Hg~(2+)、Cd~(2+)及其联合胁迫对伊乐藻的生长及POD和SOD活性的影响

利用水族箱实验研究了伊乐藻的现存量以及POD和SOD活性在Hg2+、Cd2+及其联合胁迫下的响应特点.结果表明:Hg2+和Cd2+对伊乐藻的联合毒性大于单一的毒性;在Hg2+20μmol.L-1,或Cd2+80μmol.L-1,或Hg2++Cd2+50μmol.L-1(Hg2+]/Cd2+]=1/4)时,植物现存量增加的百分比与金属离子浓度负相关;高于上述浓度时,植物现存量减少的速率明显降低.POD和SOD活性的变化趋势相似,在6 h时,其活性在低于40μmol.L-1的Hg2+、或160μmol.L-1的Cd2+、或50μmol.L-1的Hg2++Cd2+胁迫下逐步升高,而在72 h时,相应的胁迫浓度则降至10μmol.L-1、40~80μmol.L-1和25μmol.L-1.

Effects of Hg2+,Cd2+ and Their Combined Stress on the Growth and Activities of POD and SOD of Elodea nuttallii

The effects of Hg~(2+),Cd~(2+) with different concentrations and their combined treatment on standing crop,POD(peroxidase) and SOD(superoxide dismutase) activities of Elodea nuttallii were studied in the aquarium experiments.The combined toxicity of Hg~(2+) + Cd~(2+) to Elodea nuttallii was more serious than that of the single one of them.When Hg~(2+)≤(20 μmol·L~(-1)) or Cd~(2+)≤(80 μmol·L~(-1)) or Hg~(2+) + Cd~(2+)≤10 μmol·L~(-1) Hg~(2+) + 40 μmol·L~(-1) Cd~(2+),there were negative correlations between percentages of the standing crop increasing and concentrations of the metal ions.If concentrations of the metal ions exceeded the concentrations above,the speed of losing standing crop decreased obviously.The changing trends of POD and SOD activities were similar.Their activities increased when Hg~(2+)≤40 μmol·L~(-1),or Cd~(2+)≤160 μmol·L~(-1),or Hg~(2+) + Cd~(2+)≤50 μmol·L~(-1) at the 6~(th) hours;but at the 72~(nd) hours the activities began to decrease when Hg~(2+)≥10 μmol·L~(-1),or Cd~(2+)≥40~80 μmol·L~(-1),or Hg~(2+) + Cd~(2+)≥25 μmol·L~(-1).