¹Department of Civil Engineering and ²Department of Agronomy, Kansas State University, Manhattan, KS, 66502, 913-532-1573
The presence of vegetation has been demonstrated to increase the biodegradation of several classes of organic compounds. Polycyclic aromatic hydrocarbons (PAHs) are highly recalcitrant and hydrophobic contaminants. Once incorporated into the soil, biodegradation seems to be the most effective means of remediation. Laboratory experiments were conducted to evaluate the mineralization of PAHs (pyrene and phenanthrene) in the rhizosphere due to cometabolism and assess their fate in the rhizosphere of several species of grasses and legumes. The mechanism of cometabolism was tested by adding phenanthrene to soil containing 14C-pyrene. The cometabolic environment induced due to phenanthrene resulted in an increased generation of 14CO2 especially in the rhizosphere soil with organic acids. The dissipation of 14C-phenanthrene in various rhizosphere soils was assessed for mineralization, volatilization and residual 14C in soil. Mineralization was significantly greater in the warm season grasses, sorghum (Sorghum bicolor L.), bermuda grass (Cynodon dactylon L.) and the legume soybean (Glycene max L.) compared to soil from alfalfa (Medicago sativa L.) which did not differ from control soil. It was found that a large portion of the biodegraded 14C-phenanthrene was incorporated into soil organic matter either as microbial biomass or degradation products.
biodegradation, PAH, rhizosphere, cometabolism
This paper is from the Proceedings of the 10th Annual Conference on Hazardous Waste Research 1995, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.