Research Product

This research program was developed with the overall objective of examining toxic substances, especially organophosphorus compounds, in wetland regions and ascertaining fate and effect in situ and in controlled laboratory microcosm systems. Major attention has been given to azinphosmethyl (Guthion), including effect of abiotic and biotic factors on compound stability and behavior under diverse pH and oxidation-reduction conditions as affected by the microbial biomass. Procedures have been developed for processing of anaerobic wetland sediments for pesticide recovery along with formulation of simulation models of anaerobic/aerobic soil and sediment environments to study pesticide degradation. Redox conditions of soils and sediment-water systems have a significant effect on in situ persistence of synthetic organic pesticides. Analyses indicate that chemical and microbiological characteristics of wetland sediments have equally important consequences on mobility and degradation of toxic compounds. The total invertebrate community and leaf litter decomposition of selected backswamp regions has been examined as affected by Guthion and other pesticides. Ash-tupelo litter decomposition was not adversely affected by Guthion. Dissimilar responses of the complex invertebrate biota and its individual taxa to Guthion and other toxic substances demonstrates the importance of a total community analysis in terms of xenobiotic impact. Systems of continuous-flow and static microcosm systems have been developed for quantitative analyses of the effect of selected toxic substances, including Guthion, methyl parathion, and Kepone. Laboratory/field protocol have included formulations of microbial/enzymatic protocols to analyze xenobiotic effect. A data analysis program has been developed to demonstrate significant correlations between in situ observations and microcosm-generated information. Decomposition of ecological significant substrates, such as chitin, is variously affected by different toxic substances as shown in microcosm investigations. Enzymatic tests, i.e., dehydrogenase and phosphatase, and ATP measurements, are sensitive indicators of biotransformation processes. Significant correlations are seen with microbial diversity indices and specific microbial groups, such as filamentous fungi. Factorial analyses of physiochemical and microbial processes and xenobiotic interaction have demonstrated the application of the microcosm as protocol or 'tool' to simulate pristine and impacted in situ ecosystems.