Prediction of microbial accessibility of carbon-14-phenanthrene in soil in the presence of pyrene or benzo[a]pyrene using an aqueous cyclodextrin extraction technique

Traditionally, solvent extractions are routinely used in the assessment of contaminated land. However, vigorous solvent extractions only give total concentrations rather than that relating to the bioaccessible fraction. Recently, less harsh, aqueous-based extraction methods have been shown to be a better estimate of the microbial degradation of polycyclic aromatic hydrocarbons (PAHs). The aqueous-based hydroxypropyl-beta-cyclodextrin (HPCD) extraction, technique was tested using C-14-PAHs in soils and compared, against indigenous microbial mineralization (a measure of bioaccessibility) of C-14-phenanthrene in the presence of pyrene or benzo[a]pyrene (B[a]P),over a range of concentrations (0, 5, 10, or 50 mg kg(-1)), and aged for 0, 25, 50, and 100 d in four soils. At each time point, the total loss, extractability, and, mineralization of C-14-phenanthrene was measured in each of the soils. The presence of the other PAHs had little effect on the behavior of C-14-phenanthrene in any of the soils. Comparisons. between the amounts of C-14-phenanthrene extracted using, HPCD and mineralized were made and showed that there was a correlation (1:1). This study demonstrates that HPCD extraction is able to predict the microbial accessibility fraction of (14) C-phenanthrene in the presence of other PAHs in a range, of soils, further supporting the applicability of this technique.