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Biodegradation and Identification of Transformation Products of Fluorene by Ascomycete Fungi Texte intégral
2015
Kristanti, Risky Ayu | Hadibarata, Tony
Fluorene belongs to the polycyclic aromatic hydrocarbons (PAHs) which are potentially carcinogenic or mutagenic. However, very few studies on biodegradation of three-ring fluorene were investigated as compared to other three-ring PAHs such as phenanthrene and anthracene. The aim of this work is to evaluate fluorene degradation by fungal strain isolated from the decayed wood in tropical rain forest, Malaysia, and examine the effectiveness of the strain for degrading fluorene in liquid culture supplemented with the nonionic surfactants. Detailed taxonomic studies identified the organisms as Pestalotiopsis species and designated as strain Pestalotiopsis sp. W15. In this study, fluorene was totally degraded by Pestalotiopsis sp. W15 after incubation for 23 days. Various analytical studies confirmed the biotransformation of fluorene by detection of two metabolites in the treated medium: indanone (R f 0.45; λ ₘₐₓ 240 and 290 nm; t R 7.1 min and m/z 132) and salicylic acid (λ ₘₐₓ 205, 235, 290 nm; t R 9.4 min and m/z 382). Based on these products, a probable pathway has been proposed for the degradation of fluorene by Pestalotiopsis sp. W15. None of the intermediates were identified as dead-end metabolites.
Afficher plus [+] Moins [-]Diversity and Spatial Structure of Soil Fungi and Arbuscular Mycorrhizal Fungi in Forest Litter Contaminated with Copper Smelter Emissions Texte intégral
2015
Mikryukov, V. S. | Dulya, O. V. | Vorobeichik, E. L.
The diversity and spatial structure of soil fungi (SF) and arbuscular mycorrhizal fungi (AMF) communities in the southern taiga forest litter were studied in sites with two contrasting contamination levels with copper smelter emissions. The operational taxonomic unit richness and evenness in the communities of both target groups decreased under contamination. The community structure of contaminated and control areas differed for SF, whereas they were similar for AMF. According to spatial structure analysis results on a scale of tens of meters, a gradual change of composition with distance was revealed for the SF community within 30-m intervals in the control sites. No spatial autocorrelation was found for AMF in the control sites. However, pronounced patchiness was characteristic of both SF and AMF communities within 10 m of contaminated sites. In the contaminated area, no specific spatial structure determinants of the studied communities was found among environmental factors such as water content, heavy metal concentrations in the forest litter, sample plot localization relative to canopy density, and herb vegetation diversity and abundance. However, in the control sites, AMF richness depended on herb abundance and litter chemistry.
Afficher plus [+] Moins [-]Accumulation of Traffic-Related Trace Metals in Urban Winter-Long Roadside Snowbanks Texte intégral
2015
Moghadas, S. | Paus, K. H. | Muthanna, T. M. | Herrmann, I. | Marsalek, J. | Viklander, M.
Accumulations of mass loads of selected chemicals in roadside snowbanks were studied at five sites with various traffic densities in the city of Trondheim (Norway) by collecting snow samples throughout the winter period and analyzing them for 13 water quality constituents: pH, electrical conductivity (EC), alkalinity, Cl, Na, total suspended solids (TSS), Cd, Cr, Cu. Ni, Pb, W, and Zn. The resulting dataset was then supplemented by similar data collected earlier in the city of Luleå (Sweden). Regression analyses for individual sites indicated linear trends in unit-area constituent accumulations with time (0.65 < R ² < 0.95) and supported the assumption of linearity in further analyses. Principal component analysis (PCA) of the combined Luleå/Trondheim data revealed cause-effect relationships between the chemical mass loadings (TSS and trace metals) and three predictors: snow age (snow residence time (SRT)), traffic density (annual average density of traffic (AADT), and cumulative traffic volume (CTV = SRT × AADT). Cl and Na loads, originating from road salt applications in Trondheim only, did not display this trend. Two types of parsimonious models for predicting trace metal accumulations in winter-long roadside snowbanks were developed: (a) a linear regression model using CTV as a single predictor and predicting metal accumulations with a moderate certainty (0.37 < R ² < 0.66) and (b) multiple regression models using SRT, AADT, and snow water equivalent (SWE) as predictors. The latter models indicated good correlations between the mass loads and the predictors (0.64 < R ² < 0.77) and produced slightly better prediction accuracies (0.44 < R ² < 0.67) than the simpler model.
Afficher plus [+] Moins [-]Vertical Greenery Systems as a Strategy in Urban Heat Island Mitigation Texte intégral
2015
Price, Alexandra | Jones, Erick C. | Jefferson, Felicia
Integrating vegetation into architecture has become widely recognized as a multi-beneficial practice in architecture and engineering design to combat an array of environmental issues. Urban areas have microclimates that are different than the climates of their surrounding rural areas. Patterns in these differences over the years have shown that urban microclimates tend to be significantly warmer in comparison. This phenomenon is now recognized as the urban “heat island” effect. While the associated consequences of this urban heating are far reaching, excess energy expenditure, air pollution emissions, and threats to human health are among the most critical for evaluation. The integration of vegetative green space in urban planning, coupled with highly reflective materials in place of conventional paved surfaces on roads and rooftops have proven to be effective methods of urban heat island mitigation. While as separate entities these methods are effective, innovative technology has brought forth greening roofs which allows vegetation to compensate where other roof-cooling strategies fall short. Substantially, vertical greenery systems compensate where greening roofs fall short. This paper explores both integrated vegetation as an optimal mitigation strategy for urban heat islands and vertical plant walls as an optimal design.
Afficher plus [+] Moins [-]Arsenic Adsorption and its Fractions on Aquifer Sediment: Effect of pH, Arsenic Species, and Iron/Manganese Minerals Texte intégral
2015
Ma, Jie | Guo, Huaming | Lei, Mei | Zhou, Xiaoyong | Li, Fulan | Yu, Tian | Wei, Rongfei | Zhang, Hanzhi | Zhang, Xi | Wu, Yang
Effects of pH, As species, and Fe/Mn minerals on the fractions of adsorbed As in aquifer sediments were evaluated. Kinetic data showed that As adsorption was controlled by diffusion through the external film. Isothermal data of both As(III) and As(V) fitted the Langmuir isotherm well, revealing a monolayer adsorption process. Sequential extraction demonstrated that water-soluble As and non-specifically sorbed As were the major fractions of adsorbed As. Assessing the relationship between the Freundlich K F and the increases in the amounts of As fractions showed that the pH played a key role in weakly adsorbed As, especially water-soluble As. Although inorganic As species converted each other during the adsorption processes, more non-specifically sorbed As was adsorbed in As(V)-treated sediment than in As(III)-treated sediment, showing that the electrostatic selectivity controlled the non-specific adsorption. Additionally, specifically sorbed As and As associated with the amorphous phases were predominated by Fe/Mn minerals, especially Fe(III) (hydr)oxides. These results suggested that pH, As species, and Fe/Mn minerals would regulate the As fractions in aquifer sediments, and therefore control As cycling in aquifer systems.
Afficher plus [+] Moins [-]Nano Photo Catalytic Degradation of the Pharmaceutical Agent Balsalazide Under UV Slurry Photo Reactor Texte intégral
2015
Sikarwar, Shalini | Jain, Rajeev
The presence of pharmaceuticals and personal care products (PPCPs) as trace pollutants in natural surface water bodies, ground water and drinking water has recently led to some concern. Advanced oxidation processes (AOPs), which utilize free radical reactions to degrade chemical contaminates, are an alternative to traditional water treatment. Anti-inflammatory drug balsalazide (as model compounds) besides actual wastewater samples were UV photodegraded using suspended titanium silicon oxide (TiSiO₄) or UV/H₂O₂/O₂ systems. The photodegradation was favourable in the pH 8–12.8 range. The effect of various parameters such as photocatalyst amount, balsalazide (BSZ) concentration, pH of aqueous solution, irradiation time, addition of H₂O₂ and temperature on photocatalytic oxidation was investigated. The kinetics of the photocatalytic oxidation of BSZ in aqueous TiSiO₄ suspensions was investigated as a function of catalyst loading (2–12 mg/L) and the concentration of BSZ (0.01–0.05 mg/mL) at pH 11.5. The optimum conditions for the degradation of the BSZ have been found as 0.045 mg/mL drug concentration, pH 11.5 and 0.1 g/L catalyst dose. The results indicated that the photocatalytic degradation of BSZ was well described by pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. The effect of temperature on the efficiency of photodegradation of BSZ was also studied in the range 278–298 K. The activation energy was calculated according to Arrhenius plot and was found equal to 24 ± 1 kJ mol⁻¹ for TiSiO₄. Decolourization and mineralization of BSZ in the absence of light and/or catalyst were performed to demonstrate that the presence of light and catalyst is essential for the decolourization of this BSZ. This work adds to the global discussion on the role of the advanced oxidation processes in water treatment.
Afficher plus [+] Moins [-]Benzotriazoles in the Aquatic Environment: a Review of Their Occurrence, Toxicity, Degradation and Analysis Texte intégral
2015
Alotaibi, M. D. | McKinley, A. J. | Patterson, B. M. | Reeder, A. Y.
Benzotriazoles (BTs) are an emerging class of environmental pollutants used in a wide range of industrial applications. Benzotriazole (BTri) and 5-methylbenzotriazole (5-MeBT) have recently been detected in water supplies around the world, and are thus attracting the attention of many environmental researchers. The focus of this review is on assessing contemporary methods to detect BTs using high-performance liquid chromatography (HPLC), and providing information regarding their occurrence, degradation and toxicity within the environment.
Afficher plus [+] Moins [-]Effects of Roadside Deposition on Growth and Pollutant Accumulation by Willow (Salix miyabeana) Texte intégral
2015
Heintzman, Rebecca L. | Titus, John E. | Zhu, Weixing
Roadside plants have the potential to accumulate pollutants and safeguard waterways. To assess growth and pollutant accumulation of roadside plants, the willow Salix miyabeana was grown (a) in a greenhouse on soil collected at different distances from an interstate highway to test the longer-term effects of pollutant deposition as manifested in soil, and (b) in the field on reference soil placed at different distances from that highway to test the shorter-term effects of proximity to pollutant sources during a single growing season. In the first experiment, relative growth rate (RGR) increased 150 % with distance of soil collection from the roadway, from a baseline near the highway to 100 m away. Relative nitrogen and phosphorus accumulation rates were positively correlated with RGR (P <0.0001), and total contents of zinc, strontium, copper, nickel, cadmium, and lead in new shoots were also positively correlated with RGR (P <0.05). Thus more rapidly growing plants accumulated more N, P, and metals. Reduced growth for plants grown on soils collected near the roadway was associated with very high tissue concentrations of sodium and soil concentrations of chloride, implicating the deposition of deicing agents in this northern temperate roadside ecosystem. In contrast, S. miyabeana showed the opposite pattern on reference soil in the field, with RGR decreasing 31 % as distance from the roadside increased. The latter trend appears to have resulted from greater soil moisture and reduced shading near the highway. We suggest that reducing road salt applications will promote growth and pollutant accumulation by roadside vegetation.
Afficher plus [+] Moins [-]The Removal of Antimony by Novel NZVI-Zeolite: the Role of Iron Transformation Texte intégral
2015
Zhou, Zhe | Dai, Chaomeng | Zhou, Xuefei | Zhao, Jianfu | Zhang, Yalei
Nanoscale zero valent iron (NZVI) supported on beta zeolite was synthesized by refined method for the removal of Sb(III) and characterized with TEM-EDX, XRD, XPS, BET, and Zetasizer. The results showed that NZVI existed as apparent ones doping on surface of beta zeolite (average size 20–40 nm) and fine ones formed in structure of beta zeolite (<1 nm). Compared to NZVI, NZVI-zeolite showed enhanced antimony removal ability and higher iron efficiency due to its better dispersibility and smaller size. Adsorption and reduction ability of iron played main roles in the antimony removal. The removal isotherm was better fitted by Freundlich model. According to XPS analysis, reduction of Sb(III) happened rapidly and Sb(0) took more than 80 % in final products, which was higher compared with NZI. Iron transformation accompanied with antimony removal was identified by XRD and XPS, which caused antimony reduction and facilitate further immobilization of removed antimony. The iron oxides encapsulated antimony in their own structure and beta zeolite which they adhere. The theoretical model about the process was proposed to illustrate NZVI-zeolite enhanced antimony removal ability.
Afficher plus [+] Moins [-]Effects of Polychlorinated Dibenzo-p-dioxins on Soil Nutrition, Soil CO2 Emission, and Mung Bean Seedling Growth Texte intégral
2015
Liu, Qiang | Chen, Yiping | Sun, Benhua
Dioxins are a group of persistent organic pollutants with varying degrees of toxicity. To determine the effects of polychlorinated dibenzo-p-dioxins pollution on soil nutrition, soil carbon dioxide (CO₂) emission, and plant growth, soils and mung bean seedlings were experimentally subjected to 1,2,3,7,8-pentachlorodibenzo-para-dioxin (PeCDD). The results showed that: (i) Low dose of PeCDD treatments led to a significant decrease in the soil organic matter content and an increase in the hydrolyzable nitrogen content, while the contents of available phosphorus and exchangeable potassium decreased significantly at high doses of PeCDD (≥20 ng kg⁻¹). (ii) The soil CO₂release rate was gradually increased from treatments with 10 to 20 ng kg⁻¹PeCDD, but decreased significantly with 30 ng kg⁻¹PeCDD treatment after 25 days exposure. With prolonged exposure time, the soil CO₂emission after all treatments declined heavily, along with the difference among different treatments. (iii) Low dose of 10 ng kg⁻¹PeCDD resulted in significant reductions of malondialdehyde (MDA) content and electrolyte leakage conductivity and increases in the contents of chlorophyll and soluble protein and fresh biomass of mung bean seedlings. On the contrary, high doses of PeCDD (≥20 ng kg⁻¹) treatments showed opposite effects on the above parameters of seedling growth. The results suggested that high doses of PeCDD contamination (≥20 ng kg⁻¹) posed potential negative effects on the cycling processes of soil nutrients, which were probably due to the inhibitory on soil microbial activity, and induced phytotoxicity on seedling growth, although slight stimulations of soil microbial activity and mung bean seedling growth were found at low doses of PeCDD. Therefore, more efforts are needed to ensure the dioxin contamination below the toxic concentration of 20 ng TEQ kg⁻¹in farmland soil.
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