TP7 Persistent Organic Pollutants
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(ALB-1117-814358) Influence of Urea-N and Plants on the Remediation of Pyrene in Captina Silt Loam.

Alba, O¹, Wolf, D¹, Mattice, J¹, Davis, K¹, Thoma, G², ¹ Department of Crop, Soil, and Environmental Sciences, University of Arkansas., Fayetteville, Arkansas, United States² Department of Chemical Engineering, University of Arkansas., Fayetteville, Arkansas, United States

ABSTRACT- Fertilization has become a common practice when remediating persistent organic compounds in soil. Phytoremediation is a method in which plants, microorganisms in soil and in the rhizosphere, soil amendments, and the application of agronomic techniques interact to enhance contaminant degradation. Soil, water, oxygen, pH, nutrients, and temperature are key components for phytoremediation. We hypothesized that it was possible to improve remediation of pyrene-contaminated soil by adding N fertilizer and growing bermudagrass (Cynodon dactylon L). Captina silt loam contaminated with 0 or 1000 mg pyrene/kg of soil was amended with urea at pyrene-carbon:urea-N + soil inorganic-N (C:N) ratios of 4.5:1, 9:1, 18:1, or unamended that correspond to 211, 106, 53, and 26 mg N/kg soil, respectively. Zero, one, two, or three bermudagrass sprigs were planted per pot and -33 kPa moisture potential was maintained. Pyrene concentrations, polyaromatic hydrocarbon (PAH) degrader microbial numbers, shoot and root parameters, ammonium-N, and nitrate-N levels were measured following the 100-d greenhouse study. The reduction in pyrene concentration ranged from 31% to 88%. With no plants and C:N ratios of 4.5:1, 9:1, 18:1, and unamended, the pyrene remaining was 687, 482, 225, and 123 mg/kg soil respectively. None of the one, two or three plants at any of the C:N ratios were different (p<0.05)with a mean value of 311 mg pyrene/kg soil. Shoot and root biomass were lower in the treatments that received less urea-N. PAH degrading microbial numbers were significantly higher in the pyrene-contaminated soil compared to the control with log10 MPN/g values of 7.69 and 2.74, respectively. This study indicated that addition of urea-N and bermudagrass did not enhance pyrene degradation under the conditions of this study.

Key words: pyrene, phytoremediation, nitrogen, bermudagrass