Predicting the biodegradation of target hydrocarbons in the presence of mixed contaminants in soil

The aim of this study was to investigate the prediction of ¹⁴C-phenanthrene and ¹⁴C-hexadecane biodegradation in the presence of other hydrocarbons in soil using β- and α-cyclodextrin (CD) solutions, respectively. Prediction of the biodegradation of ¹⁴C-phenanthrene using the β-CD extraction was robust under single, co-contaminant and multiple contaminant conditions (r² = 0.92, slope of best fit line = 0.87, intercept = 7.24, n = 84). Prediction of ¹⁴C-hexadecane using the α-CD extraction was robust under single and co-contaminant conditions (r² = 0.92, slope of best fit line = 0.97, intercept = 1.24, n = 60); however, the α-CD could not accurately predict ¹⁴C-hexadecane biodegradation in the presence of multiple contaminants. The presence of multiple contaminants enhanced ¹⁴C-hexadecane mineralisation, but did not enhance extractability. The results from this study provide further evidence for the application of HPCD extractions for the measurement of microbial accessibility in soil.