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Результаты 1021-1030 из 1,273
Influence of Airborne Pollution on Cd, Zn, Pb, Cu, and Al Accumulation and Physiological Parameters of Plant Leaves in Antakya (Turkey)
2011
Doğanlar, Zeynep Banu | Atmaca, Mustafa
In this study, the effects of industrial and urban pollution on Pb, Al, Cd, Cu, and Zn accumulation, peroxidase activity, and pigment and protein contents were investigated in shrub and tree leaves in Antakya, Turkey. We determined that industrial and traffic activities produce the most plant-incorporated air pollutants in Antakya City. Cu and Al amounts were high in plants in the urban street location and Cd, Pb, and Zn amounts where high for all plants in the industrial site. Acer negundo L. showed maximum Pb and Zn accumulation at the industrial site and Al accumulation for the urban street site. Higher Cd and Cu amounts were detected in Platanus orientalis L. and Nerium oleander L. in the industrial and urban street sites, respectively. Compared to the control site, decreases in pigment and total soluble protein contents and increases in peroxidase enzyme activity were more evident in industrial and urban street sites. Our results indicated that industry and urban air pollution is high in Antakya City and Pb pollution was at an especially alarming level for vegetation and human health.
Показать больше [+] Меньше [-]Effects of Vegetation in Mitigating the Toxicity of Pesticide Mixtures in Sediments of a Wetland Mesocosm
2011
Lizotte, Richard E., Jr | Moore, Matthew T. | Locke, Martin A. | Kroger, Robert
This study assessed effects of a mixture of two pesticides, diazinon and permethrin, on 48-h sediment toxicity to Hyalella azteca in a constructed wetland mesocosm containing non-vegetated and vegetated sections. Sediment samples were collected at inflow, middle, and back points within each section 5, 24, 72 h, 7, 14, and 21 days post-amendment. Pesticides were detected in sediments throughout non-vegetated and vegetated wetland sections. H. azteca 48-h survival varied across sampling period, wetland location, and vegetation type with lowest survival occurring within the first 72 h of the inflow and middle locations of the non-vegetated section. Sediment toxicity was ameliorated by 14 and 7 days within the non-vegetated and vegetated sections, respectively. Relationships between pesticide concentrations and animal survival indicated toxicity was from both diazinon and cis-permethrin in the non-vegetated section and primarily cis-permethrin in the vegetated section. Results show that vegetation ameliorated pesticide mixture 48-h sediment toxicity to H. azteca earlier and to a greater extent than non-vegetated constructed wetlands. A 21-day retention time is necessary to improve 48-h H. azteca sediment survival to ≥90% in wetlands of this size.
Показать больше [+] Меньше [-]Uptake and Accumulation of Anthropogenic Os in Free-Living Bank Voles (Myodes glareolus)
2011
Rodushkin, Ilia | Engström, Emma | Sörlin, Dieke | Baxter, Douglas | Hörnfeldt, Birger | Nyholm, Erik | Ecke, Frauke
Osmium tetroxide (OsO4) is one of the most toxic air contaminants but its environmental effects are poorly understood. Here, for the first time, we present evidence of osmium uptake in a common herbivore (bank vole, Myodes glareolus) in boreal forests of northern Sweden. Voles (n = 22) and fruticose arboreal pendular lichens, the potential main winter food source of the vole, were collected along a spatial gradient to the west of a steelwork in Tornio, Finland at the Finnish–Swedish border. 187Os/188Os isotope ratios increased and osmium concentrations decreased in lichens and voles along the gradient. Osmium concentrations in lichens were 10,000-fold higher than those in voles. Closest to the steelwork, concentrations were highest in kidneys rather than skin/fur that are directly exposed to airborne OsO4. The kidney-to-body weight ratio was higher at the two localities close to the steelwork. Even though based on a small sample size, our results for the first time demonstrate that osmium is taken up, partitioned, and accumulated in mammal tissue, and indicate that high kidney-to-body weight ratios might be induced by anthropogenic osmium.
Показать больше [+] Меньше [-]Methane Fluxes from Alpine Wetlands of Zoige Plateau in Relation to Water Regime and Vegetation under Two Scales
2011
Chen, Huai | Wu, Ning | Wang, Yanfen | Gao, Yongheng | Peng, Changhui
Methane fluxes in alpine ecosystems remain insufficiently studied, especially in terms of the magnitude, temporal, and spatial patterns. To quantify the mean methane emission of alpine ecosystems, methane fluxes were measured among six ecosystems and microsites within each ecosystem at Zoige National Wetland Reserve. The average methane emission from Zoige Plateau was 2.25 mg CH4 m−2 h−1, which fell into the range of methane emission rate reported by a number of studies in other alpine wetlands. Prevailing ecosystem types had important impacts on the methane flux on the landscape scale. In the wet ecosystems, the microsites had different methane emissions resulting from the differences in the depth of water table and associated vegetation characteristics. The identification of the microsites based on their vegetation characteristics thus allows upscaling of methane emissions in these ecosystems. However, in the dry ecosystems showing even methane uptake, the spatial variation in the methane fluxes was low and the vegetation has a poor predicative value for the methane fluxes. There, the soil porosity linked to the gas diffusion rate in soil would be the key factor explaining methane fluxes.
Показать больше [+] Меньше [-]Transport of Strontium Through a Ca-bentonite (Almería, Spain) and Comparison with MX-80 Na-bentonite: Experimental and Modelling
2011
Valderrama, César | Giménez Gracia, Javier | De Pablo, Joan | Martinez, Maria
In this work, the sorption of strontium on a Ca-bentonite (CGA) from Almería (Spain) in column experiments was studied, and the results obtained were compared with the sorption onto the Na-bentonite (MX-80). The code CTXFIT (two site non-equilibrium sorption model) was used in order to fit the experimental data and to determine sorption and transport parameters. The effect of inlet Sr(II) initial concentration and the ionic strength were evaluated. The results obtained showed that the sorption capacities as well as the transport and sorption parameters of both bentonites were affected by the initial metal concentration. In experiments with higher inlet concentrations, columns were saturated faster, leading to shorter breakthrough and exhaustion times. On the other hand, a decrease of sorption and transport parameters was observed at higher ionic strengths, which would confirm ion exchange as the main mechanism of Sr(II) sorption onto both bentonites. The sorption parameters (sorption capacity and retardation factor) obtained indicated that the Ca-bentonite from Almería (Spain) presented better sorption performance than the Na-bentonite, which was related to the physical properties of the Ca-bentonite.
Показать больше [+] Меньше [-]Surface Soil Geochemistry for Environmental Assessment in Kavala Area, Northern Greece
2011
Papastergios, Georgios | Filippidis, Anestis | Fernandez-Turiel, Jose-Luis | Gimeno, Domingo | Sikalidis, Constantinos
The aim of the present study was to estimate the geochemical background and anomaly threshold values of the surface soils in Kavala, northern Greece. In order to reach this goal, a simple and practical procedure was applied. This procedure included the extraction of 42 major and trace elements by analytical grade HNO3 from 65 surface soil samples, analysis by inductively coupled plasma–optical emission spectrometry and inductively coupled plasma–mass spectrometry, the distribution of the elemental data displayed on probability graphs (Q-Q plots), and the visualization of the results spatially by GIS software. The results indicated that natural factors mostly influence the elevated concentrations of Al, Ca, Fe, K, Mg, Si, B, Ba, Ce, Ga, Ge, La, Li, Mn Rb, Sb, Se, Sn, Sr, Y, and Zr, while anthropogenic activities mostly influence the elevated concentrations of Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mo, Ni, Pb, Th, Ti, U, V, W, and Zn. Nevertheless, almost all the elements determined showed their elevated concentrations inside the industrial part of Kavala area, which implies that the anthropogenic activities taking place in the study area, influence importantly the spatial distribution of the elements. The methodology followed in this research seems to be an adequate alternative for soil environmental studies.
Показать больше [+] Меньше [-]Studies in a Fixed-Bed Photocatalytic Reactor System Using Natural Materials for Degradation of a Dye Contaminant in Water
2011
Esparza, P. | Borges, M. E. | Díaz, L.
A fixed-bed photocatalytic reactor equipped with a cylindrical parabolic light concentrator was studied to remove organic dyes from water using natural volcanic ashes particles and nanostructured titania supported on volcanic ashes as photocatalytic materials. The influences of flow rate, photocatalyst and photocatalytic material adsorption capacity were studied. A fixed-bed photocatalytic reactor was designed and built in the laboratory; a methylene blue aqueous solution, used as model compound for dye contaminated water, was fed into the reactor. Methylene blue destruction efficiencies were monitored spectrophotometrically. Combined effects of dye adsorption and photodecomposition on photocatalyst were studied and compared by infrared spectroscopy.
Показать больше [+] Меньше [-]Ibuprofen Genotoxicity in Aquatic Environment: An Experimental Model Using Oreochromis niloticus
2011
Ragugnetti, Marilaine | Adams, Mônica L. | Guimarães, Ana T. B. | Sponchiado, Graziela | de Vasconcelos, Eliane Carvalho | de Oliveira, Cíntia Mara Ribas
Medicines and their metabolites have been found as water contaminants at very low concentrations; moreover, there is no extensive toxicological data to determine the risks associated with their occurrence in water resources. The ibuprofen genotoxicity potential to the Oreochromis niloticus fish (Tilapia), due to nanograms per liter exposure, was evaluated using the micronucleus test. Acute (48 h) and sub-chronic assays (10 days) were carried out at 300 ng/L ibuprofen aquatic concentration comparing with the negative control group (without treatment), with eight animals per group. The results were assessed from the average of triplicate analyses. The micronucleus frequency in peripheral blood of fish was determined using a sample size of 3,000 erythrocytes per animal. Significance was defined using t test (p ≤ 0.05). The bioassay results showed a statistically significant increase in the frequency of micronuclei for both exposure times in comparison to the negative control. The micronucleus frequency observed for the sub-chronic tests was higher than the one identified in the acute assays. The observed ibuprofen genotoxic effects demonstrated an aquatic environmental risk of this pharmaceutical, which occurs for the used fish experimental model in lower concentration than previously described for other aquatic organisms.
Показать больше [+] Меньше [-]Ectogenic Meromixis of Lake Hallstättersee, Austria Induced by Waste Water Intrusions from Salt Mining
2011
Ficker, Harald | Gassner, Hubert | Achleitner, Daniela | Schabetsberger, Robert
Lake Hallstättersee is a holomictic alpine lake, which is influenced by salt mining since the middle Bronze Age. Beside the constant saline waste water load, two massive brine spills loaded the lake with additional 16,900Â tons sodium chloride (≈10,250Â tons Cl−) from 1977 to 1979 and 3,000Â tons salt (≈1,820Â tons Cl−) in 2005. The effect of waste water intrusions from salt mining on stratification of Lake Hallstättersee was analysed over a period of 40Â years. Water density, dissolved oxygen and total phosphorus (TP) concentrations were measured and an exponential model was fitted to describe the wash-out of chloride from Lake Hallstättersee after the brine spills. Furthermore, the time required returning to holomixis and steady chloride content after the second brine spill was estimated. During the whole sampling period the minimum and maximum volume-weighted annual mean chloride concentrations were 23.58Â mg/L in 1979 and 3.19Â mg/L in 1998. However, the mixing regime of Lake Hallstättersee, as well as the chloride concentrations, varied considerably and exhibited three holomictic and three meromictic periods between 1970 and 2009. Holomictic periods were observed when the yearly density gradient was below 0.06Â kg/m3, deepwater oxygen in spring above 4Â mg/L and consequently declining TP concentration in the deepest water layer below 60Â mg/m3, otherwise meromictic periods were observed. Our study showed that Hallstättersee was 13Â years ectogenic meromictic and 27Â years holomictic during the study period.
Показать больше [+] Меньше [-]Screening of Microorganisms for Biodegradation of Simazine Pollution (Obsolete Pesticide Azotop 50 WP)
2011
Błaszak, Magdalena | Pełech, Robert | Graczyk, Paulina
The capability of environmental microorganisms to biodegrade simazine—an active substance of 2-chloro-s-triazine herbicides (pesticide waste since 2007)—was assessed. An enormous metabolic potential of microorganisms impels to explore the possibilities of using them as an alternative way for thermal and chemical methods of utilization. First, the biotope rich in microorganisms resistant to simazine was examined. Only the higher dose of simazine (100Â mg/l) had an actual influence on quantity of bacteria and environmental fungi incubated on substrate with simazine. Most simazine-resistant bacteria populated activated sludge and biohumus (vermicompost); the biggest strain of resistant fungi was found in floral soil and risosphere soil of maize. Compost and biohumus were the sources of microorganisms which biodegraded simazine, though either of them was the dominant considering the quantity of simazine-resistant microorganisms. In both cases of periodic culture (microorganisms from biohumus and compost), nearly 100% of simazine (50Â mg/l) was degraded (within 8Â days). After the repeated enrichment culture with simazine, the rate of its degradation highly accelerated, and just after 24Â h, the significant decrease of simazine (20% in compost and 80% in biohumus) was noted. Although a dozen attempts of isolating various strains responsible for biodegradation of simazine from compost and biohumus were performed, only the strain identified as Arthrobacter urefaciens (NC) was obtained, and it biodegraded simazine with almost 100% efficiency (within 4Â days).
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