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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Rieselfelder Kairo

Talbant-Kaiser, Tanta/Aegypten 24 July 2001 (has links) (PDF)
No description available.

A Numerical Simulation of HOPs Transport with a Sorption-Desorption Kinematic Model

Lin, Yu-Jen 22 September 2003 (has links)
The transport of health-related organic micropollutans has been a major water quality and environmental issue in the past few decades. Because of their high toxicity, long environmental half-life and high bioaccumulation factors, many of the hydrophobic organic pollutants (HOPs) are listed as priority pollutants in many countries. Although not all of the chemical and physical factors should be considered in the fate of transportation of all chemicals, a simple one-dimensional mathematical model used to simulate all of the factors was conceptually developed (Bobba et al., 1996). In that study, most important parameters needed in the model were empirically fitted. For numerical simulation of the behaviors of pollutants in the environment, it is important to provide a feasible chemical and physical transport mechanism to describe the geo-chemical and geophysical interactions involved in the system. In this study a general two-dimensional hydrodynamic numerical simulation model is developed .This model can readily extend to a three-dimensional one. The model includes all possible physical and chemical factors that might affect the transport of the pollutants. For validation and demonstration purpose, only sorption-desorption between specified dissolved organic material and phase are studied in the present study. The hydrodynamic model is verified by comparing with the reported numerical results. The numerical model then incorporates the sorption-desorption terms and the sediment effects. From the results of the simulation, the sorption-desorption mechanism and sediment scavenge effect are founded to significantly affects the pollutants fate and transport of an outfall discharge.

Development of an integrative sampling device for hydrophilic organic contaminants in aquatic environments

Alvarez, David A. January 1999 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 154-159). Also available on the Internet.

Natural Organic Matter Interactions with CU(II) in groundwater.

Odem, Wilbert Irwin Jr. January 1991 (has links)
The influence of dissolved natural organic matter (NOM) on the transport of Cu(II) in saturated media was investigated in controlled batch and column experiments. Six sources of natural organic matter (two in their ambient solution matrices and four isolated humic substances) were chosen to represent different environments and different humic fractions. 5i02 and a-Al203 comprised the mineral surfaces with which the NOM and Cu(II) interacted. The experiments were conducted at a constant ionic strength and buffer concentration and at pH 6.2 (all sources) and pH 7.5 (two sources). Equilibrium Cu(II) concentrations were monitored with an ion specific electrode and atomic absorption spectrophotometer and NOM was measured as UV absorbance at 254 rim. Adsorbate effect on particle surface charge was evaluated using microelectrophoresis and the effect of molecular weight on NOM breakthrough was determined with ultrafiltration of column influent and effluent. Column studies showed significant variation in NOM breakthrough as a function of source on a mixed bed of SiO₂ and a-Al203. Humic acid from the Suwannee River showed greater adsorption than the fulvic acid from the same source. The presence of Cu(II) resulted in greater retardation of all the NOM sources than in the Cu(II) free systems. Cu(II) transport was slightly facilitated at pH 6.2 by the Orange County NOM and Biscayne aquifer NOM, while the other NOM sources inhibited Cu(II) movement. At pH 7.5 the Orange County and Biscayne Aquifer sources greatly facilitated the transport of Cu(II) in a mixed bed column. The results of this research suggest that the following mechanisms can influence trace metal transport in saturated media: 1) competition of the NOM with the mineral surface for metal complexation; 2) formation of mixed ligand complexes (metal-NOM-mineral surface); 3) complexation of Cu(II) by adsorbed NOM; and 4) metal bridging of NOM to a mineral surface. The results also show that cations commonly found in natural waters ,especially Ca(II) and Mg(II), can influence the interaction of trace metals and NOM with mineral surfaces.

Development of a Primer on Well Water Sampling for Volatile Organic Substances

Wilson, L. Graham, Dworkin, Judith M. 09 1900 (has links)
Research Project Technical Completion Report, Project No. G828-24, Prepared for the U.S. Department of the Interior, September 1984. / / With the growing problem of ground water contamination by volatile organic substances, drinking water sampling programs are being initiated throughout the United States. A need was recognized for a manual on well water sampling that would bridge the gap between highly technical documents and over -simplified reviews. A primer was therefore developed on establishing and implementing a sampling program. Current information was collected by means of both library research and extensive contact with public agency employees and practicing hydrologists. Portions of a sampling program that required explanation included selection of priority wells, proper sampling at the well head, sample preservation and shipment, chain of custody procedures, laboratory selection, quality assurance and data evaluation. Explanation of these steps is intended to help ensure the legal defensibility of any collected data.

The effect of organic compounds on coagulation

Cormier, Barbara Louise, 1942- January 1976 (has links)
No description available.

Organoclays as sorbents for organic contaminants in aqueous and mixed-solvent systems

Nzengung, Valentine Asongu 12 1900 (has links)
No description available.

Enantiomer- and isomer-specific fate of persistent organic pollutants in the environment

Ross, Matthew Stephen Unknown Date
No description available.

The effects of intenive agricultural practice on bacterial populations in two fresh water lakes.

Osborne, Jeanne C. January 1972 (has links)
No description available.

Coupled sorption and transport of nonionic surfactants in natural soils

Chang, Eric Kenneth 05 1900 (has links)
No description available.

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