中文摘要：

以淡水底栖硅藻曲壳藻（Achnanthes kryophila Petersen）为毒理试验材料,研究了重金属镉、铜对曲壳藻生长及抗氧化酶活性的影响。结果表明：镉和铜胁迫96 h EC50分别为：0.984 mg×L–1和1.589 mg×L–1。藻生长量总体随重金属浓度的增加而降低,然而镉（0—0.1 mg×L–1）、铜（0—0.02 mg×L–1）暴露组表现出明显的毒性兴奋效应。曲壳藻可溶性蛋白含量、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性随镉和铜胁迫浓度增加先升高后下降,丙二醛（MDA）含量随着胁迫浓度增高逐渐增大,镉和铜变化趋势大体相同,但是变化幅度不同。高浓度重金属胁迫诱导氧自由基的大量产生,破坏了曲壳藻抗氧化酶系统的动态平衡,加剧了膜脂过氧化作用,影响藻细胞的生长并最终导致细胞死亡。

英文摘要：

With diatom Achnanthes kryophila as research subjects, the effects of heavy metal cadmium and copper on growth and antioxidant enzymes were investigated. The results showed that EC50 （96 h） to A.kryophila was 0.984 mg·L-1 （Cd2＋） and 1.589 mg·L-1 （Cu2＋）, which indicated the toxicity grade was very high. The biomass was restrained with the increasing concentration of both heavy metals generally. But hormesis appeared when the concentration ranged between 0-0.1 mg·L-1 for Cd and 0-0.02 mg·L-1 for Cu; with the increasing concentration of two heavy metals, soluble protein content, activities of SOD, CAT had a sharp decline. MDA content went up constantly. The trends under two medals were the same but the ranges of fluctuation were different. High level of the heavy metals destroyed the antioxidant enzyme system of A. kryophila and led to imbalance between generating and scavenging of free radicals, and then lipid laeroxidation was exacerbated. Finally the algae were dead.