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30581. 题目: Management versus site effects on the abundance of nitrifiers and denitrifiers in European mountain grasslands
文章编号: N18081901
期刊: Science of The Total Environment
作者: Ute Szukics, Karl Grigulis, Nicolas Legay, Eva-Maria Kastl, Catherine Baxendale, Richard D. Bardgett, Jean-Christophe Clément, Sandra Lavorel, Michael Schloter, Michael Bahn
更新时间: 2018-08-19
摘要: It is well established that the abundances of nitrogen (N) transforming microbes are strongly influenced by land-use intensity in lowland grasslands. However, their responses to management change in less productive and less fertilized mountain grasslands are largely unknown. We studied eight mountain grasslands, positioned along gradients of management intensity in Austria, the UK, and France, which differed in their historical management trajectories. We measured the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) as well as nitrite-reducing bacteria using specific marker genes. We found that management affected the abundance of these microbial groups along each transect, though the specific responses differed between sites, due to different management histories and resulting variations in environmental parameters. In Austria, cessation of management caused an increase in nirK and nirS gene abundances. In the UK, intensification of grassland management led to 10-fold increases in the abundances of AOA and AOB and doubling of nirK gene abundance. In France, ploughing of previously mown grassland caused a 20-fold increase in AOA abundance. Across sites the abundance of AOB was most strongly related to soil NO₃⁻-N availability, and AOA were favored by higher soil pH. Among the nitrite reducers, nirS abundance correlated most strongly with N parameters, such as soil NO₃⁻-N, microbial N, leachate NH₄⁺-N, while the abundance of nirK-denitrifiers was affected by soil total N, organic matter (SOM) and water content. We conclude that alteration of soil environmental conditions is the dominant mechanism by which land management practices influence the abundance of each group of ammonia oxidizers and nitrite reducers.
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30582. 题目: Comparison of different detoxification pilot plants for the treatment of industrial wastewater by solar photo-Fenton: Are raceway pond reactors a feasible option?
文章编号: N18081810
期刊: Science of The Total Environment
作者: A. Cabrera-Reina, S. Miralles-Cuevas, G. Rivas, J.A. Sánchez Pérez
更新时间: 2018-08-18
摘要: This paper represents a first approach in the study of photoreactor selection to treat industrial wastewater using solar photo-Fenton. In this context, simulated textile industry effluent containing a mixture of four dyes at different initial dissolved organic carbon (DOC) concentrations (45, 90, 180 and 270 mg/L) was treated by using three different solar reactor geometries: (i) tubular (5 cm diameter) provided with compound parabolic collector (ii) tubular (5 cm diameter) provided with flat collector and (iii) open channels forming raceway ponds with two liquid depths (5 and 15 cm). For comparison purposes, mineralisation percentages over 75% and chronic toxicity reduction were set as treatment goals. Regardless of the initial DOC concentration, negligible differences in terms of treatment time and hydrogen peroxide consumptions were found between the flat collector and compound parabolic collector photoreactors. Conversely, the treatment in the raceway pond reactors always resulted in higher values. In spite of this, when the photoreactors were compared in terms of treatment capacity (mg of DOC removed/m² min) the raceway pond reactor at 15 cm of liquid depth presented the best results, with values as much as two or three times higher than those of the tubular reactors, except for the wastewater with 270 mg of DOC/L for which the raceway pond reactor at 5 cm liquid depth became the best option. When the treatment capacity is modified to include the photoreactor investment (mg of DOC removed/€ m²) the differences between the raceway pond reactor at both liquid depths and the photoreactors with solar collectors increased by as much as two orders of magnitude, which demonstrates the potential application of the former for the treatment of industrial wastewater by solar photo-Fenton.
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30583. 题目: Effects of sediment components and TiO 2 nanoparticles on perfluorooctane sulfonate adsorption properties
文章编号: N18081809
期刊: Journal of Soils and Sediments
作者: Kun Li, Peifang Wang, Jin Qian, Chao Wang, Linghang Xing, Jingjing Liu, Xin Tian, Bianhe Lu, Wenyi Tang
更新时间: 2018-08-18
摘要: Purpose: Here, the roles of sediment components in perfluorooctane sulfonate (PFOS) adsorption onto aquatic sediments and relevant adsorption mechanisms were investigated in terms of adsorption isotherms and influences of TiO₂ nanoparticles (NPs) contamination. Materials and methods: Due to the complexity of the sediments, instead of randomly selecting different component sediments, the selective dissolution method was used to better explore the effects of sediment compositions, such as sediment organic matter (SOM) and ferric oxides (dithionite–citrate–bicarbonate [DCB] Fe), and TiO₂ NPs pollution on PFOS adsorption. Mathematical equations (Freundlich, Langmuir, and Temkin) were used to describe the adsorption behavior of PFOS on different sediments and adsorption mechanisms of multiple pollutant interactions. Moreover, the characterization methods of zeta potential, nitrogen (N₂) adsorption–desorption, and scanning electron microscopy (SEM) analysis, as well as Fourier transform infrared (FT-IR) spectroscopy, explained effects of the sediment components and TiO₂ NPs on PFOS adsorption properties in view of physicochemical theories. Results and discussion: The adsorption isotherms of PFOS on six tested sediments were all nonlinear (Freundlich model, R² = 0.992~1.000). The Freundlich sorption affinities (K_F) of PFOS on S (original sediments), S1 (sediment organic matter (SOM)-removed S), and S2 (ferric oxides (DCB Fe)-removed S1) were 0.232, 0.179, and 0.120, respectively. Both SOM and DCB Fe influenced the physicochemical properties of the sediments, e.g., zeta potential, specific surface area, and permanent negative charge. The addition of TiO₂ NPs increased the K_F of PFOS for S, S1, and S2 by approximately 9.9%, 14.5%, and 26.7%, respectively, by increasing the zeta potential and specific surface area (S_BET, S_ext, and S_micro) and by changing the water and oil properties of the three sediments. However, the addition of TiO₂ NPs decreased the linearity of the sorption isotherm (1/n). FT-IR spectroscopy showed that hydrophobicity, ion exchange, surface complexation, and hydrogen bonding interactions (non-fingerprint region) could all play a role in PFOS sorption onto tested sediments. However, the hypothesis of hydrogen bonding to promote PFOS adsorption on sediment layer silicates (fingerprint region) should be studied further. Conclusions: The content of both SOM and DCB Fe affected the physicochemical properties of sediment. Both SOM and DCB Fe showed a positive relationship with sorption of PFOS on sediment. The addition of TiO₂ NPs increased PFOS sorption by altering the sediment surface properties. Hydrophobic interactions certainly impelled and ligand and ion exchange and hydrogen bonding (non-fingerprint region) could promote PFOS sorption on the sediments.

30584. 题目: Chronic toxicity of an environmentally relevant and equitoxic ratio of five metals to two Antarctic marine microalgae shows complex mixture interactivity
文章编号: N18081808
期刊: Environmental Pollution
作者: Darren J. Koppel, Merrin S. Adams, Catherine K. King, Dianne F. Jolley
更新时间: 2018-08-18
摘要: Metal contaminants are rarely present in the environment individually, yet environmental quality guidelines are derived from single-metal toxicity data. Few metal mixture studies have investigated more than binary mixtures and many are at unrealistically high effect concentrations to freshwater organisms. This study investigates the toxicity of five metals (Cd, Cu, Ni, Pb, and Zn) to the Antarctic marine microalgae Phaeocystis antarctica and Cryothecomonas armigera. Two mixtures were tested: (i) an equitoxic mixture of contaminants present at their single-metal EC10 concentrations, and (ii) an environmental mixture based on the ratio metal concentrations in a contaminated Antarctic marine bay.Observed toxicity, as chronic population growth rate inhibition, was compared to Independent Action (IA) and Concentration Addition (CA) predictions parameterised to use EC10 values. This allowed for the inclusion of metals with low toxicities. The biomarkers chlorophyll a fluorescence, cell size and complexity, and intracellular lipid concentrations were assessed to investigate possible mechanisms behind metal-mixture interactions.Both microalgae had similar responses to the equitoxic mixture: non-interactive by IA and antagonistic by CA. Toxicity from the environmental mixture was antagonistic by IA to P. antarctica; however, to C. armigera it was concentration-dependent with antagonism at low toxicities and synergism at high toxicities by both IA and CA. Differences in dissolved organic carbon production and detoxification mechanisms may be responsible for these responses and warrants further investigation.This study shows that mixture toxicity interactions can be ratio, species, and concentration dependent. The responses of the microalgae to different mixture ratios highlight the need to assess toxicity at environmentally realistic metal ratios. Parameterising IA and CA reference models to use EC10s allowed for the inclusion of metals at low effect concentrations, which may otherwise be ignored. Reference mixture models are generally suitable for predicting chronic toxicity of metals to these marine microalgae at environmentally realistic ratios and concentrations.
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30585. 题目: Volatile fatty acids production from food wastes for biorefinery platforms: A review
文章编号: N18081807
期刊: Journal of Environmental Management
作者: Giuseppe Strazzera, Federico Battista, Natalia Herrero Garcia, Nicola Frison, David Bolzonella
更新时间: 2018-08-18
摘要: Volatile fatty acids (VFAs) are a class of largely used compounds in the chemical industry, serving as starting molecules for bioenergy production and for the synthesis of a variety of products, such as biopolymers, reduced chemicals and derivatives. Because of the huge amounts of food waste generated from household and processing industry, 47 and 17 million tons per year respectively only in the EU-28 Countries, food wastes can be the right candidate for volatile fatty acids production. This review investigates all the major topics involved in the optimization of VFAs production from food wastes. Regarding the best operative conditions for the anaerobic fermenter controlled pH in the neutral range (6.0–7.0), short HRT (lower than 10 days), thermophilic temperatures and an organic loading rate of about 10 kgVS/m³d, allowed for an increase in the VFAs concentration between 10 and 25%. It was also found that additions of mineral acids, from 0.5 to 3.0%, and thermal pretreatment in the range 140–170 °C increase the organic matter solubilisation. Applications of VFAs considered in this study were biofuels and bioplastics production as well as nutrients removal in biological wastewater treatment processes.
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30586. 题目: Clay amount and distribution influence organic carbon content in sand with subsoil clay addition
文章编号: N18081806
期刊: Soil and Tillage Research
作者: Amanda Schapel, Petra Marschner, Jock Churchman
更新时间: 2018-08-18
摘要: Sandy soils cover large proportions of Australia’s cereal-cropping region and are wide-spread globally. Sandy soils often have low organic C (OC) content due to limited plant growth and rapid decomposition because of low clay concentration. The addition of subsoil clay to sandy soil has the potential to increase OC storage. This study aimed to (i) compare OC stock in a range of clay-amended and unamended sandy soils under cereal cropping and (ii) identify factors that influence OC stock to develop best practices to increase OC storage in clay-amended sandy soils. The study was carried out on four agricultural properties in South Australia and assessed soil OC content, clay content and select physical and chemical properties of clay-amended treatments compared to unamended sands. Clay-amendment treatments differed in the method of clay amendment (clay spread and delved), depth of incorporation (shallow and deep) and amount of subsoil clay added to the surface 30 cm of sand. For each site and treatment, ten soil cores to 50 cm depth were collected within a 25 m grid. There was a positive correlation between OC and clay stock, but it only explained 46% of the variation in OC stock. This indicated that other factors influenced OC stock in clay-amended treatments. Even vertical distribution of clay within the surface 30 cm was a key factor to increase OC storage in clay-amended soils. Subsoil clay properties and the amount added to the surface 30 cm, as well as depth to undisturbed subsoil also influenced OC stock.

30587. 题目: Fabrication of GO/CDots/BiOI nanocomposites with enhanced photocatalytic 4-chlorophenol degradation and mechanism insight
文章编号: N18081805
期刊: Separation and Purification Technology
作者: Songying Qu, Yuhan Xiong, Jun Zhang
更新时间: 2018-08-18
摘要: Non-metallic graphene oxide (GO) and carbon nanodots (CDots) co-doped BiOI ternary system (GO/CDots/BiOI) was successfully synthesized via a simple one-step solvothermal process. The compositional characterization, optical and electrical properties of photocatalysts were investigated in detail. The prepared ternary photocatalysts possessed the excellent visible-light driven photocatalytic 4-chlorophenol (4-CP) degradation. Additionally, the 4-CP removal efficiencies decreased in the order of GO/CDots/BiOI (98.2%) > CDots/BiOI (89.9%) > GO/BiOI (78.5%) > pristine BiOI (41.7%) in 3 h under visible light irradiation. The dissolved organic carbon (DOC) removal and the dechlorination efficiency by the GO/CDots/BiOI were 66.3% and 85.2%, respectively, much higher than pristine BiOI. The co-existence of GO and CDots on the BiOI greatly promoted visible light harvesting and utilizing ability and inhibited the recombination of photogenerated electron/hole pairs. The synergistic effect between GO, CDots and BiOI was expounded, and the photocatalytic reaction mechanism was proposed in detail via the band structure analysis and free radical trapping experiments.
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30588. 题目: Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte‐dominated systems with zero net effect on carbon burial
文章编号: N18081804
期刊: Global Change Biology
作者: Mandy Velthuis, Sarian Kosten, Ralf Aben, Garabet Kazanjian, Sabine Hilt, Edwin T. H. M. Peeters, Ellen van Donk, Elisabeth S. Bakker
更新时间: 2018-08-18
摘要: Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year‐round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year‐round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m⁻² yaer⁻¹ (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m⁻² year⁻¹ in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte‐dominated systems, while not necessarily affecting net carbon burial on a system scale.

30589. 题目: The prediction of mercury bioavailability for common carp (Cyprinus carpio L.) using the DGT technique in the presence of chloride ions and humic acid
文章编号: N18081803
期刊: Chemosphere
作者: Pavlína Pelcová, Petra Vičarová, Hana Dočekalová, Eva Poštulková, Radovan Kopp, Jan Mareš, Vendula Smolíková
更新时间: 2018-08-18
摘要: The ability of the DGT technique to predict Hg²⁺ bioavailability for input tissues (skin, gills, and scales) of common carp in the presence of chloride ions and humic acid (HA) was evaluated. The mercury accumulation by the DGT units and input tissues of carp decreased with an increasing concentration of chloride ions (29–180 mg L⁻¹) and HA (0–5 mg L⁻¹). In the presence of chloride ions and HA, statistically significant correlations (Pearson's correlation coefficients 0.731–0.954) were determined between the rate of mercury accumulation by input tissues of carp and the rate of mercury accumulation by the DGT units. The laboratory experiments suggest the possibility of using the DGT technique for predicting the mercury bioaccumulation in natural aquatic ecosystems instead of commonly used input tissues of fish.
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30590. 题目: Relationship between home-field advantage of litter decomposition and priming of soil organic matter
文章编号: N18081802
期刊: Soil Biology and Biochemistry
作者: D.P. Di Lonardo, M. Manrubia, W. De Boer, H. Zweers, G.F. Veen, A. Van der Wal
更新时间: 2018-08-18
摘要: Home field advantage (HFA; acceleration of plant litter decomposition in soils that receive their indigenous litter) and priming effects (PE; short-term changes in the turnover of soil organic matter caused by the addition of fresh organic carbon) are two aspects of decomposition processes that are driven by the composition and functioning of soil decomposer communities. Physicochemical similarity between added organic compounds and soil organic matter fractions has been indicated as an important steering factor of PE. It is unknown whether PE, like litter decomposition, experience HFA, i.e., whether PE are higher than expected in soils receiving their own litter due to specialization of the decomposer community. Here we studied both HFA and PE by measuring litter- and SOM-derived carbon (C) fluxes after the addition of fresh plant litter. We reciprocally incubated three ¹³C labelled litter types (maize, bent and beech) in soils from ecosystems where these litters are abundantly produced (e.g., arable sites, grasslands and forests), with and without the addition of mineral nitrogen (N). Generally, respiration of both litter-derived and SOM-derived C were lowest when beech litter was added, and were lower in forest soils than in arable or grassland soils. N addition generally slightly increased the respiration of litter-derived C, but had no effect on SOM-derived C. All litter types induced a positive PE in all soils. HFA effects were not significantly different from zero, but were significantly higher in grasslands than in maize fields amended with nitrogen. We found a positive relationship between litter and priming HFA, indicating that the rates of both litter decomposition and PE may be affected in the same manner by home combinations of plant and litter versus away combinations. This positive relationship disappeared when N was added. Our results provide a first indication that the extent to which indigenous soil microbes are specialized to breakdown home litter, not only accelerates or decelerates the decomposition of litter, but affects the breakdown of SOM in the same way. This could imply that a specialized litter decomposer community driving HFA can further accelerate soil C mineralization via enhanced induction of PE. Therefore, the impact of specialized decomposer communities on the dynamics of soil C pools may be bigger than expected from HFA of litter decomposition alone.

30591. 题目: A review of landfill leachate induced ultraviolet quenching substances: Sources, characteristics, and treatment
文章编号: N18081801
期刊: Water Research
作者: Syeed Md Iskander, Renzun Zhao, Ankit Pathak, Abhinav Gupta, Amy Pruden, John T. Novak, Zhen He
更新时间: 2018-08-18
摘要: Landfill leachate contains extremely diverse mixtures of pollutants and thus requires appropriate treatment before discharge. Co-treatment of landfill leachate with sewage in wastewater treatment plants is a common approach because of low cost and convenience. However, some recalcitrant organic compounds in leachate can escape biological treatment processes, lower the UV transmittance of waste streams due to their UV-quenching properties, and interfere with the associated disinfection efficacy. Thus, the leachate UV quenching substances (UVQS) must be removed or reduced to a level that UV disinfection is not strongly affected. UVQS consist of three major fractions, humic acids, fulvic acids and hydrophilics, each of which has distinct characteristics and behaviors during treatment. The purpose of this review is to provide a synthesis of the state of the science regarding UVQS and possible treatment approaches. In general, chemical, electrochemical, and physical treatments are more effective than biological treatments, but also costlier. Integration of multiple treatment methods to target the removal of different fractions of UVQS can aid in optimizing treatment. The importance of UVQS effects on wastewater treatment should be better recognized and understood with implemented regulations and improved research and treatment practice.
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30592. 题目: Contrasting fates of petrogenic and biospheric carbon in the South China Sea
文章编号: N18081708
期刊: Geophysical Research Letters
作者: T. M. Blattmann, Y. Zhang, Y. Zhao, K. Wen, S. Lin, J. Li, L. Wacker, N. Haghipour, M. Plötze, Z. Liu, T. I. Eglinton
更新时间: 2018-08-17
摘要: A synthesis of published and newly acquired stable and radiocarbon isotope data fromsoil, river, and marine particulate organic carbon (OC) from the South China Sea drainageand sedimentary basin reveals that OC derived from bedrock‐erosion (petrogenic OC)and marine productivity comprise the major contributors to bulk OC in particulatematter reaching abyssal depths, while soil‐derived OC appears negligible. Aluminum‐radiocarbonrelationships of sediments suggest that soil OC initially associated with detritalterrestrial minerals is lost and replaced by marine OC during transport beyond thecontinental shelf. We estimate that petrogenic OC sinking to a ~30,000 km² region of the deep northeastern South China Sea accounts for 0.6% of global petrogenic OC burial. The basin‐wide OC isotope patterns coupled with sediment trap observationshighlight both the spatial variability of OC components as they propagate from sourceto sedimentary sink, and the significance of petrogenic OC to deep ocean sediments.

30593. 题目: Application and mechanism of nucleation-induced pelleting coagulation (NPC) in treatment of fracturing wastewater with high concentration of dissolved organic matter
文章编号: N18081707
期刊: Chemosphere
作者: Xin Jin, Weijie Zhang, Zhonglun Ji, Lihui Zhou, Pengkang Jin, Xiaochang C. Wang, Yaoyao Zhang
更新时间: 2018-08-17
摘要: To improve the separation efficiency of fluffy flocs during coagulation of fracturing wastewater with high concentration of dissolved organic matter, a novel nucleation-induced pelleting coagulation (NPC) process is proposed based on pelleting coagulation in this study. In the NPC process, nucleation agents were added to act as pellet seeds to generate high-density pellet flocs. The results implied that the necessary condition for the NPC process was to control the metastable state, i.e. zeta potential around −10 mV after addition of the coagulant, polyaluminium chloride (PAC). Diatomite, which was added after rapid mixing, was used as the nucleation agent, and its optimal dosage was about 100 mg/L with particle size 100–200 μm. In addition, the dosage of the coagulant aid, polyacrylamide (PAM), significantly affected the performance of the NPC process, and the optimal PAM dosage was 10 mg/L in this study. It was found that 60 rpm (G = 55.1 s⁻¹) was the optimal hydraulic condition for pellet growth during slow mixing. The pellet floc settling velocity reached 14.9 mm/s and the particle size (d₅₀) reached 4.6 mm with an effective density of 0.021 g/cm³ at the optimal condition, which was one order higher than that of conventional aluminium flocs.
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30594. 题目: Sediment characteristics influence the fertilisation success of the corals Acropora tenuis and Acropora millepora
文章编号: N18081706
期刊: Marine Pollution Bulletin
作者: Gerard F. Ricardo, Ross J. Jones, Peta L. Clode, Adriana Humanes, Natalie Giofre, Andrew P. Negri
更新时间: 2018-08-17
摘要: Elevated suspended sediment concentrations (SSCs) often impact coral fertilisation success, but sediment composition can influence effect thresholds, which is problematic for accurately predicting risk. Here, we derived concentration–response thresholds and cause-effect pathways for SSCs comprising a range of realistic mineral and organic compositions on coral fertilisation success. Effect concentration thresholds (EC₁₀: 10% fertilisation inhibition) varied markedly, with fertilisation highly sensitive to inshore organic-clay rich sediments and bentonite clay at <5 mg L⁻¹. Mineral clays and organic matter within these sediments likely promoted flocculation of the coral sperm, which in turn reduced fertilisation. In contrast, sediments lacking these properties bound less sperm, leading to higher SSC thresholds for coral fertilisation (EC₁₀ > 40 mg L⁻¹). The effect thresholds for relevant sediment types were combined with in situ turbidity data from locations near dredging operations to assess the risks posed by dredging to coral fertilisation at these locations.

30595. 题目: Enhanced cadmium immobilization in saturated media by gradual stabilization of goethite in the presence of humic acid with increasing pH
文章编号: N18081705
期刊: Science of The Total Environment
作者: Yali Chen, Jie Ma, Yongtao Li, Liping Weng
更新时间: 2018-08-17
摘要: Goethite (Gt) and humic acid (HA) are important components of soil that significantly affect Cd mobility. In this study, the co-transport of Cd²⁺ and Gt with/without HA in saturated sand columns was investigated by monitoring the breakthrough curves at different pH values. A solute transport model was used to study Cd²⁺ transport and retention in the saturated sand in the presence of Gt and HA, and a colloid transport model was used to describe the Gt colloid (Gt_C) transport in the columns. Our results showed that the transport behaviors of Cd²⁺ and Gt colloids/aggregates were regulated by pH. Cadmium transport was significantly inhibited at high pH due to its adsorption on the sand and Gt. Moreover, Gt retention was gradually stabilized with increasing pH regardless of its forms, i.e., individual colloids (Gt_C) or larger assemblages of particles due to aggregation (Gt_A). This retention was obviously enhanced in the presence of HA. Thus, the superposition of increased Cd²⁺ adsorption on Gt and Gt retention (stabilization) enhanced the immobilization of Cd²⁺ at high pH. In addition to stabilizing Gt, HA further enhance Cd²⁺ adsorption on Gt, thus promoting Cd²⁺ immobilization. However, only a small amount of organic-matter-bound Cd²⁺ was observed in the columns with injected HA. The major fractions of retained Cd²⁺ were exchangeable Cd²⁺ and Fe-oxide-bound Cd²⁺. Our results provide new insights into the roles of Gt and HA in the transport and mobilization of Cd²⁺ in soil-groundwater systems.
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30596. 题目: Efficient cephalexin degradation using active chlorine produced on ruthenium and iridium oxide anodes: Role of bath composition, analysis of degradation pathways and degradation extent
文章编号: N18081704
期刊: Science of The Total Environment
作者: Lic A. Perea, Ricardo E. Palma-Goyes, Jorge Vazquez-Arenas, Issis Romero-Ibarra, Carlos Ostos, Ricardo A. Torres-Palma
更新时间: 2018-08-17
摘要: The elimination of cephalexin (CPX) using electro-generated Cl₂-active on Ti/RuO₂-IrO₂ anode was assessed in different effluents: deionized water (DW), municipal wastewater (MWW) and urine. Single Ti/RuO₂ and Ti/IrO₂ catalysts were prepared to compare their morphologies and electrochemical behavior against the binary DSA. XRD and profile refinement suggest that Ti/RuO₂-IrO₂ forms a solid solution, where RuO₂ and IrO₂ growths are oriented by the TiO₂ substrate through substitution of Ir by Ru atoms within its rutile-type structure. SEM reveals mud-cracked structures with flat areas for all catalysts, while EDS analysis indicates atomic ratios in the range of the oxide stoichiometries in the nominal concentrations used during synthesis. A considerably higher CPX degradation is achieved in the presence of NaCl than in Na₂SO₄ or Na₃PO₄ media due to the active chlorine generation. A faster CPX degradation is reached when the current density is increased or the pH value is lowered. This last behavior may be ascribed to an acid-catalyzed reaction between HClO and CPX. Degradation rates of 22.5, 3.96, and 0.576 μmol L⁻¹ min⁻¹ were observed for DW, MWW and urine, respectively. The lower efficiency measured in these last two effluents was related to the presence of organic matter and urea in the matrix. A degradation pathway is proposed based on HPLC-DAD and HPLC-MS analysis, indicating the fast formation (5 min) of CPX-(S)-sulfoxide and CPX-(R)-sulfoxide, generated due the Cl₂-active attack at the CPX thioether. Furthermore, antimicrobial activity elimination of the treated solution is reached once CPX, and the initial by-products are considerably eliminated. Finally, even if only 16% of initial TOC is removed, BOD₅ tests prove the ability of electro-generated Cl₂-active to transform the antibiotic into biodegradable compounds. A similar strategy can be used for the abatement of other recalcitrant compounds contained in real water matrices such as urine and municipal wastewaters.
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30597. 题目: Comparative study of atmospheric water-soluble organic aerosols composition in contrasting suburban environments in the Iberian Peninsula Coast
文章编号: N18081703
期刊: Science of The Total Environment
作者: Regina M.B.O. Duarte, Maria Piñeiro-Iglesias, Purificación López-Mahía, Soledad Muniategui-Lorenzo, Jorge Moreda-Piñeiro, Artur M.S. Silva, Armando C. Duarte
更新时间: 2018-08-17
摘要: 'This study investigates the structural composition and major sources of water-soluble organic matter (WSOM) from PM_2.5 collected, in parallel, during summer and winter, in two contrasting suburban sites at Iberian Peninsula Coast: Aveiro (Portugal) and Coruña (Spain). PM₁₀ samples were also collected at Coruña for comparison. Ambient concentrations of PM_2.5, total nitrogen (TN), and WSOM were higher in Aveiro than in Coruña, with the highest levels found in winter at both locations. In Coruña, concentrations of PM₁₀, TN, and WSOM were higher than those from PM_2.5. Regardless of the season, stable isotopic δ¹³C and δ¹⁵N in PM_2.5 suggested important contributions of anthropogenic fresh organic aerosols (OAs) at Aveiro. In Coruña, δ¹³C and δ¹⁵N of PM_2.5 and PM₁₀ suggests decreased anthropogenic input during summer. Although excitation-emission fluorescence profiles were similar for all WSOM samples, multi-dimensional nuclear magnetic resonance (NMR) spectroscopy confirmed differences in their structural composition, reflecting differences in aging processes and/or local sources between the two locations. In PM_2.5 WSOM in Aveiro, the relative distribution of non-exchangeable proton functional groups was in the order: HC (40–43%) > HCC (31–39%) > HCO (12–15%) > Ar-H (5.0–13%). However, in PM_2.5 and PM₁₀ WSOM in Coruña, the relative contribution of HCO groups (24–30% and 23–29%, respectively) equals and/or surpasses that of HCC(25–26% and 25–29%, respectively), being also higher than those of Aveiro. In both locations, the highest aromatic contents were observed during winter due to biomass burning emissions. The structural composition of PM_2.5 and PM₁₀ WSOM in Coruña is dominated by oxygenated aliphatic compounds, reflecting the contribution of secondary OAs from biogenic, soil dust, and minor influence of anthropogenic emissions. In contrast, the composition of PM_2.5 WSOM in Aveiro appears to be significantly impacted by fresh and secondary anthropogenic OAs. Marine and biomass burning OAs are important contributors, common to both sites.'
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30598. 题目: Ballast water treatment and bacteria: Analysis of bacterial activity and diversity after treatment of simulated ballast water by electrochlorination and UV exposure
文章编号: N18081702
期刊: Science of The Total Environment
作者: Nanna B. Petersen, Torben Madsen, Mikkel A. Glaring, Fred C. Dobbs, Niels O.G. Jørgensen
更新时间: 2018-08-17
摘要: Effects of ballast water (BW) treatment by ultra-violet (UV) light and electrochlorination (EC) on survival, activity and diversity of marine bacterioplankton and release of organic matter from cell damage were examined at discharge in a large-scale BW test facility (250 m³ tanks) at Hundested harbour, Denmark. The tests were performed in accordance with the requirements for type approval testing by International Maritime Organization (IMO) and US Coast Guard. After treatment, the water was held in the tanks for one day (EC) before discharge, or 6 days (UV, including also a final UV re-treatment) before discharge. In the discharged and treated water, numbers of viable bacteria and bacterial growth rate had decreased significantly relative to the untreated water, but the total number of bacteria only was reduced in the EC-treated water. After additional storage for up to 10 days in small-scale laboratory incubations, significant regrowth of bacteria was observed after either treatment. Sequencing of 16S rRNA gene amplicons demonstrated that α-Proteobacteria initially were dominant, but γ-Proteobacteria dominated after regrowth. Bacteria used to document BW treatment efficiency (E. coli, Vibrio spp., enterococci) survived both treatments; neither treatment reduced the risk of pathogen dispersal. Concentrations of amino acids in the water were used as indicators of treatment-induced cell damage and demonstrated higher concentrations at discharge, but only after the EC treatments. Our results indicate that activity of bacteria, rather than their abundances, should be used when examining effects by ballast water treatment on microorganisms and that none of the examined treatment technologies could eliminate pathogenic bacteria.
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30599. 题目: Organic matter decomposition sustains sedimentary nitrogen loss in the Pearl River Estuary, China
文章编号: N18081701
期刊: Science of The Total Environment
作者: Ehui Tan, Wenbin Zou, Xinlei Jiang, Xianhui Wan, Ting-Chang Hsu, Zhenzhen Zheng, Ling Chen, Min Xu, Minhan Dai, Shuh-ji Kao
更新时间: 2018-08-17
摘要: The Pearl River Estuary (PRE) has long received tremendous amounts of anthropogenic nitrogen, and is facing severe environmental problems. Denitrification and anaerobic ammonium oxidation (anammox) are known to be two major nitrogen removal pathways in estuarine sediments. Through the use of slurry and intact sediment core incubations, we examined the nitrogen removal pathways and quantified the in situ denitrification and anammox with associated gaseous nitrogen production rates. Sedimentary nitrogen removal was predominated by denitrification (93–100%) relative to a minimal contribution (<7%) from anammox. Among the detected environmental factors, salinity, bottom water NO_x⁻ (nitrate and nitrite) concentration, sedimentary organic matter and dissolved oxygen consumption rates showed good correlations with denitrification and anammox rates. Sedimentary nitrogen loss was mainly supported by endogenic coupled nitrification-denitrification (6.0 ± 1.5 × 10⁶ mol N d⁻¹), with water-column-delivered NO_x⁻ (2.1 ± 0.6 × 10⁶ mol N d⁻¹) as the secondary source. Such results suggested that sedimentary nitrogen removal involved mainly particulate organic form (allochthonous or autochthonous) deposited onto sediments, rather than inorganic forms in overlying water. Meanwhile, total N₂O production from sediments was estimated to be 7.3 ± 2.1 × 10⁴ mol N d⁻¹, equivalent to ~35% of the daily N₂O emissions in the PRE.
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30600. 题目: Responses of soil bacterial communities, enzyme activities, and nutrients to agricultural-to-natural ecosystem conversion in the Loess Plateau, China
文章编号: N18081609
期刊: Journal of Soils and Sediments
作者: Yongxing Cui, Linchuan Fang, Xiaobin Guo, Xia Wang, Yunqiang Wang, Yanjiang Zhang, Xingchang Zhang
更新时间: 2018-08-16
摘要: Purpose: Soil microbial communities play critical function during nutrient cycling. However, with the increasing nutrient input into terrestrial ecosystems from human activities, the responses of soil microorganisms to the aboveground vegetation across agricultural-to-natural succession stages are still poorly understand. The aim of this study was to evaluate the changes of soil microbial communities in three typical succession stages (the cropland, the grassland, and the brushland, respectively). Materials and methods: A field experiment was carried out in an ecological restoration region. Soil samples were collected from three succession stages (the cropland, the grassland, and the brushland) based on their well-dated successional chronosequence in July 2016. Illumina MiSeq sequencing was used to identify the bacterial community structures. The responses of soil bacterial communities and its relationships with soil physicochemical properties and enzyme activities were assessed. Results and discussion: The results showed that soil nutrients (soil organic carbon (SOC), total N, and NH₄⁺) and enzyme activities (β-1,4-glucosidase and phosphatase) were significantly increased across the conversion from agricultural to natural ecosystem, and the enzyme activities were significantly affected by SOC and total N. It indicated that vegetation restoration greatly improved soil quality and nutrient cycling rates mediated by microbial metabolisms. Furthermore, there were no changes in soil bacterial community structures during the three vegetation succession stages, which implied the stability and adaption of microbial communities under the vegetation succession in semiarid climate. It should be noted that Firmicutes taxa were more sensitive than other taxa during natural vegetation recovery. Structural equation model (SEM) revealed that soil nutrients (soil organic matter (SOM) and total P), element stoichiometry (SOC:total P), and extracellular enzyme activities (urease and alkaline phosphatase) were dominant factors to shape the relative abundance of Firmicutes. Conclusions: Firmicutes can be considered as bio-indicators to monitor soil quality and nutrient turnover during natural vegetation recovery. This study presents better understanding about the connections among soil nutrient cycling, enzyme activities, and soil bacterial communities during vegetation natural restoration, especially in typical ecological critical zone.