Effect of Temperature on the Uptake and Metabolism of Cyanide by Weeping Willows

Abstract

Plants’ uptake and metabolism of cyanide in response to changes in temperature was investigated. Pre-rooted weeping willows (Salix babylonica L.) were exposed to hydroponic solution spiked with potassium cyanide for 2–3 d. Ten different temperatures were used, ranging from 11°C to 32°C. Cyanide in water, plant tissue, and air was analyzed spectrophotometrically. The results revealed that significant amounts of the applied cyanide were removed from the aqueous solutions in the presence of plants. Small amounts of free cyanide were detected in plant materials in all treatments, but there was no clear trend that showed an increase or decrease in the accumulation in plant material with temperature. The highest cyanide metabolism rate for weeping willows was found at 32°C with a value of 2.78 mg CN/(kg·d), whereas the lowest value was 1.20 mg CN/(kg·d) at 11°C. The temperature coefficient, Q₁₀, which is the ratio of metabolism rates at a 10°C difference, was determined for weeping willows to be 1.46. In conclusion, changes in temperature have a substantial influence on the uptake and metabolism of cyanide by plants, but cyanide accumulation does not increase with temperature.

KEY WORDS:

• cyanide
• metabolism
• phytoremediation
• temperature
• weeping willows

ACKNOWLEDGEMENTS

This work was supported by Hunan Agricultural University (grant 03YJ05). The authors thank Yawen Tang and Yongmiao Yang for their engaged help.