research project details
Project Title: Bioavailability and toxicity of ionic organic compounds in
estuarine sediments
Investigator(s): William D. Burgos, Richard F. Unz, and Jon D. Chorover
Sponsor: National Science Foundation
Environmental Problem Addressed:
Pollution of estuarine sediments with organic contaminants.
Research Project Objectives:
Objective of this project is to develop a means to predict the sorption, bioavailability, and toxicity of ionic organic compounds (IOCs) in estuarine sediments based on quantitative structure-activity relationships (QSARs), which are scientifically credible mathematical models relating chemical properties to biological activity.
Summary:
Contaminated sediments pose widespread risks to human health and ecological habitats. The sorption of organic contaminants in estuarine sediments is extremely important in determining their bioavailability and toxicity. One approach to understanding contaminant interactions between sediments and sediment biota is to conduct experiments with model systems.
The primary goal of the research is to develop a means to predict the sorption, bioavailability, and toxicity of IOCs in estuarine sediments based on quantitative structure-activity relationships (QSARs). The research will measure the sorption, bioavailability, and toxicity of structurally similar ionic polycyclic aromatic hydrocarbons (PAHs) in synthetic seawater suspensions of humic-coated hematite and kaolinite. The IOCs to be studied will include 1-naphthoic acid, 4-amino-1-naphthoic acid, 4-hydroxy-1-naphthoic acid, 4-methyl-1-naphthoic acid, and 1-napthylacetic acid. These IOCs were selected because they are known to exert a similar mode of toxic action, a prerequisite for analyzing the results based on QSARs.
The sorption characteristics of the IOCs will be measured in short-term batch experiments, and several different humic surface coverages and initial IOC concentrations will be tested. Humic-mineral-IOC suspensions will be inoculated with microorganisms and bioavailability will be measured as test compound removal, metabolite accumulation, O2 utilization, and 14CO2 production over a 60-day incubation period. Pore water will be collected from the humin-mineral-IOC suspensions and used to measure toxicity using a Microtox system.
The research will improve our ability to predict the fate of ionic substituted PAHs in estuarine sediments, estimate the environmental risk posed by these materials, and evaluate remediation strategies.