Chemometric assessment of enhanced bioremediation of oil contaminated soils

Bioremediation is a promising technique for reclamation of oil polluted soils. In this study, six
methods for enhancing bioremediation were tested on oil contaminated soils from three refinery areas in Iran
(Isfa- han, Arak, and Tehran). The methods included bacterial enrichment, planting, and addition of
nitrogen and phosphorous, molasses, hydrogen peroxide, and a surfactant (Tween 80). Total petroleum
hydro- carbon (TPH) concentrations and CHEMometric analysis of Selected Ion Chromatograms (SIC)
termed CHEMSIC method of petroleum biomarkers including terpanes, regular, diaromatic and
triaromatic ster- anes were used for determining the level and type of hydrocarbon contamination.
The same methods were used to study oil weathering of 2 to 6 ring polycyclic aromatic compounds
(PACs). Results demon- strated that bacterial enrichment and addition of nutrients were most
efficient with 50% to 62% removal of TPH. Furthermore, the CHEMSIC results demonstrated that the
bacterial enrichment was more effi- cient in degradation of n-alkanes and low molecular weight PACs
as well as alkylated PACs (e.g. C3 –C4 naphthalenes, C2 phenanthrenes and C2 –C3
dibenzothiophenes), while nutrient addition led to a larger relative removal of isoprenoids (e.g.
norpristane, pristane and phytane). It is concluded that the CHEMSIC
method is a valuable tool for assessing bioremediation efficiency.