Dissipation of cyanide contaminants in the rhizosphere environment
Abstract
Phytoremediation had been proven to be a cost-effective technology for removing hazardous contaminants from soil. This dissertation research was designed to evaluate the impacts of plant establishment, biodegradation, and plant-microbe interactions on cyanide-contaminated soil. Two cyanogenic plants (Sorghum bicolor and Linum usitatissimum) and one non-cyanogenic plant (Panicum virgatum) were selected for remediation of iron-cyanide (Prussian blue) contaminated soil. The biodegradation of hydrogen cyanide by rhizosphere microorganisms also was assessed. The cyanide degradation ability of cyanogenic plants was anticipated to be significantly higher than non-cyanogenic plants. As shown in results from a greenhouse study, there was an 85% reduction of total cyanide in soil over the 200-day experimental period by two cyanogenic plants. By evaluating the degradation pathway of 14C-Prussian blue in a growth chamber study, it was verified that approximately 50% of the target contaminant was released through the leaves as the radio-labeled carbon dioxide, through the leaves. Rhodococcus sp., Billus sp., Rhizobium sp., Arthrobacter sp., Pseudomonas sp., and Microbacterium sp. were six culturable microorganisms found in the rhizosphere microbial community. The cyanide degradation pathway of Rhodococcus sp., Bacillus sp., and Microbaterium sp. was assessed, and end-products (carbon dioxide and ammonia) were released through cyanide oxidative reactions. Results from this research indicate that phytoremediation of cyanide contaminated soil is a feasible treatment approach.
Degree
Ph.D.
Advisors
Banks, Purdue University.
Subject Area
Environmental engineering
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