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Résultats 1711-1720 de 1,908
An evaluation approach for livable urban environments
2013
Chiang, Chia-Ling | Liang, Jeng-Jong
This study proposes a method for evaluating livable urban environments using the analytic hierarchy process, a survey of public opinions (n = 1,075), and gray relational analysis with a pollutant standards index to estimate the weights of weather, air pollution, and environment aspects and each respective factor. This study investigates the positive or negative correlation of these factors and their effects on livable environment. A value of 100 was designated as the perfect living condition. Results show that the weights of weather, air pollution, and environment aspects were 0.288, 0.395, and 0.317, respectively. The weight ranges of three weather factors, five air pollution factors, and ten environmental factors were 0.311-0.358, 0.191-205, and 0.081-0.116, respectively. The monthly livable index of 28 districts in Taichung City and of 20 cities/counties in Taiwan ranged from 81.1 to 92.4 and from 83.1 to 90.8 in different months, respectively, showing that environmental aspect played a key role. These results demonstrate that the proposed method can provide a quantification index of living conditions in each region, thereby establishing the governmental improvement policy firmly. This study also presents a discussion on improvement strategies, especially on the apportionment rate of governmental construction funds for livable urban environments.
Afficher plus [+] Moins [-]Seizure modeling of Pb(II) and Cd(II) from aqueous solution by chemically modified sugarcane bagasse fly ash: isotherms, kinetics, and column study
2013
Shah, Bhavna | Mistry, Chirag | Shah, Ajay
Heavy metal pollution is a common environmental problem all over the world. The purpose of the research is to examine the applicability of bagasse fly ash (BFA)—an agricultural waste of sugar industry used for the synthesis of zeolitic material. The zeolitic material are used for the uptake of Pb(II) and Cd(II) heavy metal. Bagasse fly ash is used as a native material for the synthesis of zeolitic materials by conventional hydrothermal treatment without (conventional zeolitic bagasse fly ash (CZBFA)) and with electrolyte (conventional zeolitic bagasse fly ash in electrolyte media (ECZBFA)) media. Heavy metal ions Pb(II) and Cd(II) were successfully seized from aqueous media using these synthesized zeolitic materials. In this study, the zeolitic materials were well characterized by different instrumental methods such as Brunauer–Emmett–Teller, XRF, Fourier transform infrared spectroscopy, powder X-ray diffraction, and scanning electron microscopic microphotographs. The presence of analcime, phillipsite, and zeolite P in adsorbents confirms successful conversion of native BFA into zeolitic materials. Seizure modeling of Pb(II) and Cd(II) was achieved by batch sorption experiments, isotherms, and kinetic studies. These data were used to compare and evaluate the zeolitic materials as potential sorbents for the uptake of heavy metal ions from an aqueous media. The Langmuir isotherm correlation coefficient parameters best fit the equilibrium data which indicate the physical sorption. Pseudo-second-order and intra-particle diffusion model matches best which indicates that the rate of sorption was controlled by film diffusion. The column studies were performed for the practical function of sorbents, and breakthrough curves were obtained, which revealed higher sorption capacity as compared to batch method. Synthesized zeolitic material (CZBFA and ECZBFA), a low-cost sorbent, was proven as potential sorbent for the uptake of Pb(II) and Cd(II) heavy metal ions.
Afficher plus [+] Moins [-]Prioritisation of organic contaminants in a river basin using chemical analyses and bioassays
2013
Smital, Tvrtko | Terzić, Senka | Lončar, Jovica | Senta, Ivan | Žaja, Roko | Popović, Marta | Mikac, Iva | Tollefsen, Knut-Erik | Thomas, Kevin V. | Ahel, Marijan
Region-specific contaminant prioritisation is an important prerequisite for sustainable and cost-effective monitoring due to the high number of different contaminants that may be present. Surface water and sediment samples from the Sava River, Croatia, were collected at four locations covering a 150-km-long river section characterised by well-defined pollution gradients. Analysis of contaminant profiles along the pollution gradients was performed by combining toxicity screening using a battery of small-scale or in vitro bioassays, which covered different modes of action, with detailed chemical characterisation based on gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). A large number of contaminants, belonging to different toxicant classes, were identified in both analysed matrices. Analyses of water samples showed that contaminants having polar character occurred in the highest concentrations, while in sediments, contributions from both non-polar and amphiphilic contaminants should be taken into account. Estimated contributions of individual contaminant classes to the overall toxicity indicated that, besides the classical pollutants, a number of emerging contaminants, including surfactants, pharmaceuticals, personal care products and plasticizers, should be taken into consideration in future monitoring activities. This work demonstrates the importance of the integrated chemical and bioanalytical approach for a systematic region-specific pollutant prioritisation. Finally, the results presented in this study confirm that hazard assessment in complex environmental matrices should be directed towards identification of key pollutants, rather than focusing on a priori selected contaminants alone.
Afficher plus [+] Moins [-]Impact of Zn–Pb mining in the Olkusz ore district on the Permian aquifer (SW Poland)
2013
Motyka, Jacek | Postawa, Adam
Long-term extensive mining of Zn–Pb ores in the Olkusz area resulted in significant changes of water table levels and chemical composition of water in all aquifers in this area. Within the Permian aquifer, hydrochemical type of water evolved in two general stages. Short-term effect was freshening in the zones of contact with overlying the Triassic limestones and dolomites. Long-term effect was a change in flow pattern and, as a consequence, an inflow of naturally altered and antropogenically contaminated water from the Triassic aquifer into the Permian complex. This was especially intensive in densely fissured and fault zones. As a result of all these processes, hydrochemical type of water shifted from multi-ion types with various combinations of ions towards higher shares of sulphates, calcium and magnesium.
Afficher plus [+] Moins [-]Behaviour and variability of local and regional oxidant levels (OX = O₃ + NO ₂) measured in a polluted area in central-southern of Iberian Peninsula
2013
Notario, Alberto | Bravo, Iván | Adame, José Antonio | Díaz-de-Mera, Yolanda | Aranda, Alfonso | Rodríguez, Ana | Rodriguez, Diana
The purpose of this work is to contribute to the understanding of the photochemical air pollution in central-southern of the Iberian Peninsula, analysing the behaviour and variability of oxidant levels (OX = O₃ + NO₂), measured in a polluted area with the highest concentration of heavy industry in central Spain. A detailed air pollution database was observed from two monitoring stations. The data period used was 2008 and 2009, around 210,000 data, selected for its pollution and meteorological statistics, which are very representative of the region. Data were collected every 15 min, however hourly values were used to analyse the seasonal and daily ozone, NO, NO₂ and OX cycles. The variation of OX concentrations with NO ₓ is investigated, for the first time, in the centre of the Iberian Peninsula. The concentration of OX was calculated using the sum of a NO ₓ -independent ‘regional’ contribution (i.e. the O₃ background), and a linearly NO ₓ -dependent ‘local’ contribution. Monthly dependence of regional and local OX concentration was observed to determine when the maximum values may be expected. The variation of OX concentrations with levels of NO ₓ was also measured, in order to pinpoint the atmospheric sources of OX in the polluted areas. The ratios [NO₂]/[OX] and [NO₂]/[NO ₓ ] vs. [NO ₓ ] were analysed to find the fraction of OX in the form of NO₂, and the possible source of the local NO ₓ -dependent contribution, respectively. The progressive increase of the ratio [NO₂]/[OX] with [NO ₓ ] observed shows a greater proportion of OX in the form of NO₂ as the level of NO ₓ increases. The higher measured values in the ratio [NO₂]/[NO ₓ ] should not be attributed to NO ₓ emissions by vehicles; they could be explained by industrial emission, termolecular reactions or formaldehyde and HONO directly emitted by vehicles exhausts. We also estimate the rate of NO₂ photolysis, J NO₂ = 0.18–0.64 min⁻¹, a key atmospheric reaction that influence O₃ production and then the regional air quality. The first surface plot study of annual variation of the daily mean oxidant levels, obtained for this polluted area may be used to improve the atmospheric photochemical dynamic in this region of the Iberian Peninsula where there are undeniable air quality problems.
Afficher plus [+] Moins [-]Biostimulation of the autochthonous microbial community for the depletion of polychlorinated biphenyls (PCBs) in contaminated sediments
2013
Di Gregorio, Simona | Azaizeh, Hassan | Lorenzi, Roberto
In this study, the effect of the biostimulation of the autochthonous microbial community on the depletion of polychlorinated biphenyls (PCBs) in historically contaminated sediments (6.260 ± 9.3 10⁻³ μg PCB/ g dry weight) has been observed. Biostimulation consisted of (1) the amendment of an electron donor to favor the dehalogenation of the high-chlorinated PCBs and (2) the vegetation of sediments with Sparganium sp. plants to promote the oxidation of the low-chlorinated PCBs by rhizodegradation. The effects of the treatments have been analyzed in terms of both PCB depletion and changes of the autochthonous bacterial community structure. The relative abundance of selected bacterial groups with reference to untreated sediments has been evaluated by quantitative real-time PCR. The amendment of acetate determined the enrichment of anaerobic dechlorinators like Dehalococcoides sp. Vegetation with Sparganium sp. plants determined the enrichment of either (3) the dechlorinators, Dehalococcoides and the Chloroflexi o-17/DF-1 strains or (4) the Acidobacteria, β-Proteobacteria, Actinobacteria, α-Proteobacteria, Bacteroidetes, and Firmicutes. The combination of the two biostimulation strategy determined the 91.5 % of abatement of the initial PCB content.
Afficher plus [+] Moins [-]Partitioning of nutrients and micropollutants along the sludge treatment line: a case study
2013
Gianico, A. | Braguglia, C. M. | Mascolo, G. | Mininni, G.
A 2-year sampling campaign was conducted in three wastewater treatment plants of various sizes in the Rome area to assess the occurrence of nutrients and micropollutants among primary, secondary and digested sludge. The primary purpose was to evaluate the quality of different sludge types and their suitability for agricultural use. Primary sludge was consistently more polluted than secondary in terms of organic micropollutants, whereas heavy metals partitioned equally among the sludge types. In digested sludge, the heavy metal concentrations were always below limit values proposed for agricultural utilisation. In contrast, organic micropollutants concentrated during anaerobic digestion and affected the quality of the digested sludge. Secondary sludge resulted less polluted and richer in nitrogen and phosphorus (up to three times) than primary sludge and is hence more suitable for agricultural use. Separate processing of primary and secondary sludge might therefore be an innovative option for sludge management that could maximise the possibilities of agricultural use of secondary sludge and limit disposal problems only to primary sludge. In fact, primary sludge could be easily treated and disposed of by conventional processes including thickening, anaerobic digestion, centrifugation and incineration, whereas the difficult digestibility of secondary sludge could be improved by disintegration pre-treatment before stabilisation.
Afficher plus [+] Moins [-]Kinetics of Remazol Black B adsorption onto carbon prepared from sugar beet pulp
2013
Dursun, Arzu Y. | Tepe, Ozlem | Uslu, Gülşad | Dursun, Gülbeyi | Saatci, Yusuf
Dried sugar beet pulp, an agricultural solid waste, was used for the production of carbon. Carbonised beet pulp was tested in the adsorption of Remazol Black B dye, and adsorption studies with real textile wastewater were also performed. Batch kinetic studies showed that an equilibrium time of 180 min was needed for the adsorption. The maximum dye adsorption capacity was obtained as 80.0 mg g⁻¹ at the temperature of 25 °C at pH = 1.0. The Langmuir and Freundlich adsorption models were used for the mathematical description of the adsorption equilibrium, and it was reported that experimental data fitted very well to the Langmuir model. Mass transfer and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate-controlling steps. It was found that both external mass transfer and intraparticle diffusion played an important role in the adsorption mechanisms of dye, and adsorption kinetics followed the pseudo-second-order type kinetic model. The thermodynamic analysis indicated that the sorption process was exothermic and spontaneous in nature.
Afficher plus [+] Moins [-]Chemical and biomarker responses for site-specific quality assessment of the Lake Maggiore (Northern Italy)
2013
Parolini, Marco | Pedriali, Alessandra | Binelli, Andrea
Since the 1990s, the Lake Maggiore (Northern Italy) has been recognized as an aquatic environment contaminated by DDTs and other persistent organic pollutants, but to date just few studies were carried out to investigate the effects of pollution to aquatic organisms. The aim of this study was the application of a stepwise approach based on chemical data, a suite of biomarkers and the integration of their responses into a biomarker response index (BRI) to evaluate the site-specific quality assessment in different sampling stations of Lake Maggiore, one of the largest European lakes. We used as biological model the freshwater bivalve Zebra mussel (Dreissena polymorpha). Several hundred bivalve specimens were sampled on May 2011 from eight sampling sites located along the lake shoreline. We measured levels of DDTs, PCBs, HCHs, HCB, and PAHs accumulated in D. polymorpha soft tissues by GC/MSn, while the activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione S-transferase, as well as the lipid peroxidation and protein carbonyl content were evaluated in homogenates from native bivalves as oxidative stress indices. Moreover, DNA damage was investigated by the alkaline precipitation assay. Significant imbalances of enzymatic activity were found in mussels from most of the sampling sites, as well as notable increases of damage to macromolecules. Health status of mussels from Baveno was greatly affected by lake pollution, probably due to high levels of DDTs measured in this site, while a wide variability in biomarker responses was found in all the other stations. The application of a BRI allowed distinguishing impacts of pollution to bivalves, confirming mussels from Baveno as the most threatened and revealing that also the health status of bivalves from Suna, Brissago, Pallanza, and Laveno is affected. These evidences suggest the usefulness of a specific index to integrate all the biomarker endpoints in order to provide a correct environmental risk assessment.
Afficher plus [+] Moins [-]Antioxidant response of soybean seedlings to joint stress of lanthanum and acid rain
2013
Liang, Chanjuan | Wang, Weimin
Excess of rare earth elements in soil can be a serious environmental stress on plants, in particular when acid rain coexists. To understand how such a stress affects plants, we studied antioxidant response of soybean leaves and roots exposed to lanthanum (0.06, 0.18, and 0.85 mmol L(-1)) under acid rain conditions (pH 4.5 and 3.0). We found that low concentration of La(3+) (0.06 mmol L(-1)) did not affect the activity of antioxidant enzymes (catalase and peroxidase) whereas high concentration of La(3+) (≥0.18 mmol L(-1)) did. Compared to treatment with acid rain (pH 4.5 and pH 3.0) or La(3+) alone, joint stress of La(3+) and acid rain affected more severely the activity of catalase and peroxidase, and induced more H2O2 accumulation and lipid peroxidation. When treated with high level of La(3+) (0.85 mmol L(-1)) alone or with acid rain (pH 4.5 and 3.0), roots were more affected than leaves regarding the inhibition of antioxidant enzymes, physiological function, and growth. The severity of oxidative damage and inhibition of growth caused by the joint stress associated positively with La(3+) concentration and soil acidity. These results will help us understand plant response to joint stress, recognize the adverse environmental impact of rare earth elements in acidic soil, and develop measures to eliminate damage caused by such joint stress.
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