TP6 Sediment Sampling and Analysis, Including Elutriate and Porewater Techniques
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(WAU-1115-996451) Role of grain size on bioavailability of sediment-bound contaminants in Corpus Christi Bay, Texas.

Wauhob, T¹, Nipper, M¹, ¹ Texas A & M University-Corpus Christi, Center for Coastal Studies, Corpus Christi, Texas, USA

ABSTRACT- Contaminants in marine sediments are expected to be more or less bioavailable according to a range of factors. However, several natural factors that affect bioavailability of contaminants remain relatively unexplored. In the present study, the relationship of porewater toxicity from homogenized sediment samples to toxicity at the sediment-water interface (SWI) of unhomogenized sediment samples is compared between a sandy sediment and a fine grained sediment in Corpus Christi Bay, Texas. A chemical analysis is conducted on the bulk sediment as well as pore water to screen for different categories of contaminants, including metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and chlorinated pesticides. This data is used to help explain relative toxicities between the different grain size samples. Toxicity tests are conducted with the copepod, Schizopera knabeni, and the sea urchin, Arbacia punctulata. Survival and nauplii hatching success are measured by copepod tests while the endpoints of fertilization and embryological development are employed for sea urchins. Pore water is collected by pneumatic extraction and run by established protocols. The SWI method is a relatively novel method and underwent some revisions for the present study. Toxicity results are compared to positive and negative controls, i.e., a reference toxicant (sodium dodecyl sulfate) and clean reference sites of similar grain size. Relative toxicities between sandy and fine grain sediments as well as the resulting implications of toxicant partitioning are discussed.

Key words: Bioavailability, Grain size, Porewater toxicity, Sediment-water interface