John S. Fletcher

Professor, Plant Physiology/Phytoremediation

The use of plants to remediate soil and/or sludge contaminated with industrial wastes (phytoremediation) has promise as an inexpensive, ecologically sound means of cleaning up toxic waste sites. Dr. Fletcher The ideal phytoremediation method would be to revegetate contaminated soil/sludge whereby a community of healthy, growing plants would prevent air and water erosion and gradually foster degradation of soil/sludge contaminants. For this to occur, plants must be able to grow and develop normally when rooted in contaminated soil/sludge, and their roots must foster the degradation of soil pollutants.

The major objective of our research is to identify plant species whose roots produce and release chemicals (cometabolites) that selectively foster the growth and activity of bacteria that degrade polyaromatic hydrocarbon (PAH) compounds. Both laboratory experiments and field analyses at a 20 year old revegetated sludge basin are in progress to determine the depth of root growth, PAH degradation, and contaminant uptake under different environmental conditions.

Through these efforts it will be possible to identify certain plant species whose rhizospheres provide an ecological nitch for the survival and activity of PAH- degrading bacteria. Success in this regard will be highly significant to the field of bioremediation, because introduction of the right plant species and use of appropriate plant husbandry practices will provide a stable, sustained environment for the long-term performance of a desirable population of bacteria in the rhizosphere of the chosen plant.

Selected Recent Publications