DETOXIFICATION OF FLUORENE, PHENANTHRENE, CARBAZOLE AND P-CRESOL IN COLUMNS OF AQUIFER SAND AS STUDIED BY THE MICROTOX ASSAY

摘要

The changing in the toxicity of mixtures of creosote-related compounds during their aerobic biodegradation was studied in columns of saturated aquifer material. The Microtox assay was used to measure the toxicity of phenanthrene, fluorene, carbazole and p-cresol, added individually or in a mix- ture and to evaluate their detoxification during migration through the columns. When tested alone, phe- nanthrene, fluorene and p-cresol, inhibited Vibrio pscheri luminescence emission (15 min ICso= 140, 750, 1500 mu g/L respectively). In contrast, the toxicity of carbazole was minimal. Phenanthrene, fluorene and carbazole, added concomitantly at concentrations varying between 30 and 300 mu g/L, produced between 24.4 and 49.3 inhibition. Comparison with individual toxicity responses suggested antagon- istic interaction between these compounds. The toxicity of the mixture solutions decreased upon pas- sage through the columns since the inhibition caused by the effiuent solutions averaged 6. Additionally, p-cresol (10,000 mu g/L) enhanced the efficiency of detoxification of the column system, the inhibition by the compound mixture decreased from 81.4 (SD = 2.0) to 15.8 (SD = l.8) after hay- ing passed through the first 3.8 cm of the column, and was undetectable at the two other downgradient ports. A comparison of the data of product disappearance and changes in toxicity indicated that detoxi- fication was the result of the disappearance of phenanthrene and p-cresol. However, the persistence of fluorene and/or potential metabolites seemed to have caused some residual toxicity.