中文摘要：

研究植物根系吸收多环芳烃的动力学特征对控制其进入食物链、保障农产品安全有重要意义.因此,本文采用水培方法,研究了小麦根系对萘、菲、芘吸收的动力学机制.结果表明,小麦根系对水培环境中的萘、菲和芘均有明显的吸收和累积作用,且吸收量均随时间延长而增加,整个吸收过程可分为快速吸收和慢速吸收两个阶段.小麦根系对萘、菲和芘的吸收速率快慢表现为芘〉菲〉萘,且萘、菲、芘吸收的动力学曲线可用米氏方程表征,相应的Km值分别为759.30、12.89和3.59μmol·L^-1,即小麦对萘、菲、芘的亲和力大小为芘〉菲〉萘,结果与其Kow值大小顺序一致.小麦根系吸收萘、菲、芘均会导致营养液pH值升高,吸收单个萘、菲、芘分子产生的pH升高幅度表现为芘〉菲〉萘.上述结果显示,萘、芘的根系吸收特征与菲相似.

英文摘要：

Understanding the kinetic characteristics of polycyclic aromatic hydrocarbon （PAH） uptake by plant roots is important in revealing the mechanism of PAH uptake, and further in taking agronomic measures to reduce PAH accumulation in crops for a better food safety. Hydroponic experiments were employed to investigate the uptake of naphthalene, phenanthrene and pyrene （three representatives of PAHs） by wheat roots. Wheat roots can take up the three PAHs from Hoagland nutrient solution and the three PAHs absorbed by roots increase with incubation time. The uptake process consists of two sequential phases, a fast accumulation process and a slow one. The ability of wheat roots to take up the three PAHs is in the order of pyrene〉phenanthrene〉naphthalene. Concentration-dependent uptake of the three PAHs by wheat roots can be described with Michaelis-Menten equation and the Km values for naphthalene, phenanthrene and pyrene are 759.30, 12.89 and 3.59 μmol·L-1, respectively. The affinity of the three PAHs to wheat root carrier proteins is pyrene〉phenanthrene〉naphthalene. The order of the affinity for the three PAHs is consistent with that of the Kow. Solution pH increases due to naphthalene, phenanthrene and pyrene uptake, and the order of increase in pH per molecule of the three PAHs absorbed is pyrene〉phenanthrene〉naphthalene. The trend in pH increase is in good agreement with that in affinity. Therefore, it is concluded that the uptake of naphthalene and pyrene by wheat roots is similar to that of phenanthrene.