Assessment of bioavailability limitations during slurry biodegradation of petroleum hydrocarbons in aged soils

• Published in: Environmental toxicology and chemistry 2003-12, Vol.22 (12), p.2853-2860
• Main Authors: Huesemann, Michael H., Hausmann, Tom S., Fortman, Tim J.
• Format: Article
• Language: English
• Subjects: 02 PETROLEUM; Alkanes; Alkanes - metabolism; Alkanes - pharmacokinetics; BIODEGRADATION; Biodegradation of pollutants; Biodegradation, Environmental; Biological and medical sciences; Biological Availability; BIOREMEDIATION; Biotechnology; CARBON; DESORPTION; Environment and pollution; Fundamental and applied biological sciences. Psychology; Hydrocarbon biodegradation; HYDROCARBON BIODEGRADATION, POLYNUCLEAR AROMATIC HYDROCARBONS, MASS-TRANSFER LIMITATIONS; HYDROCARBONS; Industrial applications and implications. Economical aspects; KINETICS; MASS TRANSFER; Mass-transfer rate limitation; Microbial factors; MICROORGANISMS; ORGANIC MATTER; PETROLEUM; POLYCYCLIC AROMATIC HYDROCARBONS; Polycyclic Aromatic Hydrocarbons - metabolism; Polycyclic Aromatic Hydrocarbons - pharmacokinetics; Polynuclear aromatic hydrocarbons; Soil Pollutants - metabolism; Soil Pollutants - pharmacokinetics; SOILS; SUBSTRATES
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1897/02-611

In an effort to determine whether bioavailability limitations are responsible for the slow or incomplete hydrocarbon biodegradation in aged soils, both the rate of desorption (rdes) and biodegradation (rbio) was measured for n‐alkanes and polynuclear aromatic hydrocarbons (PAHs) at different times during the slurry biotreatment of six different soils. While all n‐alkanes were biodegraded to various degrees depending on their respective carbon number and the soil organic matter content, none of them were desorbed to a significant extent, indicating that these saturated hydrocarbons do not need to be transferred from the soil particles into the aqueous phase in order to be metabolized by microorganisms. Most two‐ and three‐ring PAHs biodegraded as fast as they were desorbed (rbio = rdes); that is, desorption rates controlled biodegradation rates. By contrast, the biodegradation kinetics of four‐, five‐, and six‐ring PAHs was limited by microbial factors during the initial phase (rbio < rdes) while becoming mass‐transfer rate limited during the final phase of bioremediation treatment (rbio = rdes). Whenever PAH biodegradation stalled or did not occur at all (rbio = 0), it was never due to bioavailability limitations (rdes ≫ 0) but was more likely caused by microbial factors, such as the absence of specific PAH degraders or cometabolic substrates. Consequently, PAHs that are found to be microbially recalcitrant in aged soils may not be so because of limited bioavailability and thus could pose a greater risk to the environment than previously thought.