خيارات البحث
النتائج 1191 - 1200 من 1,546
Identification of volatiles from Pinus silvestris attractive for Monochamus galloprovincialis using a SPME-GC/MS platform النص الكامل
2012
Szmigielski, Rafal | Cieslak, Marek | Rudzinski, Krzysztof J. | Maciejewska, Barbara
INTRODUCTION: A myriad of volatile organic compounds (VOCs) released by terrestrial vegetation plays an important role in environmental sciences. A thorough chemical identification of these species at the molecular level is essential in various fields, ranging from atmospheric chemistry to ecology of forest ecosystems. In particular, the recognition of VOCs profiles in a context of plant–insect communication is a key issue for the development of forest protection tools. PURPOSE: This work was aimed at the development of a simple, robust and reliable method for the identification of volatiles emitted from plant materials, which can attract or deter pest insects. Specifically, volatiles emitted from the bark of Pinus sylvestris were studied, which might attract the black pine sawyer beetle Monochamus galloprovincialis—a serious pest of the tree and a vector of a parasitic nematode Bursaphelenchus xylophius. METHOD: The volatiles from bark samples were collected using a solid-phase micro-extraction technique, and subsequently analysed by gas-chromatography/mass-spectrometry (GC/MS). The characterisation of the volatile fraction was based on the comparison with data in mass spectral libraries, and in most cases, with the available authentic standards. The identified compounds were screened against the available entomological data to select insect attractors. RESULTS: The identified components included terpenes (α-pinene, ∆-3-carene, and para-cymenene), oxygenated terpenes (α-terpineol and verbenone), sesquiterpenes (α-longipinene, longifolene, E-β-farnesene, γ-cadinene and pentadecane), and diterpenes (manoyl oxide and (+)-pimaral). Of these, longifolene and (+)-pimaral are of particular interest as plausible attractors for the M. galloprovincialis beetle that might find application in the construction of insect bait traps.
اظهر المزيد [+] اقل [-]Urban transformation of a metropolis and its environmental impacts : A case study in Shanghai النص الكامل
2012
Tian, Zhan | Cao, Guiying | Shi, Jun | McCallum, Ian | Cui, Linli | Fan, Dongli | Li, Xinhu
PURPOSE: The aim of this paper is to understand the sustainability of urban spatial transformation in the process of rapid urbanization, and calls for future research on the demographic and economic dimensions of climate change. Shanghai towards its transformation to a metropolis has experienced vast socioeconomic and ecological change and calls for future research on the impacts of demographic and economic dimensions on climate change. We look at the major questions (1) to explore economic and demographic growth, land use and land-cover changes in the context of rapid economic and city growth, and (2) to analyze how the demography and economic growth have been associated with the local air temperature and vegetation. METHOD: We examine urban growth, land use and land-cover changes in the context of rapid economic development and urbanization. We assess the impact of urban expansion on local air temperature and vegetation. The analysis is based on time series data of land use, normalized difference vegetation index (NDVI), and meteorological, demographic and economic data. RESULTS AND DISCUSSION: The results indicate that urban growth has been driven by mass immigration; as a consequence of economic growth and urban expansion, a large amount of farmland has been converted to paved road and residential buildings. Furthermore, the difference between air temperature in urban and exurban areas has increased rapidly. The decrease of high mean annual NDVI has mainly occurred around the dense urban areas.
اظهر المزيد [+] اقل [-]Differential protein profile in zebrafish (Danio rerio) brain under the joint exposure of methyl parathion and cadmium النص الكامل
2012
Ling, Xue-Ping | Lu, Ying-Hua | Huang, He-Qing
As different chemicals, methyl parathion (MP) and cadmium (Cd) can induce neurotoxicity on the brain of aquatic ecosystems. This study aims to explore the differential expression proteins in the brain induced by their joint stress and their joint effects, which are poorly reported, and devotes finding novel biomarkers for monitoring their contamination in water and assessing their neurological effects. The bioaccumulation of MP and Cd in tissues after 96 h of exposure was first analyzed by GC and inductively coupled plasma–MS to provide insights into the interaction. Protein profile changes in the brains of the zebrafish (Danio rerio) exposed to MP and Cd were further investigated using the proteomic approach. The correlation of gene expression on the transcription level of mRNA and the translation level of protein was examined by real-time quantitative PCR and Western blotting analysis. It showed that Cd and MP have an interaction on their bioaccumulation, which suggests that their joint effect over 96 h might be antagonistic. Proteomics revealed that 22 protein spots changed their expression levels under stress, of which 16 proteins were identified using MS. These proteins were involved in oxidation/reduction, metabolism, energy production, receptor activity, and cytoskeleton assembly. Among them, five proteins with a remarkable abundance change are significantly suggested to play important roles in the joint effect. This work demonstrates that there exists an interaction between MP and Cd toxicities, which may aid in our understanding of the mechanism of neurotoxicity induced by joint stress. The results may also provide the possibility of the establishment of candidate biomarkers for monitoring MP and Cd contamination in water.
اظهر المزيد [+] اقل [-]Surface ozone comparison conducted in two rural areas in central-southern Spain النص الكامل
2012
Notario, Alberto | Díaz-de-Mera, Yolanda | Aranda, Alfonso | Adame, José Antonio | Parra, Alfonso | Romero, Eugenio | Parra, Jesús | Muñoz, Fernando
PURPOSE: The purpose of this work is to contribute to the understanding of the photochemical air pollution analysing the levels and temporal variations of surface ozone in two rural areas situated in central-southern Spain. METHOD: The study is based on ozone hourly data recorded during the overall period between January 2008 and November 2009. The seasonal and daily ozone cycles as well as the number of exceedances of the threshold established in the European Ozone Directive have been calculated and analysed. RESULTS: This study presents the first ozone data registered at these two rural sites in the Iberian Peninsula plateau. Ozone shows a clear seasonal variation with the lowest values in January and November. High ozone concentrations are interrelated with high radiation intensities, temperature and wind directions. The information threshold defined in the European Ozone Directives was exceeded six times, while the limit for protection of human health was exceeded more than 40 times. The limits to protect the vegetation were also exceeded. CONCLUSIONS: Porzuna (near Cabañeros National Park) presents higher ozone levels than Argamasilla during the night-time and during the daytime of the summer months. Ozone levels are lower in Argamasilla probably due to fresh emissions from the close industrial area of Puertollano. The ozone exceedances of the limits defined in the Ozone Directive point out an ozone problem in this rural region.
اظهر المزيد [+] اقل [-]Characteristics of an aerobic denitrifier that utilizes ammonium and nitrate simultaneously under the oligotrophic niche النص الكامل
2012
Zhu, Liang | Ding, Wei | Feng, Li-juan | Dai, Xin | Xu, Xiang-yang
INTRODUCTION: An aerobic denitrifier was isolated from the Hua-Jia-Chi pond in China and identified as Pseudomonas mendocina 3-7 (Genbank No. HQ285879). This isolated strain could express periplasmic nitrate reductase which is essential for aerobic denitrification occurred when the dissolved oxygen (DO) level maintains at 3–10 mg L−1. METHODS: To determine whether the ability of isolated strain is exhibited in the bioremediation of polluted drinking source water, the heterotrophic nitrification and aerobic denitrification characteristics of P. mendocina 3-7 under different cultural conditions such as oxygen level, nitrate and organic concentrations were studied from the nitrogenous balance in the paper. RESULTS AND CONCLUSIONS: By measuring the nitrogen balance in all experiments under different culture conditions, the removal of total organic carbon and ammonium was positively correlated with total nitrogen removal, especially under high substrate level. With substrate concentration decreasing, ammonium and nitrate removal occurred separately, and ammonium was completely utilized first under low substrate concentration. Compared to that under high substrate level, the specific growth rate of P. mendocina 3-7 was not low under the low substrate level and the pollutant removal efficiencies remained high, which implies the stronger nitrogen removal and acclimatization capacities of the strain in oligotrophic niches.
اظهر المزيد [+] اقل [-]Degradation of ampicillin antibiotic in aqueous solution by ZnO/polyaniline nanocomposite as photocatalyst under sunlight irradiation النص الكامل
2012
Nosrati, Rahimeh | Olad, Ali | Maramifar, Roya
PURPOSE AND METHOD: ZnO/polyaniline nanocomposite in core–shell structure was prepared by the synthesis and adsorption of polyaniline chains on the structure of ZnO nanoparticles. Fourier transform infrared and ultraviolet–visible (UV–Vis) spectroscopy, X-ray diffraction patterns, field emission scanning electron microscopy, and transmission electron microscopy were used to characterize the composition and structure of the nanocomposite. The nanocomposite was used as an active photocatalyst for photodegradation and removal of ampicillin in aqueous solution. RESULTS: UV–Vis spectroscopy studies showed that ZnO/polyaniline nanocomposite absorbs visible light irradiation as well as ultraviolet spectrum, and therefore, it can be photoactivated under visible and ultraviolet lights. The photocatalytic activity of ZnO/polyaniline nanocomposite in degradation of ampicillin molecules in aqueous solution under natural sunlight irradiation was evaluated and compared with that of ZnO nanoparticles and pristine polyaniline. The ZnO/polyaniline core–shell nanocomposite exhibited higher photocatalytic activity compared to ZnO nanoparticles and pristine polyaniline. The effect of operating conditions (pH, ZnO/polyaniline nanocomposite dosage, and ampicillin concentration) in the photocatalytic degradation of ampicillin using ZnO/polyaniline nanocomposite was investigated. The optimum conditions for maximum efficiency of ampicillin degradation under 120 min sunlight irradiation were found as 10 mg L−1 dosage of ZnO/polyaniline nanocomposite, ampicillin concentration of 4.5 mg L−1, and solution pH = 5. Under optimum operating conditions, degradation efficiency was reached to 41% after 120 min of exposure to the sunlight irradiation.
اظهر المزيد [+] اقل [-]Molecular cloning and expression of novel metallothionein (MT) gene in the polychaete Perinereis nuntia exposed to metals النص الكامل
2012
Won, Eun-Ji | Rhee, Jae-Sung | Ra, Kongtae | Kim, Kyung-Tae | Au, Doris W. T. | Shin, Kyung-Hoon | Lee, Jae-seong
To report a novel metallothionein (MT) gene and evaluate its potency as a biomarker, we clone this MT gene and measured the expression levels in the metal-exposed polychaete Perinereis nuntia. Accumulated metal contents and metallothionein-like proteins (MTLPs), which have been recognized as potential biomarkers, were compared with the relative mRNA expressions of the MT gene of P. nuntia (Pn-MT). In addition, the metal-binding affinity was estimated by recombinant Pn-MT protein. Pn-MT having high cysteine residues with three metal response elements in the promoter region closely clusters with those of other invertebrates. The accumulation patterns of metals were dependent on the exposure times in lead (Pb), cadmium (Cd), and copper (Cu) exposure. Particularly, both MTLP levels and relative mRNA expressions of MT were increased with accumulated metal contents and exposure time in P. nuntia exposed to Pb and Cd. There was no significant modulation of the Pn-MT gene in polychaetes exposed to Zn and As. However, the metal-binding ability of the recombinant Pn-MT protein provides a clear evidence for a high affinity of MT to several metal elements. These results suggest that Pn-MT would play an important role in the detoxification and/or sequestration of specific metals (e.g., Pb and Cd) in P. nuntia and have potential as a molecular biomarker in the monitoring of the marine environment using a polychaete.
اظهر المزيد [+] اقل [-]Lead concentration increase in the hepatic and gill soluble fractions of European chub (Squalius cephalus)—an indicator of increased Pb exposure from the river water النص الكامل
2012
Dragun, Zrinka | Krasnići, Nesrete | Strižak, Željka | Raspor, Biserka
PURPOSE: To examine if chronic exposure of feral fish to elevated Pb concentrations in the river water (up to 1 μg L−1), which are still lower than European recommendations for dissolved Pb in surface waters (7.2 μg L−1; EPCEU (Official J L 348:84, 2008)), would result in Pb accumulation in selected fish tissues. METHODS: Lead concentrations were determined by use of HR ICP-MS in the gill and hepatic soluble fractions of European chub (Squalius cephalus) caught in the Sutla River (Croatia–Slovenia). RESULTS: At the site with increased dissolved Pb in the river water, soluble gill Pb levels (17.3 μg L−1) were approximately 20 times higher compared to uncontaminated sites (0.85 μg L−1), whereas the ratio between contaminated (18.1 μg L−1) and uncontaminated sites (1.17 μg L−1) was lower for liver (15.5). Physiological variability of basal Pb concentrations in soluble gill and hepatic fractions associated to fish size, condition, sex, or age was not observed, excluding the possibility that Pb increase in chub tissues at contaminated site could be the consequence of studied biotic parameters. However, in both tissues of Pb-exposed specimens, females accumulated somewhat more Pb than males, making female chubs potentially more susceptible to possible toxic effects. CONCLUSIONS: The fact that Pb increase in gill and hepatic soluble fractions of the European chub was not caused by biotic factors and was spatially restricted to one site with increased dissolved Pb concentration in the river water points to the applicability of this parameter as early indicator of Pb exposure in monitoring of natural waters.
اظهر المزيد [+] اقل [-]Combined biological processing and microfiltration in the treatment of unhairing wastewater النص الكامل
2012
Mlaik, Najwa | Bouzid, Jalel | Belbahri, Lassad | Woodward, Steve | Mechichi, Tahar
INTRODUCTION: The unhairing step, a part of the beamhouse process, is particularly polluting, generating an alkaline wastewater with high concentrations of organic and inorganic matter. The aim of this study was to evaluate the treatment of this industrial wastewater using a combination of biological and microfiltration processes. MATERIALS AND METHODS: The performance of the activated sludge system (AS) was evaluated under varying organic loading rate (OLR) from 0.9 to 3.4 kg chemical oxygen demand (COD) m−3 day−1 and decreasing hydraulic retention time (HRT) from 3 to 1.6 days. RESULTS: For an HRT of 3 days, the increase of OLR significantly affected the removal of organic matter. Therefore, the biological organic matter removal of unhairing wastewater decreased from 92% to 66% for COD and from 87 to 53% for biological oxygen demand (BOD5). GC-MS analyses showed that biological treatment of unhairing wastewater contributed to the removal of long chain fatty acids and their degradation products. Microfiltration of unhairing wastewater was performed using 0.2 μm pore-size membranes in tangential filtration. The highest removal efficiencies were obtained for bacteria (100%) and turbidity (98.4%) which confirmed the importance of the microfiltration step in treatment of unhairing wastewater. The result showed that the flux decay rate was greatest at the start of the microfiltration assay (90 L h−1 m2), becoming 60.7 L h−1 m2 after 32 min. CONCLUSION: This change indicated that fouling occurred rapidly once the membrane module was put into operation.
اظهر المزيد [+] اقل [-]Mercury policy and regulations for coal-fired power plants النص الكامل
2012
Rallo, Manuela | Lopez-Anton, M Antonia | Contreras, M Luisa | Maroto-Valer, M Mercedes
INTRODUCTION: Mercury is a high-priority regulatory concern because of its persistence and bioaccumulation in the environment and evidence of its having serious adverse effects on the neurological development of children. DISCUSSION: Mercury is released into the atmosphere from both natural and anthropogenic sources. Coal-fired utilities are considered to be one of the largest anthropogenic mercury emission sources. The period since the late 1990s has been marked by increasing concern over mercury emissions from combustion systems to the extent that a number of national governments have either already implemented or are in the process of implementing, legislation aimed at enforcing tighter control over mercury emissions and a reduction in mercury consumption. CONCLUSION: This review examines the most important national and international policies and agreements for controlling mercury emissions from coal-fired combustion systems. To provide a global perspective, this study lists the countries with the largest estimated mercury emissions and regulatory efforts to reduce them.
اظهر المزيد [+] اقل [-]