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Aqueous suspensions of carbon nanotubes: Surface oxidation, colloidal stability and uranium sorption [Erratum: 2009 Oct., v. 157, no. 10, p. 2891.] Texte intégral
2009
Schierz, A. | Zänker, H.
The objective of this study is to obtain information on the behaviour of carbon nanotubes (CNTs) as potential carriers of pollutants in the case of accidental CNT release to the environment and on the properties of CNTs as a potential adsorbent material in water purification. The effects of acid treatment of CNTs on (i) the surface properties, (ii) the colloidal stability and (iii) heavy metal sorption are investigated, the latter being exemplified by uranium(VI) sorption. There is a pronounced influence of surface treatment on the behaviour of the CNTs in aqueous suspension. Results showed that acid treatment increases the amount of acidic surface groups on the CNTs. Therefore, acid treatment has an increasing effect on the colloidal stability of the CNTs and on their adsorption capacity for U(VI). Another way to stabilise colloids of pristine CNTs in aqueous suspension is the addition of humic acid. Acid treatment of carbon nanotubes has an increasing effect on their colloidal stability and on their adsorption capacity for U(VI).
Afficher plus [+] Moins [-]Sorption mechanisms of cephapirin, a veterinary antibiotic, onto quartz and feldspar minerals as detected by Raman spectroscopy Texte intégral
2009
Peterson, Jonathan W. | Seymour, Michael D. | Wang, Wei | Gu, Baohua
Raman spectroscopy was used to investigate sorption mechanisms of cephapirin (CHP), a veterinary antibiotic, onto quartz (SiO₂) and feldspar (KAlSi₃O₈) at different pH. Sorption occurs by electrostatic attraction, monodentate and bidentate complexation. The zwitterion (CHP⁰) adsorbs to a quartz(+) surface by electrostatic attraction of the carboxylate anion group (-COO-) at low pH, but adsorbs to a quartz(-) surface through electrostatic attraction of the pyridinium cation, and possibly COO- bridge complexes, at higher pH. CHP- bonds to quartz(-) surfaces by bidentate complexation between one oxygen of -COO- and oxygen from carbonyl of an acetoxymethyl group. On a feldspar(+/-) surface, CHP⁰ forms monodentate complexes between CO, and possible -COO- bridges and/or electrostatic attachments to localized edge (hydr)oxy-Al surfaces. CHP- adsorbs to feldspar(-) through monodentate CO complexation. Similar mechanisms may operate for other cephalosporins. Results demonstrate, for the first time, that Raman techniques can be effective for evaluating sorption mechanisms of antibiotics. Raman spectroscopy indicates that cephapirin, a veterinary antibiotic, sorbs to quartz and feldspar by electrostatic attraction, and monodentate and bidentate complexation.
Afficher plus [+] Moins [-]Sandhopper solar orientation as a behavioural biomarker of trace metals contamination Texte intégral
2009
Ungherese, Giuseppe | Ugolini, Alberto
Although many studies have focused on trace metals accumulation, investigations of talitrid amphipods as biomarkers are rare. This study explores the possibility of using the solar orientation capacity of Talitrus saltator as a behavioural marker of exposure to two essential (Cu and Zn) and two non-essential (Cd and Hg) metals. LC50 analyses performed before the solar orientation tests showed that the 72 h LC50 for Hg was 0.02 ppm while the 96 h LC50 values for Cu, Cd and Zn were 13.28 ppm, 27.66 ppm, and 62.74 ppm, respectively. The presence of metals in seawater affects the solar orientation capacity of T. saltator in a concentration-dependent manner and according to the toxicity ranking of the metals (Hg > Cu > Cd > Zn). Therefore, the solar orientation capacity of T. saltator seems to be a promising behavioural marker for exposure to trace metals. Solar orientation capacity is a promising behavioural marker for exposure to trace metals in sandhoppers.
Afficher plus [+] Moins [-]Adsorption and transformation of selected human-used macrolide antibacterial agents with iron(III) and manganese(IV) oxides Texte intégral
2009
Feitosa-Felizzola, Juliana | Hanna, Khalil | Chiron, Serge
The adsorption/transformation of two members (clarithromycin and roxithromycin) of the macrolide (ML) antibacterial agents on the surface of three environmental subsurface sorbents (clay, iron(III) and manganese(IV) oxy-hydroxides) was investigated. The adsorption fitted well to the Freundlich model with a high sorption capacity. Adsorption probably occurred through a surface complexation mechanism and was accompanied by slow degradation of the selected MLs. Transformation proceeded through two parallel pathways: a major pathway was the hydrolysis of the cladinose sugar, and to a lesser extent the hydrolysis of the lactone ring. A minor pathway was the N-dealkylation of the amino sugar. This study indicates that Fe(III) and Mn(IV) oxy-hydroxides in aquatic sediments may play an important role in the natural attenuation of MLs. Such an attenuation route yields a range of intermediates that might retain some of their biological activity. Iron(III) and manganese(IV) oxy-hydroxides in aquatic sediments may play an important role in the natural attenuation of macrolide antibacterial agents.
Afficher plus [+] Moins [-]Production and sedimentation of peptide toxins nodularin-R and microcystin-LR in the northern Baltic Sea Texte intégral
2009
Kankaanpää, Harri T. | Sjövall, Olli | Huttunen, Maija | Olin, Miikka | Karlsson, Krister | Hyvärinen, Kirsi | Sneitz, Laura | Härkönen, Janne | Sipiä, Vesa O. | Meriluoto, Jussi A.O.
This seven-year survey was primarily targeted to quantification of production of nodularin-R (NOD-R), a cyclic pentapeptide hepatotoxin, in Baltic Sea cyanobacteria waterblooms. Additionally, NOD-R and microcystin-LR (MC-LR; a cyclic heptapeptide toxin) sedimentation rates and NOD-R sediment storage were estimated. NOD-R production (70-2450 μg m⁻³; 1 kg km⁻² per season) and sedimentation rates (particles; 0.03-5.7 μg m⁻² d⁻¹; 0.3 kg km⁻² per season) were highly variable over space and time. Cell numbers of Nodularia spumigena did not correlate with NOD-R quantities. Dissolved NOD-R comprised 57-100% of total NOD-R in the predominantly senescent, low-intensity phytoplankton blooms and seston. Unprecedentedly intensive MC-LR sedimentation (0.56 μg m⁻² d⁻¹) occurred in 2004. Hepatotoxin sedimentation rates highly exceeded those of anthropogenic xenobiotics. NOD-R storage in surficial sediments was 0.4-20 μg kg⁻¹ (0.1 kg km⁻²). Loss of NOD-R within the chain consisting of phytoplankton, seston and soft sediments seemed very effective. Production of nodularin-R in pelagic Baltic Sea takes place in a scale of up to kilograms per square kilometre.
Afficher plus [+] Moins [-]Molecular characterization of copper in soils using X-ray absorption spectroscopy Texte intégral
2009
Strawn, Daniel G. | Baker, Leslie L.
Bioavailability of Cu in the soil is a function of its speciation. In this paper we investigated Cu speciation in six soils using X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and synchrotron-based micro X-ray fluorescence (μ-XRF). The XANES and EXAFS spectra in all of the soils were the same. μ-XRF results indicated that the majority of the Cu particles in the soils were not associated with calcium carbonates, Fe oxides, or Cu sulfates. Principal component analysis and target transform of the XANES and EXAFS spectra suggested that Cu adsorbed on humic acid (HA) was an acceptable match. Thus it appears that Cu in all of the soils is primarily associated with soil organic matter (SOM). Theoretical fitting of the molecular structure in the soil EXAFS spectra revealed that the Cu in the soils existed as Cu atoms bound in a bidentate complex to O or N functional groups.
Afficher plus [+] Moins [-]Characterization of aluminium-based water treatment residual for potential phosphorus removal in engineered wetlands Texte intégral
2009
Babatunde, A.O. | Zhao, Y.Q. | Burke, A.M. | Morris, M.A. | Hanrahan, J.P.
Aluminium-based water treatment residual (Al-WTR) is the most widely generated residual from water treatment facilities worldwide. It is regarded as a by-product of no reuse potential and landfilled. This study assessed Al-WTR as potential phosphate-removing substrate in engineered wetlands. Results indicate specific surface area ranged from 28.0 m² g⁻¹ to 41.4 m² g⁻¹. X-ray Diffraction, Fourier transform infrared and energy-dispersive X-ray spectroscopes all indicate Al-WTR is mainly composed of amorphous aluminium which influences its phosphorus (P) adsorption capacity. The pH and electrical conductivity ranged from 5.9 to 6.0 and 0.104 dS m⁻¹ to 0.140 dS m⁻¹ respectively, showing that it should support plant growth. Batch tests showed adsorption maxima of 31.9 mg P g⁻¹ and significant P removal was achieved in column tests. Overall, results showed that Al-WTR can be used for P removal in engineered wetlands and it carries the benefits of reuse of a by-product that promotes sustainability.
Afficher plus [+] Moins [-]Widespread waterborne pollution in central Swedish lakes and the Baltic Sea from pre-industrial mining and metallurgy Texte intégral
2009
Bindler, Richard | Renberg, Ingemar | Rydberg, Johan | Andrén, Thomas
Metal pollution is viewed as a modern problem that began in the 19th century and accelerated through the 20th century; however, in many parts of the globe this view is wrong. Here, we studied past waterborne metal pollution in lake sediments from the Bergslagen region in central Sweden, one of many historically important mining regions in Europe. With a focus on lead (including isotopes), we trace mining impacts from a local scale, through a 120-km-long river system draining into Mälaren - Sweden's third largest lake, and finally also the Baltic Sea. Comparison of sediment and peat records shows that pollution from Swedish mining was largely waterborne and that atmospheric deposition was dominated by long-range transport from other regions. Swedish ore lead is detectable from the 10th century, but the greatest impact occurred during the 16th-18th centuries with improvements occurring over recent centuries, i.e., historical pollution > modern industrial pollution. Pollution in Sweden during AD 900-1900 was often greater than modern industrial pollution.
Afficher plus [+] Moins [-]Interacting effects of sulphate pollution, sulphide toxicity and eutrophication on vegetation development in fens: A mesocosm experiment Texte intégral
2009
Geurts, Jeroen J.M. | Sarneel, Judith M. | Willers, Bart J.C. | Roelofs, Jan G.M. | Verhoeven, Jos T.A. | Lamers, Leon P.M.
Both eutrophication and SO₄ pollution can lead to higher availability of nutrients and potentially toxic compounds in wetlands. To unravel the interaction between the level of eutrophication and toxicity at species and community level, effects of SO₄ were tested in nutrient-poor and nutrient-rich fen mesocosms. Biomass production of aquatic and semi-aquatic macrophytes and colonization of the water layer increased after fertilization, leading to dominance of highly competitive species. SO₄ addition increased alkalinity and sulphide concentrations, leading to decomposition and additional eutrophication. SO₄ pollution and concomitant sulphide production considerably reduced biomass production and colonization, but macrophytes were less vulnerable in fertilized conditions. The experiment shows that competition between species, vegetation succession and terrestrialization are not only influenced by nutrient availability, but also by toxicity, which strongly interacts with the level of eutrophication. This implies that previously neutralized toxicity effects in eutrophied fens may appear after nutrient reduction measures have been taken. Interspecific competition, vegetation succession and terrestrialization in fens depend on the interacting effects of SO₄ pollution, sulphide toxicity and nutrient availability.
Afficher plus [+] Moins [-]Correlations between dioxin-like and indicators PCBs: Potential consequences for environmental studies involving fish or sediment Texte intégral
2009
Babut, M. | Miege, C. | Villeneuve, B. | Abarnou, A. | Duchemin, J. | Marchand, P. | Narbonne, J.F.
Correlations between dioxin-like and indicators PCBs: Potential consequences for environmental studies involving fish or sediment Texte intégral
2009
Babut, M. | Miege, C. | Villeneuve, B. | Abarnou, A. | Duchemin, J. | Marchand, P. | Narbonne, J.F.
Among the numerous PCB congeners, most of the dioxin-like PCBs (DL-PCBs) need to be characterized by hyphenated techniques. It has been shown in several instances that these congeners are well related to the total PCB content in fish. We examined datasets collected mainly in France, on freshwater and marine fish and sediments. A statistical model linking DL- and indicator PCBs was developed for a dataset composed of freshwater fishes, and proved to predict well DL-PCBs from indicator PCBs in all other fish sets, including marine ones. Type II error rates remained low in almost all fish sets. A similar correlation was observed in sediments. Non-dioxin-like PCBs elicit various adverse effects and represent 95% of the total PCBs. A European guideline for them is needed; the correlation between DL- and indicator PCBs could help develop this standard in the future. Dioxin-like PCBs in fish and maybe sediments are rather well predicted by indicator PCBs.
Afficher plus [+] Moins [-]Correlations between dioxin-like and indicators PCBs: Potential consequences for environmental studies involving fish or sediment Texte intégral
2009
Babut, M. | Miege, C. | Villeneuve, B. | Abarnou, Alain | Duchemin, J. | Marchand, P. | Narbonne, J. F.
Among the numerous PCB congeners, most of the dioxin-like PCBs (DL-PCBs) need to be characterized by hyphenated techniques. It has been shown in several instances that these congeners are well related to the total PCB content in fish. We examined datasets collected mainly in France, on freshwater and marine fish and sediments. A statistical model linking DL- and indicator PCBs was developed for a dataset composed of freshwater fishes, and proved to predict well DL-PCBs from indicator PCBs in all other fish sets, including marine ones. Type II error rates remained low in almost all fish sets. A similar correlation was observed in sediments. Non-dioxin-like PCBs elicit various adverse effects and represent 95% of the total PCBs. A European guideline for them is needed; the correlation between DL- and indicator PCBs could help develop this standard in the future. (C) 2009 Elsevier Ltd. All rights reserved.
Afficher plus [+] Moins [-]Correlations between dioxin-like and indicators PCBs: Potential consequences for environmental studies involving fish or sediment Texte intégral
2009
Babut, M. | Miege, Cecile | Villeneuve, B. | Abarnou, A. | Duchemin, J. | Marchand, P. | Narbonne, J.F. | Biologie des écosystèmes aquatiques (UR BELY) ; Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF) | Qualité des eaux et prévention des pollutions (UR QELY) ; Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF) | Physiologie Fonctionnelle des Organismes Marins (PFOM) ; Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) | Agence de l'Eau Seine-Normandie | École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique (ONIRIS) | Laboratoire de Physico -& Toxico Chimie des systèmes naturels (LPTC) ; Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS)
[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA | Among the numerous PCB congeners, most of the dioxin-like PCBs (DL-PCBs) need to be characterized by hyphenated techniques. It has been shown in several instances that these congeners are well related to the total PCB content in fish.We examined datasets collected mainly in France, on freshwater and marine fish and sediments. A statistical model linking DL- and indicator PCBs was developed for a dataset composed of freshwater fishes, and proved to predict well DL-PCBs from indicator PCBs in all other fish sets, including marine ones. Type II error rates remained low in almost all fish sets. A similar correlation was observed in sediments. Non-dioxin-like PCBs elicit various adverse effects and represent 95% of the total PCBs. A European guideline for them is needed; the correlation between DL- and indicator PCBs could help develop this standard in the future.
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