萘和芘在生菜(Lactuca sativa)体内的累积、微区分布及毒性机制OA

In this study,the bioavailability,transport pathways,micro-distribution,and phytoxicity of low molecular weight naphthalene and high molecular weight pyrene in lettuce(Lactuca sativa)were determined using high performance liquid chromatography,enzyme activity assays,and fluorescence microscopy imaging.The results showed that the stems,leaves,and roots of lettuce plants accumulated more pyrene than naphthalene.Exposure to higher concentrations of PAHs led to increased PAH accumulation in the roots,but the amounts of PAHs accumulated in the stems and leaves was independent of the exposure concentration.Both types of PAHs were predominantly concentrated in the root vascular bundles,root cortex tissues,and vascular bundles of stems and leaves.Compared with pyrene,naphthalene exhibited a greater translocation capacity from the roots to the stems and leaves of lettuce because of its lower molecular weight and higher solubility.As the naphthalene concentration increased,antioxidant enzyme activity decreased,the chlorophyll a content increased,and the chlorophyll b content did not change significantly.As the pyrene concentration increased,the contents of both chlorophyll a and b tended to decrease,whereas antioxidant enzyme activity demonstrated a biphasic dose-response pattern characterized by initial induction followed by inhibition.These results indicate that pyrene is more bioavailable than naphthalene.The lettuce plants tended to retain pyrene in the roots,whereas naphthalene was more readily transported to aerial parts.Naphthalene primarily induced a stress response in lettuce characterized by enhanced photosynthesis,with damage to the enzymatic system intensifying as the concentration increased.In contrast,pyrene directly disrupted chloroplast structure and function.The impact of pyrene on the enzymatic system demonstrated a typical dose-effect relationship:low concentrations resulted in increased antioxidant enzyme activity,while high concentrations suppressed their activity.The ecotoxicological effects of PAHs are highly dependent on their physicochemical properties,as these determine how they interact with biological systems.Ecological risk assessments should consider the adaptive capacity of each organism and the contaminant-specific dose-response relationship.