Date of Award

1996

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Veterinary Physiology, Pharmacology, and Toxicology (Veterinary Medical Sciences)

First Advisor

Steven A. Barker

Abstract

Rapid, generic, and environmentally friendly methods for extraction and detection of the pesticides atrazine, cyanazine, metribuzin, and simazine were developed for use in monitoring the cause of pesticide related or suspect fish kills. Further, environmental hypoxia and elevated temperature were studied as possible contributors to the toxicity of atrazine in channel catfish (Ictalurus punctatus) and as synergistic factors to be considered in investigating fish kill events. Incurred residues from the exposure of catfish to atrazine alone or hypoxia or elevated temperature and atrazine were also analyzed. A commercial enzyme-linked immunoassay (ELISA) was utilized as a screening method for the presence of atrazine in fortified fish tissue with extracts obtained from matrix solid phase dispersion (MSPD). Under conditions for the toxicity of atrazine and hypoxia test, tissue concentrations determined by HPLC in exposed fish were 22.1 ppm in the muscle and 32.8 ppm in the liver under normoxia; under hypoxia, concentrations were 22.4 ppm in the muscle and 35.3 ppm in the liver. In addition, fish exposed to hypoxia and atrazine died sooner than fish exposed to normoxia and atrazine. For the elevated temperature and atrazine toxicity test, tissue concentrations were 17.2 ppm in the muscle and 27.2 ppm in the liver at ambient temperatures. Tissue concentrations were 22.2 ppm in the muscle and 37.7 ppm in the liver at elevated temperature. In addition, fish died sooner under increased temperatures. Further, statistical analysis showed that the combination of hypoxia and atrazine and elevated temperature and atrazine exerted dependent effects in fish deaths. MSPD extraction and detection of triazines by HPLC-UV diode array showed excellent linearity of response, precision (both inter- and intra-assay variation), and recovery over a range of analyte concentrations. The ELISA gave anticipated responses at negative, low, and high concentrations with no matrix interference. Environmental factors of hypoxia and elevated temperature were observed to increase the toxicity of atrazine to channel catfish. Such findings may prove significant in placing the cause or contribution of pesticides to fish kill events.

ISBN

9780591289152

Pages

211

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