OH radicals are responsible for E2 degradation in Cu(II)-SBC-H₂O₂, while ^.O₂^- radicals contributes to E2 degradation in Ni(II)-SBC-H₂O₂ system, so the former performed better than the latter in total removal of E2. Besides, Cu(II) and Cu(I) are both formed in Cu(II)-SBC during the oxidation process, while only Ni(II) is found in the Ni(II)-SBC-H₂O₂ process, confirming that different catalytic oxidation reactions are occurred in the Cu(II)-SBC-H₂O₂ and Ni(II)-SBC-H₂O₂ processes. This study facilitates a great strategy to the sludge multi-stage circulating utilization and a better understanding about the role of the Cu/Ni existed in SBC during the estrogens removal process.
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25178. 题目: Understanding the behaviour of UV absorbance of natural waters upon chlorination using model compounds
文章编号: N18121222
期刊: Environmental Science: Water Research & Technology
作者: Nicolas Beauchamp, Caetano Dorea, Christine Beaulieu, Christian Bouchard, Manuel Rodriguez
更新时间: 2018-12-12
摘要: Differential UV absorbance (ΔA) is a promising indicator that could allow operators and utility managers to routinely monitor and manage disinfection by-product (DBP) concentrations without the limitations of regulatory sampling and analyses. So far, empirical relationships between DBP formation and ΔA at 272 nm have been proposed, but these relationships are known to be specific to the waters being analyzed. The objective of this study is qualitative rather than quantitative; it is to identify features of the spectra of simple compounds that are distinguishable in the spectra of natural water and relevant to predict DBP formation empirically. In order to meet this objective, compounds that could model the different components of natural organic matter (NOM) were chlorinated, and their UV spectra were collected at various reaction times, along with samples for DBP analyses. The same procedure was conducted on natural waters that were pretreated using coagulation and filtration. Results show that both diketone and phenolic moieties could be responsible for the initial decrease in absorbance observed around 270 nm, while the continuous gradual decrease that follows is attributable to phenolic structures. This gradual decrease is most notable around 250 nm, which means that ΔA at this wavelength might be more closely related to DBP formation than the usual ΔA at 272 nm. Other compounds such as carboxylic acids and amino acids do not seem to contribute significantly to trihalomethanes, haloacetic acids or ΔA in natural waters, although amino acids probably make up a significant proportion of the haloacetonitrile precursors.

25179. 题目: Using regional datasets of isotope geochemistry to resolve complex groundwater flow and formation connectivity in northeastern Alberta, Canada
文章编号: N18121221
期刊: Applied Geochemistry
作者: S.J. Birks, J.W. Fennell, J.J. Gibson, Y. Yi, M.C. Moncur, M. Brewster
更新时间: 2018-12-12
摘要: In the southern Athabasca Oil Sands (SAOS) Region, located in Alberta Canada, individual in-situ oil sands operators have conducted local geochemical and isotope groundwater studies to establish baseline characteristics and to improve understanding of the connectivity of water supply and disposal formations within individual leases. Canada's Oil Sands Innovation Alliance (COSIA) initiated this study to combine the data from these individual studies along with public information into a comprehensive unified dataset to evaluate conceptual models of regional groundwater flow and the degree of interaction and separation between important water supply and disposal aquifers. The unified dataset comprised over 293 groundwater samples from the main water source and disposal hydrostratigraphic units and included geochemical and isotopic tracers that can be used to identify sources (δ¹⁸O and δ²H) and age of water (³H) and associated solutes (¹⁴C-DIC, ³⁶Cl), as well as the sources of salinity and diagenetic processes (δ¹³C-DIC, δ³⁴S-SO₄, ⁸⁷Sr/⁸⁶Sr, δ¹¹B, δ³⁷Cl and δ⁸¹Br) and dissolved organics (δ¹³C-DOC). The TDS and stable isotope composition (δ¹⁸O and δ²H) of groundwater from several Cretaceous formations were used to identify three main mixing controls. i) Areas where locally recharged groundwater mixes with glaciogenic water were identified by lower δ¹⁸O and δ¹⁸O values, high TDS, Cl:Br and δ³⁴S-SO₄, ⁸⁷Sr/⁸⁶Sr, and δ³⁷Cl values consistent with dissolution of evaporites. These areas were situated where vertical pathways through otherwise competent formations are likely to occur. ii) Mixing with paleo-waters characterized by high TDS and higher δ¹⁸O and δ²H signatures indicating groundwater recharged under warmer climate periods and/or evaporative enrichment were identified in the south, and southwestern portions of the study area. The presence of these paleo-waters indicate slow-moving groundwater zones with limited lateral and vertical connectivity. iii) Areas with potential connectivity to shallow aquifers were identified by their lower TDS values, modern meteoric δ¹⁸O and δ²H signatures, HCO₃ type waters, and δ³⁴S-SO₄ and ⁸⁷Sr/⁸⁶Sr signatures, consistent with weathering of shallow aquifer material. Geochemical and isotopic indicators that suggest that in areas where the Colorado Group aquitard is thin or absent there is greater connectivity between the Grand Rapids Formation and the shallower aquifers. Interpretation of the new unified dataset has improved understanding of the extent that glacial recharge had on Devonian aquifers, and overlying Cretaceous formations, and identified zones with relatively stagnant groundwater flow, both of which have implications for regional groundwater resource development, monitoring and potential wastewater disposal.

25180. 题目: Effects of different types of extracellular polysaccharides isolated from cyanobacterial blooms on the colony formation of unicellular Microcystis aeruginosa
文章编号: N18121220
期刊: Environmental Science and Pollution Research
作者: Ken Omori, Tania Datta, Yoshimasa Amano, Motoi Machida
更新时间: 2018-12-12
摘要: In this study, two types of extracellular polysaccharides (EPS), namely, mixed EPS (MX-EPS) and tightly bound EPS (TB-EPS), were extracted from cyanobacterial blooms using different methods. To evaluate their compositional differences, elemental composition, FTIR, and TG/DTA profile were measured for both EPS samples. Following that, unicellular Microcystis aeruginosa was cultured in a medium containing EPS, Ca²⁺ ion, and Mg²⁺ ion, and the effect of each type of EPS on the colony formation of M. aeruginosa was examined. Results showed that TB-EPS had more carboxy groups than MX-EPS, and that the TB-EPS medium contained Ca²⁺ and Mg²⁺ ions. These cations were not detected in the MX-EPS medium. During the colony formation experiment, colonies were observed when Ca²⁺ and Mg²⁺ ions were present at 250 mg/L concentration each. In addition, colony density increased when TB-EPS was added, compared to that of MX-EPS. Colonies were also observed in the medium containing only TB-EPS (100 mg/L), indicating that M. aeruginosa can form colonies using Ca²⁺ ion present in TB-EPS. During the MX-EPS extraction, Ca²⁺ ion chelated with EDTA was removed during ethanol precipitation. Therefore, the extraction protocol followed for TB-EPS was better than that of MX-EPS for maintaining Ca²⁺ ions, and thereby maintaining an EPS composition that enables for colony formation.