On the basis of the investigation of the content and distribution of heavy metals in sediments and benthic organisms from the sewage stream in guangzhou city , the antagonistic effect of selenium on the harm of mercury ( hg2 + ) to the tissues in swordtail fish ( xiphophorus helleri ) , the 22nd offspring purely cultivated by pearl river fishery research institute , were measured by physiological and biochemical indexes and observation of electron microscopy 本研究中首先调查了广州市河涌沉积物及底栖生物体内重金属含量及分布，并以珠江水产研究所培育的水生实验动物?剑尾鱼为实验材料，利用环境生物技术，电镜观察等技术方法研究了重金属?汞对剑尾鱼组织的毒害及机体必需微量元素硒对其毒害的拮抗性影响。
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The main study in this paper included as follows : the content and distribution of heavy metals in sediments and benthic organisms from the sewage stream in guangzhou city ; the acute toxicity and joint toxicity of mercury and selenium to swordtail fish ( xiphophorus helleri ) ; the damage of mercury to the indexes of antioxidant system in the gills and livers in swordtail ( including the measurement of the activities of total antioxidative capacity [ t ~ aoc ] , superoxide dismutase [ sod ] , glutathione peroxidase [ gsh - px ] and the concentration of malondiald - ehyde [ mda ] ) and the relief effects of selenium on it , as well as the physiological damage of mercury on the tissues , namely : the antagonistic effect of na + - k + ~ atpase activity on the tissues between selenite and mercury , and the ultrastructural damage under the exposure of mercury 研究内容主要有：广州市河涌沉积物及底栖生物体内重金属含量及评价；汞和硒对剑尾鱼的急性毒性和联合毒性及安全浓度的评价；汞对剑尾鱼鳃和肝脏中抗氧化系统的毒性，包括对总抗氧化能力、超氧化物歧化酶、谷胱甘肽过氧化物酶活力及丙二醛含量的测定及硒对其保护作用；汞对剑尾鱼组织生理毒性即：汞对na ~ + - k ~ + atpase活力的影响及硒的保护作用和汞和对剑尾鱼组织超微结构的损伤等。以高氯酸?硝酸消化法和火焰原子吸收分光光度法测定了广州市河涌沉积物和底栖生物中重金属含量。
