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23521. 题目: Photocatalytic degradation of trace carbamazepine in river water under solar irradiation
文章编号: N19041501
期刊: Journal of Environmental Management
作者: Longli Bo, Heng Liu, Haixia Han
更新时间: 2019-04-15
摘要: An interesting ZnIn₂S₄/TiO₂ composite catalyst was prepared by a hydrothermal method and thoroughly characterized. The photocatalytic degradation of trace carbamazepine (CBZ) in two river waters was primarily investigated through a batch experiment under solar irradiation, and the effects of dissolved organic matter (DOM), inorganic salt (IS), suspended solids (SS) and ultraviolet (UV) on CBZ degradation were researched. The influential degree was DOM ≈ IS » SS and CBZ with an initial concentration of 100 μg/L in the Bahe River water was completely degraded under a catalyst dosage of 75 mg/L and solar irradiation of 240 min. Compared with direct photolysis, the reaction rate constant enhanced 45 times and the half-life reduced to 1/82 in photocatalysis after the removal of all SS, IS and DOM. A certain adsorption capacity of composite catalyst with a specific surface area of 91.9 m²/g and a strong interaction between TiO₂ and ZnIn₂S₄ effectively improved the photocatalytic degradation of CBZ. The increase of light intensity was confirmed to be of benefit to CBZ photocatalysis. Most of CBZ was degraded by visible light and UV effect was negligible. Although photo-etching and acidic corrosion by course products had negative effect on ZnIn₂S₄/TiO₂, the removal of CBZ was mainly kept at 86% after five times usage of the catalyst.

23522. 题目: Relevance of dissolved organic matter generated from green manuring of Chinese milk vetch in relation to water-soluble cadmium
文章编号: N19041412
期刊: Environmental Science and Pollution Research
作者: Jie Xie, Aiqin Dong, Jia Liu, Jinping Su, Po Hu, Changxu Xu, Jingrui Chen, Qitang Wu
更新时间: 2019-04-14
摘要: Dissolved organic matter (DOM) can become a carrier of soil contaminants. Therefore, an understanding of the evolution and characteristics of DOM produced by Chinese milk vetch during green manuring is crucial. In this study, DOM solutions from 28 days’ manuring with three different organic materials were characterized using three-dimensional fluorescence excitation–emission matrix (3D-EEM) with parallel factor (PARAFAC) analysis, and ultraviolet–visible spectroscopy. With the green manuring milk vetch at flowering period (MVFP), the DOC and water-soluble cadmium (WS-Cd) in soil solution reached 1875 mg/l and 2.64 μg/l, respectively, on day 6 after manuring. The PARAFAC analysis modeled three components: protein-like (tryptophan) and two humic-like components (humic acid and fulvic acid); DOM produced by MVFP was primarily protein-like during the early stage of decomposition. The aromaticity and molecular weight of DOM in the MVFP treatment was lower than in the other treatments, which could promote the release of soil particle-adsorbed Cd to soil solution. Principal components analysis showed that aromaticity was the main factor affecting Cd solubility, and the negative linear correlation of aromaticity with WS-Cd reached 0.4827. The results of this study supported the idea that manuring with MVFP might accelerate Cd infiltration to deep soil with water under gravity.

23523. 题目: Dynamics of organic matter in the Seine Estuary (France): Bulk and structural approaches
文章编号: N19041411
期刊: Marine Chemistry
作者: Alexandre Thibault, Sylvie Derenne, Edith Parlanti, Christelle Anquetil, Mahaut Sourzac, Hélène Budzinski, Laura Fuster, Anniet Laverman, Céline Roose-Amsaleg, Eric Viollier, Arnaud Huguet
更新时间: 2019-04-14
摘要: Estuaries are important ecosystems from environmental and economical point of views and are the place of numerous transformations of organic matter (OM) during the transfer from land to the ocean. The dynamics of OM in estuarine systems is complex and was only rarely investigated at the structural or molecular level, even though OM transformation in the estuarine aquatic and sediment compartments involves processes taking place at this level. The aim of this study was to constrain the sources and fate of the OM in the Seine Estuary, one of the largest estuaries in France. The spatiotemporal dynamics of the OM along the estuary was investigated by comparing the bulk (elemental and isotopic composition) and structural (solid state ¹³C nuclear magnetic resonance) features of the different pools of OM – dissolved OM (DOM), particulate OM (POM) and sediment OM collected during five sampling campaigns. Reverse osmosis coupled with electrodialysis (RO/ED) was used to concentrate and isolate DOM, yielding an average organic carbon recovery of 59% (± 15%). RO/ED had a limited effect on DOM properties, DOM showing >75% of similarity with initial estuarine samples based on 3D fluorescence measurements. Bulk and structural analyses of DOM, POM and sedimentary OM showed that OM is mainly of aquatic origin in the Seine Estuary, regardless the OM pool. Nevertheless, significant differences in chemical composition between the three OM pools were observed: higher C/N ratios, carbohydrate, lipid and protein content as well as lower char and lignin contents in DOM than in the other two compartments. Spatial variations of OM properties, for POM and to a lesser extent DOM, were observed along the Seine Estuary based on δ¹³C and Δ¹⁴C analyses and ¹³C NMR-derived protein and lipid contents, showing the transition from a riverine to a marine-dominated system. In the mixing zone of the estuary, the Δ¹⁴C composition of the sediment OM was related to the tidal strength, with strong tides leading to the resuspension of recent sediment OM and weak tides allowing the deposition of recent aquatic OM. Altogether, the combination of bulk and structural techniques showed that the Seine Estuary OM quality is mainly related to the compartment (DOM/POM/sediment) and to a lesser extent to the sampling zone (upstream/maximum turbidity zone/downstream). The approach proposed for the characterization of the Seine Estuary OM could be applied to other estuaries, allowing a better understanding of the complex OM dynamics in such ecosystems.

23524. 题目: A Bayesian statistical approach to inferring particle dynamics from in-situ pump POC and chloropigment data from the Mediterranean Sea
文章编号: N19041410
期刊: Marine Chemistry
作者: Wei-Lei Wang, Cindy Lee, cois W. Primeau Fran
更新时间: 2019-04-14
摘要: Concentrations of chloropigments and particulate organic carbon (POC) in large-volume in-situ pump samples from the Mediterranean Sea were used to estimate rate constants of processes that control the fate of particles, and specifically chloropigments, in the water column. Here we introduce a Bayesian statistical inversion method that combines the data with a new box model and has the capacity to infer rate constants for POC respiration/dissolution, chlorophyll and pheopigment degradation, and particle aggregation and disaggregation. We use first-order kinetics to model disaggregation, and use both first-order and second-order kinetics to model aggregation. Using these methods, the estimated small-particle (1–70 μm) POC respiration rate constant was 2.44_−1.00^+1.69 yr⁻¹ (0.41 yr). The estimated disaggregation and second-order aggregation rate constants were 85.6_−36.4^+63.4 yr⁻¹ (1.17×10⁻² yr) and 2.78_−1.17^+2.01 μM⁻¹ yr⁻¹, respectively. Using the optimal rate constants and the corresponding particle concentrations, aggregation is ∼1.3 and disaggregation ∼4.2 times faster than the small-size POC dissolution rate, which indicates that aggregation and disaggregation were dominant processes at the time of sampling. More importantly, by comparing our results with those of previous studies, we conclude that sampling methods have less influence than tracers themselves on inferring particle dynamic rate constants. We previously introduced a somewhat similar approach to modeling SV sediment trap data, but large volume pumps are a much more common sample collection method in oceanographic surveys than SV sediment traps, and thus our new model should have a wider applicability.

23525. 题目: A multiproxy study of past environmental changes in the Sea of Okhotsk during the last 1.5 Ma
文章编号: N19041409
期刊: Organic Geochemistry
作者: Julie Lattaud, Li Lo, Christian Zeeden, Ya-Jun Liu, Sheng-Rong Song, Marcel T.J. van der Meer, Jaap S. Sinninghe Damsté, Stefan Schouten
更新时间: 2019-04-14
摘要: Long-chain diols have been detected in a wide range of environments and have been used to reconstruct past environmental changes, however only a few long-term records exist to date. Here we reconstructed past environmental changes in the central Sea of Okhotsk over the last 1.5 million years, covering the Mid-Pleistocene Transition (MPT). Sea surface temperatures (SST) reconstructed using the Long-Chain Diol Index (LDI) reflects glacial/interglacial changes. However, when compared with other organic paleothermometers (U^k’₃₇ and TEX^L₈₆) the LDI-SST is lower during interglacials and similar or higher during glacials, possibly suggesting a shift of diol production season during interglacials. The LDI-SST does not change in periodicity around the MPT as observed for the TEX^L₈₆, likely due to this seasonal shift. Diatom productivity, as recorded by 1,14-diols and biogenic opal content, increased during the main deglaciations with a succession from Proboscia diatoms to diatoms with a more heavily silicified shell, confirming that primary productivity in the central Sea of Okhotsk is driven by sea-ice progress and retreat. In contrast to the LDI-SST, the 1,14-diols record shows a change in periodicity around the MPT from 41- to 100-kyr cycle, suggesting an influence of orbital parameters on diatom productivity. In the central Sea of Okhotsk, the relative amount of C₃₂ 1,15-diol (F_{C32 1,15}), a proxy for riverine input, correlates with sea-level change with more riverine-derived material reaching the core site when the Amur River mouth is closer at lower sea-levels. In agreement, F_{C32 1,15} shows a change in periodicity during the MPT, with the appearance of a 100-kyr cycle. Our results show that the long chain diols can provide important paleoceanographic information in subpolar environments over long time scales, but that temperature reconstructions can be severely impacted by changes in seasonality.

23526. 题目: The influence of biochar particle size and concentration on bulk density and maximum water holding capacity of sandy vs sandy loam soil in a column experiment
文章编号: N19041408
期刊: Geoderma
作者: Frank G.A. Verheijen, Anna Zhuravel, Flávio C. Silva, António Amaro, Meni Ben-Hur, Jan Jacob Keizer
更新时间: 2019-04-14
摘要: Biochar application to agricultural soils has been proposed as a way to increase crop production by improving soil chemical and physical properties. Liming potential and improved nutrient exchange on biochar surfaces are the most reported mechanisms. Wherever crops experience drought stress, improvements in soil water holding capacity (WHC) might also be an important mechanism. However, reported effects on soil structure and WHC are mixed. Therefore, we studied the effects of biochar on soil bulk density (BD) and WHC in a laboratory column study using two agricultural soils from Portugal: a sandy and a sandy loam soil. Mixed woody feedstock was pyrolysed at 620 °C, creating a wettable biochar that was used unsorted as well as sieved into large (2–4 mm) and small (0.05–1.00 mm) particles, mixed into the soils at 1, 5, 10 and 20% (by volume), and incubated for 10 days at field capacity to allow aggregation. Soil samples were analysed for BD and WHC using soil columns.We found biochar to decrease soil BD and increase maximum WHC, expressed as gravity-drained equilibrium water content, for both soils. The sandy soil was more responsive with significant effects at the lowest application rate (1%), while the sandy loam soil started to show significant effects at 5% biochar. Small biochar particles reduced the BD of sandy soil more, while large biochar particles caused a greater reduction in the BD of the sandy loam soil. The effect of biochar particle size on WHC was less clear, except for small particles at 20% volumetric concentration, which showed a 60% increase in gravimetric WHC. When expressed as total soil water storage (SWS), 20% biochar incorporation to 15 cm depth would increase the total SWS of sandy soil from 0.56 mm (control) to 0.83–0.91 (mm), and of the sandy loam soil from 0.56 to 0.79–0.96 (mm), depending on biochar particle size. Our results suggest that biochar particle sizes can be used to achieve specific effects in soils, while mechanisms and trade-offs (agro-economic and environmental) need further exploration.
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23527. 题目: Earthworms regulate ability of biochar to mitigate CO₂ and N₂O emissions from a tropical soil
文章编号: N19041407
期刊: Applied Soil Ecology
作者: Nictor Namoi, David Pelster, Todd S. Rosenstock, Lukelysia Mwangi, Solomon Kamau, Paul Mutuo, Edmundo Barrios
更新时间: 2019-04-14
摘要: Soils account for >80% and 20% of the total agricultural N₂O and CO₂ emissions respectively. Soil management activities that target improved soil health, such as enhancing earthworm activity, may also stimulate further emissions of CO₂ and N₂O. One recommended strategy for mitigating these soil emissions is biochar amendment. However greater clarity on the interaction between earthworm activity and biochar, and subsequent impact on CO₂ and N₂O are needed to evaluate the environmental impacts of management practice. We measured N₂O and CO₂ emissions from a kaolinitic Acrisol in the presence or absence of earthworms, with and without application of two different biochars in a microcosm study. The two biochars were derived from indigenous trees; Zanthoxylum gilletii and Croton megalocarpus, and were tested at three application rates of 5 Mg ha⁻¹, 10 Mg ha⁻¹ and 25 Mg ha⁻¹. Emissions of CO₂ and N₂O increased by 26% and 72% respectively in the presence of earthworms. In microcosms with biochar and earthworms however, emissions depended on type of biochar and rate of application. With C. megalocarpus, CO₂ emission increased with increasing rates of biochar application with 25 Mg ha⁻¹ resulting in higher CO₂ fluxes compared to no-biochar control (p = 0.002), while no change was observed with Z. gilletii at the same rate. Nitrous oxide emissions were suppressed at 25 Mg ha⁻¹ for both C. megalocarpus (p = 0.009) and Z. gilletii (p = 0.011). Reduction in N₂O flux was however not consistent across biochar types. No change in N₂O was observed with 5 Mg ha⁻¹ and 10 Mg ha⁻¹of C. megalocarpus. Biochar from Z. gilletii at 5 Mg ha⁻¹ however led to increase in N₂O emissions (p < 0.001). Our findings suggest that earthworms may moderate the effect of biochar, with suppression of N₂O emissions occurring at only high biochar application rates, which may occur at the cost of increasing CO₂ emissions. These findings contrast with biochar suppressing effect on N₂O emissions even at moderate biochar rates of (10 Mg ha⁻¹) when in absence of earthworms, an outcome typical of many laboratory experiments. These findings highlight new interactions among application rate, source of biochar (and hence properties) and earthworms.

23528. 题目: Effects of dissolved humic acid on fluoroquinolones sorption and retention to kaolinite
文章编号: N19041406
期刊: Ecotoxicology and Environmental Safety
作者: Yandan Li, Erping Bi, Honghan Chen
更新时间: 2019-04-14
摘要: Fluoroquinolones (FQs) are widely used in human and veterinary medicaments, and as such are ubiquitous environmental contaminants. Dissolved organic matter (DOM) is widely distributed in natural water and sediment and dissolved humic acid (DHA) is a major component of DOM. The coexistence of DHA might influence the sorption, migration and transformation of FQs, thus determining their environmental fate. In this study, the interaction of DHA and ofloxacin (OFL)/flumequine (FLU) was evaluated using dialysis-bag assays. The sorption of OFL and FLU to kaolinite in the presence of DHA under different pH conditions was investigated. The results revealed that the binding affinities of FQs to DHA were weakened with increasing pH from 4.0 to 10.0 due to the increased negative charge of DHA and subsequent electrostatic repulsion. Sorption experiments indicated that co-precipitation was an important mechanism for OFL/FLU removal from the aqueous phase under acidic conditions. At pH 7.0, the affinity of OFL-DHA/FLU-DHA to kaolinite was weaker than that of OFL/FLU thus suppressed its sorption. At pH 9.5, the affinity of OFL-DHA to kaolinite was stronger than that of OFL and consequently promoted its sorption, but there was no observed effect of DHA on FLU sorption. During desorption, DHA could bind to OFL/FLU and promote its desorption from kaolinite at neutral pH. In binary solute systems of OFL and FLU, OFL was a more effective competitor for the sorption sites of kaolinite than FLU.
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23529. 题目: Accurately quantifying the reductive capacity of microbial extracellular polymeric substance by mediated electrochemical oxidation method
文章编号: N19041405
期刊: Science of The Total Environment
作者: Zhi-Qi Lin, Wei Shao, Juan Xu, Guo-Ping Sheng
更新时间: 2019-04-14
摘要: The reductive capacity of microbial extracellular polymeric substances (EPS) plays important roles in environmental processes involved in heavy metal detoxification and organic contaminant degradation. However, the crucial parameter to evaluate the reductive capacity of EPS, electron donating capacity (EDC) lacks a quantitative approach. In this study, a novel mediated electrochemical oxidation (MEO) method was developed to investigate the EDCs of microbial EPS extracted from Shewanella oneidensis MR-1 (S. oneidensis MR-1), Escherichia coli (E. coli) and activated sludge. The results indicate that the MEO approach rapidly and accurately quantifies the EDCs of microbial EPS. S. oneidensis MR-1 EPS possessed the highest EDC value ascribed to their specific redox proteins components. EDCs of S. oneidensis MR-1 EPS were dependent on measurement conditions and increased with growing solution pH and applied potential. EDCs of S. oneidensis MR-1 EPS were depleted gradually during the redox reaction with irreversible oxidation of EPS. The reductive property of microbial EPS was accurately evaluated by quantifying the EDCs of EPS using the MEO approach, as well as their potential in environmental remediation.
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23530. 题目: Effect of oxidation-induced aging on the adsorption and co-adsorption of tetracycline and Cu²⁺ onto biochar
文章编号: N19041404
期刊: Science of The Total Environment
作者: Tiantian Nie, Pulin Hao, Zhendong Zhao, Wenjun Zhou, Lizhong Zhu
更新时间: 2019-04-14
摘要: The bamboo biochars pyrolyzed at 400 °C and 600 °C (BC400 and BC600) were modified by hydrogen peroxide (H₂O₂) to obtain the oxidized biochars. Biochar stability and the effect of oxidation treatment on the adsorption and co-adsorption of tetracycline (TC) and Cu²⁺ onto biochars were investigated. The calculated carbon loss of biochars after oxidation treatment indicated that BC600 presented higher carbon stability than BC400 due to the condensed aromatic structure of biochar. Moreover, oxidation treatment introduced O-containing functional groups on biochar surface, but destructed the aromatic structures of oxidized biochars, which in turn affected the adsorption capacity of biochars for TC and Cu²⁺. Oxidation treatment obviously enhanced the adsorption of TC and Cu²⁺ onto BC400 owing to the increase of O-containing functional groups, but significantly decreased TC and Cu²⁺ adsorption onto BC600 because of the decreased π-π dispersive forces between biochar and adsorbate. The promotion effect of Cu²⁺ on TC adsorption onto BC400 changed into inhibition effect after chemical oxidation owing to the pore blockage. However, the promotion degree of Cu²⁺ for TC adsorption onto BC600 was enhanced through oxidation treatment due to electrostatic attraction and complexation. Meanwhile, oxidation treatment reduced the inhibition degrees of TC for Cu²⁺ adsorption onto biochars, which was attributed to the increased amount of electron-rich groups. The results are helpful for the application of biochars in the soils remediation.
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23531. 题目: Transformation and fate of dissolved organic nitrogen in drinking water supply system: A full scale case study from Yixing, China
文章编号: N19041403
期刊: Science of The Total Environment
作者: Yang Li, Hang Xu, Chen He, Zhen Shen, Wei Chen, Li Gao, Chenshuo Lin, Tao Lin, Chunhui Lu, Quan Shi, Jian Luo, Wei Wang
更新时间: 2019-04-14
摘要: The transformation of dissolved organic nitrogen (DON) in the drinking water treatment plants could be closely associated with nitrogenous disinfection by-product (N-DBP) formation. In this study, we have assessed the molecular transformation of DON and its impact on N-DBP formation in a full scale drinking water treatment plant. Based on the result of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis, DON compounds with low molecular weight (<1 kDa) were classified as CHON, CHON₂ and CHON₃ according to the number of nitrogen atoms. Via the analytical window of van Krevelen diagrams, we found that the molecular structural features of CHON, CHON₂ and CHON₃ were not altered before the chlorination process. In detail, the CHON₂ and CHON₃ compositions were concentrated on the regions assigned to a lignin-structure while CHON compositions were also distributed in other compounds including proteins, carbohydrates and tannin. Furthermore, CHON formation was more difficult to be removed before the V-filter process. For N-DBP, chlorine-containing DON (Cl-DON) composition was likely to be removed through flocculation and sedimentation processes, whereas N-nitrosamine compounds were removed in V-filter and biological activated carbon filter processes. The health risks of aromatic structure N-nitrosamines due to the pre-chlorination of the raw water should be further studied.
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23532. 题目: The kinetics, thermodynamics and mineral crystallography of CaCO₃ precipitation by dissolved organic matter and salinity
文章编号: N19041402
期刊: Science of The Total Environment
作者: Daoyong Zhang, Qinghua Lin, Nana Xue, Pengfeng Zhu, Ziyan Wang, Wenyi Wang, Qing Ji, Lingfeng Dong, Kaifang Yan, Jingyi Wu, Xiangliang Pan
更新时间: 2019-04-14
摘要: Calcium carbonate (CaCO₃) precipitation is an important geochemical process. In the estuary zone and some arid shallow lakes, DOM (dissolved organic matter) and salinity are two frequent changing factors that may affect CaCO₃ precipitation. The joint effect of DOM and salinity on CaCO₃ precipitation kinetics and thermodynamics are still unclear. In this study, effects of DOM on CaCO₃ precipitation process at 0.5‰ and 70‰ salinity were investigated by QCM (Quartz Crystal Microbalance) technique, real-time pH measurement and single-injection nanoliter ITC (isothermal titration calorimetry). The mineral crystallography was analyzed by SEM-EDS. Both DOM and salinity had inhibitory effect on CaCO₃ precipitation. DOM had more pronounced inhibitory effect on CaCO₃ precipitation at lower salinity. Regardless of DOM, 70‰ salinity inhibited CaCO₃ precipitation >0.5‰ salinity. The CaCO₃ precipitation kinetics followed the first-order kinetic model and the adhesion kinetics of the instantaneous nucleation and crystal growth stage could be well described by the exponential function. CaCO₃ precipitation was an endothermic process and high salinity strongly hindered CaCO₃ precipitation. The effect of DOM on the absorbed heat was significant at 0.5‰ salinity. At 70‰ salinity, regardless of the effect of DOM, CaCO₃ precipitation rate was greatly slowed down because it needed much more heat. CaCO₃ minerals were dominated by rhombohedral calcite while CaCO₃ minerals were mainly shaped as spherical vaterite at 0.5‰ salinity and rhombohedral calcite at 70‰ salinity. The crystal phase changed during CaCO₃ precipitation at 0.5‰ salinity. In conclusion, the presence of DOM had substantial impact on the micrograph of the CaCO₃ minerals. The percentage of flawed crystals with rough surface increased significantly with increased DOM concentration.
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23533. 题目: Mercury and methylmercury concentrations, sources and distribution in submarine canyon sediments (Capbreton, SW France): Implications for the net methylmercury production
文章编号: N19041401
期刊: Science of The Total Environment
作者: Alyssa Azaroff, Emmanuel Tessier, Jonathan Deborde, Rémy Guyoneaud, Mathilde Monperrus
更新时间: 2019-04-14
摘要: Submarine canyons are important stocks of commercial interest fish, whose consumption is one of the main monomethymercury (MeHg) exposure to humans. Currently, biogeochemistry of mercury in those biologically productive system is unknown. In this work, inorganic mercury (Hg(II)) and organic mercury (MeHg) distributions were measured in sedimentary accumulative zones (slopes and terraces) against adjacent continental shelf sediments. Hg compound concentrations in these sediments show a huge range of concentrations (Hg(II) ranging from 18 to 973 ng g⁻¹ and MeHg ranging from 0.07 to 2.03 ng g⁻¹) exhibiting factors 50 and 20 fold, respectively. Higher values of mercury compounds were observed in canyon locations suggesting a high accumulation of mercury associated with higher values of clay fraction and organic matter content. The reactivity of mercury was investigated in sediment of three locations along Capbreton submarine canyon axis using slurry incubations experiments and isotopic tracers. Specific methylation and demethylation rate constants (k_M and k_D) were calculated. Results clearly showed that MeHg concentrations in these sediments are controlled by competing and simultaneous methylation and demethylation reactions mainly mediated by biotic process. Mercury reactivity was found higher in coastal stations compared to the offshore station due to more labile organic matter which may stimulate microbial activities. However, higher net MeHg production was estimated for the offshore station due to high Hg(II) concentrations suggesting a potential MeHg source for such marine environments.
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23534. 题目: Humic Substances Facilitate Arsenic Reduction and Release in Flooded Paddy Soil
文章编号: N19041309
期刊: Environmental Science & Technology
作者: Jiangtao Qiao, Xiaomin Li, Fangbai Li, Tongxu Liu, Lily Y. Young, Weilin Huang, Ke Sun, Hui Tong, Min Hu
更新时间: 2019-04-13
摘要: Organic matter is important for controlling arsenic reduction and release under anoxic conditions. Humic substances (HS) represent an important fraction of natural organic matter, yet the manner in which HS affect arsenic transformation in flooded paddy soil has not been thoroughly elucidated. In this study, anaerobic microcosms were established with arsenic-contaminated paddy soil and amended with three extracted humic fractions (fulvic acid, FA; humic acid, HA; and humin, HM). The HS substantially enhanced the extent of arsenic reduction and release in the order FA > HA > HM. It was confirmed that microbially reduced HS acted as an electron shuttle to promote arsenate reduction. HS, particularly FA, provided labile carbon to stimulate microbial activity and increase the relative abundances of Azoarcus, Anaeromyxobacter, and Pseudomonas, all of which may be involved in the reduction of HS, Fe(III), and arsenate. HS also increased the abundance of transcripts for an arsenate-respiring gene (arrA) and overall transcription in arsenate-respiring Geobacter spp. The increase in both abundances lagged behind the increases in dissolved arsenate levels. These results help to elucidate the pathways of arsenic reduction and release in the presence of HS in flooded paddy soil.
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23535. 题目: Twenty-five years of observations of soil organic carbon in Swiss croplands showing stability overall but with some divergent trends
文章编号: N19041308
期刊: Environmental Monitoring and Assessment
作者: Andreas Gubler, Daniel Wächter, Peter Schwab, Michael Müller, Armin Keller
更新时间: 2019-04-13
摘要: The temporal evolution of soil organic carbon (SOC) is of major importance given its status as a key parameter in many soil functions. Furthermore, soils constitute an important reservoir of carbon in our environment. In light of climate change, consistent SOC data over extended periods in combination with information on agricultural management are much required, but still scarce. We report SOC changes in the topsoil (0–20 cm) of Swiss cropland measured at well-defined monitoring sites resampled every 5 years from 1990 to 2014 by the Swiss Soil Monitoring Network NABO using consistent sampling protocols and quality assurance. Data on agricultural management practices were retrieved from farmers. Overall, SOC remained stable for the ensemble of monitoring sites, although increasing and decreasing trends were observed for individual sites, ranging from − 11 to + 16% relative change per decade. Changes in the agricultural management of cropland triggered substantial changes in SOC contents for some sites. Moreover, sites with a low ratio of SOC/clay (< 0.1) generally showed more positive trends than sites with higher ratios. We presume that SOC was either at or near steady state, given the consistency of management practices over the last few decades. Finally, our study provides insights into the uncertainties related to (real-world) SOC monitoring and underlines the relevance of short-term SOC variations that could hamper the detection of long-term trends. The minimum detectable change (MDC) by the applied monitoring scheme is estimated at 0.35% per year, in relative terms.

23536. 题目: Dewaterability enhancement and heavy metals immobilization by pig manure biochar addition during hydrothermal treatment of sewage sludge
文章编号: N19041307
期刊: Environmental Science and Pollution Research
作者: Shengyu Xie, Guangwei Yu, Chunxing Li, Futian You, Jie Li, Renqiang Tian, Gang Wang, Yin Wang
更新时间: 2019-04-13
摘要: Hydrothermal treatment (HTT) of sewage sludge (SS) with pig manure biochar (PMB) addition at 160–200 °C was conducted in this study. The effects of PMB addition on the dewaterability of SS and the speciation evolution, leaching toxicity, and potential ecological risk of heavy metals were investigated. The results showed that the solid contents of the filter cakes after adding PMB increased from 20.24%, 24.03%, and 28.69% to 21.57%, 27.69%, and 32.91% at 160, 180, and 200 °C, respectively, compared with traditional HTT of SS. Furthermore, PMB could reduce the bioavailable fractions of Cr, Ni, As, and Cd in the filter cakes obtained at 160 and 180 °C compared with the theoretical value. The leaching toxicity of heavy metals in the filter cakes after adding PMB decreased significantly at 160 and 180 °C and the potential ecological risk index (RI) declined from 62.13 and 44.83 to 55.93 and 42.11, respectively. The obtained filter cake had low potential ecological risk when used in the environment. The mechanisms on the improvement of the dewaterability and heavy metals immobilization were related that PMB acted as the skeleton builder providing the outflow path for free water and implanting heavy metals into SS structure. And the optimal results were obtained at 180 °C during HTT of SS with PMB addition. This work provides a novel and effective method for the treatment of SS.

23537. 题目: Recent advances in biochar-based catalysts: Properties, applications and mechanisms for pollution remediation
文章编号: N19041306
期刊: Chemical Engineering Journal
作者: Rong-Zhong Wang, Dan-Lian Huang, Yun-Guo Liu, Chen Zhang, Cui Lai, Xin Wang, Guang-Ming Zeng, Xiao-Min Gong, Abing Duan, Qing Zhang, Piao Xu
更新时间: 2019-04-13
摘要: Biochar (BC) is one of the most remarkable materials for environmental remediation. An increasing number of researchers have attempted to utilize BC as a catalyst to generate reactive oxygen species (ROS) and sulfate radicals. This work focuses on the development and progress of BC-based catalysts in different systems, including redox systems, Fenton-like systems, sonocatalytic systems and photocatalytic systems. Most importantly, the catalytic performance and mechanism of different types of BC-based catalysts are thoroughly investigated. Furthermore, the applications of BC-based catalysts in wastewater, sediments, soil and gas are presented. Special attention is paid to the factors involved in the generation of ROS and sulfate radicals, such as oxygen-containing functional groups (OFGs), persistent free radicals (PFRs) and redox properties. The generation processes of ROS and sulfate radicals are presented in detail. And the removal pathways of three mechanisms are elaborated. Furthermore, research in this field is still at an early stage, and many improvements are required before the technology can be efficiently scaled up and put into practice. This review enriches the knowledge about the generation processes of ROS and sulfate radicals by BC-based catalysts and improves the understanding of the catalytic performance and catalytic mechanism of BC-based catalysts for pollutants.
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23538. 题目: Coadsorption of tetracycline and copper(II) onto struvite loaded zeolite – An environmentally friendly product recovered from swine biogas slurry
文章编号: N19041305
期刊: Chemical Engineering Journal
作者: Yuan Wang, Xuejiang Wang, Jing Li, Yuan Li, Siqing Xia, Jianfu Zhao, Tashu Mengist Minale, Zaoli Gu
更新时间: 2019-04-13
摘要: In this study, an environmentally friendly struvite-loaded zeolite (S-NZ), prepared by nutrient recovery from swine biogas slurry, was used in the simultaneous removal of Cu (II) and tetracycline (TC) in solution for the first time. The adsorption behavior was systematically studied by accessing solution pH, kinetics, equilibriums in sole and binary systems. The results showed that the adsorption of Cu(II) and TC was fast and remarkably affected by solution pH due to pH-dependent speciation of adsorbates and the zeta potential of the S-NZ. Adsorption isotherms of TC and Cu(II) in binary system were well fitted by the Langmuir model and competitive Langmuir model, with the maximum adsorption capacities of 197.53 mmol TC/kg and 379.42 mmol Cu(II)/kg, respectively. The removal of TC could be significantly enhanced when Cu(II) coexisted, but not vice versa. Besides, the Coulombic interaction in the binary system at different pH was further supported by calculating relative charge distribution over the entire Cu(II)-TC complex and postulating the orientation of Cu-TC complex on the surface of S-NZ. Moreover, dissolved organic matter (DOM) impeded the adsorption of TC and Cu (II) onto S-NZ because of its formation of complex with Cu(II) and TC. This study shows new guidelines and useful methods for nitrogen and phosphorus recovery from livestock and poultry biogas slurry as well as its application in heavy metals and antibiotic pollution control.

23539. 题目: Effects of surface-modified biochars and activated carbon on the transformation of soil inorganic nitrogen and growth of maize under chromium stress
文章编号: N19041304
期刊: Chemosphere
作者: Yuen Zhu, Hua Li, Yi Wu, Xin-An Yin, Guixiang Zhang
更新时间: 2019-04-13
摘要: Elevated chromium (Cr) level is challenging agricultural production and affecting soil biochemical process. This study evaluated the effect of amendments including surface-modified biochars (HBC: acid washing, Fe(III)-HBC: ferric iron loading, nZVI-HBC: nanoscale zero-valent iron loading) and activated carbon on hexavalent chromium (Cr(VI)) removal in soil and on N cycling enzyme activities, transformation of soil inorganic nitrogen, and growth of maize under Cr stress. The results showed that amendments increased Cr(VI) removal by 72.9%–96.34% at three levels of spiked Cr(VI) (low: 125 mg kg⁻¹, moderate: 250 mg kg⁻¹, high: 500 mg kg⁻¹). Under low Cr stress, amendments generally significantly decreased urease and nitrite reductase activities but increased nitrate reductase activity (p < 0.05). The NH₄⁺-N content had a significant positive correlation with urease activity (p < 0.01), while both NO₂⁻-N and NO₃⁻-N were absent correlations with N cycling enzyme studied. Amendments decreased NH₄⁺-N/NO₃⁻-N ratio under low Cr stress but increased it under moderate Cr stress, although the difference was not significant. Under high Cr stress, only Fe(III)-HBC significantly increased NH₄⁺-N/NO₃⁻-N ratio (p < 0.05). The decrease and increase of NH₄⁺-N/NO₃⁻-N ratios indicate the enhancement of nitrification and denitrification, respectively. The increase in Cr(VI) removal by amendments contributed to the increase in the migration of NO₃⁻-N from roots to shoots. Amendments (except for nZVI-HBC in soil under low Cr stress) increased maize height by 20%–59%. Under low Cr stress, however, nZVI-HBC significantly decreased maize height by 65% (p < 0.05), indicating the toxic effect of nZVI on maize growth overwhelmed low Cr stress.
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23540. 题目: Mechanism analysis to improve sludge dewaterability during anaerobic digestion based on moisture distribution
文章编号: N19041303
期刊: Chemosphere
作者: Wei Zhang, Bin Dong, Xiaohu Dai
更新时间: 2019-04-13
摘要: Previous studies have demonstrated that anaerobic digestion (AD) enhances sludge dewaterability. However, the mechanism of AD influence on digested sludge dewaterability is still not well understood. In this study, moisture distribution and bond energy were used to evaluate the influence of AD on sludge dewaterability. The change from free moisture (FM) to mechanically bound moisture (MBM) was analysed, along with degradation of organic fractions in extracellular polymeric substances (EPSs) of the sludge during AD. Results indicated that the AD process, with a 41.9% reduction in volatile solids (VS) and cumulative methane production of 283.2 mL/g VS, improved sludge dewaterability by disintegrating macro-molecular organic matter into micro-molecular matter. MBM reduction reached 7% in 40 days. Correlations between FM/MBM and extracellular protein (extra-PN) were significant (R = −0.861, p < 0.01; R = 0.869, p < 0.01). Therefore, it can be concluded that the degradation of protein in the extra-microcolony polymer (EMPS) layer results in the destruction of the bond between organic fractions and moisture. As a result, the release of mechanically bound moisture is accelerated. In addition, the moisture content, as well as the extra-PN, continued to vary when AD entered the stabilisation stage, that is, the destruction of protein in EMPS stimulated mechanically bound moisture release during AD. The results of this work provide a better understanding on the effect of AD on sludge reduction.
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