Environmental transformation, exposure, and effects of pesticide residues
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Develop and use advanced analytical methodology to identify movement of pesticide residues between environmental compartments in relation to bioavailability. Elucidate chemical and biochemical methanisms and pathways of pesticide residue degradation including characterization of degradation products. APPROACH: This lab will develop new immunochemical, supercritical fluid extraction and capillary electrophoresis methods for polar pollutants of environmental importance. The analytes include light-activated insecticides and their breakdown products. Immunochemical, SFE and CE methods minimize the use of organic solvents and thus are environmental compatible. These methods will be basic tools for our next aim. Our efforts will be also given to effects of pesticides on the tropical agroecosystems in Hawaii. We will examine photodegradation methanisms and kinetics of light-activated insecticides in various types of water. We will investigate the fate of light-activated insecticides in Hawaii’s environment. — PROGRESS: Phloxine B and uranine degradation was found to be fast in the Hawaiian environment examined. Phloxine B and uranine are xanthene dyes widely used as coloring additives in drugs and cosmetics and are potential insecticides for fruit fly control. The fate of phloxine B and uranine in coffee fields and a spill site in Hawaii has been studied. Phloxine B and uranine were degraded fast in top soil (0-5 cm) in Hawaii.These dyes appeared to be tightly bound with soil particles. Phloxine B was rapidly photodegraded in water under sunlight and various light sources in the laboratory. Debromination of phloxine B yielded initial photodegradative products leading to further photolysis. A half-life of phloxine B was found to be about one-half hour in water in sunlight. Thephotolysis rates were also influenced by various salts and amines, and sample pH. Photolysis rate of phloxine B in the buffered halogen salt solutions was in order of increase of I-, Br-, Cland F-. Sodium iodideand ammonium iodide photostabilized phloxine B 24 and 27 folds, respectively, when it was compared with the buffer control. The research also develops solvent-free’ analytical methods. Analytical methods are important tools for assessing and ameliorating risks posed by hazardous chemicals. Methods including capillary zone electrophoresis (CZE) and supercritical fluid extraction (SFE) were developed for the analysis of various xanthene dyes in soil, water, and coffee.