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Determination of Vanadium Levels in Seafood Using Dispersive Liquid-Liquid Microextraction and Optical Sensors
2015
Santos, Analu Pires | Lemos, Valfredo Azevedo
In this study, we developed a new method for the preconcentration and spectrophotometric determination of vanadium (V) using dispersive liquid-liquid microextraction (DLLME) and optical sensors using 4-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) as a complexing reagent. The preconcentration is based on the extraction of vanadium ions (V) in trichloroethylene in the form of a complex with Br-PADAP, using ethanol as a dispersion solvent. After injecting the solvent into a solution containing vanadium, a homogeneous mixture is obtained. The mixture is centrifuged to deposit the desired phase onto a triacetylcellulose membrane. Then, the supernatant is discarded, and the membrane is exposed to the radiation beam of a spectrophotometer without the use of a microcuvette. Under optimal conditions, the detection limit was determined to be 0.57 μg L⁻¹, and the quantification limit was 1.91 μg L⁻¹. The accuracy of the method was verified by analyzing a certified reference material, BCR®414, plankton. The procedure was applied to the determination of vanadium levels in shellfish samples, specifically shrimp and oyster.
Afficher plus [+] Moins [-]Effect of Glyphosate on Enzymatic Activities, Rhizobiaceae and Total Bacterial Communities in an Agricultural Tunisian Soil
2015
Cherni, Ala Edine | Trabelsi, Darine | Chebil, Samir | Barhoumi, Fethi | Rodríguez-Llorente, Ignacio D. | Zribi, Kais
The effect of glyphosate on richness and structure of the Rhizobiaceae and total bacterial communities in an agricultural soil after different treatments was studied. The herbicide was applied on the soil in the presence or the absence of Medicago sativa plants with or without inoculation with the Sinorhizobium meliloti reference strain RCR2011. Terminal-restriction fragment length polymorphism (T-RFLP) profiling showed that this agricultural soil has a high total microbial and rhizobial genetic diversity. To investigate the impact of the herbicide on microbial activity, fluorescein diacetate (FDA) and a panel of three enzymes (phosphatase, catalase, and protease BAA) were assessed. Depending on the type of enzyme tested, the enzymatic activities responded differently to the action of glyphosate, the presence of M. sativa, and the inoculation with RCR2011. The present work gives original insights into the effect of the herbicide on the rhizospheric area of M. sativa with or without rhizobial inoculation by the fact that glyphosate changes microbial diversity and affects soil enzymatic activities.
Afficher plus [+] Moins [-]Peatland Microbial Communities as Indicators of the Extreme Atmospheric Dust Deposition
2015
Fiałkiewicz-Kozieł, B. | Smieja-Król, B. | Ostrovnaya, T. M. | Frontasyeva, M. | Siemińska, A. | Lamentowicz, M.
We investigated a peat profile from the Izery Mountains, located within the so-called Black Triangle, the border area of Poland, Czech Republic, and Germany. This peatland suffered from an extreme atmospheric pollution during the last 50 years, which created an exceptional natural experiment to examine the impact of pollution on peatland microbes. Testate amoebae (TA), Centropyxis aerophila and Phryganella acropodia, were distinguished as a proxy of atmospheric pollution caused by extensive brown coal combustion. We recorded a decline of mixotrophic TA and development of agglutinated taxa as a response for the extreme concentration of Al (30 g kg⁻¹) and Cu (96 mg kg⁻¹) as well as the extreme amount of fly ash particles determined by scanning electron microscopy (SEM) analysis, which were used by TA for shell construction. Titanium (5.9 %), aluminum (4.7 %), and chromium (4.2 %) significantly explained the highest percentage of the variance in TA data. Elements such as Al, Ti, Cr, Ni, and Cu were highly correlated (r > 0.7, p < 0.01) with pseudostome position/body size ratio and pseudostome position. Changes in the community structure, functional diversity, and mechanisms of shell construction were recognized as the indicators of dust pollution. We strengthen the importance of the TA as the bioindicators of the recent atmospheric pollution.
Afficher plus [+] Moins [-]No delayed behavioral and phenotypic responses to experimental early-life lead exposure in great tits (Parus major)
2015
Ruuskanen, Suvi | Eeva, Tapio | Kotitalo, Päivi | Stauffer, Janina | Rainio, Miia
Early-life exposure to pollutants, such as lead, may have long-lasting consequences on health, behavior, and cognition. However, experiments on delayed effects of specific pollutants are very rare in wild animals. We experimentally exposed wild nestling great tits (Parus major) to dietary lead (high, low, or control group) in levels relevant to exposure levels of wild populations in Europe and studied delayed effects on phenotypic and behavioral traits in captivity. We also included a group of birds from a vicinity of a copper smelter, exposed to a mixture of toxic metals and altered food supply during development. This experimental setup allowed us to compare the strength of direct (exposure to lead per se) and indirect (pollution-related changes in diet) effects of pollutants. Our experimental lead treatment significantly increased lead levels in bone and feces compared with controls. However, we found no carry-over effect of early-life dietary lead on morphology, plumage coloration, or heat shock proteins. Treatment did not affect activity, exploration, neophobia, or success in learning and spatial memory task. We conclude that with the exposure levels and relatively short exposure period used, delayed effects on the measured traits were not found. However, it is important to further study other types of behavioral traits and ultimately fitness effects.
Afficher plus [+] Moins [-]Removal of Decachlorobiphenyl in Vermicomposting Process Amended with Rabbit Manure and Peat Moss
2015
This study aimed to evaluate the removal of polychlorinated biphenyls, with a vermicomposting system, using the following as components: the earthworm Eisenia fetida, peat moss and rabbit excrement and a compound called decachlorobiphenyl, for a period of 91 days under non-sterile conditions. The results obtained were a removal of decachlorobiphenyl 79.6 % with an initial concentration of 100 mg L⁻¹, 89.7 % with 150 mg L⁻¹and 95.38 % with 200 mg L⁻¹; the earthworms bioaccumulated less than 5 mg L⁻¹in all concentrations of decachlorobiphenyl analysed without apparent toxic effect. Weight gain was observed in earthworms that assimilated contaminant during vermicomposting, as the number of cocoons produced in contrast to the control in which both the weight and the number of cocoons were lower. To our knowledge, this is the first study which suggests that vermicomposting may be a suitable mechanism for removal of decachlorobiphenyl with high recalcitrance from contaminated sediment or soils.
Afficher plus [+] Moins [-]Biodegradation and Identification of Transformation Products of Fluorene by Ascomycete Fungi
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 [-]Tree Growth and Climate Relationship: Dynamics of Scots Pine (Pinus Sylvestris L.) Growing in the Near-Source Region of the Combined Heat and Power Plant During the Development of the Pro-Ecological Strategy in Poland
2015
Since the 1990s, the emission of pollutants was reduced in a majority of Polish and developing country factories whereas the level of energy production was similar to that prior to the 1990s. The conifer investigated in this study has grown for many years under the stress of industrial pollution. Despite this, the trees are preserved, to a large extent, sensitive to the natural climatic factors. We present a complex analysis of the climatic (sunshine, temperature, precipitation, humidity, and wind circulation) and anthropogenic factors influencing the radial increment dynamics of Scots pine (Pinus sylvestris L.) growing in the vicinity of the combined heat and power station in Łaziska (Poland). We analyzed the spatiotemporal distribution of growth reductions, the depth of reduction with respect to the distance from the emitter, the relationship between tree growth and climate during the industry development period and during proecological strategy application . Samples of carbon isotopic composition in pine needles from 2012 to 2013 were additionally determined. Pines series of 3 positions indicate that they have a similar sensitivity to most climatic elements of the previous and given year, but there is also a different rhythm between the studied populations of incremental growth of pines. The causes of diversity are due to the different types of habitat (site types) and industrial pollution. The variation in carbon stable isotopic composition in pine needles was connected with an increase of CO₂.
Afficher plus [+] Moins [-]Combining Passive Sampling with a GC-MS-Database Screening Tool to Assess Trace Organic Contamination of Rivers: a Pilot Study in Melbourne, Australia
2015
This study assessed the suitability of passive sampler extracts for use with a GC-MS-database rapid screening technique for around 940 organic chemicals. Chemcatcher™ passive sampler systems containing either Empore™ SDB-XC or C18FF disks were deployed at 21 riverine sites in and near Melbourne, Victoria, Australia, for a period of 28 days during September–October 2008. Methanolic elution of the SDB-XC and C18FF disks produced an extract that, after evaporation and inversion into hexane, was compatible with the GC-MS-database method enabling over 30 chemicals to be observed. The sources of the non-agricultural chemicals are still unclear, but this study was conducted in a relatively dry season where total rainfall was approximately 40 % lower than the long-term mean for the catchment during the study period. Thus, the risks may be greater in wetter seasons, as greater quantities of chemicals are likely to reach waterways as the frequency, extent and intensity of surface run-off events increase. This study provides valuable information for policy and decision-makers, both in Australia and other regions of the world, in that passive sampling can be conveniently used prior to analysis by multi-residue techniques to produce data to assess the likely risks trace organic chemicals pose to aquatic ecosystems.
Afficher plus [+] Moins [-]Reduction of Nitrate in Groundwater by Fe(0)/Magnetite Nanoparticles Entrapped in Ca-Alginate Beads
2015
(Franklin W.),
Calcium alginate beads entrapping a mixture of Fe(0) and nanosized magnetite (NMT) were prepared and evaluated for their capability to reduce nitrate in groundwater. Microscopic and spectroscopic analyses of the beads revealed that clusters of Fe(0)/NMT were entirely embedded in alginate polymer matrix containing a large number of carboxylic and hydroxyl functional groups. The extent of nitrate reduction increased with increasing content of Fe(0) and NMT in the beads, but there was a critical NMT mass limit relative to Fe(0) mass where no further increase in nitrate reduction occurred. The beads showed slower nitrate reduction kinetics than bare Fe(0)/NMT but had comparable capacity in overall nitrate removal. Nitrate reduction increased proportionally with an increase in bead dosage to give a maximum removal of 94.5 % at 37.5 g L⁻¹ in 48 h. Nitrate reduction with 50 g L⁻¹ beads achieved completion of two reduction cycles in 72 h to reduce 2.19 mM nitrate to less than 0.71 mM (10 mg-N L⁻¹) in each cycle. The overall results demonstrated that the beads developed in this study have a potential utility in remediation of nitrate in groundwater.
Afficher plus [+] Moins [-]Bactericidal Performance of Chlorophyllin-Copper Hydrotalcite Compounds
2015
Rocha Oliveira, Gabriele | Dias do Amaral, Laricy Janaína | Giovanela, Marcelo | da Silva Crespo, Janaina | Fetter, Geolar | Rivera, José Angel | Sampieri, Alvaro | Bosch, Pedro
Copper hydrotalcites with and without adsorbed chlorophyllin exhibit a bactericidal effect that depends on the copper release and the basicity, which can be tuned through the chlorophyllin adsorption. The prepared solids performed well for the elimination of Escherichia coli, Enterobacter aerogenes, Salmonella enterica, and Staphylococcus aureus bacteria. The results showed that the copper-containing hydrotalcite with the adsorbed chlorophyllin is the most active material. Wastewaters from a metal industry were treated with these hybrid compounds, and the bactericidal effect was comparable with the results reported using more complex methods such as photocatalysis. Furthermore, one main advantage of these hybrid compounds is its low human toxicity compared with silver-containing materials.
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