CARACTERIZAÇÃO DO POTENCIAL DE ABSORÇÃO DO DIÓXIDO DE CARBONO ATMOSFÉRICO POR MICROALGAS UTILIZADAS NA AQÜICULTURA PARA A GERAÇÃO DE UM MECANISMO DE DESENVOLVIMENTO LIMPO (MDL).
The increase in atmospheric CO2 concentration in the last years has intensified the "greenhouse effect". Due to their high carbon fixation rates, the large-scale cultivation of microalgae, under semi-controlled conditions, appears as an alternative to diminish the CO2 levels in the atmosphere. High costs of microalgae production affects the aquaculture profitability. To increase the production yield and reduce costs new research is necessary to find more productive microalgae species. The main objective of this study was to determine which phytoplankton species used in aquaculture that present the highest CO2 uptake rates, as well as commercial value and that could be produced in large-scale systems. The experiments were conducted with the species Nannochloropsis oculata (Droop) Hibberd, 1955), Chaetoceros affinis Lauder, 1864, C. muelleri Lemmermann, 1898, Phaeodactilum tricornutum Bohlin, 1897, Skeletonema costatum (Greville) Cleve, 1873, Thalassiosira fluviatilis Hustedt, 1926, T. pseudonana (Husted) Hasle & Heimdal, 1970), Tetraselmis chuii Butcher, 1958, T. tetrathele (G.S. West) Butcher 1959 and Isochrysis galbana Parke, 1949 . The cells were kept in f/2 medium, constant temperature (optimum of each species), light intensity of ca. 100 ?mol/m-2/s-1 and 12L/12D photoperiod. Primary production measurements were conducted in different light intensities using oxygen and 14C (dissolved, particulate and total production) methods. Measurements were carried out when culture were in the LOG phase. The Photosynthetic Quotient and lipid fraction of most productive species were also determined. N. oculata, S. costatum e C. muelleri reached the highest growth yield, while C. affinis was the less productive species. N. oculata and I. galbana showed the highest oxygen production rates, while N. oculata e T. fluviatilis presented the highest carbon fixation rates. The most species showed PQ values bigger than 1.0. According to the results of growth and primary production rates, four species showed high potential for large-scale production: N. oculata, S. costatum, T. fluviatilis and I. galbana. Since N. oculata and S. costatum showed highest growth rates under low light intensity, these species could be cultivated during periods of low luminosity. On the other hand, T. fluviatilis and I. galbana, light adapted species, could be grown during spring/summer periods. Furthermore, the results indicate that N. oculata produces high amounts of lipid and fatty acid, indicating its great capacity for biofuels production .
Advisor:Paulo Cesar Oliveira Vergne de Abreu; Clarisse Odebrecht; Daniel Conde Scalone; Virginia Maria Tavano Garcia
School:Fundação Universidade Federal do Rio Grande
Source Type:Master's Thesis
Keywords:microalgas produção primária fotossíntese carbono aquicultura
Date of Publication:02/28/2005