Microbial Bioavailability and Desorption of Aged Organic ContaminantsEPA Grant Number: U915140
Title: Microbial Bioavailability and Desorption of Aged Organic Contaminants
Investigators: Johnson, Stephanie E.
Institution: University of Virginia
EPA Project Officer: Lee, Sonja
Project Period: September 1, 1997 through September 1, 2000
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1997) RFA Text | Recipients Lists
Research Category: Fellowship - Geology , Academic Fellowships , Ecological Indicators/Assessment/Restoration
The objectives of this research project are to: (1) examine the microbial bioavailability and desorption characteristics of aged organic contaminants on model sorbents and soils; and to(2) investigate the effects of microbially produced biosurfactants on the release of these aged contaminants.
Radiolabeled atrazine, phenanthrene, and 2,4-D will be applied to a series of model sorbents and soils and aged for 0, 14, 90, and 365 days. The model sorbents include porous silica and polystyrene beads, using several pore size ranges, representing both hydrophobic and hydrophilic surfaces. An organic-rich soil will be used to test the adequacy of model sorbents to simulate the aging mechanism. Three biosurfactants that enhance dissolution of each of the contaminants when sorbed to soil will be used to examine the impact of biosurfactants on the release of aged contaminants. Ten grams of each contaminant-aged sorbent will be combined with 20 mL of biosurfactant-containing artificial soil water (at three surfactant concentrations and with surfactant-free controls) in Teflon centrifuge tubes under sterile conditions. The centrifuge tubes will be mixed continuously and sampled six times during a twenty-one day period. If biosurfactants are shown capable of enhancing the release of aged contaminants, furtheradditional experiments will be conducted to examine whether a biosurfactant-producing monoculture is capable of causing enhanced release of the aged contaminant, without supplemental additions of surfactant.