Field Validation of General Methodology for Evaluating Narcosis Toxicity using Sediment Profile Imaging, Passive Samplers and Toxicity Testing

This project has the objective of using thin strips of polyethylene as passive samplers to perform in situ evaluations of the bioavailable quantities of hydrophobic organic chemicals (HOCs) in the sediment of several Texas Bays. Further, by quantifying HOCs using two-dimensional gas chromatography (GC×GC) methods, we are determining the contaminants' chemical activities in the sediments and simultaneously use their retention behaviors to deduce their tendencies to bioaccumulate (i.e., toxic doses). To assess the corresponding toxic responses, we have also conducted toxicity tests with sea urchin gametes using polyethylene (PE)-sorbed HOCs and pore water from sediments from the same locations, to differentiate between narcosis effects and other categories of contaminants or confounding factors.

This GC×GC technique has the ability to resolve thousands of individual chemical components from the unresolved complex mixture (UCM) which will facilitate new understandings of the sources, weathering, and toxicity of the UCM hydrocarbons including polycyclic aromatic hydrocarbons (PAHs). By demonstrating the relationship of the integral burden of bioavailable HOCs identified by GC×GC with corresponding observations of toxicity, we will have a new approach for accurately assessing the toxicological contribution of the entire HOC mixture in bedded sediments as opposed to the current approach of using specific PAHs to estimate toxicity.

Real-time views of sediment profiles at the study sites with the aid of the REMOTS® sediment profile imaging camera will be combined with GC×GC analyses of HOCs in passive samplers deployed in situ, and toxicity data. With these data we expect to develop a method to rapidly and accurately establish the boundaries of areas affected by HOCs contamination. This is particularly relevant for the Texas coast, where a variety of activities related to oil extraction, processing and shipping take place.