Adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions bioremediation from aqueous solution using unmodified and EDTA-modified maize cob

The need to clean-up heavy metal contaminated environment can not be over emphasized. This paper describes the adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions from aqueous solution using unmodified and EDTA-modified maize cob. Maize cob was found to be an excellent adsorbent for the removal of these metal ions. The amount of metal ions adsorbed increased as the initial concentration increased. Also, EDTA - modification enhanced the adsorption capacity of maize cob probably due to the chelating ability of EDTA. Among the three adsorption isotherm tested, Dubinin-Radushkevich gave the best fit with R² value ranging from 0.9539 to 0.9973 and an average value of 0.9819. This is followed by Freundlich isotherm (Ave. 0.9783) and then the Langmuir isotherm (Ave. 0.7637). The sorption process was found to be a physiosorption process as seen from the apparent energy of adsorption which ranged from 2.05KJ\mol to 4.56KJ\mol. Therefore, this study demonstrates that maize cob which is an environmental pollutant could be used to adsorb heavy metals and achieve cleanliness thereby abating environmental nuisance caused by the maize cob.

Use of modified silica gel for concentrating Pb (II) and Cd (II) occurring in form of complex anions

The performance of silica gel, modified by the impregnation with a high molecular weight quaternary amine (triethyl octadecyl ammonium iodide), used for the concentration of heavy metals occurring in water is studied. The material under study captures Cd, Pb, which are capable of forming stable complexes with I- ions.The results obtained about the metal capture, under dynamic conditions, are described and metal ions are removed by desorption with EDTA and quantified by AAS.

Pohjakuonan käsittelyn ja hyötykäytön toimintamallin muodostaminen Kotkan Energia Oy:n jätteenpolttolaitokselle

Tavoitteena tässä diplomityössä oli selvittää Kotkan Energia Oy:n jätteenpolttolaitoksen toiminnassa syntyvän pohjakuonan hyötykäyttömahdollisuuksia ja kustannuksiltaan järkevin tapa käsitellä pohjakuona. Tarkasteltavia vaihtoehtoja hyötykäytön osalta olivat erilaiset maarakennustyöt sekä kaatopaikkojen peittäminen. Hyötykäyttövaihtoehdoille vaihtoehtoisena ratkaisuna tutkittiin kaatopaikkasijoituksen kannattavuutta. Pohjakuonan käyttöä maarakentamisessa, jätetäyttöjen peitemaina sekä pohjakuonan loppusijoitusta kaatopaikoille säätelee lainsäädäntö. Valtioneuvoston asetuksessa kaatopaikoista on määritelty loppusijoitettaville jakeille liukoisuus raja-arvot, joiden mukaisesti jätteet sijoitetaan joko pysyvän jätteen, tavanomaisen jätteen tai ongelmajätteen kaatopaikoille. Jätetäyttöjen peitemateriaalina käytettävän jakeen on myös täytettävä kyseisen kaatopaikkaluokan liukoisuusraja-arvot. Maarakennusasetus antaa puolestaan liukoisuus- ja pitoisuusraja-arvot maarakennuksessa hyödynnettäville jakeille. Pohjakuonan hyötykäyttö vaatii kuitenkin aina ympäristöluvan. Hyötyvoimalan pohjakuonasta tehtyjen analyysien perusteella voidaan todeta, että käsiteltyä pohjakuonaa olisi mahdollista käyttää esimerkiksi kenttien ja kaatopaikkojen pohjarakenteissa sekä kaatopaikoilla jätetäyttöjen peitemaina. Pohjakuonan hyödyntäminen kaukolämpötöiden maarakennuksessa vaatii vielä lisätutkimuksia putkien korroosioriskin osalta. Diplomityön tuloksena kehitettiin toimintamalli, jonka avulla Kotkan Energia Oy:n on mahdollista säästää kuonan käsittelyn ja hyötykäytön kustannuksissa. Kustannuksiltaan parhaaksi vaihtoehdoksi osoittautui kuonan käsittely omalla biopolttoaineiden välivarastolla sekä käsitellyn pohjakuonan hyödyntäminen välivaraston pohjarakenteissa. 

Environmental behavior of soils and mixtures of soil-whitewash mud

The present study sought to observe the behavior of soils in natural state and in mixtures, in different ratios, with the industrial solid residue called whitewash mud. The work was conducted with samples of typical soils from the region of Alagoinhas, Bahia-Brazil. Wet chemical analysis and atomic absorption spectrophotometry were used in order to obtain the classification of the industrial solid residue. Solubilization and leaching tests were performed and X-ray diffraction and electron microscopy techniques were carried out. The results showed that the whitewash mud was classified as non-inert, but with great capacity of heavy metal retention largely owed to the kaolinite and goethite presence in the clay fraction of the soils, making it difficult to have heavy metals readily available for exchange.

Corrosion behaviour of boiler tube materials during combustion of fuels containing Zn and Pb

Många förbränningsanläggningar som bränner utmanande bränslen såsom restfraktioner och avfall råkar ut för problem med ökad korrosion på överhettare och/eller vattenväggar pga. komponenter i bränslena som är korrosiva. För att minimera problemen i avfallseldade pannor hålls ångparametrarna på en relativt låg nivå, vilket drastiskt minskar energiproduktionen. Beläggningarna i avfallseldade pannor består till största delen av element som är förknippade med högtemperaturkorrosion: Cl, S, alkalimetaller, främst K och Na, och tungmetaller som Pb och Zn, och det finns också indikationer av Br-förekomst. Det låga ångtrycket i avfallseldade pannor påverkar också stålrörens temperatur i pannväggarna i eldstaden. I dagens läge hålls temperaturen normalt vid 300-400 °C. Alkalikloridorsakad (KCl, NaCl) högtemperaturkorrosion har inte rapporterats vara relevant vid såpass låga temperaturer, men närvaro av Zn- och Pb-komponenter i beläggningarna har påvisats förorsaka ökad korrosion redan vid 300-400 °C. Vid förbränning kan Zn och Pb reagera med S och Cl och bilda klorider och sulfater i rökgaserna. Dessa tungmetallföreningar är speciellt problematiska pga. de bildar lågsmältande saltblandningar. Dessa lågsmältande gasformiga eller fasta föreningar följer rökgasen och kan sedan fastna eller kondensera på kallare ytor på pannväggar eller överhettare för att sedan bilda aggressiva beläggningar. Tungmetallrika (Pb, Zn) klorider och sulfater ökar risken för korrosion, och effekten förstärks ytterligare vid närvaro av smälta. Motivet med den här studien var att få en bättre insikt i högtemperaturkorrosion förorsakad av Zn och Pb, samt att undersöka och prediktera beteendet och motståndskraften hos några stålkvaliteter som används i överhettare och pannväggar i tungmetallrika förhållanden och höga materialtemperaturer. Omfattande laboratorie-, småskale- och fullskaletest utfördes. Resultaten kan direkt utnyttjas i praktiska applikationer, t.ex. vid materialval, eller vid utveckling av korrosionsmotverkande verktyg för att hitta initierande faktorer och förstå deras effekt på högtemperaturkorrosion.

Effect of lead acetate on neurobehavioral development of rats

We investigated the effects of lead exposure during the pre- and postnatal period on the neurobehavioral development of female Wistar rats (70-75 days of age, 120-150 g) using a protocol of lead intoxication that does not affect weight gain. Wistar rats were submitted to lead acetate intoxication by giving their dams 1.0 mM lead acetate. Control dams received deionized water. Growth and neuromotor development were assessed by monitoring daily the following parameters in 20 litters: body weight, ear unfolding, incisor eruption, eye opening, righting, palmar grasp, negative geotaxis, cliff avoidance and startle reflex. Spontaneous alternation was assessed on postnatal day 17 using a T maze. The animals' ability to equilibrate on a beaker rim was measured on postnatal day 19. Lead intoxication was confirmed by measuring renal, hepatic and cerebral lead concentration in dams and litters. Lead treatment hastened the day of appearance of the following parameters: eye opening (control: 13.5 ± 0.6, N = 88; lead: 12.9 ± 0.6, N = 72; P<0.05), startle reflex (control: 13.0 ± 0.8, N = 88; lead: 12.0 ± 0.7, N = 72; P<0.05) and negative geotaxis. On the other hand, spontaneous alternation performance was hindered in lead-exposed animals (control: 37.6 ± 19.7; lead: 57.5 ± 28.3% of alternating animals; P<0.05). These results suggest that lead exposure without concomitant undernutrition alters rat development, affecting specific subsets of motor skills.

Zinc accumulation in phosphate granules of Ucides cordatus hepatopancreas

Amorphous phosphate granules are present in vertebrate and invertebrate organisms. The functions attributed to these structures depend on their mineral contents and organic matrix composition. In the present study we have determined zinc concentrations in the hepatopancreas of the crab Ucides cordatus from regions contaminated with zinc, and the elemental composition of hepatopancreal phosphate granules. Organisms were collected from the contaminated areas of Sepetiba Bay (SB) and Guanabara Bay (GB), and from a non-contaminated area, Ribeira Bay (RB). The first two sites are located near the metropolitan region of Rio de Janeiro city, Brazil. Atomic absorption spectroscopy (AAS) showed a significant difference (P<0.05) for zinc concentration in the hepatopancreas from organisms collected at the contaminated sites GB (210 ± 20 µg/g dry weight) and SB (181 ± 16 µg/g dry weight) compared to the non-contaminated site RB (76 ± 14 µg/g dry weight). Phosphate granules isolated from hepatopancreatic tissue were studied by electron diffraction (ED), energy dispersive X-ray analysis (EDX) and electron spectroscopic imaging (ESI). ED of granules presented no diffraction spots, indicating that these structures are in an amorphous state, while EDX of granules isolated from a contaminated area contained P, Ca and Zn. Mg, Cl and Fe were also found in some of the spectra. ESI showed that O, P and Ca were colocalized in the mineralized layers of most granules observed. The correlation between the results obtained by AAS and those obtained by microanalytical techniques suggests that the hepatopancreatic granules of U. cordatus may be related to the phenomenon of heavy metal retention.

Liver oxidative stress of the grey mullet Mugil cephalus presents seasonal variations in Ennore estuary

The objective of this study was to determine the liver oxidative stress status of grey mullets living in heavy-metal-rich polluted Ennore estuary compared with unpolluted Kovalam estuary. Fish were collected from both estuaries during the monsoon and summer seasons from October 2004 to September 2006. Fish liver homogenate (N = 20 per group) was prepared for evaluating oxidative stress parameters. Fish living in the polluted estuary had significantly higher lipid oxidation products, conjugated dienes (0.346 ± 0.017 vs 0.141 ± 0.012 DA233/mg protein), lipid hydroperoxides (0.752 ± 0.032 vs 0.443 ± 0.03 nmol/mg protein), and lipid peroxides (3.447 ± 0.14vs 1.456 ± 0.096 nmol MDA/mg protein) than those of the unpolluted estuary during the summer. In contrast, significantly lower levels of superoxide dismutase (20.39 ± 1.14 vs 53.63 ± 1.48 units/mg protein) and catalase (116 ± 6.87vs 153 ± 8.92 units/mg protein) were detected in the liver of fish from the polluted estuary (Ennore) compared to fish from the unpolluted estuary (Kovalam) during the summer. Variations in most of the oxidative stress parameters were observed between the summer and monsoon seasons, indicating the importance of seasonal variation for estuaries and their inhabitants.

Toxic effects of mercury, lead and gadolinium on vascular reactivity

Heavy metals have been used in a wide variety of human activities that have significantly increased both professional and environmental exposure. Unfortunately, disasters have highlighted the toxic effects of metals on different organs and systems. Over the last 50 years, the adverse effects of chronic lead, mercury and gadolinium exposure have been underscored. Mercury and lead induce hypertension in humans and animals, affecting endothelial function in addition to their other effects. Increased cardiovascular risk after exposure to metals has been reported, but the underlying mechanisms, mainly for short periods of time and at low concentrations, have not been well explored. The presence of other metals such as gadolinium has raised concerns about contrast-induced nephropathy and, interestingly, despite this negative action, gadolinium has not been defined as a toxic agent. The main actions of these metals, demonstrated in animal and human studies, are an increase of free radical production and oxidative stress and stimulation of angiotensin I-converting enzyme activity, among others. Increased vascular reactivity, highlighted in the present review, resulting from these actions might be an important mechanism underlying increased cardiovascular risk. Finally, the results described in this review suggest that mercury, lead and gadolinium, even at low doses or concentrations, affect vascular reactivity. Acting via the endothelium, by continuous exposure followed by their absorption, they can increase the production of free radicals and of angiotensin II, representing a hazard for cardiovascular function. In addition, the actual reference values, considered to pose no risk, need to be reduced.

Methylmercury inhibits prolactin release in a cell line of pituitary origin

Heavy metals, such as methylmercury, are key environmental pollutants that easily reach human beings by bioaccumulation through the food chain. Several reports have demonstrated that endocrine organs, and especially the pituitary gland, are potential targets for mercury accumulation; however, the effects on the regulation of hormonal release are unclear. It has been suggested that serum prolactin could represent a biomarker of heavy metal exposure. The aim of this study was to evaluate the effect of methylmercury on prolactin release and the role of the nitrergic system using prolactin secretory cells (the mammosomatotroph cell line, GH3B6). Exposure to methylmercury (0-100 μM) was cytotoxic in a time- and concentration-dependent manner, with an LC50 higher than described for cells of neuronal origin, suggesting GH3B6 cells have a relative resistance. Methylmercury (at exposures as low as 1 μM for 2 h) also decreased prolactin release. Interestingly, inhibition of nitric oxide synthase by N-nitro-L-arginine completely prevented the decrease in prolactin release without acute neurotoxic effects of methylmercury. These data indicate that the decrease in prolactin production occurs via activation of the nitrergic system and is an early effect of methylmercury in cells of pituitary origin.

Teollisuusjätteen käyttö kiinteytys-stabiloinnin sideaineena ja haitta-aineiden stabiloinnin tehostamisessa

Tässä kanditaatintyössä selvitettiin kuinka erilaiset sideaineseokset soveltuvat raskas-metallien sitomiseen 28 vuorokautta stabiloiduissa näytteistä. Työssä oletettiin teollisten jätefraktioiden käytön tehostavan eräiden metallien, kuten kupari ja sinkki, immobilisointia lievästi pilaantuneista maa-aineksista. Kokeellisessa osassa stabiloitiin Kokkolan satamasta ruopattua sedimenttiä, jonka sinkkipitoisuudet olivat ylittäneet saastuneen sedimentin ohjearvon (≥400 mg/kg). Sedimenttiin lisättiin eri sideaineseoksia ja näytteiden annettiin stabiloitua 28 vuorokautta, minkä jälkeen niistä testattiin liukenevat raskasmetallit muokatulla ravistelutestillä. Eri sideaineseoksilla saatuja tuloksia verrattiin pelkän yleissementin käyttöön. Lisäksi erillisistä näytteistä otettiin pyyhkäisyelektronimikros-koopilla (SEM) kuvia havainnollistamaan stabiloitumista. Näissä näytteissä käytettiin samoja sideaineita kuin tehdyissä kokeissa. Liukoisuustestien tuloksista voidaan huomata näytteissä ongelmalliseksi raskasmetalliksi identifioidun sinkin sitoutuvan parhaiten sementin ja kipsin sekoituksella. Myös tuhkaa sisältävät sideainesekoitukset pienensivät sinkin liukoisuutta verrattuna pelkkään yleis-sementtiin. Jatkotutkimuksissa voitaisiin testata erilaisia sideainesekoituksia betonira-kentamisessa, joilla saadaan ainakin 25 MPa lujuusarvo, pilaantunutta sedimenttiä tai maa-ainesta käyttäen.

Synthesis of nanoporous materials for preconcentration and determination of trace elements by ICP-AES ; Investigation and elimination of the memory effects of mercury, gold, silver and boron in ICP-AES

Nanoporous materials with large surface area and well-ordered pore structure have been synthesized. Thiol groups were grafted on the materials' surface to make heavy metal ion pre-concentration media. The adsorption properties ofthe materials were explored. Mercury, gold and silver can be strongly adsorbed by these materials, even in the presence of alkaline earth metal ion. Though the materials can adsorb other heavy metal ions such as lead and copper, they show differential adsorption ability when several ions are present in solution. The adsorption sequence is: mercury> == silver> copper » lead and cadmium. In the second part of this work, the memory effects of mercury, gold, silver and boron were investigated. The addition of 2% L-cysteine and 1% thiourea eliminates the problems of the three metal ions completely. The wash-out time for mercury dropped from more than 20 minutes to 18 seconds, and the wash-out time for gold decreased from more than 30 minutes to 49 seconds. The memory effect of boron can be reduced by the use of mannitol.

La Bible coulée dans le rock. Fragmentation et reconstruction du texte biblique dans la musique rock

Dans ses entretiens, George Steiner considère la musique rock et le heavy metal comme l’espéranto international des jeunes de notre époque (Steiner, Entretiens, p. 91). Or, cet espéranto porte une dimension religieuse manifeste, entre autres à travers l’usage fréquent d’images et de textes bibliques souvent passés au broyeur des guitares et des voix vociférantes. On peut se demander quelles figures construisent les fragments qui en résultent, souvent irrévérencieux voire scandaleux pour plusieurs. À travers les violences que le rock et surtout le métal infligent au texte biblique, faut-il voir des attaques contre la Bible et contre Dieu, comme le croient plusieurs chrétiens, ou, au contraire, un respect profond de la dynamique de ce texte et un usage légitime de celui-ci ? Davantage portée par la seconde hypothèse, ce texte vise à identifier les usages et les fonctions religieuses de la Bible dans la musique rock.

Making Mountains out of Molehills: works for small ensembles and solo instruments

La version intégrale de ce[te] mémoire [thèse] est disponible uniquement pour consultation individuelle à la Bibliothèque de musique de l’Université de Montréal (http://www.bib.umontreal.ca/MU).

La neurotoxicité développementale associée au méthylmercure, au plomb et aux biphényles polychlorés : l’attention et le traitement visuel à l’étude

L’influence des contaminants environnementaux (CE) a été largement étudié en contexte d’exposition aigüe et d’intoxication. Qu’en est-il d’une exposition chronique à plus faibles doses sur le développement cognitif et sensoriel des enfants? Les études longitudinales de la présente thèse ont été réalisées au Nunavik. Bien que géographiquement éloignée des centres industriels, la communauté inuite est exposée aux CE via leur transport par les courants atmosphériques et océaniques ainsi que par leur bioaccumulation dans le poisson et les mammifères marins. Puisque l’alimentation autochtone traditionnelle, notamment la chair de béluga, est encore fréquemment consommée par la communauté, une proportion substantielle d’enfants inuits est exposée in utero aux CE. Ceux-ci sont également continuellement exposés à ces agents neurotoxiques durant leur développement postnatal. Or, la variation considérable dans l’adoption de l’alimentation traditionnelle au sein de la communauté représente une opportunité pour étudier la relation entre les niveaux d’exposition aux CE et le développement cognitif et sensoriel des enfants. Bien que certains déficits aient déjà été mis en lien avec l’exposition chronique aux CE dans la littérature, la présente thèse s’intéressa à cette relation plus spécifiquement chez les enfants inuits vivant dans le Grand Nord et plus exposés aux CE en raison de leur alimentation. Par ailleurs, les protocoles qui ont été développés pour cette thèse permettront d’évaluer des aspects qui ont été peu étudiés en lien avec les CE, soit l’attention visuospatiale et le traitement visuel cérébral précoce. Dans le premier volet de cette thèse, la relation entre trois CE et l’attention visuospatiale a été étudiée à l’aide d’une version adaptée de la tâche de Posner (M.I. Posner et al., 1980). Cette tâche psychophysique a été administrée à des enfants inuits (âge moyen = 11.2 ans) dont les niveaux d’exposition au mercure (Hg), au plomb (Pb) et aux biphényles polychlorés (BPCs) ont été documentés durant les périodes pré et postnatale. Les expositions in utero au Pb et aux BPCs ont été significativement associées à de l’impulsivité et de l’inattention, respectivement, alors que l’exposition postnatale au Pb a été associée à des temps de réaction plus longs. Bien qu’aucune relation spécifique avec l’attention visuospatiale n’ait été trouvée, les résultats de cette étude suggèrent que l’exposition aux CE est associée à une diminution des capacités attentionnelles générales chez les enfants résidant au Nunavik. Dans le second volet, le traitement cérébral précoce de l’information visuelle a été examiné à l’aide de potentiels évoqués visuels auprès d’enfants de la même communauté (âge moyen = 10.9 ans). La concentration de Hg dans le sang de cordon ombilical mesurée à la naissance a été associée à une réduction de l’amplitude et à une augmentation de la latence de la composante N75. L’exposition prénatale au Pb a quant à elle été associée à un délai dans la latence de la composante N150. Les résultats obtenus suggèrent ainsi que l’exposition aux métaux lourds, en particulier durant la période gestationnelle, serait associée à des altérations dans le développement visuel. Les résultats présentés dans cette thèse soutiennent l’hypothèse selon laquelle le cerveau en développement est vulnérable lors d’une exposition chronique aux CE, et cela même à des niveaux de concentration inférieurs aux limites recommandées par les organismes de santé publique. Les résultats permettent également d’apporter un éclairage nouveau sur les déficits cognitifs et sensoriels associés aux CE.