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SEDIMENT TOXICITY IDENTIFICATION AND EVALUATIONS: NEW TEST METHODS. WHAT'S BEEN DONE? WHERE ARE WE GOING?
Citation:
Ho, K T., R M. Burgess, A KuhnHines, M C. Pelletier, M G. Cantwell, J R. Serbst, AND R Tien. SEDIMENT TOXICITY IDENTIFICATION AND EVALUATIONS: NEW TEST METHODS. WHAT'S BEEN DONE? WHERE ARE WE GOING? Presented at North Atlantic Chapter of the Society of Environmental Toxicology and Chemistry, Newport, RI, April 14-15, 2000.
Description:
Toxic sediments pose a risk to aquatic life, human health and wildlife throughout the world. There is an overwhelming amount of evidence that demonstrates chemicals in sediments are responsible for toxicological and ecological effects. The ability to identify the class or specific chemical responsible for toxicity of contaminated sediments is the objective of sediment Toxicity Identification and Evaluation (TIE) methods. These methods are useful in a variety of contexts. Once a toxicant is identified, it can be linked to a discharger and steps can be taken to prevent further discharge of the toxicant. The identification of specific classes of compounds may also be helpful in designing effective sediment remediation schemes or reasonable options for disposal of sediments. Finally, knowledge of the causes of toxicity which drive ecological changes such as community structure can be useful in performing ecological risk assessments. Researchers have performed TIEs on sediment porewaters since the early 1990's. Summary of the current TIE data indicates that usually more than one stressor contributes to sediment toxicity. In marine waters, ammonia and organics are the major causes of toxicity; however, in freshwater sediments, a variety of stressors cause acute toxicity. Phase I whole sediment TIE method development is nearing completion. Whole sediment methods include use of Ulva lactuca or zeolite for removal of ammonia, cationic resins for removal of metals, and powdered coconut charcoal for removal of organics. Method development is still underway for Phase II --identification of organics using powdered coconut charcoal. Finally, in conjunction with method development for whole sediment TIEs we developed smaller whole sediment test chambers (20 g sediment, 60 ml of overlying water) and shorter testing periods (96 h). This smaller, faster experimental design is a good predictor of toxicity in the larger, standard 10 day test.