Influence of hydroxypropyl-beta-cyclodextrin on the biodegradation of C-14-phenanthrene and C-14-hexadecane in soil

Soil was spiked with [9-C-14]phenanthrene and [1-C-14]hexadecane at 50 mg kg(-1) and aged for 1, 25, 50, 100 and 250 d. At each time point, the microcosms were amended with aqueous solutions of cyclodextrin (HP-beta-CD) at a range of concentrations (0-40 mM). Mineralisation assays and aqueous HP-beta-CD extractions were performed to assess the effect of the amendments on microbial degradation. The results showed that amendments had no significant impact on the microbial degradation of either of the C-14-contaminants. Further, HP-beta-CD extractions were correlated with the mineralisation of the target chemicals in each of the soil conditions. It was found that the HP-beta-CD extraction was able to predict mineralisation in soils which had not been amended with cyclodextrin; however, in the soils containing there was no predictive relationship. Under the conditions of this study, the introduction of the HP-beta-CD, HP-beta-CD into soils did not enhance the biodegradation of the organic contaminants. (C) 2009 Elsevier Ltd. All rights reserved.