Thesis--Rijksuniversiteit, Leiden. / Bibliography: p. 119-122.

published_or_final_version / Botany / Doctoral / Doctor of Philosophy

A knowledge of the allometry of algal growth and respiration can be applied to biomass-size distribution models which are in turn used in the prediction of fish yield and ecosystem studies. However, the scaling exponents reported in the literature are variable. This variation may be attributed to differences in the expression of cell size and phylogeny, but could also reflect small sample size which underlie most published regressions. This thesis establishes the allometry of algal growth and respiration based on a larger sample taken from the literature, and evaluates the effects of differences in gross taxonomy and in the expression of cell size on these relations. Allometric relations based on cell carbon appear more consistent with relations from other taxa than those based on cell volume, reflecting the size dependence of algal elemental composition which does not occur in most other taxa. The allometric relation of algal respiration (R in pl O$ rm sb2 cdot cell sp{-1} cdot hr sp{-1})$ was found to be R = 0.030C$ sp{0.93}$ where C is cell carbon content in pg C$ rm cdot cell sp{-1}$. Among the 6 divisions studied (Chlorophyta, Chrysophyta, Cyanophyta, Euglenophyta, Pyrrophyta, Rhodophyta), chlorophytes, euglenophytes and rhodophytes exhibited different respiration-size relation but separate relations were not developed for each of those groups due to patterns in residuals or small sample sizes. The specific rate of algal growth ($ mu$ in divisions$ cdot$day$ sp{-1}$) also depends on size and it is found to be $ mu$ = 3.45C$ sp{-0.21}.$ All taxa studied here (Chlorophyta, Chrysophyta, Pyrrophyta) have similar scaling exponents for growth but Pyrrophyta have significantly lower growth rates than other algae of similar size.

No description available.

The primary objective of this research was to determine if changes in iron availability influence the periodicity of blue-green algal growth. A secondary goal was to resolve how iron availability was related to events such as calcite (calcium carbonate) precipitation and sediment nutrient release. The biogeochemical regulation of blue-green algal succession was studied in three eutrophic hardwater lakes located upon the Thompson Plateau in south-central British Columbia. The experimental approaches included iri situ bottle and limnocorral experiments, sediment core analysis, monitoring of seasonal changes in water chemistry, and whole-lake manipulation by hypolimnetic aeration, or calcium hydroxide addition. Growth and primary production bioassays were used to evaluate iron availability. Microbial chelators were isolated from algal cultures and lake water, quantified by a chelation assay, and used to determine their in situ effects on algal productivity and bacterial heterotrophy. Microbes were able to regulate the bioavailability of iron. Algal siderophore isolates were rapidly assimilated in lake water and they were highly specific for iron chelation. Moreover, chelator concentrations in Black Lake usually exceeded the dissolved iron concentration. Algae excreted chelators that could suppress growth of some other species of algae by 90%, enhance the primary production of some other algal species by 30%, or suppress the heterotrophic activity of bacteria by 14-98%. The degree of iron limitation varied greatly during the summer. In Black Lake, iron limitation was more than ten-fold more intense in early summer than in late summer. Dense blooms of blue-green algae occurred in Black Lake only after the iron content of the lake increased from 20 to more than 100 ug/L. An increase in iron concentration in the water column of the three lakes was caused by a midsummer sediment release of iron. Although sediment pyrite formation converted available iron into refractory iron in both Chain and Frisken lakes, the degree of iron limitation varied greatly among the lakes. Unlike in Black Lake, the algae in Chain Lake were not limited by iron availability. Phosphorus solubility was a good index of iron availability. Black and Frisken lakes had too little iron for iron phosphate to precipitate, but the higher iron concentration in Chain Lake regulated phosphorus solubility. The differences among lakes was primarily a function of external iron loading, not sediment iron release. Chain Lake received 10³ more iron per m² than Frisken or Black lakes. Carbonate equilibria integrated the microbial responses to iron enrichment. When iron availability was increased in the epilimnion of Black Lake, algal productivity was enhanced which resulted in an increase in pH and the coprecipitation of more calcite and phosphorus than in control treatments. The precipitation of calcite could sediment as much as 90% of the algae and 97% of the phosphorus from the epilimnion. The hypolimnia of the iron-enriched limnocorrals had the lowest pH and highest dissolution of precipitated phosphorus. Three reactions, iron chelation, sediment iron release, and calcite precipitation, can regulate much of the periodicity of blue-green algal growth in hardwater lakes. / Science, Faculty of / Zoology, Department of / Graduate

This project was designed to investigate the effects of carbon dioxide (CO2) levels on the growth and pigment ratios (chemotaxonomy) of freshwater algal species typical to the south Florida surface waters. Green algae, diatoms, and cyanobacteria were cultured under 400 or 800 ppm CO3 in air for several weeks. Growth monitoring used a cell counter, hemocytometer, and chlorophyll fluorescence. Pigments were analyzed using HPLC-PDA. Experiments with certified CO2 concentrations (400, 600, 800, 1200 ppm) were conducted with helium degassed ultrapure water and each of three culture media. Theoretical and experimental pH values with water matched exactly. However, each culture media proved to exhibit significant buffer capacity. Cell growth monitoring was problematic except for the cyanobacterium Microcystis aeruginosa. That species responded to increased CO2 (800 ppm) with increased growth rates as predicted. The other species gave erratic results mainly due to difficulties in obtaining valid consistent cell counts. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Civil Engineering. / Microfiche copy available in Archives and Engineering. / Bibliography: leaves 63-64. / M.S.

With world crude oil reserves decreasing and energy prices continually increasing, interest in developing renewable alternatives to petroleum-based liquid fuels has increased. An alternative that has received consideration is the growth and harvest of microalgae for the production of biodiesel via extraction of the microalgal oil or lipids. However, costs related to the growth, harvesting and dewatering, and processing of algal biomass have limited commercial scale production of algal biodiesel. Coupling wastewater remediation to microalgal growth can lower costs associated with large scale growth of microalgae. Microalgae are capable of assimilating inorganic nitrogen and phosphorous from wastewater into the biomass. By harvesting the microalgal biomass these nutrients can be removed, thus remediating the wastewater. Standard methods of oil extraction require drying the harvested biomass, adding significant energetic cost to processing the algal biomass. Extracting algal lipids from wet microalgal biomass using traditional methods leads to drastic reductions in extraction efficiency, driving up processing costs. A wet lipid extraction procedure was developed that was capable of extracting 79% of the transesterifiable lipids from wet algal biomass (16% solids) without the use of organic solvents while using relatively mild conditions (90 °C and ambient pressures). Ultimately 77% of the extracted lipids were collected for biodiesel production. Furthermore, the procedure was capable of precipitating chlorophyll, allowing for the collection of algal lipids independently of chlorophyll. The capability of this procedure to extract lipids from wet algal biomass, to reduce chlorophyll contamination of the algal oil, and to generate feedstock material for the production of additional bio-products provides the basis for reducing scale-up costs associated with the production of algal biofuels and bioproducts.

This thesis describes a geographically- and temporally-resolved, integrated biological and engineering model that estimates algal biomass and lipid production under resource-limited conditions with hourly and county resolution. Four primary resources are considered in this model: sunlight, carbon dioxide, water, and land. The variation in quantity and distribution of these resources affects algae growth, and is integrated into the analysis using a Monod model of algae growth, solar insolation data, and published values for water, carbon dioxide, and land availability. Finally, lipid production is calculated by assuming oil content based on dry weight of the biomass. The model accommodates a range of growth and production scenarios, including water recycling, co-location with wastewater treatment plants and coal-fired generators, and photobioreactor type (open pond or tubular), among others. Results for every county in Texas indicate that between 86 million and 2.2 billion gallons of lipids per year can be produced statewide for the various growth scenarios. The analysis suggests that algal biomass and lipid production does indeed vary geographically and temporally across Texas. Overall, most counties are water-limited for algae production, not sunlight or carbon dioxide-limited. However, there are many nuances in biomass and lipid production by county. Counties in west Texas are typically not solar- or land-limited, but are constrained by either water or carbon dioxide resources. Consequently, counties in east Texas are limited by either water, or land (depending on the fraction of water recycling). Varying carbon dioxide concentration results in higher growth rates, but not always increased biomass and lipid production because of limitations of other resources in each county. / text

No description available.