Pyrene mineralization capacity increases with compost maturity.

Area of Science:

• Environmental Science
• Soil Science
• Bioremediation

Background:

• Soil contamination by polycyclic aromatic hydrocarbons (PAHs) is a significant environmental concern.
• Composting is a potential method for soil remediation, but its effects on specific contaminant degradation vary.
• Understanding the impact of composting on the mineralization of different PAHs is crucial for effective soil management.

Purpose of the Study:

• To investigate the effects of soil composting and compost addition on the mineralization of n-hexadecane, pyrene, and benzo(a)pyrene.
• To determine the influence of composting duration and stage on PAH degradation rates.
• To identify microbial agents responsible for enhanced pyrene mineralization.

Main Methods:

• Soil samples (contaminated and clean) were composted with organic matter (maple leaves and alfalfa).
• Composted soil from various stages was spiked with radiolabeled and non-labeled n-hexadecane, pyrene, or benzo(a)pyrene.
• Mineralization was monitored in aerated microcosms at different temperatures.

Main Results:

• Composting or compost addition had no significant effect on n-alkane or benzo(a)pyrene mineralization.
• Pyrene mineralization rate increased significantly with the duration of soil composting.
• Optimal pyrene mineralization (over 60% in 20 days) occurred with composted soil from the curing stage.
• Thermophiles and fungi were not identified as the primary agents of pyrene mineralization.

Conclusions:

• Soil composting duration is a critical factor for enhancing pyrene biodegradation.
• The curing stage of composted soil is most effective for pyrene mineralization.
• Composting does not universally enhance the degradation of all organic contaminants in soil.