苏柳172和垂柳对Pb的吸收动力学特性及有机酸的影响

UPTAKE OF LEAD BY SALIX JIANGSUENSIS CL J-172 AND SALIX BABYLONICA LINN AND THE INFLUENCE OF ORGANIC ACIDS

采用溶液培养的方法研究了苏柳172(Salix jiangsuensis CL‘J172’)和垂柳(Salix babylonica Linn)的Pb吸收动力学、Pb在根区的分布以及低分子量有机酸对Pb吸收的影响.结果表明,在溶液Pb浓度为0.25—100μmo.lL-1时,两种柳树对Pb的吸收动力学都呈非饱和曲线,积累量随浓度的增大及时间的延长而增加.垂柳根的吸收力α(Vmax/km)值0.99 L.g-.1h-1明显高于苏柳172根的α值0.16 L.g-.1h-1,在溶液中Pb浓度为20μmol.L-1时,垂柳的Pb吸收量在120 min和48 h时均为苏柳172的1.4倍,因此,垂柳对Pb的吸收积累能力强于苏柳172.柳树根尖区的Pb含量远远大于成熟区,根尖区是吸收Pb最活跃的区域.一定摩尔浓度配比的乙酸和苹果酸可以促进Pb的吸收,苹果酸和乙酸与Pb摩尔浓度配比为10∶1时,苏柳172的Pb吸收量是对照的2.39倍和1.54倍,苹果酸和乙酸与Pb摩尔浓度配比为5∶1时,垂柳的Pb吸收量是对照的1.48和1.34倍.施加高浓度苹果酸未促进铅向地上部的运输.

The uptake of lead by two willow species,Salix jiangsuensis CL＇J172＇ and Salix babylonica Linn,and the effect of acetic and malic acids on lead accumulation were studied under hydroponics.The results suggest that the net concentration-dependent uptake influx of Pb in both willows were chatacterized by Michaelis-Menten type nonsaturating kinetic curves.The uptake amount of lead by the roots of both willow species increased with lead concentration and time.The content of Pb in the root cap was significantly higher than that in the root mature zone which suggest that the root cap was more active in Pb upake.The addition of acetic and malic acids enhanced the uptake of Pb in salix roots.Lead content in the roots of Salix jiangsuensis CL＇J172＇ was 2.39 and 1.54 times higher than that of the control respectively when the concentration ratio of organic acid to Pb was 10∶1.The content of Pb in Salix babylonica was 1.48 and 1.34 times higher in comparison with control when the concentration ratio was 5∶1.The content of Pb was not enhanced from root to shoot and leaf with high malic acid concentration treatment.