Effects of alfalfa and organic fertilizer on benzo[a]pyrene dissipation in an aged contaminated soil

BACKGROUND: A climate-controlled pot experiment was conducted to investigate the effects of planting alfalfa and applying organic fertilizer on the dissipation of benzoa]pyrene from an aged contaminated agricultural soil. RESULTS: Short-term planting of alfalfa inhibited the dissipation of benzoa]pyrene from the soil by 8.9%, and organic fertilizer enhanced benzoa]pyrene removal from the soil by 11.6% compared with the unplanted and unfertilized treatments, respectively. No significant interaction was observed between alfalfa and organic fertilizer on benzoa]pyrene dissipation. Sterilization completely inhibited the removal of benzoa]pyrene from the soil indicating that its degradation by indigenous microorganisms may have been the main mechanism of dissipation. Furthermore, significant positive relationships were observed between benzoa]pyrene removal and the contents of soil ammonium nitrogen, nitrate nitrogen, and total mineral nitrogen at the end of the experiment, suggesting that competition between plants and microorganisms for nitrogen may have inhibited benzoa]pyrene dissipation in the rhizosphere of alfalfa and the addition of organic fertilizer may facilitate microbial degradation of benzoa]pyrene in the soil.