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 (14)C-phenanthrene and (14)C-hexadecane biodegradation in the presence of other hydrocarbons in soil using beta- and alpha-cyclodextrin (CD) solutions, respectively. Prediction of the biodegradation of (14)C-phenanthrene using the beta-CD extraction was robust under single, co-contaminant and multiple contaminant conditions (r(2)=0.92, slope of best fit line=0.87, intercept=7.24, n=84). Prediction of (14)C-hexadecane using the alpha-CD extraction was robust under single and co-contaminant conditions (r(2)=0.92, slope of best fit line=0.97, intercept=1.24, n=60); however, the alpha-CD could not accurately predict (14)C-hexadecane biodegradation in the presence of multiple contaminants. The presence of multiple contaminants enhanced (14)C-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.