メダカの卵および仔魚に対するカドミウムの毒性および蓄積性に及ぼす水の硬度の影響

Abstract

Effects of water pH on the toxicity and accumulation of cadmium in the eggs and the larvae of Oryzias latipes were studied. Within the range of pH 4.5-7.0, the toxic effects of Cd2+ on the eggs increased in groups with a lower pH. On the contrary, those effects on the larvae were ameliorated. However, at pH 4.0, the eggs hardly hatched and abnormal symptoms were observed in all larvae of all test groups including control. In the same ranges of pH, the amounts of Cd2+ accumulated by the eggs and the larvae were depressed with lowering pH. Thus, the toxic effects of Cd2+ on the larvae were ameliorated because the amounts of Cd2+ accmulated by the larvae were depressed with lowering water pH. Nevertheless, the reason that the toxic effects of Cd2+ on the eggs increased with lowering water pH could not be explained from the result of Cd2+ accumulation test.