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.

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Civil Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / Ph.D.

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The main objective of this project was to investigate and model phosphorus (P) transport in soil column studies. A model named HYDRUS-NICA was developed, by coupling a hydrological and transport model (HYDRUS-1D model) with an aqueous chemical model (non-ideal competitive adsorption - NICA), to improve the predictions of P transport in soil and water. The HYDRUS-NICA model was developed by replacing the non-linear empirical (Freundlich and Langmuir) equations of the HYDRUS-1D model with the NICA model equations. The numerical accuracy of the HYDRUS-NICA model was then evaluated by comparing the relative errors produced by the HYDRUS-NICA and HYDRUS-1D models. The results showed that the numerical schemes of the HYDRUS-NICA code are stable. / The ability of the NICA model to describe phosphate (PO4) adsorption to soil particles was tested using soils collected from agricultural fields in southern Quebec. The surface charge and PO4 adsorption capacity of these soils were measured. Results were used to estimate the NICA model parameters using a non-linear fitting function. The NICA model accurately described the surface charge of these soils and the PO4 adsorption processes. / The HYDRUS-1D model was applied to simulate water flow and PO4 transport in re-constructed soil column experiments. The HYDRUS-1D model was calibrated based on physical and chemical parameters that were estimated from different experiments. Overall, the HYDRUS-1D model successfully simulated the water flow in the columns; however, it overestimated the final adsorbed PO4 concentrations in the soil. The discrepancies in the results suggested that the HYDRUS-1D model could not account for the differences in the soil structure found in the columns, or that the Freundlich isotherm could not adequately describe PO4 adsorption. / The HYDRUS-NICA model was calibrated and validated with results from re-packed column experiments. The simulated results were then compared with results obtained by the HYDRUS-1D model. The overall goodness-of-fit for the HYDRUS-1D model simulations was classified as poor. The HYDRUS-NICA model improved significantly the prediction of PO4 transport, with the coefficient of modeling efficiency values being close to unity, and the coefficient of residual mass values being close to zero. The HYDRUS-NICA model can be used as a tool to improve the prediction of PO4 transport at the field scale.

The thesis examines the influence of irradiation time on the photochemically induced formation of particles in surface waters. It focuses on the formation of insoluble particles and their sorption properties in relation to alternating dark and light phases.

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No description available.

Phosphorus is often the limiting nutrient of primary productivity in southern Appalachian reservoirs, but its impact on higher trophic levels has not been assessed. Regression analysis was used to examine the relationship between total phosphorus concentrations and estimates of fish standing stock in Smith Mountain Lake (SML) over time and for 22 southern Appalachian reservoirs (SAR) at the same time. ln SML, which had responded to a nutrient reduction program, total phosphorus concentration and fish biomass concurrently declined over an 12-year period; phosphorus concentration accounted for one-third (cove-specific) and two-thirds (whole-Iake) of the annual variation in fish standing stock. Total phosphorus concentration was also the best predictor of fish abundance in SARs, accounting for 84% of the variation in standing stock despite great diversity in reservoir physical, chemical, and biological characteristics. Predictive power was generally higher at lower levels of the food chain (i.e. planktivores, younger fish) than for piscivores. Planktivore response to phosphorus was found to be immediate. Piscivore biomass did not vary significantly with phosphorus, owing in part to poor energy transfer up the food chain and variable management practices. Phosphorus concentration and total fish standing stock appear to have stabilized in SML since 1980. Losses in fish standing stock due to deceased fertility in SML have been partly offset by an increase in coolwater habitat. Aesthetic versus fishery benefits and the complexity of dealing with a longitudinal trophic gradient need to be considered for future management of SML. / Master of Science / incomplete_metadata

The composition of a community and the environmental conditions in which they exist fundamentally influence productivity and responses of systems to change. In the Northern Gulf of Mexico (NGoM), the relationships between nutrients, salinity, and phytoplankton populations are complex and have been changing over time. This work focuses on describing and analyzing: 1) a case study of diversity and recommendations for change within an academic institution; 2) spatial and temporal trends in surface dissolved inorganic nitrogen (DIN) and phosphorus (DIP) in the NGoM over 35 years; 3) nutrient addition experiments (NAEs) to determine prevailing NGoM surface slope region nutrient limitation; and 4) NGoM surface continental slope phytoplankton community composition and dynamics. Over time, academic institutions have not made progress toward increasing diversity, equity, and inclusion (DEI) in the geosciences. The first chapter of this work serves as a roadmap for other institutions to make progress toward ingraining DEI frameworks into the foundations of our institutional systems. Toward explaining trends in nutrients from 1985 to 2019, I compiled the largest data set of NGoM surface dissolved nutrient concentrations to date and analyzed it to delineate spatiotemporal trends and identify potential drivers of nutrient change. DIP concentrations in both the Mississippi-Atchafalaya River system (MAR) and in the NGoM increased over time, but the increase of NGoM DIP exceeded the DIP loads coming from only the MAR, suggesting additional sources of P to the NGoM. To determine nutrient controls on surface slope NGoM phytoplankton growth and populations, we calculated growth rates and pigment composition using redundancy analyses and a variety of nutrient limitation criteria for each nutrient amendment over 48 hours. Nutrient limitation criteria concluded predominant NP limitation in the NGoM, though single N and P limitation and nutrient replete conditions were also present. In individual NAEs with N and NP amendments, phytoplankton pigment changes were driven by the growth of diatoms and Synechococcus (Syn). Though release from nutrient limitation stimulated responses in some phytoplankton groups, nutrient limitation of phytoplankton growth could not fully be predicted by the criteria and response thresholds evaluated in this study. Additionally, an analysis of environmental variables and phytoplankton pigments was conducted for the surface slope region of the NGoM to determine how phytoplankton community composition varies spatially with the influence of the MAR plume using group-specific chlorophyll a (Chl-a) calculations, bivariate linear regression, multivariate redundancy analysis, and cluster analysis. The largest proportion of Chl-a occurred in the nano/microphytoplankton group, followed by Syn, with both peaking at the high and low ends of the salinity gradient. Redundancy and cluster analyses showed that nutrients and salinity alone cannot predict or subdivide phytoplankton community composition; however, with the addition of pigments, we can characterize specific regions based on shared environmental variables (i.e., low salinity, high biomass) and pigment abundance. In sum, this work produced a straightforward and reproducible guide to leading a DEI task force, the largest NGoM surface nutrient data set to date, and characterizations of NGoM continental slope nutrient limitation and pigment composition and their relation to environmental variables.

A study of phosphorus loading and water quality implications was conducted for the Oregon coastal lakes. The study was based on existing data for lake total phosphorus concentrations and for watershed land uses. A phosphorus mass-balance model was developed to predict lake total phosphorus concentrations from estimated phosphorus loading from land uses within the lake's watershed. Uncertainty in total phosphorus concentration estimates are included in the model, and model predictions are considered to be moderately to highly reliable. The Oregon coastal lake phosphorus mass-balance model was calibrated from data for 12 Oregon coastal lakes. Land use phosphorus loading coefficients for forestry, the coastal dunal aquifer, and precipitation were derived from data specific to the Oregon coastal region, while other phosphorus loading coefficients were estimated based on correlations between literature values and Oregon coastal conditions. The model may be used as an aid for land use management decisions by estimating water quality effects of projected land use changes. A case study of Mercer Lake was used to illustrate the model application. / Graduation date: 1994