Citation:

Ho, K.T.Y. AND J. Quinn. PHYSICAL AND CHEMICAL PARAMETERS OF SEDIMENT EXTRACTION AND FRACTIONATION THAT INFLUENCE TOXICITY AS EVALUATED BY MICROTOX. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/141 (NTIS PB93185882), 1993.

Description:

Several physical and chemical parameters of sediment extraction and fractionation of organic compounds that influence bioassay results were evaluated. ach parameter was evaluated with a photoluminescent bacterial bioassay (Microtox) as an end point. hree solvents (acetonitrile, acetone, and methanol) were studied for their ability to extract toxic organic components from marine sediments. cetone extracted the most toxicity, with no difference between acetonitrile and methanol. wo methods of fractionating sediment extracts (silica-gel-column chromatography [SGCC] and acid-base fractionation) were compared. GCC was more useful because it resulted in a wider range of responses and was faster to perform than acid-base fractionation. icrotox was used to rank four marine sediments with respect to toxicity and to determine if one chemical class (or fraction) was consistently more toxic among different sediments. ith some caveats, Microtox results agreed with general chemical concentration trends and other bioassay results in distinguishing between contaminated and noncontaminated sediments. lthough results indicated there was not a consistently most toxic fraction among sediments, there was a consistently least toxic fraction. he effect of sediment storage time on toxicity was also evaluated. esults indicated that the most stable chemical fraction (containing nonpolar hydrocarbons) did not change toxicologically for 30 weeks, whereas the more chemically active fraction (containing ketones, quinones, and carboxyls) changed as soon as one week.

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