高等水生植物中镉的富集分配规律及危害

本文报道了四种水生植物——狐尾藻、水葫芦、紫背萍、荇菜对水体镉污染的反应和它们的净化作用。其结果是:植物的不同种类、不同器官、不同生态习性的不同镉富集量;水体镉浓度与植物的富集量之间有显著相关;富集系数因植物种和器官不同而异;随镉浓度的上升,叶细胞膜受损,叶绿素含量和叶绿素a/b比率下降;植物内部的破坏先于外部;植物的抗性顺序为水葫芦>狐尾藻>荇菜>紫背萍。作者认为水葫芦对水体镉污染具有较理想的净化作用,紫背萍则是较好的监测植物。

UPTAKE, DISTRIBUTION, ACCUMULATION ANDEFIECT OF CADMIUM ON AQUATICVASCULAR PLANTS

The responses of four kinds of aquatic plants-Myriophyllum spicatum, Spirodela polyrrhiza, Eichhornia crassipes and Mymphoides pettatum to Cd-polluted water and their purifying function were studied. Results showed that accumulated amount of Cd in the plants depended on the species, organs and ecological characteristics. The order of Cd content in the species were S. polyrrhiza>M. spicatum>E. crassipes>M. pettatum; in organs, root (rhizome)>leaf; in leaves, M. spicatum>M. pettatum>E. crassipes, in rhizomes, E. crassipes>M. spicatum>M. pettatum. Significant relationships were found between the accumulated Cd content in plant body and the concentration in wastewater. Accumulation coefficient of Cd however, changed with the species and plant organs, and reached a maximum value at 0.005ppm Cd concentration. Between 0.005 and 1 ppm accumulation fell rapidly and after that started to slow down.The accumulation coefficient of M. spicatum decreased with increasing of Cd concentration, while the others fluctuated over 1 ppm. The damaged plants appeared chlorosis, turned yellow and became withered, then decomposed; root was under inhibited growth, necrosis and fell off from the plant. Production of the aquatic plants was thus seriously affected and had significant negative correlation (except M. pettatum) with the Cd concentration. The other bad effects on the plants were damage of the leaf cell membrane, lowering of chlorophyll content and chlorophyll a/b when Cd concentration rose. The damage inside of the plants was prior to that outside. At a lowest Cd concentration appearance did not change at all, but osmosis of the leaf cell, chlorophyll content and chl. achl. b weres eriously affected. It was found that resistance of the plants to that was in the order of E. crassipes>M. spicatum>M. pettatum>S. polyrrhiza. And, E. crassipes can be said of the best purifier for Cd-polluted water and 5. polyrrhiza a good monitor.