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Результаты 2131-2140 из 2,512
Immobilised Phaeodactylum tricornutum as biomonitor of trace element availability in the water column during dredging Полный текст
2014
Cabrita, Maria Teresa | Raimundo, Joana | Pereira, Patrícia | Vale, Carlos
Immobilised Phaeodactylum tricornutum as biomonitor of trace element availability in the water column during dredging Полный текст
2014
Cabrita, Maria Teresa | Raimundo, Joana | Pereira, Patrícia | Vale, Carlos
This work reports changes of Cr, Cu, Zn, Cd, Hg and Pb concentrations in the dissolved fraction, suspended particulate matter and immobilised Phaeodactylum tricornutum Bohlin (Bacillariophyceae), as well as of microalgae specific growth rates, during a 5-month period dredging operation in a contaminated area of the Tagus estuary, Portugal. Trace element concentrations showed broad variations in the dissolved fraction and suspended particulate matter, presumably reflecting rapid exchanges of redox-sensitive elements between water and particles, in conjunction with the dilution effect caused by the tidal excursion. Immobilised cells exposed to dredging environmental conditions showed significantly higher concentrations of Cr, Cu, Zn, Cd, Hg and Pb than under no dredging conditions. Concomitantly, specific cell growth was significantly lower, suggesting that elements released with dredging affect the microalgae physiology. The results obtained in this in situ work imply that the dissolved fraction and the suspended particulate matter are relatively ineffective indicators of the trace element enhancement during dredging and pointed out immobilised P. tricornutum as a reliable and efficient biomonitoring tool for the assessment of trace element remobilisation.
Показать больше [+] Меньше [-]Immobilised Phaeodactylum tricornutum as biomonitor of trace element availability in the water column during dredging Полный текст
2014 | 1000
Cabrita, Maria Teresa | Raimundo, Joana | Pereira, Patrícia | Vale, Carlos
This work reports changes of Cr, Cu, Zn, Cd, Hg and Pb concentrations in the dissolved fraction, suspended particulate matter and immobilised Phaeodactylum tricornutum Bohlin (Bacillariophyceae), as well as of microalgae specific growth rates, during a 5-month period dredging operation in a contaminated area of the Tagus estuary, Portugal. Trace element concentrations showed broad variations in the dissolved fraction and suspended particulate matter, presumably reflecting rapid exchanges of redox-sensitive elements between water and particles, in conjunction with the dilution effect caused by the tidal excursion. Immobilised cells exposed to dredging environmental conditions showed significantly higher concentrations of Cr, Cu, Zn, Cd, Hg and Pb than under no dredging conditions. Concomitantly, specific cell growth was significantly lower, suggesting that elements released with dredging affect the microalgae physiology. The results obtained in this in situ work imply that the dissolved fraction and the suspended particulate matter are relatively ineffective indicators of the trace element enhancement during dredging and pointed out immobilised P. tricornutum as a reliable and efficient biomonitoring tool for the assessment of trace element remobilisation.
Показать больше [+] Меньше [-]Framing environmental problems: Problem entrepreneurs and the issue of water pollution from agriculture in Brittany, 1970-2005 Полный текст
2014
Bourblanc M.
Framing environmental problems: Problem entrepreneurs and the issue of water pollution from agriculture in Brittany, 1970-2005 Полный текст
2014
Bourblanc M.
The claim that public problems are constructs is now widely recognized as justified and was first established in social problem theory. The high instability of problem definition activities in the case of water pollution coming from agriculture in Brittany demonstrates this particularly well. The objective of this article is to describe ways by which an environmental movement organization (EMO) conceives its activities of public problem construction. Inspired by social movement theory, but aiming at overcoming its weaknesses, the paper seeks to highlight the influence of EMO endogenous meaning production in problem construction processes, a dimension often overlooked even by framing theory. In a bid to support that claim, the paper shows the influence of the affective dimension over the strategic one within the problematization process. Forging a conceptual distinction characterized by a perceived problem and strategic definitions, the paper underlines the fundamental interrelated nature of these two components and consequently emphasizes the reciprocal dependence of the perceived problem over the strategic (either material or cognitive) definitions. Finally, the paper evokes the benefit and impact of this conceptual distinction on the policy-making process. (Résumé d'auteur)
Показать больше [+] Меньше [-]Framing Environmental Problems: Problem Entrepreneurs and the Issue of Water Pollution from Agriculture in Brittany, 1970–2005 Полный текст
2014
Bourblanc, Magalie
The claim that public problems are constructs is now widely recognized as justified and was first established in social problem theory. The high instability of problem definition activities in the case of water pollution coming from agriculture in Brittany demonstrates this particularly well. The objective of this article is to describe ways by which an environmental movement organization (EMO) conceives its activities of public problem construction. Inspired by social movement theory, but aiming at overcoming its weaknesses, the paper seeks to highlight the influence of EMO endogenous meaning production in problem construction processes, a dimension often overlooked even by framing theory. In a bid to support that claim, the paper shows the influence of the affective dimension over the strategic one within the problematization process. Forging a conceptual distinction characterized by a perceived problem and strategic definitions, the paper underlines the fundamental interrelated nature of these two components and consequently emphasizes the reciprocal dependence of the perceived problem over the strategic (either material or cognitive) definitions. Finally, the paper evokes the benefit and impact of this conceptual distinction on the policy-making process.
Показать больше [+] Меньше [-]Effects of chronic exposure to lead, copper, zinc, and cadmium on biomarkers of the European eel, Anguilla anguilla Полный текст
2014
Nunes, Bruno | Capela, Ricardo Campinho | Sérgio, Tânia | Caldeira, Carina | Gonçalves, Fernando | Correia, Alberto Teodorico
Effects of chronic exposure to lead, copper, zinc, and cadmium on biomarkers of the European eel, Anguilla anguilla Полный текст
2014
Nunes, Bruno | Capela, Ricardo Campinho | Sérgio, Tânia | Caldeira, Carina | Gonçalves, Fernando | Correia, Alberto Teodorico
Exposure to specific metallic compounds can cause severe deleterious modifications in organisms. Fishes are particularly prone to toxic effects from exposure to metallic compounds via their environment. Species that inhabit estuaries or freshwater environments can be chronically affected by persistent exposure to a large number of metallic compounds, particularly those released by industrial activities. In this study, we exposed yellow eels (European eel, Anguilla anguilla) for 28 days to environmentally relevant concentrations of four specific metals; lead (300, 600, and 1,200 μg/l), copper (40, 120, and 360 μg/l), zinc (30, 60, and 120 μg/l) and cadmium (50, 150, and 450 μg/l). The selected endpoints to assess the toxicological effects were neurotransmission (cholinesterasic activity in nervous tissue), antioxidant defense, and phase II metabolism (glutathione-S-transferase [GST] activity, in both gills and liver tissues), and peroxidative damage. The results showed an overall lack of effects on acetylcholinesterase for all tested metals. Lead, copper, and cadmium exposure caused a significant, dose-dependent, increase in GST activity in gill tissue. However, liver GST only significantly increased following zinc exposure. No statistically significant effects were observed for the thiobarbituric acid reactive substances assay, indicating the absence of peroxidative damage. These findings suggest that, despite the occurrence of an oxidative-based response after exposure to lead, copper, and cadmium, this had no consequence in terms of peroxidative membrane damage; furthermore, cholinergic neurotoxicity caused by lead, copper, and cadmium did not occur. The implications of these results are further discussed.
Показать больше [+] Меньше [-]Effects of chronic exposure to lead, copper, zinc, and cadmium on biomarkers of the European eel, Anguilla anguilla Полный текст
2014 | 1000
Nunes, Bruno | Capela, Ricardo Campinho | Sérgio, Tânia | Caldeira, Carina | Gonçalves, Fernando | Correia, Alberto Teodorico
Exposure to specific metallic compounds can cause severe deleterious modifications in organisms. Fishes are particularly prone to toxic effects from exposure to metallic compounds via their environment. Species that inhabit estuaries or freshwater environments can be chronically affected by persistent exposure to a large number of metallic compounds, particularly those released by industrial activities. In this study, we exposed yellow eels (European eel, Anguilla anguilla) for 28 days to environmentally relevant concentrations of four specific metals; lead (300, 600, and 1,200 μg/l), copper (40, 120, and 360 μg/l), zinc (30, 60, and 120 μg/l) and cadmium (50, 150, and 450 μg/l). The selected endpoints to assess the toxicological effects were neurotransmission (cholinesterasic activity in nervous tissue), antioxidant defense, and phase II metabolism (glutathione-S-transferase [GST] activity, in both gills and liver tissues), and peroxidative damage. The results showed an overall lack of effects on acetylcholinesterase for all tested metals. Lead, copper, and cadmium exposure caused a significant, dose-dependent, increase in GST activity in gill tissue. However, liver GST only significantly increased following zinc exposure. No statistically significant effects were observed for the thiobarbituric acid reactive substances assay, indicating the absence of peroxidative damage. These findings suggest that, despite the occurrence of an oxidative-based response after exposure to lead, copper, and cadmium, this had no consequence in terms of peroxidative membrane damage; furthermore, cholinergic neurotoxicity caused by lead, copper, and cadmium did not occur. The implications of these results are further discussed.
Показать больше [+] Меньше [-]Solar CPC pilot plant photocatalytic degradation of bisphenol A in waters and wastewaters using suspended and supported-TiO₂. Influence of photogenerated species Полный текст
2014
Saggioro, Enrico Mendes | Oliveira, Anabela Sousa | Pavesi, Thelma | Tototzintle, Margarita Jiménez | Maldonado, Manuel Ignacio | Correia, Fábio Verissimo | Moreira, Josino Costa
Photocatalytic degradation of bisphenol A (BPA) in waters and wastewaters in the presence of titanium dioxide (TiO₂) was performed under different conditions. Suspensions of the TiO₂ were used to compare the degradation efficiency of BPA (20 mg L⁻¹) in batch and compound parabolic collector (CPC) reactors. A TiO₂ catalyst supported on glass spheres was prepared (sol–gel method) and used in a CPC solar pilot plant for the photodegradation of BPA (100 μg L⁻¹). The influence of OH·, O₂ ·⁻, and h ⁺ on the BPA degradation were evaluated. The radicals OH· and O₂ ·⁻ were proved to be the main species involved on BPA photodegradation. Total organic carbon (TOC) and carboxylic acids were determined to evaluate the BPA mineralization during the photodegradation process. Some toxicological effects of BPA and its photoproducts on Eisenia andrei earthworms were evaluated. The results show that the optimal concentration of suspended TiO₂ to degrade BPA in batch or CPC reactors was 0.1 g L⁻¹. According to biological tests, the BPA LC₅₀ in 24 h for E. andrei was of 1.7 × 10⁻² mg cm⁻². The photocatalytic degradation of BPA mediated by TiO₂ supported on glass spheres suffered strong influence of the water matrix. On real municipal wastewater treatment plant (MWWTP) secondary effluent, 30 % of BPA remains in solution; nevertheless, the method has the enormous advantage since it eliminates the need of catalyst removal step, reducing the cost of treatment.
Показать больше [+] Меньше [-]Comparative study of adsorption of Pb(II) on native garlic peel and mercerized garlic peel Полный текст
2014
Liu, Wei | Liu, Yifeng | Tao, Yaqi | Yu, Youjie | Jiang, Hongmei | Lian, Hongzhen
A comparative study using native garlic peel and mercerized garlic peel as adsorbents for the removal of Pb²⁺has been proposed. Under the optimized pH, contact time, and adsorbent dosage, the adsorption capacity of garlic peel after mercerization was increased 2.1 times and up to 109.05 mg g⁻¹. The equilibrium sorption data for both garlic peels fitted well with Langmuir adsorption isotherm, and the adsorbent–adsorbate kinetics followed pseudo-second-order model. These both garlic peels were characterized by elemental analysis, Fourier transform infrared spectrometry (FT-IR), and scanning electron microscopy, and the results indicated that mercerized garlic peel offers more little pores acted as adsorption sites than native garlic peel and has lower polymerization and crystalline and more accessible functional hydroxyl groups, which resulted in higher adsorption capacity than native garlic peel. The FT-IR and X-ray photoelectron spectroscopy analyses of both garlic peels before and after loaded with Pb²⁺further illustrated that lead was adsorbed on the through chelation between Pb²⁺and O atom existed on the surface of garlic peels. These results described above showed that garlic peel after mercerization can be a more attractive adsorbent due to its faster sorption uptake and higher capacity.
Показать больше [+] Меньше [-]Source, distribution, and health risk assessment of polycyclic aromatic hydrocarbons in urban street dust from Tianjin, China Полный текст
2014
Yu, Binbin | Xie, Xiujie | Ma, Lena Q. | Kan, Haidong | Zhou, Qixing
To better assess and understand potential health risk of urban residents exposed to urban street dust, the total concentration, sources, and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in 87 urban street dust samples from Tianjin as a Chinese megacity that has undergone rapid urbanization were investigated. In the meantime, potential sources of PAHs were identified using the principal component analysis (PCA), and the risk of residents’ exposure to PAHs via urban street dust was calculated using the Incremental Lifetime Cancer Risk (ILCR) model. The results showed that the total PAHs (∑PAHs) in urban street dust from Tianjin ranged from 538 μg kg⁻¹to 34.3 mg kg⁻¹, averaging 7.99 mg kg⁻¹. According to PCA, the two to three- and four to six-ring PAHs contributed 10.3 and 89.7 % of ∑PAHs, respectively. The ratio of the sum of major combustion specific compounds (ΣCOMB) / ∑PAHs varied from 0.57 to 0.79, averaging 0.64. The ratio of Ant/(Ant + Phe) varied from 0.05 to 0.41, averaging 0.10; Fla/(Fla + Pyr) from 0.40 to 0.68, averaging 0.60; BaA/(BaA + Chry) from 0.29 to 0.51, averaging 0.38; and IcdP/(IcdP + BghiP) from 0.07 to 0.37, averaging 0.22. The biomass combustion, coal combustion, and traffic emission were the main sources of PAHs in urban street dust with the similar proportion. According to the ILCR model, the total cancer risk for children and adults was up to 2.55 × 10⁻⁵and 9.33 × 10⁻⁵, respectively.
Показать больше [+] Меньше [-]Evaluation of the reaction artifacts in an annular denuder-based sampler resulting from the heterogeneous ozonolysis of naphthalene Полный текст
2014
Goriaux, Mathieu | Pflieger, Maryline | Monod, Anne | Gligorovski, Sasho | Strekowski, Rafal S. | Wortham, Henri
The heterogeneous ozonolysis of naphthalene adsorbed on XAD-4 resin was studied using an annular denuder technique. The experiments involved depositing a known quantity of naphthalene on the XAD-4 resin and then measuring the quantity of the solid naphthalene that reacted away under a constant flow of gaseous ozone (0.064 to 4.9 ppm) for a defined amount of time. All experiments were performed at room temperature (26 to 30 °C) and atmospheric pressure. The kinetic rate coefficient for the ozonolysis reaction of naphthalene adsorbed on XAD-4 resin is reported to be (10.1 ± 0.4) × 10⁻¹⁹ cm³ molecule⁻¹ s⁻¹(error is 2σ, precision only). This value is five times greater than the currently recommended literature value for the homogeneous gas phase reaction of naphthalene with ozone. The obtained rate coefficient is used to evaluate reaction artifacts from field concentration measurements of naphthalene, acenaphthene, and phenanthrene. The observed uncertainties associated with field concentration measurements of naphthalene, acenaphthene, and phenanthrene are reported to be much higher than the uncertainties associated with the artifact reactions. Consequently, ozone reaction artifact appears to be negligible compared to the observed field measurement uncertainty results.
Показать больше [+] Меньше [-]Characterization of hydrocarbon-degrading and biosurfactant-producing Pseudomonas sp. P-1 strain as a potential tool for bioremediation of petroleum-contaminated soil Полный текст
2014
Pacwa-Płociniczak, Magdalena | Płaza, Grażyna Anna | Poliwoda, Anna | Piotrowska-Seget, Zofia
The Pseudomonas sp. P-1 strain, isolated from heavily petroleum hydrocarbon-contaminated soil, was investigated for its capability to degrade hydrocarbons and produce a biosurfactant. The strain degraded crude oil, fractions A5 and P3 of crude oil, and hexadecane (27, 39, 27 and 13 % of hydrocarbons added to culture medium were degraded, respectively) but had no ability to degrade phenanthrene. Additionally, the presence of gene-encoding enzymes responsible for the degradation of alkanes and naphthalene in the genome of the P-1 strain was reported. Positive results of blood agar and methylene blue agar tests, as well as the presence of gene rhl, involved in the biosynthesis of rhamnolipid, confirmed the ability of P-1 for synthesis of glycolipid biosurfactant.¹H and¹³C nuclear magnetic resonance, Fourier transform infrared spectrum and mass spectrum analyses indicated that the extracted biosurfactant was affiliated with rhamnolipid. The results of this study indicate that the P-1 and/or biosurfactant produced by this strain have the potential to be used in bioremediation of hydrocarbon-contaminated soils.
Показать больше [+] Меньше [-]Metals bioaccumulation and histopathological biomarkers in Carcinus maenas crab from Bizerta lagoon, Tunisia Полный текст
2014
Ben-Khedher, Sana | Jebali, Jamel | Houas, Zohra | Nawéli, Hmida | Jrad, Amel | Banni, Mohamed | Boussetta, Hamadi
Metals concentrations and histolopathological lesions of gills and digestive gland were investigated in Carcinus maenas crabs sampled from Bizerta Lagoon and Kuriat Island (Tunisia) as control site. The concentrations of trace metals varied between tissues, sites and sampling time. The highest levels of the analysed metals in gills and digestive gland were noted in Menzel Bourguiba and Cimentery sites at both sampling times (February and July). The higher metals loads were associated with severe and various tissues alterations in contaminated crabs. We particularly noted in the gills a haemocytic infiltration, distension and enlargement of the lamellae, lifting of lamellar epithelium, necrotic lesions and fusion of lamellae in the most polluted sites (Menzel Bourguiba and Cimentery). Moreover, others pathological alterations were observed in digestive gland of crabs collected from polluted sites and with a severity site dependent. We observed necrotic tubules containing tissue debris in the lumen with more intensity in crabs collected from Cimentery site in both sampling times. The thickened basal laminae and the walling off of the tubules by haemocytes around the thickened basal laminae were more abundant at Menzel Bourguiba than at others sites. The coagulation in the thickened basal laminae was observed only at Cimentery in February. Tissues histopathological lesions were sensitive to discriminate crabs of different sites and demonstrated its usefulness in this biomonitoring study. We recommend the association of histopatholocial lesions to biochemical biomarkers in future biomonitoring studies.
Показать больше [+] Меньше [-]Day–night differences and seasonal variations of chemical species in PM10 over Xi’an, northwest China Полный текст
2014
Shen, Zhenxing | Cao, Junji | Zhang, Leiming | Liu, Li | Zhang, Qian | Li, Jianjun | Han, Yuemei | Zhu, Chongshu | Zhao, Zhuzi | Liu, Suixin
To investigate day–night differences and seasonal variations of PM₁₀and its chemical composition in an urban environment in Xi’an, northwest China, day- and nighttime PM₁₀mass and its chemical components including water-soluble ions (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, F⁻, Cl⁻, NO₃⁻, and SO₄²⁻), organic carbon (OC), elemental carbon, and water-soluble organic carbon (WSOC) were measured on selected representative days from 20 December 2006 to 12 November 2007. Annual mean PM₁₀concentration in this city was five times of the China Ambient Air Quality Standard for annual average (70 μg m⁻³). Carbonaceous fractions and water-soluble ions accounted for nearly one third and 12.4 %, respectively, of the annual mean PM₁₀mass. No dramatic day–night differences were found in the loadings of PM₁₀or its chemical components. Spring samples were highlighted by abundance of Ca²⁺, while the secondary aerosol species (SO₄²⁻, NO₃⁻, and NH₄⁺) and OC dominated in summer, autumn, and winter samples. Relatively low NO₃⁻/SO₄²⁻ratio suggested that stationary source emissions were more important than vehicle emissions in the source areas in this city. Strong relationships between WSOC and biomass markers (water-soluble K⁺, OC1, and OP) were observed in winter and autumn, indicating that WSOC was derived mainly from biomass burning in these seasons. This was also supported by analysis results on the biomass burning events. In contrast, poor correlations between WSOC and biomass markers were demonstrated in summer and spring, implying that WSOC was mainly formed as secondary organic carbon through photochemical activities.
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