Effects of Soil Water Content on Biodegradation of Phenanthrene in a Mixture of Organic Contaminants |
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Authors: | Baozhi Liu M Kathy Banks Paul Schwab |
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Institution: | 1. Ch2M HILL, 1766 Sea Lark Lane, Navarre, FL 32566;2. Tel: (850) 939-8300 ext. 37, (850) 939-0035 (Fax), bliu@ch2m.com.;3. School of Civil Engineering, Purdue University, West Lafayette, IN 47907;4. Tel: (765) 496-3424, (765) 496-1107 (Fax), kbanks@ecn.purdue. edu.;5. Department of Agronomy, Purdue University, West Lafayette, IN 47907;6. Tel: (765) 496-3602, (765) 496-2926 (Fax), pschwab@purdue.edu. |
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Abstract: | Phenanthrene biodegradation was investigated at different soil water contents 0.11, 0.22, 0.33, 0.44 g H2O (g soil)?1] to determine the effects of water availability on biodegradation rate. A subsurface horizon of Kennebec silty loam soil was used in this study. 9-14C] phenanthrene was dissolved in a mixture of organic contaminants that consisted of 76% decane, 6% ρ-xylene, 6% phenanthrene, 6% pristane, and 6% naphthalene, and then added to the soil. The highest rate of mineralization, in which 0.23% of the 9-14C] phenanthrene degraded to 14CO2 after 66 days of incubation, was observed at the soil water content of 0.44 g H2O/g dry soil. Most of the 14C remained in the soil as the parent compound or as nonextractable compounds by acetonitrile at the highest water content. Concentrations of nonextractable compounds increased with water content, but residual extractable phenanthrene decreased significantly with increasing water content, which presumably indicates that bio-transformation occurred. The mineralization analysis of radiolabeled 9th carbon in phenanthrene underestimated phenanthrene biodegradation. The strong adsorption and low solubility of phenanthrene contributed to the low mineralization of phenanthrene 9th carbon. The other components were subject to higher biological and abiotic dissipation processes with increasing soil water content. |
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Keywords: | petroleum soil contamination PAHs mineralization soil moisture content |
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