Phytoremediation and modeling of land contaminated by hydrocarbons

摘要

The use of deep-rooted plants for phytoremediation of contaminated soils has been offered as an alternative to excavation and incineration or landfilling for waste management. Plant root exudates may stimulate microbial activity and thereby enhance biodegradation of recalcitrant compounds by cometabolism. A predictive model has recently been developed for predicting the fate of recalcitrant hydrocarbons in soil. The model requires extensive testing with field data for validation and calibration. The objective of this paper is to test the model using field data from plants grown in contaminated soil. The soil was contaminated with approximately 10 #mu#g kg~(-1) of 2,4,6-trinitrotoluene (TNT), chrysene and 2,2ft, 5,5 ft-tetrabromobiphenyl (PBB). Treatments were either vegetated (Johnsongrass) or fallow (control). Experimental units consisted of polyvinyl chloride (PVC) columns, 0.1 m in diameter x 1.5 m in length packed with the contaminated soil to a bulk density of 1.4 g cm~(-3). Soils were watered to near field capacity twice weekly. Time domain reflectometry was used to monitor soil microbial biomass was measured using the chloroform fumigation method, root density was determined by image analysis, and chemical concentrations in the soil and herbage were performed by immunoassay techniques. After 90 days there was no significant difference in microbial biomass between vegetated and fallow treatments. Soil moisture was significantly lower in the vegetated treatment than in the fallow treatment. No significant differences in chemical loss were observed between the treatments. Approximately 99