Abstract of Thesis (Ph. D.)--Uppsala University, 1983. / Includes bibliographical references (p. 16).

Orientador: Ivanise Guilherme Branco / Banca: Eliana Janet Sanjinez Argandoña / Banca: Cássia Roberta Malacrida Mayer / Resumo: No Brasil, há uma grande biodiversidade de espécies de algas lóticas, Dentre as mais conhecida, encontradas em rios e riachos da região sudeste do estado de São Paulo destaca-se a Oedogonium sp. e a Nitella microcarpa var. wrightii., dois gêneros de algas verdes. Entretanto, estudos de caracterização química de extratos destas algas ainda são inexistentes. Por esse motivo destaca-se a importância deste trabalho, o qual encontra-se subdivido em dois estudos. O primeiro teve por objetivo avaliar e quantificar compostos fenólicos e capacidade antioxidade de extratos de diferentes solventes da alga Oedogonium sp. Utilizou-se um delineamento experimental de mistura para determinar a influência dos solventes e verificou-se qual desses apresentou melhor rendimento na extração desses compostos da alga em pó. O segundo estudo teve por objetivo realizar a caracterização de duas macroalgas verdes: Nitella microcarpa var. wrightii, e Oedogonium sp., através da obtenção de um extrato, com o melhor sistema de solventes obtidos no primeiro estudo. Desta forma, foi possível quantificar quanto a presença de minerais, flavonoides, umidade, carotenoides, compostos fenólicos e capacidade antioxidante. No primeiro estudo, os resultados sugeriram que a mistura acetona-etanol apresentou melhor rendimento de extração tanto para compostos fenólicos como à capacidade antioxidante. No segundo estudo, a alga Oedogonium sp. destacou-se por apresentar uma grande quantidade de carotenoides totais. Já a e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In Brazil, there is a great biodiversity of lotic algae species. Among the most well known species found in rivers and streams in the southeast region of the state of São Paulo is Oedogonium sp. and Nitella microcarpa var. Wrightii., Two genus of green algae. However, studies of chemical characterization of extracts of these algae are still non existent. For this reason the importance of this work is highlighted, which is subdivided in two studies. The first one had the objective to evaluate and quantify phenolic compounds and antioxidant capacity of extracts of different solvents of the algae Oedogonium sp. An experimental design of the mixture was used to determine the influence of the solvents and it was verified which of them presented better yield in the extraction of these compounds from the powdered seaweed. The second study aimed to characterize two green macroalgae: Nitella microcarpa var. Wrightii, and Oedogonium sp., by obtaining an extract, with the best solvent system obtained in the first study. In this way, it was possible to quantify the presence of minerals, flavonoids, moisture, carotenoids, phenolic compounds and antioxidant capacity. In the first study, the results suggested that the acetone-ethanol-water mixture had a better extraction yield for both phenolic compounds and antioxidant capacity. In the second study, the alga Oedogonium sp. was characterized by a large amount of total carotenoids. The other alga, of the species Nitella microcarpa var... (Complete abstract click electronic access below) / Mestre

Routine monitoring of algae in inland waters in southern Africa is a critical element in assessing the efficacy of eutrophication management options. Several authors have indicated that single point samples are not necessarily representative of conditions throughout the water body and some have suggested remote sensing as a means of overcoming this problem. Remote sensing of algae normally involves deriving the empirical relationship between radiance detected at a sensor, and contact sensed chlorophyll concentrations. Quantification of, or compensation for, contributions to the upwelling radiance other than that light reflected by the algae is critical for this approach. In southern Africa these contributions arise primarily from atmospheric effects and from scattering by sediments in the water. A review of the atmospheric correction models suggested that a cosine sun angle correction followed by dark pixel subtraction is the most feasible method to compensate for the former effects. Studies of the changes in upwelling radiance induced by addition of sediment to algal cultures indicated that subtraction of reflectance at ≈665nm from that at ≈700nm, may provide a means of compensating for the scattering by sediments. The disadvantage of this approach is that few sensor systems have narrow spectral bands centred at these wavelengths. Investigations of the nature of the reflectance from 5 algal species indicated that all had similar reflectance spectra, but the blue-green genera had a smaller peak at ≈650nm. Chlorophyll absorption at ≈665nm was evident by lower reflectance at this point, but the alga Microcystis sp. did not conform to the conceptual model of reflectance, in that reflectance at 665nm was higher at increased cell density. Spectra of natural waters confirmed the results obtained in the laboratory. Reflectance at ≈700nm showed the largest changes with increasing chlorophyll concentration and also had the highest correlations to chlorophyll concentrations. However, due to the strong absorption of these wavelengths by water, this reflectance peak only occurred when sufficient cells were found in the upper layers of water. Use of these wavelengths in remote sensing models should therefore be restricted to highly eutrophied waters. Although the reflectance spectra of different algae were similar, the amount of light scattered by each species (measured as turbidity) differed for any given chlorophyll concentration. This appeared to be due to the colonial nature of the cells and means that empirical models will be unique to the species on which they were developed. Comparisons of multispectral photography (MSP) and LANDSAT MSS imagery indicated the MSP data had higher correlations with chlorophyll concentrations than did the MSS data. Chlorophyll simulations from a test set of data using ordinary multiple regression showed that the MSP imagery had mean errors of 7.3M9/I, while that for the MSS imagery was 7.4M9/I. Similar tests using the canonical procedure produced larger mean errors of 9M9/I and 12M9/I for the MSP and MSS data respectively. This was due to the fact that the canonical procedure is not suitable for the spectral band widths of these sensors. In spite of similar simulation accuracies, the MSS imagery produced very patchy synoptic views. This was due to the lower variance (radiometric resolution) in the LANDSAT MSS data. This appears to be the most important criterion for accurate chlorophyll mapping in inland waters. Development of a single multidate algorithm for southern Africa is not yet feasible, and routine monitoring of chlorophyll using these techniques is impractical. However acceptable chlorophyll maps are possible if the model is recalibrated for each occasion and the sensor used has a high radiometric resolution.

No description available.

Periphytic algae biomass, periphyton taxonomic composition and water quality were monitored from October, 1978 through October, 1979 in three experimental ponds on the University of Central Florida campus, Orlando, Florida. Differences in the abundance and seasonal periodicity of phytoplankton in the ponds presumably arose from intrinsic differences in the nature of the pond sediments. Ceramic tile and pressboard wood artificial substrates were sampled at two-month intervals to provide estimates of periphyton biomass and productivity; there was no significant difference in algal biomass on wood and tile substrates. Algal productivity on continuous-immersion (cumulative) substrates which supported a large accumulation of periphyton was substantially lower than productivity on uncolonized substrates immersed during the same period. thus indicated the existence of a carrying capacity for the periphyton community. Turbidity, which was largely determined by phytoplankton abundance, was significantly higher in Pond 2 (7.50 FTU) than in Ponds 1 and 3 (2.60 and 2.53 FTU, respectively) and resulted in reduced light penetration and development of a heterotrophic periphyton community in Pond 2. The algal flora of Pond 2 was dominated by small conditions, whereas Ponds 1 and 3 possessed periphyton communities dominated by large, filamentous green algae indicative of "clean" water.

The occurrence of taste-and-odor problems that are caused by algal metabolites in water supplies has been well documented. Several commonly occurring odor-producing algae were selected and cultured for this research. Initial studies involved the algal cells and cell-free media from cultures grown under fairly optimal conditions. Gas chromatography-mass spectrometry (GC-MS) and flavor profile analyses (FPA) were performed to identify the organic compounds produced by the algae and their respective odors. Three of the algal cultures underwent additional studies that investigated the effects of selected changes in culture conditions on both population growth and compound production. Experimental variables included nitrogen concentration (ammonium, nitrate, and nitrite), phosphorus concentration, light intensity, and temperature. Parametric and nonparametric analyses were performed to identify the environmental factors that had a significant effect on algal production, accumulation, and release of taste-and-odor compounds. The organic compounds were extracted from both the algal cells and the cell-free media. Continuous liquid-liquid extraction and Kuderna-Danish concentration (CLLE-KD) was an effective and reliable method for the isolation and concentration of a broad range of organic compounds. The plot of flavor profile analysis (FPA) results obtained for odor standards adhered to the Weber-Fechner Law (W-F) over the range of concentrations evaluated. The odor intensities of algal cultures were generally lower than the odor intensities predicted from the W-F plot of the compound standards. Masking of the odor associated with one compound by the odor associated with another was observed. Odors produced by young algal cultures (e.g., low population densities) were detected in FPA samples at compound concentrations below the limits of detection by GC-MS. Anabaena laxa retained most of the geosmin it produced within the algal cells. Phormidium sp. produced more 2-methylisoborneol (MIB) than geosmin, and the alga retained only a relatively small amount of either compound within the cells. Synura petersenii produced more 2t,4c,7c-decatrienal than 2t,6c-nonadienal, and large fractions of the concentrations produced were retained within the algal cells. Various combinations of nutrient reduction, early algal-bloom within-reservoir treatment, and removal of algal cells prior to oxidation were suggested as likely methods by which odor problems may be reduced. / Ph. D.

Pigment-based chemotaxonomy uses relative amounts of photosynthetic pigments (biomarkers) within algae samples to determine the algal class composition of each sample. Chemotaxonomy has been applied successfully to phytoplankton communities, but its efficacy for periphyton has not yet been established. This study examined the ability of simultaneous linear equations (SLE), CHEMTAX, and the Bayesian Compositional Estimator (BCE) to determine algal class composition in Florida Everglades periphyton. The methods were applied to artificial datasets, mixed lab cultures of known composition, and Everglades periphyton samples for which microscopic biovolume data was available. All methods were able to return accurate sample compositions for artificial data and mixed lab cultures. Correlation between pigment methods and microscopic results for natural periphyton samples was poor. SLE and CHEMTAX returned similar results for all samples while BCE performed less well. / by Jamie L. Browne. / Thesis (M.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

No description available.

The objective of this thesis was to construct general models to predict pollutant fluxes in limnoplankton by incorporating characteristics of the organism and the structures of the chemical. A two-compartmental pharmacokinetic model was used to quantify the pollutant uptake, depuration and intercompartmental exchanges. The model pollutants were phosphorus and 22 organic chemicals. / The rate constants of phosphorus uptake, excretion and intercompartmental changes by algae and cladocerans decreased with cell volume or body size raised to a power close to $-$0.25, except the intercompartmental exchanges for cladocerans which showed more negative slopes. In contrast, uptake, excretion and internal exchange rates per individual increased with cell size or body weight to a power similar to 0.75 with a similar exception for the cladoceran intercompartmental exchanges, which had slopes $<$0.75. / Bioconcentration factors, rate constants and flux rates of uptake and intercompartmental exchange from metabolic pool to structural pool of 22 $ sp{14}$C-labelled organic toxicants by Chlorella pyrenoidosa and Daphnia magna were positively correlated with the octanol/water partition coefficient, molecular weight, parachor, connectivity index, boiling point and melting point, and negatively with aqueous solubility. However, those of elimination and internal transfer from structural pool to metabolic pool showed opposite changes. Comparisons of pharmacokinetic parameters between Daphnia and Chlorella demonstrated that, although all kinetic parameters displayed similar patterns, the relative magnitudes of each corresponding parameters were significantly different between two species.

Thesis (Ph.D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 53-01, Section: B, page: 0160. Supervisor: J. R. Kramer.