Browsing by Author "Monteiro, Cristina M."
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- An approach to effluent bioremediation: cadmium removal by Desmodesmus pleiomorphusPublication . Monteiro, Cristina M.; Castro, Paula M. L.; Malcata, F. Xavier
- Aproveitamento de águas pluviais em edifícios com coberturas verdesPublication . Monteiro, Cristina M.; Castro, Paula M. L.
- Aromatic plants for water treatment in Green roofs technologyPublication . Monteiro, Cristina M.; Calheiros, Cristina; Castro P. M. L, Paula M. L
- Aromatic plants for water treatment in Green roofs technologyPublication . Monteiro, Cristina M.; Calheiros, Cristina; Castro, Paula M. L.
- Biosorption of zinc by isolated consortia of microalgaPublication . Monteiro, Cristina M.; Castro, Paula M. L.; Malcata, F. Xavier
- Biosorption of zinc ions from aqueous solution by the microalga Scenedesmus obliquusPublication . Monteiro, Cristina M.; Castro, Paula M. L.; Malcata, F. XavierAquatic environments are often exposed to toxic heavy metals, which gain access to the food chain via microalgae and may cause severe problems at higher trophic levels. However, such a metabolic specificity can be taken advantage of in bioremediation strategies. The potential of a novel wild strain of Scenedesmus obliquus, previously isolated from a heavy metal-contaminated site in northern Portugal, to remove Zn from aqueous solutions was thus studied, using several initial concentrations. The removal extent reached its maximum by 1 day: 836.5 mg Zn/g biomass, at the initial concentration of 75 mg/L, mainly by adsorption onto the cell surface. Comparative studies encompassing a commercially available strain of the same microalgal species led to a maximum removal extent of only 429.6 mg Zn/g biomass, under identical conditions. Heat-inactivated cells permitted a maximum removal of 209.6 mg Zn/g biomass, at an initial concentration of 50 mg Zn/L. The maximum adsorption capacity of Zn, estimated via Langmuir's isotherm, was 330 mg Zn/g biomass. Finally, Zn removal was highest at pH 6.0-7.0. It was proven, for the first time, that such a wild microalga can uptake and adsorb Zn very efficiently, which unfolds a particularly good potential for bioremediation. Its performance is far better than similar (reference) species, especially near neutrality, and even following heat-treatment.
- Cadmium removal by two strains of desmodesmus pleiomorphus cellsPublication . Monteiro, Cristina M.; Castro, Paula M. L.; Malcata, F. XavierThe capacity of microalgae to accumulate heavy metals has been widely investigated for its potential applications in wastewater (bio)treatment. In this study, the ability of Desmodesmus pleiomorphus (strain L), a wild strain isolated from a polluted environment, to remove Cd from aqueous solutions was studied, by exposing its biomass to several Cd concentrations. Removal from solution reached a maximum of 61.2 mg Cd g−1 biomass by 1 day, at the highest initial supernatant concentration used (i.e., 5.0 mg Cd L−1), with most metal being adsorbed onto the cell surface. Metal removal by D. pleiomorphus (strain ACOI 561), a commercially available ecotype, was also assessed for comparative purposes; a removal of 76.4 mg Cd g−1 biomass was attained by 1 day for the same initial metal concentration. Assays for metal removal using thermally inactivated cells were also performed; the maximum removal extent observed was 47.1 mg Cd g−1 biomass, at the initial concentration of 5 mg Cd L−1. In experiments conducted at various pH values, the highest removal was achieved at pH 4.0. Both microalga strains proved their feasibility as biotechnological tools to remove Cd from aqueous solution.
- Capacity of simultaneous removal of zinc and cadmium from contaminated media, by two microalgae isolated from a polluted sitePublication . Monteiro, Cristina M.; Castro, Paula M. L.; Malcata, F. XavierSeveral aquatic environments have been contaminated with heavy metals dumped via industrial effluents. Numerous studies have been published regarding the removal of single metals from aqueous solutions by microalgal biomass. However, such studies do not reflect the actual problem associated with industrial effluents because usually more than one metal species is present. Here we studied the biosorption capacity of Zn2+ and Cd2+ as single- and binary-metal systems by two microalgae, Scenedesmus obliquus and Desmodesmus pleiomorphus, isolated from a polluted site in Northern Portugal. For each metal independently, D. pleiomorphus showed a higher metal sorption capacity than S. obliquus, at concentrations ranging from 60 to 300 mg/l (except 150 mg(Cd)/l). Maximum amounts of Zn2+ and Cd2+ removed were 22.3 and 60.8 mg/g by S. obliquus, and 83.1 and 58.6 mg/g by D. pleiomorphus. In binary-metal solutions, S. obliquus was in general able to remove Zn2+ to higher extents than Cd2+, whereas the opposite was observed with D. pleiomorphus. The simultaneous uptake of Zn2+ and Cd2+ by both microalgae was considerably lower than that of their single-metal counterparts, at equivalent concentrations. Although microalgal uptake from binary-metal solutions was lower than from single-metal ones, the wild microalgae selected were able to efficiently take up mixtures of Zn2+ and Cd2+ up to 300 mg/l of both metals-thus materializing a promising bioremediation vector for polluted waters.
- Characterization of desmodesmus pleiomorphus isolated from a heavy metal-contaminated site: biosorption of zincPublication . Monteiro, Cristina M.; Marques, Ana P. G. C.; Castro, Paula M. L.; Malcata, F. XavierMicroalgae have been proven efficient biological vectors for heavy metal uptake. In order to further study their biosorption potential, a strain of Desmodesmus pleiomorphus (L) was isolated from a strongly contaminated industrial site in Portugal. Under different initial Zn2? concentrations, metal removal by that strain reached a maximum of 360 mg Zn/g biomass after 7 days, at 30 mg Zn/l, after an initial rapid phase of uptake. Comparative studies were carried out using a strain of the same microalgal species that is commercially available (ACOI 561): when exposed to 30 mg Zn/l, it could remove only 81.8 mg Zn/g biomass. Biosorption experiments using inactivated biomass of the isolated strain reached a maximum Zn2? uptake of 103.7 mg/g. Metal removal at various initial pH values was studied as well; higher removal was obtained at pH 5.0. The microalga strain L, isolated from the contaminated site, exhibited a much higher removal capacity than the commercial strain, and the living biomass yielded higher levels of metal removal than its inactivated form.
- Divulgação científica através de modelos e laboratórios escolares de paisagem na área da biotecnologia - Ecotecnologias para a SociedadePublication . Calheiros, Cristina S. C.; Monteiro, Cristina M.; Moreira, Helena; Ricardo, Amadeu; Calafate, Luis; Castro, Paula M. L.O papel da Universidade é plural e diverso, transcendente à geração e transmissão de conhecimento ao nível do ensino superior. Uma aproximação entre as Universidades e as Escolas e a comunidade em geral estimula a curiosidade e inquietude científica, o espírito crítico e o processo criativo quer de alunos quer do cidadão comum. Ao nível universitário, com o intuito de potenciar a divulgação do conhecimento e inovações científicas, existem vários canais ou meios de comunicação que podem ser explorados. Na área da biotecnologia a utilização do trabalho experimental, através de maquetes e modelos como forma de comunicar ciência, é muitas vezes tida em consideração em exposições, divulgação científica nas escolas e demonstração nas respetivas instituições. Os modelos têm um papel fulcral como ferramentas de trabalho e facilitadores do processo de criação científica, funcionando como representações da realidade e dando uma perceção conceptual a três dimensões. O desenvolvimento de modelos estabelece a mediação entre o real e o imaginário, potenciando a construção e evolução do conhecimento assim como a reconstrução de modelos mentais. Para além de por si só serem veículos de divulgação, como anteriormente referido, o próprio processo de construção e concepção de modelos em grupo facilita a colaboração entre estudantes, investigadores, professores e alunos. Modelos concretos são especialmente úteis na educação da ciência entre alunos mais jovens. Numa outra vertente, a possibilidade de se promover o ensino das ciências em contexto de laboratório escolar de paisagem complementa o conhecimento adquirido tendo um caracter de continuidade e melhoria da aprendizagem dos alunos para o desenvolvimento sustentável. Estes laboratórios propiciam a investigação escolar num ambiente multifacetado em contexto real, tirando partido da multifuncionalidade da paisagem. O presente trabalho pretende dar a conhecer dois projetos universitários em que a divulgação científica e o trabalho experimental na área da biotecnologia ambiental conjugam uma abordagem de ensino-aprendizagem das ciências. Estes projetos - leitos de plantas e telhados verdes (ecotecnologias) - através da sua interação sequencial com i) modelos deles mesmos à escala laboratorial, e ii) com uma visita a projetos-piloto, à escala real, estabelecidos e em funcionamento, no formato de laboratório escolar da paisagem, permitem que haja uma perceção multidisciplinar e holística destes sistemas com aplicação prática e funcional, enfatizando princípios de sustentabilidade.