Toxicity And Sub-lethal Effects Of TNT On Brachydanio Rerio

Trinitrotoluene,alsoknown as TNT, is a yellow dynamite which is widely used in industry,agriculture,transportation, telecommunication,national defense and so on. A large amount ofwaste water and dust contain high concentrations of TNT can be produced in the process ofusing TNT, and cause great potential harm to humans and animals.In this paper,the acute andchronic toxic effect of TNT on the zebra fish （Danio rerio） is studied with the purpose ofunderstanding TNT’s toxicity on the zebra fish.The acute toxicological experiment was carried on mainly with half static methodindoors to determine the TNT’s single acute toxicity on the zebra fish, and the result show thatthe TNT’s 24h-LC₅₀ is 3711.33 ug/L.Moreover,additional observing the TNT’s effect onembryonic development of the zebra fish shows that along with the elevation of TNT’s density,the zebra fish embryo’s hatchability reduces and abnormal rate increases gradually. WhenTNT’s concentration is lower than 927.76 ug/L, embryo’s hatchability reduces and abnormalrate increases steadily. When the concentration is higher than 927.76 ug/L, embryo’s lethalityrate proliferate, hatchability fall subsequently and abnormal rate increase significantly. Whenthe concentration reaches 3711.04 ug/L, the embryo presents the entire lethal effect. Theexperiment had proven that the TNT has more significant influence on the zebra fishembryonic development than the adult fish.In the chronic toxicological experiment the zebra fish was raised in five solutions withdifferent concentrations （0, 0.5, 1, 2, 4 mg/L） of TNT. Changes of the enzyme activity withtime were studied in each organization. The experiment contains two time sections. In thetoxic time section the fishes were raised in TNT solutions for 24 h, 48 h, 72 h, 96 h, then thefishes were put in clean water for 48h or 96 h. At each time point the enzyme activity of eachorganization was determined. The enzymes determined in this experiment includeacetylcholin esterase and lactic dehydrogenase in brain, sodium potassium ATP enzyme ingill, catalase, glutathione peroxidase and sodium potassium ATP enzyme in liver. The resultindicated that the enzyme activity change obviously after the fish was raised in lowconcentration of TNT for 96h and can recover after raised in clean water for 96h. But if thefish was raised in high concentration of TNT for 96h, most enzyme activities can restore aftera longer time. However the ATP enzyme need more time than the others.