中文摘要：

通过静态模拟实验,研究了不同浓度的四环素对苦草生理生长以及苦草叶片中叶绿素含量的影响.结果表明,四环素能有效地降低苦草中叶绿素的含量,抑制苦草的生长,20mg·l^-1四环素处理组的生长率只有对照处理的35%,叶绿素a和叶绿素b的含量只有对照组的31%和23%,水体中四环素达到4mg·l^-1水平时,便可明显影响苦草的生理生长.透射电镜分析表明,20mg·l^-1四环素暴露时,苦草叶片细胞中的线粒体和叶绿体出现质壁分离,叶绿体层间结构紊乱等症状,从而影响了苦草细胞的结构功能,导致了对苦草的毒性效应.在四环素暴露组中加入可溶性有机质（DOM）能有效地降低四环素的毒性,4mg·l^-1四环素暴露组中加入的1mg·l^-1DOM便可使苦草的生理生长恢复至对照水平.

英文摘要：

The effect of aqueous tetracycline on the growth, chlorophyll and ultrastructure of Vallisneria natans in the leaves was estimated in the paper, using static simulation experiment. The results showed that the spiked tetracycline could induce the content reduction of chlorophyll in the leaves and consequently inhibit growth of Vallisneria natans. The relative growth rate and contents of chlorophyll decreased with the increase of concentration of spiked tetracycline. In the treatment with 20 mg·l^-1, the relative growth rate was just 35% of that in the control, similarly, the contents of chlorophyll a and chlorophyll b were 31%, 23% of that in the blank respectively. The aqueous tetracycline could significantly affect the growth of Vallisneria natans when the concentration level of tetracycline was up to 4 mg·l^-1, which may cause an adverse effect to the aquatic eco-system.Furthermore, the results indicated that the ultrastructure of the leave cell of Vallisneria natans in 20 mg·l^-1 teratment showed some morohologic changes using transmission electron microscope, compared with the normal leaves. The result showed that the dissolved organic matter in aquatic environment could efficiently reduce the absorption for tetracycline and resultingly alleviate the toxic effect induced by tetracycline.