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COMPARING THE SOLID PHASE AND SALINE EXTRACT MICROTOX(R) ASSAYS FOR TWO PAH CONTAMINATED SOILS
Citation:
Acheson*, C M., Q. Zhou, Y. Shan, G D. Sayles*, AND M. J. Kupferle. COMPARING THE SOLID PHASE AND SALINE EXTRACT MICROTOX(R) ASSAYS FOR TWO PAH CONTAMINATED SOILS. Ward, C.H. (ed.), ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Allen Press, Inc., Lawrence, KS, 23(2):245-251, (2003).
Description:
The performance of remedial treatments is typically evaluated by measuring the concentration of specific chemicals. By adding toxicity bioassays to treatment evaluations, a fuller understanding of treatment performance is obtained. The solid phase Microtox assay is one potentially useful tool in characterizing the toxicity of contaminated soils and sediments.
Two experiments were conducted to evaluate using the solid phase Microtox assay with two PAH contaminated soils. The first experiment, conducted to refine the solid phase assay procedures, evaluated sample holding times, sample replication, and reference toxicant controls. The EC50 of four samples was measured with 8 replicates of each sample. Samples were stored for as long as 2 weeks without showing substantial changes in toxicity. For future studies, three replicates of each sample are recommended as that degree of replication yielded a statistical power of more than 80% in most samples. Phenol was a reliable reference toxicant displaying a 95% confidence interval of 15.6 to 27.9 mg/L.
In a second experiment, the solid phase Microtox assay was compared to saline extract Microtox assays with mixing times ranging from 5 minutes to 16 hours. Two soil samples were used in this comparison. The solid phase assay was more sensitive with EC50s which were 7 to 50 times lower than the extract EC50s. In addition, the saline extract assays displayed results which varied for mixing times of less than 2 hours. Based on these experiments, the solid phase Microtox test has proved to be a useful assay for measuring the toxicity of PAH contaminated soils.