No description available.

No description available.

No description available.

The measurement of phosphorus which is available to plants is a problem closely related to the forms and amounts of phosphorus present in soils. The fractionation of soil phosphorus, based on a series of extractions, is a procedure that has been utilized by many investigators. In this study, this scheme was utilized in an attempt to improve and evaluate the effectiveness of some methods employed in the measurement of available phosphorus to plants. / Ph. D.

A nutrient is defined as a chemical element necessary for life. In streams, phosphorus is typically one of the most important nutrients and often limits microbial (algae, bacteria, and fungi) growth. As a result, retention of phosphorus within streams largely determines productivity. Factors that influence retention include temperature (Elwood et al. 1981b), velocity (Bencala 1983), and organic matter (Mulholland et al. 1984). Watershed input-output budgets have been commonly used to evaluate nutrient retention characteristics (Borman et al. 1974). These studies provide information about nutrient flux through ecosystems but offer little information about mechanisms governing nutrient dynamics. In contrast, nutrient spiralling, as described by Webster and Patten (1979), provides a method to evaluate retention and the mechanisms governing it. A nutrient spiral is defined as the distance traveled by a nutrient ion as it completes one cycle from dissolved form to particulate form and back to dissolved form. The distance a nutrient ion travels in dissolved form is called the uptake length and typically accounts for > 90% of spiralling length (Newbold et al. 1983). Uptake length is commonly used instead of spiralling length, because unlike spiralling length, uptake length can be measured without the use of radiotracers. Nutrient spiralling, developed in the late 70's and early 80's, is a relatively new concept. Work on spiralling length (or uptake length) has just begun to allude to possible mechanisms of solute retention and the relative importance of these mechanisms (see Solute Working Group 1990 for a review of concepts and methodology). Recent nutrient retention studies have shown phosphorus retention to be affected by both physical (e.g. temperature, velocity) and biological (e.g. microbial activity, organic matter biomass) factors. However, these studies have yielded conflicting information as to the relative importance of these factors. For example, Gregory (1978) and Elwood et al. (1981) demonstrated that uptake was mostly biotic, while Meyer (1979) found that uptake was determined by physical factors in the streams she studied. This contradiction suggests that streams may range from those driven primarily by biological mechanisms to streams driven almost entirely by physical factors with most streams falling somewhere between these extremes. The relative importance of physical and biological factors may vary spatially and temporally within a stream. This study was designed to systematically identify and examine factors that influence nutrient retention. More specifically, the objectives of this study were: 1) Examine microbial colonization and breakdown characteristics of leaves with different amounts of structural rigidity, under different constrainment techniques, to gain insight into how these characteristics may affect nutrient retention. 2) Use artificial streams to separate and identify factors governing nutrient retention by controlling flow and using different amounts and types of leaf material. 3) Evaluate how land-use practices may alter phosphorus retention mechanisms by comparing results of nutrient releases in natural streams draining undisturbed mixed hardwood watersheds with releases in streams draining disturbed watersheds (i.e. watersheds that had been logged and planted in white pine). / Ph. D.

Excess phosphorus is often identified as a major factor in the eutrophication of wetlands and lakes. Often attributed to agricultural practices, the specific source of a large part of this excess has been difficult to determine. The term "nonpoint" source is often used to broadly describe the inflow along waterways of significant amounts of this essential plant nutrient and other pollution. This research was intended to determine the effectiveness of using cattails (Typha), a common plant along waterways, as indicators of plant available phosphorus in the soil along these waterways. Two sites in the southern part of Michigan's lower peninsula (45°N,84°W) where cattails grew were systematically examined for phosphorus and certain cattail characteristics. Plant and soil data were gathered in a grid-like pattern to determine both the relationship of paired data and their spatial distribution across each site. One set of data was shown to be significant. At one site, the density of cattails is weakly correlated with Phosphorus concentrations. Of particular importance, the spatial distribution of both variables is also noticeably similar at the site. No significant correlation between other data was shown. There is also no apparent similarity in spatial distribution. Though weakly correlated, we were able to support a hypothesis that a reasonable correlation exists between cattail density and plant available phosphorus at one site. The spatial distribution of these traits are also similar suggesting that cattails may, in some cases, be useful as indicators of excess phosphorus, perhaps better defining its source than “nonprint”. / Department of Biology

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.

Lai, Yuk Fo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 169-191). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.iv / Dedication --- p.v / Acknowledgement --- p.vi / Table of contents --- p.viii / List of tables --- p.xii / List of figures --- p.xiii / List of plates --- p.xv / List of symbols and abbreviations --- p.xvi / Chapter Chapter One --- Introduction / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Research background --- p.1 / Chapter 1.2.1 --- Wetlands and water quality --- p.1 / Chapter 1.2.2 --- The role of sediments in eutrophication control --- p.3 / Chapter 1.2.3 --- Wetlands in ecological mitigation --- p.4 / Chapter 1.2.4 --- Previous studies of wetland pollution in Hong Kong --- p.6 / Chapter 1.3 --- Conceptual framework --- p.8 / Chapter 1.4 --- Objectives of the study --- p.12 / Chapter 1.5 --- Significance of study --- p.13 / Chapter 1.6 --- Organization of the thesis --- p.14 / Chapter Chapter Two --- Literature Review / Chapter 2.1 --- Introduction --- p.15 / Chapter 2.2 --- Quantification of phosphorus retention in wetlands --- p.16 / Chapter 2.2.1 --- Input-output concentration approach --- p.16 / Chapter 2.2.2 --- Mass balance approach --- p.18 / Chapter 2.2.3 --- Phosphorus removal efficiency --- p.19 / Chapter 2.3 --- Phosphorus sorption by wetland sediments --- p.20 / Chapter 2.3.1 --- Sorption and its significance --- p.20 / Chapter 2.3.2 --- Phosphorus sorption maxima --- p.22 / Chapter 2.3.3 --- Adsorption-desorption equilibrium --- p.23 / Chapter 2.3.4 --- Phosphorus sorption kinetics --- p.24 / Chapter 2.4 --- Phosphorus exchange across the sediment-water interface --- p.24 / Chapter 2.4.1 --- Phosphorus mobilization and transport mechanisms --- p.25 / Chapter 2.4.2 --- Phosphorus flux from aquatic sediments --- p.26 / Chapter 2.5 --- Phosphorus fractionation in wetland sediments --- p.29 / Chapter 2.5.1 --- Major sediment phosphorus fractions --- p.29 / Chapter 2.5.2 --- Phosphorus fractionation methods --- p.30 / Chapter 2.5.3 --- Relationships between phosphorus fractions and bioavailability . --- p.32 / Chapter 2.6 --- Factors affecting sediment-water phosphorus exchange --- p.33 / Chapter 2.6.1 --- pH --- p.34 / Chapter 2.6.2 --- Redox potential --- p.34 / Chapter 2.6.3 --- Temperature --- p.35 / Chapter 2.6.4 --- Salinity --- p.35 / Chapter 2.6.5 --- Sediment properties --- p.36 / Chapter Chapter Three --- Methodology / Chapter 3.1 --- Overall study approach --- p.38 / Chapter 3.2 --- Geographical setting of Hong Kong --- p.41 / Chapter 3.2.1 --- Climate --- p.42 / Chapter 3.2.2 --- Geology and landform --- p.44 / Chapter 3.2.3 --- Soil --- p.45 / Chapter 3.2.4 --- Vegetation --- p.45 / Chapter 3.3 --- Study sites --- p.46 / Chapter 3.3.1 --- Site selection --- p.46 / Chapter 3.3.2 --- Site description --- p.48 / Chapter 3.3.2.1 --- The Hong Kong Wetland Park --- p.48 / Chapter 3.3.2.2 --- Mai Po Marshes Nature Reserve --- p.50 / Chapter 3.4 --- Sampling strategy --- p.53 / Chapter 3.4.1 --- Sampling locations --- p.53 / Chapter 3.4.2 --- Sampling dates --- p.57 / Chapter 3.4.3 --- Sample collection and treatment --- p.58 / Chapter 3.5 --- Sample analysis --- p.60 / Chapter 3.5.1 --- Analysis of sediment samples --- p.61 / Chapter 3.5.1.1 --- Sediment texture --- p.61 / Chapter 3.5.1.2 --- Sediment pH --- p.61 / Chapter 3.5.1.3 --- Redox potential --- p.61 / Chapter 3.5.1.4 --- Sediment moisture --- p.62 / Chapter 3.5.1.5 --- Organic matter --- p.62 / Chapter 3.5.1.6 --- Total Kjeldahl nitrogen --- p.63 / Chapter 3.5.1.7 --- "Total Fe, Al, and P" --- p.63 / Chapter 3.5.1.8 --- "Oxalate-extractable Fe, Al, and P" --- p.63 / Chapter 3.5.2 --- Analysis of water samples --- p.64 / Chapter 3.5.2.1 --- "Water pH, conductivity, salinity, turbidity, temperature and DO" --- p.64 / Chapter 3.5.2.2 --- Orthophosphate --- p.64 / Chapter 3.5.2.3 --- Total nitrogen and phosphorus --- p.65 / Chapter 3.5.3 --- Determination of phosphorus exchange characteristics --- p.65 / Chapter 3.6 --- Statistical analysis --- p.65 / Chapter Chapter Four --- Phosphorus Fractionation in Wetland Sediments in Hong Kong / Chapter 4.1 --- Introduction --- p.67 / Chapter 4.2 --- Methodology --- p.68 / Chapter 4.2.1 --- Sample collection and analysis --- p.68 / Chapter 4.2.2 --- Phosphorus fractionation --- p.69 / Chapter 4.2.3 --- Statistical analysis --- p.72 / Chapter 4.3 --- Results and discussion --- p.72 / Chapter 4.3.1 --- Physico-chemical properties of sediments --- p.72 / Chapter 4.3.2 --- Physico-chemical properties of overlying water --- p.78 / Chapter 4.3.3 --- Phosphorus fractionation in sediments --- p.82 / Chapter 4.3.3.1 --- Phosphorus fractions in sediments of the Hong Kong Wetland Park --- p.82 / Chapter 4.3.3.2 --- Phosphorus fractions in sediments of the Mai Po Marshes --- p.89 / Chapter 4.3.3.3 --- Phosphorus fractions in relation to mobility and bioavailability --- p.96 / Chapter 4.4 --- Conclusions --- p.100 / Chapter Chapter Five --- Phosphorus Sorption by Wetland Sediments in Hong Kong / Chapter 5.1 --- Introduction --- p.103 / Chapter 5.2 --- Methodology --- p.104 / Chapter 5.2.1 --- Sample collection and analysis --- p.104 / Chapter 5.2.2 --- Batch incubation experiments --- p.105 / Chapter 5.2.3 --- Sorption kinetics --- p.106 / Chapter 5.2.4 --- Effects of selected environmental factors on phosphorus sorption --- p.106 / Chapter 5.2.5 --- Estimation of sorption parameters --- p.107 / Chapter 5.2.6 --- Statistical analysis --- p.109 / Chapter 5.3 --- Results and discussion --- p.109 / Chapter 5.3.1 --- Phosphorus sorption parameters of wetland sediments --- p.109 / Chapter 5.3.1.1 --- Phosphorus adsorption isotherms --- p.109 / Chapter 5.3.1.2 --- The role of sediments in phosphate buffering --- p.116 / Chapter 5.3.1.3 --- Relationships between phosphorus sorption parameters and physico-chemical properties of sediments --- p.121 / Chapter 5.3.2 --- Kinetics of phosphorus adsorption --- p.124 / Chapter 5.3.3 --- Effects of environmental factors on phosphorus sorption --- p.128 / Chapter 5.3.3.1 --- Effects of pH --- p.128 / Chapter 5.3.3.2 --- Effects of salinity --- p.131 / Chapter 5.3.3.3 --- Effects of temperature --- p.133 / Chapter 5.4 --- Conclusions --- p.136 / Chapter Chapter Six --- Phosphorus Flux from Wetland Sediments in Hong Kong / Chapter 6.1 --- Introduction --- p.139 / Chapter 6.2 --- Methodology --- p.140 / Chapter 6.2.1 --- Sample collection and analysis --- p.140 / Chapter 6.2.2 --- Core incubation experiments --- p.141 / Chapter 6.2.3 --- Estimation of phosphorus flux --- p.142 / Chapter 6.2.4 --- Statistical analysis --- p.142 / Chapter 6.3 --- Results and discussion --- p.143 / Chapter 6.3.1 --- Phosphorus flux from wetland sediments --- p.143 / Chapter 6.3.1.1 --- Phosphorus flux from sediments in the Hong Kong Wetland Park --- p.143 / Chapter 6.3.1.2 --- Phosphorus flux from sediments in the Mai Po Marshes --- p.147 / Chapter 6.3.2 --- Effects of redox conditions on sediment phosphorus flux --- p.152 / Chapter 6.4 --- Conclusions --- p.156 / Chapter Chapter Seven --- Conclusion / Chapter 7.1 --- Introduction --- p.159 / Chapter 7.2 --- Summary of major findings --- p.159 / Chapter 7.3 --- Limitations of study --- p.166 / Chapter 7.4 --- Suggestions for future study --- p.166 / References --- p.169

Graduation date: 1994

Call number: LD2668 .T4 1984 G73 / Master of Science