Novel Methods for Monitoring Chlorinated Contaminants in Aquatic Environments

Abstract

Chemical exposure assessment is a fundamental component of ecological risk assessment. Without proper tools to determine exposure, final decisions regarding risk must be estimated. In this study, novel methods for improving exposure assessment in aquatic ecosystems were evaluated.

Methods for rapid extraction, detection, and quantification of two dioxin-like compounds in tissue, sediment, and water were developed and validated. Methods were notably sensitive and reproducible. The methods were applied to fish samples with induced ethoxyresorufin-O-deethylase activity. Although the compounds were not detected, this study demonstrated for the first time the analysis of tetrachloroazobenzenes with low ppb method detection limits.

A novel passive sampling device (PSD), a tool used to monitor waterborne concentrations of organic contaminants, consisting of polydimethysiloxane (PDMS) as the polymeric sorption material was developed. Uptake rates were determined for a suite of >50 polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) into PDMS disks in order to investigate the device's potential as an in-situ sampler for hydrophobic organic contaminants. Uptake rates ranged from 0.03 to 0.7 L/g*d. Compounds with log Kow values >4.5 remained in the linear uptake phase, demonstrating the ability of PDMS to function as a time-integrated PSD. Results indicate that PDMS offers great potential to be an effective alternative to conventional sampling and other passive sampling techniques.

In the final phase of this project, PDMS samplers were evaluated as mobile PSD attached to flathead catfish. Also, the potential for using adipose fin clips from catfish as a non-lethal sampling technique to estimate concentrations of PCBs and OCPs in muscle tissues was investigated. Results indicated no practical/physical barriers for attaching mobile PSDs to aquatic organisms. Mobile samplers provided accurate estimates of location specific concentrations of waterborne contaminants that fish were exposed to during the sampling period. Adipose fin concentrations were highly correlated (r2 = 0.77) with those found in the muscle, which requires mortality. This study represents the first time mobile PSDs and adipose fin clips have been used for exposure assessment of organic contaminants.