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Previous issue date: 2016-02-23 / FAPERJ / Nowadays water contamination by heavy metals is an increasingly common problem, mainly due to the intensity of human activities, such as industrial, which often discard these environments their effluents enriched with these elements. In this scenario, this work was to evaluate the potential of water lettuce (Pistia stratiotes) in the decontamination of water contaminated by heavy metals zinc (Zn) and Cadmium (Cd). For that, this research was divided into three chapters. In the first chapter, it was evaluated the ability to biosorption of heavy metals by dry matter of water lettuce where laboratory adsorption isotherms were carried out with five increasing doses of Zn contamination (1.8; 18; 50; 79 and 105 mg L-1) and 4 doses of Cd (0.01, 0.1, 1 and 10 mg L-1) in nine sampling times (1, 3, 6, 12, 24, 36, 48, 60 and 72 hours). The results showed that the dry biomass of water lettuce has biosorption capacity of the metals analyzed, enhanced by increasing the contact time with the solution. This conclusion was also demonstrated by determining the isothermal linear model, which indicates a high affinity of the adsorbent for the adsorbate. Changes in the morphology of the biomass were demonstrated by scanning electron microscopy images (SEM) before and after biosorption. In the second chapter it was evaluated the potential fitoextrator of water lettuce grown in increasing doses of Zn and Cd (separately) and the physiological response of the plant to this contamination. The experiment evaluated 4 doses of contamination of each metal (Zn = 0, 1.8, 18 and 180 mg L-1 and Cd = 0, 0.1, 1 and 10 mgL-1) and cultivation time 4 (24, 48, 72 and 168 hours). In each survey were analyzed: heavy metal content in the solution, root and aerial part of the plant; content of photosynthetic pigments by direct and indirect method and photosynthetic efficiency by transient fluorescence of chlorophyll a. The results showed that water lettuce has high potential to absorb and accumulate heavy metals in their tissues, preferably in the roots, thus promoting the maintenance of the pigment synthesis and photosynthetic efficiency in most doses tested. This absorption was enhanced with increasing time of cultivation, which increased the translocation of metals to shoot and carotenoid synthesis for the protection of the photosynthetic apparatus. Higher doses of the metals had their photosynthetic efficiency decreased. In the third section it was evaluated the kinetics of absorption of heavy metals by water lettuce to it have been installed to separate Zn and Cd experiments with two different concentrations of each metal (Zn = 18 and 1.8 and 0.1 Cd and 1.0 mg L-1), with three repetitions each, totaling 12 experimental units (6 units for each element). Aliquots of the solutions and measurement of pH were carried out at certain times until stabilization of the levels of metals in the solution. At the end, the biomass production, the levels of metals and the kinetic parameters of absorption (Km and Vmax) were evaluated. The results showed that the pH of the solutions was not affected by the cultivation of water lettuce and the highest Zn and Cd absorption rates were found in larger doses contamination of the solution. Biomass production was negatively affected by contamination, but these results did not affect the rate of absorption of metals by plants. Based on all the results it can be concluded that the water lettuce has potential for remediation of water bodies contaminated by heavy metals Zn and Cd, both with its dry biomass as for its in vivo cultivation. / Atualmente a contamina??o da ?gua por metais pesados ? problema cada vez mais frequente, principalmente devido a intensidade das atividades antr?picas, como as industriais, que muitas vezes descartam nesses ambientes seus efluentes enriquecidos com esses elementos. Esse trabalho teve como objetivo avaliar o potencial da Alface-d??gua (Pistia stratiotes) na descontamina??o de ?guas contaminadas pelos metais pesados zinco (Zn) e c?dmio (Cd). A pesquisa foi dividida em 3 cap?tulos. No primeiro, foi avaliada a capacidade de biossor??o de metais pesados pela mat?ria seca da Alface-d??gua, onde foram realizadas isotermas de adsor??o em laborat?rio, com cinco doses crescentes de contamina??o por Zn (1,8; 18; 50; 79 e 105 mg L-1) e 4 doses de Cd (0,01, 0,1, 1 e 10 mg L-1) em nove tempos de coleta (1, 3, 6, 12, 24, 36, 48, 60 e 72 horas). Os resultados mostraram que a biomassa seca da Alface-d??gua possui capacidade de biossor??o dos metais analisados, potencializada pelo aumento do tempo de contato com a solu??o. Tal conclus?o tamb?m foi demonstrada pela determina??o do modelo isot?rmico linear, que indica alta afinidade do adsorvente pelo adsorbato. Altera??es na morfologia da biomassa foram observadas na microscopia eletr?nica de varredura (MEV) antes e depois da biossor??o. No segundo cap?tulo foi avaliado o potencial fitoextrator da Alface-d??gua cultivada em doses crescentes de Zn e Cd (separadamente) e as resposta fisiol?gicas da planta a essa contamina??o. O experimento avaliou 4 doses de contamina??o de cada metal (Zn = 0; 1,8; 18 e 180 mg L-1 e Cd = 0; 0,1; 1 e 10 mg L-1) e 4 tempos de cultivo (24, 48, 72 e 168 horas). Em cada coleta foram analisados: teores de metais pesados na solu??o, raiz e parte a?rea da planta; teores de pigmentos fotossint?ticos por m?todo direto e indireto e efici?ncia fotossint?tica atrav?s da fluoresc?ncia transiente da clorofila ?a?. Os resultados mostraram o elevado potencial da Alface-d??gua em absorver os metais pesados e acumular em seus tecidos, preferencialmente nas ra?zes, o que favoreceu a manuten??o da s?ntese de pigmentos e a efici?ncia fotossint?tica na maioria das doses testadas. Essa absor??o foi potencializada com o tempo de cultivo, que aumentou a transloca??o dos metais para parte a?rea e a s?ntese de carotenoides para prote??o do aparato fotossint?tico. As maiores doses dos metais tiveram sua efici?ncia fotossint?tica diminu?da. No terceiro cap?tulo foi avaliada a cin?tica de absor??o dos metais pesados pela Alface-d??gua, sendo instalados experimentos separados para Zn e Cd, com duas concentra??es diferentes de cada metal (Zn =1,8 e 18 e Cd 0,1 e 1,0 mg L-1), com 3 repeti??es cada, totalizando 12 unidades experimentais (6 por elemento). Al?quotas das solu??es e aferi??o do pH foram realizadas em tempos determinados at? a estabiliza??o dos teores dos metais na solu??o. Ao final foram avaliados a produ??o de biomassa, os teores de metais e os par?metros cin?ticos de absor??o (Km e Vmax). Os resultados mostraram que o pH das solu??es n?o foi afetado pelo cultivo da Alface-d??gua e que as maiores velocidades de absor??o de Zn e Cd foram encontradas nas maiores doses de contamina??o da solu??o. A produ??o de biomassa foi afetada negativamente pela contamina??o, por?m esses resultados n?o interferiram na velocidade de absor??o dos metais pela planta. Com base em todos os resultados pode-se concluir que a Alface-d??gua apresenta potencial para remedia??o de corpos h?dricos contaminados pelos metais pesados Zn e Cd, tanto com sua biomassa seca como pelo seu cultivo in vivo.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:jspui/2346 |
| Date | 23 February 2016 |
| Creators | RODRIGUES, Ana Carolina Dornelas |
| Contributors | Amaral Sobrinho, Nelson Moura Brasil do, Santos, Fabiana Soares dos, Santos, Andr? Marques dos, Amaral Sobrinho, Nelson Moura Brasil do, Pinho, Camila Ferreira de, Silva, Leonardo Duarte Batista da, Pereira, Ana Carolina Callegario, Tavares, S?lvio Roberto de Lucena |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Programa de P?s-Gradua??o em Ci?ncia, Tecnologia e Inova??o em Agropecu?ria, UFRRJ, Brasil, Pr?-Reitoria de Pesquisa e P?s-Gradua??o |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFRRJ, instname:Universidade Federal Rural do Rio de Janeiro, instacron:UFRRJ |
| Rights | info:eu-repo/semantics/openAccess |
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