不同作物根系多环芳烃吸收特征差异的比较研究

Characterization Comparison of Polycyclic Aromatic Hydrocarbon Uptake by Roots of Different Crops

为选育不/少或超量吸收多环芳烃(PAHs)的植物品种进而进行农产品的安全生产和PAHs污染环境的植物修复,以菲为PAHs的代表物,比较了水培条件下3种常见农作物(大豆、小麦、胡萝卜)根系吸收菲的动力学特征差异.结果表明,3种作物根系对水培液中的菲有明显的吸收和累积作用,且菲的吸收量随时间延长而增加,整个吸收过程可分为快速吸收和慢速吸收2个阶段;3种作物根系菲吸收能力的大小为大豆>胡萝卜>小麦;作物根系吸收菲量与吸收时间的关系可以用Elovich方程拟合,大豆、胡萝卜和小麦根系菲吸收速率常数分别为4.31、4.10和2.84 mg.(kg.h)-1;作物根系菲吸收的动力学曲线可用米氏方程表征,大豆、胡萝卜和小麦根系菲的Km值分别为0.117、0.124和0.540 mg.L-1;根系菲吸收会导致营养液pH升高,pH升高的趋势和吸收速率常数k与Km值相对应,且与3种作物根系吸收能力的大小一致.因此可用根系吸收速率常数k、米氏常数Km值和水培液pH的变化表征作物根系吸收PAHs的能力差异,且从受影响因素的多寡角度考虑,吸收速率常数k和米氏常数Km较pH变化更适合.

It is important to investigate the differences in polycyclic aromatic hydrocarbon （PAH） uptake by roots of different crops for selecting and breeding less or excess uptake species of PAHs by genetic engineering, and further yielding safe production and phytoremediating the soil or water contaminated with PAHs. Hydroponic experiments were performed to study characterization comparison of phenanthrene （a representative of PAHs） uptake by soybean, wheat and carrot roots. Soybean, carrot and wheat roots can take up phenanthrene from Hoagland nutrient solution and the phenanthrene absorbed by roots increases with incubation time. The uptake process consists of two sequential phases： a fast accumulation process followed by a slow one. The capability to take up phenanthrene for the three crops can be arranged as soybean 〉 carrot 〉 wheat. The relationship between the phenanthrene absorbed and time fits Elovich equation well. Uptake rate constants for soybean, carrot and wheat roots are 4.31, 4. 10 and 2.84 mg. （ kg. h） -l , respectively. Concentration-dependent uptake of phenanthrene by roots of soybean, carrot and wheat can be described with Michaelis- Menten equation and the Km values for soybean, carrot and wheat are 0. 117, 0. 124 and 0. 540 mg.L-1. Hydroponic solution pH increases due to phenanthrene uptake and the trend in pH increase significantly correlates with those in uptake rate constant and Km value. In addition, the orders of uptake rate constant, Km value and pH increase for soybean, carrot and wheat are the same as that of uptake capability. Therefore, it is concluded that uptake rate constant, Km value and pH increase can be employed as indicators for the capability to take up PAHs by crop roots, and uptake rate constant and Km value are better indicators than pH increase because of less affectin~ factors.