Influence of biochar and compost on phytoremediation of oil-contaminated soil

ABSTRACT

The use of pyrolyzed carbon, biochar, as a soil amendment is of potential interest for improving phytoremediation of soil that has been contaminated by petroleum hydrocarbons. To examine this question, the research reported here compared the effects of biochar, plants (mesquite tree seedlings), compost and combinations of these treatments on the rate of biodegradation of oil in a contaminated soil and the population size of oil-degrading bacteria. The presence of mesquite plants significantly enhanced oil degradation in all treatments except when biochar was used as the sole amendment without compost. The greatest extent of oil degradation was achieved in soil planted with mesquite and amended with compost (44% of the light hydrocarbon fraction). Most probable number assays showed that biochar generally reduced the population size of the oil-degrading community. The results of this study suggest that biochar addition to petroleum-contaminated soils does not improve the rate of bioremediation. In contrast, the use of plants and compost additions to soil are confirmed as important bioremediation technologies.

KEYWORDS:

• bioremediation
• mesquite
• microbial ecology
• petroleum hydrocarbon
• soil pollution

Acknowledgments

The authors would like to thank Dr. Karin Lemkau for her advice on analyzing oil by GC-FID, Dr. Alejandro Alarcón Z. (Universidad de Granma, Cuba) for his contribution to the greenhouse work, Dr. Blanca López (CIBNOR) for her assistance in statistical analysis, and Amilcar Santos for his assistance with the chemical and molecular analyses portions of the project.

Additional information

Funding

This work was supported by the University of California Institute for Mexico and the United States (UC-MEXUS) under UCMEXUS-CONACYT Grant: CN-11-597.