Bioavailability of cyanide in the different environmental compartments

摘要

Vascular plants possess an enzyme system that detoxifies cyanide by converting it to the ammo acid asparagine. Hybrid willows (Salix matsudana KoidzxSalix alba L.) were exposed to cyanide to determine whether willows can transport and metabolize this compound. Pre-rooted trees were grown in different environmental compartments- spiked or irrigated with potassium cyanide at 24.0+ - 0.5 deg C. Cyanide in compartments, in air and in-tissues of plants was analyzed spectrophotometrically. Results from this study indicated that large amounts of applied cyanide was removed from the systems during the presence of willows. Growing compartments of plants have a strong influence on the removal rates of cyanide. Little or no initial cyanide was detected in plant materials. Volatilization of cyanide was not occurring. Mass balance studies showed that applied cyanide was significantly metabolized during transport through willows cuttings. However, there was a clear difference between the metabolism rates of cyanide by willows exposed to different environmental compartments. The highest cyanide metabolism rate was found at the treatment with willows growing in hydroponic solution with a metabolism rate of 2.44 mgCNV (kg.d), followed by willows growing in sand with a value of 1.02 mgCN/(kg.d). The lowest metabolism rate had the willows growing in soils(0.43 mgCN/(kg o d)). In conclusion, transport and metabolism of cyanide in plants is likely and phytoremediation of cyanide is a feasible option for cleaning soils and water contaminated with cyanide.