氰化物污染的植物修复可行性研究

摘要

氰化物是目前世界范围内最常使用的提取黄金和白银等贵重金属的沥滤剂,其对自然生态环境的污染和破坏以及对人畜和其它生物的毒性作用是众所周知的.本试验用一自行设计的生物反应器来观察黄豆(Glycine max(L)Merr.)和玉米(Zea mays L.)对氰化物污染土壤的原位修复的可能性.室温条件下(23.0～26.0 0C),低浓度的氰化物污染液对(≤45.5 CN mg·L-1)二种测试植物的生长没有产生任何毒性作用;而在高浓度的氰化物试验组(≥91.0 CNmg·L-1),二种测试植物的生长都出现了明显的滞长现象(生长率下降大于10%),但没有观察到其它毒性反应.同时二种测试植物的叶片细胞用来测定植物细胞线粒体中的氰丙氨酸合成酶(β-cyanoalanine synthase)转化氰化物的潜力.实验是在一封闭的玻璃器皿(100 mL)中进行的(100 mL的氰化钾溶液中加入1.5 g(鲜重)植物的叶片,氰化钾溶液的浓度大约1.0 CN mg·L-1).在为期28 h的时间内,水溶液中超过90%的氰化物被植物的叶片去除;黄豆和玉米的的叶片细胞对氰化物去除率分别测定为4.43 mg CN·kg-1(鲜重)·h-1和3.42 mg CN·kg-1(鲜重)·h-1.本实验结果表明,植物对氰化物污染的土壤原位修复方法是一种可行的和有效的选择.%Cyanide is a high-volume production chemical and the most commonly used leaching reagant for gold and silver extraction. Its environmental behavior and fate is of significant concern because of its high toxicity. This paper presents an investigation of the feasibility of phytoremediation as an in- situ technique to treat cyanide-contaminated soil. Corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) were used. Results from this tests indicated that low dose of cyanide (≤45.5 CN detectable effects under room temperature (23.0～26.0℃). Significant reduction in the plant growth rates (≥10 %) was found at high cyanide concentration in the irrigation water (≥91.0 CN mg·L-1) used. The potential of detached leaves to remove cyanide was also investigated. Excised plant leaves (1.5 g fresh weight) were kept in a glass vessel with with 100 mL spiked aqueous solution (deionized oxygen-saturated water) at 23.5 ℃ for 28 h. The disappearance of cyanide from the aqueous solution was tracked photometrically. More than 90 % cyanide in the aqueous solution was removed by plant materials over a 28-h exposure period. The cyanide removal capacity was determined to be 4.43 and 3.42 mg CN · kg fresh weight-1·hour-1 for soybean and corn, respectively. Resutls from this investigation indicated that plants and plant materials were all found to be able to efficiently remove cyanide from the contaminated medium through their internal enzyme systems. In conclusion, cyanide elimination with plants seems to be a feasible option for cleaning soils contaminated with cyanide or gold and silver mine waste and wastewater.