水生维管束植物受镉污染后的生理变化及受害机制初探

镉污染后的水生维管束植物其叶绿素a/b值随水体镉浓度的增加而下降,叶绿素含量与镉浓度呈极显著的负相关。叶细胞膜透性与镉浓度呈极显著的正相关。不同抗性种叶片可溶性糖含量均随镉浓度增加而升高,但抗性种的增加率要小得多。镉对根系脱氢酶的活性产生抑制,且随镉浓度升高,活性相应下降。对过氧化物酶同工酶谱也产生明显的影响。这些在环境监测中可作为生理指标。凝胶层析表明,具有抗性的凤眼莲的可溶性成分中,存在着高分子镉复合物(>70,000)、分子量为13,300的镉复合物和低分子量镉螯合物及游离态镉。不抗种的紫背萍缺乏第二种镉复合物。

PRELIMINARY STUDIES ON PHYSIOLOGICAL CHANGES AND INJURY MECHANISM IN AQUATIC VASCULAR PLANTS TREATED WITH CADMIUM

The results of the study on aquatic vascular plants under cadmium (Cd~(++)) pollution show that there is a significant negative correlation between chlorophyll content and Cd~(++) concentration but a strong positive correlation between permeability of cell membrane in the leaf, as judged by exosmosis, and Cd~(++) concentration. Soluble sugars in the leaves of the various species tested increased with the increase of Cd~(++) concentration though the rate of increase is much slower in the resistance species. The activity of dehydrogenase extracted from the root was inhibited by Cd~(++), the inhibition being more pronounced as Cd~(++) concentration increased. Changes in peroxidase isozyme pattern in the plant species studied were related to the Cd~(++) concentration used. The changes reported are useful and effective indices in monitoring the environment. Gel filtration of the soluble fraction shows that in Eichhornia crassipes, a resistant species, Cd~(++) is associated with high molecular weight components (mol wt>70,000 D,) a 13,300 D component, and low molecular weight chelators, and free Cd~(++), while in Spirodela polyrhiza, a non-resistant species, the 13,300 D Cd complex is not found.