Fate and Toxicity Evaluation of Toxic Chemicals in An Aquatic Environment

(1)水环境中微量重金属化学分析的新技术进展(1)采用硅胶固定的8-羟基喹啉流动体系和四氢硼酸还原沉淀法，建立了石墨炉原子吸收光谱分析水中痕量金属的新方法。建立了微波消解石墨炉原子吸收光谱分析沉积物和生物组织样品中痕量金属的快速方法。(2)水环境中化学品的去向影响水环境中化学物去向的主要因素之一是水生生物对化学物的生物转移，特别是通过食物链。分别以椭圆小球藻和大型水蚤作为模型捕食-捕食系统。使用镉和铬作为毒物。The Accept…大型水蚤对这两种金属有更多的摄食刺激。研究了水葫芦对表面活性物质的吸收。微量重金属对微生物的毒性评价。从细菌到高等生物的多种生物都被适当地用于化学品的毒性测试。本研究旨在评价水生态系统中化学物质的毒性，并利用酵母突变株进行环境致突变性检测的新进展。为评价水环境中重金属的生态毒性，研究了重金属通过食物链的生物积累效应。利用椭圆藻和水蚤组成捕食-捕食系统。Cd对小球藻和水蚤的毒性是通过对铬的吸收来刺激的。两种金属之间存在协同作用。研究了酿酒酵母作为一种新的毒力测试材料的可行性。酵母菌比浮游植物更易于处理，生命周期较短，因此作为一种试验生物具有一定的实用价值。它还可以用于使用缺乏DNA修复能力的突变体对化学品进行环境诱变测试。酵母有三种独立的DNA修复系统。利用缺乏一个、两个或全部修复系统的突变体，比较它们对化学物质的毒性敏感性。4NQO损伤的DNA在不同酵母菌株中的修复能力大小顺序为：野生型；切除修复缺陷突变株；突变修复缺陷突变株；重组修复缺陷突变株；具有重组修复系统突变株；具有切除修复系统突变株；较少

The main themes and their results we have obtained are as follows;(1) New Technical Development in Chemical Analysis of Micro Heavy Metals in An Aquatic EnvironmentA simple and accurate method was developed for the determination of trace metals in water by graphite furnace atomic absorption spectrometry(GFAAS) after two preconcentration techniques, (1) flow system utilizing silica-immobilized 8-hydroxyquinoline column and (2)tetrahydroborate reductive precipitation. A rapid method was developed for the determination of trace metals in sediment and biological tissue samples by GFAAS using microwave acid digestion system.(2) Fate of Chemicals in An Aquatic EnvironmentOne of principal factors affecting the fate of chemicals in an aquatic environment is a biotranslocation of chemicals by aquatic organisms, especially through a food chain. Chlorella ellipsoidea and Daphnia magna were used as a model prey - predator system, respectively. Cadmium and Chromium were use as toxichnts. The uptake … More of both metals by Daphinia magna was stimulated by feeding. The uptake of active surface agents by Water hyacinth was investigated. The chemicals inhibited the growth of the plant according to the concentration in the plant.(3) Toxicity Evaluation of Micro Heavy Metals toward Micro-organisms.Many kinds of organisms from bacteria to higher organisms have been properly used for toxicity testing of chemicals according to the objectives. This study aims the toxicity evaluation of chemicals in an aquatic ecosystem and new development of environmental mutaginicty testing using mutants of yeast. The effect of bioaccumulation of heavy metals through a food chain were investigated for the evaluation of eco-toxicity in the aquatic environment. Chrorella ellipsoidea and Daphnia nagna were used for a prey-predator system. The toxicity of Cd for Chlorella and Daphnia was stimulated by the Cr uptake. Both metals interacted synergistically each other. Mortality of Daphnia increased with time and it was stimulated by feeding of Chlorella contaminated with metals.Possibility of Yeast, Saccharomyces cerevisiae as a new testing materials for toxicity testing was studied. Yeast is easier in handling the life cycle is -shorter than phytoplankton, therefore it is pertinent as a test organism. It could also be used for environmental mutaginic testing of chemicals using mutants which are deficient in DNA repair capability. Yeast has three kind of independent DNA repair systems. Mutants which are deficient in one, two or all repair systems were used and compared with each other in toxicity sensitivity to chemical. The order of a repair capability of the DNA damaged by 4NQO in different strains of yeast was as follows:Wild type > Excision repair deficient mutant > Mutation repair deficient mutant > Recombination repair deficient mutant > Mutant having recombination repair system > Mutant having mutation repair system > Mutant having excision repair system > All repair deficient mutant. Less