Hg、Cd及其复合污染对浮萍叶片的毒害研究

The Study on Effect of Hg,Cd and Their Combined Pollution in Leaves of Lemna minor L.

研究了不同浓度Hg、Cd及其复合污染对浮萍（Lemna minor L.）叶片生理生化以及超微结构的毒害影响.经观察分析,培养4d后各处理组均呈现出不同程度的受害症状.随处理浓度的递增,叶绿素含量以及可溶性蛋白含量明显下降;抗氧化酶系统活性及脯氨酸含量均表现出-显著抗性峰,而后下降.通过电镜观察发现、叶绿体膨胀,外膜破裂,基粒片层垛叠混乱;线粒体脊突膨胀,呈现凌乱状态甚至空泡状残体;细胞核变形,核膜内陷,染色质凝集,呈无序状态甚至解体.结果表明:Cd对浮萍叶细胞的毒件比Hg大.Hg、Cd复合污染呈现明显的协同作用,加强了对叶细胞的伤害.Hg对于浮萍叶片的致死浓度在5～7mg/L之间;Cd的致死浓度在2.5～5mg/L之间;Hg+Cd的致死浓度在1mg/LHg+1mg/LCd～2.5mg/L Hg+2.5mg/LCd之间.

The paper dealed with the effect of Hg,Cd and their combined pollution on physiological-biochemical characters and the ultrastructural changes in leaves of Lemna minor L. The results indicated that different degree of poisoning symptoms appeared on leaves of different concentrations after cultivated for 4 days. With the increasing pollutant concentration, content of chlorophyll and soluble protein decreased sharply; activity of antioxidant enzyme systems and proline content were stimulated with an obvious resistant peak, but decreased afterwards. Ultrastructure observation revealed that chloroplasts swelled, outer membrane suffered destruction and thylakoids disintegrated; cristae of mitochondria also began to disintegrate after swelling and even vesiculated; nucleus became deformed, with chromatin condensing, and even vacuoted. The results indicated that the toxic effect of Cd was more obvious than that of Hg, the interaction of Hg + Cd showed synergism. As far as the lethal concentration to cell of Lemna minor L. is concerned, Hg ranges from 5 - 7 mg/L, Cd ranges from 2.5 - 5 mg/ L,Hg + Cd ranges from 1 mg/L Hg + 1 mg/L Cd-2.5mg/L Hg + 2.5 mg/L Cd.