Biodegradation of phenanthrene in river sediment

Area of Science:

• Environmental microbiology
• Bioremediation of polycyclic aromatic hydrocarbons (PAHs)

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants found in river sediments.
• Understanding the biodegradation potential of PAHs is crucial for assessing environmental risks and developing remediation strategies.

Purpose of the Study:

• To investigate the aerobic biodegradation potential of phenanthrene in river sediment.
• To determine the factors influencing phenanthrene biodegradation rates and identify optimal conditions.

Main Methods:

• Laboratory incubation of phenanthrene in river sediment samples collected from the Keelung River, Taiwan.
• Measurement of biodegradation rate constants (k1) and half-lives (t1/2) under varying phenanthrene concentrations and environmental conditions.
• Assessment of the impact of carbon sources and nutrient additions (ammonium, sulfate, phosphate) on biodegradation.

Main Results:

• Phenanthrene biodegradation rates varied significantly across different sediment samples, with higher rates observed in the absence of sediment.
• Optimal biodegradation occurred at 30°C and pH 7.0, with reduced rates at higher phenanthrene concentrations (5-100 µg/g).
• Nutrient addition (ammonium, sulfate, phosphate) significantly enhanced biodegradation, while carbon sources had minimal impact. Phenanthrene presence also boosted the degradation of anthracene, fluorene, and pyrene.

Conclusions:

• River sediment possesses aerobic biodegradation potential for phenanthrene, influenced by concentration, temperature, and pH.
• Nutrient availability is a key factor for enhancing phenanthrene biodegradation in riverine environments.
• Phenanthrene can co-metabolize other PAHs, suggesting potential for combined remediation strategies, but does not induce benzo[a]pyrene degradation.