A Three-Year Field Study Using Plant-Growth-Promoting Rhizobacteria Inoculants to Enhance Phytoremediation of Petroleum-Contaminated Soils

摘要

Through optimal plant growth leading to stimulation of microorganisms capable of contaminant degradation, remediation of total petroleum hydrocarbons (TPHs) is feasible. Our recently developed multiprocess phytoremediation system (MPPS) addresses a drawback of typical phytoremediation operations: insufficient biomass production. The MPPS includes physical manipulation of soils and the use of naturally occurring plant-growth-promoting rhizobacteria (PGPR) to enhance plant growth and to degrade contaminants. The PGPR alleviate high-contaminant stress by lowering plant stress hormone levels, leading to enhanced plant biomass accumulation, especially root biomass. The overall improved plant performance was measured by photosynthetic capacity as well as plant growth. The MPPS has proven successful at remediation of TPHs at sites burdened with heavy petroleum contamination as well as at sites with low petroleum levels. Successful field tests were performed over a period of 3 years in Southern Ontario, at an oil-sludge-contaminated site with initial contaminant level at 150 g/kg TPH. The site has been used for land farming of oil refinery sludge for many years. The soil is mostly contaminated with high-molecular-weight TPH (CCME fraction 3 [C_(16)-C_(33)] and fraction 4 [C_(34)-C_(50)]). Using MPPS, approximately 35% remediation was achieved each year of the three-year trial. Both fraction 3 and fraction 4 were remediated with equal efficiency.