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Title: Biodegradation of polycyclic aromatic hydrocarbons in soils co-contaminated with metals
Author: Obuekwe, Ifeyinwa S.
Awarding Body: Lancaster University
Current Institution: Lancaster University
Date of Award: 2012
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Mixtures of polycyclic aromatic hydrocarbons (PARs) and heavy metals are of major concern in contaminated soil. The aim of this project was to investigate the impact of heavy metals and PAHs on microbial activity, concentrating on the mineralisation of PAHs and partitioning of phenanthrene in the presence of metals. Naphthalene and phenanthrene were used as model PAHs and Zn, Cu, Al and Fe were used as model heavy metals. 14C_ Naphthlene and 14C-phenanthrene mineralisation were followed in soil with varying concentrations of Zn, Cu, Al and Fe; a sequential aqueous\solvent extraction scheme was also used to assess the partitioning of phenanthrene in the presence of these metals. Zn and Cu (50 and 100 mg/kg) stimulated (p < 0.05) 14C-naphthalene mineralisation, but had no impact on 14C-phenanthrene mineralisation. Zn (500 and 1000 mg/kg) had no impact on 14C-phenanthrene mineralisation (p > 0.05), but Cu (500 and 1000 mg/kg) significantly reduced (p < 0.05) phenanthrene catabolism, particularly in aged Cu. Zn and Cu mixtures (500 and 1000 mg/kg) inhibited 14C-phenanthrene catabolism. 14C-Glucose mineralisation (maximum rates) and incorporation into the microbial biomass were significantly reduced at higher Zn and Cu concentrations (500 and 1000 mg/kg). Al and Fe (50 and 100 mg/kg) stimulated (p < 0.05) both 14C-naphthalene and phenanthrene mineralisation, however, Al (500 mg/kg) significantly reduced (p < 0.05) mineralisation of both PAHs. Fe (500 mg/kg) stimulated both 14C-naphthalene and phenanthrene mineralisation. Cu and Al (500 mg/kg) significantly increased (p < 0.05) 14C-phenanthrene extractable CaCh and HPCD fractions, this could be because of their great affinity for the organic and mineral soil components. The impact of metals on the biodegradation of PAHs depends on the type and concentrations of the metals, as well as the incubation time. Studies on metal-P AH impact in soil facilitates the assessment of risk, hazard and bioremediation potential at sites contaminated with both contaminants.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available