植物对水中菲和芘的吸收

Uptake of phenanthrene and pyrene by ryegrass from water

以菲和芘为多环芳烃（PAHs）代表物,采用水培体系研究了黑麦草（Lolium multiflorum Lam）对水中PAHs的吸收作用,重点研究了植物吸收菲和芘的时间动态.水中菲和芘起始浓度分别为1.00mg/L和0.12mg/L.0～288h内,黑麦草根和茎叶中菲和芘含量均先快速增加而后降低,积累量不断增大,植物根系和茎叶富集系数则先快速升高而后趋于稳定.茎叶中菲和芘含量、茎叶对菲和芘的富集系数比根低1～3数量级,积累量也明显小于根系.黑麦草根系对水中芘有更强的富集能力,其根系富集系数比菲大85%～179%;而其茎叶对菲的富集作用则略强.菲和芘在植物体内有明显的传导作用.0～288h,传导系数（TF）先显著升高而后趋于恒定;但实验条件下,菲和芘的TF值均很小,分别不高于0.031和0.009,且芘的TF值明显小于菲,表明供试植物对芘的传导能力更弱.

Polycyclic aromatic hydrocarbons （PAHs） are by-products from the incomplete combustion or pyrolysis of organic materials. Many PAHs and their derivatives are strongly potent carcinogens and/or mutagens, and belong to a chemical class targeted by the US Environmental Protection Agency （EPA）. PAHs have been found with high concentrations in soil and water environment, posing great threats to human health all over the world. Uptake by plants from the surrounding soil and water is an important step for the transfer of organic toxic contaminants into food chain and web. Clearly, understanding of how plants take up organic contaminants such as PAHs from the environment will have considerable benefits for risk assessment purposes. However, there is still limited information available on plant uptake of PAHs from soil and water in the last decades. As a result, the distribution of PAHs in soil/water-plant systems heretofore needs to be elucidated. In this work, the uptake of phenanthrene and pyrene, as representatives of PAHs, by ryegrass （ Lolium multiflorum Lam） from culture solution was investigated using a greenhouse study. The initial concentrations of phennathrene and pyrene in aqueous solution were 1.00 and 0.12 mg/L. It was observed that the concentrations of these PAHs in ryegrass firstly increased and decreased thereafter in the uptake duration of 0 - 288 h. While the accumulated amounts of tested PAHs by ryegrass roots and shoots increased straightly, and root and shoot concentration factors of phenanthrene and pyrene initially increased sharply and a steady state was observed thereafter in 0 - 288 h. It was notable that shoot concentrations, accumulated amounts, and shoot concentration factors of phenanthrene or pyrene were generally much lower than root. In addition, root concentration factors of pyrene were generally 85%-179% higher than those of phenanthrene. By contrast, shoot concentration factors of pyrene were smaller than those of phenanthrene. The translocation of phenanthrene and pyrene from root to shoot was observed in that duration.The translocation factors （TF） were calculated. TF values increased firstly and kept approximately steady thereafter in 0 - 288 h. However, TF values of phenanthrene and pyrene were small （less than 0.031 and 0.009, respectively）, indicating that the translocation of these compounds from root to shoot in ryegrass was dramatically restricted. In addition, since the Kow value of pyrene was bigger than that of phenanthrene, a larger portion of pyrene would be partitioned into plant tissues particularly plant lipid parts, resulting in the smaller TF values of pyrene than those of phenanthrenc. Results of this greenhouse study would provide some insight into the uptake of hydrophobic organic chemicals hy plants, and would be valuahle for food security and environment protection.