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Resultados 1971-1980 de 2,492
A new device for formaldehyde and total aldehydes real-time monitoring
2014
Sassine, Maria | Picquet-Varrault, Bénédicte | Perraudin, Emilie | Chiappini, Laura | Doussin, Jean François | George, Christian
A new sensitive technique for the quantification of formaldehyde (HCHO) and total aldehydes has been developed in order to monitor these compounds, which are known to be involved in air quality issues and to have health impacts. Our approach is based on a colorimetric method where aldehydes are initially stripped from the air into a scrubbing solution by means of a turning coil sampler tube and then derivatised with 3-methylbenzothiazolinone-2-hydrazone in acid media (pH = −0.5). Hence, colourless aldehydes are transformed into blue dyes that are detected by UV–visible spectroscopy at 630 nm. Liquid core waveguide LCW Teflon® AF-2400 tube was used as innovative optical cells providing a HCHO detection limit of 4 pptv for 100 cm optical path with a time resolution of 15 min. This instrument showed good correlation with commonly used techniques for aldehydes analysis such as DNPH derivatisation chromatographic techniques with off-line and on-line samplers, and DOAS techniques (with deviation below 6 %) for both indoor and outdoor conditions. This instrument is associated with simplicity and low cost, which is a prerequisite for indoor monitoring.
Mostrar más [+] Menos [-]Altered physiology, cell structure, and gene expression of Theobroma cacao seedlings subjected to Cu toxicity
2014
Souza, Vânia L. | Almeida, Alex-Alan F. | de S. Souza, Jadiel | Mangabeira, Pedro A. O. | de Jesus, Raildo M. | Pirovani, Carlos P. | Ahnert, Dário | Baligar, V. C. | Loguercio, Leandro L.
Seedlings of Theobroma cacao CCN 51 genotype were grown under greenhouse conditions and exposed to increasing concentrations of Cu (0.005, 1, 2, 4, 8, 16, and 32 mg Cu L−1) in nutrient solution. When doses were equal or higher than 8mg Cu L−1, after 24 h of treatment application, leaf gas exchange was highly affected and changes in chloroplasts thylakoids of leaf mesophyll cells and plasmolysis of cells from the root cortical region were observed. In addition, cell membranes of roots and leaves were damaged. In leaves, 96 h after treatments started, increases in the percentage of electrolyte leakage through membranes were observed with increases of Cu in the nutrient solution. Moreover, there was an increase in the concentration of thiobarbituric acid-reactive substances in roots due to lipid peroxidation of membranes. Chemical analysis showed that increases in Cu concentrations in vegetative organs of T. cacao increased with the increase of the metal in the nutrient solution, but there was a greater accumulation of Cu in roots than in shoots. The excess of Cu interfered in the levels of Mn, Zn, Fe, Mg, K, and Ca in different organs of T. cacao. Analysis of gene expression via RTq-PCR showed increased levels of MT2b, SODCyt, and PER-1 expression in roots and of MT2b, PSBA, PSBO, SODCyt, and SODChI in leaves. Hence, it was concluded that Cu in nutrient solution at doses equal or above 8 mg L−1 significantly affected leaf gas exchange, cell ultrastructure, and transport of mineral nutrients in seedlings of this T. cacao genotype.
Mostrar más [+] Menos [-]Site-specific water quality guidelines: 2. Development of a water quality regulation framework for pulse exposures of mine water discharges at a uranium mine in northern Australia
2014
Sinclair, A. | Tayler, K. | van Dam, R. | Hogan, A.
The Ranger Uranium Mine, in northern Australia, is monitored by the Supervising Scientist Division (SSD) of the Australian Government to ensure that it does not impact on the highly valued aquatic ecosystems of Kakadu National Park. In 2010, the SSD adopted the continuous monitoring of electrical conductivity (EC) and turbidity, in combination with event-triggered automated grab samples, as its primary water quality monitoring method. The continuous monitoring of EC has shown that mine discharges typically occur over short-term ‘pulse’ durations of minutes to hours. Given that magnesium (Mg) is the most likely mine-derived solute to approach or exceed the applicable water quality limit value, the focus has been on developing a pulse exposure assessment framework for Mg, as represented by its proxy EC, which is tracked by the continuous monitoring system. This study presents a possible ecotoxicologically derived Mg pulse exposure limit and trigger regulation framework for Magela and Gulungul Creeks and an assessment of historic continuous monitoring EC data from these creeks. This framework demonstrates potential to supersede the current EC guideline and associated trigger levels, which are statistically derived from historic grab sample data.
Mostrar más [+] Menos [-]Climate change and air pollution jointly creating nightmare for tourism industry
2014
Sajjad, Faiza | Noreen, Umara | Zaman, Khalid
The objective of the study is to examine the long-run and causal relationship between climate change (i.e., greenhouse gas emissions, hydrofluorocarbons, per fluorocarbons, and sulfur hexafluoride), air pollution (i.e., methane emissions, nitrous oxide emissions, and carbon dioxide emissions), and tourism development indicators (i.e., international tourism receipts, international tourism expenditures, natural resource depletion, and net forest depletion) in the World’s largest regions. The aggregate data is used for robust analysis in the South Asia, the Middle East and North Africa, sub-Saharan Africa, and East Asia and the Pacific regions, over a period of 1975–2012. The results show that climatic factors and air pollution have a negative impact on tourism indicators in the form of deforestation and natural resource depletion. The impact is evident, as we have seen the systematic eroding of tourism industry, due to severe changes in climate and increasing strain of air pollution. There are several channels of cause–effect relationship between the climatic factors, air pollution, and tourism indicators in the World’s region. The study confirms the unidirectional, bidirectional, and causality independent relationship between climatic factors, air pollution, and tourism indicators in the World. It is conclusive that tourism industry is facing all time bigger challenges of reduce investment, less resources, and minor importance from the government agencies because of the two broad challenges, i.e., climate change and air pollution, putting them in a dismal state.
Mostrar más [+] Menos [-]Evaluation of heavy metal and polycyclic aromatic hydrocarbons accumulation in plants from typical industrial sites: potential candidate in phytoremediation for co-contamination
2014
Sun, Lu | Liao, Xiaoyong | Yan, Xiulan | Zhu, Ganghui | Ma, Dong
The heavy metal and polycyclic aromatic hydrocarbons (PAHs) contents were evaluated in surface soil and plant samples of 18 wild species collected from 3 typical industrial sites in South Central China. The accumulative characteristics of the plant species for both heavy metal and PAHs were discussed. The simultaneous accumulation of heavy metal and PAHs in plant and soil was observed at all the investigated sites, although disparities in spatial distributions among sites occurred. Both plant and soil samples were characterized by high accumulation for heavy metal at smelting site, moderate enrichment at coke power and coal mining sites, whereas high level of PAHs (16 priority pollutants according to US Environmental Protection Agency) at coke power site, followed sequentially by coal mining and smelting sites. Based on the differences of heavy metal and PAH accumulation behaviors of the studied plant species, heavy metal and PAH accumulation strategies were suggested: Pteris vittata L. and Pteris cretica L. for As and PAHs, Boehmeria nivea (L.) Gaud for Pb, As, and PAHs, and Miscanthus floridulu (Labnll.) Warb for Cu and PAHs. These native plant species could be proposed as promising materials for heavy metal and PAHs combined pollution remediation.
Mostrar más [+] Menos [-]Association of serum lead and mercury level with cardiometabolic risk factors and liver enzymes in a nationally representative sample of adolescents: the CASPIAN-III study
2014
Poursafa, Parinaz | Ataee, Ehsan | Motlagh, Mohammad Esmaeel | Ardalan, Gelayol | Tajadini, Mohammad Hassan | Yazdi, Maryam | Kelishadi, Roya
This study aims to determine the difference of serum Pb and Hg levels in adolescents with or without metabolic syndrome (MetS) and the association of serum levels of these heavy metals with cardiometabolic risk factors and liver enzymes in Iranian adolescents. The study population consisted of 320 adolescents (160 with MetS and 160 healthy controls). The relationship between serum heavy metals and cardiometabolic risk factors was assessed by linear regression. The odds ratios (OR) of having metabolic syndrome across Pb and Hg quartiles were determined by multiple logistic regression analysis. The mean (SD) of Pb and Hg concentrations were higher in adolescents with MetS than in those without it (0.83 (0.27) and 0.17 (0.01) vs. 0.65 (0.15) and 0.10 (0.08) μg/L, P = 0.01 and 0.0001, respectively). Increase in serum Pb and Hg was associated with increase in some cardiometabolic risk factors. Among boys and girls, diastolic blood pressure (DBP), fasting blood glucose, total cholesterol (TC), triglycerides (TG), and alanine aminotransaminase increased significantly across quartiles of serum Pb. Among girls, SBP, DBP, TC, and TG had a significant increase across Hg quartiles. The corresponding figure among boys was significant for SBP, DBP, and TG. Higher quartiles of Pb increased the risk of having MetS (OR 95 % CI 3.10, 2.25–4.27), the corresponding figure was 2.03, 1.75–3.16, across Hg quartiles. Our study showed significant associations between serum Pb and Hg levels with cardiometabolic risk factors in adolescents. In future surveys, the role of potential confounders should be considered more extensively. The clinical significance of these findings needs to be confirmed in longitudinal studies. By considering the origins of chronic diseases from early life, controlling environmental pollutants should be considered as a health priority for primordial or primary prevention of noncommunicable diseases.
Mostrar más [+] Menos [-]Removal of non-steroidal anti-inflammatory drugs ibuprofen and ketoprofen from water by emulsion liquid membrane
2014
Dâas, Attef | Hamdaoui, Oualid
In this work, the removal of the worldwide non-steroidal anti-inflammatory drugs ibuprofen (IBP) and ketoprofen (KTP) by emulsion liquid membrane (ELM) was carried out. An ELM system is made up of hexane as diluent, Span 80 as the surfactant and sodium carbonate as the inner aqueous solution. Effect of experimental conditions that affect the extraction of IBP such as surfactant concentration, emulsification time, sulfuric acid concentration in external phase, acid type in external phase, internal phase concentration, type of internal phase, stirring speed, volume ratio of internal phase to membrane phase, treatment ratio, IBP initial concentration, diluent type and salt was investigated. The obtained results showed that by appropriate selection of the operational parameters, it was possible to extract nearly all of IBP molecules from the feed solution even in the presence of high concentration of salt. Under optimum operating conditions, the efficiencies of IBP removal from distilled water (99.3 %), natural mineral water (97.3 %) and sea water (94.0 %) were comparable, which shows that the ELM treatment process represents a very interesting advanced separation process for the removal of IBP from complex matrices such as natural and sea waters. Under the optimized experimental conditions, approximately 97.4 % KTP was removed in less than 20 min of contact time.
Mostrar más [+] Menos [-]Statistical thermodynamics of adsorption of dye DR75 onto natural materials and its modifications: double-layer model with two adsorption energies
2014
Khalfaoui, M. | Nakhli, A. | Aguir, Ch | Omri, A. | M’henni, M. F. | Ben Lamine, A.
In this article, adsorption modelling was presented to describe the sorption of textile dye, Direct Red 75 (DR75), from coloured wastewater onto the natural and modified adsorbent, Posidonia oceanica. The formulation of the double-layer model with two energy levels was based on statistical physics and theoretical considerations. Thanks to the grand canonical ensemble in statistical physics some physico-chemical parameters related to the adsorption process were introduced in the analytical model expression. Fitting results show that the dye molecules are adsorbed in parallel position to the adsorbent surface. The magnitudes of the calculated adsorption energies show that the DR75 dye is physisorbed onto Posidonia. Both Van der Waals and hydrogen interactions are implicated in the adsorption process. Despite its simplicity, the model fits a wide range of experimental data, thereby supporting the underlying data that the grafted groups facilitate the parallel anchorage of the anionic dye molecule. Thermodynamic parameters, such as adsorption energy, entropy, Gibbs free adsorption energy and internal energy were calculated according to the double-layer model. Results suggested that the DR75 adsorption onto Posidonia was a spontaneous and exothermic process.
Mostrar más [+] Menos [-]TXRF analysis of soils and sediments to assess environmental contamination
2014
Bilo, Fabjola | Borgese, Laura | Cazzago, Davide | Zacco, Annalisa | Bontempi, Elza | Guarneri, Rita | Bernardello, Marco | Attuati, Silvia | Lazo, Pranvera | Depero, Laura E.
Total reflection x-ray fluorescence spectroscopy (TXRF) is proposed for the elemental chemical analysis of crustal environmental samples, such as sediments and soils. A comparative study of TXRF with respect to flame atomic absorption spectroscopy and inductively coupled plasma optical emission spectroscopy was performed. Microwave acid digestion and suspension preparation methods are evaluated. A good agreement was found among the results obtained with different spectroscopic techniques and sample preparation methods for Cr, Mn, Fe, Ni, Cu, and Zn. We demonstrated that TXRF is suitable for the assessment of environmental contamination phenomena, even if the errors for Pb, As, V, and Ba are ingent.
Mostrar más [+] Menos [-]Phosphorus and cadmium interactions in Kandelia obovata (S. L.) in relation to cadmium tolerance
2014
Du, Jingna | Yan, Chongling | Li, Zhaodeng
This study focused on the cadmium (Cd) tolerance of mangroves with application of phosphate (P) in order to explore whether exogenous P can alleviate Cd stress on these intertidal species. Kandelia obovata (S. L.) seedlings were cultivated in rhizoboxes under different levels of Cd and P concentrations. The speciation distributions of Cd in the rhizosphere and non-rhizosphere sediments were examined by sequential extraction procedures; organic acid in plant tissues and soil solution was measured by high-performance liquid chromatography; Cd and P accumulation in the plants was also determined. Results showed that considerable differences existed in Cd speciation distributions between rhizosphere and non-rhizosphere sediments. Root activity influenced the dynamics of Cd, P application increased the organic acid content in root tissues, P also increased Cd accumulation in roots whilst lowering Cd translocation from root to the above-ground tissues, and a significant positive correlation was found between Cd and P in roots (r = 0.905). It is postulated that Cd detoxification of K. obovata (S. L.) is associated with higher Cd immobilization in the presence of higher P and organic acid contents in root tissue.
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