BIOACCUMULATION AND TOXICITY OF Cu AND Zn IN HYDRILLA VERTICILLATA(LINN.F.) ROYLE

In the present study, Hydrilla verticillata(Linn.f.) Royle,a submerged macrophyte widely distributed in China was used as experimental material. Cu and Zn,essential elements for the normal development and growth of plants were selected as the stressfactors. H. verticillata was cultivated in water containing elevated concentrationsof Cu and Zn (up to 10 mg/L) for 7d under lab condition. The bioaccumulation of Cu and Zn were determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP) and their environmental toxicology in H. verticillata was studied. The results suggested that contents of Cu and Zn in H. verticillata were nearly in linear increase with rise of metal concentration in solution,and statistical analysis indicated that they all reached significant positive levels(RCu=0.9875,PZn=0.9990,PHAc> FHCl> FNaCl> FWater> FEthanol> FResidue; Zn:FNaCl> FHAc> FHCl> FEthanol> FResidue> FWater. Auto fluorescent range narrowed; both peak value and average intensity decreased in leaf of H. verticillata under Cu and Zn stress. Scanning and transmission electron microscope observation indicated that Cu and Zn imposed injury action on morphological structure and ultrastructure of leaf cells,such as distortion of cell wall and cell shape,disaggregation of nucleolus,agglutination and disappearance of chromatin of nucleus,disruption of nuclear membrane,swelling of thylakoids and breakage of chloroplast envelope,decreasing of cristae quantity and vacuolization of mitochondria. The conclusion was that there was a significant dose-effect between bioaccumulation and toxicity. Namely,the more the pollutant contents in H. verticillata,the severer the toxicity to the plant.